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| author | Peter Powell <petpow@saberuk.com> | 2013-11-24 16:20:31 +0000 |
|---|---|---|
| committer | Peter Powell <petpow@saberuk.com> | 2013-12-15 06:46:44 +0000 |
| commit | 7fea7c24c509731040b76191d279972fced7b64c (patch) | |
| tree | 65fc075fad393f4398592016cefa8fd42a6541a9 /docs/rfc | |
| parent | 07d0d8f52f361c64b3c16d7e432f475cd2131a28 (diff) | |
Purge docs/rfc from the repository.
These are of no use to 99% of users and anyone who actually wants
to read them should be capable of using Google to find them.
Diffstat (limited to 'docs/rfc')
| -rw-r--r-- | docs/rfc/rfc1035.txt | 3077 | ||||
| -rw-r--r-- | docs/rfc/rfc1413.txt | 451 | ||||
| -rw-r--r-- | docs/rfc/rfc1459.txt | 3643 |
3 files changed, 0 insertions, 7171 deletions
diff --git a/docs/rfc/rfc1035.txt b/docs/rfc/rfc1035.txt deleted file mode 100644 index b1a9bf5a9..000000000 --- a/docs/rfc/rfc1035.txt +++ /dev/null @@ -1,3077 +0,0 @@ -Network Working Group P. Mockapetris -Request for Comments: 1035 ISI - November 1987 -Obsoletes: RFCs 882, 883, 973 - - DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION - - -1. STATUS OF THIS MEMO - -This RFC describes the details of the domain system and protocol, and -assumes that the reader is familiar with the concepts discussed in a -companion RFC, "Domain Names - Concepts and Facilities" [RFC-1034]. - -The domain system is a mixture of functions and data types which are an -official protocol and functions and data types which are still -experimental. Since the domain system is intentionally extensible, new -data types and experimental behavior should always be expected in parts -of the system beyond the official protocol. The official protocol parts -include standard queries, responses and the Internet class RR data -formats (e.g., host addresses). Since the previous RFC set, several -definitions have changed, so some previous definitions are obsolete. - -Experimental or obsolete features are clearly marked in these RFCs, and -such information should be used with caution. - -The reader is especially cautioned not to depend on the values which -appear in examples to be current or complete, since their purpose is -primarily pedagogical. Distribution of this memo is unlimited. - - Table of Contents - - 1. STATUS OF THIS MEMO 1 - 2. INTRODUCTION 3 - 2.1. Overview 3 - 2.2. Common configurations 4 - 2.3. Conventions 7 - 2.3.1. Preferred name syntax 7 - 2.3.2. Data Transmission Order 8 - 2.3.3. Character Case 9 - 2.3.4. Size limits 10 - 3. DOMAIN NAME SPACE AND RR DEFINITIONS 10 - 3.1. Name space definitions 10 - 3.2. RR definitions 11 - 3.2.1. Format 11 - 3.2.2. TYPE values 12 - 3.2.3. QTYPE values 12 - 3.2.4. CLASS values 13 - - - -Mockapetris [Page 1] - -RFC 1035 Domain Implementation and Specification November 1987 - - - 3.2.5. QCLASS values 13 - 3.3. Standard RRs 13 - 3.3.1. CNAME RDATA format 14 - 3.3.2. HINFO RDATA format 14 - 3.3.3. MB RDATA format (EXPERIMENTAL) 14 - 3.3.4. MD RDATA format (Obsolete) 15 - 3.3.5. MF RDATA format (Obsolete) 15 - 3.3.6. MG RDATA format (EXPERIMENTAL) 16 - 3.3.7. MINFO RDATA format (EXPERIMENTAL) 16 - 3.3.8. MR RDATA format (EXPERIMENTAL) 17 - 3.3.9. MX RDATA format 17 - 3.3.10. NULL RDATA format (EXPERIMENTAL) 17 - 3.3.11. NS RDATA format 18 - 3.3.12. PTR RDATA format 18 - 3.3.13. SOA RDATA format 19 - 3.3.14. TXT RDATA format 20 - 3.4. ARPA Internet specific RRs 20 - 3.4.1. A RDATA format 20 - 3.4.2. WKS RDATA format 21 - 3.5. IN-ADDR.ARPA domain 22 - 3.6. Defining new types, classes, and special namespaces 24 - 4. MESSAGES 25 - 4.1. Format 25 - 4.1.1. Header section format 26 - 4.1.2. Question section format 28 - 4.1.3. Resource record format 29 - 4.1.4. Message compression 30 - 4.2. Transport 32 - 4.2.1. UDP usage 32 - 4.2.2. TCP usage 32 - 5. MASTER FILES 33 - 5.1. Format 33 - 5.2. Use of master files to define zones 35 - 5.3. Master file example 36 - 6. NAME SERVER IMPLEMENTATION 37 - 6.1. Architecture 37 - 6.1.1. Control 37 - 6.1.2. Database 37 - 6.1.3. Time 39 - 6.2. Standard query processing 39 - 6.3. Zone refresh and reload processing 39 - 6.4. Inverse queries (Optional) 40 - 6.4.1. The contents of inverse queries and responses 40 - 6.4.2. Inverse query and response example 41 - 6.4.3. Inverse query processing 42 - - - - - - -Mockapetris [Page 2] - -RFC 1035 Domain Implementation and Specification November 1987 - - - 6.5. Completion queries and responses 42 - 7. RESOLVER IMPLEMENTATION 43 - 7.1. Transforming a user request into a query 43 - 7.2. Sending the queries 44 - 7.3. Processing responses 46 - 7.4. Using the cache 47 - 8. MAIL SUPPORT 47 - 8.1. Mail exchange binding 48 - 8.2. Mailbox binding (Experimental) 48 - 9. REFERENCES and BIBLIOGRAPHY 50 - Index 54 - -2. INTRODUCTION - -2.1. Overview - -The goal of domain names is to provide a mechanism for naming resources -in such a way that the names are usable in different hosts, networks, -protocol families, internets, and administrative organizations. - -From the user's point of view, domain names are useful as arguments to a -local agent, called a resolver, which retrieves information associated -with the domain name. Thus a user might ask for the host address or -mail information associated with a particular domain name. To enable -the user to request a particular type of information, an appropriate -query type is passed to the resolver with the domain name. To the user, -the domain tree is a single information space; the resolver is -responsible for hiding the distribution of data among name servers from -the user. - -From the resolver's point of view, the database that makes up the domain -space is distributed among various name servers. Different parts of the -domain space are stored in different name servers, although a particular -data item will be stored redundantly in two or more name servers. The -resolver starts with knowledge of at least one name server. When the -resolver processes a user query it asks a known name server for the -information; in return, the resolver either receives the desired -information or a referral to another name server. Using these -referrals, resolvers learn the identities and contents of other name -servers. Resolvers are responsible for dealing with the distribution of -the domain space and dealing with the effects of name server failure by -consulting redundant databases in other servers. - -Name servers manage two kinds of data. The first kind of data held in -sets called zones; each zone is the complete database for a particular -"pruned" subtree of the domain space. This data is called -authoritative. A name server periodically checks to make sure that its -zones are up to date, and if not, obtains a new copy of updated zones - - - -Mockapetris [Page 3] - -RFC 1035 Domain Implementation and Specification November 1987 - - -from master files stored locally or in another name server. The second -kind of data is cached data which was acquired by a local resolver. -This data may be incomplete, but improves the performance of the -retrieval process when non-local data is repeatedly accessed. Cached -data is eventually discarded by a timeout mechanism. - -This functional structure isolates the problems of user interface, -failure recovery, and distribution in the resolvers and isolates the -database update and refresh problems in the name servers. - -2.2. Common configurations - -A host can participate in the domain name system in a number of ways, -depending on whether the host runs programs that retrieve information -from the domain system, name servers that answer queries from other -hosts, or various combinations of both functions. The simplest, and -perhaps most typical, configuration is shown below: - - Local Host | Foreign - | - +---------+ +----------+ | +--------+ - | | user queries | |queries | | | - | User |-------------->| |---------|->|Foreign | - | Program | | Resolver | | | Name | - | |<--------------| |<--------|--| Server | - | | user responses| |responses| | | - +---------+ +----------+ | +--------+ - | A | - cache additions | | references | - V | | - +----------+ | - | cache | | - +----------+ | - -User programs interact with the domain name space through resolvers; the -format of user queries and user responses is specific to the host and -its operating system. User queries will typically be operating system -calls, and the resolver and its cache will be part of the host operating -system. Less capable hosts may choose to implement the resolver as a -subroutine to be linked in with every program that needs its services. -Resolvers answer user queries with information they acquire via queries -to foreign name servers and the local cache. - -Note that the resolver may have to make several queries to several -different foreign name servers to answer a particular user query, and -hence the resolution of a user query may involve several network -accesses and an arbitrary amount of time. The queries to foreign name -servers and the corresponding responses have a standard format described - - - -Mockapetris [Page 4] - -RFC 1035 Domain Implementation and Specification November 1987 - - -in this memo, and may be datagrams. - -Depending on its capabilities, a name server could be a stand alone -program on a dedicated machine or a process or processes on a large -timeshared host. A simple configuration might be: - - Local Host | Foreign - | - +---------+ | - / /| | - +---------+ | +----------+ | +--------+ - | | | | |responses| | | - | | | | Name |---------|->|Foreign | - | Master |-------------->| Server | | |Resolver| - | files | | | |<--------|--| | - | |/ | | queries | +--------+ - +---------+ +----------+ | - -Here a primary name server acquires information about one or more zones -by reading master files from its local file system, and answers queries -about those zones that arrive from foreign resolvers. - -The DNS requires that all zones be redundantly supported by more than -one name server. Designated secondary servers can acquire zones and -check for updates from the primary server using the zone transfer -protocol of the DNS. This configuration is shown below: - - Local Host | Foreign - | - +---------+ | - / /| | - +---------+ | +----------+ | +--------+ - | | | | |responses| | | - | | | | Name |---------|->|Foreign | - | Master |-------------->| Server | | |Resolver| - | files | | | |<--------|--| | - | |/ | | queries | +--------+ - +---------+ +----------+ | - A |maintenance | +--------+ - | +------------|->| | - | queries | |Foreign | - | | | Name | - +------------------|--| Server | - maintenance responses | +--------+ - -In this configuration, the name server periodically establishes a -virtual circuit to a foreign name server to acquire a copy of a zone or -to check that an existing copy has not changed. The messages sent for - - - -Mockapetris [Page 5] - -RFC 1035 Domain Implementation and Specification November 1987 - - -these maintenance activities follow the same form as queries and -responses, but the message sequences are somewhat different. - -The information flow in a host that supports all aspects of the domain -name system is shown below: - - Local Host | Foreign - | - +---------+ +----------+ | +--------+ - | | user queries | |queries | | | - | User |-------------->| |---------|->|Foreign | - | Program | | Resolver | | | Name | - | |<--------------| |<--------|--| Server | - | | user responses| |responses| | | - +---------+ +----------+ | +--------+ - | A | - cache additions | | references | - V | | - +----------+ | - | Shared | | - | database | | - +----------+ | - A | | - +---------+ refreshes | | references | - / /| | V | - +---------+ | +----------+ | +--------+ - | | | | |responses| | | - | | | | Name |---------|->|Foreign | - | Master |-------------->| Server | | |Resolver| - | files | | | |<--------|--| | - | |/ | | queries | +--------+ - +---------+ +----------+ | - A |maintenance | +--------+ - | +------------|->| | - | queries | |Foreign | - | | | Name | - +------------------|--| Server | - maintenance responses | +--------+ - -The shared database holds domain space data for the local name server -and resolver. The contents of the shared database will typically be a -mixture of authoritative data maintained by the periodic refresh -operations of the name server and cached data from previous resolver -requests. The structure of the domain data and the necessity for -synchronization between name servers and resolvers imply the general -characteristics of this database, but the actual format is up to the -local implementor. - - - - -Mockapetris [Page 6] - -RFC 1035 Domain Implementation and Specification November 1987 - - -Information flow can also be tailored so that a group of hosts act -together to optimize activities. Sometimes this is done to offload less -capable hosts so that they do not have to implement a full resolver. -This can be appropriate for PCs or hosts which want to minimize the -amount of new network code which is required. This scheme can also -allow a group of hosts can share a small number of caches rather than -maintaining a large number of separate caches, on the premise that the -centralized caches will have a higher hit ratio. In either case, -resolvers are replaced with stub resolvers which act as front ends to -resolvers located in a recursive server in one or more name servers -known to perform that service: - - Local Hosts | Foreign - | - +---------+ | - | | responses | - | Stub |<--------------------+ | - | Resolver| | | - | |----------------+ | | - +---------+ recursive | | | - queries | | | - V | | - +---------+ recursive +----------+ | +--------+ - | | queries | |queries | | | - | Stub |-------------->| Recursive|---------|->|Foreign | - | Resolver| | Server | | | Name | - | |<--------------| |<--------|--| Server | - +---------+ responses | |responses| | | - +----------+ | +--------+ - | Central | | - | cache | | - +----------+ | - -In any case, note that domain components are always replicated for -reliability whenever possible. - -2.3. Conventions - -The domain system has several conventions dealing with low-level, but -fundamental, issues. While the implementor is free to violate these -conventions WITHIN HIS OWN SYSTEM, he must observe these conventions in -ALL behavior observed from other hosts. - -2.3.1. Preferred name syntax - -The DNS specifications attempt to be as general as possible in the rules -for constructing domain names. The idea is that the name of any -existing object can be expressed as a domain name with minimal changes. - - - -Mockapetris [Page 7] - -RFC 1035 Domain Implementation and Specification November 1987 - - -However, when assigning a domain name for an object, the prudent user -will select a name which satisfies both the rules of the domain system -and any existing rules for the object, whether these rules are published -or implied by existing programs. - -For example, when naming a mail domain, the user should satisfy both the -rules of this memo and those in RFC-822. When creating a new host name, -the old rules for HOSTS.TXT should be followed. This avoids problems -when old software is converted to use domain names. - -The following syntax will result in fewer problems with many - -applications that use domain names (e.g., mail, TELNET). - -<domain> ::= <subdomain> | " " - -<subdomain> ::= <label> | <subdomain> "." <label> - -<label> ::= <letter> [ [ <ldh-str> ] <let-dig> ] - -<ldh-str> ::= <let-dig-hyp> | <let-dig-hyp> <ldh-str> - -<let-dig-hyp> ::= <let-dig> | "-" - -<let-dig> ::= <letter> | <digit> - -<letter> ::= any one of the 52 alphabetic characters A through Z in -upper case and a through z in lower case - -<digit> ::= any one of the ten digits 0 through 9 - -Note that while upper and lower case letters are allowed in domain -names, no significance is attached to the case. That is, two names with -the same spelling but different case are to be treated as if identical. - -The labels must follow the rules for ARPANET host names. They must -start with a letter, end with a letter or digit, and have as interior -characters only letters, digits, and hyphen. There are also some -restrictions on the length. Labels must be 63 characters or less. - -For example, the following strings identify hosts in the Internet: - -A.ISI.EDU XX.LCS.MIT.EDU SRI-NIC.ARPA - -2.3.2. Data Transmission Order - -The order of transmission of the header and data described in this -document is resolved to the octet level. Whenever a diagram shows a - - - -Mockapetris [Page 8] - -RFC 1035 Domain Implementation and Specification November 1987 - - -group of octets, the order of transmission of those octets is the normal -order in which they are read in English. For example, in the following -diagram, the octets are transmitted in the order they are numbered. - - 0 1 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | 1 | 2 | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | 3 | 4 | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | 5 | 6 | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - -Whenever an octet represents a numeric quantity, the left most bit in -the diagram is the high order or most significant bit. That is, the bit -labeled 0 is the most significant bit. For example, the following -diagram represents the value 170 (decimal). - - 0 1 2 3 4 5 6 7 - +-+-+-+-+-+-+-+-+ - |1 0 1 0 1 0 1 0| - +-+-+-+-+-+-+-+-+ - -Similarly, whenever a multi-octet field represents a numeric quantity -the left most bit of the whole field is the most significant bit. When -a multi-octet quantity is transmitted the most significant octet is -transmitted first. - -2.3.3. Character Case - -For all parts of the DNS that are part of the official protocol, all -comparisons between character strings (e.g., labels, domain names, etc.) -are done in a case-insensitive manner. At present, this rule is in -force throughout the domain system without exception. However, future -additions beyond current usage may need to use the full binary octet -capabilities in names, so attempts to store domain names in 7-bit ASCII -or use of special bytes to terminate labels, etc., should be avoided. - -When data enters the domain system, its original case should be -preserved whenever possible. In certain circumstances this cannot be -done. For example, if two RRs are stored in a database, one at x.y and -one at X.Y, they are actually stored at the same place in the database, -and hence only one casing would be preserved. The basic rule is that -case can be discarded only when data is used to define structure in a -database, and two names are identical when compared in a case -insensitive manner. - - - - -Mockapetris [Page 9] - -RFC 1035 Domain Implementation and Specification November 1987 - - -Loss of case sensitive data must be minimized. Thus while data for x.y -and X.Y may both be stored under a single location x.y or X.Y, data for -a.x and B.X would never be stored under A.x, A.X, b.x, or b.X. In -general, this preserves the case of the first label of a domain name, -but forces standardization of interior node labels. - -Systems administrators who enter data into the domain database should -take care to represent the data they supply to the domain system in a -case-consistent manner if their system is case-sensitive. The data -distribution system in the domain system will ensure that consistent -representations are preserved. - -2.3.4. Size limits - -Various objects and parameters in the DNS have size limits. They are -listed below. Some could be easily changed, others are more -fundamental. - -labels 63 octets or less - -names 255 octets or less - -TTL positive values of a signed 32 bit number. - -UDP messages 512 octets or less - -3. DOMAIN NAME SPACE AND RR DEFINITIONS - -3.1. Name space definitions - -Domain names in messages are expressed in terms of a sequence of labels. -Each label is represented as a one octet length field followed by that -number of octets. Since every domain name ends with the null label of -the root, a domain name is terminated by a length byte of zero. The -high order two bits of every length octet must be zero, and the -remaining six bits of the length field limit the label to 63 octets or -less. - -To simplify implementations, the total length of a domain name (i.e., -label octets and label length octets) is restricted to 255 octets or -less. - -Although labels can contain any 8 bit values in octets that make up a -label, it is strongly recommended that labels follow the preferred -syntax described elsewhere in this memo, which is compatible with -existing host naming conventions. Name servers and resolvers must -compare labels in a case-insensitive manner (i.e., A=a), assuming ASCII -with zero parity. Non-alphabetic codes must match exactly. - - - -Mockapetris [Page 10] - -RFC 1035 Domain Implementation and Specification November 1987 - - -3.2. RR definitions - -3.2.1. Format - -All RRs have the same top level format shown below: - - 1 1 1 1 1 1 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | | - / / - / NAME / - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | TYPE | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | CLASS | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | TTL | - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | RDLENGTH | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--| - / RDATA / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - - -where: - -NAME an owner name, i.e., the name of the node to which this - resource record pertains. - -TYPE two octets containing one of the RR TYPE codes. - -CLASS two octets containing one of the RR CLASS codes. - -TTL a 32 bit signed integer that specifies the time interval - that the resource record may be cached before the source - of the information should again be consulted. Zero - values are interpreted to mean that the RR can only be - used for the transaction in progress, and should not be - cached. For example, SOA records are always distributed - with a zero TTL to prohibit caching. Zero values can - also be used for extremely volatile data. - -RDLENGTH an unsigned 16 bit integer that specifies the length in - octets of the RDATA field. - - - -Mockapetris [Page 11] - -RFC 1035 Domain Implementation and Specification November 1987 - - -RDATA a variable length string of octets that describes the - resource. The format of this information varies - according to the TYPE and CLASS of the resource record. - -3.2.2. TYPE values - -TYPE fields are used in resource records. Note that these types are a -subset of QTYPEs. - -TYPE value and meaning - -A 1 a host address - -NS 2 an authoritative name server - -MD 3 a mail destination (Obsolete - use MX) - -MF 4 a mail forwarder (Obsolete - use MX) - -CNAME 5 the canonical name for an alias - -SOA 6 marks the start of a zone of authority - -MB 7 a mailbox domain name (EXPERIMENTAL) - -MG 8 a mail group member (EXPERIMENTAL) - -MR 9 a mail rename domain name (EXPERIMENTAL) - -NULL 10 a null RR (EXPERIMENTAL) - -WKS 11 a well known service description - -PTR 12 a domain name pointer - -HINFO 13 host information - -MINFO 14 mailbox or mail list information - -MX 15 mail exchange - -TXT 16 text strings - -3.2.3. QTYPE values - -QTYPE fields appear in the question part of a query. QTYPES are a -superset of TYPEs, hence all TYPEs are valid QTYPEs. In addition, the -following QTYPEs are defined: - - - -Mockapetris [Page 12] - -RFC 1035 Domain Implementation and Specification November 1987 - - -AXFR 252 A request for a transfer of an entire zone - -MAILB 253 A request for mailbox-related records (MB, MG or MR) - -MAILA 254 A request for mail agent RRs (Obsolete - see MX) - -* 255 A request for all records - -3.2.4. CLASS values - -CLASS fields appear in resource records. The following CLASS mnemonics -and values are defined: - -IN 1 the Internet - -CS 2 the CSNET class (Obsolete - used only for examples in - some obsolete RFCs) - -CH 3 the CHAOS class - -HS 4 Hesiod [Dyer 87] - -3.2.5. QCLASS values - -QCLASS fields appear in the question section of a query. QCLASS values -are a superset of CLASS values; every CLASS is a valid QCLASS. In -addition to CLASS values, the following QCLASSes are defined: - -* 255 any class - -3.3. Standard RRs - -The following RR definitions are expected to occur, at least -potentially, in all classes. In particular, NS, SOA, CNAME, and PTR -will be used in all classes, and have the same format in all classes. -Because their RDATA format is known, all domain names in the RDATA -section of these RRs may be compressed. - -<domain-name> is a domain name represented as a series of labels, and -terminated by a label with zero length. <character-string> is a single -length octet followed by that number of characters. <character-string> -is treated as binary information, and can be up to 256 characters in -length (including the length octet). - - - - - - - - -Mockapetris [Page 13] - -RFC 1035 Domain Implementation and Specification November 1987 - - -3.3.1. CNAME RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / CNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -CNAME A <domain-name> which specifies the canonical or primary - name for the owner. The owner name is an alias. - -CNAME RRs cause no additional section processing, but name servers may -choose to restart the query at the canonical name in certain cases. See -the description of name server logic in [RFC-1034] for details. - -3.3.2. HINFO RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / CPU / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / OS / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -CPU A <character-string> which specifies the CPU type. - -OS A <character-string> which specifies the operating - system type. - -Standard values for CPU and OS can be found in [RFC-1010]. - -HINFO records are used to acquire general information about a host. The -main use is for protocols such as FTP that can use special procedures -when talking between machines or operating systems of the same type. - -3.3.3. MB RDATA format (EXPERIMENTAL) - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / MADNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -MADNAME A <domain-name> which specifies a host which has the - specified mailbox. - - - -Mockapetris [Page 14] - -RFC 1035 Domain Implementation and Specification November 1987 - - -MB records cause additional section processing which looks up an A type -RRs corresponding to MADNAME. - -3.3.4. MD RDATA format (Obsolete) - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / MADNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -MADNAME A <domain-name> which specifies a host which has a mail - agent for the domain which should be able to deliver - mail for the domain. - -MD records cause additional section processing which looks up an A type -record corresponding to MADNAME. - -MD is obsolete. See the definition of MX and [RFC-974] for details of -the new scheme. The recommended policy for dealing with MD RRs found in -a master file is to reject them, or to convert them to MX RRs with a -preference of 0. - -3.3.5. MF RDATA format (Obsolete) - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / MADNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -MADNAME A <domain-name> which specifies a host which has a mail - agent for the domain which will accept mail for - forwarding to the domain. - -MF records cause additional section processing which looks up an A type -record corresponding to MADNAME. - -MF is obsolete. See the definition of MX and [RFC-974] for details ofw -the new scheme. The recommended policy for dealing with MD RRs found in -a master file is to reject them, or to convert them to MX RRs with a -preference of 10. - - - - - - - -Mockapetris [Page 15] - -RFC 1035 Domain Implementation and Specification November 1987 - - -3.3.6. MG RDATA format (EXPERIMENTAL) - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / MGMNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -MGMNAME A <domain-name> which specifies a mailbox which is a - member of the mail group specified by the domain name. - -MG records cause no additional section processing. - -3.3.7. MINFO RDATA format (EXPERIMENTAL) - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / RMAILBX / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / EMAILBX / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -RMAILBX A <domain-name> which specifies a mailbox which is - responsible for the mailing list or mailbox. If this - domain name names the root, the owner of the MINFO RR is - responsible for itself. Note that many existing mailing - lists use a mailbox X-request for the RMAILBX field of - mailing list X, e.g., Msgroup-request for Msgroup. This - field provides a more general mechanism. - - -EMAILBX A <domain-name> which specifies a mailbox which is to - receive error messages related to the mailing list or - mailbox specified by the owner of the MINFO RR (similar - to the ERRORS-TO: field which has been proposed). If - this domain name names the root, errors should be - returned to the sender of the message. - -MINFO records cause no additional section processing. Although these -records can be associated with a simple mailbox, they are usually used -with a mailing list. - - - - - - - - -Mockapetris [Page 16] - -RFC 1035 Domain Implementation and Specification November 1987 - - -3.3.8. MR RDATA format (EXPERIMENTAL) - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / NEWNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -NEWNAME A <domain-name> which specifies a mailbox which is the - proper rename of the specified mailbox. - -MR records cause no additional section processing. The main use for MR -is as a forwarding entry for a user who has moved to a different -mailbox. - -3.3.9. MX RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | PREFERENCE | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / EXCHANGE / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -PREFERENCE A 16 bit integer which specifies the preference given to - this RR among others at the same owner. Lower values - are preferred. - -EXCHANGE A <domain-name> which specifies a host willing to act as - a mail exchange for the owner name. - -MX records cause type A additional section processing for the host -specified by EXCHANGE. The use of MX RRs is explained in detail in -[RFC-974]. - -3.3.10. NULL RDATA format (EXPERIMENTAL) - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / <anything> / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -Anything at all may be in the RDATA field so long as it is 65535 octets -or less. - - - - -Mockapetris [Page 17] - -RFC 1035 Domain Implementation and Specification November 1987 - - -NULL records cause no additional section processing. NULL RRs are not -allowed in master files. NULLs are used as placeholders in some -experimental extensions of the DNS. - -3.3.11. NS RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / NSDNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -NSDNAME A <domain-name> which specifies a host which should be - authoritative for the specified class and domain. - -NS records cause both the usual additional section processing to locate -a type A record, and, when used in a referral, a special search of the -zone in which they reside for glue information. - -The NS RR states that the named host should be expected to have a zone -starting at owner name of the specified class. Note that the class may -not indicate the protocol family which should be used to communicate -with the host, although it is typically a strong hint. For example, -hosts which are name servers for either Internet (IN) or Hesiod (HS) -class information are normally queried using IN class protocols. - -3.3.12. PTR RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / PTRDNAME / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -PTRDNAME A <domain-name> which points to some location in the - domain name space. - -PTR records cause no additional section processing. These RRs are used -in special domains to point to some other location in the domain space. -These records are simple data, and don't imply any special processing -similar to that performed by CNAME, which identifies aliases. See the -description of the IN-ADDR.ARPA domain for an example. - - - - - - - - -Mockapetris [Page 18] - -RFC 1035 Domain Implementation and Specification November 1987 - - -3.3.13. SOA RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / MNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / RNAME / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | SERIAL | - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | REFRESH | - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | RETRY | - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | EXPIRE | - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | MINIMUM | - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -MNAME The <domain-name> of the name server that was the - original or primary source of data for this zone. - -RNAME A <domain-name> which specifies the mailbox of the - person responsible for this zone. - -SERIAL The unsigned 32 bit version number of the original copy - of the zone. Zone transfers preserve this value. This - value wraps and should be compared using sequence space - arithmetic. - -REFRESH A 32 bit time interval before the zone should be - refreshed. - -RETRY A 32 bit time interval that should elapse before a - failed refresh should be retried. - -EXPIRE A 32 bit time value that specifies the upper limit on - the time interval that can elapse before the zone is no - longer authoritative. - - - - - -Mockapetris [Page 19] - -RFC 1035 Domain Implementation and Specification November 1987 - - -MINIMUM The unsigned 32 bit minimum TTL field that should be - exported with any RR from this zone. - -SOA records cause no additional section processing. - -All times are in units of seconds. - -Most of these fields are pertinent only for name server maintenance -operations. However, MINIMUM is used in all query operations that -retrieve RRs from a zone. Whenever a RR is sent in a response to a -query, the TTL field is set to the maximum of the TTL field from the RR -and the MINIMUM field in the appropriate SOA. Thus MINIMUM is a lower -bound on the TTL field for all RRs in a zone. Note that this use of -MINIMUM should occur when the RRs are copied into the response and not -when the zone is loaded from a master file or via a zone transfer. The -reason for this provison is to allow future dynamic update facilities to -change the SOA RR with known semantics. - - -3.3.14. TXT RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - / TXT-DATA / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -TXT-DATA One or more <character-string>s. - -TXT RRs are used to hold descriptive text. The semantics of the text -depends on the domain where it is found. - -3.4. Internet specific RRs - -3.4.1. A RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | ADDRESS | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -ADDRESS A 32 bit Internet address. - -Hosts that have multiple Internet addresses will have multiple A -records. - - - - - -Mockapetris [Page 20] - -RFC 1035 Domain Implementation and Specification November 1987 - - -A records cause no additional section processing. The RDATA section of -an A line in a master file is an Internet address expressed as four -decimal numbers separated by dots without any imbedded spaces (e.g., -"10.2.0.52" or "192.0.5.6"). - -3.4.2. WKS RDATA format - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | ADDRESS | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | PROTOCOL | | - +--+--+--+--+--+--+--+--+ | - | | - / <BIT MAP> / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -ADDRESS An 32 bit Internet address - -PROTOCOL An 8 bit IP protocol number - -<BIT MAP> A variable length bit map. The bit map must be a - multiple of 8 bits long. - -The WKS record is used to describe the well known services supported by -a particular protocol on a particular internet address. The PROTOCOL -field specifies an IP protocol number, and the bit map has one bit per -port of the specified protocol. The first bit corresponds to port 0, -the second to port 1, etc. If the bit map does not include a bit for a -protocol of interest, that bit is assumed zero. The appropriate values -and mnemonics for ports and protocols are specified in [RFC-1010]. - -For example, if PROTOCOL=TCP (6), the 26th bit corresponds to TCP port -25 (SMTP). If this bit is set, a SMTP server should be listening on TCP -port 25; if zero, SMTP service is not supported on the specified -address. - -The purpose of WKS RRs is to provide availability information for -servers for TCP and UDP. If a server supports both TCP and UDP, or has -multiple Internet addresses, then multiple WKS RRs are used. - -WKS RRs cause no additional section processing. - -In master files, both ports and protocols are expressed using mnemonics -or decimal numbers. - - - - -Mockapetris [Page 21] - -RFC 1035 Domain Implementation and Specification November 1987 - - -3.5. IN-ADDR.ARPA domain - -The Internet uses a special domain to support gateway location and -Internet address to host mapping. Other classes may employ a similar -strategy in other domains. The intent of this domain is to provide a -guaranteed method to perform host address to host name mapping, and to -facilitate queries to locate all gateways on a particular network in the -Internet. - -Note that both of these services are similar to functions that could be -performed by inverse queries; the difference is that this part of the -domain name space is structured according to address, and hence can -guarantee that the appropriate data can be located without an exhaustive -search of the domain space. - -The domain begins at IN-ADDR.ARPA and has a substructure which follows -the Internet addressing structure. - -Domain names in the IN-ADDR.ARPA domain are defined to have up to four -labels in addition to the IN-ADDR.ARPA suffix. Each label represents -one octet of an Internet address, and is expressed as a character string -for a decimal value in the range 0-255 (with leading zeros omitted -except in the case of a zero octet which is represented by a single -zero). - -Host addresses are represented by domain names that have all four labels -specified. Thus data for Internet address 10.2.0.52 is located at -domain name 52.0.2.10.IN-ADDR.ARPA. The reversal, though awkward to -read, allows zones to be delegated which are exactly one network of -address space. For example, 10.IN-ADDR.ARPA can be a zone containing -data for the ARPANET, while 26.IN-ADDR.ARPA can be a separate zone for -MILNET. Address nodes are used to hold pointers to primary host names -in the normal domain space. - -Network numbers correspond to some non-terminal nodes at various depths -in the IN-ADDR.ARPA domain, since Internet network numbers are either 1, -2, or 3 octets. Network nodes are used to hold pointers to the primary -host names of gateways attached to that network. Since a gateway is, by -definition, on more than one network, it will typically have two or more -network nodes which point at it. Gateways will also have host level -pointers at their fully qualified addresses. - -Both the gateway pointers at network nodes and the normal host pointers -at full address nodes use the PTR RR to point back to the primary domain -names of the corresponding hosts. - -For example, the IN-ADDR.ARPA domain will contain information about the -ISI gateway between net 10 and 26, an MIT gateway from net 10 to MIT's - - - -Mockapetris [Page 22] - -RFC 1035 Domain Implementation and Specification November 1987 - - -net 18, and hosts A.ISI.EDU and MULTICS.MIT.EDU. Assuming that ISI -gateway has addresses 10.2.0.22 and 26.0.0.103, and a name MILNET- -GW.ISI.EDU, and the MIT gateway has addresses 10.0.0.77 and 18.10.0.4 -and a name GW.LCS.MIT.EDU, the domain database would contain: - - 10.IN-ADDR.ARPA. PTR MILNET-GW.ISI.EDU. - 10.IN-ADDR.ARPA. PTR GW.LCS.MIT.EDU. - 18.IN-ADDR.ARPA. PTR GW.LCS.MIT.EDU. - 26.IN-ADDR.ARPA. PTR MILNET-GW.ISI.EDU. - 22.0.2.10.IN-ADDR.ARPA. PTR MILNET-GW.ISI.EDU. - 103.0.0.26.IN-ADDR.ARPA. PTR MILNET-GW.ISI.EDU. - 77.0.0.10.IN-ADDR.ARPA. PTR GW.LCS.MIT.EDU. - 4.0.10.18.IN-ADDR.ARPA. PTR GW.LCS.MIT.EDU. - 103.0.3.26.IN-ADDR.ARPA. PTR A.ISI.EDU. - 6.0.0.10.IN-ADDR.ARPA. PTR MULTICS.MIT.EDU. - -Thus a program which wanted to locate gateways on net 10 would originate -a query of the form QTYPE=PTR, QCLASS=IN, QNAME=10.IN-ADDR.ARPA. It -would receive two RRs in response: - - 10.IN-ADDR.ARPA. PTR MILNET-GW.ISI.EDU. - 10.IN-ADDR.ARPA. PTR GW.LCS.MIT.EDU. - -The program could then originate QTYPE=A, QCLASS=IN queries for MILNET- -GW.ISI.EDU. and GW.LCS.MIT.EDU. to discover the Internet addresses of -these gateways. - -A resolver which wanted to find the host name corresponding to Internet -host address 10.0.0.6 would pursue a query of the form QTYPE=PTR, -QCLASS=IN, QNAME=6.0.0.10.IN-ADDR.ARPA, and would receive: - - 6.0.0.10.IN-ADDR.ARPA. PTR MULTICS.MIT.EDU. - -Several cautions apply to the use of these services: - - Since the IN-ADDR.ARPA special domain and the normal domain - for a particular host or gateway will be in different zones, - the possibility exists that that the data may be inconsistent. - - - Gateways will often have two names in separate domains, only - one of which can be primary. - - - Systems that use the domain database to initialize their - routing tables must start with enough gateway information to - guarantee that they can access the appropriate name server. - - - The gateway data only reflects the existence of a gateway in a - manner equivalent to the current HOSTS.TXT file. It doesn't - replace the dynamic availability information from GGP or EGP. - - - -Mockapetris [Page 23] - -RFC 1035 Domain Implementation and Specification November 1987 - - -3.6. Defining new types, classes, and special namespaces - -The previously defined types and classes are the ones in use as of the -date of this memo. New definitions should be expected. This section -makes some recommendations to designers considering additions to the -existing facilities. The mailing list NAMEDROPPERS@SRI-NIC.ARPA is the -forum where general discussion of design issues takes place. - -In general, a new type is appropriate when new information is to be -added to the database about an existing object, or we need new data -formats for some totally new object. Designers should attempt to define -types and their RDATA formats that are generally applicable to all -classes, and which avoid duplication of information. New classes are -appropriate when the DNS is to be used for a new protocol, etc which -requires new class-specific data formats, or when a copy of the existing -name space is desired, but a separate management domain is necessary. - -New types and classes need mnemonics for master files; the format of the -master files requires that the mnemonics for type and class be disjoint. - -TYPE and CLASS values must be a proper subset of QTYPEs and QCLASSes -respectively. - -The present system uses multiple RRs to represent multiple values of a -type rather than storing multiple values in the RDATA section of a -single RR. This is less efficient for most applications, but does keep -RRs shorter. The multiple RRs assumption is incorporated in some -experimental work on dynamic update methods. - -The present system attempts to minimize the duplication of data in the -database in order to insure consistency. Thus, in order to find the -address of the host for a mail exchange, you map the mail domain name to -a host name, then the host name to addresses, rather than a direct -mapping to host address. This approach is preferred because it avoids -the opportunity for inconsistency. - -In defining a new type of data, multiple RR types should not be used to -create an ordering between entries or express different formats for -equivalent bindings, instead this information should be carried in the -body of the RR and a single type used. This policy avoids problems with -caching multiple types and defining QTYPEs to match multiple types. - -For example, the original form of mail exchange binding used two RR -types one to represent a "closer" exchange (MD) and one to represent a -"less close" exchange (MF). The difficulty is that the presence of one -RR type in a cache doesn't convey any information about the other -because the query which acquired the cached information might have used -a QTYPE of MF, MD, or MAILA (which matched both). The redesigned - - - -Mockapetris [Page 24] - -RFC 1035 Domain Implementation and Specification November 1987 - - -service used a single type (MX) with a "preference" value in the RDATA -section which can order different RRs. However, if any MX RRs are found -in the cache, then all should be there. - -4. MESSAGES - -4.1. Format - -All communications inside of the domain protocol are carried in a single -format called a message. The top level format of message is divided -into 5 sections (some of which are empty in certain cases) shown below: - - +---------------------+ - | Header | - +---------------------+ - | Question | the question for the name server - +---------------------+ - | Answer | RRs answering the question - +---------------------+ - | Authority | RRs pointing toward an authority - +---------------------+ - | Additional | RRs holding additional information - +---------------------+ - -The header section is always present. The header includes fields that -specify which of the remaining sections are present, and also specify -whether the message is a query or a response, a standard query or some -other opcode, etc. - -The names of the sections after the header are derived from their use in -standard queries. The question section contains fields that describe a -question to a name server. These fields are a query type (QTYPE), a -query class (QCLASS), and a query domain name (QNAME). The last three -sections have the same format: a possibly empty list of concatenated -resource records (RRs). The answer section contains RRs that answer the -question; the authority section contains RRs that point toward an -authoritative name server; the additional records section contains RRs -which relate to the query, but are not strictly answers for the -question. - - - - - - - - - - - - -Mockapetris [Page 25] - -RFC 1035 Domain Implementation and Specification November 1987 - - -4.1.1. Header section format - -The header contains the following fields: - - 1 1 1 1 1 1 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | ID | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - |QR| Opcode |AA|TC|RD|RA| Z | RCODE | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | QDCOUNT | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | ANCOUNT | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | NSCOUNT | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | ARCOUNT | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -ID A 16 bit identifier assigned by the program that - generates any kind of query. This identifier is copied - the corresponding reply and can be used by the requester - to match up replies to outstanding queries. - -QR A one bit field that specifies whether this message is a - query (0), or a response (1). - -OPCODE A four bit field that specifies kind of query in this - message. This value is set by the originator of a query - and copied into the response. The values are: - - 0 a standard query (QUERY) - - 1 an inverse query (IQUERY) - - 2 a server status request (STATUS) - - 3-15 reserved for future use - -AA Authoritative Answer - this bit is valid in responses, - and specifies that the responding name server is an - authority for the domain name in question section. - - Note that the contents of the answer section may have - multiple owner names because of aliases. The AA bit - - - -Mockapetris [Page 26] - -RFC 1035 Domain Implementation and Specification November 1987 - - - corresponds to the name which matches the query name, or - the first owner name in the answer section. - -TC TrunCation - specifies that this message was truncated - due to length greater than that permitted on the - transmission channel. - -RD Recursion Desired - this bit may be set in a query and - is copied into the response. If RD is set, it directs - the name server to pursue the query recursively. - Recursive query support is optional. - -RA Recursion Available - this be is set or cleared in a - response, and denotes whether recursive query support is - available in the name server. - -Z Reserved for future use. Must be zero in all queries - and responses. - -RCODE Response code - this 4 bit field is set as part of - responses. The values have the following - interpretation: - - 0 No error condition - - 1 Format error - The name server was - unable to interpret the query. - - 2 Server failure - The name server was - unable to process this query due to a - problem with the name server. - - 3 Name Error - Meaningful only for - responses from an authoritative name - server, this code signifies that the - domain name referenced in the query does - not exist. - - 4 Not Implemented - The name server does - not support the requested kind of query. - - 5 Refused - The name server refuses to - perform the specified operation for - policy reasons. For example, a name - server may not wish to provide the - information to the particular requester, - or a name server may not wish to perform - a particular operation (e.g., zone - - - -Mockapetris [Page 27] - -RFC 1035 Domain Implementation and Specification November 1987 - - - transfer) for particular data. - - 6-15 Reserved for future use. - -QDCOUNT an unsigned 16 bit integer specifying the number of - entries in the question section. - -ANCOUNT an unsigned 16 bit integer specifying the number of - resource records in the answer section. - -NSCOUNT an unsigned 16 bit integer specifying the number of name - server resource records in the authority records - section. - -ARCOUNT an unsigned 16 bit integer specifying the number of - resource records in the additional records section. - -4.1.2. Question section format - -The question section is used to carry the "question" in most queries, -i.e., the parameters that define what is being asked. The section -contains QDCOUNT (usually 1) entries, each of the following format: - - 1 1 1 1 1 1 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | | - / QNAME / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | QTYPE | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | QCLASS | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -QNAME a domain name represented as a sequence of labels, where - each label consists of a length octet followed by that - number of octets. The domain name terminates with the - zero length octet for the null label of the root. Note - that this field may be an odd number of octets; no - padding is used. - -QTYPE a two octet code which specifies the type of the query. - The values for this field include all codes valid for a - TYPE field, together with some more general codes which - can match more than one type of RR. - - - -Mockapetris [Page 28] - -RFC 1035 Domain Implementation and Specification November 1987 - - -QCLASS a two octet code that specifies the class of the query. - For example, the QCLASS field is IN for the Internet. - -4.1.3. Resource record format - -The answer, authority, and additional sections all share the same -format: a variable number of resource records, where the number of -records is specified in the corresponding count field in the header. -Each resource record has the following format: - 1 1 1 1 1 1 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | | - / / - / NAME / - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | TYPE | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | CLASS | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | TTL | - | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | RDLENGTH | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--| - / RDATA / - / / - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -where: - -NAME a domain name to which this resource record pertains. - -TYPE two octets containing one of the RR type codes. This - field specifies the meaning of the data in the RDATA - field. - -CLASS two octets which specify the class of the data in the - RDATA field. - -TTL a 32 bit unsigned integer that specifies the time - interval (in seconds) that the resource record may be - cached before it should be discarded. Zero values are - interpreted to mean that the RR can only be used for the - transaction in progress, and should not be cached. - - - - - -Mockapetris [Page 29] - -RFC 1035 Domain Implementation and Specification November 1987 - - -RDLENGTH an unsigned 16 bit integer that specifies the length in - octets of the RDATA field. - -RDATA a variable length string of octets that describes the - resource. The format of this information varies - according to the TYPE and CLASS of the resource record. - For example, the if the TYPE is A and the CLASS is IN, - the RDATA field is a 4 octet ARPA Internet address. - -4.1.4. Message compression - -In order to reduce the size of messages, the domain system utilizes a -compression scheme which eliminates the repetition of domain names in a -message. In this scheme, an entire domain name or a list of labels at -the end of a domain name is replaced with a pointer to a prior occurance -of the same name. - -The pointer takes the form of a two octet sequence: - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - | 1 1| OFFSET | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -The first two bits are ones. This allows a pointer to be distinguished -from a label, since the label must begin with two zero bits because -labels are restricted to 63 octets or less. (The 10 and 01 combinations -are reserved for future use.) The OFFSET field specifies an offset from -the start of the message (i.e., the first octet of the ID field in the -domain header). A zero offset specifies the first byte of the ID field, -etc. - -The compression scheme allows a domain name in a message to be -represented as either: - - - a sequence of labels ending in a zero octet - - - a pointer - - - a sequence of labels ending with a pointer - -Pointers can only be used for occurances of a domain name where the -format is not class specific. If this were not the case, a name server -or resolver would be required to know the format of all RRs it handled. -As yet, there are no such cases, but they may occur in future RDATA -formats. - -If a domain name is contained in a part of the message subject to a -length field (such as the RDATA section of an RR), and compression is - - - -Mockapetris [Page 30] - -RFC 1035 Domain Implementation and Specification November 1987 - - -used, the length of the compressed name is used in the length -calculation, rather than the length of the expanded name. - -Programs are free to avoid using pointers in messages they generate, -although this will reduce datagram capacity, and may cause truncation. -However all programs are required to understand arriving messages that -contain pointers. - -For example, a datagram might need to use the domain names F.ISI.ARPA, -FOO.F.ISI.ARPA, ARPA, and the root. Ignoring the other fields of the -message, these domain names might be represented as: - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 20 | 1 | F | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 22 | 3 | I | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 24 | S | I | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 26 | 4 | A | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 28 | R | P | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 30 | A | 0 | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 40 | 3 | F | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 42 | O | O | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 44 | 1 1| 20 | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 64 | 1 1| 26 | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - 92 | 0 | | - +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ - -The domain name for F.ISI.ARPA is shown at offset 20. The domain name -FOO.F.ISI.ARPA is shown at offset 40; this definition uses a pointer to -concatenate a label for FOO to the previously defined F.ISI.ARPA. The -domain name ARPA is defined at offset 64 using a pointer to the ARPA -component of the name F.ISI.ARPA at 20; note that this pointer relies on -ARPA being the last label in the string at 20. The root domain name is - - - -Mockapetris [Page 31] - -RFC 1035 Domain Implementation and Specification November 1987 - - -defined by a single octet of zeros at 92; the root domain name has no -labels. - -4.2. Transport - -The DNS assumes that messages will be transmitted as datagrams or in a -byte stream carried by a virtual circuit. While virtual circuits can be -used for any DNS activity, datagrams are preferred for queries due to -their lower overhead and better performance. Zone refresh activities -must use virtual circuits because of the need for reliable transfer. - -The Internet supports name server access using TCP [RFC-793] on server -port 53 (decimal) as well as datagram access using UDP [RFC-768] on UDP -port 53 (decimal). - -4.2.1. UDP usage - -Messages sent using UDP user server port 53 (decimal). - -Messages carried by UDP are restricted to 512 bytes (not counting the IP -or UDP headers). Longer messages are truncated and the TC bit is set in -the header. - -UDP is not acceptable for zone transfers, but is the recommended method -for standard queries in the Internet. Queries sent using UDP may be -lost, and hence a retransmission strategy is required. Queries or their -responses may be reordered by the network, or by processing in name -servers, so resolvers should not depend on them being returned in order. - -The optimal UDP retransmission policy will vary with performance of the -Internet and the needs of the client, but the following are recommended: - - - The client should try other servers and server addresses - before repeating a query to a specific address of a server. - - - The retransmission interval should be based on prior - statistics if possible. Too aggressive retransmission can - easily slow responses for the community at large. Depending - on how well connected the client is to its expected servers, - the minimum retransmission interval should be 2-5 seconds. - -More suggestions on server selection and retransmission policy can be -found in the resolver section of this memo. - -4.2.2. TCP usage - -Messages sent over TCP connections use server port 53 (decimal). The -message is prefixed with a two byte length field which gives the message - - - -Mockapetris [Page 32] - -RFC 1035 Domain Implementation and Specification November 1987 - - -length, excluding the two byte length field. This length field allows -the low-level processing to assemble a complete message before beginning -to parse it. - -Several connection management policies are recommended: - - - The server should not block other activities waiting for TCP - data. - - - The server should support multiple connections. - - - The server should assume that the client will initiate - connection closing, and should delay closing its end of the - connection until all outstanding client requests have been - satisfied. - - - If the server needs to close a dormant connection to reclaim - resources, it should wait until the connection has been idle - for a period on the order of two minutes. In particular, the - server should allow the SOA and AXFR request sequence (which - begins a refresh operation) to be made on a single connection. - Since the server would be unable to answer queries anyway, a - unilateral close or reset may be used instead of a graceful - close. - -5. MASTER FILES - -Master files are text files that contain RRs in text form. Since the -contents of a zone can be expressed in the form of a list of RRs a -master file is most often used to define a zone, though it can be used -to list a cache's contents. Hence, this section first discusses the -format of RRs in a master file, and then the special considerations when -a master file is used to create a zone in some name server. - -5.1. Format - -The format of these files is a sequence of entries. Entries are -predominantly line-oriented, though parentheses can be used to continue -a list of items across a line boundary, and text literals can contain -CRLF within the text. Any combination of tabs and spaces act as a -delimiter between the separate items that make up an entry. The end of -any line in the master file can end with a comment. The comment starts -with a ";" (semicolon). - -The following entries are defined: - - <blank>[<comment>] - - - - -Mockapetris [Page 33] - -RFC 1035 Domain Implementation and Specification November 1987 - - - $ORIGIN <domain-name> [<comment>] - - $INCLUDE <file-name> [<domain-name>] [<comment>] - - <domain-name><rr> [<comment>] - - <blank><rr> [<comment>] - -Blank lines, with or without comments, are allowed anywhere in the file. - -Two control entries are defined: $ORIGIN and $INCLUDE. $ORIGIN is -followed by a domain name, and resets the current origin for relative -domain names to the stated name. $INCLUDE inserts the named file into -the current file, and may optionally specify a domain name that sets the -relative domain name origin for the included file. $INCLUDE may also -have a comment. Note that a $INCLUDE entry never changes the relative -origin of the parent file, regardless of changes to the relative origin -made within the included file. - -The last two forms represent RRs. If an entry for an RR begins with a -blank, then the RR is assumed to be owned by the last stated owner. If -an RR entry begins with a <domain-name>, then the owner name is reset. - -<rr> contents take one of the following forms: - - [<TTL>] [<class>] <type> <RDATA> - - [<class>] [<TTL>] <type> <RDATA> - -The RR begins with optional TTL and class fields, followed by a type and -RDATA field appropriate to the type and class. Class and type use the -standard mnemonics, TTL is a decimal integer. Omitted class and TTL -values are default to the last explicitly stated values. Since type and -class mnemonics are disjoint, the parse is unique. (Note that this -order is different from the order used in examples and the order used in -the actual RRs; the given order allows easier parsing and defaulting.) - -<domain-name>s make up a large share of the data in the master file. -The labels in the domain name are expressed as character strings and -separated by dots. Quoting conventions allow arbitrary characters to be -stored in domain names. Domain names that end in a dot are called -absolute, and are taken as complete. Domain names which do not end in a -dot are called relative; the actual domain name is the concatenation of -the relative part with an origin specified in a $ORIGIN, $INCLUDE, or as -an argument to the master file loading routine. A relative name is an -error when no origin is available. - - - - - -Mockapetris [Page 34] - -RFC 1035 Domain Implementation and Specification November 1987 - - -<character-string> is expressed in one or two ways: as a contiguous set -of characters without interior spaces, or as a string beginning with a " -and ending with a ". Inside a " delimited string any character can -occur, except for a " itself, which must be quoted using \ (back slash). - -Because these files are text files several special encodings are -necessary to allow arbitrary data to be loaded. In particular: - - of the root. - -@ A free standing @ is used to denote the current origin. - -\X where X is any character other than a digit (0-9), is - used to quote that character so that its special meaning - does not apply. For example, "\." can be used to place - a dot character in a label. - -\DDD where each D is a digit is the octet corresponding to - the decimal number described by DDD. The resulting - octet is assumed to be text and is not checked for - special meaning. - -( ) Parentheses are used to group data that crosses a line - boundary. In effect, line terminations are not - recognized within parentheses. - -; Semicolon is used to start a comment; the remainder of - the line is ignored. - -5.2. Use of master files to define zones - -When a master file is used to load a zone, the operation should be -suppressed if any errors are encountered in the master file. The -rationale for this is that a single error can have widespread -consequences. For example, suppose that the RRs defining a delegation -have syntax errors; then the server will return authoritative name -errors for all names in the subzone (except in the case where the -subzone is also present on the server). - -Several other validity checks that should be performed in addition to -insuring that the file is syntactically correct: - - 1. All RRs in the file should have the same class. - - 2. Exactly one SOA RR should be present at the top of the zone. - - 3. If delegations are present and glue information is required, - it should be present. - - - -Mockapetris [Page 35] - -RFC 1035 Domain Implementation and Specification November 1987 - - - 4. Information present outside of the authoritative nodes in the - zone should be glue information, rather than the result of an - origin or similar error. - -5.3. Master file example - -The following is an example file which might be used to define the -ISI.EDU zone.and is loaded with an origin of ISI.EDU: - -@ IN SOA VENERA Action\.domains ( - 20 ; SERIAL - 7200 ; REFRESH - 600 ; RETRY - 3600000; EXPIRE - 60) ; MINIMUM - - NS A.ISI.EDU. - NS VENERA - NS VAXA - MX 10 VENERA - MX 20 VAXA - -A A 26.3.0.103 - -VENERA A 10.1.0.52 - A 128.9.0.32 - -VAXA A 10.2.0.27 - A 128.9.0.33 - - -$INCLUDE <SUBSYS>ISI-MAILBOXES.TXT - -Where the file <SUBSYS>ISI-MAILBOXES.TXT is: - - MOE MB A.ISI.EDU. - LARRY MB A.ISI.EDU. - CURLEY MB A.ISI.EDU. - STOOGES MG MOE - MG LARRY - MG CURLEY - -Note the use of the \ character in the SOA RR to specify the responsible -person mailbox "Action.domains@E.ISI.EDU". - - - - - - - -Mockapetris [Page 36] - -RFC 1035 Domain Implementation and Specification November 1987 - - -6. NAME SERVER IMPLEMENTATION - -6.1. Architecture - -The optimal structure for the name server will depend on the host -operating system and whether the name server is integrated with resolver -operations, either by supporting recursive service, or by sharing its -database with a resolver. This section discusses implementation -considerations for a name server which shares a database with a -resolver, but most of these concerns are present in any name server. - -6.1.1. Control - -A name server must employ multiple concurrent activities, whether they -are implemented as separate tasks in the host's OS or multiplexing -inside a single name server program. It is simply not acceptable for a -name server to block the service of UDP requests while it waits for TCP -data for refreshing or query activities. Similarly, a name server -should not attempt to provide recursive service without processing such -requests in parallel, though it may choose to serialize requests from a -single client, or to regard identical requests from the same client as -duplicates. A name server should not substantially delay requests while -it reloads a zone from master files or while it incorporates a newly -refreshed zone into its database. - -6.1.2. Database - -While name server implementations are free to use any internal data -structures they choose, the suggested structure consists of three major -parts: - - - A "catalog" data structure which lists the zones available to - this server, and a "pointer" to the zone data structure. The - main purpose of this structure is to find the nearest ancestor - zone, if any, for arriving standard queries. - - - Separate data structures for each of the zones held by the - name server. - - - A data structure for cached data. (or perhaps separate caches - for different classes) - -All of these data structures can be implemented an identical tree -structure format, with different data chained off the nodes in different -parts: in the catalog the data is pointers to zones, while in the zone -and cache data structures, the data will be RRs. In designing the tree -framework the designer should recognize that query processing will need -to traverse the tree using case-insensitive label comparisons; and that - - - -Mockapetris [Page 37] - -RFC 1035 Domain Implementation and Specification November 1987 - - -in real data, a few nodes have a very high branching factor (100-1000 or -more), but the vast majority have a very low branching factor (0-1). - -One way to solve the case problem is to store the labels for each node -in two pieces: a standardized-case representation of the label where all -ASCII characters are in a single case, together with a bit mask that -denotes which characters are actually of a different case. The -branching factor diversity can be handled using a simple linked list for -a node until the branching factor exceeds some threshold, and -transitioning to a hash structure after the threshold is exceeded. In -any case, hash structures used to store tree sections must insure that -hash functions and procedures preserve the casing conventions of the -DNS. - -The use of separate structures for the different parts of the database -is motivated by several factors: - - - The catalog structure can be an almost static structure that - need change only when the system administrator changes the - zones supported by the server. This structure can also be - used to store parameters used to control refreshing - activities. - - - The individual data structures for zones allow a zone to be - replaced simply by changing a pointer in the catalog. Zone - refresh operations can build a new structure and, when - complete, splice it into the database via a simple pointer - replacement. It is very important that when a zone is - refreshed, queries should not use old and new data - simultaneously. - - - With the proper search procedures, authoritative data in zones - will always "hide", and hence take precedence over, cached - data. - - - Errors in zone definitions that cause overlapping zones, etc., - may cause erroneous responses to queries, but problem - determination is simplified, and the contents of one "bad" - zone can't corrupt another. - - - Since the cache is most frequently updated, it is most - vulnerable to corruption during system restarts. It can also - become full of expired RR data. In either case, it can easily - be discarded without disturbing zone data. - -A major aspect of database design is selecting a structure which allows -the name server to deal with crashes of the name server's host. State -information which a name server should save across system crashes - - - -Mockapetris [Page 38] - -RFC 1035 Domain Implementation and Specification November 1987 - - -includes the catalog structure (including the state of refreshing for -each zone) and the zone data itself. - -6.1.3. Time - -Both the TTL data for RRs and the timing data for refreshing activities -depends on 32 bit timers in units of seconds. Inside the database, -refresh timers and TTLs for cached data conceptually "count down", while -data in the zone stays with constant TTLs. - -A recommended implementation strategy is to store time in two ways: as -a relative increment and as an absolute time. One way to do this is to -use positive 32 bit numbers for one type and negative numbers for the -other. The RRs in zones use relative times; the refresh timers and -cache data use absolute times. Absolute numbers are taken with respect -to some known origin and converted to relative values when placed in the -response to a query. When an absolute TTL is negative after conversion -to relative, then the data is expired and should be ignored. - -6.2. Standard query processing - -The major algorithm for standard query processing is presented in -[RFC-1034]. - -When processing queries with QCLASS=*, or some other QCLASS which -matches multiple classes, the response should never be authoritative -unless the server can guarantee that the response covers all classes. - -When composing a response, RRs which are to be inserted in the -additional section, but duplicate RRs in the answer or authority -sections, may be omitted from the additional section. - -When a response is so long that truncation is required, the truncation -should start at the end of the response and work forward in the -datagram. Thus if there is any data for the authority section, the -answer section is guaranteed to be unique. - -The MINIMUM value in the SOA should be used to set a floor on the TTL of -data distributed from a zone. This floor function should be done when -the data is copied into a response. This will allow future dynamic -update protocols to change the SOA MINIMUM field without ambiguous -semantics. - -6.3. Zone refresh and reload processing - -In spite of a server's best efforts, it may be unable to load zone data -from a master file due to syntax errors, etc., or be unable to refresh a -zone within the its expiration parameter. In this case, the name server - - - -Mockapetris [Page 39] - -RFC 1035 Domain Implementation and Specification November 1987 - - -should answer queries as if it were not supposed to possess the zone. - -If a master is sending a zone out via AXFR, and a new version is created -during the transfer, the master should continue to send the old version -if possible. In any case, it should never send part of one version and -part of another. If completion is not possible, the master should reset -the connection on which the zone transfer is taking place. - -6.4. Inverse queries (Optional) - -Inverse queries are an optional part of the DNS. Name servers are not -required to support any form of inverse queries. If a name server -receives an inverse query that it does not support, it returns an error -response with the "Not Implemented" error set in the header. While -inverse query support is optional, all name servers must be at least -able to return the error response. - -6.4.1. The contents of inverse queries and responses Inverse -queries reverse the mappings performed by standard query operations; -while a standard query maps a domain name to a resource, an inverse -query maps a resource to a domain name. For example, a standard query -might bind a domain name to a host address; the corresponding inverse -query binds the host address to a domain name. - -Inverse queries take the form of a single RR in the answer section of -the message, with an empty question section. The owner name of the -query RR and its TTL are not significant. The response carries -questions in the question section which identify all names possessing -the query RR WHICH THE NAME SERVER KNOWS. Since no name server knows -about all of the domain name space, the response can never be assumed to -be complete. Thus inverse queries are primarily useful for database -management and debugging activities. Inverse queries are NOT an -acceptable method of mapping host addresses to host names; use the IN- -ADDR.ARPA domain instead. - -Where possible, name servers should provide case-insensitive comparisons -for inverse queries. Thus an inverse query asking for an MX RR of -"Venera.isi.edu" should get the same response as a query for -"VENERA.ISI.EDU"; an inverse query for HINFO RR "IBM-PC UNIX" should -produce the same result as an inverse query for "IBM-pc unix". However, -this cannot be guaranteed because name servers may possess RRs that -contain character strings but the name server does not know that the -data is character. - -When a name server processes an inverse query, it either returns: - - 1. zero, one, or multiple domain names for the specified - resource as QNAMEs in the question section - - - -Mockapetris [Page 40] - -RFC 1035 Domain Implementation and Specification November 1987 - - - 2. an error code indicating that the name server doesn't support - inverse mapping of the specified resource type. - -When the response to an inverse query contains one or more QNAMEs, the -owner name and TTL of the RR in the answer section which defines the -inverse query is modified to exactly match an RR found at the first -QNAME. - -RRs returned in the inverse queries cannot be cached using the same -mechanism as is used for the replies to standard queries. One reason -for this is that a name might have multiple RRs of the same type, and -only one would appear. For example, an inverse query for a single -address of a multiply homed host might create the impression that only -one address existed. - -6.4.2. Inverse query and response example The overall structure -of an inverse query for retrieving the domain name that corresponds to -Internet address 10.1.0.52 is shown below: - - +-----------------------------------------+ - Header | OPCODE=IQUERY, ID=997 | - +-----------------------------------------+ - Question | <empty> | - +-----------------------------------------+ - Answer | <anyname> A IN 10.1.0.52 | - +-----------------------------------------+ - Authority | <empty> | - +-----------------------------------------+ - Additional | <empty> | - +-----------------------------------------+ - -This query asks for a question whose answer is the Internet style -address 10.1.0.52. Since the owner name is not known, any domain name -can be used as a placeholder (and is ignored). A single octet of zero, -signifying the root, is usually used because it minimizes the length of -the message. The TTL of the RR is not significant. The response to -this query might be: - - - - - - - - - - - - - - -Mockapetris [Page 41] - -RFC 1035 Domain Implementation and Specification November 1987 - - - +-----------------------------------------+ - Header | OPCODE=RESPONSE, ID=997 | - +-----------------------------------------+ - Question |QTYPE=A, QCLASS=IN, QNAME=VENERA.ISI.EDU | - +-----------------------------------------+ - Answer | VENERA.ISI.EDU A IN 10.1.0.52 | - +-----------------------------------------+ - Authority | <empty> | - +-----------------------------------------+ - Additional | <empty> | - +-----------------------------------------+ - -Note that the QTYPE in a response to an inverse query is the same as the -TYPE field in the answer section of the inverse query. Responses to -inverse queries may contain multiple questions when the inverse is not -unique. If the question section in the response is not empty, then the -RR in the answer section is modified to correspond to be an exact copy -of an RR at the first QNAME. - -6.4.3. Inverse query processing - -Name servers that support inverse queries can support these operations -through exhaustive searches of their databases, but this becomes -impractical as the size of the database increases. An alternative -approach is to invert the database according to the search key. - -For name servers that support multiple zones and a large amount of data, -the recommended approach is separate inversions for each zone. When a -particular zone is changed during a refresh, only its inversions need to -be redone. - -Support for transfer of this type of inversion may be included in future -versions of the domain system, but is not supported in this version. - -6.5. Completion queries and responses - -The optional completion services described in RFC-882 and RFC-883 have -been deleted. Redesigned services may become available in the future. - - - - - - - - - - - - - -Mockapetris [Page 42] - -RFC 1035 Domain Implementation and Specification November 1987 - - -7. RESOLVER IMPLEMENTATION - -The top levels of the recommended resolver algorithm are discussed in -[RFC-1034]. This section discusses implementation details assuming the -database structure suggested in the name server implementation section -of this memo. - -7.1. Transforming a user request into a query - -The first step a resolver takes is to transform the client's request, -stated in a format suitable to the local OS, into a search specification -for RRs at a specific name which match a specific QTYPE and QCLASS. -Where possible, the QTYPE and QCLASS should correspond to a single type -and a single class, because this makes the use of cached data much -simpler. The reason for this is that the presence of data of one type -in a cache doesn't confirm the existence or non-existence of data of -other types, hence the only way to be sure is to consult an -authoritative source. If QCLASS=* is used, then authoritative answers -won't be available. - -Since a resolver must be able to multiplex multiple requests if it is to -perform its function efficiently, each pending request is usually -represented in some block of state information. This state block will -typically contain: - - - A timestamp indicating the time the request began. - The timestamp is used to decide whether RRs in the database - can be used or are out of date. This timestamp uses the - absolute time format previously discussed for RR storage in - zones and caches. Note that when an RRs TTL indicates a - relative time, the RR must be timely, since it is part of a - zone. When the RR has an absolute time, it is part of a - cache, and the TTL of the RR is compared against the timestamp - for the start of the request. - - Note that using the timestamp is superior to using a current - time, since it allows RRs with TTLs of zero to be entered in - the cache in the usual manner, but still used by the current - request, even after intervals of many seconds due to system - load, query retransmission timeouts, etc. - - - Some sort of parameters to limit the amount of work which will - be performed for this request. - - The amount of work which a resolver will do in response to a - client request must be limited to guard against errors in the - database, such as circular CNAME references, and operational - problems, such as network partition which prevents the - - - -Mockapetris [Page 43] - -RFC 1035 Domain Implementation and Specification November 1987 - - - resolver from accessing the name servers it needs. While - local limits on the number of times a resolver will retransmit - a particular query to a particular name server address are - essential, the resolver should have a global per-request - counter to limit work on a single request. The counter should - be set to some initial value and decremented whenever the - resolver performs any action (retransmission timeout, - retransmission, etc.) If the counter passes zero, the request - is terminated with a temporary error. - - Note that if the resolver structure allows one request to - start others in parallel, such as when the need to access a - name server for one request causes a parallel resolve for the - name server's addresses, the spawned request should be started - with a lower counter. This prevents circular references in - the database from starting a chain reaction of resolver - activity. - - - The SLIST data structure discussed in [RFC-1034]. - - This structure keeps track of the state of a request if it - must wait for answers from foreign name servers. - -7.2. Sending the queries - -As described in [RFC-1034], the basic task of the resolver is to -formulate a query which will answer the client's request and direct that -query to name servers which can provide the information. The resolver -will usually only have very strong hints about which servers to ask, in -the form of NS RRs, and may have to revise the query, in response to -CNAMEs, or revise the set of name servers the resolver is asking, in -response to delegation responses which point the resolver to name -servers closer to the desired information. In addition to the -information requested by the client, the resolver may have to call upon -its own services to determine the address of name servers it wishes to -contact. - -In any case, the model used in this memo assumes that the resolver is -multiplexing attention between multiple requests, some from the client, -and some internally generated. Each request is represented by some -state information, and the desired behavior is that the resolver -transmit queries to name servers in a way that maximizes the probability -that the request is answered, minimizes the time that the request takes, -and avoids excessive transmissions. The key algorithm uses the state -information of the request to select the next name server address to -query, and also computes a timeout which will cause the next action -should a response not arrive. The next action will usually be a -transmission to some other server, but may be a temporary error to the - - - -Mockapetris [Page 44] - -RFC 1035 Domain Implementation and Specification November 1987 - - -client. - -The resolver always starts with a list of server names to query (SLIST). -This list will be all NS RRs which correspond to the nearest ancestor -zone that the resolver knows about. To avoid startup problems, the -resolver should have a set of default servers which it will ask should -it have no current NS RRs which are appropriate. The resolver then adds -to SLIST all of the known addresses for the name servers, and may start -parallel requests to acquire the addresses of the servers when the -resolver has the name, but no addresses, for the name servers. - -To complete initialization of SLIST, the resolver attaches whatever -history information it has to the each address in SLIST. This will -usually consist of some sort of weighted averages for the response time -of the address, and the batting average of the address (i.e., how often -the address responded at all to the request). Note that this -information should be kept on a per address basis, rather than on a per -name server basis, because the response time and batting average of a -particular server may vary considerably from address to address. Note -also that this information is actually specific to a resolver address / -server address pair, so a resolver with multiple addresses may wish to -keep separate histories for each of its addresses. Part of this step -must deal with addresses which have no such history; in this case an -expected round trip time of 5-10 seconds should be the worst case, with -lower estimates for the same local network, etc. - -Note that whenever a delegation is followed, the resolver algorithm -reinitializes SLIST. - -The information establishes a partial ranking of the available name -server addresses. Each time an address is chosen and the state should -be altered to prevent its selection again until all other addresses have -been tried. The timeout for each transmission should be 50-100% greater -than the average predicted value to allow for variance in response. - -Some fine points: - - - The resolver may encounter a situation where no addresses are - available for any of the name servers named in SLIST, and - where the servers in the list are precisely those which would - normally be used to look up their own addresses. This - situation typically occurs when the glue address RRs have a - smaller TTL than the NS RRs marking delegation, or when the - resolver caches the result of a NS search. The resolver - should detect this condition and restart the search at the - next ancestor zone, or alternatively at the root. - - - - - -Mockapetris [Page 45] - -RFC 1035 Domain Implementation and Specification November 1987 - - - - If a resolver gets a server error or other bizarre response - from a name server, it should remove it from SLIST, and may - wish to schedule an immediate transmission to the next - candidate server address. - -7.3. Processing responses - -The first step in processing arriving response datagrams is to parse the -response. This procedure should include: - - - Check the header for reasonableness. Discard datagrams which - are queries when responses are expected. - - - Parse the sections of the message, and insure that all RRs are - correctly formatted. - - - As an optional step, check the TTLs of arriving data looking - for RRs with excessively long TTLs. If a RR has an - excessively long TTL, say greater than 1 week, either discard - the whole response, or limit all TTLs in the response to 1 - week. - -The next step is to match the response to a current resolver request. -The recommended strategy is to do a preliminary matching using the ID -field in the domain header, and then to verify that the question section -corresponds to the information currently desired. This requires that -the transmission algorithm devote several bits of the domain ID field to -a request identifier of some sort. This step has several fine points: - - - Some name servers send their responses from different - addresses than the one used to receive the query. That is, a - resolver cannot rely that a response will come from the same - address which it sent the corresponding query to. This name - server bug is typically encountered in UNIX systems. - - - If the resolver retransmits a particular request to a name - server it should be able to use a response from any of the - transmissions. However, if it is using the response to sample - the round trip time to access the name server, it must be able - to determine which transmission matches the response (and keep - transmission times for each outgoing message), or only - calculate round trip times based on initial transmissions. - - - A name server will occasionally not have a current copy of a - zone which it should have according to some NS RRs. The - resolver should simply remove the name server from the current - SLIST, and continue. - - - - -Mockapetris [Page 46] - -RFC 1035 Domain Implementation and Specification November 1987 - - -7.4. Using the cache - -In general, we expect a resolver to cache all data which it receives in -responses since it may be useful in answering future client requests. -However, there are several types of data which should not be cached: - - - When several RRs of the same type are available for a - particular owner name, the resolver should either cache them - all or none at all. When a response is truncated, and a - resolver doesn't know whether it has a complete set, it should - not cache a possibly partial set of RRs. - - - Cached data should never be used in preference to - authoritative data, so if caching would cause this to happen - the data should not be cached. - - - The results of an inverse query should not be cached. - - - The results of standard queries where the QNAME contains "*" - labels if the data might be used to construct wildcards. The - reason is that the cache does not necessarily contain existing - RRs or zone boundary information which is necessary to - restrict the application of the wildcard RRs. - - - RR data in responses of dubious reliability. When a resolver - receives unsolicited responses or RR data other than that - requested, it should discard it without caching it. The basic - implication is that all sanity checks on a packet should be - performed before any of it is cached. - -In a similar vein, when a resolver has a set of RRs for some name in a -response, and wants to cache the RRs, it should check its cache for -already existing RRs. Depending on the circumstances, either the data -in the response or the cache is preferred, but the two should never be -combined. If the data in the response is from authoritative data in the -answer section, it is always preferred. - -8. MAIL SUPPORT - -The domain system defines a standard for mapping mailboxes into domain -names, and two methods for using the mailbox information to derive mail -routing information. The first method is called mail exchange binding -and the other method is mailbox binding. The mailbox encoding standard -and mail exchange binding are part of the DNS official protocol, and are -the recommended method for mail routing in the Internet. Mailbox -binding is an experimental feature which is still under development and -subject to change. - - - - -Mockapetris [Page 47] - -RFC 1035 Domain Implementation and Specification November 1987 - - -The mailbox encoding standard assumes a mailbox name of the form -"<local-part>@<mail-domain>". While the syntax allowed in each of these -sections varies substantially between the various mail internets, the -preferred syntax for the ARPA Internet is given in [RFC-822]. - -The DNS encodes the <local-part> as a single label, and encodes the -<mail-domain> as a domain name. The single label from the <local-part> -is prefaced to the domain name from <mail-domain> to form the domain -name corresponding to the mailbox. Thus the mailbox HOSTMASTER@SRI- -NIC.ARPA is mapped into the domain name HOSTMASTER.SRI-NIC.ARPA. If the -<local-part> contains dots or other special characters, its -representation in a master file will require the use of backslash -quoting to ensure that the domain name is properly encoded. For -example, the mailbox Action.domains@ISI.EDU would be represented as -Action\.domains.ISI.EDU. - -8.1. Mail exchange binding - -Mail exchange binding uses the <mail-domain> part of a mailbox -specification to determine where mail should be sent. The <local-part> -is not even consulted. [RFC-974] specifies this method in detail, and -should be consulted before attempting to use mail exchange support. - -One of the advantages of this method is that it decouples mail -destination naming from the hosts used to support mail service, at the -cost of another layer of indirection in the lookup function. However, -the addition layer should eliminate the need for complicated "%", "!", -etc encodings in <local-part>. - -The essence of the method is that the <mail-domain> is used as a domain -name to locate type MX RRs which list hosts willing to accept mail for -<mail-domain>, together with preference values which rank the hosts -according to an order specified by the administrators for <mail-domain>. - -In this memo, the <mail-domain> ISI.EDU is used in examples, together -with the hosts VENERA.ISI.EDU and VAXA.ISI.EDU as mail exchanges for -ISI.EDU. If a mailer had a message for Mockapetris@ISI.EDU, it would -route it by looking up MX RRs for ISI.EDU. The MX RRs at ISI.EDU name -VENERA.ISI.EDU and VAXA.ISI.EDU, and type A queries can find the host -addresses. - -8.2. Mailbox binding (Experimental) - -In mailbox binding, the mailer uses the entire mail destination -specification to construct a domain name. The encoded domain name for -the mailbox is used as the QNAME field in a QTYPE=MAILB query. - -Several outcomes are possible for this query: - - - -Mockapetris [Page 48] - -RFC 1035 Domain Implementation and Specification November 1987 - - - 1. The query can return a name error indicating that the mailbox - does not exist as a domain name. - - In the long term, this would indicate that the specified - mailbox doesn't exist. However, until the use of mailbox - binding is universal, this error condition should be - interpreted to mean that the organization identified by the - global part does not support mailbox binding. The - appropriate procedure is to revert to exchange binding at - this point. - - 2. The query can return a Mail Rename (MR) RR. - - The MR RR carries new mailbox specification in its RDATA - field. The mailer should replace the old mailbox with the - new one and retry the operation. - - 3. The query can return a MB RR. - - The MB RR carries a domain name for a host in its RDATA - field. The mailer should deliver the message to that host - via whatever protocol is applicable, e.g., b,SMTP. - - 4. The query can return one or more Mail Group (MG) RRs. - - This condition means that the mailbox was actually a mailing - list or mail group, rather than a single mailbox. Each MG RR - has a RDATA field that identifies a mailbox that is a member - of the group. The mailer should deliver a copy of the - message to each member. - - 5. The query can return a MB RR as well as one or more MG RRs. - - This condition means the the mailbox was actually a mailing - list. The mailer can either deliver the message to the host - specified by the MB RR, which will in turn do the delivery to - all members, or the mailer can use the MG RRs to do the - expansion itself. - -In any of these cases, the response may include a Mail Information -(MINFO) RR. This RR is usually associated with a mail group, but is -legal with a MB. The MINFO RR identifies two mailboxes. One of these -identifies a responsible person for the original mailbox name. This -mailbox should be used for requests to be added to a mail group, etc. -The second mailbox name in the MINFO RR identifies a mailbox that should -receive error messages for mail failures. This is particularly -appropriate for mailing lists when errors in member names should be -reported to a person other than the one who sends a message to the list. - - - -Mockapetris [Page 49] - -RFC 1035 Domain Implementation and Specification November 1987 - - -New fields may be added to this RR in the future. - - -9. REFERENCES and BIBLIOGRAPHY - -[Dyer 87] S. Dyer, F. Hsu, "Hesiod", Project Athena - Technical Plan - Name Service, April 1987, version 1.9. - - Describes the fundamentals of the Hesiod name service. - -[IEN-116] J. Postel, "Internet Name Server", IEN-116, - USC/Information Sciences Institute, August 1979. - - A name service obsoleted by the Domain Name System, but - still in use. - -[Quarterman 86] J. Quarterman, and J. Hoskins, "Notable Computer Networks", - Communications of the ACM, October 1986, volume 29, number - 10. - -[RFC-742] K. Harrenstien, "NAME/FINGER", RFC-742, Network - Information Center, SRI International, December 1977. - -[RFC-768] J. Postel, "User Datagram Protocol", RFC-768, - USC/Information Sciences Institute, August 1980. - -[RFC-793] J. Postel, "Transmission Control Protocol", RFC-793, - USC/Information Sciences Institute, September 1981. - -[RFC-799] D. Mills, "Internet Name Domains", RFC-799, COMSAT, - September 1981. - - Suggests introduction of a hierarchy in place of a flat - name space for the Internet. - -[RFC-805] J. Postel, "Computer Mail Meeting Notes", RFC-805, - USC/Information Sciences Institute, February 1982. - -[RFC-810] E. Feinler, K. Harrenstien, Z. Su, and V. White, "DOD - Internet Host Table Specification", RFC-810, Network - Information Center, SRI International, March 1982. - - Obsolete. See RFC-952. - -[RFC-811] K. Harrenstien, V. White, and E. Feinler, "Hostnames - Server", RFC-811, Network Information Center, SRI - International, March 1982. - - - - -Mockapetris [Page 50] - -RFC 1035 Domain Implementation and Specification November 1987 - - - Obsolete. See RFC-953. - -[RFC-812] K. Harrenstien, and V. White, "NICNAME/WHOIS", RFC-812, - Network Information Center, SRI International, March - 1982. - -[RFC-819] Z. Su, and J. Postel, "The Domain Naming Convention for - Internet User Applications", RFC-819, Network - Information Center, SRI International, August 1982. - - Early thoughts on the design of the domain system. - Current implementation is completely different. - -[RFC-821] J. Postel, "Simple Mail Transfer Protocol", RFC-821, - USC/Information Sciences Institute, August 1980. - -[RFC-830] Z. Su, "A Distributed System for Internet Name Service", - RFC-830, Network Information Center, SRI International, - October 1982. - - Early thoughts on the design of the domain system. - Current implementation is completely different. - -[RFC-882] P. Mockapetris, "Domain names - Concepts and - Facilities," RFC-882, USC/Information Sciences - Institute, November 1983. - - Superceeded by this memo. - -[RFC-883] P. Mockapetris, "Domain names - Implementation and - Specification," RFC-883, USC/Information Sciences - Institute, November 1983. - - Superceeded by this memo. - -[RFC-920] J. Postel and J. Reynolds, "Domain Requirements", - RFC-920, USC/Information Sciences Institute, - October 1984. - - Explains the naming scheme for top level domains. - -[RFC-952] K. Harrenstien, M. Stahl, E. Feinler, "DoD Internet Host - Table Specification", RFC-952, SRI, October 1985. - - Specifies the format of HOSTS.TXT, the host/address - table replaced by the DNS. - - - - - -Mockapetris [Page 51] - -RFC 1035 Domain Implementation and Specification November 1987 - - -[RFC-953] K. Harrenstien, M. Stahl, E. Feinler, "HOSTNAME Server", - RFC-953, SRI, October 1985. - - This RFC contains the official specification of the - hostname server protocol, which is obsoleted by the DNS. - This TCP based protocol accesses information stored in - the RFC-952 format, and is used to obtain copies of the - host table. - -[RFC-973] P. Mockapetris, "Domain System Changes and - Observations", RFC-973, USC/Information Sciences - Institute, January 1986. - - Describes changes to RFC-882 and RFC-883 and reasons for - them. - -[RFC-974] C. Partridge, "Mail routing and the domain system", - RFC-974, CSNET CIC BBN Labs, January 1986. - - Describes the transition from HOSTS.TXT based mail - addressing to the more powerful MX system used with the - domain system. - -[RFC-1001] NetBIOS Working Group, "Protocol standard for a NetBIOS - service on a TCP/UDP transport: Concepts and Methods", - RFC-1001, March 1987. - - This RFC and RFC-1002 are a preliminary design for - NETBIOS on top of TCP/IP which proposes to base NetBIOS - name service on top of the DNS. - -[RFC-1002] NetBIOS Working Group, "Protocol standard for a NetBIOS - service on a TCP/UDP transport: Detailed - Specifications", RFC-1002, March 1987. - -[RFC-1010] J. Reynolds, and J. Postel, "Assigned Numbers", RFC-1010, - USC/Information Sciences Institute, May 1987. - - Contains socket numbers and mnemonics for host names, - operating systems, etc. - -[RFC-1031] W. Lazear, "MILNET Name Domain Transition", RFC-1031, - November 1987. - - Describes a plan for converting the MILNET to the DNS. - -[RFC-1032] M. Stahl, "Establishing a Domain - Guidelines for - Administrators", RFC-1032, November 1987. - - - -Mockapetris [Page 52] - -RFC 1035 Domain Implementation and Specification November 1987 - - - Describes the registration policies used by the NIC to - administer the top level domains and delegate subzones. - -[RFC-1033] M. Lottor, "Domain Administrators Operations Guide", - RFC-1033, November 1987. - - A cookbook for domain administrators. - -[Solomon 82] M. Solomon, L. Landweber, and D. Neuhengen, "The CSNET - Name Server", Computer Networks, vol 6, nr 3, July 1982. - - Describes a name service for CSNET which is independent - from the DNS and DNS use in the CSNET. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Mockapetris [Page 53] - -RFC 1035 Domain Implementation and Specification November 1987 - - -Index - - * 13 - - ; 33, 35 - - <character-string> 35 - <domain-name> 34 - - @ 35 - - \ 35 - - A 12 - - Byte order 8 - - CH 13 - Character case 9 - CLASS 11 - CNAME 12 - Completion 42 - CS 13 - - Hesiod 13 - HINFO 12 - HS 13 - - IN 13 - IN-ADDR.ARPA domain 22 - Inverse queries 40 - - Mailbox names 47 - MB 12 - MD 12 - MF 12 - MG 12 - MINFO 12 - MINIMUM 20 - MR 12 - MX 12 - - NS 12 - NULL 12 - - Port numbers 32 - Primary server 5 - PTR 12, 18 - - - -Mockapetris [Page 54] - -RFC 1035 Domain Implementation and Specification November 1987 - - - QCLASS 13 - QTYPE 12 - - RDATA 12 - RDLENGTH 11 - - Secondary server 5 - SOA 12 - Stub resolvers 7 - - TCP 32 - TXT 12 - TYPE 11 - - UDP 32 - - WKS 12 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Mockapetris [Page 55] - diff --git a/docs/rfc/rfc1413.txt b/docs/rfc/rfc1413.txt deleted file mode 100644 index 17ede58a2..000000000 --- a/docs/rfc/rfc1413.txt +++ /dev/null @@ -1,451 +0,0 @@ - - - - - - -Network Working Group M. St. Johns -Request for Comments: 1413 US Department of Defense -Obsoletes: 931 February 1993 - - - Identification Protocol - -Status of this Memo - - This RFC specifies an IAB standards track protocol for the Internet - community, and requests discussion and suggestions for improvements. - Please refer to the current edition of the "IAB Official Protocol - Standards" for the standardization state and status of this protocol. - Distribution of this memo is unlimited. - -1. INTRODUCTION - - The Identification Protocol (a.k.a., "ident", a.k.a., "the Ident - Protocol") provides a means to determine the identity of a user of a - particular TCP connection. Given a TCP port number pair, it returns - a character string which identifies the owner of that connection on - the server's system. - - The Identification Protocol was formerly called the Authentication - Server Protocol. It has been renamed to better reflect its function. - This document is a product of the TCP Client Identity Protocol - Working Group of the Internet Engineering Task Force (IETF). - -2. OVERVIEW - - This is a connection based application on TCP. A server listens for - TCP connections on TCP port 113 (decimal). Once a connection is - established, the server reads a line of data which specifies the - connection of interest. If it exists, the system dependent user - identifier of the connection of interest is sent as the reply. The - server may then either shut the connection down or it may continue to - read/respond to multiple queries. - - The server should close the connection down after a configurable - amount of time with no queries - a 60-180 second idle timeout is - recommended. The client may close the connection down at any time; - however to allow for network delays the client should wait at least - 30 seconds (or longer) after a query before abandoning the query and - closing the connection. - - - - - - - -St. Johns [Page 1] - -RFC 1413 Identification Protocol February 1993 - - -3. RESTRICTIONS - - Queries are permitted only for fully specified connections. The - query contains the local/foreign port pair -- the local/foreign - address pair used to fully specify the connection is taken from the - local and foreign address of query connection. This means a user on - address A may only query the server on address B about connections - between A and B. - -4. QUERY/RESPONSE FORMAT - - The server accepts simple text query requests of the form: - - <port-on-server> , <port-on-client> - - where <port-on-server> is the TCP port (decimal) on the target (where - the "ident" server is running) system, and <port-on-client> is the - TCP port (decimal) on the source (client) system. - - N.B - If a client on host A wants to ask a server on host B about a - connection specified locally (on the client's machine) as 23, 6191 - (an inbound TELNET connection), the client must actually ask about - 6191, 23 - which is how the connection would be specified on host B. - - For example: - - 6191, 23 - - The response is of the form - - <port-on-server> , <port-on-client> : <resp-type> : <add-info> - - where <port-on-server>,<port-on-client> are the same pair as the - query, <resp-type> is a keyword identifying the type of response, and - <add-info> is context dependent. - - The information returned is that associated with the fully specified - TCP connection identified by <server-address>, <client-address>, - <port-on-server>, <port-on-client>, where <server-address> and - <client-address> are the local and foreign IP addresses of the - querying connection -- i.e., the TCP connection to the Identification - Protocol Server. (<port-on-server> and <port-on-client> are taken - from the query.) - - For example: - - 6193, 23 : USERID : UNIX : stjohns - 6195, 23 : ERROR : NO-USER - - - -St. Johns [Page 2] - -RFC 1413 Identification Protocol February 1993 - - -5. RESPONSE TYPES - -A response can be one of two types: - -USERID - - In this case, <add-info> is a string consisting of an - operating system name (with an optional character set - identifier), followed by ":", followed by an - identification string. - - The character set (if present) is separated from the - operating system name by ",". The character set - identifier is used to indicate the character set of the - identification string. The character set identifier, - if omitted, defaults to "US-ASCII" (see below). - - Permitted operating system names and character set - names are specified in RFC 1340, "Assigned Numbers" or - its successors. - - In addition to those operating system and character set - names specified in "Assigned Numbers" there is one - special case operating system identifier - "OTHER". - - Unless "OTHER" is specified as the operating system - type, the server is expected to return the "normal" - user identification of the owner of this connection. - "Normal" in this context may be taken to mean a string - of characters which uniquely identifies the connection - owner such as a user identifier assigned by the system - administrator and used by such user as a mail - identifier, or as the "user" part of a user/password - pair used to gain access to system resources. When an - operating system is specified (e.g., anything but - "OTHER"), the user identifier is expected to be in a - more or less immediately useful form - e.g., something - that could be used as an argument to "finger" or as a - mail address. - - "OTHER" indicates the identifier is an unformatted - character string consisting of printable characters in - the specified character set. "OTHER" should be - specified if the user identifier does not meet the - constraints of the previous paragraph. Sending an - encrypted audit token, or returning other non-userid - information about a user (such as the real name and - phone number of a user from a UNIX passwd file) are - - - -St. Johns [Page 3] - -RFC 1413 Identification Protocol February 1993 - - - both examples of when "OTHER" should be used. - - Returned user identifiers are expected to be printable - in the character set indicated. - - The identifier is an unformatted octet string - - all - octets are permissible EXCEPT octal 000 (NUL), 012 (LF) - and 015 (CR). N.B. - space characters (040) following the - colon separator ARE part of the identifier string and - may not be ignored. A response string is still - terminated normally by a CR/LF. N.B. A string may be - printable, but is not *necessarily* printable. - -ERROR - - For some reason the port owner could not be determined, <add-info> - tells why. The following are the permitted values of <add-info> and - their meanings: - - INVALID-PORT - - Either the local or foreign port was improperly - specified. This should be returned if either or - both of the port ids were out of range (TCP port - numbers are from 1-65535), negative integers, reals or - in any fashion not recognized as a non-negative - integer. - - NO-USER - - The connection specified by the port pair is not - currently in use or currently not owned by an - identifiable entity. - - HIDDEN-USER - - The server was able to identify the user of this - port, but the information was not returned at the - request of the user. - - UNKNOWN-ERROR - - Can't determine connection owner; reason unknown. - Any error not covered above should return this - error code value. Optionally, this code MAY be - returned in lieu of any other specific error code - if, for example, the server desires to hide - information implied by the return of that error - - - -St. Johns [Page 4] - -RFC 1413 Identification Protocol February 1993 - - - code, or for any other reason. If a server - implements such a feature, it MUST be configurable - and it MUST default to returning the proper error - message. - - Other values may eventually be specified and defined in future - revisions to this document. If an implementer has a need to specify - a non-standard error code, that code must begin with "X". - - In addition, the server is allowed to drop the query connection - without responding. Any premature close (i.e., one where the client - does not receive the EOL, whether graceful or an abort should be - considered to have the same meaning as "ERROR : UNKNOWN-ERROR". - -FORMAL SYNTAX - - <request> ::= <port-pair> <EOL> - - <port-pair> ::= <integer> "," <integer> - - <reply> ::= <reply-text> <EOL> - - <EOL> ::= "015 012" ; CR-LF End of Line Indicator - - <reply-text> ::= <error-reply> | <ident-reply> - - <error-reply> ::= <port-pair> ":" "ERROR" ":" <error-type> - - <ident-reply> ::= <port-pair> ":" "USERID" ":" <opsys-field> - ":" <user-id> - - <error-type> ::= "INVALID-PORT" | "NO-USER" | "UNKNOWN-ERROR" - | "HIDDEN-USER" | <error-token> - - <opsys-field> ::= <opsys> [ "," <charset>] - - <opsys> ::= "OTHER" | "UNIX" | <token> ...etc. - ; (See "Assigned Numbers") - - <charset> ::= "US-ASCII" | ...etc. - ; (See "Assigned Numbers") - - <user-id> ::= <octet-string> - - <token> ::= 1*64<token-characters> ; 1-64 characters - - <error-token> ::= "X"1*63<token-characters> - ; 2-64 chars beginning w/X - - - -St. Johns [Page 5] - -RFC 1413 Identification Protocol February 1993 - - - <integer> ::= 1*5<digit> ; 1-5 digits. - - <digit> ::= "0" | "1" ... "8" | "9" ; 0-9 - - <token-characters> ::= - <Any of these ASCII characters: a-z, A-Z, - - (dash), .!@#$%^&*()_=+.,<>/?"'~`{}[]; > - ; upper and lowercase a-z plus - ; printables minus the colon ":" - ; character. - - <octet-string> ::= 1*512<octet-characters> - - <octet-characters> ::= - <any octet from 00 to 377 (octal) except for - ASCII NUL (000), CR (015) and LF (012)> - -Notes on Syntax: - - 1) To promote interoperability among variant - implementations, with respect to white space the above - syntax is understood to embody the "be conservative in - what you send and be liberal in what you accept" - philosophy. Clients and servers should not generate - unnecessary white space (space and tab characters) but - should accept white space anywhere except within a - token. In parsing responses, white space may occur - anywhere, except within a token. Specifically, any - amount of white space is permitted at the beginning or - end of a line both for queries and responses. This - does not apply for responses that contain a user ID - because everything after the colon after the operating - system type until the terminating CR/LF is taken as - part of the user ID. The terminating CR/LF is NOT - considered part of the user ID. - - 2) The above notwithstanding, servers should restrict the - amount of inter-token white space they send to the - smallest amount reasonable or useful. Clients should - feel free to abort a connection if they receive 1000 - characters without receiving an <EOL>. - - 3) The 512 character limit on user IDs and the 64 - character limit on tokens should be understood to mean - as follows: a) No new token (i.e., OPSYS or ERROR-TYPE) - token will be defined that has a length greater than 64 - and b) a server SHOULD NOT send more than 512 octets of - user ID and a client MUST accept at least 512 octets of - - - -St. Johns [Page 6] - -RFC 1413 Identification Protocol February 1993 - - - user ID. Because of this limitation, a server MUST - return the most significant portion of the user ID in - the first 512 octets. - - 4) The character sets and character set identifiers should - map directly to those defined in or referenced by RFC 1340, - "Assigned Numbers" or its successors. Character set - identifiers only apply to the user identification field - - all other fields will be defined in and must be sent - as US-ASCII. - - 5) Although <user-id> is defined as an <octet-string> - above, it must follow the format and character set - constraints implied by the <opsys-field>; see the - discussion above. - - 6) The character set provides context for the client to - print or store the returned user identification string. - If the client does not recognize or implement the - returned character set, it should handle the returned - identification string as OCTET, but should in addition - store or report the character set. An OCTET string - should be printed, stored or handled in hex notation - (0-9a-f) in addition to any other representation the - client implements - this provides a standard - representation among differing implementations. - -6. Security Considerations - - The information returned by this protocol is at most as trustworthy - as the host providing it OR the organization operating the host. For - example, a PC in an open lab has few if any controls on it to prevent - a user from having this protocol return any identifier the user - wants. Likewise, if the host has been compromised the information - returned may be completely erroneous and misleading. - - The Identification Protocol is not intended as an authorization or - access control protocol. At best, it provides some additional - auditing information with respect to TCP connections. At worst, it - can provide misleading, incorrect, or maliciously incorrect - information. - - The use of the information returned by this protocol for other than - auditing is strongly discouraged. Specifically, using Identification - Protocol information to make access control decisions - either as the - primary method (i.e., no other checks) or as an adjunct to other - methods may result in a weakening of normal host security. - - - - -St. Johns [Page 7] - -RFC 1413 Identification Protocol February 1993 - - - An Identification server may reveal information about users, - entities, objects or processes which might normally be considered - private. An Identification server provides service which is a rough - analog of the CallerID services provided by some phone companies and - many of the same privacy considerations and arguments that apply to - the CallerID service apply to Identification. If you wouldn't run a - "finger" server due to privacy considerations you may not want to run - this protocol. - -7. ACKNOWLEDGEMENTS - - Acknowledgement is given to Dan Bernstein who is primarily - responsible for renewing interest in this protocol and for pointing - out some annoying errors in RFC 931. - -References - - [1] St. Johns, M., "Authentication Server", RFC 931, TPSC, January - 1985. - - [2] Reynolds, J., and J. Postel, "Assigned Numbers", STD 2, RFC 1340, - USC/Information Sciences Institute, July 1992. - -Author's Address - - Michael C. St. Johns - DARPA/CSTO - 3701 N. Fairfax Dr - Arlington, VA 22203 - - Phone: (703) 696-2271 - EMail: stjohns@DARPA.MIL - - - - - - - - - - - - - - - - - - - -St. Johns [Page 8] -
\ No newline at end of file diff --git a/docs/rfc/rfc1459.txt b/docs/rfc/rfc1459.txt deleted file mode 100644 index 09fbf34f7..000000000 --- a/docs/rfc/rfc1459.txt +++ /dev/null @@ -1,3643 +0,0 @@ - - - - - - -Network Working Group J. Oikarinen -Request for Comments: 1459 D. Reed - May 1993 - - - Internet Relay Chat Protocol - -Status of This Memo - - This memo defines an Experimental Protocol for the Internet - community. Discussion and suggestions for improvement are requested. - Please refer to the current edition of the "IAB Official Protocol - Standards" for the standardization state and status of this protocol. - Distribution of this memo is unlimited. - -Abstract - - The IRC protocol was developed over the last 4 years since it was - first implemented as a means for users on a BBS to chat amongst - themselves. Now it supports a world-wide network of servers and - clients, and is stringing to cope with growth. Over the past 2 years, - the average number of users connected to the main IRC network has - grown by a factor of 10. - - The IRC protocol is a text-based protocol, with the simplest client - being any socket program capable of connecting to the server. - -Table of Contents - - 1. INTRODUCTION ............................................... 4 - 1.1 Servers ................................................ 4 - 1.2 Clients ................................................ 5 - 1.2.1 Operators .......................................... 5 - 1.3 Channels ................................................ 5 - 1.3.1 Channel Operators .................................... 6 - 2. THE IRC SPECIFICATION ....................................... 7 - 2.1 Overview ................................................ 7 - 2.2 Character codes ......................................... 7 - 2.3 Messages ................................................ 7 - 2.3.1 Message format in 'pseudo' BNF .................... 8 - 2.4 Numeric replies ......................................... 10 - 3. IRC Concepts ................................................ 10 - 3.1 One-to-one communication ................................ 10 - 3.2 One-to-many ............................................. 11 - 3.2.1 To a list .......................................... 11 - 3.2.2 To a group (channel) ............................... 11 - 3.2.3 To a host/server mask .............................. 12 - 3.3 One to all .............................................. 12 - - - -Oikarinen & Reed [Page 1] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 3.3.1 Client to Client ................................... 12 - 3.3.2 Clients to Server .................................. 12 - 3.3.3 Server to Server ................................... 12 - 4. MESSAGE DETAILS ............................................. 13 - 4.1 Connection Registration ................................. 13 - 4.1.1 Password message ................................... 14 - 4.1.2 Nickname message ................................... 14 - 4.1.3 User message ....................................... 15 - 4.1.4 Server message ..................................... 16 - 4.1.5 Operator message ................................... 17 - 4.1.6 Quit message ....................................... 17 - 4.1.7 Server Quit message ................................ 18 - 4.2 Channel operations ...................................... 19 - 4.2.1 Join message ....................................... 19 - 4.2.2 Part message ....................................... 20 - 4.2.3 Mode message ....................................... 21 - 4.2.3.1 Channel modes ................................. 21 - 4.2.3.2 User modes .................................... 22 - 4.2.4 Topic message ...................................... 23 - 4.2.5 Names message ...................................... 24 - 4.2.6 List message ....................................... 24 - 4.2.7 Invite message ..................................... 25 - 4.2.8 Kick message ....................................... 25 - 4.3 Server queries and commands ............................. 26 - 4.3.1 Version message .................................... 26 - 4.3.2 Stats message ...................................... 27 - 4.3.3 Links message ...................................... 28 - 4.3.4 Time message ....................................... 29 - 4.3.5 Connect message .................................... 29 - 4.3.6 Trace message ...................................... 30 - 4.3.7 Admin message ...................................... 31 - 4.3.8 Info message ....................................... 31 - 4.4 Sending messages ........................................ 32 - 4.4.1 Private messages ................................... 32 - 4.4.2 Notice messages .................................... 33 - 4.5 User-based queries ...................................... 33 - 4.5.1 Who query .......................................... 33 - 4.5.2 Whois query ........................................ 34 - 4.5.3 Whowas message ..................................... 35 - 4.6 Miscellaneous messages .................................. 35 - 4.6.1 Kill message ....................................... 36 - 4.6.2 Ping message ....................................... 37 - 4.6.3 Pong message ....................................... 37 - 4.6.4 Error message ...................................... 38 - 5. OPTIONAL MESSAGES ........................................... 38 - 5.1 Away message ............................................ 38 - 5.2 Rehash command .......................................... 39 - 5.3 Restart command ......................................... 39 - - - -Oikarinen & Reed [Page 2] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 5.4 Summon message .......................................... 40 - 5.5 Users message ........................................... 40 - 5.6 Operwall command ........................................ 41 - 5.7 Userhost message ........................................ 42 - 5.8 Ison message ............................................ 42 - 6. REPLIES ..................................................... 43 - 6.1 Error Replies ........................................... 43 - 6.2 Command responses ....................................... 48 - 6.3 Reserved numerics ....................................... 56 - 7. Client and server authentication ............................ 56 - 8. Current Implementations Details ............................. 56 - 8.1 Network protocol: TCP ................................... 57 - 8.1.1 Support of Unix sockets ............................ 57 - 8.2 Command Parsing ......................................... 57 - 8.3 Message delivery ........................................ 57 - 8.4 Connection 'Liveness' ................................... 58 - 8.5 Establishing a server-client connection ................. 58 - 8.6 Establishing a server-server connection ................. 58 - 8.6.1 State information exchange when connecting ......... 59 - 8.7 Terminating server-client connections ................... 59 - 8.8 Terminating server-server connections ................... 59 - 8.9 Tracking nickname changes ............................... 60 - 8.10 Flood control of clients ............................... 60 - 8.11 Non-blocking lookups ................................... 61 - 8.11.1 Hostname (DNS) lookups ............................ 61 - 8.11.2 Username (Ident) lookups .......................... 61 - 8.12 Configuration file ..................................... 61 - 8.12.1 Allowing clients to connect ....................... 62 - 8.12.2 Operators ......................................... 62 - 8.12.3 Allowing servers to connect ....................... 62 - 8.12.4 Administrivia ..................................... 63 - 8.13 Channel membership ..................................... 63 - 9. Current problems ............................................ 63 - 9.1 Scalability ............................................. 63 - 9.2 Labels .................................................. 63 - 9.2.1 Nicknames .......................................... 63 - 9.2.2 Channels ........................................... 64 - 9.2.3 Servers ............................................ 64 - 9.3 Algorithms .............................................. 64 - 10. Support and availability ................................... 64 - 11. Security Considerations .................................... 65 - 12. Authors' Addresses ......................................... 65 - - - - - - - - - -Oikarinen & Reed [Page 3] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -1. INTRODUCTION - - The IRC (Internet Relay Chat) protocol has been designed over a - number of years for use with text based conferencing. This document - describes the current IRC protocol. - - The IRC protocol has been developed on systems using the TCP/IP - network protocol, although there is no requirement that this remain - the only sphere in which it operates. - - IRC itself is a teleconferencing system, which (through the use of - the client-server model) is well-suited to running on many machines - in a distributed fashion. A typical setup involves a single process - (the server) forming a central point for clients (or other servers) - to connect to, performing the required message delivery/multiplexing - and other functions. - -1.1 Servers - - The server forms the backbone of IRC, providing a point to which - clients may connect to to talk to each other, and a point for other - servers to connect to, forming an IRC network. The only network - configuration allowed for IRC servers is that of a spanning tree [see - Fig. 1] where each server acts as a central node for the rest of the - net it sees. - - - [ Server 15 ] [ Server 13 ] [ Server 14] - / \ / - / \ / - [ Server 11 ] ------ [ Server 1 ] [ Server 12] - / \ / - / \ / - [ Server 2 ] [ Server 3 ] - / \ \ - / \ \ - [ Server 4 ] [ Server 5 ] [ Server 6 ] - / | \ / - / | \ / - / | \____ / - / | \ / - [ Server 7 ] [ Server 8 ] [ Server 9 ] [ Server 10 ] - - : - [ etc. ] - : - - [ Fig. 1. Format of IRC server network ] - - - -Oikarinen & Reed [Page 4] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -1.2 Clients - - A client is anything connecting to a server that is not another - server. Each client is distinguished from other clients by a unique - nickname having a maximum length of nine (9) characters. See the - protocol grammar rules for what may and may not be used in a - nickname. In addition to the nickname, all servers must have the - following information about all clients: the real name of the host - that the client is running on, the username of the client on that - host, and the server to which the client is connected. - -1.2.1 Operators - - To allow a reasonable amount of order to be kept within the IRC - network, a special class of clients (operators) is allowed to perform - general maintenance functions on the network. Although the powers - granted to an operator can be considered as 'dangerous', they are - nonetheless required. Operators should be able to perform basic - network tasks such as disconnecting and reconnecting servers as - needed to prevent long-term use of bad network routing. In - recognition of this need, the protocol discussed herein provides for - operators only to be able to perform such functions. See sections - 4.1.7 (SQUIT) and 4.3.5 (CONNECT). - - A more controversial power of operators is the ability to remove a - user from the connected network by 'force', i.e. operators are able - to close the connection between any client and server. The - justification for this is delicate since its abuse is both - destructive and annoying. For further details on this type of - action, see section 4.6.1 (KILL). - -1.3 Channels - - A channel is a named group of one or more clients which will all - receive messages addressed to that channel. The channel is created - implicitly when the first client joins it, and the channel ceases to - exist when the last client leaves it. While channel exists, any - client can reference the channel using the name of the channel. - - Channels names are strings (beginning with a '&' or '#' character) of - length up to 200 characters. Apart from the the requirement that the - first character being either '&' or '#'; the only restriction on a - channel name is that it may not contain any spaces (' '), a control G - (^G or ASCII 7), or a comma (',' which is used as a list item - separator by the protocol). - - There are two types of channels allowed by this protocol. One is a - distributed channel which is known to all the servers that are - - - -Oikarinen & Reed [Page 5] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - connected to the network. These channels are marked by the first - character being a only clients on the server where it exists may join - it. These are distinguished by a leading '&' character. On top of - these two types, there are the various channel modes available to - alter the characteristics of individual channels. See section 4.2.3 - (MODE command) for more details on this. - - To create a new channel or become part of an existing channel, a user - is required to JOIN the channel. If the channel doesn't exist prior - to joining, the channel is created and the creating user becomes a - channel operator. If the channel already exists, whether or not your - request to JOIN that channel is honoured depends on the current modes - of the channel. For example, if the channel is invite-only, (+i), - then you may only join if invited. As part of the protocol, a user - may be a part of several channels at once, but a limit of ten (10) - channels is recommended as being ample for both experienced and - novice users. See section 8.13 for more information on this. - - If the IRC network becomes disjoint because of a split between two - servers, the channel on each side is only composed of those clients - which are connected to servers on the respective sides of the split, - possibly ceasing to exist on one side of the split. When the split - is healed, the connecting servers announce to each other who they - think is in each channel and the mode of that channel. If the - channel exists on both sides, the JOINs and MODEs are interpreted in - an inclusive manner so that both sides of the new connection will - agree about which clients are in the channel and what modes the - channel has. - -1.3.1 Channel Operators - - The channel operator (also referred to as a "chop" or "chanop") on a - given channel is considered to 'own' that channel. In recognition of - this status, channel operators are endowed with certain powers which - enable them to keep control and some sort of sanity in their channel. - As an owner of a channel, a channel operator is not required to have - reasons for their actions, although if their actions are generally - antisocial or otherwise abusive, it might be reasonable to ask an IRC - operator to intervene, or for the usersjust leave and go elsewhere - and form their own channel. - - The commands which may only be used by channel operators are: - - KICK - Eject a client from the channel - MODE - Change the channel's mode - INVITE - Invite a client to an invite-only channel (mode +i) - TOPIC - Change the channel topic in a mode +t channel - - - - -Oikarinen & Reed [Page 6] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - A channel operator is identified by the '@' symbol next to their - nickname whenever it is associated with a channel (ie replies to the - NAMES, WHO and WHOIS commands). - -2. The IRC Specification - -2.1 Overview - - The protocol as described herein is for use both with server to - server and client to server connections. There are, however, more - restrictions on client connections (which are considered to be - untrustworthy) than on server connections. - -2.2 Character codes - - No specific character set is specified. The protocol is based on a a - set of codes which are composed of eight (8) bits, making up an - octet. Each message may be composed of any number of these octets; - however, some octet values are used for control codes which act as - message delimiters. - - Regardless of being an 8-bit protocol, the delimiters and keywords - are such that protocol is mostly usable from USASCII terminal and a - telnet connection. - - Because of IRC's scandanavian origin, the characters {}| are - considered to be the lower case equivalents of the characters []\, - respectively. This is a critical issue when determining the - equivalence of two nicknames. - -2.3 Messages - - Servers and clients send eachother messages which may or may not - generate a reply. If the message contains a valid command, as - described in later sections, the client should expect a reply as - specified but it is not advised to wait forever for the reply; client - to server and server to server communication is essentially - asynchronous in nature. - - Each IRC message may consist of up to three main parts: the prefix - (optional), the command, and the command parameters (of which there - may be up to 15). The prefix, command, and all parameters are - separated by one (or more) ASCII space character(s) (0x20). - - The presence of a prefix is indicated with a single leading ASCII - colon character (':', 0x3b), which must be the first character of the - message itself. There must be no gap (whitespace) between the colon - and the prefix. The prefix is used by servers to indicate the true - - - -Oikarinen & Reed [Page 7] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - origin of the message. If the prefix is missing from the message, it - is assumed to have originated from the connection from which it was - received. Clients should not use prefix when sending a message from - themselves; if they use a prefix, the only valid prefix is the - registered nickname associated with the client. If the source - identified by the prefix cannot be found from the server's internal - database, or if the source is registered from a different link than - from which the message arrived, the server must ignore the message - silently. - - The command must either be a valid IRC command or a three (3) digit - number represented in ASCII text. - - IRC messages are always lines of characters terminated with a CR-LF - (Carriage Return - Line Feed) pair, and these messages shall not - exceed 512 characters in length, counting all characters including - the trailing CR-LF. Thus, there are 510 characters maximum allowed - for the command and its parameters. There is no provision for - continuation message lines. See section 7 for more details about - current implementations. - -2.3.1 Message format in 'pseudo' BNF - - The protocol messages must be extracted from the contiguous stream of - octets. The current solution is to designate two characters, CR and - LF, as message separators. Empty messages are silently ignored, - which permits use of the sequence CR-LF between messages - without extra problems. - - The extracted message is parsed into the components <prefix>, - <command> and list of parameters matched either by <middle> or - <trailing> components. - - The BNF representation for this is: - - -<message> ::= [':' <prefix> <SPACE> ] <command> <params> <crlf> -<prefix> ::= <servername> | <nick> [ '!' <user> ] [ '@' <host> ] -<command> ::= <letter> { <letter> } | <number> <number> <number> -<SPACE> ::= ' ' { ' ' } -<params> ::= <SPACE> [ ':' <trailing> | <middle> <params> ] - -<middle> ::= <Any *non-empty* sequence of octets not including SPACE - or NUL or CR or LF, the first of which may not be ':'> -<trailing> ::= <Any, possibly *empty*, sequence of octets not including - NUL or CR or LF> - -<crlf> ::= CR LF - - - -Oikarinen & Reed [Page 8] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -NOTES: - - 1) <SPACE> is consists only of SPACE character(s) (0x20). - Specially notice that TABULATION, and all other control - characters are considered NON-WHITE-SPACE. - - 2) After extracting the parameter list, all parameters are equal, - whether matched by <middle> or <trailing>. <Trailing> is just - a syntactic trick to allow SPACE within parameter. - - 3) The fact that CR and LF cannot appear in parameter strings is - just artifact of the message framing. This might change later. - - 4) The NUL character is not special in message framing, and - basically could end up inside a parameter, but as it would - cause extra complexities in normal C string handling. Therefore - NUL is not allowed within messages. - - 5) The last parameter may be an empty string. - - 6) Use of the extended prefix (['!' <user> ] ['@' <host> ]) must - not be used in server to server communications and is only - intended for server to client messages in order to provide - clients with more useful information about who a message is - from without the need for additional queries. - - Most protocol messages specify additional semantics and syntax for - the extracted parameter strings dictated by their position in the - list. For example, many server commands will assume that the first - parameter after the command is the list of targets, which can be - described with: - - <target> ::= <to> [ "," <target> ] - <to> ::= <channel> | <user> '@' <servername> | <nick> | <mask> - <channel> ::= ('#' | '&') <chstring> - <servername> ::= <host> - <host> ::= see RFC 952 [DNS:4] for details on allowed hostnames - <nick> ::= <letter> { <letter> | <number> | <special> } - <mask> ::= ('#' | '$') <chstring> - <chstring> ::= <any 8bit code except SPACE, BELL, NUL, CR, LF and - comma (',')> - - Other parameter syntaxes are: - - <user> ::= <nonwhite> { <nonwhite> } - <letter> ::= 'a' ... 'z' | 'A' ... 'Z' - <number> ::= '0' ... '9' - <special> ::= '-' | '[' | ']' | '\' | '`' | '^' | '{' | '}' - - - -Oikarinen & Reed [Page 9] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - <nonwhite> ::= <any 8bit code except SPACE (0x20), NUL (0x0), CR - (0xd), and LF (0xa)> - -2.4 Numeric replies - - Most of the messages sent to the server generate a reply of some - sort. The most common reply is the numeric reply, used for both - errors and normal replies. The numeric reply must be sent as one - message consisting of the sender prefix, the three digit numeric, and - the target of the reply. A numeric reply is not allowed to originate - from a client; any such messages received by a server are silently - dropped. In all other respects, a numeric reply is just like a normal - message, except that the keyword is made up of 3 numeric digits - rather than a string of letters. A list of different replies is - supplied in section 6. - -3. IRC Concepts. - - This section is devoted to describing the actual concepts behind the - organization of the IRC protocol and how the current - implementations deliver different classes of messages. - - - - 1--\ - A D---4 - 2--/ \ / - B----C - / \ - 3 E - - Servers: A, B, C, D, E Clients: 1, 2, 3, 4 - - [ Fig. 2. Sample small IRC network ] - -3.1 One-to-one communication - - Communication on a one-to-one basis is usually only performed by - clients, since most server-server traffic is not a result of servers - talking only to each other. To provide a secure means for clients to - talk to each other, it is required that all servers be able to send a - message in exactly one direction along the spanning tree in order to - reach any client. The path of a message being delivered is the - shortest path between any two points on the spanning tree. - - The following examples all refer to Figure 2 above. - - - - - -Oikarinen & Reed [Page 10] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -Example 1: - A message between clients 1 and 2 is only seen by server A, which - sends it straight to client 2. - -Example 2: - A message between clients 1 and 3 is seen by servers A & B, and - client 3. No other clients or servers are allowed see the message. - -Example 3: - A message between clients 2 and 4 is seen by servers A, B, C & D - and client 4 only. - -3.2 One-to-many - - The main goal of IRC is to provide a forum which allows easy and - efficient conferencing (one to many conversations). IRC offers - several means to achieve this, each serving its own purpose. - -3.2.1 To a list - - The least efficient style of one-to-many conversation is through - clients talking to a 'list' of users. How this is done is almost - self explanatory: the client gives a list of destinations to which - the message is to be delivered and the server breaks it up and - dispatches a separate copy of the message to each given destination. - This isn't as efficient as using a group since the destination list - is broken up and the dispatch sent without checking to make sure - duplicates aren't sent down each path. - -3.2.2 To a group (channel) - - In IRC the channel has a role equivalent to that of the multicast - group; their existence is dynamic (coming and going as people join - and leave channels) and the actual conversation carried out on a - channel is only sent to servers which are supporting users on a given - channel. If there are multiple users on a server in the same - channel, the message text is sent only once to that server and then - sent to each client on the channel. This action is then repeated for - each client-server combination until the original message has fanned - out and reached each member of the channel. - - The following examples all refer to Figure 2. - -Example 4: - Any channel with 1 client in it. Messages to the channel go to the - server and then nowhere else. - - - - - -Oikarinen & Reed [Page 11] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -Example 5: - 2 clients in a channel. All messages traverse a path as if they - were private messages between the two clients outside a channel. - -Example 6: - Clients 1, 2 and 3 in a channel. All messages to the channel are - sent to all clients and only those servers which must be traversed - by the message if it were a private message to a single client. If - client 1 sends a message, it goes back to client 2 and then via - server B to client 3. - -3.2.3 To a host/server mask - - To provide IRC operators with some mechanism to send messages to a - large body of related users, host and server mask messages are - provided. These messages are sent to users whose host or server - information match that of the mask. The messages are only sent to - locations where users are, in a fashion similar to that of channels. - -3.3 One-to-all - - The one-to-all type of message is better described as a broadcast - message, sent to all clients or servers or both. On a large network - of users and servers, a single message can result in a lot of traffic - being sent over the network in an effort to reach all of the desired - destinations. - - For some messages, there is no option but to broadcast it to all - servers so that the state information held by each server is - reasonably consistent between servers. - -3.3.1 Client-to-Client - - There is no class of message which, from a single message, results in - a message being sent to every other client. - -3.3.2 Client-to-Server - - Most of the commands which result in a change of state information - (such as channel membership, channel mode, user status, etc) must be - sent to all servers by default, and this distribution may not be - changed by the client. - -3.3.3 Server-to-Server. - - While most messages between servers are distributed to all 'other' - servers, this is only required for any message that affects either a - user, channel or server. Since these are the basic items found in - - - -Oikarinen & Reed [Page 12] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - IRC, nearly all messages originating from a server are broadcast to - all other connected servers. - -4. Message details - - On the following pages are descriptions of each message recognized by - the IRC server and client. All commands described in this section - must be implemented by any server for this protocol. - - Where the reply ERR_NOSUCHSERVER is listed, it means that the - <server> parameter could not be found. The server must not send any - other replies after this for that command. - - The server to which a client is connected is required to parse the - complete message, returning any appropriate errors. If the server - encounters a fatal error while parsing a message, an error must be - sent back to the client and the parsing terminated. A fatal error - may be considered to be incorrect command, a destination which is - otherwise unknown to the server (server, nick or channel names fit - this category), not enough parameters or incorrect privileges. - - If a full set of parameters is presented, then each must be checked - for validity and appropriate responses sent back to the client. In - the case of messages which use parameter lists using the comma as an - item separator, a reply must be sent for each item. - - In the examples below, some messages appear using the full format: - - :Name COMMAND parameter list - - Such examples represent a message from "Name" in transit between - servers, where it is essential to include the name of the original - sender of the message so remote servers may send back a reply along - the correct path. - -4.1 Connection Registration - - The commands described here are used to register a connection with an - IRC server as either a user or a server as well as correctly - disconnect. - - A "PASS" command is not required for either client or server - connection to be registered, but it must precede the server message - or the latter of the NICK/USER combination. It is strongly - recommended that all server connections have a password in order to - give some level of security to the actual connections. The - recommended order for a client to register is as follows: - - - - -Oikarinen & Reed [Page 13] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 1. Pass message - 2. Nick message - 3. User message - -4.1.1 Password message - - - Command: PASS - Parameters: <password> - - The PASS command is used to set a 'connection password'. The - password can and must be set before any attempt to register the - connection is made. Currently this requires that clients send a PASS - command before sending the NICK/USER combination and servers *must* - send a PASS command before any SERVER command. The password supplied - must match the one contained in the C/N lines (for servers) or I - lines (for clients). It is possible to send multiple PASS commands - before registering but only the last one sent is used for - verification and it may not be changed once registered. Numeric - Replies: - - ERR_NEEDMOREPARAMS ERR_ALREADYREGISTRED - - Example: - - PASS secretpasswordhere - -4.1.2 Nick message - - Command: NICK - Parameters: <nickname> [ <hopcount> ] - - NICK message is used to give user a nickname or change the previous - one. The <hopcount> parameter is only used by servers to indicate - how far away a nick is from its home server. A local connection has - a hopcount of 0. If supplied by a client, it must be ignored. - - If a NICK message arrives at a server which already knows about an - identical nickname for another client, a nickname collision occurs. - As a result of a nickname collision, all instances of the nickname - are removed from the server's database, and a KILL command is issued - to remove the nickname from all other server's database. If the NICK - message causing the collision was a nickname change, then the - original (old) nick must be removed as well. - - If the server recieves an identical NICK from a client which is - directly connected, it may issue an ERR_NICKCOLLISION to the local - client, drop the NICK command, and not generate any kills. - - - -Oikarinen & Reed [Page 14] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - Numeric Replies: - - ERR_NONICKNAMEGIVEN ERR_ERRONEUSNICKNAME - ERR_NICKNAMEINUSE ERR_NICKCOLLISION - - Example: - - NICK Wiz ; Introducing new nick "Wiz". - - :WiZ NICK Kilroy ; WiZ changed his nickname to Kilroy. - -4.1.3 User message - - Command: USER - Parameters: <username> <hostname> <servername> <realname> - - The USER message is used at the beginning of connection to specify - the username, hostname, servername and realname of s new user. It is - also used in communication between servers to indicate new user - arriving on IRC, since only after both USER and NICK have been - received from a client does a user become registered. - - Between servers USER must to be prefixed with client's NICKname. - Note that hostname and servername are normally ignored by the IRC - server when the USER command comes from a directly connected client - (for security reasons), but they are used in server to server - communication. This means that a NICK must always be sent to a - remote server when a new user is being introduced to the rest of the - network before the accompanying USER is sent. - - It must be noted that realname parameter must be the last parameter, - because it may contain space characters and must be prefixed with a - colon (':') to make sure this is recognised as such. - - Since it is easy for a client to lie about its username by relying - solely on the USER message, the use of an "Identity Server" is - recommended. If the host which a user connects from has such a - server enabled the username is set to that as in the reply from the - "Identity Server". - - Numeric Replies: - - ERR_NEEDMOREPARAMS ERR_ALREADYREGISTRED - - Examples: - - - USER guest tolmoon tolsun :Ronnie Reagan - - - -Oikarinen & Reed [Page 15] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - ; User registering themselves with a - username of "guest" and real name - "Ronnie Reagan". - - - :testnick USER guest tolmoon tolsun :Ronnie Reagan - ; message between servers with the - nickname for which the USER command - belongs to - -4.1.4 Server message - - Command: SERVER - Parameters: <servername> <hopcount> <info> - - The server message is used to tell a server that the other end of a - new connection is a server. This message is also used to pass server - data over whole net. When a new server is connected to net, - information about it be broadcast to the whole network. <hopcount> - is used to give all servers some internal information on how far away - all servers are. With a full server list, it would be possible to - construct a map of the entire server tree, but hostmasks prevent this - from being done. - - The SERVER message must only be accepted from either (a) a connection - which is yet to be registered and is attempting to register as a - server, or (b) an existing connection to another server, in which - case the SERVER message is introducing a new server behind that - server. - - Most errors that occur with the receipt of a SERVER command result in - the connection being terminated by the destination host (target - SERVER). Error replies are usually sent using the "ERROR" command - rather than the numeric since the ERROR command has several useful - properties which make it useful here. - - If a SERVER message is parsed and attempts to introduce a server - which is already known to the receiving server, the connection from - which that message must be closed (following the correct procedures), - since a duplicate route to a server has formed and the acyclic nature - of the IRC tree broken. - - Numeric Replies: - - ERR_ALREADYREGISTRED - - Example: - - - - -Oikarinen & Reed [Page 16] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -SERVER test.oulu.fi 1 :[tolsun.oulu.fi] Experimental server - ; New server test.oulu.fi introducing - itself and attempting to register. The - name in []'s is the hostname for the - host running test.oulu.fi. - - -:tolsun.oulu.fi SERVER csd.bu.edu 5 :BU Central Server - ; Server tolsun.oulu.fi is our uplink - for csd.bu.edu which is 5 hops away. - -4.1.5 Oper - - Command: OPER - Parameters: <user> <password> - - OPER message is used by a normal user to obtain operator privileges. - The combination of <user> and <password> are required to gain - Operator privileges. - - If the client sending the OPER command supplies the correct password - for the given user, the server then informs the rest of the network - of the new operator by issuing a "MODE +o" for the clients nickname. - - The OPER message is client-server only. - - Numeric Replies: - - ERR_NEEDMOREPARAMS RPL_YOUREOPER - ERR_NOOPERHOST ERR_PASSWDMISMATCH - - Example: - - OPER foo bar ; Attempt to register as an operator - using a username of "foo" and "bar" as - the password. - -4.1.6 Quit - - Command: QUIT - Parameters: [<Quit message>] - - A client session is ended with a quit message. The server must close - the connection to a client which sends a QUIT message. If a "Quit - Message" is given, this will be sent instead of the default message, - the nickname. - - When netsplits (disconnecting of two servers) occur, the quit message - - - -Oikarinen & Reed [Page 17] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - is composed of the names of two servers involved, separated by a - space. The first name is that of the server which is still connected - and the second name is that of the server that has become - disconnected. - - If, for some other reason, a client connection is closed without the - client issuing a QUIT command (e.g. client dies and EOF occurs - on socket), the server is required to fill in the quit message with - some sort of message reflecting the nature of the event which - caused it to happen. - - Numeric Replies: - - None. - - Examples: - - QUIT :Gone to have lunch ; Preferred message format. - -4.1.7 Server quit message - - Command: SQUIT - Parameters: <server> <comment> - - The SQUIT message is needed to tell about quitting or dead servers. - If a server wishes to break the connection to another server it must - send a SQUIT message to the other server, using the the name of the - other server as the server parameter, which then closes its - connection to the quitting server. - - This command is also available operators to help keep a network of - IRC servers connected in an orderly fashion. Operators may also - issue an SQUIT message for a remote server connection. In this case, - the SQUIT must be parsed by each server inbetween the operator and - the remote server, updating the view of the network held by each - server as explained below. - - The <comment> should be supplied by all operators who execute a SQUIT - for a remote server (that is not connected to the server they are - currently on) so that other operators are aware for the reason of - this action. The <comment> is also filled in by servers which may - place an error or similar message here. - - Both of the servers which are on either side of the connection being - closed are required to to send out a SQUIT message (to all its other - server connections) for all other servers which are considered to be - behind that link. - - - - -Oikarinen & Reed [Page 18] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - Similarly, a QUIT message must be sent to the other connected servers - rest of the network on behalf of all clients behind that link. In - addition to this, all channel members of a channel which lost a - member due to the split must be sent a QUIT message. - - If a server connection is terminated prematurely (e.g. the server on - the other end of the link died), the server which detects - this disconnection is required to inform the rest of the network - that the connection has closed and fill in the comment field - with something appropriate. - - Numeric replies: - - ERR_NOPRIVILEGES ERR_NOSUCHSERVER - - Example: - - SQUIT tolsun.oulu.fi :Bad Link ? ; the server link tolson.oulu.fi has - been terminated because of "Bad Link". - - :Trillian SQUIT cm22.eng.umd.edu :Server out of control - ; message from Trillian to disconnect - "cm22.eng.umd.edu" from the net - because "Server out of control". - -4.2 Channel operations - - This group of messages is concerned with manipulating channels, their - properties (channel modes), and their contents (typically clients). - In implementing these, a number of race conditions are inevitable - when clients at opposing ends of a network send commands which will - ultimately clash. It is also required that servers keep a nickname - history to ensure that wherever a <nick> parameter is given, the - server check its history in case it has recently been changed. - -4.2.1 Join message - - Command: JOIN - Parameters: <channel>{,<channel>} [<key>{,<key>}] - - The JOIN command is used by client to start listening a specific - channel. Whether or not a client is allowed to join a channel is - checked only by the server the client is connected to; all other - servers automatically add the user to the channel when it is received - from other servers. The conditions which affect this are as follows: - - 1. the user must be invited if the channel is invite-only; - - - - -Oikarinen & Reed [Page 19] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 2. the user's nick/username/hostname must not match any - active bans; - - 3. the correct key (password) must be given if it is set. - - These are discussed in more detail under the MODE command (see - section 4.2.3 for more details). - - Once a user has joined a channel, they receive notice about all - commands their server receives which affect the channel. This - includes MODE, KICK, PART, QUIT and of course PRIVMSG/NOTICE. The - JOIN command needs to be broadcast to all servers so that each server - knows where to find the users who are on the channel. This allows - optimal delivery of PRIVMSG/NOTICE messages to the channel. - - If a JOIN is successful, the user is then sent the channel's topic - (using RPL_TOPIC) and the list of users who are on the channel (using - RPL_NAMREPLY), which must include the user joining. - - Numeric Replies: - - ERR_NEEDMOREPARAMS ERR_BANNEDFROMCHAN - ERR_INVITEONLYCHAN ERR_BADCHANNELKEY - ERR_CHANNELISFULL ERR_BADCHANMASK - ERR_NOSUCHCHANNEL ERR_TOOMANYCHANNELS - RPL_TOPIC - - Examples: - - JOIN #foobar ; join channel #foobar. - - JOIN &foo fubar ; join channel &foo using key "fubar". - - JOIN #foo,&bar fubar ; join channel #foo using key "fubar" - and &bar using no key. - - JOIN #foo,#bar fubar,foobar ; join channel #foo using key "fubar". - and channel #bar using key "foobar". - - JOIN #foo,#bar ; join channels #foo and #bar. - - :WiZ JOIN #Twilight_zone ; JOIN message from WiZ - -4.2.2 Part message - - Command: PART - Parameters: <channel>{,<channel>} - - - - -Oikarinen & Reed [Page 20] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - The PART message causes the client sending the message to be removed - from the list of active users for all given channels listed in the - parameter string. - - Numeric Replies: - - ERR_NEEDMOREPARAMS ERR_NOSUCHCHANNEL - ERR_NOTONCHANNEL - - Examples: - - PART #twilight_zone ; leave channel "#twilight_zone" - - PART #oz-ops,&group5 ; leave both channels "&group5" and - "#oz-ops". - -4.2.3 Mode message - - Command: MODE - - The MODE command is a dual-purpose command in IRC. It allows both - usernames and channels to have their mode changed. The rationale for - this choice is that one day nicknames will be obsolete and the - equivalent property will be the channel. - - When parsing MODE messages, it is recommended that the entire message - be parsed first and then the changes which resulted then passed on. - -4.2.3.1 Channel modes - - Parameters: <channel> {[+|-]|o|p|s|i|t|n|b|v} [<limit>] [<user>] - [<ban mask>] - - The MODE command is provided so that channel operators may change the - characteristics of `their' channel. It is also required that servers - be able to change channel modes so that channel operators may be - created. - - The various modes available for channels are as follows: - - o - give/take channel operator privileges; - p - private channel flag; - s - secret channel flag; - i - invite-only channel flag; - t - topic settable by channel operator only flag; - n - no messages to channel from clients on the outside; - m - moderated channel; - l - set the user limit to channel; - - - -Oikarinen & Reed [Page 21] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - b - set a ban mask to keep users out; - v - give/take the ability to speak on a moderated channel; - k - set a channel key (password). - - When using the 'o' and 'b' options, a restriction on a total of three - per mode command has been imposed. That is, any combination of 'o' - and - -4.2.3.2 User modes - - Parameters: <nickname> {[+|-]|i|w|s|o} - - The user MODEs are typically changes which affect either how the - client is seen by others or what 'extra' messages the client is sent. - A user MODE command may only be accepted if both the sender of the - message and the nickname given as a parameter are both the same. - - The available modes are as follows: - - i - marks a users as invisible; - s - marks a user for receipt of server notices; - w - user receives wallops; - o - operator flag. - - Additional modes may be available later on. - - If a user attempts to make themselves an operator using the "+o" - flag, the attempt should be ignored. There is no restriction, - however, on anyone `deopping' themselves (using "-o"). Numeric - Replies: - - ERR_NEEDMOREPARAMS RPL_CHANNELMODEIS - ERR_CHANOPRIVSNEEDED ERR_NOSUCHNICK - ERR_NOTONCHANNEL ERR_KEYSET - RPL_BANLIST RPL_ENDOFBANLIST - ERR_UNKNOWNMODE ERR_NOSUCHCHANNEL - - ERR_USERSDONTMATCH RPL_UMODEIS - ERR_UMODEUNKNOWNFLAG - - Examples: - - Use of Channel Modes: - -MODE #Finnish +im ; Makes #Finnish channel moderated and - 'invite-only'. - -MODE #Finnish +o Kilroy ; Gives 'chanop' privileges to Kilroy on - - - -Oikarinen & Reed [Page 22] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - channel #Finnish. - -MODE #Finnish +v Wiz ; Allow WiZ to speak on #Finnish. - -MODE #Fins -s ; Removes 'secret' flag from channel - #Fins. - -MODE #42 +k oulu ; Set the channel key to "oulu". - -MODE #eu-opers +l 10 ; Set the limit for the number of users - on channel to 10. - -MODE &oulu +b ; list ban masks set for channel. - -MODE &oulu +b *!*@* ; prevent all users from joining. - -MODE &oulu +b *!*@*.edu ; prevent any user from a hostname - matching *.edu from joining. - - Use of user Modes: - -:MODE WiZ -w ; turns reception of WALLOPS messages - off for WiZ. - -:Angel MODE Angel +i ; Message from Angel to make themselves - invisible. - -MODE WiZ -o ; WiZ 'deopping' (removing operator - status). The plain reverse of this - command ("MODE WiZ +o") must not be - allowed from users since would bypass - the OPER command. - -4.2.4 Topic message - - Command: TOPIC - Parameters: <channel> [<topic>] - - The TOPIC message is used to change or view the topic of a channel. - The topic for channel <channel> is returned if there is no <topic> - given. If the <topic> parameter is present, the topic for that - channel will be changed, if the channel modes permit this action. - - Numeric Replies: - - ERR_NEEDMOREPARAMS ERR_NOTONCHANNEL - RPL_NOTOPIC RPL_TOPIC - ERR_CHANOPRIVSNEEDED - - - -Oikarinen & Reed [Page 23] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - Examples: - - :Wiz TOPIC #test :New topic ;User Wiz setting the topic. - - TOPIC #test :another topic ;set the topic on #test to "another - topic". - - TOPIC #test ; check the topic for #test. - -4.2.5 Names message - - Command: NAMES - Parameters: [<channel>{,<channel>}] - - By using the NAMES command, a user can list all nicknames that are - visible to them on any channel that they can see. Channel names - which they can see are those which aren't private (+p) or secret (+s) - or those which they are actually on. The <channel> parameter - specifies which channel(s) to return information about if valid. - There is no error reply for bad channel names. - - If no <channel> parameter is given, a list of all channels and their - occupants is returned. At the end of this list, a list of users who - are visible but either not on any channel or not on a visible channel - are listed as being on `channel' "*". - - Numerics: - - RPL_NAMREPLY RPL_ENDOFNAMES - - Examples: - - NAMES #twilight_zone,#42 ; list visible users on #twilight_zone - and #42 if the channels are visible to - you. - - NAMES ; list all visible channels and users - -4.2.6 List message - - Command: LIST - Parameters: [<channel>{,<channel>} [<server>]] - - The list message is used to list channels and their topics. If the - <channel> parameter is used, only the status of that channel - is displayed. Private channels are listed (without their - topics) as channel "Prv" unless the client generating the query is - actually on that channel. Likewise, secret channels are not listed - - - -Oikarinen & Reed [Page 24] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - at all unless the client is a member of the channel in question. - - Numeric Replies: - - ERR_NOSUCHSERVER RPL_LISTSTART - RPL_LIST RPL_LISTEND - - Examples: - - LIST ; List all channels. - - LIST #twilight_zone,#42 ; List channels #twilight_zone and #42 - -4.2.7 Invite message - - Command: INVITE - Parameters: <nickname> <channel> - - The INVITE message is used to invite users to a channel. The - parameter <nickname> is the nickname of the person to be invited to - the target channel <channel>. There is no requirement that the - channel the target user is being invited to must exist or be a valid - channel. To invite a user to a channel which is invite only (MODE - +i), the client sending the invite must be recognised as being a - channel operator on the given channel. - - Numeric Replies: - - ERR_NEEDMOREPARAMS ERR_NOSUCHNICK - ERR_NOTONCHANNEL ERR_USERONCHANNEL - ERR_CHANOPRIVSNEEDED - RPL_INVITING RPL_AWAY - - Examples: - - :Angel INVITE Wiz #Dust ; User Angel inviting WiZ to channel - #Dust - - INVITE Wiz #Twilight_Zone ; Command to invite WiZ to - #Twilight_zone - -4.2.8 Kick command - - Command: KICK - Parameters: <channel> <user> [<comment>] - - The KICK command can be used to forcibly remove a user from a - channel. It 'kicks them out' of the channel (forced PART). - - - -Oikarinen & Reed [Page 25] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - Only a channel operator may kick another user out of a channel. - Each server that receives a KICK message checks that it is valid - (ie the sender is actually a channel operator) before removing - the victim from the channel. - - Numeric Replies: - - ERR_NEEDMOREPARAMS ERR_NOSUCHCHANNEL - ERR_BADCHANMASK ERR_CHANOPRIVSNEEDED - ERR_NOTONCHANNEL - - Examples: - -KICK &Melbourne Matthew ; Kick Matthew from &Melbourne - -KICK #Finnish John :Speaking English - ; Kick John from #Finnish using - "Speaking English" as the reason - (comment). - -:WiZ KICK #Finnish John ; KICK message from WiZ to remove John - from channel #Finnish - -NOTE: - It is possible to extend the KICK command parameters to the -following: - -<channel>{,<channel>} <user>{,<user>} [<comment>] - -4.3 Server queries and commands - - The server query group of commands has been designed to return - information about any server which is connected to the network. All - servers connected must respond to these queries and respond - correctly. Any invalid response (or lack thereof) must be considered - a sign of a broken server and it must be disconnected/disabled as - soon as possible until the situation is remedied. - - In these queries, where a parameter appears as "<server>", it will - usually mean it can be a nickname or a server or a wildcard name of - some sort. For each parameter, however, only one query and set of - replies is to be generated. - -4.3.1 Version message - - Command: VERSION - Parameters: [<server>] - - - - -Oikarinen & Reed [Page 26] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - The VERSION message is used to query the version of the server - program. An optional parameter <server> is used to query the version - of the server program which a client is not directly connected to. - - Numeric Replies: - - ERR_NOSUCHSERVER RPL_VERSION - - Examples: - - :Wiz VERSION *.se ; message from Wiz to check the version - of a server matching "*.se" - - VERSION tolsun.oulu.fi ; check the version of server - "tolsun.oulu.fi". - -4.3.2 Stats message - - Command: STATS - Parameters: [<query> [<server>]] - - The stats message is used to query statistics of certain server. If - <server> parameter is omitted, only the end of stats reply is sent - back. The implementation of this command is highly dependent on the - server which replies, although the server must be able to supply - information as described by the queries below (or similar). - - A query may be given by any single letter which is only checked by - the destination server (if given as the <server> parameter) and is - otherwise passed on by intermediate servers, ignored and unaltered. - The following queries are those found in the current IRC - implementation and provide a large portion of the setup information - for that server. Although these may not be supported in the same way - by other versions, all servers should be able to supply a valid reply - to a STATS query which is consistent with the reply formats currently - used and the purpose of the query. - - The currently supported queries are: - - c - returns a list of servers which the server may connect - to or allow connections from; - h - returns a list of servers which are either forced to be - treated as leaves or allowed to act as hubs; - i - returns a list of hosts which the server allows a client - to connect from; - k - returns a list of banned username/hostname combinations - for that server; - l - returns a list of the server's connections, showing how - - - -Oikarinen & Reed [Page 27] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - long each connection has been established and the traffic - over that connection in bytes and messages for each - direction; - m - returns a list of commands supported by the server and - the usage count for each if the usage count is non zero; - o - returns a list of hosts from which normal clients may - become operators; - y - show Y (Class) lines from server's configuration file; - u - returns a string showing how long the server has been up. - - Numeric Replies: - - ERR_NOSUCHSERVER - RPL_STATSCLINE RPL_STATSNLINE - RPL_STATSILINE RPL_STATSKLINE - RPL_STATSQLINE RPL_STATSLLINE - RPL_STATSLINKINFO RPL_STATSUPTIME - RPL_STATSCOMMANDS RPL_STATSOLINE - RPL_STATSHLINE RPL_ENDOFSTATS - - Examples: - -STATS m ; check the command usage for the server - you are connected to - -:Wiz STATS c eff.org ; request by WiZ for C/N line - information from server eff.org - -4.3.3 Links message - - Command: LINKS - Parameters: [[<remote server>] <server mask>] - - With LINKS, a user can list all servers which are known by the server - answering the query. The returned list of servers must match the - mask, or if no mask is given, the full list is returned. - - If <remote server> is given in addition to <server mask>, the LINKS - command is forwarded to the first server found that matches that name - (if any), and that server is then required to answer the query. - - Numeric Replies: - - ERR_NOSUCHSERVER - RPL_LINKS RPL_ENDOFLINKS - - Examples: - - - - -Oikarinen & Reed [Page 28] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -LINKS *.au ; list all servers which have a name - that matches *.au; - -:WiZ LINKS *.bu.edu *.edu ; LINKS message from WiZ to the first - server matching *.edu for a list of - servers matching *.bu.edu. - -4.3.4 Time message - - Command: TIME - Parameters: [<server>] - - The time message is used to query local time from the specified - server. If the server parameter is not given, the server handling the - command must reply to the query. - - Numeric Replies: - - ERR_NOSUCHSERVER RPL_TIME - - Examples: - - TIME tolsun.oulu.fi ; check the time on the server - "tolson.oulu.fi" - - Angel TIME *.au ; user angel checking the time on a - server matching "*.au" - -4.3.5 Connect message - - Command: CONNECT - Parameters: <target server> [<port> [<remote server>]] - - The CONNECT command can be used to force a server to try to establish - a new connection to another server immediately. CONNECT is a - privileged command and is to be available only to IRC Operators. If - a remote server is given then the CONNECT attempt is made by that - server to <target server> and <port>. - - Numeric Replies: - - ERR_NOSUCHSERVER ERR_NOPRIVILEGES - ERR_NEEDMOREPARAMS - - Examples: - -CONNECT tolsun.oulu.fi ; Attempt to connect a server to - tolsun.oulu.fi - - - -Oikarinen & Reed [Page 29] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -:WiZ CONNECT eff.org 6667 csd.bu.edu - ; CONNECT attempt by WiZ to get servers - eff.org and csd.bu.edu connected on port - 6667. - -4.3.6 Trace message - - Command: TRACE - Parameters: [<server>] - - TRACE command is used to find the route to specific server. Each - server that processes this message must tell the sender about it by - sending a reply indicating it is a pass-through link, forming a chain - of replies similar to that gained from using "traceroute". After - sending this reply back, it must then send the TRACE message to the - next server until given server is reached. If the <server> parameter - is omitted, it is recommended that TRACE command send a message to - the sender telling which servers the current server has direct - connection to. - - If the destination given by "<server>" is an actual server, then the - destination server is required to report all servers and users which - are connected to it, although only operators are permitted to see - users present. If the destination given by <server> is a nickname, - they only a reply for that nickname is given. - - Numeric Replies: - - ERR_NOSUCHSERVER - - If the TRACE message is destined for another server, all intermediate - servers must return a RPL_TRACELINK reply to indicate that the TRACE - passed through it and where its going next. - - RPL_TRACELINK - A TRACE reply may be composed of any number of the following numeric - replies. - - RPL_TRACECONNECTING RPL_TRACEHANDSHAKE - RPL_TRACEUNKNOWN RPL_TRACEOPERATOR - RPL_TRACEUSER RPL_TRACESERVER - RPL_TRACESERVICE RPL_TRACENEWTYPE - RPL_TRACECLASS - - Examples: - -TRACE *.oulu.fi ; TRACE to a server matching *.oulu.fi - - - - -Oikarinen & Reed [Page 30] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -:WiZ TRACE AngelDust ; TRACE issued by WiZ to nick AngelDust - -4.3.7 Admin command - - Command: ADMIN - Parameters: [<server>] - - The admin message is used to find the name of the administrator of - the given server, or current server if <server> parameter is omitted. - Each server must have the ability to forward ADMIN messages to other - servers. - - Numeric Replies: - - ERR_NOSUCHSERVER - RPL_ADMINME RPL_ADMINLOC1 - RPL_ADMINLOC2 RPL_ADMINEMAIL - - Examples: - - ADMIN tolsun.oulu.fi ; request an ADMIN reply from - tolsun.oulu.fi - - :WiZ ADMIN *.edu ; ADMIN request from WiZ for first - server found to match *.edu. - -4.3.8 Info command - - Command: INFO - Parameters: [<server>] - - The INFO command is required to return information which describes - the server: its version, when it was compiled, the patchlevel, when - it was started, and any other miscellaneous information which may be - considered to be relevant. - - Numeric Replies: - - ERR_NOSUCHSERVER - RPL_INFO RPL_ENDOFINFO - - Examples: - - INFO csd.bu.edu ; request an INFO reply from - csd.bu.edu - - :Avalon INFO *.fi ; INFO request from Avalon for first - server found to match *.fi. - - - -Oikarinen & Reed [Page 31] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - INFO Angel ; request info from the server that - Angel is connected to. - -4.4 Sending messages - - The main purpose of the IRC protocol is to provide a base for clients - to communicate with each other. PRIVMSG and NOTICE are the only - messages available which actually perform delivery of a text message - from one client to another - the rest just make it possible and try - to ensure it happens in a reliable and structured manner. - -4.4.1 Private messages - - Command: PRIVMSG - Parameters: <receiver>{,<receiver>} <text to be sent> - - PRIVMSG is used to send private messages between users. <receiver> - is the nickname of the receiver of the message. <receiver> can also - be a list of names or channels separated with commas. - - The <receiver> parameter may also me a host mask (#mask) or server - mask ($mask). In both cases the server will only send the PRIVMSG - to those who have a server or host matching the mask. The mask must - have at least 1 (one) "." in it and no wildcards following the - last ".". This requirement exists to prevent people sending messages - to "#*" or "$*", which would broadcast to all users; from - experience, this is abused more than used responsibly and properly. - Wildcards are the '*' and '?' characters. This extension to - the PRIVMSG command is only available to Operators. - - Numeric Replies: - - ERR_NORECIPIENT ERR_NOTEXTTOSEND - ERR_CANNOTSENDTOCHAN ERR_NOTOPLEVEL - ERR_WILDTOPLEVEL ERR_TOOMANYTARGETS - ERR_NOSUCHNICK - RPL_AWAY - - Examples: - -:Angel PRIVMSG Wiz :Hello are you receiving this message ? - ; Message from Angel to Wiz. - -PRIVMSG Angel :yes I'm receiving it !receiving it !'u>(768u+1n) .br ; - Message to Angel. - -PRIVMSG jto@tolsun.oulu.fi :Hello ! - ; Message to a client on server - - - -Oikarinen & Reed [Page 32] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - tolsun.oulu.fi with username of "jto". - -PRIVMSG $*.fi :Server tolsun.oulu.fi rebooting. - ; Message to everyone on a server which - has a name matching *.fi. - -PRIVMSG #*.edu :NSFNet is undergoing work, expect interruptions - ; Message to all users who come from a - host which has a name matching *.edu. - -4.4.2 Notice - - Command: NOTICE - Parameters: <nickname> <text> - - The NOTICE message is used similarly to PRIVMSG. The difference - between NOTICE and PRIVMSG is that automatic replies must never be - sent in response to a NOTICE message. This rule applies to servers - too - they must not send any error reply back to the client on - receipt of a notice. The object of this rule is to avoid loops - between a client automatically sending something in response to - something it received. This is typically used by automatons (clients - with either an AI or other interactive program controlling their - actions) which are always seen to be replying lest they end up in a - loop with another automaton. - - See PRIVMSG for more details on replies and examples. - -4.5 User based queries - - User queries are a group of commands which are primarily concerned - with finding details on a particular user or group users. When using - wildcards with any of these commands, if they match, they will only - return information on users who are 'visible' to you. The visibility - of a user is determined as a combination of the user's mode and the - common set of channels you are both on. - -4.5.1 Who query - - Command: WHO - Parameters: [<name> [<o>]] - - The WHO message is used by a client to generate a query which returns - a list of information which 'matches' the <name> parameter given by - the client. In the absence of the <name> parameter, all visible - (users who aren't invisible (user mode +i) and who don't have a - common channel with the requesting client) are listed. The same - result can be achieved by using a <name> of "0" or any wildcard which - - - -Oikarinen & Reed [Page 33] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - will end up matching every entry possible. - - The <name> passed to WHO is matched against users' host, server, real - name and nickname if the channel <name> cannot be found. - - If the "o" parameter is passed only operators are returned according - to the name mask supplied. - - Numeric Replies: - - ERR_NOSUCHSERVER - RPL_WHOREPLY RPL_ENDOFWHO - - Examples: - - WHO *.fi ; List all users who match against - "*.fi". - - WHO jto* o ; List all users with a match against - "jto*" if they are an operator. - -4.5.2 Whois query - - Command: WHOIS - Parameters: [<server>] <nickmask>[,<nickmask>[,...]] - - This message is used to query information about particular user. The - server will answer this message with several numeric messages - indicating different statuses of each user which matches the nickmask - (if you are entitled to see them). If no wildcard is present in the - <nickmask>, any information about that nick which you are allowed to - see is presented. A comma (',') separated list of nicknames may be - given. - - The latter version sends the query to a specific server. It is - useful if you want to know how long the user in question has been - idle as only local server (ie. the server the user is directly - connected to) knows that information, while everything else is - globally known. - - Numeric Replies: - - ERR_NOSUCHSERVER ERR_NONICKNAMEGIVEN - RPL_WHOISUSER RPL_WHOISCHANNELS - RPL_WHOISCHANNELS RPL_WHOISSERVER - RPL_AWAY RPL_WHOISOPERATOR - RPL_WHOISIDLE ERR_NOSUCHNICK - RPL_ENDOFWHOIS - - - -Oikarinen & Reed [Page 34] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - Examples: - - WHOIS wiz ; return available user information - about nick WiZ - - WHOIS eff.org trillian ; ask server eff.org for user - information about trillian - -4.5.3 Whowas - - Command: WHOWAS - Parameters: <nickname> [<count> [<server>]] - - Whowas asks for information about a nickname which no longer exists. - This may either be due to a nickname change or the user leaving IRC. - In response to this query, the server searches through its nickname - history, looking for any nicks which are lexically the same (no wild - card matching here). The history is searched backward, returning the - most recent entry first. If there are multiple entries, up to - <count> replies will be returned (or all of them if no <count> - parameter is given). If a non-positive number is passed as being - <count>, then a full search is done. - - Numeric Replies: - - ERR_NONICKNAMEGIVEN ERR_WASNOSUCHNICK - RPL_WHOWASUSER RPL_WHOISSERVER - RPL_ENDOFWHOWAS - - Examples: - - WHOWAS Wiz ; return all information in the nick - history about nick "WiZ"; - - WHOWAS Mermaid 9 ; return at most, the 9 most recent - entries in the nick history for - "Mermaid"; - - WHOWAS Trillian 1 *.edu ; return the most recent history for - "Trillian" from the first server found - to match "*.edu". - -4.6 Miscellaneous messages - - Messages in this category do not fit into any of the above categories - but are nonetheless still a part of and required by the protocol. - - - - - -Oikarinen & Reed [Page 35] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -4.6.1 Kill message - - Command: KILL - Parameters: <nickname> <comment> - - The KILL message is used to cause a client-server connection to be - closed by the server which has the actual connection. KILL is used - by servers when they encounter a duplicate entry in the list of valid - nicknames and is used to remove both entries. It is also available - to operators. - - Clients which have automatic reconnect algorithms effectively make - this command useless since the disconnection is only brief. It does - however break the flow of data and can be used to stop large amounts - of being abused, any user may elect to receive KILL messages - generated for others to keep an 'eye' on would be trouble spots. - - In an arena where nicknames are required to be globally unique at all - times, KILL messages are sent whenever 'duplicates' are detected - (that is an attempt to register two users with the same nickname) in - the hope that both of them will disappear and only 1 reappear. - - The comment given must reflect the actual reason for the KILL. For - server-generated KILLs it usually is made up of details concerning - the origins of the two conflicting nicknames. For users it is left - up to them to provide an adequate reason to satisfy others who see - it. To prevent/discourage fake KILLs from being generated to hide - the identify of the KILLer, the comment also shows a 'kill-path' - which is updated by each server it passes through, each prepending - its name to the path. - - Numeric Replies: - - ERR_NOPRIVILEGES ERR_NEEDMOREPARAMS - ERR_NOSUCHNICK ERR_CANTKILLSERVER - - - KILL David (csd.bu.edu <- tolsun.oulu.fi) - ; Nickname collision between csd.bu.edu - and tolson.oulu.fi - - - NOTE: - It is recommended that only Operators be allowed to kill other users - with KILL message. In an ideal world not even operators would need - to do this and it would be left to servers to deal with. - - - - - -Oikarinen & Reed [Page 36] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -4.6.2 Ping message - - Command: PING - Parameters: <server1> [<server2>] - - The PING message is used to test the presence of an active client at - the other end of the connection. A PING message is sent at regular - intervals if no other activity detected coming from a connection. If - a connection fails to respond to a PING command within a set amount - of time, that connection is closed. - - Any client which receives a PING message must respond to <server1> - (server which sent the PING message out) as quickly as possible with - an appropriate PONG message to indicate it is still there and alive. - Servers should not respond to PING commands but rely on PINGs from - the other end of the connection to indicate the connection is alive. - If the <server2> parameter is specified, the PING message gets - forwarded there. - - Numeric Replies: - - ERR_NOORIGIN ERR_NOSUCHSERVER - - Examples: - - PING tolsun.oulu.fi ; server sending a PING message to - another server to indicate it is still - alive. - - PING WiZ ; PING message being sent to nick WiZ - -4.6.3 Pong message - - Command: PONG - Parameters: <daemon> [<daemon2>] - - PONG message is a reply to ping message. If parameter <daemon2> is - given this message must be forwarded to given daemon. The <daemon> - parameter is the name of the daemon who has responded to PING message - and generated this message. - - Numeric Replies: - - ERR_NOORIGIN ERR_NOSUCHSERVER - - Examples: - - PONG csd.bu.edu tolsun.oulu.fi ; PONG message from csd.bu.edu to - - - -Oikarinen & Reed [Page 37] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - tolsun.oulu.fi - -4.6.4 Error - - Command: ERROR - Parameters: <error message> - - The ERROR command is for use by servers when reporting a serious or - fatal error to its operators. It may also be sent from one server to - another but must not be accepted from any normal unknown clients. - - An ERROR message is for use for reporting errors which occur with a - server-to-server link only. An ERROR message is sent to the server - at the other end (which sends it to all of its connected operators) - and to all operators currently connected. It is not to be passed - onto any other servers by a server if it is received from a server. - - When a server sends a received ERROR message to its operators, the - message should be encapsulated inside a NOTICE message, indicating - that the client was not responsible for the error. - - Numerics: - - None. - - Examples: - - ERROR :Server *.fi already exists; ERROR message to the other server - which caused this error. - - NOTICE WiZ :ERROR from csd.bu.edu -- Server *.fi already exists - ; Same ERROR message as above but sent - to user WiZ on the other server. - -5. OPTIONALS - - This section describes OPTIONAL messages. They are not required in a - working server implementation of the protocol described herein. In - the absence of the option, an error reply message must be generated - or an unknown command error. If the message is destined for another - server to answer then it must be passed on (elementary parsing - required) The allocated numerics for this are listed with the - messages below. - -5.1 Away - - Command: AWAY - Parameters: [message] - - - -Oikarinen & Reed [Page 38] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - With the AWAY message, clients can set an automatic reply string for - any PRIVMSG commands directed at them (not to a channel they are on). - The automatic reply is sent by the server to client sending the - PRIVMSG command. The only replying server is the one to which the - sending client is connected to. - - The AWAY message is used either with one parameter (to set an AWAY - message) or with no parameters (to remove the AWAY message). - - Numeric Replies: - - RPL_UNAWAY RPL_NOWAWAY - - Examples: - - AWAY :Gone to lunch. Back in 5 ; set away message to "Gone to lunch. - Back in 5". - - :WiZ AWAY ; unmark WiZ as being away. - - -5.2 Rehash message - - Command: REHASH - Parameters: None - - The rehash message can be used by the operator to force the server to - re-read and process its configuration file. - - Numeric Replies: - - RPL_REHASHING ERR_NOPRIVILEGES - -Examples: - -REHASH ; message from client with operator - status to server asking it to reread its - configuration file. - -5.3 Restart message - - Command: RESTART - Parameters: None - - The restart message can only be used by an operator to force a server - restart itself. This message is optional since it may be viewed as a - risk to allow arbitrary people to connect to a server as an operator - and execute this command, causing (at least) a disruption to service. - - - -Oikarinen & Reed [Page 39] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - The RESTART command must always be fully processed by the server to - which the sending client is connected and not be passed onto other - connected servers. - - Numeric Replies: - - ERR_NOPRIVILEGES - - Examples: - - RESTART ; no parameters required. - -5.4 Summon message - - Command: SUMMON - Parameters: <user> [<server>] - - The SUMMON command can be used to give users who are on a host - running an IRC server a message asking them to please join IRC. This - message is only sent if the target server (a) has SUMMON enabled, (b) - the user is logged in and (c) the server process can write to the - user's tty (or similar). - - If no <server> parameter is given it tries to summon <user> from the - server the client is connected to is assumed as the target. - - If summon is not enabled in a server, it must return the - ERR_SUMMONDISABLED numeric and pass the summon message onwards. - - Numeric Replies: - - ERR_NORECIPIENT ERR_FILEERROR - ERR_NOLOGIN ERR_NOSUCHSERVER - RPL_SUMMONING - - Examples: - - SUMMON jto ; summon user jto on the server's host - - SUMMON jto tolsun.oulu.fi ; summon user jto on the host which a - server named "tolsun.oulu.fi" is - running. - - -5.5 Users - - Command: USERS - Parameters: [<server>] - - - -Oikarinen & Reed [Page 40] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - The USERS command returns a list of users logged into the server in a - similar format to who(1), rusers(1) and finger(1). Some people - may disable this command on their server for security related - reasons. If disabled, the correct numeric must be returned to - indicate this. - - Numeric Replies: - - ERR_NOSUCHSERVER ERR_FILEERROR - RPL_USERSSTART RPL_USERS - RPL_NOUSERS RPL_ENDOFUSERS - ERR_USERSDISABLED - - Disabled Reply: - - ERR_USERSDISABLED - - Examples: - -USERS eff.org ; request a list of users logged in on - server eff.org - -:John USERS tolsun.oulu.fi ; request from John for a list of users - logged in on server tolsun.oulu.fi - -5.6 Operwall message - - Command: WALLOPS - Parameters: Text to be sent to all operators currently online - - Sends a message to all operators currently online. After - implementing WALLOPS as a user command it was found that it was - often and commonly abused as a means of sending a message to a lot - of people (much similar to WALL). Due to this it is recommended - that the current implementation of WALLOPS be used as an - example by allowing and recognising only servers as the senders of - WALLOPS. - - Numeric Replies: - - ERR_NEEDMOREPARAMS - - Examples: - - :csd.bu.edu WALLOPS :Connect '*.uiuc.edu 6667' from Joshua; WALLOPS - message from csd.bu.edu announcing a - CONNECT message it received and acted - upon from Joshua. - - - -Oikarinen & Reed [Page 41] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -5.7 Userhost message - - Command: USERHOST - Parameters: <nickname>{<space><nickname>} - - The USERHOST command takes a list of up to 5 nicknames, each - separated by a space character and returns a list of information - about each nickname that it found. The returned list has each reply - separated by a space. - - Numeric Replies: - - RPL_USERHOST ERR_NEEDMOREPARAMS - - Examples: - - USERHOST Wiz Michael Marty p ;USERHOST request for information on - nicks "Wiz", "Michael", "Marty" and "p" - -5.8 Ison message - - Command: ISON - Parameters: <nickname>{<space><nickname>} - - The ISON command was implemented to provide a quick and efficient - means to get a response about whether a given nickname was currently - on IRC. ISON only takes one (1) parameter: a space-separated list of - nicks. For each nickname in the list that is present, the server - adds that to its reply string. Thus the reply string may return - empty (none of the given nicks are present), an exact copy of the - parameter string (all of them present) or as any other subset of the - set of nicks given in the parameter. The only limit on the number - of nicks that may be checked is that the combined length must not be - too large as to cause the server to chop it off so it fits in 512 - characters. - - ISON is only be processed by the server local to the client sending - the command and thus not passed onto other servers for further - processing. - - Numeric Replies: - - RPL_ISON ERR_NEEDMOREPARAMS - - Examples: - - ISON phone trillian WiZ jarlek Avalon Angel Monstah - ; Sample ISON request for 7 nicks. - - - -Oikarinen & Reed [Page 42] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -6. REPLIES - - The following is a list of numeric replies which are generated in - response to the commands given above. Each numeric is given with its - number, name and reply string. - -6.1 Error Replies. - - 401 ERR_NOSUCHNICK - "<nickname> :No such nick/channel" - - - Used to indicate the nickname parameter supplied to a - command is currently unused. - - 402 ERR_NOSUCHSERVER - "<server name> :No such server" - - - Used to indicate the server name given currently - doesn't exist. - - 403 ERR_NOSUCHCHANNEL - "<channel name> :No such channel" - - - Used to indicate the given channel name is invalid. - - 404 ERR_CANNOTSENDTOCHAN - "<channel name> :Cannot send to channel" - - - Sent to a user who is either (a) not on a channel - which is mode +n or (b) not a chanop (or mode +v) on - a channel which has mode +m set and is trying to send - a PRIVMSG message to that channel. - - 405 ERR_TOOMANYCHANNELS - "<channel name> :You have joined too many \ - channels" - - Sent to a user when they have joined the maximum - number of allowed channels and they try to join - another channel. - - 406 ERR_WASNOSUCHNICK - "<nickname> :There was no such nickname" - - - Returned by WHOWAS to indicate there is no history - information for that nickname. - - 407 ERR_TOOMANYTARGETS - "<target> :Duplicate recipients. No message \ - - - -Oikarinen & Reed [Page 43] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - delivered" - - - Returned to a client which is attempting to send a - PRIVMSG/NOTICE using the user@host destination format - and for a user@host which has several occurrences. - - 409 ERR_NOORIGIN - ":No origin specified" - - - PING or PONG message missing the originator parameter - which is required since these commands must work - without valid prefixes. - - 411 ERR_NORECIPIENT - ":No recipient given (<command>)" - 412 ERR_NOTEXTTOSEND - ":No text to send" - 413 ERR_NOTOPLEVEL - "<mask> :No toplevel domain specified" - 414 ERR_WILDTOPLEVEL - "<mask> :Wildcard in toplevel domain" - - - 412 - 414 are returned by PRIVMSG to indicate that - the message wasn't delivered for some reason. - ERR_NOTOPLEVEL and ERR_WILDTOPLEVEL are errors that - are returned when an invalid use of - "PRIVMSG $<server>" or "PRIVMSG #<host>" is attempted. - - 421 ERR_UNKNOWNCOMMAND - "<command> :Unknown command" - - - Returned to a registered client to indicate that the - command sent is unknown by the server. - - 422 ERR_NOMOTD - ":MOTD File is missing" - - - Server's MOTD file could not be opened by the server. - - 423 ERR_NOADMININFO - "<server> :No administrative info available" - - - Returned by a server in response to an ADMIN message - when there is an error in finding the appropriate - information. - - 424 ERR_FILEERROR - ":File error doing <file op> on <file>" - - - -Oikarinen & Reed [Page 44] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - - Generic error message used to report a failed file - operation during the processing of a message. - - 431 ERR_NONICKNAMEGIVEN - ":No nickname given" - - - Returned when a nickname parameter expected for a - command and isn't found. - - 432 ERR_ERRONEUSNICKNAME - "<nick> :Erroneus nickname" - - - Returned after receiving a NICK message which contains - characters which do not fall in the defined set. See - section x.x.x for details on valid nicknames. - - 433 ERR_NICKNAMEINUSE - "<nick> :Nickname is already in use" - - - Returned when a NICK message is processed that results - in an attempt to change to a currently existing - nickname. - - 436 ERR_NICKCOLLISION - "<nick> :Nickname collision KILL" - - - Returned by a server to a client when it detects a - nickname collision (registered of a NICK that - already exists by another server). - - 441 ERR_USERNOTINCHANNEL - "<nick> <channel> :They aren't on that channel" - - - Returned by the server to indicate that the target - user of the command is not on the given channel. - - 442 ERR_NOTONCHANNEL - "<channel> :You're not on that channel" - - - Returned by the server whenever a client tries to - perform a channel effecting command for which the - client isn't a member. - - 443 ERR_USERONCHANNEL - "<user> <channel> :is already on channel" - - - Returned when a client tries to invite a user to a - channel they are already on. - - - -Oikarinen & Reed [Page 45] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 444 ERR_NOLOGIN - "<user> :User not logged in" - - - Returned by the summon after a SUMMON command for a - user was unable to be performed since they were not - logged in. - - 445 ERR_SUMMONDISABLED - ":SUMMON has been disabled" - - - Returned as a response to the SUMMON command. Must be - returned by any server which does not implement it. - - 446 ERR_USERSDISABLED - ":USERS has been disabled" - - - Returned as a response to the USERS command. Must be - returned by any server which does not implement it. - - 451 ERR_NOTREGISTERED - ":You have not registered" - - - Returned by the server to indicate that the client - must be registered before the server will allow it - to be parsed in detail. - - 461 ERR_NEEDMOREPARAMS - "<command> :Not enough parameters" - - - Returned by the server by numerous commands to - indicate to the client that it didn't supply enough - parameters. - - 462 ERR_ALREADYREGISTRED - ":You may not reregister" - - - Returned by the server to any link which tries to - change part of the registered details (such as - password or user details from second USER message). - - - 463 ERR_NOPERMFORHOST - ":Your host isn't among the privileged" - - - Returned to a client which attempts to register with - a server which does not been setup to allow - connections from the host the attempted connection - is tried. - - - -Oikarinen & Reed [Page 46] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 464 ERR_PASSWDMISMATCH - ":Password incorrect" - - - Returned to indicate a failed attempt at registering - a connection for which a password was required and - was either not given or incorrect. - - 465 ERR_YOUREBANNEDCREEP - ":You are banned from this server" - - - Returned after an attempt to connect and register - yourself with a server which has been setup to - explicitly deny connections to you. - - 467 ERR_KEYSET - "<channel> :Channel key already set" - 471 ERR_CHANNELISFULL - "<channel> :Cannot join channel (+l)" - 472 ERR_UNKNOWNMODE - "<char> :is unknown mode char to me" - 473 ERR_INVITEONLYCHAN - "<channel> :Cannot join channel (+i)" - 474 ERR_BANNEDFROMCHAN - "<channel> :Cannot join channel (+b)" - 475 ERR_BADCHANNELKEY - "<channel> :Cannot join channel (+k)" - 481 ERR_NOPRIVILEGES - ":Permission Denied- You're not an IRC operator" - - - Any command requiring operator privileges to operate - must return this error to indicate the attempt was - unsuccessful. - - 482 ERR_CHANOPRIVSNEEDED - "<channel> :You're not channel operator" - - - Any command requiring 'chanop' privileges (such as - MODE messages) must return this error if the client - making the attempt is not a chanop on the specified - channel. - - 483 ERR_CANTKILLSERVER - ":You cant kill a server!" - - - Any attempts to use the KILL command on a server - are to be refused and this error returned directly - to the client. - - - - -Oikarinen & Reed [Page 47] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 491 ERR_NOOPERHOST - ":No O-lines for your host" - - - If a client sends an OPER message and the server has - not been configured to allow connections from the - client's host as an operator, this error must be - returned. - - 501 ERR_UMODEUNKNOWNFLAG - ":Unknown MODE flag" - - - Returned by the server to indicate that a MODE - message was sent with a nickname parameter and that - the a mode flag sent was not recognized. - - 502 ERR_USERSDONTMATCH - ":Cant change mode for other users" - - - Error sent to any user trying to view or change the - user mode for a user other than themselves. - -6.2 Command responses. - - 300 RPL_NONE - Dummy reply number. Not used. - - 302 RPL_USERHOST - ":[<reply>{<space><reply>}]" - - - Reply format used by USERHOST to list replies to - the query list. The reply string is composed as - follows: - - <reply> ::= <nick>['*'] '=' <'+'|'-'><hostname> - - The '*' indicates whether the client has registered - as an Operator. The '-' or '+' characters represent - whether the client has set an AWAY message or not - respectively. - - 303 RPL_ISON - ":[<nick> {<space><nick>}]" - - - Reply format used by ISON to list replies to the - query list. - - 301 RPL_AWAY - "<nick> :<away message>" - - - -Oikarinen & Reed [Page 48] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - 305 RPL_UNAWAY - ":You are no longer marked as being away" - 306 RPL_NOWAWAY - ":You have been marked as being away" - - - These replies are used with the AWAY command (if - allowed). RPL_AWAY is sent to any client sending a - PRIVMSG to a client which is away. RPL_AWAY is only - sent by the server to which the client is connected. - Replies RPL_UNAWAY and RPL_NOWAWAY are sent when the - client removes and sets an AWAY message. - - 311 RPL_WHOISUSER - "<nick> <user> <host> * :<real name>" - 312 RPL_WHOISSERVER - "<nick> <server> :<server info>" - 313 RPL_WHOISOPERATOR - "<nick> :is an IRC operator" - 317 RPL_WHOISIDLE - "<nick> <integer> :seconds idle" - 318 RPL_ENDOFWHOIS - "<nick> :End of /WHOIS list" - 319 RPL_WHOISCHANNELS - "<nick> :{[@|+]<channel><space>}" - - - Replies 311 - 313, 317 - 319 are all replies - generated in response to a WHOIS message. Given that - there are enough parameters present, the answering - server must either formulate a reply out of the above - numerics (if the query nick is found) or return an - error reply. The '*' in RPL_WHOISUSER is there as - the literal character and not as a wild card. For - each reply set, only RPL_WHOISCHANNELS may appear - more than once (for long lists of channel names). - The '@' and '+' characters next to the channel name - indicate whether a client is a channel operator or - has been granted permission to speak on a moderated - channel. The RPL_ENDOFWHOIS reply is used to mark - the end of processing a WHOIS message. - - 314 RPL_WHOWASUSER - "<nick> <user> <host> * :<real name>" - 369 RPL_ENDOFWHOWAS - "<nick> :End of WHOWAS" - - - When replying to a WHOWAS message, a server must use - the replies RPL_WHOWASUSER, RPL_WHOISSERVER or - ERR_WASNOSUCHNICK for each nickname in the presented - - - -Oikarinen & Reed [Page 49] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - list. At the end of all reply batches, there must - be RPL_ENDOFWHOWAS (even if there was only one reply - and it was an error). - - 321 RPL_LISTSTART - "Channel :Users Name" - 322 RPL_LIST - "<channel> <# visible> :<topic>" - 323 RPL_LISTEND - ":End of /LIST" - - - Replies RPL_LISTSTART, RPL_LIST, RPL_LISTEND mark - the start, actual replies with data and end of the - server's response to a LIST command. If there are - no channels available to return, only the start - and end reply must be sent. - - 324 RPL_CHANNELMODEIS - "<channel> <mode> <mode params>" - - 331 RPL_NOTOPIC - "<channel> :No topic is set" - 332 RPL_TOPIC - "<channel> :<topic>" - - - When sending a TOPIC message to determine the - channel topic, one of two replies is sent. If - the topic is set, RPL_TOPIC is sent back else - RPL_NOTOPIC. - - 341 RPL_INVITING - "<channel> <nick>" - - - Returned by the server to indicate that the - attempted INVITE message was successful and is - being passed onto the end client. - - 342 RPL_SUMMONING - "<user> :Summoning user to IRC" - - - Returned by a server answering a SUMMON message to - indicate that it is summoning that user. - - 351 RPL_VERSION - "<version>.<debuglevel> <server> :<comments>" - - - Reply by the server showing its version details. - The <version> is the version of the software being - - - -Oikarinen & Reed [Page 50] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - used (including any patchlevel revisions) and the - <debuglevel> is used to indicate if the server is - running in "debug mode". - - The "comments" field may contain any comments about - the version or further version details. - - 352 RPL_WHOREPLY - "<channel> <user> <host> <server> <nick> \ - <H|G>[*][@|+] :<hopcount> <real name>" - 315 RPL_ENDOFWHO - "<name> :End of /WHO list" - - - The RPL_WHOREPLY and RPL_ENDOFWHO pair are used - to answer a WHO message. The RPL_WHOREPLY is only - sent if there is an appropriate match to the WHO - query. If there is a list of parameters supplied - with a WHO message, a RPL_ENDOFWHO must be sent - after processing each list item with <name> being - the item. - - 353 RPL_NAMREPLY - "<channel> :[[@|+]<nick> [[@|+]<nick> [...]]]" - 366 RPL_ENDOFNAMES - "<channel> :End of /NAMES list" - - - To reply to a NAMES message, a reply pair consisting - of RPL_NAMREPLY and RPL_ENDOFNAMES is sent by the - server back to the client. If there is no channel - found as in the query, then only RPL_ENDOFNAMES is - returned. The exception to this is when a NAMES - message is sent with no parameters and all visible - channels and contents are sent back in a series of - RPL_NAMEREPLY messages with a RPL_ENDOFNAMES to mark - the end. - - 364 RPL_LINKS - "<mask> <server> :<hopcount> <server info>" - 365 RPL_ENDOFLINKS - "<mask> :End of /LINKS list" - - - In replying to the LINKS message, a server must send - replies back using the RPL_LINKS numeric and mark the - end of the list using an RPL_ENDOFLINKS reply. - - 367 RPL_BANLIST - "<channel> <banid>" - 368 RPL_ENDOFBANLIST - - - -Oikarinen & Reed [Page 51] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - "<channel> :End of channel ban list" - - - When listing the active 'bans' for a given channel, - a server is required to send the list back using the - RPL_BANLIST and RPL_ENDOFBANLIST messages. A separate - RPL_BANLIST is sent for each active banid. After the - banids have been listed (or if none present) a - RPL_ENDOFBANLIST must be sent. - - 371 RPL_INFO - ":<string>" - 374 RPL_ENDOFINFO - ":End of /INFO list" - - - A server responding to an INFO message is required to - send all its 'info' in a series of RPL_INFO messages - with a RPL_ENDOFINFO reply to indicate the end of the - replies. - - 375 RPL_MOTDSTART - ":- <server> Message of the day - " - 372 RPL_MOTD - ":- <text>" - 376 RPL_ENDOFMOTD - ":End of /MOTD command" - - - When responding to the MOTD message and the MOTD file - is found, the file is displayed line by line, with - each line no longer than 80 characters, using - RPL_MOTD format replies. These should be surrounded - by a RPL_MOTDSTART (before the RPL_MOTDs) and an - RPL_ENDOFMOTD (after). - - 381 RPL_YOUREOPER - ":You are now an IRC operator" - - - RPL_YOUREOPER is sent back to a client which has - just successfully issued an OPER message and gained - operator status. - - 382 RPL_REHASHING - "<config file> :Rehashing" - - - If the REHASH option is used and an operator sends - a REHASH message, an RPL_REHASHING is sent back to - the operator. - - 391 RPL_TIME - - - -Oikarinen & Reed [Page 52] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - "<server> :<string showing server's local time>" - - - When replying to the TIME message, a server must send - the reply using the RPL_TIME format above. The string - showing the time need only contain the correct day and - time there. There is no further requirement for the - time string. - - 392 RPL_USERSSTART - ":UserID Terminal Host" - 393 RPL_USERS - ":%-8s %-9s %-8s" - 394 RPL_ENDOFUSERS - ":End of users" - 395 RPL_NOUSERS - ":Nobody logged in" - - - If the USERS message is handled by a server, the - replies RPL_USERSTART, RPL_USERS, RPL_ENDOFUSERS and - RPL_NOUSERS are used. RPL_USERSSTART must be sent - first, following by either a sequence of RPL_USERS - or a single RPL_NOUSER. Following this is - RPL_ENDOFUSERS. - - 200 RPL_TRACELINK - "Link <version & debug level> <destination> \ - <next server>" - 201 RPL_TRACECONNECTING - "Try. <class> <server>" - 202 RPL_TRACEHANDSHAKE - "H.S. <class> <server>" - 203 RPL_TRACEUNKNOWN - "???? <class> [<client IP address in dot form>]" - 204 RPL_TRACEOPERATOR - "Oper <class> <nick>" - 205 RPL_TRACEUSER - "User <class> <nick>" - 206 RPL_TRACESERVER - "Serv <class> <int>S <int>C <server> \ - <nick!user|*!*>@<host|server>" - 208 RPL_TRACENEWTYPE - "<newtype> 0 <client name>" - 261 RPL_TRACELOG - "File <logfile> <debug level>" - - - The RPL_TRACE* are all returned by the server in - response to the TRACE message. How many are - returned is dependent on the the TRACE message and - - - -Oikarinen & Reed [Page 53] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - whether it was sent by an operator or not. There - is no predefined order for which occurs first. - Replies RPL_TRACEUNKNOWN, RPL_TRACECONNECTING and - RPL_TRACEHANDSHAKE are all used for connections - which have not been fully established and are either - unknown, still attempting to connect or in the - process of completing the 'server handshake'. - RPL_TRACELINK is sent by any server which handles - a TRACE message and has to pass it on to another - server. The list of RPL_TRACELINKs sent in - response to a TRACE command traversing the IRC - network should reflect the actual connectivity of - the servers themselves along that path. - RPL_TRACENEWTYPE is to be used for any connection - which does not fit in the other categories but is - being displayed anyway. - - 211 RPL_STATSLINKINFO - "<linkname> <sendq> <sent messages> \ - <sent bytes> <received messages> \ - <received bytes> <time open>" - 212 RPL_STATSCOMMANDS - "<command> <count>" - 213 RPL_STATSCLINE - "C <host> * <name> <port> <class>" - 214 RPL_STATSNLINE - "N <host> * <name> <port> <class>" - 215 RPL_STATSILINE - "I <host> * <host> <port> <class>" - 216 RPL_STATSKLINE - "K <host> * <username> <port> <class>" - 218 RPL_STATSYLINE - "Y <class> <ping frequency> <connect \ - frequency> <max sendq>" - 219 RPL_ENDOFSTATS - "<stats letter> :End of /STATS report" - 241 RPL_STATSLLINE - "L <hostmask> * <servername> <maxdepth>" - 242 RPL_STATSUPTIME - ":Server Up %d days %d:%02d:%02d" - 243 RPL_STATSOLINE - "O <hostmask> * <name>" - 244 RPL_STATSHLINE - "H <hostmask> * <servername>" - - 221 RPL_UMODEIS - "<user mode string>" - - - - -Oikarinen & Reed [Page 54] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - - To answer a query about a client's own mode, - RPL_UMODEIS is sent back. - - 251 RPL_LUSERCLIENT - ":There are <integer> users and <integer> \ - invisible on <integer> servers" - 252 RPL_LUSEROP - "<integer> :operator(s) online" - 253 RPL_LUSERUNKNOWN - "<integer> :unknown connection(s)" - 254 RPL_LUSERCHANNELS - "<integer> :channels formed" - 255 RPL_LUSERME - ":I have <integer> clients and <integer> \ - servers" - - - In processing an LUSERS message, the server - sends a set of replies from RPL_LUSERCLIENT, - RPL_LUSEROP, RPL_USERUNKNOWN, - RPL_LUSERCHANNELS and RPL_LUSERME. When - replying, a server must send back - RPL_LUSERCLIENT and RPL_LUSERME. The other - replies are only sent back if a non-zero count - is found for them. - - 256 RPL_ADMINME - "<server> :Administrative info" - 257 RPL_ADMINLOC1 - ":<admin info>" - 258 RPL_ADMINLOC2 - ":<admin info>" - 259 RPL_ADMINEMAIL - ":<admin info>" - - - When replying to an ADMIN message, a server - is expected to use replies RLP_ADMINME - through to RPL_ADMINEMAIL and provide a text - message with each. For RPL_ADMINLOC1 a - description of what city, state and country - the server is in is expected, followed by - details of the university and department - (RPL_ADMINLOC2) and finally the administrative - contact for the server (an email address here - is required) in RPL_ADMINEMAIL. - - - - - - - -Oikarinen & Reed [Page 55] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -6.3 Reserved numerics. - - These numerics are not described above since they fall into one of - the following categories: - - 1. no longer in use; - - 2. reserved for future planned use; - - 3. in current use but are part of a non-generic 'feature' of - the current IRC server. - - 209 RPL_TRACECLASS 217 RPL_STATSQLINE - 231 RPL_SERVICEINFO 232 RPL_ENDOFSERVICES - 233 RPL_SERVICE 234 RPL_SERVLIST - 235 RPL_SERVLISTEND - 316 RPL_WHOISCHANOP 361 RPL_KILLDONE - 362 RPL_CLOSING 363 RPL_CLOSEEND - 373 RPL_INFOSTART 384 RPL_MYPORTIS - 466 ERR_YOUWILLBEBANNED 476 ERR_BADCHANMASK - 492 ERR_NOSERVICEHOST - -7. Client and server authentication - - Clients and servers are both subject to the same level of - authentication. For both, an IP number to hostname lookup (and - reverse check on this) is performed for all connections made to the - server. Both connections are then subject to a password check (if - there is a password set for that connection). These checks are - possible on all connections although the password check is only - commonly used with servers. - - An additional check that is becoming of more and more common is that - of the username responsible for making the connection. Finding the - username of the other end of the connection typically involves - connecting to an authentication server such as IDENT as described in - RFC 1413. - - Given that without passwords it is not easy to reliably determine who - is on the other end of a network connection, use of passwords is - strongly recommended on inter-server connections in addition to any - other measures such as using an ident server. - -8. Current implementations - - The only current implementation of this protocol is the IRC server, - version 2.8. Earlier versions may implement some or all of the - commands described by this document with NOTICE messages replacing - - - -Oikarinen & Reed [Page 56] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - many of the numeric replies. Unfortunately, due to backward - compatibility requirements, the implementation of some parts of this - document varies with what is laid out. On notable difference is: - - * recognition that any LF or CR anywhere in a message marks the - end of that message (instead of requiring CR-LF); - - The rest of this section deals with issues that are mostly of - importance to those who wish to implement a server but some parts - also apply directly to clients as well. - -8.1 Network protocol: TCP - why it is best used here. - - IRC has been implemented on top of TCP since TCP supplies a reliable - network protocol which is well suited to this scale of conferencing. - The use of multicast IP is an alternative, but it is not widely - available or supported at the present time. - -8.1.1 Support of Unix sockets - - Given that Unix domain sockets allow listen/connect operations, the - current implementation can be configured to listen and accept both - client and server connections on a Unix domain socket. These are - recognized as sockets where the hostname starts with a '/'. - - When providing any information about the connections on a Unix domain - socket, the server is required to supplant the actual hostname in - place of the pathname unless the actual socket name is being asked - for. - -8.2 Command Parsing - - To provide useful 'non-buffered' network IO for clients and servers, - each connection is given its own private 'input buffer' in which the - results of the most recent read and parsing are kept. A buffer size - of 512 bytes is used so as to hold 1 full message, although, this - will usually hold several commands. The private buffer is parsed - after every read operation for valid messages. When dealing with - multiple messages from one client in the buffer, care should be taken - in case one happens to cause the client to be 'removed'. - -8.3 Message delivery - - It is common to find network links saturated or hosts to which you - are sending data unable to send data. Although Unix typically - handles this through the TCP window and internal buffers, the server - often has large amounts of data to send (especially when a new - server-server link forms) and the small buffers provided in the - - - -Oikarinen & Reed [Page 57] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - kernel are not enough for the outgoing queue. To alleviate this - problem, a "send queue" is used as a FIFO queue for data to be sent. - A typical "send queue" may grow to 200 Kbytes on a large IRC network - with a slow network connection when a new server connects. - - When polling its connections, a server will first read and parse all - incoming data, queuing any data to be sent out. When all available - input is processed, the queued data is sent. This reduces the number - of write() system calls and helps TCP make bigger packets. - -8.4 Connection 'Liveness' - - To detect when a connection has died or become unresponsive, the - server must ping each of its connections that it doesn't get a - response from in a given amount of time. - - If a connection doesn't respond in time, its connection is closed - using the appropriate procedures. A connection is also dropped if - its sendq grows beyond the maximum allowed, because it is better to - close a slow connection than have a server process block. - -8.5 Establishing a server to client connection - - Upon connecting to an IRC server, a client is sent the MOTD (if - present) as well as the current user/server count (as per the LUSER - command). The server is also required to give an unambiguous message - to the client which states its name and version as well as any other - introductory messages which may be deemed appropriate. - - After dealing with this, the server must then send out the new user's - nickname and other information as supplied by itself (USER command) - and as the server could discover (from DNS/authentication servers). - The server must send this information out with NICK first followed by - USER. - -8.6 Establishing a server-server connection. - - The process of establishing of a server-to-server connection is - fraught with danger since there are many possible areas where - problems can occur - the least of which are race conditions. - - After a server has received a connection following by a PASS/SERVER - pair which were recognised as being valid, the server should then - reply with its own PASS/SERVER information for that connection as - well as all of the other state information it knows about as - described below. - - When the initiating server receives a PASS/SERVER pair, it too then - - - -Oikarinen & Reed [Page 58] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - checks that the server responding is authenticated properly before - accepting the connection to be that server. - -8.6.1 Server exchange of state information when connecting - - The order of state information being exchanged between servers is - essential. The required order is as follows: - - * all known other servers; - - * all known user information; - - * all known channel information. - - Information regarding servers is sent via extra SERVER messages, user - information with NICK/USER/MODE/JOIN messages and channels with MODE - messages. - - NOTE: channel topics are *NOT* exchanged here because the TOPIC - command overwrites any old topic information, so at best, the two - sides of the connection would exchange topics. - - By passing the state information about servers first, any collisions - with servers that already exist occur before nickname collisions due - to a second server introducing a particular nickname. Due to the IRC - network only being able to exist as an acyclic graph, it may be - possible that the network has already reconnected in another - location, the place where the collision occurs indicating where the - net needs to split. - -8.7 Terminating server-client connections - - When a client connection closes, a QUIT message is generated on - behalf of the client by the server to which the client connected. No - other message is to be generated or used. - -8.8 Terminating server-server connections - - If a server-server connection is closed, either via a remotely - generated SQUIT or 'natural' causes, the rest of the connected IRC - network must have its information updated with by the server which - detected the closure. The server then sends a list of SQUITs (one - for each server behind that connection) and a list of QUITs (again, - one for each client behind that connection). - - - - - - - -Oikarinen & Reed [Page 59] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -8.9 Tracking nickname changes - - All IRC servers are required to keep a history of recent nickname - changes. This is required to allow the server to have a chance of - keeping in touch of things when nick-change race conditions occur - with commands which manipulate them. Commands which must trace nick - changes are: - - * KILL (the nick being killed) - - * MODE (+/- o,v) - - * KICK (the nick being kicked) - - No other commands are to have nick changes checked for. - - In the above cases, the server is required to first check for the - existence of the nickname, then check its history to see who that - nick currently belongs to (if anyone!). This reduces the chances of - race conditions but they can still occur with the server ending up - affecting the wrong client. When performing a change trace for an - above command it is recommended that a time range be given and - entries which are too old ignored. - - For a reasonable history, a server should be able to keep previous - nickname for every client it knows about if they all decided to - change. This size is limited by other factors (such as memory, etc). - -8.10 Flood control of clients - - With a large network of interconnected IRC servers, it is quite easy - for any single client attached to the network to supply a continuous - stream of messages that result in not only flooding the network, but - also degrading the level of service provided to others. Rather than - require every 'victim' to be provide their own protection, flood - protection was written into the server and is applied to all clients - except services. The current algorithm is as follows: - - * check to see if client's `message timer' is less than - current time (set to be equal if it is); - - * read any data present from the client; - - * while the timer is less than ten seconds ahead of the current - time, parse any present messages and penalize the client by - 2 seconds for each message; - - which in essence means that the client may send 1 message every 2 - - - -Oikarinen & Reed [Page 60] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - seconds without being adversely affected. - -8.11 Non-blocking lookups - - In a real-time environment, it is essential that a server process do - as little waiting as possible so that all the clients are serviced - fairly. Obviously this requires non-blocking IO on all network - read/write operations. For normal server connections, this was not - difficult, but there are other support operations that may cause the - server to block (such as disk reads). Where possible, such activity - should be performed with a short timeout. - -8.11.1 Hostname (DNS) lookups - - Using the standard resolver libraries from Berkeley and others has - meant large delays in some cases where replies have timed out. To - avoid this, a separate set of DNS routines were written which were - setup for non-blocking IO operations and then polled from within the - main server IO loop. - -8.11.2 Username (Ident) lookups - - Although there are numerous ident libraries for use and inclusion - into other programs, these caused problems since they operated in a - synchronous manner and resulted in frequent delays. Again the - solution was to write a set of routines which would cooperate with - the rest of the server and work using non-blocking IO. - -8.12 Configuration File - - To provide a flexible way of setting up and running the server, it is - recommended that a configuration file be used which contains - instructions to the server on the following: - - * which hosts to accept client connections from; - - * which hosts to allow to connect as servers; - - * which hosts to connect to (both actively and - passively); - - * information about where the server is (university, - city/state, company are examples of this); - - * who is responsible for the server and an email address - at which they can be contacted; - - * hostnames and passwords for clients which wish to be given - - - -Oikarinen & Reed [Page 61] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - access to restricted operator commands. - - In specifying hostnames, both domain names and use of the 'dot' - notation (127.0.0.1) should both be accepted. It must be possible to - specify the password to be used/accepted for all outgoing and - incoming connections (although the only outgoing connections are - those to other servers). - - The above list is the minimum requirement for any server which wishes - to make a connection with another server. Other items which may be - of use are: - - * specifying which servers other server may introduce; - - * how deep a server branch is allowed to become; - - * hours during which clients may connect. - -8.12.1 Allowing clients to connect - - A server should use some sort of 'access control list' (either in the - configuration file or elsewhere) that is read at startup and used to - decide what hosts clients may use to connect to it. - - Both 'deny' and 'allow' should be implemented to provide the required - flexibility for host access control. - -8.12.2 Operators - - The granting of operator privileges to a disruptive person can have - dire consequences for the well-being of the IRC net in general due to - the powers given to them. Thus, the acquisition of such powers - should not be very easy. The current setup requires two 'passwords' - to be used although one of them is usually easy guessed. Storage of - oper passwords in configuration files is preferable to hard coding - them in and should be stored in a crypted format (ie using crypt(3) - from Unix) to prevent easy theft. - -8.12.3 Allowing servers to connect - - The interconnection of server is not a trivial matter: a bad - connection can have a large impact on the usefulness of IRC. Thus, - each server should have a list of servers to which it may connect and - which servers may connect to it. Under no circumstances should a - server allow an arbitrary host to connect as a server. In addition - to which servers may and may not connect, the configuration file - should also store the password and other characteristics of that - link. - - - -Oikarinen & Reed [Page 62] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -8.12.4 Administrivia - - To provide accurate and valid replies to the ADMIN command (see - section 4.3.7), the server should find the relevant details in the - configuration. - -8.13 Channel membership - - The current server allows any registered local user to join upto 10 - different channels. There is no limit imposed on non-local users so - that the server remains (reasonably) consistant with all others on a - channel membership basis - -9. Current problems - - There are a number of recognized problems with this protocol, all of - which hope to be solved sometime in the near future during its - rewrite. Currently, work is underway to find working solutions to - these problems. - -9.1 Scalability - - It is widely recognized that this protocol does not scale - sufficiently well when used in a large arena. The main problem comes - from the requirement that all servers know about all other servers - and users and that information regarding them be updated as soon as - it changes. It is also desirable to keep the number of servers low - so that the path length between any two points is kept minimal and - the spanning tree as strongly branched as possible. - -9.2 Labels - - The current IRC protocol has 3 types of labels: the nickname, the - channel name and the server name. Each of the three types has its - own domain and no duplicates are allowed inside that domain. - Currently, it is possible for users to pick the label for any of the - three, resulting in collisions. It is widely recognized that this - needs reworking, with a plan for unique names for channels and nicks - that don't collide being desirable as well as a solution allowing a - cyclic tree. - -9.2.1 Nicknames - - The idea of the nickname on IRC is very convenient for users to use - when talking to each other outside of a channel, but there is only a - finite nickname space and being what they are, its not uncommon for - several people to want to use the same nick. If a nickname is chosen - by two people using this protocol, either one will not succeed or - - - -Oikarinen & Reed [Page 63] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - - both will removed by use of KILL (4.6.1). - -9.2.2 Channels - - The current channel layout requires that all servers know about all - channels, their inhabitants and properties. Besides not scaling - well, the issue of privacy is also a concern. A collision of - channels is treated as an inclusive event (both people who create the - new channel are considered to be members of it) rather than an - exclusive one such as used to solve nickname collisions. - -9.2.3 Servers - - Although the number of servers is usually small relative to the - number of users and channels, they two currently required to be known - globally, either each one separately or hidden behind a mask. - -9.3 Algorithms - - In some places within the server code, it has not been possible to - avoid N^2 algorithms such as checking the channel list of a set - of clients. - - In current server versions, there are no database consistency checks, - each server assumes that a neighbouring server is correct. This - opens the door to large problems if a connecting server is buggy or - otherwise tries to introduce contradictions to the existing net. - - Currently, because of the lack of unique internal and global labels, - there are a multitude of race conditions that exist. These race - conditions generally arise from the problem of it taking time for - messages to traverse and effect the IRC network. Even by changing to - unique labels, there are problems with channel-related commands being - disrupted. - -10. Current support and availability - - Mailing lists for IRC related discussion: - Future protocol: ircd-three-request@eff.org - General discussion: operlist-request@eff.org - - Software implemenations - cs.bu.edu:/irc - nic.funet.fi:/pub/irc - coombs.anu.edu.au:/pub/irc - - Newsgroup: alt.irc - - - - -Oikarinen & Reed [Page 64] - -RFC 1459 Internet Relay Chat Protocol May 1993 - - -Security Considerations - - Security issues are discussed in sections 4.1, 4.1.1, 4.1.3, 5.5, and - 7. - -12. Authors' Addresses - - Jarkko Oikarinen - Tuirantie 17 as 9 - 90500 OULU - FINLAND - - Email: jto@tolsun.oulu.fi - - - Darren Reed - 4 Pateman Street - Watsonia, Victoria 3087 - Australia - - Email: avalon@coombs.anu.edu.au - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Oikarinen & Reed [Page 65] -
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