/* +------------------------------------+ * | Inspire Internet Relay Chat Daemon | * +------------------------------------+ * * InspIRCd is copyright (C) 2002-2006 ChatSpike-Dev. * E-mail: * * * * Written by Craig Edwards, Craig McLure, and others. * This program is free but copyrighted software; see * the file COPYING for details. * * --------------------------------------------------- */ /* dns.h - dns library very very loosely based on firedns, Copyright (C) 2002 Ian Gulliver This program is free software; you can redistribute it and/or modify it under the terms of version 2 of the GNU General Public License as published by the Free Software Foundation. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #ifndef _DNS_H #define _DNS_H #include #include "inspircd_config.h" #include "socket.h" #include "base.h" /** * Result status, used internally */ typedef std::pair DNSResult; /** * Information on a completed lookup, used internally */ typedef std::pair DNSInfo; /** * Error types that class Resolver can emit to its error method. */ enum ResolverError { RESOLVER_NOERROR = 0, RESOLVER_NSDOWN = 1, RESOLVER_NXDOMAIN = 2, RESOLVER_NOTREADY = 3, RESOLVER_BADIP = 4 }; /** * A DNS request */ class DNSRequest; /** * A DNS packet header */ class DNSHeader; /** * A DNS Resource Record (rr) */ class ResourceRecord; /** * A set of requests keyed by request id */ typedef std::map requestlist; /** * An iterator into a set of requests */ typedef requestlist::iterator requestlist_iter; /** * Query and resource record types */ enum QueryType { DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */ DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */ DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */ DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */ }; #ifdef IPV6 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA; const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR; #else const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A; const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR; #endif /** * The Resolver class is a high-level abstraction for resolving DNS entries. * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will * also be able to do those, transparent of protocols. Module developers must * extend this class via inheritence, and then insert a pointer to their derived * class into the core using Server::AddResolver(). Once you have done this, * the class will be able to receive callbacks. There are two callbacks which * can occur by calling virtual methods, one is a success situation, and the other * an error situation. */ class Resolver : public Extensible { protected: /** * The input data, either a host or an IP address */ std::string input; /** * True if a forward lookup is being performed, false if otherwise */ QueryType querytype; /** * The DNS erver being used for lookups. If this is an empty string, * the value of ServerConfig::DNSServer is used instead. */ std::string server; /** * The ID allocated to your lookup. This is a pseudo-random number * between 0 and 65535, a value of -1 indicating a failure. * The core uses this to route results to the correct objects. */ int myid; public: /** * Initiate DNS lookup. Your class should not attempt to delete or free these * objects, as the core will do this for you. They must always be created upon * the heap using new, as you cannot be sure at what time they will be deleted. * Allocating them on the stack or attempting to delete them yourself could cause * the object to go 'out of scope' and cause a segfault in the core if the result * arrives at a later time. * @param source The IP or hostname to resolve * @param forward Set to true to perform a forward lookup (hostname to ip) or false * to perform a reverse lookup (ip to hostname). Lookups on A records and PTR * records are supported. CNAME and MX are not supported by this resolver. * If InspIRCd is compiled with ipv6 support, lookups on AAAA records are preferred * and supported over A records. * @throw ModuleException This class may throw an instance of ModuleException, in the * event a lookup could not be allocated, or a similar hard error occurs such as * the network being down. */ Resolver(const std::string &source, QueryType qt); /** * The default destructor does nothing. */ virtual ~Resolver(); /** * When your lookup completes, this method will be called. * @param result The resulting DNS lookup, either an IP address or a hostname. */ virtual void OnLookupComplete(const std::string &result) = 0; /** * If an error occurs (such as NXDOMAIN, no domain name found) then this method * will be called. * @param e A ResolverError enum containing the error type which has occured. * @param errormessage The error text of the error that occured. */ virtual void OnError(ResolverError e, const std::string &errormessage); /** * Returns the id value of this class. This is primarily used by the core * to determine where in various tables to place a pointer to your class, but it * is safe to call and use this method. * As specified in RFC1035, each dns request has a 16 bit ID value, ranging * from 0 to 65535. If there is an issue and the core cannot send your request, * this method will return -1. */ int GetId(); }; /** DNS is a singleton class used by the core to dispatch dns * requests to the dns server, and route incoming dns replies * back to Resolver objects, based upon the request ID. You * should never use this class yourself. */ class DNS : public Extensible { private: /** * The maximum value of a dns request id, * 16 bits wide, 0xFFFF. */ static const int MAX_REQUEST_ID = 0xFFFF; /** * Requests that are currently 'in flight' */ requestlist requests; /** * Server address being used currently */ insp_inaddr myserver; /** * File descriptor being used to perform queries */ static int MasterSocket; /** * A counter used to form part of the pseudo-random id */ int currid; /** * Currently active Resolver classes */ Resolver* Classes[MAX_REQUEST_ID]; /** * Build a dns packet payload */ int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload); public: /** * The port number DNS requests are made on, * and replies have as a source-port number. */ static const int QUERY_PORT = 53; /** * Fill an rr (resource record) with data from input */ static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input); /** * Fill a header with data from input limited by a length */ static void FillHeader(DNSHeader *header, const unsigned char *input, const int length); /** * Empty out a header into a data stream ready for transmission "on the wire" */ static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length); /** * Get the master socket fd, used internally */ static int GetMasterSocket(); /** * Start the lookup of an ipv4 from a hostname */ int GetIP(const char* name); /** * Start the lookup of a hostname from an ip */ int GetName(const insp_inaddr* ip); /** * Start lookup of an ipv6 from a hostname */ int GetIP6(const char *name); /** * Start lookup of a CNAME from another hostname */ int GetCName(const char* alias); /** * Fetch the result string (an ip or host) * and/or an error message to go with it. */ DNSResult GetResult(); /** * Handle a SocketEngine read event */ void MarshallReads(int fd); /** * Add a Resolver* to the list of active classes */ bool AddResolverClass(Resolver* r); /** * Add a query to the list to be sent */ DNSRequest* AddQuery(DNSHeader *header, int &id); /** * The constructor initialises the dns socket, * and clears the request lists. */ DNS(); /** * Destructor */ ~DNS(); /** Portable random number generator, generates * its random number from the ircd stats counters, * effective user id, time of day and the rollover * counter (currid) */ unsigned long PRNG(); }; #endif