/* dns.h - dns library declarations 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" struct dns_ip4list { in_addr ip; dns_ip4list *next; }; /** * 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 }; /** The DNS class allows fast nonblocking resolution of hostnames * and ip addresses. It is based heavily upon firedns by Ian Gulliver. * Modules SHOULD avoid using this class to resolve hostnames and IP * addresses, as it is a low-level wrapper around the UDP socket routines * and is probably not abstracted enough for real use. Please see the * Resolver class if you wish to resolve hostnames. */ class DNS : public Extensible { private: in_addr *binip; char* result; char localbuf[1024]; int t; void dns_init(); int myfd; void dns_init_2(const char* dnsserver); in_addr *dns_aton4(const char * const ipstring); char *dns_ntoa4(const in_addr * const ip); int dns_getip4(const char * const name); int dns_getip4list(const char * const name); int dns_getname4(const in_addr * const ip); char *dns_getresult(const int fd); in_addr *dns_aton4_s(const char * const ipstring, in_addr * const ip); char *dns_ntoa4_s(const in_addr * const ip, char * const result); char *dns_getresult_s(const int fd, char * const result); in_addr *dns_aton4_r(const char * const ipstring); char *dns_ntoa4_r(const in_addr * const ip); char *dns_getresult_r(const int fd); public: /** The default constructor uses dns addresses read from /etc/resolv.conf. * Please note that it will re-read /etc/resolv.conf for each copy of the * class you instantiate, causing disk access and slow lookups if you create * a lot of them. Consider passing the constructor a server address as a parameter * instead. */ DNS(); /** This constructor accepts a dns server address. The address must be in dotted * decimal form, e.g. 1.2.3.4. */ DNS(const std::string &dnsserver); /** The destructor frees all used structures. */ ~DNS(); /** This method will start the reverse lookup of an ip given in dotted decimal * format, e.g. 1.2.3.4, and returns true if the lookup was successfully * initiated. */ bool ReverseLookup(const std::string &ip, bool ins); /** This method will start the forward lookup of a hostname, e.g. www.inspircd.org, * and returns true if the lookup was successfully initiated. */ bool ForwardLookup(const std::string &host, bool ins); /** Used by modules to perform a dns lookup but have the socket engine poll a module, instead of the dns object directly. */ bool ForwardLookupWithFD(const std::string &host, int &fd); /** This method will return true when the lookup is completed. It uses poll internally * to determine the status of the socket. */ bool HasResult(); /** This method will return true if the lookup's fd matches the one provided */ bool HasResult(int fd); /** This method returns the result of your query as a string, depending upon wether you * called DNS::ReverseLookup() or DNS::ForwardLookup. */ std::string GetResult(); std::string GetResultIP(); /** This method returns the file handle used by the dns query socket or zero if the * query is invalid for some reason, e.g. the dns server not responding. */ int GetFD(); void SetNS(const std::string &dnsserver); }; /** * The Resolver class is a high-level abstraction for resolving DNS entries. * It can do forward and reverse IPv4 lookups, and when 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 { private: /** * The lowlevel DNS object used by Resolver */ DNS Query; /** * The input data, either a host or an IP address */ std::string input; /** * True if a forward lookup is being performed, false if otherwise */ bool fwd; /** * 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 file descriptor used for the DNS lookup */ int fd; /** * The output data, e.g. a hostname or an IP. */ std::string result; 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. * @param dnsserver This optional parameter specifies an alterate nameserver to use. * If it is not specified, or is an empty string, the value of ServerConfig::DNSServer * is used instead. * @throw ModuleException This class may throw an instance of ModuleException, in the * event there are no more file descriptors, or a similar hard error occurs such as * the network being down. */ Resolver(const std::string &source, bool forward, const std::string &dnsserver); /** * 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); /** * 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. */ virtual void OnError(ResolverError e); /** * This method is called by the core when the object's file descriptor is ready * for reading, and will then dispatch a call to either OnLookupComplete or * OnError. You should never call this method yourself. */ bool ProcessResult(); /** * Returns the file descriptor 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. */ int GetFd(); }; /** * Clear the pointer table used for Resolver classes */ void init_dns(); /** * Deal with a Resolver class which has become writeable */ void dns_deal_with_classes(int fd); /** * Add a resolver class to our active table */ bool dns_add_class(Resolver* r); #ifdef THREADED_DNS /** This is the handler function for multi-threaded DNS. * It cannot be a class member as pthread will not let us * create a thread whos handler function is a member of * a class (ugh). */ void* dns_task(void* arg); #endif #endif