1 /* +------------------------------------+
2 * | Inspire Internet Relay Chat Daemon |
3 * +------------------------------------+
5 * InspIRCd is copyright (C) 2002-2006 ChatSpike-Dev.
7 * <brain@chatspike.net>
8 * <Craig@chatspike.net>
10 * Written by Craig Edwards, Craig McLure, and others.
11 * This program is free but copyrighted software; see
12 * the file COPYING for details.
14 * ---------------------------------------------------
18 dns.h - dns library very very loosely based on
19 firedns, Copyright (C) 2002 Ian Gulliver
21 This program is free software; you can redistribute it and/or modify
22 it under the terms of version 2 of the GNU General Public License as
23 published by the Free Software Foundation.
25 This program is distributed in the hope that it will be useful,
26 but WITHOUT ANY WARRANTY; without even the implied warranty of
27 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
28 GNU General Public License for more details.
30 You should have received a copy of the GNU General Public License
31 along with this program; if not, write to the Free Software
32 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
39 #include "inspircd_config.h"
44 * Result status, used internally
46 typedef std::pair<int,std::string> DNSResult;
49 * Information on a completed lookup, used internally
51 typedef std::pair<unsigned char*, std::string> DNSInfo;
54 * Error types that class Resolver can emit to its error method.
60 RESOLVER_NXDOMAIN = 2,
61 RESOLVER_NOTREADY = 3,
76 * A DNS Resource Record (rr)
81 * A set of requests keyed by request id
83 typedef std::map<int,DNSRequest*> requestlist;
86 * An iterator into a set of requests
88 typedef requestlist::iterator requestlist_iter;
91 * Query and resource record types
95 DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
96 DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
97 DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
98 DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
102 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
103 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
105 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
106 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
110 * The Resolver class is a high-level abstraction for resolving DNS entries.
111 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
112 * also be able to do those, transparent of protocols. Module developers must
113 * extend this class via inheritence, and then insert a pointer to their derived
114 * class into the core using Server::AddResolver(). Once you have done this,
115 * the class will be able to receive callbacks. There are two callbacks which
116 * can occur by calling virtual methods, one is a success situation, and the other
117 * an error situation.
119 class Resolver : public Extensible
123 * The input data, either a host or an IP address
127 * True if a forward lookup is being performed, false if otherwise
131 * The DNS erver being used for lookups. If this is an empty string,
132 * the value of ServerConfig::DNSServer is used instead.
136 * The ID allocated to your lookup. This is a pseudo-random number
137 * between 0 and 65535, a value of -1 indicating a failure.
138 * The core uses this to route results to the correct objects.
143 * Initiate DNS lookup. Your class should not attempt to delete or free these
144 * objects, as the core will do this for you. They must always be created upon
145 * the heap using new, as you cannot be sure at what time they will be deleted.
146 * Allocating them on the stack or attempting to delete them yourself could cause
147 * the object to go 'out of scope' and cause a segfault in the core if the result
148 * arrives at a later time.
149 * @param source The IP or hostname to resolve
150 * @param qt The query type to perform. If you just want to perform a forward
151 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
152 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
153 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
154 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
155 * is supported. Use one of the QueryType enum values to initiate this type of
156 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
157 * wether InspIRCd is built with ipv6 support.
158 * If you attempt to resolve a 'PTR' record and InspIRCd is built with ipv6 support,
159 * the 'PTR' record will be formatted to ipv6 specs, e.g. x.x.x.x.x....ip6.int.
160 * otherwise it will be formatted to ipv4 specs, e.g. x.x.x.x.in-addr.arpa.
161 * @throw ModuleException This class may throw an instance of ModuleException, in the
162 * event a lookup could not be allocated, or a similar hard error occurs such as
163 * the network being down. This will also be thrown if an invalid IP address is
164 * passed when resolving a 'PTR' record.
166 Resolver(const std::string &source, QueryType qt);
168 * The default destructor does nothing.
172 * When your lookup completes, this method will be called.
173 * @param result The resulting DNS lookup, either an IP address or a hostname.
175 virtual void OnLookupComplete(const std::string &result) = 0;
177 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
179 * @param e A ResolverError enum containing the error type which has occured.
180 * @param errormessage The error text of the error that occured.
182 virtual void OnError(ResolverError e, const std::string &errormessage);
184 * Returns the id value of this class. This is primarily used by the core
185 * to determine where in various tables to place a pointer to your class, but it
186 * is safe to call and use this method.
187 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
188 * from 0 to 65535. If there is an issue and the core cannot send your request,
189 * this method will return -1.
194 /** DNS is a singleton class used by the core to dispatch dns
195 * requests to the dns server, and route incoming dns replies
196 * back to Resolver objects, based upon the request ID. You
197 * should never use this class yourself.
199 class DNS : public Extensible
204 * The maximum value of a dns request id,
205 * 16 bits wide, 0xFFFF.
207 static const int MAX_REQUEST_ID = 0xFFFF;
210 * Requests that are currently 'in flight'
212 requestlist requests;
215 * Server address being used currently
217 insp_inaddr myserver;
220 * File descriptor being used to perform queries
222 static int MasterSocket;
225 * A counter used to form part of the pseudo-random id
230 * Currently active Resolver classes
232 Resolver* Classes[MAX_REQUEST_ID];
235 * Build a dns packet payload
237 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
241 * The port number DNS requests are made on,
242 * and replies have as a source-port number.
244 static const int QUERY_PORT = 53;
247 * Fill an rr (resource record) with data from input
249 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
251 * Fill a header with data from input limited by a length
253 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
255 * Empty out a header into a data stream ready for transmission "on the wire"
257 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
259 * Get the master socket fd, used internally
261 static int GetMasterSocket();
264 * Start the lookup of an ipv4 from a hostname
266 int GetIP(const char* name);
269 * Start the lookup of a hostname from an ip
271 int GetName(const insp_inaddr* ip);
274 * Start lookup of an ipv6 from a hostname
276 int GetIP6(const char *name);
279 * Start lookup of a CNAME from another hostname
281 int GetCName(const char* alias);
284 * Fetch the result string (an ip or host)
285 * and/or an error message to go with it.
287 DNSResult GetResult();
290 * Handle a SocketEngine read event
292 void MarshallReads(int fd);
295 * Add a Resolver* to the list of active classes
297 bool AddResolverClass(Resolver* r);
300 * Add a query to the list to be sent
302 DNSRequest* AddQuery(DNSHeader *header, int &id);
305 * The constructor initialises the dns socket,
306 * and clears the request lists.
315 /** Portable random number generator, generates
316 * its random number from the ircd stats counters,
317 * effective user id, time of day and the rollover
320 unsigned long PRNG();