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 using irc::sockets::insp_aton;
45 using irc::sockets::insp_ntoa;
46 using irc::sockets::insp_sockaddr;
47 using irc::sockets::insp_inaddr;
52 * Result status, used internally
54 typedef std::pair<int,std::string> DNSResult;
57 * Information on a completed lookup, used internally
59 typedef std::pair<unsigned char*, std::string> DNSInfo;
62 * Error types that class Resolver can emit to its error method.
68 RESOLVER_NXDOMAIN = 2,
69 RESOLVER_NOTREADY = 3,
84 * A DNS Resource Record (rr)
89 * A set of requests keyed by request id
91 typedef std::map<int,DNSRequest*> requestlist;
94 * An iterator into a set of requests
96 typedef requestlist::iterator requestlist_iter;
99 * Query and resource record types
103 DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
104 DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
105 DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
106 DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
108 DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */
109 DNS_QUERY_PTR6 = 0xFFFE, /* Force 'PTR' to use IPV6 scemantics */
113 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
114 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
116 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
117 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
121 * Used internally to force PTR lookups to use a certain protocol scemantics,
122 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
126 PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */
127 PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */
131 * The Resolver class is a high-level abstraction for resolving DNS entries.
132 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
133 * also be able to do those, transparent of protocols. Module developers must
134 * extend this class via inheritence, and then insert a pointer to their derived
135 * class into the core using Server::AddResolver(). Once you have done this,
136 * the class will be able to receive callbacks. There are two callbacks which
137 * can occur by calling virtual methods, one is a success situation, and the other
138 * an error situation.
140 class Resolver : public Extensible
146 InspIRCd* ServerInstance;
148 * The input data, either a host or an IP address
152 * True if a forward lookup is being performed, false if otherwise
156 * The DNS erver being used for lookups. If this is an empty string,
157 * the value of ServerConfig::DNSServer is used instead.
161 * The ID allocated to your lookup. This is a pseudo-random number
162 * between 0 and 65535, a value of -1 indicating a failure.
163 * The core uses this to route results to the correct objects.
168 * Initiate DNS lookup. Your class should not attempt to delete or free these
169 * objects, as the core will do this for you. They must always be created upon
170 * the heap using new, as you cannot be sure at what time they will be deleted.
171 * Allocating them on the stack or attempting to delete them yourself could cause
172 * the object to go 'out of scope' and cause a segfault in the core if the result
173 * arrives at a later time.
174 * @param source The IP or hostname to resolve
175 * @param qt The query type to perform. If you just want to perform a forward
176 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
177 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
178 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
179 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
180 * is supported. Use one of the QueryType enum values to initiate this type of
181 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
182 * wether InspIRCd is built with ipv6 support.
183 * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
184 * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
185 * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
186 * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
187 * To get around this automatic behaviour, you must use one of the values
188 * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
189 * irrespective of what protocol InspIRCd has been built for.
190 * @throw ModuleException This class may throw an instance of ModuleException, in the
191 * event a lookup could not be allocated, or a similar hard error occurs such as
192 * the network being down. This will also be thrown if an invalid IP address is
193 * passed when resolving a 'PTR' record.
195 Resolver(InspIRCd* Instance, const std::string &source, QueryType qt);
197 * The default destructor does nothing.
201 * When your lookup completes, this method will be called.
202 * @param result The resulting DNS lookup, either an IP address or a hostname.
204 virtual void OnLookupComplete(const std::string &result) = 0;
206 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
208 * @param e A ResolverError enum containing the error type which has occured.
209 * @param errormessage The error text of the error that occured.
211 virtual void OnError(ResolverError e, const std::string &errormessage);
213 * Returns the id value of this class. This is primarily used by the core
214 * to determine where in various tables to place a pointer to your class, but it
215 * is safe to call and use this method.
216 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
217 * from 0 to 65535. If there is an issue and the core cannot send your request,
218 * this method will return -1.
223 /** DNS is a singleton class used by the core to dispatch dns
224 * requests to the dns server, and route incoming dns replies
225 * back to Resolver objects, based upon the request ID. You
226 * should never use this class yourself.
228 class DNS : public Extensible
232 InspIRCd* ServerInstance;
235 * The maximum value of a dns request id,
236 * 16 bits wide, 0xFFFF.
238 static const int MAX_REQUEST_ID = 0xFFFF;
241 * Requests that are currently 'in flight'
243 requestlist requests;
246 * Server address being used currently
248 insp_inaddr myserver;
251 * File descriptor being used to perform queries
253 static int MasterSocket;
256 * A counter used to form part of the pseudo-random id
261 * Currently active Resolver classes
263 Resolver* Classes[MAX_REQUEST_ID];
266 * We have to turn off a few checks on received packets
267 * when people are using 4in6 (e.g. ::ffff:xxxx). This is
268 * a temporary kludge, Please let me know if you know how
274 * Build a dns packet payload
276 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
280 * The port number DNS requests are made on,
281 * and replies have as a source-port number.
283 static const int QUERY_PORT = 53;
286 * Fill an rr (resource record) with data from input
288 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
290 * Fill a header with data from input limited by a length
292 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
294 * Empty out a header into a data stream ready for transmission "on the wire"
296 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
298 * Get the master socket fd, used internally
300 static int GetMasterSocket();
303 * Start the lookup of an ipv4 from a hostname
305 int GetIP(const char* name);
308 * Start the lookup of a hostname from an ip,
309 * always using the protocol inspircd is built for,
310 * e.g. use ipv6 reverse lookup when built for ipv6,
311 * or ipv4 lookup when built for ipv4.
313 int GetName(const insp_inaddr* ip);
316 * Start lookup of a hostname from an ip, but
317 * force a specific protocol to be used for the lookup
318 * for example to perform an ipv6 reverse lookup.
320 int GetNameForce(const char *ip, ForceProtocol fp);
323 * Start lookup of an ipv6 from a hostname
325 int GetIP6(const char *name);
328 * Start lookup of a CNAME from another hostname
330 int GetCName(const char* alias);
333 * Fetch the result string (an ip or host)
334 * and/or an error message to go with it.
336 DNSResult GetResult();
339 * Handle a SocketEngine read event
341 void MarshallReads(int fd);
344 * Add a Resolver* to the list of active classes
346 bool AddResolverClass(Resolver* r);
349 * Add a query to the list to be sent
351 DNSRequest* AddQuery(DNSHeader *header, int &id);
354 * The constructor initialises the dns socket,
355 * and clears the request lists.
357 DNS(InspIRCd* Instance);
364 /** Portable random number generator, generates
365 * its random number from the ircd stats counters,
366 * effective user id, time of day and the rollover
369 unsigned long PRNG();
372 * Turn an in6_addr into a .ip6.arpa domain
374 static void MakeIP6Int(char* query, const in6_addr *ip);