1 /* +------------------------------------+
2 * | Inspire Internet Relay Chat Daemon |
3 * +------------------------------------+
5 * InspIRCd: (C) 2002-2007 InspIRCd Development Team
6 * See: http://www.inspircd.org/wiki/index.php/Credits
8 * This program is free but copyrighted software; see
9 * the file COPYING for details.
11 * ---------------------------------------------------
15 dns.h - dns library very very loosely based on
16 firedns, Copyright (C) 2002 Ian Gulliver
18 This program is free software; you can redistribute it and/or modify
19 it under the terms of version 2 of the GNU General Public License as
20 published by the Free Software Foundation.
22 This program is distributed in the hope that it will be useful,
23 but WITHOUT ANY WARRANTY; without even the implied warranty of
24 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
25 GNU General Public License for more details.
27 You should have received a copy of the GNU General Public License
28 along with this program; if not, write to the Free Software
29 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
36 #include "inspircd_config.h"
38 #include "socketengine.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;
53 * Result status, used internally
55 class DNSResult : public classbase
63 DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig) : id(i), result(res), ttl(timetolive), original(orig) { }
67 * Information on a completed lookup, used internally
69 typedef std::pair<unsigned char*, std::string> DNSInfo;
79 CachedQuery(const std::string &res, unsigned int ttl) : data(res)
81 expires = time(NULL) + ttl;
84 int CalcTTLRemaining()
86 int n = expires - time(NULL);
87 return (n < 0 ? 0 : n);
91 /** DNS cache information
93 typedef nspace::hash_map<irc::string, CachedQuery, nspace::hash<irc::string> > dnscache;
96 * Error types that class Resolver can emit to its error method.
100 RESOLVER_NOERROR = 0,
102 RESOLVER_NXDOMAIN = 2,
103 RESOLVER_NOTREADY = 3,
105 RESOLVER_TIMEOUT = 5,
106 RESLOVER_FORCEUNLOAD = 6
115 * A DNS packet header
120 * A DNS Resource Record (rr)
122 class ResourceRecord;
125 * Query and resource record types
129 DNS_QUERY_NONE = 0, /* Uninitialized Query */
130 DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
131 DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
132 DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
133 DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
135 DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */
136 DNS_QUERY_PTR6 = 0xFFFE, /* Force 'PTR' to use IPV6 scemantics */
140 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
141 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
143 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
144 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
148 * Used internally to force PTR lookups to use a certain protocol scemantics,
149 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
153 PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */
154 PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */
158 * The Resolver class is a high-level abstraction for resolving DNS entries.
159 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
160 * also be able to do those, transparent of protocols. Module developers must
161 * extend this class via inheritence, and then insert a pointer to their derived
162 * class into the core using Server::AddResolver(). Once you have done this,
163 * the class will be able to receive callbacks. There are two callbacks which
164 * can occur by calling virtual methods, one is a success situation, and the other
165 * an error situation.
167 class Resolver : public Extensible
173 InspIRCd* ServerInstance;
175 * Pointer to creator module (if any, or NULL)
179 * The input data, either a host or an IP address
183 * True if a forward lookup is being performed, false if otherwise
187 * The DNS erver being used for lookups. If this is an empty string,
188 * the value of ServerConfig::DNSServer is used instead.
192 * The ID allocated to your lookup. This is a pseudo-random number
193 * between 0 and 65535, a value of -1 indicating a failure.
194 * The core uses this to route results to the correct objects.
199 * Cached result, if there is one
204 * Time left before cache expiry
209 * Initiate DNS lookup. Your class should not attempt to delete or free these
210 * objects, as the core will do this for you. They must always be created upon
211 * the heap using new, as you cannot be sure at what time they will be deleted.
212 * Allocating them on the stack or attempting to delete them yourself could cause
213 * the object to go 'out of scope' and cause a segfault in the core if the result
214 * arrives at a later time.
215 * @param source The IP or hostname to resolve
216 * @param qt The query type to perform. If you just want to perform a forward
217 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
218 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
219 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
220 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
221 * is supported. Use one of the QueryType enum values to initiate this type of
222 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
223 * wether InspIRCd is built with ipv6 support.
224 * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
225 * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
226 * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
227 * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
228 * To get around this automatic behaviour, you must use one of the values
229 * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
230 * irrespective of what protocol InspIRCd has been built for.
231 * @throw ModuleException This class may throw an instance of ModuleException, in the
232 * event a lookup could not be allocated, or a similar hard error occurs such as
233 * the network being down. This will also be thrown if an invalid IP address is
234 * passed when resolving a 'PTR' record.
236 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
237 * value of creator to point at your Module class. This way if your module is unloaded
238 * whilst lookups are in progress, they can be safely removed and your module will not
241 Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, bool &cached, Module* creator = NULL);
244 * The default destructor does nothing.
248 * When your lookup completes, this method will be called.
249 * @param result The resulting DNS lookup, either an IP address or a hostname.
251 virtual void OnLookupComplete(const std::string &result, unsigned int ttl) = 0;
253 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
255 * @param e A ResolverError enum containing the error type which has occured.
256 * @param errormessage The error text of the error that occured.
258 virtual void OnError(ResolverError e, const std::string &errormessage);
260 * Returns the id value of this class. This is primarily used by the core
261 * to determine where in various tables to place a pointer to your class, but it
262 * is safe to call and use this method.
263 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
264 * from 0 to 65535. If there is an issue and the core cannot send your request,
265 * this method will return -1.
270 * Returns the creator module, or NULL
272 Module* GetCreator();
274 void TriggerCachedResult();
277 /** DNS is a singleton class used by the core to dispatch dns
278 * requests to the dns server, and route incoming dns replies
279 * back to Resolver objects, based upon the request ID. You
280 * should never use this class yourself.
282 class DNS : public EventHandler
286 InspIRCd* ServerInstance;
289 * The maximum value of a dns request id,
290 * 16 bits wide, 0xFFFF.
292 static const int MAX_REQUEST_ID = 0xFFFF;
295 * Server address being used currently
297 insp_inaddr myserver;
300 * A counter used to form part of the pseudo-random id
305 * We have to turn off a few checks on received packets
306 * when people are using 4in6 (e.g. ::ffff:xxxx). This is
307 * a temporary kludge, Please let me know if you know how
313 * Currently cached items
318 * Build a dns packet payload
320 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
324 * Currently active Resolver classes
326 Resolver* Classes[MAX_REQUEST_ID];
328 * Requests that are currently 'in flight'
330 DNSRequest* requests[MAX_REQUEST_ID];
332 * The port number DNS requests are made on,
333 * and replies have as a source-port number.
335 static const int QUERY_PORT = 53;
338 * Fill an rr (resource record) with data from input
340 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
342 * Fill a header with data from input limited by a length
344 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
346 * Empty out a header into a data stream ready for transmission "on the wire"
348 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
350 * Start the lookup of an ipv4 from a hostname
352 int GetIP(const char* name);
355 * Start the lookup of a hostname from an ip,
356 * always using the protocol inspircd is built for,
357 * e.g. use ipv6 reverse lookup when built for ipv6,
358 * or ipv4 lookup when built for ipv4.
360 int GetName(const insp_inaddr* ip);
363 * Start lookup of a hostname from an ip, but
364 * force a specific protocol to be used for the lookup
365 * for example to perform an ipv6 reverse lookup.
367 int GetNameForce(const char *ip, ForceProtocol fp);
370 * Start lookup of an ipv6 from a hostname
372 int GetIP6(const char *name);
375 * Start lookup of a CNAME from another hostname
377 int GetCName(const char* alias);
380 * Fetch the result string (an ip or host)
381 * and/or an error message to go with it.
383 DNSResult GetResult();
386 * Handle a SocketEngine read event
387 * Inherited from EventHandler
389 void HandleEvent(EventType et, int errornum = 0);
392 * Add a Resolver* to the list of active classes
394 bool AddResolverClass(Resolver* r);
397 * Add a query to the list to be sent
399 DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
402 * The constructor initialises the dns socket,
403 * and clears the request lists.
405 DNS(InspIRCd* Instance);
408 * Re-initialize the DNS subsystem.
417 /** Portable random number generator, generates
418 * its random number from the ircd stats counters,
419 * effective user id, time of day and the rollover
422 unsigned long PRNG();
425 * Turn an in6_addr into a .ip6.arpa domain
427 static void MakeIP6Int(char* query, const in6_addr *ip);
430 * Clean out all dns resolvers owned by a particular
431 * module, to make unloading a module safe if there
432 * are dns requests currently in progress.
434 void CleanResolvers(Module* module);
436 CachedQuery* GetCache(const std::string &source);
438 void DelCache(const std::string &source);