2 * InspIRCd -- Internet Relay Chat Daemon
4 * Copyright (C) 2009 Daniel De Graaf <danieldg@inspircd.org>
5 * Copyright (C) 2005-2008 Craig Edwards <craigedwards@brainbox.cc>
6 * Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
8 * This file is part of InspIRCd. InspIRCd is free software: you can
9 * redistribute it and/or modify it under the terms of the GNU General Public
10 * License as published by the Free Software Foundation, version 2.
12 * This program is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
14 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
17 * You should have received a copy of the GNU General Public License
18 * along with this program. If not, see <http://www.gnu.org/licenses/>.
23 dns.h - dns library very very loosely based on
24 firedns, Copyright (C) 2002 Ian Gulliver
26 This program is free software; you can redistribute it and/or modify
27 it under the terms of version 2 of the GNU General Public License as
28 published by the Free Software Foundation.
30 This program is distributed in the hope that it will be useful,
31 but WITHOUT ANY WARRANTY; without even the implied warranty of
32 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
33 GNU General Public License for more details.
35 You should have received a copy of the GNU General Public License
36 along with this program; if not, write to the Free Software
37 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
47 * Result status, used internally
49 class CoreExport DNSResult
55 /** Result body, a hostname or IP address
58 /** Time-to-live value of the result
61 /** The original request, a hostname or IP address
65 /** Build a DNS result.
66 * @param i The request ID
67 * @param res The request result, a hostname or IP
68 * @param timetolive The request time-to-live
69 * @param orig The original request, a hostname or IP
71 DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig) : id(i), result(res), ttl(timetolive), original(orig) { }
75 * Information on a completed lookup, used internally
77 typedef std::pair<unsigned char*, std::string> DNSInfo;
79 /** Cached item stored in the query cache.
81 class CoreExport CachedQuery
84 /** The cached result data, an IP or hostname
87 /** The time when the item is due to expire
91 /** Build a cached query
92 * @param res The result data, an IP or hostname
93 * @param ttl The time-to-live value of the query result
95 CachedQuery(const std::string &res, unsigned int ttl);
97 /** Returns the number of seconds remaining before this
98 * cache item has expired and should be removed.
100 int CalcTTLRemaining();
103 /** DNS cache information. Holds IPs mapped to hostnames, and hostnames mapped to IPs.
105 typedef nspace::hash_map<irc::string, CachedQuery, irc::hash> dnscache;
108 * Error types that class Resolver can emit to its error method.
112 RESOLVER_NOERROR = 0,
114 RESOLVER_NXDOMAIN = 2,
116 RESOLVER_TIMEOUT = 4,
117 RESOLVER_FORCEUNLOAD = 5
121 * Query and resource record types
125 /** Uninitialized Query */
127 /** 'A' record: an ipv4 address */
129 /** 'CNAME' record: An alias */
131 /** 'PTR' record: a hostname */
133 /** 'AAAA' record: an ipv6 address */
136 /** Force 'PTR' to use IPV4 scemantics */
137 DNS_QUERY_PTR4 = 0xFFFD,
138 /** Force 'PTR' to use IPV6 scemantics */
139 DNS_QUERY_PTR6 = 0xFFFE
143 * Used internally to force PTR lookups to use a certain protocol scemantics,
144 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
148 /** Forced to use ipv4 */
150 /** Forced to use ipv6 */
155 * The Resolver class is a high-level abstraction for resolving DNS entries.
156 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
157 * also be able to do those, transparent of protocols. Module developers must
158 * extend this class via inheritence, and then insert a pointer to their derived
159 * class into the core using Server::AddResolver(). Once you have done this,
160 * the class will be able to receive callbacks. There are two callbacks which
161 * can occur by calling virtual methods, one is a success situation, and the other
162 * an error situation.
164 class CoreExport Resolver
168 * Pointer to creator module (if any, or NULL)
172 * The input data, either a host or an IP address
176 * True if a forward lookup is being performed, false if otherwise
180 * The DNS erver being used for lookups. If this is an empty string,
181 * the value of ServerConfig::DNSServer is used instead.
185 * The ID allocated to your lookup. This is a pseudo-random number
186 * between 0 and 65535, a value of -1 indicating a failure.
187 * The core uses this to route results to the correct objects.
192 * Cached result, if there is one
197 * Time left before cache expiry
203 * Initiate DNS lookup. Your class should not attempt to delete or free these
204 * objects, as the core will do this for you. They must always be created upon
205 * the heap using new, as you cannot be sure at what time they will be deleted.
206 * Allocating them on the stack or attempting to delete them yourself could cause
207 * the object to go 'out of scope' and cause a segfault in the core if the result
208 * arrives at a later time.
209 * @param source The IP or hostname to resolve
210 * @param qt The query type to perform. Resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
211 * is supported. Use one of the QueryType enum values to initiate this type of
212 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
213 * wether InspIRCd is built with ipv6 support.
214 * To look up reverse records, specify one of DNS_QUERY_PTR4 or DNS_QUERY_PTR6 depending
215 * on the type of address you are looking up.
216 * @param cached The constructor will set this boolean to true or false depending
217 * on whether the DNS lookup you are attempting is cached (and not expired) or not.
218 * If the value is cached, upon return this will be set to true, otherwise it will
219 * be set to false. You should pass this value to InspIRCd::AddResolver(), which
220 * will then influence the behaviour of the method and determine whether a cached
221 * or non-cached result is obtained. The value in this variable is always correct
222 * for the given request when the constructor exits.
223 * @param creator See the note below.
224 * @throw ModuleException This class may throw an instance of ModuleException, in the
225 * event a lookup could not be allocated, or a similar hard error occurs such as
226 * the network being down. This will also be thrown if an invalid IP address is
227 * passed when resolving a 'PTR' record.
229 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
230 * value of creator to point at your Module class. This way if your module is unloaded
231 * whilst lookups are in progress, they can be safely removed and your module will not
234 Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator);
237 * The default destructor does nothing.
242 * When your lookup completes, this method will be called.
243 * @param result The resulting DNS lookup, either an IP address or a hostname.
244 * @param ttl The time-to-live value of the result, in the instance of a cached
245 * result, this is the number of seconds remaining before refresh/expiry.
246 * @param cached True if the result is a cached result, false if it was requested
247 * from the DNS server.
249 virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached) = 0;
252 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
254 * @param e A ResolverError enum containing the error type which has occured.
255 * @param errormessage The error text of the error that occured.
257 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();
275 * If the result is a cached result, this triggers the objects
276 * OnLookupComplete. This is done because it is not safe to call
277 * the abstract virtual method from the constructor.
279 void TriggerCachedResult();
282 /** DNS is a singleton class used by the core to dispatch dns
283 * requests to the dns server, and route incoming dns replies
284 * back to Resolver objects, based upon the request ID. You
285 * should never use this class yourself.
287 class CoreExport DNS : public EventHandler
292 * The maximum value of a dns request id,
293 * 16 bits wide, 0xFFFF.
295 static const int MAX_REQUEST_ID = 0xFFFF;
298 * Currently cached items
302 /** A timer which ticks every hour to remove expired
303 * items from the DNS cache.
305 class CacheTimer* PruneTimer;
308 * Build a dns packet payload
310 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
314 irc::sockets::sockaddrs myserver;
317 * Currently active Resolver classes
319 Resolver* Classes[MAX_REQUEST_ID];
322 * Requests that are currently 'in flight'
324 DNSRequest* requests[MAX_REQUEST_ID];
327 * The port number DNS requests are made on,
328 * and replies have as a source-port number.
330 static const int QUERY_PORT = 53;
333 * Fill an rr (resource record) with data from input
335 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
338 * Fill a header with data from input limited by a length
340 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
343 * Empty out a header into a data stream ready for transmission "on the wire"
345 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
348 * Start the lookup of an ipv4 from a hostname
350 int GetIP(const char* name);
353 * Start lookup of a hostname from an ip, but
354 * force a specific protocol to be used for the lookup
355 * for example to perform an ipv6 reverse lookup.
357 int GetNameForce(const char *ip, ForceProtocol fp);
360 * Start lookup of an ipv6 from a hostname
362 int GetIP6(const char *name);
365 * Start lookup of a CNAME from another hostname
367 int GetCName(const char* alias);
370 * Fetch the result string (an ip or host)
371 * and/or an error message to go with it.
373 DNSResult GetResult();
376 * Handle a SocketEngine read event
377 * Inherited from EventHandler
379 void HandleEvent(EventType et, int errornum = 0);
382 * Add a Resolver* to the list of active classes
384 bool AddResolverClass(Resolver* r);
387 * Add a query to the list to be sent
389 DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
392 * The constructor initialises the dns socket,
393 * and clears the request lists.
398 * Re-initialize the DNS subsystem.
408 * Turn an in6_addr into a .ip6.arpa domain
410 static void MakeIP6Int(char* query, const in6_addr *ip);
413 * Clean out all dns resolvers owned by a particular
414 * module, to make unloading a module safe if there
415 * are dns requests currently in progress.
417 void CleanResolvers(Module* module);
419 /** Return the cached value of an IP or hostname
420 * @param source An IP or hostname to find in the cache.
421 * @return A pointer to a CachedQuery if the item exists,
424 CachedQuery* GetCache(const std::string &source);
426 /** Delete a cached item from the DNS cache.
427 * @param source An IP or hostname to remove
429 void DelCache(const std::string &source);
431 /** Clear all items from the DNS cache immediately.
435 /** Prune the DNS cache, e.g. remove all expired
436 * items and rehash the cache buckets, but leave
437 * items in the hash which are still valid.