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 * Query and resource record types
51 /** Uninitialized Query */
53 /** 'A' record: an ipv4 address */
55 /** 'CNAME' record: An alias */
57 /** 'PTR' record: a hostname */
59 /** 'AAAA' record: an ipv6 address */
62 /** Force 'PTR' to use IPV4 scemantics */
63 DNS_QUERY_PTR4 = 0xFFFD,
64 /** Force 'PTR' to use IPV6 scemantics */
65 DNS_QUERY_PTR6 = 0xFFFE
69 * Result status, used internally
71 class CoreExport DNSResult
77 /** Result body, a hostname or IP address
80 /** Time-to-live value of the result
83 /** The original request, a hostname or IP address
86 /** The type of the request
90 /** Build a DNS result.
91 * @param i The request ID
92 * @param res The request result, a hostname or IP
93 * @param timetolive The request time-to-live
94 * @param orig The original request, a hostname or IP
95 * @param qt The type of DNS query this result represents.
97 DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig, QueryType qt = DNS_QUERY_NONE) : id(i), result(res), ttl(timetolive), original(orig), type(qt) { }
101 * Information on a completed lookup, used internally
103 typedef std::pair<unsigned char*, std::string> DNSInfo;
105 /** Cached item stored in the query cache.
107 class CoreExport CachedQuery
110 /** The cached result data, an IP or hostname
113 /** The type of result this is
116 /** The time when the item is due to expire
120 /** Build a cached query
121 * @param res The result data, an IP or hostname
122 * @param qt The type of DNS query this instance represents.
123 * @param ttl The time-to-live value of the query result
125 CachedQuery(const std::string &res, QueryType qt, unsigned int ttl);
127 /** Returns the number of seconds remaining before this
128 * cache item has expired and should be removed.
130 int CalcTTLRemaining();
133 /** DNS cache information. Holds IPs mapped to hostnames, and hostnames mapped to IPs.
135 typedef nspace::hash_map<irc::string, CachedQuery, irc::hash> dnscache;
138 * Error types that class Resolver can emit to its error method.
142 RESOLVER_NOERROR = 0,
144 RESOLVER_NXDOMAIN = 2,
146 RESOLVER_TIMEOUT = 4,
147 RESOLVER_FORCEUNLOAD = 5
151 * Used internally to force PTR lookups to use a certain protocol scemantics,
152 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
156 /** Forced to use ipv4 */
158 /** Forced to use ipv6 */
163 * The Resolver class is a high-level abstraction for resolving DNS entries.
164 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
165 * also be able to do those, transparent of protocols. Module developers must
166 * extend this class via inheritence, and then insert a pointer to their derived
167 * class into the core using Server::AddResolver(). Once you have done this,
168 * the class will be able to receive callbacks. There are two callbacks which
169 * can occur by calling virtual methods, one is a success situation, and the other
170 * an error situation.
172 class CoreExport Resolver
176 * Pointer to creator module (if any, or NULL)
180 * The input data, either a host or an IP address
184 * True if a forward lookup is being performed, false if otherwise
188 * The DNS erver being used for lookups. If this is an empty string,
189 * the value of ServerConfig::DNSServer is used instead.
193 * The ID allocated to your lookup. This is a pseudo-random number
194 * between 0 and 65535, a value of -1 indicating a failure.
195 * The core uses this to route results to the correct objects.
200 * Cached result, if there is one
205 * Time left before cache expiry
211 * Initiate DNS lookup. Your class should not attempt to delete or free these
212 * objects, as the core will do this for you. They must always be created upon
213 * the heap using new, as you cannot be sure at what time they will be deleted.
214 * Allocating them on the stack or attempting to delete them yourself could cause
215 * the object to go 'out of scope' and cause a segfault in the core if the result
216 * arrives at a later time.
217 * @param source The IP or hostname to resolve
218 * @param qt The query type to perform. Resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
219 * is supported. Use one of the QueryType enum values to initiate this type of
220 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
221 * wether InspIRCd is built with ipv6 support.
222 * To look up reverse records, specify one of DNS_QUERY_PTR4 or DNS_QUERY_PTR6 depending
223 * on the type of address you are looking up.
224 * @param cached The constructor will set this boolean to true or false depending
225 * on whether the DNS lookup you are attempting is cached (and not expired) or not.
226 * If the value is cached, upon return this will be set to true, otherwise it will
227 * be set to false. You should pass this value to InspIRCd::AddResolver(), which
228 * will then influence the behaviour of the method and determine whether a cached
229 * or non-cached result is obtained. The value in this variable is always correct
230 * for the given request when the constructor exits.
231 * @param creator See the note below.
232 * @throw ModuleException This class may throw an instance of ModuleException, in the
233 * event a lookup could not be allocated, or a similar hard error occurs such as
234 * the network being down. This will also be thrown if an invalid IP address is
235 * passed when resolving a 'PTR' record.
237 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
238 * value of creator to point at your Module class. This way if your module is unloaded
239 * whilst lookups are in progress, they can be safely removed and your module will not
242 Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator);
245 * The default destructor does nothing.
250 * When your lookup completes, this method will be called.
251 * @param result The resulting DNS lookup, either an IP address or a hostname.
252 * @param ttl The time-to-live value of the result, in the instance of a cached
253 * result, this is the number of seconds remaining before refresh/expiry.
254 * @param cached True if the result is a cached result, false if it was requested
255 * from the DNS server.
257 virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached) = 0;
260 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
262 * @param e A ResolverError enum containing the error type which has occured.
263 * @param errormessage The error text of the error that occured.
265 virtual void OnError(ResolverError e, const std::string &errormessage);
268 * Returns the id value of this class. This is primarily used by the core
269 * to determine where in various tables to place a pointer to your class, but it
270 * is safe to call and use this method.
271 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
272 * from 0 to 65535. If there is an issue and the core cannot send your request,
273 * this method will return -1.
278 * Returns the creator module, or NULL
280 Module* GetCreator();
283 * If the result is a cached result, this triggers the objects
284 * OnLookupComplete. This is done because it is not safe to call
285 * the abstract virtual method from the constructor.
287 void TriggerCachedResult();
290 /** DNS is a singleton class used by the core to dispatch dns
291 * requests to the dns server, and route incoming dns replies
292 * back to Resolver objects, based upon the request ID. You
293 * should never use this class yourself.
295 class CoreExport DNS : public EventHandler
300 * The maximum value of a dns request id,
301 * 16 bits wide, 0xFFFF.
303 static const int MAX_REQUEST_ID = 0xFFFF;
306 * Currently cached items
310 /** A timer which ticks every hour to remove expired
311 * items from the DNS cache.
313 class CacheTimer* PruneTimer;
316 * Build a dns packet payload
318 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
322 irc::sockets::sockaddrs myserver;
325 * Currently active Resolver classes
327 Resolver* Classes[MAX_REQUEST_ID];
330 * Requests that are currently 'in flight'
332 DNSRequest* requests[MAX_REQUEST_ID];
335 * The port number DNS requests are made on,
336 * and replies have as a source-port number.
338 static const int QUERY_PORT = 53;
341 * Fill an rr (resource record) with data from input
343 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
346 * Fill a header with data from input limited by a length
348 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
351 * Empty out a header into a data stream ready for transmission "on the wire"
353 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
356 * Start the lookup of an ipv4 from a hostname
358 int GetIP(const char* name);
361 * Start lookup of a hostname from an ip, but
362 * force a specific protocol to be used for the lookup
363 * for example to perform an ipv6 reverse lookup.
365 int GetNameForce(const char *ip, ForceProtocol fp);
368 * Start lookup of an ipv6 from a hostname
370 int GetIP6(const char *name);
373 * Start lookup of a CNAME from another hostname
375 int GetCName(const char* alias);
378 * Fetch the result string (an ip or host)
379 * and/or an error message to go with it.
381 DNSResult GetResult();
384 * Handle a SocketEngine read event
385 * Inherited from EventHandler
387 void HandleEvent(EventType et, int errornum = 0);
390 * Add a Resolver* to the list of active classes
392 bool AddResolverClass(Resolver* r);
395 * Add a query to the list to be sent
397 DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
400 * The constructor initialises the dns socket,
401 * and clears the request lists.
406 * Re-initialize the DNS subsystem.
416 * Turn an in6_addr into a .ip6.arpa domain
418 static void MakeIP6Int(char* query, const in6_addr *ip);
421 * Clean out all dns resolvers owned by a particular
422 * module, to make unloading a module safe if there
423 * are dns requests currently in progress.
425 void CleanResolvers(Module* module);
427 /** Return the cached value of an IP or hostname
428 * @param source An IP or hostname to find in the cache.
429 * @return A pointer to a CachedQuery if the item exists,
432 CachedQuery* GetCache(const std::string &source);
434 /** Delete a cached item from the DNS cache.
435 * @param source An IP or hostname to remove
437 void DelCache(const std::string &source);
439 /** Clear all items from the DNS cache immediately.
443 /** Prune the DNS cache, e.g. remove all expired
444 * items and rehash the cache buckets, but leave
445 * items in the hash which are still valid.