1 /* +------------------------------------+
2 * | Inspire Internet Relay Chat Daemon |
3 * +------------------------------------+
5 * InspIRCd: (C) 2002-2009 InspIRCd Development Team
6 * See: http://wiki.inspircd.org/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
41 * Result status, used internally
43 class CoreExport DNSResult : public classbase
49 /** Result body, a hostname or IP address
52 /** Time-to-live value of the result
55 /** The original request, a hostname or IP address
59 /** Build a DNS result.
60 * @param i The request ID
61 * @param res The request result, a hostname or IP
62 * @param timetolive The request time-to-live
63 * @param orig The original request, a hostname or IP
65 DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig) : id(i), result(res), ttl(timetolive), original(orig) { }
69 * Information on a completed lookup, used internally
71 typedef std::pair<unsigned char*, std::string> DNSInfo;
73 /** Cached item stored in the query cache.
75 class CoreExport CachedQuery : public classbase
78 /** The cached result data, an IP or hostname
81 /** The time when the item is due to expire
85 /** Build a cached query
86 * @param res The result data, an IP or hostname
87 * @param ttl The time-to-live value of the query result
89 CachedQuery(const std::string &res, unsigned int ttl) : data(res)
91 expires = time(NULL) + ttl;
94 /** Returns the number of seconds remaining before this
95 * cache item has expired and should be removed.
97 int CalcTTLRemaining()
99 int n = (int)expires - (int)time(NULL);
100 return (n < 0 ? 0 : n);
104 /** DNS cache information. Holds IPs mapped to hostnames, and hostnames mapped to IPs.
106 #if defined(WINDOWS) && !defined(HASHMAP_DEPRECATED)
107 typedef nspace::hash_map<irc::string, CachedQuery, nspace::hash_compare<irc::string> > dnscache;
109 typedef nspace::hash_map<irc::string, CachedQuery, nspace::hash<irc::string> > dnscache;
113 * Error types that class Resolver can emit to its error method.
117 RESOLVER_NOERROR = 0,
119 RESOLVER_NXDOMAIN = 2,
121 RESOLVER_TIMEOUT = 4,
122 RESOLVER_FORCEUNLOAD = 5
131 * A DNS packet header
136 * A DNS Resource Record (rr)
138 struct ResourceRecord;
141 * Query and resource record types
145 /** Uninitialized Query */
147 /** 'A' record: an ipv4 address */
149 /** 'CNAME' record: An alias */
151 /** 'PTR' record: a hostname */
153 /** 'AAAA' record: an ipv6 address */
156 /** Force 'PTR' to use IPV4 scemantics */
157 DNS_QUERY_PTR4 = 0xFFFD,
158 /** Force 'PTR' to use IPV6 scemantics */
159 DNS_QUERY_PTR6 = 0xFFFE
163 * Used internally to force PTR lookups to use a certain protocol scemantics,
164 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
168 /** Forced to use ipv4 */
170 /** Forced to use ipv6 */
175 * The Resolver class is a high-level abstraction for resolving DNS entries.
176 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
177 * also be able to do those, transparent of protocols. Module developers must
178 * extend this class via inheritence, and then insert a pointer to their derived
179 * class into the core using Server::AddResolver(). Once you have done this,
180 * the class will be able to receive callbacks. There are two callbacks which
181 * can occur by calling virtual methods, one is a success situation, and the other
182 * an error situation.
184 class CoreExport Resolver : public Extensible
188 * Pointer to creator module (if any, or NULL)
192 * The input data, either a host or an IP address
196 * True if a forward lookup is being performed, false if otherwise
200 * The DNS erver being used for lookups. If this is an empty string,
201 * the value of ServerConfig::DNSServer is used instead.
205 * The ID allocated to your lookup. This is a pseudo-random number
206 * between 0 and 65535, a value of -1 indicating a failure.
207 * The core uses this to route results to the correct objects.
212 * Cached result, if there is one
217 * Time left before cache expiry
223 * Initiate DNS lookup. Your class should not attempt to delete or free these
224 * objects, as the core will do this for you. They must always be created upon
225 * the heap using new, as you cannot be sure at what time they will be deleted.
226 * Allocating them on the stack or attempting to delete them yourself could cause
227 * the object to go 'out of scope' and cause a segfault in the core if the result
228 * arrives at a later time.
229 * @param source The IP or hostname to resolve
230 * @param qt The query type to perform. Resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
231 * is supported. Use one of the QueryType enum values to initiate this type of
232 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
233 * wether InspIRCd is built with ipv6 support.
234 * To look up reverse records, specify one of DNS_QUERY_PTR4 or DNS_QUERY_PTR6 depending
235 * on the type of address you are looking up.
236 * @param cached The constructor will set this boolean to true or false depending
237 * on whether the DNS lookup you are attempting is cached (and not expired) or not.
238 * If the value is cached, upon return this will be set to true, otherwise it will
239 * be set to false. You should pass this value to InspIRCd::AddResolver(), which
240 * will then influence the behaviour of the method and determine whether a cached
241 * or non-cached result is obtained. The value in this variable is always correct
242 * for the given request when the constructor exits.
243 * @param creator See the note below.
244 * @throw ModuleException This class may throw an instance of ModuleException, in the
245 * event a lookup could not be allocated, or a similar hard error occurs such as
246 * the network being down. This will also be thrown if an invalid IP address is
247 * passed when resolving a 'PTR' record.
249 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
250 * value of creator to point at your Module class. This way if your module is unloaded
251 * whilst lookups are in progress, they can be safely removed and your module will not
254 Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator = NULL);
257 * The default destructor does nothing.
262 * When your lookup completes, this method will be called.
263 * @param result The resulting DNS lookup, either an IP address or a hostname.
264 * @param ttl The time-to-live value of the result, in the instance of a cached
265 * result, this is the number of seconds remaining before refresh/expiry.
266 * @param cached True if the result is a cached result, false if it was requested
267 * from the DNS server.
269 virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached) = 0;
272 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
274 * @param e A ResolverError enum containing the error type which has occured.
275 * @param errormessage The error text of the error that occured.
277 virtual void OnError(ResolverError e, const std::string &errormessage);
280 * Returns the id value of this class. This is primarily used by the core
281 * to determine where in various tables to place a pointer to your class, but it
282 * is safe to call and use this method.
283 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
284 * from 0 to 65535. If there is an issue and the core cannot send your request,
285 * this method will return -1.
290 * Returns the creator module, or NULL
292 Module* GetCreator();
295 * If the result is a cached result, this triggers the objects
296 * OnLookupComplete. This is done because it is not safe to call
297 * the abstract virtual method from the constructor.
299 void TriggerCachedResult();
302 /** DNS is a singleton class used by the core to dispatch dns
303 * requests to the dns server, and route incoming dns replies
304 * back to Resolver objects, based upon the request ID. You
305 * should never use this class yourself.
307 class CoreExport DNS : public EventHandler
312 * The maximum value of a dns request id,
313 * 16 bits wide, 0xFFFF.
315 static const int MAX_REQUEST_ID = 0xFFFF;
318 * A counter used to form part of the pseudo-random id
323 * Currently cached items
327 /** A timer which ticks every hour to remove expired
328 * items from the DNS cache.
330 class CacheTimer* PruneTimer;
333 * Build a dns packet payload
335 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
339 irc::sockets::sockaddrs myserver;
342 * Currently active Resolver classes
344 Resolver* Classes[MAX_REQUEST_ID];
347 * Requests that are currently 'in flight'
349 DNSRequest* requests[MAX_REQUEST_ID];
352 * The port number DNS requests are made on,
353 * and replies have as a source-port number.
355 static const int QUERY_PORT = 53;
358 * Fill an rr (resource record) with data from input
360 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
363 * Fill a header with data from input limited by a length
365 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
368 * Empty out a header into a data stream ready for transmission "on the wire"
370 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
373 * Start the lookup of an ipv4 from a hostname
375 int GetIP(const char* name);
378 * Start lookup of a hostname from an ip, but
379 * force a specific protocol to be used for the lookup
380 * for example to perform an ipv6 reverse lookup.
382 int GetNameForce(const char *ip, ForceProtocol fp);
385 * Start lookup of an ipv6 from a hostname
387 int GetIP6(const char *name);
390 * Start lookup of a CNAME from another hostname
392 int GetCName(const char* alias);
395 * Fetch the result string (an ip or host)
396 * and/or an error message to go with it.
398 DNSResult GetResult();
401 * Handle a SocketEngine read event
402 * Inherited from EventHandler
404 void HandleEvent(EventType et, int errornum = 0);
407 * Add a Resolver* to the list of active classes
409 bool AddResolverClass(Resolver* r);
412 * Add a query to the list to be sent
414 DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
417 * The constructor initialises the dns socket,
418 * and clears the request lists.
423 * Re-initialize the DNS subsystem.
432 /** Portable random number generator, generates
433 * its random number from the ircd stats counters,
434 * effective user id, time of day and the rollover
437 unsigned long PRNG();
440 * Turn an in6_addr into a .ip6.arpa domain
442 static void MakeIP6Int(char* query, const in6_addr *ip);
445 * Clean out all dns resolvers owned by a particular
446 * module, to make unloading a module safe if there
447 * are dns requests currently in progress.
449 void CleanResolvers(Module* module);
451 /** Return the cached value of an IP or hostname
452 * @param source An IP or hostname to find in the cache.
453 * @return A pointer to a CachedQuery if the item exists,
456 CachedQuery* GetCache(const std::string &source);
458 /** Delete a cached item from the DNS cache.
459 * @param source An IP or hostname to remove
461 void DelCache(const std::string &source);
463 /** Clear all items from the DNS cache immediately.
467 /** Prune the DNS cache, e.g. remove all expired
468 * items and rehash the cache buckets, but leave
469 * items in the hash which are still valid.