1 /* +------------------------------------+
2 * | Inspire Internet Relay Chat Daemon |
3 * +------------------------------------+
5 * InspIRCd: (C) 2002-2008 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
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.
107 typedef nspace::hash_map<irc::string, CachedQuery, nspace::hash<irc::string> > dnscache;
109 typedef nspace::hash_map<irc::string, CachedQuery, nspace::hash_compare<irc::string> > dnscache;
113 * Error types that class Resolver can emit to its error method.
117 RESOLVER_NOERROR = 0,
119 RESOLVER_NXDOMAIN = 2,
120 RESOLVER_NOTREADY = 3,
122 RESOLVER_TIMEOUT = 5,
123 RESLOVER_FORCEUNLOAD = 6
132 * A DNS packet header
137 * A DNS Resource Record (rr)
139 struct ResourceRecord;
142 * Query and resource record types
146 DNS_QUERY_NONE = 0, /* Uninitialized Query */
147 DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
148 DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
149 DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
150 DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
152 DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */
153 DNS_QUERY_PTR6 = 0xFFFE /* Force 'PTR' to use IPV6 scemantics */
157 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
159 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
161 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
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 PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */
169 PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */
173 * The Resolver class is a high-level abstraction for resolving DNS entries.
174 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
175 * also be able to do those, transparent of protocols. Module developers must
176 * extend this class via inheritence, and then insert a pointer to their derived
177 * class into the core using Server::AddResolver(). Once you have done this,
178 * the class will be able to receive callbacks. There are two callbacks which
179 * can occur by calling virtual methods, one is a success situation, and the other
180 * an error situation.
182 class CoreExport Resolver : public Extensible
188 InspIRCd* ServerInstance;
190 * Pointer to creator module (if any, or NULL)
194 * The input data, either a host or an IP address
198 * True if a forward lookup is being performed, false if otherwise
202 * The DNS erver being used for lookups. If this is an empty string,
203 * the value of ServerConfig::DNSServer is used instead.
207 * The ID allocated to your lookup. This is a pseudo-random number
208 * between 0 and 65535, a value of -1 indicating a failure.
209 * The core uses this to route results to the correct objects.
214 * Cached result, if there is one
219 * Time left before cache expiry
224 * Initiate DNS lookup. Your class should not attempt to delete or free these
225 * objects, as the core will do this for you. They must always be created upon
226 * the heap using new, as you cannot be sure at what time they will be deleted.
227 * Allocating them on the stack or attempting to delete them yourself could cause
228 * the object to go 'out of scope' and cause a segfault in the core if the result
229 * arrives at a later time.
230 * @param source The IP or hostname to resolve
231 * @param qt The query type to perform. If you just want to perform a forward
232 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
233 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
234 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
235 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
236 * is supported. Use one of the QueryType enum values to initiate this type of
237 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
238 * wether InspIRCd is built with ipv6 support.
239 * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
240 * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
241 * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
242 * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
243 * To get around this automatic behaviour, you must use one of the values
244 * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
245 * irrespective of what protocol InspIRCd has been built for.
246 * @param cached The constructor will set this boolean to true or false depending
247 * on whether the DNS lookup you are attempting is cached (and not expired) or not.
248 * If the value is cached, upon return this will be set to true, otherwise it will
249 * be set to false. You should pass this value to InspIRCd::AddResolver(), which
250 * will then influence the behaviour of the method and determine whether a cached
251 * or non-cached result is obtained. The value in this variable is always correct
252 * for the given request when the constructor exits.
253 * @param creator See the note below.
254 * @throw ModuleException This class may throw an instance of ModuleException, in the
255 * event a lookup could not be allocated, or a similar hard error occurs such as
256 * the network being down. This will also be thrown if an invalid IP address is
257 * passed when resolving a 'PTR' record.
259 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
260 * value of creator to point at your Module class. This way if your module is unloaded
261 * whilst lookups are in progress, they can be safely removed and your module will not
264 Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, bool &cached, Module* creator = NULL);
267 * The default destructor does nothing.
271 * When your lookup completes, this method will be called.
272 * @param result The resulting DNS lookup, either an IP address or a hostname.
273 * @param ttl The time-to-live value of the result, in the instance of a cached
274 * result, this is the number of seconds remaining before refresh/expiry.
275 * @param cached True if the result is a cached result, false if it was requested
276 * from the DNS server.
277 * @param resultnum Result number, for records with multiple matching results.
278 * Normally, you will only want to act on this when the result is 0.
280 virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached, int resultnum = 0) = 0;
282 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
284 * @param e A ResolverError enum containing the error type which has occured.
285 * @param errormessage The error text of the error that occured.
287 virtual void OnError(ResolverError e, const std::string &errormessage);
289 * Returns the id value of this class. This is primarily used by the core
290 * to determine where in various tables to place a pointer to your class, but it
291 * is safe to call and use this method.
292 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
293 * from 0 to 65535. If there is an issue and the core cannot send your request,
294 * this method will return -1.
298 * Returns the creator module, or NULL
300 Module* GetCreator();
302 * If the result is a cached result, this triggers the objects
303 * OnLookupComplete. This is done because it is not safe to call
304 * the abstract virtual method from the constructor.
306 void TriggerCachedResult();
309 /** DNS is a singleton class used by the core to dispatch dns
310 * requests to the dns server, and route incoming dns replies
311 * back to Resolver objects, based upon the request ID. You
312 * should never use this class yourself.
314 class CoreExport DNS : public EventHandler
319 * Creator/Owner object
321 InspIRCd* ServerInstance;
324 * The maximum value of a dns request id,
325 * 16 bits wide, 0xFFFF.
327 static const int MAX_REQUEST_ID = 0xFFFF;
330 * A counter used to form part of the pseudo-random id
335 * We have to turn off a few checks on received packets
336 * when people are using 4in6 (e.g. ::ffff:xxxx). This is
337 * a temporary kludge, Please let me know if you know how
343 * Currently cached items
347 /** A timer which ticks every hour to remove expired
348 * items from the DNS cache.
350 class CacheTimer* PruneTimer;
353 * Build a dns packet payload
355 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
360 * Server address being used currently
369 * Currently active Resolver classes
371 Resolver* Classes[MAX_REQUEST_ID];
374 * Requests that are currently 'in flight'
376 DNSRequest* requests[MAX_REQUEST_ID];
379 * The port number DNS requests are made on,
380 * and replies have as a source-port number.
382 static const int QUERY_PORT = 53;
385 * Fill an rr (resource record) with data from input
387 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
390 * Fill a header with data from input limited by a length
392 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
395 * Empty out a header into a data stream ready for transmission "on the wire"
397 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
400 * Start the lookup of an ipv4 from a hostname
402 int GetIP(const char* name);
405 * Start the lookup of a hostname from an ip,
406 * always using the protocol inspircd is built for,
407 * e.g. use ipv6 reverse lookup when built for ipv6,
408 * or ipv4 lookup when built for ipv4.
410 int GetName(const irc::sockets::insp_inaddr* ip);
413 * Start lookup of a hostname from an ip, but
414 * force a specific protocol to be used for the lookup
415 * for example to perform an ipv6 reverse lookup.
417 int GetNameForce(const char *ip, ForceProtocol fp);
420 * Start lookup of an ipv6 from a hostname
422 int GetIP6(const char *name);
425 * Start lookup of a CNAME from another hostname
427 int GetCName(const char* alias);
430 * Fetch the result string (an ip or host)
431 * and/or an error message to go with it.
432 * @param resultnum Result number to fetch
434 DNSResult GetResult(int resultnum);
437 * Handle a SocketEngine read event
438 * Inherited from EventHandler
440 void HandleEvent(EventType et, int errornum = 0);
443 * Add a Resolver* to the list of active classes
445 bool AddResolverClass(Resolver* r);
448 * Add a query to the list to be sent
450 DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
453 * The constructor initialises the dns socket,
454 * and clears the request lists.
456 DNS(InspIRCd* Instance);
459 * Re-initialize the DNS subsystem.
468 /** Portable random number generator, generates
469 * its random number from the ircd stats counters,
470 * effective user id, time of day and the rollover
473 unsigned long PRNG();
476 * Turn an in6_addr into a .ip6.arpa domain
478 static void MakeIP6Int(char* query, const in6_addr *ip);
481 * Clean out all dns resolvers owned by a particular
482 * module, to make unloading a module safe if there
483 * are dns requests currently in progress.
485 void CleanResolvers(Module* module);
487 /** Return the cached value of an IP or hostname
488 * @param source An IP or hostname to find in the cache.
489 * @return A pointer to a CachedQuery if the item exists,
492 CachedQuery* GetCache(const std::string &source);
494 /** Delete a cached item from the DNS cache.
495 * @param source An IP or hostname to remove
497 void DelCache(const std::string &source);
499 /** Clear all items from the DNS cache immediately.
503 /** Prune the DNS cache, e.g. remove all expired
504 * items and rehash the cache buckets, but leave
505 * items in the hash which are still valid.