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.
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,
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 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
165 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
167 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
169 * Used internally to force PTR lookups to use a certain protocol scemantics,
170 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
174 /** Forced to use ipv4 */
176 /** Forced to use ipv6 */
181 * The Resolver class is a high-level abstraction for resolving DNS entries.
182 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
183 * also be able to do those, transparent of protocols. Module developers must
184 * extend this class via inheritence, and then insert a pointer to their derived
185 * class into the core using Server::AddResolver(). Once you have done this,
186 * the class will be able to receive callbacks. There are two callbacks which
187 * can occur by calling virtual methods, one is a success situation, and the other
188 * an error situation.
190 class CoreExport Resolver : public Extensible
196 InspIRCd* ServerInstance;
198 * Pointer to creator module (if any, or NULL)
202 * The input data, either a host or an IP address
206 * True if a forward lookup is being performed, false if otherwise
210 * The DNS erver being used for lookups. If this is an empty string,
211 * the value of ServerConfig::DNSServer is used instead.
215 * The ID allocated to your lookup. This is a pseudo-random number
216 * between 0 and 65535, a value of -1 indicating a failure.
217 * The core uses this to route results to the correct objects.
222 * Cached result, if there is one
227 * Time left before cache expiry
233 * Initiate DNS lookup. Your class should not attempt to delete or free these
234 * objects, as the core will do this for you. They must always be created upon
235 * the heap using new, as you cannot be sure at what time they will be deleted.
236 * Allocating them on the stack or attempting to delete them yourself could cause
237 * the object to go 'out of scope' and cause a segfault in the core if the result
238 * arrives at a later time.
239 * @param source The IP or hostname to resolve
240 * @param qt The query type to perform. If you just want to perform a forward
241 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
242 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
243 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
244 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
245 * is supported. Use one of the QueryType enum values to initiate this type of
246 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
247 * wether InspIRCd is built with ipv6 support.
248 * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
249 * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
250 * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
251 * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
252 * To get around this automatic behaviour, you must use one of the values
253 * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
254 * irrespective of what protocol InspIRCd has been built for.
255 * @param cached The constructor will set this boolean to true or false depending
256 * on whether the DNS lookup you are attempting is cached (and not expired) or not.
257 * If the value is cached, upon return this will be set to true, otherwise it will
258 * be set to false. You should pass this value to InspIRCd::AddResolver(), which
259 * will then influence the behaviour of the method and determine whether a cached
260 * or non-cached result is obtained. The value in this variable is always correct
261 * for the given request when the constructor exits.
262 * @param creator See the note below.
263 * @throw ModuleException This class may throw an instance of ModuleException, in the
264 * event a lookup could not be allocated, or a similar hard error occurs such as
265 * the network being down. This will also be thrown if an invalid IP address is
266 * passed when resolving a 'PTR' record.
268 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
269 * value of creator to point at your Module class. This way if your module is unloaded
270 * whilst lookups are in progress, they can be safely removed and your module will not
273 Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, bool &cached, Module* creator = NULL);
276 * The default destructor does nothing.
281 * When your lookup completes, this method will be called.
282 * @param result The resulting DNS lookup, either an IP address or a hostname.
283 * @param ttl The time-to-live value of the result, in the instance of a cached
284 * result, this is the number of seconds remaining before refresh/expiry.
285 * @param cached True if the result is a cached result, false if it was requested
286 * from the DNS server.
287 * @param resultnum Result number, for records with multiple matching results.
288 * Normally, you will only want to act on this when the result is 0.
290 virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached, int resultnum = 0) = 0;
293 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
295 * @param e A ResolverError enum containing the error type which has occured.
296 * @param errormessage The error text of the error that occured.
298 virtual void OnError(ResolverError e, const std::string &errormessage);
301 * Returns the id value of this class. This is primarily used by the core
302 * to determine where in various tables to place a pointer to your class, but it
303 * is safe to call and use this method.
304 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
305 * from 0 to 65535. If there is an issue and the core cannot send your request,
306 * this method will return -1.
311 * Returns the creator module, or NULL
313 Module* GetCreator();
316 * If the result is a cached result, this triggers the objects
317 * OnLookupComplete. This is done because it is not safe to call
318 * the abstract virtual method from the constructor.
320 void TriggerCachedResult();
323 /** DNS is a singleton class used by the core to dispatch dns
324 * requests to the dns server, and route incoming dns replies
325 * back to Resolver objects, based upon the request ID. You
326 * should never use this class yourself.
328 class CoreExport DNS : public EventHandler
333 * Creator/Owner object
335 InspIRCd* ServerInstance;
338 * The maximum value of a dns request id,
339 * 16 bits wide, 0xFFFF.
341 static const int MAX_REQUEST_ID = 0xFFFF;
344 * A counter used to form part of the pseudo-random id
349 * We have to turn off a few checks on received packets
350 * when people are using 4in6 (e.g. ::ffff:xxxx). This is
351 * a temporary kludge, Please let me know if you know how
357 * Currently cached items
361 /** A timer which ticks every hour to remove expired
362 * items from the DNS cache.
364 class CacheTimer* PruneTimer;
367 * Build a dns packet payload
369 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
374 * Server address being used currently
380 * IPV6 server address
385 * IPV4 server address
390 * Currently active Resolver classes
392 Resolver* Classes[MAX_REQUEST_ID];
395 * Requests that are currently 'in flight'
397 DNSRequest* requests[MAX_REQUEST_ID];
400 * The port number DNS requests are made on,
401 * and replies have as a source-port number.
403 static const int QUERY_PORT = 53;
406 * Fill an rr (resource record) with data from input
408 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
411 * Fill a header with data from input limited by a length
413 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
416 * Empty out a header into a data stream ready for transmission "on the wire"
418 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
421 * Start the lookup of an ipv4 from a hostname
423 int GetIP(const char* name);
426 * Start the lookup of a hostname from an ip,
427 * always using the protocol inspircd is built for,
428 * e.g. use ipv6 reverse lookup when built for ipv6,
429 * or ipv4 lookup when built for ipv4.
431 int GetName(const irc::sockets::insp_inaddr* ip);
434 * Start lookup of a hostname from an ip, but
435 * force a specific protocol to be used for the lookup
436 * for example to perform an ipv6 reverse lookup.
438 int GetNameForce(const char *ip, ForceProtocol fp);
441 * Start lookup of an ipv6 from a hostname
443 int GetIP6(const char *name);
446 * Start lookup of a CNAME from another hostname
448 int GetCName(const char* alias);
451 * Fetch the result string (an ip or host)
452 * and/or an error message to go with it.
453 * @param resultnum Result number to fetch
455 DNSResult GetResult(int resultnum);
458 * Handle a SocketEngine read event
459 * Inherited from EventHandler
461 void HandleEvent(EventType et, int errornum = 0);
464 * Add a Resolver* to the list of active classes
466 bool AddResolverClass(Resolver* r);
469 * Add a query to the list to be sent
471 DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
474 * The constructor initialises the dns socket,
475 * and clears the request lists.
477 DNS(InspIRCd* Instance);
480 * Re-initialize the DNS subsystem.
489 /** Portable random number generator, generates
490 * its random number from the ircd stats counters,
491 * effective user id, time of day and the rollover
494 unsigned long PRNG();
497 * Turn an in6_addr into a .ip6.arpa domain
499 static void MakeIP6Int(char* query, const in6_addr *ip);
502 * Clean out all dns resolvers owned by a particular
503 * module, to make unloading a module safe if there
504 * are dns requests currently in progress.
506 void CleanResolvers(Module* module);
508 /** Return the cached value of an IP or hostname
509 * @param source An IP or hostname to find in the cache.
510 * @return A pointer to a CachedQuery if the item exists,
513 CachedQuery* GetCache(const std::string &source);
515 /** Delete a cached item from the DNS cache.
516 * @param source An IP or hostname to remove
518 void DelCache(const std::string &source);
520 /** Clear all items from the DNS cache immediately.
524 /** Prune the DNS cache, e.g. remove all expired
525 * items and rehash the cache buckets, but leave
526 * items in the hash which are still valid.