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/>.
22 dns.h - dns library very very loosely based on
23 firedns, Copyright (C) 2002 Ian Gulliver
25 This program is free software; you can redistribute it and/or modify
26 it under the terms of version 2 of the GNU General Public License as
27 published by the Free Software Foundation.
29 This program is distributed in the hope that it will be useful,
30 but WITHOUT ANY WARRANTY; without even the implied warranty of
31 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
32 GNU General Public License for more details.
34 You should have received a copy of the GNU General Public License
35 along with this program; if not, write to the Free Software
36 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
46 * Result status, used internally
48 class CoreExport DNSResult
54 /** Result body, a hostname or IP address
57 /** Time-to-live value of the result
60 /** The original request, a hostname or IP address
64 /** Build a DNS result.
65 * @param i The request ID
66 * @param res The request result, a hostname or IP
67 * @param timetolive The request time-to-live
68 * @param orig The original request, a hostname or IP
70 DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig) : id(i), result(res), ttl(timetolive), original(orig) { }
74 * Information on a completed lookup, used internally
76 typedef std::pair<unsigned char*, std::string> DNSInfo;
78 /** Cached item stored in the query cache.
80 class CoreExport CachedQuery
83 /** The cached result data, an IP or hostname
86 /** The time when the item is due to expire
90 /** Build a cached query
91 * @param res The result data, an IP or hostname
92 * @param ttl The time-to-live value of the query result
94 CachedQuery(const std::string &res, unsigned int ttl);
96 /** Returns the number of seconds remaining before this
97 * cache item has expired and should be removed.
99 int CalcTTLRemaining();
102 /** DNS cache information. Holds IPs mapped to hostnames, and hostnames mapped to IPs.
104 typedef std::tr1::unordered_map<irc::string, CachedQuery, irc::hash> dnscache;
107 * Error types that class Resolver can emit to its error method.
111 RESOLVER_NOERROR = 0,
113 RESOLVER_NXDOMAIN = 2,
115 RESOLVER_TIMEOUT = 4,
116 RESOLVER_FORCEUNLOAD = 5
120 * Query and resource record types
124 /** Uninitialized Query */
126 /** 'A' record: an ipv4 address */
128 /** 'CNAME' record: An alias */
130 /** 'PTR' record: a hostname */
132 /** 'AAAA' record: an ipv6 address */
135 /** Force 'PTR' to use IPV4 scemantics */
136 DNS_QUERY_PTR4 = 0xFFFD,
137 /** Force 'PTR' to use IPV6 scemantics */
138 DNS_QUERY_PTR6 = 0xFFFE
142 * Used internally to force PTR lookups to use a certain protocol scemantics,
143 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
147 /** Forced to use ipv4 */
149 /** Forced to use ipv6 */
154 * The Resolver class is a high-level abstraction for resolving DNS entries.
155 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
156 * also be able to do those, transparent of protocols. Module developers must
157 * extend this class via inheritence, and then insert a pointer to their derived
158 * class into the core using Server::AddResolver(). Once you have done this,
159 * the class will be able to receive callbacks. There are two callbacks which
160 * can occur by calling virtual methods, one is a success situation, and the other
161 * an error situation.
163 class CoreExport Resolver
167 * Pointer to creator module (if any, or NULL)
171 * The input data, either a host or an IP address
175 * True if a forward lookup is being performed, false if otherwise
179 * The DNS erver being used for lookups. If this is an empty string,
180 * the value of ServerConfig::DNSServer is used instead.
184 * The ID allocated to your lookup. This is a pseudo-random number
185 * between 0 and 65535, a value of -1 indicating a failure.
186 * The core uses this to route results to the correct objects.
191 * Cached result, if there is one
196 * Time left before cache expiry
202 * Initiate DNS lookup. Your class should not attempt to delete or free these
203 * objects, as the core will do this for you. They must always be created upon
204 * the heap using new, as you cannot be sure at what time they will be deleted.
205 * Allocating them on the stack or attempting to delete them yourself could cause
206 * the object to go 'out of scope' and cause a segfault in the core if the result
207 * arrives at a later time.
208 * @param source The IP or hostname to resolve
209 * @param qt The query type to perform. Resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
210 * is supported. Use one of the QueryType enum values to initiate this type of
211 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
212 * wether InspIRCd is built with ipv6 support.
213 * To look up reverse records, specify one of DNS_QUERY_PTR4 or DNS_QUERY_PTR6 depending
214 * on the type of address you are looking up.
215 * @param cached The constructor will set this boolean to true or false depending
216 * on whether the DNS lookup you are attempting is cached (and not expired) or not.
217 * If the value is cached, upon return this will be set to true, otherwise it will
218 * be set to false. You should pass this value to InspIRCd::AddResolver(), which
219 * will then influence the behaviour of the method and determine whether a cached
220 * or non-cached result is obtained. The value in this variable is always correct
221 * for the given request when the constructor exits.
222 * @param creator See the note below.
223 * @throw ModuleException This class may throw an instance of ModuleException, in the
224 * event a lookup could not be allocated, or a similar hard error occurs such as
225 * the network being down. This will also be thrown if an invalid IP address is
226 * passed when resolving a 'PTR' record.
228 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
229 * value of creator to point at your Module class. This way if your module is unloaded
230 * whilst lookups are in progress, they can be safely removed and your module will not
233 Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator);
236 * The default destructor does nothing.
241 * When your lookup completes, this method will be called.
242 * @param result The resulting DNS lookup, either an IP address or a hostname.
243 * @param ttl The time-to-live value of the result, in the instance of a cached
244 * result, this is the number of seconds remaining before refresh/expiry.
245 * @param cached True if the result is a cached result, false if it was requested
246 * from the DNS server.
248 virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached) = 0;
251 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
253 * @param e A ResolverError enum containing the error type which has occured.
254 * @param errormessage The error text of the error that occured.
256 virtual void OnError(ResolverError e, const std::string &errormessage);
259 * Returns the id value of this class. This is primarily used by the core
260 * to determine where in various tables to place a pointer to your class, but it
261 * is safe to call and use this method.
262 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
263 * from 0 to 65535. If there is an issue and the core cannot send your request,
264 * this method will return -1.
269 * Returns the creator module, or NULL
271 Module* GetCreator();
274 * If the result is a cached result, this triggers the objects
275 * OnLookupComplete. This is done because it is not safe to call
276 * the abstract virtual method from the constructor.
278 void TriggerCachedResult();
281 /** DNS is a singleton class used by the core to dispatch dns
282 * requests to the dns server, and route incoming dns replies
283 * back to Resolver objects, based upon the request ID. You
284 * should never use this class yourself.
286 class CoreExport DNS : public EventHandler
291 * The maximum value of a dns request id,
292 * 16 bits wide, 0xFFFF.
294 static const int MAX_REQUEST_ID = 0xFFFF;
297 * Currently cached items
301 /** A timer which ticks every hour to remove expired
302 * items from the DNS cache.
304 class CacheTimer* PruneTimer;
307 * Build a dns packet payload
309 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
313 irc::sockets::sockaddrs myserver;
316 * Currently active Resolver classes
318 Resolver* Classes[MAX_REQUEST_ID];
321 * Requests that are currently 'in flight'
323 DNSRequest* requests[MAX_REQUEST_ID];
326 * The port number DNS requests are made on,
327 * and replies have as a source-port number.
329 static const int QUERY_PORT = 53;
332 * Fill an rr (resource record) with data from input
334 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
337 * Fill a header with data from input limited by a length
339 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
342 * Empty out a header into a data stream ready for transmission "on the wire"
344 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
347 * Start the lookup of an ipv4 from a hostname
349 int GetIP(const char* name);
352 * Start lookup of a hostname from an ip, but
353 * force a specific protocol to be used for the lookup
354 * for example to perform an ipv6 reverse lookup.
356 int GetNameForce(const char *ip, ForceProtocol fp);
359 * Start lookup of an ipv6 from a hostname
361 int GetIP6(const char *name);
364 * Start lookup of a CNAME from another hostname
366 int GetCName(const char* alias);
369 * Fetch the result string (an ip or host)
370 * and/or an error message to go with it.
372 DNSResult GetResult();
375 * Handle a SocketEngine read event
376 * Inherited from EventHandler
378 void HandleEvent(EventType et, int errornum = 0);
381 * Add a Resolver* to the list of active classes
383 bool AddResolverClass(Resolver* r);
386 * Add a query to the list to be sent
388 DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
391 * The constructor initialises the dns socket,
392 * and clears the request lists.
397 * Re-initialize the DNS subsystem.
407 * Turn an in6_addr into a .ip6.arpa domain
409 static void MakeIP6Int(char* query, const in6_addr *ip);
412 * Clean out all dns resolvers owned by a particular
413 * module, to make unloading a module safe if there
414 * are dns requests currently in progress.
416 void CleanResolvers(Module* module);
418 /** Return the cached value of an IP or hostname
419 * @param source An IP or hostname to find in the cache.
420 * @return A pointer to a CachedQuery if the item exists,
423 CachedQuery* GetCache(const std::string &source);
425 /** Delete a cached item from the DNS cache.
426 * @param source An IP or hostname to remove
428 void DelCache(const std::string &source);
430 /** Clear all items from the DNS cache immediately.
434 /** Prune the DNS cache, e.g. remove all expired
435 * items and rehash the cache buckets, but leave
436 * items in the hash which are still valid.