1 /* +------------------------------------+
2 * | Inspire Internet Relay Chat Daemon |
3 * +------------------------------------+
5 * InspIRCd: (C) 2002-2007 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
36 #include "inspircd_config.h"
38 #include "socketengine.h"
42 using irc::sockets::insp_aton;
43 using irc::sockets::insp_ntoa;
44 using irc::sockets::insp_sockaddr;
45 using irc::sockets::insp_inaddr;
51 * Result status, used internally
53 class DNSResult : public classbase
60 DNSResult(int i, const std::string &res, unsigned long timetolive) : id(i), result(res), ttl(timetolive) { }
64 * Information on a completed lookup, used internally
66 typedef std::pair<unsigned char*, std::string> DNSInfo;
69 * Error types that class Resolver can emit to its error method.
75 RESOLVER_NXDOMAIN = 2,
76 RESOLVER_NOTREADY = 3,
79 RESLOVER_FORCEUNLOAD = 6
93 * A DNS Resource Record (rr)
98 * Query and resource record types
102 DNS_QUERY_NONE = 0, /* Uninitialized Query */
103 DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
104 DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
105 DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
106 DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
108 DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */
109 DNS_QUERY_PTR6 = 0xFFFE, /* Force 'PTR' to use IPV6 scemantics */
113 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
114 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
116 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
117 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
121 * Used internally to force PTR lookups to use a certain protocol scemantics,
122 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
126 PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */
127 PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */
131 * The Resolver class is a high-level abstraction for resolving DNS entries.
132 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
133 * also be able to do those, transparent of protocols. Module developers must
134 * extend this class via inheritence, and then insert a pointer to their derived
135 * class into the core using Server::AddResolver(). Once you have done this,
136 * the class will be able to receive callbacks. There are two callbacks which
137 * can occur by calling virtual methods, one is a success situation, and the other
138 * an error situation.
140 class Resolver : public Extensible
146 InspIRCd* ServerInstance;
148 * Pointer to creator module (if any, or NULL)
152 * The input data, either a host or an IP address
156 * True if a forward lookup is being performed, false if otherwise
160 * The DNS erver being used for lookups. If this is an empty string,
161 * the value of ServerConfig::DNSServer is used instead.
165 * The ID allocated to your lookup. This is a pseudo-random number
166 * between 0 and 65535, a value of -1 indicating a failure.
167 * The core uses this to route results to the correct objects.
172 * Initiate DNS lookup. Your class should not attempt to delete or free these
173 * objects, as the core will do this for you. They must always be created upon
174 * the heap using new, as you cannot be sure at what time they will be deleted.
175 * Allocating them on the stack or attempting to delete them yourself could cause
176 * the object to go 'out of scope' and cause a segfault in the core if the result
177 * arrives at a later time.
178 * @param source The IP or hostname to resolve
179 * @param qt The query type to perform. If you just want to perform a forward
180 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
181 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
182 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
183 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
184 * is supported. Use one of the QueryType enum values to initiate this type of
185 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
186 * wether InspIRCd is built with ipv6 support.
187 * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
188 * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
189 * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
190 * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
191 * To get around this automatic behaviour, you must use one of the values
192 * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
193 * irrespective of what protocol InspIRCd has been built for.
194 * @throw ModuleException This class may throw an instance of ModuleException, in the
195 * event a lookup could not be allocated, or a similar hard error occurs such as
196 * the network being down. This will also be thrown if an invalid IP address is
197 * passed when resolving a 'PTR' record.
199 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
200 * value of creator to point at your Module class. This way if your module is unloaded
201 * whilst lookups are in progress, they can be safely removed and your module will not
204 Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, Module* creator = NULL);
207 * The default destructor does nothing.
211 * When your lookup completes, this method will be called.
212 * @param result The resulting DNS lookup, either an IP address or a hostname.
214 virtual void OnLookupComplete(const std::string &result, unsigned int ttl) = 0;
216 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
218 * @param e A ResolverError enum containing the error type which has occured.
219 * @param errormessage The error text of the error that occured.
221 virtual void OnError(ResolverError e, const std::string &errormessage);
223 * Returns the id value of this class. This is primarily used by the core
224 * to determine where in various tables to place a pointer to your class, but it
225 * is safe to call and use this method.
226 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
227 * from 0 to 65535. If there is an issue and the core cannot send your request,
228 * this method will return -1.
233 * Returns the creator module, or NULL
235 Module* GetCreator();
238 /** DNS is a singleton class used by the core to dispatch dns
239 * requests to the dns server, and route incoming dns replies
240 * back to Resolver objects, based upon the request ID. You
241 * should never use this class yourself.
243 class DNS : public EventHandler
247 InspIRCd* ServerInstance;
250 * The maximum value of a dns request id,
251 * 16 bits wide, 0xFFFF.
253 static const int MAX_REQUEST_ID = 0xFFFF;
256 * Server address being used currently
258 insp_inaddr myserver;
261 * A counter used to form part of the pseudo-random id
266 * We have to turn off a few checks on received packets
267 * when people are using 4in6 (e.g. ::ffff:xxxx). This is
268 * a temporary kludge, Please let me know if you know how
274 * Build a dns packet payload
276 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
280 * Currently active Resolver classes
282 Resolver* Classes[MAX_REQUEST_ID];
284 * Requests that are currently 'in flight'
286 DNSRequest* requests[MAX_REQUEST_ID];
288 * The port number DNS requests are made on,
289 * and replies have as a source-port number.
291 static const int QUERY_PORT = 53;
294 * Fill an rr (resource record) with data from input
296 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
298 * Fill a header with data from input limited by a length
300 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
302 * Empty out a header into a data stream ready for transmission "on the wire"
304 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
306 * Start the lookup of an ipv4 from a hostname
308 int GetIP(const char* name);
311 * Start the lookup of a hostname from an ip,
312 * always using the protocol inspircd is built for,
313 * e.g. use ipv6 reverse lookup when built for ipv6,
314 * or ipv4 lookup when built for ipv4.
316 int GetName(const insp_inaddr* ip);
319 * Start lookup of a hostname from an ip, but
320 * force a specific protocol to be used for the lookup
321 * for example to perform an ipv6 reverse lookup.
323 int GetNameForce(const char *ip, ForceProtocol fp);
326 * Start lookup of an ipv6 from a hostname
328 int GetIP6(const char *name);
331 * Start lookup of a CNAME from another hostname
333 int GetCName(const char* alias);
336 * Fetch the result string (an ip or host)
337 * and/or an error message to go with it.
339 DNSResult GetResult();
342 * Handle a SocketEngine read event
343 * Inherited from EventHandler
345 void HandleEvent(EventType et, int errornum = 0);
348 * Add a Resolver* to the list of active classes
350 bool AddResolverClass(Resolver* r);
353 * Add a query to the list to be sent
355 DNSRequest* AddQuery(DNSHeader *header, int &id);
358 * The constructor initialises the dns socket,
359 * and clears the request lists.
361 DNS(InspIRCd* Instance);
364 * Re-initialize the DNS subsystem.
373 /** Portable random number generator, generates
374 * its random number from the ircd stats counters,
375 * effective user id, time of day and the rollover
378 unsigned long PRNG();
381 * Turn an in6_addr into a .ip6.arpa domain
383 static void MakeIP6Int(char* query, const in6_addr *ip);
386 * Clean out all dns resolvers owned by a particular
387 * module, to make unloading a module safe if there
388 * are dns requests currently in progress.
390 void CleanResolvers(Module* module);