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 typedef std::pair<int,std::string> DNSResult;
56 * Information on a completed lookup, used internally
58 typedef std::pair<unsigned char*, std::string> DNSInfo;
61 * Error types that class Resolver can emit to its error method.
67 RESOLVER_NXDOMAIN = 2,
68 RESOLVER_NOTREADY = 3,
71 RESLOVER_FORCEUNLOAD = 6
85 * A DNS Resource Record (rr)
90 * Query and resource record types
94 DNS_QUERY_NONE = 0, /* Uninitialized Query */
95 DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
96 DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
97 DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
98 DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
100 DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */
101 DNS_QUERY_PTR6 = 0xFFFE, /* Force 'PTR' to use IPV6 scemantics */
105 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
106 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
108 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
109 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
113 * Used internally to force PTR lookups to use a certain protocol scemantics,
114 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
118 PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */
119 PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */
123 * The Resolver class is a high-level abstraction for resolving DNS entries.
124 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
125 * also be able to do those, transparent of protocols. Module developers must
126 * extend this class via inheritence, and then insert a pointer to their derived
127 * class into the core using Server::AddResolver(). Once you have done this,
128 * the class will be able to receive callbacks. There are two callbacks which
129 * can occur by calling virtual methods, one is a success situation, and the other
130 * an error situation.
132 class Resolver : public Extensible
138 InspIRCd* ServerInstance;
140 * Pointer to creator module (if any, or NULL)
144 * The input data, either a host or an IP address
148 * True if a forward lookup is being performed, false if otherwise
152 * The DNS erver being used for lookups. If this is an empty string,
153 * the value of ServerConfig::DNSServer is used instead.
157 * The ID allocated to your lookup. This is a pseudo-random number
158 * between 0 and 65535, a value of -1 indicating a failure.
159 * The core uses this to route results to the correct objects.
164 * Initiate DNS lookup. Your class should not attempt to delete or free these
165 * objects, as the core will do this for you. They must always be created upon
166 * the heap using new, as you cannot be sure at what time they will be deleted.
167 * Allocating them on the stack or attempting to delete them yourself could cause
168 * the object to go 'out of scope' and cause a segfault in the core if the result
169 * arrives at a later time.
170 * @param source The IP or hostname to resolve
171 * @param qt The query type to perform. If you just want to perform a forward
172 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
173 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
174 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
175 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
176 * is supported. Use one of the QueryType enum values to initiate this type of
177 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
178 * wether InspIRCd is built with ipv6 support.
179 * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
180 * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
181 * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
182 * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
183 * To get around this automatic behaviour, you must use one of the values
184 * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
185 * irrespective of what protocol InspIRCd has been built for.
186 * @throw ModuleException This class may throw an instance of ModuleException, in the
187 * event a lookup could not be allocated, or a similar hard error occurs such as
188 * the network being down. This will also be thrown if an invalid IP address is
189 * passed when resolving a 'PTR' record.
191 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
192 * value of creator to point at your Module class. This way if your module is unloaded
193 * whilst lookups are in progress, they can be safely removed and your module will not
196 Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, Module* creator = NULL);
199 * The default destructor does nothing.
203 * When your lookup completes, this method will be called.
204 * @param result The resulting DNS lookup, either an IP address or a hostname.
206 virtual void OnLookupComplete(const std::string &result) = 0;
208 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
210 * @param e A ResolverError enum containing the error type which has occured.
211 * @param errormessage The error text of the error that occured.
213 virtual void OnError(ResolverError e, const std::string &errormessage);
215 * Returns the id value of this class. This is primarily used by the core
216 * to determine where in various tables to place a pointer to your class, but it
217 * is safe to call and use this method.
218 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
219 * from 0 to 65535. If there is an issue and the core cannot send your request,
220 * this method will return -1.
225 * Returns the creator module, or NULL
227 Module* GetCreator();
230 /** DNS is a singleton class used by the core to dispatch dns
231 * requests to the dns server, and route incoming dns replies
232 * back to Resolver objects, based upon the request ID. You
233 * should never use this class yourself.
235 class DNS : public EventHandler
239 InspIRCd* ServerInstance;
242 * The maximum value of a dns request id,
243 * 16 bits wide, 0xFFFF.
245 static const int MAX_REQUEST_ID = 0xFFFF;
248 * Server address being used currently
250 insp_inaddr myserver;
253 * A counter used to form part of the pseudo-random id
258 * We have to turn off a few checks on received packets
259 * when people are using 4in6 (e.g. ::ffff:xxxx). This is
260 * a temporary kludge, Please let me know if you know how
266 * Build a dns packet payload
268 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
272 * Currently active Resolver classes
274 Resolver* Classes[MAX_REQUEST_ID];
276 * Requests that are currently 'in flight'
278 DNSRequest* requests[MAX_REQUEST_ID];
280 * The port number DNS requests are made on,
281 * and replies have as a source-port number.
283 static const int QUERY_PORT = 53;
286 * Fill an rr (resource record) with data from input
288 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
290 * Fill a header with data from input limited by a length
292 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
294 * Empty out a header into a data stream ready for transmission "on the wire"
296 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
298 * Start the lookup of an ipv4 from a hostname
300 int GetIP(const char* name);
303 * Start the lookup of a hostname from an ip,
304 * always using the protocol inspircd is built for,
305 * e.g. use ipv6 reverse lookup when built for ipv6,
306 * or ipv4 lookup when built for ipv4.
308 int GetName(const insp_inaddr* ip);
311 * Start lookup of a hostname from an ip, but
312 * force a specific protocol to be used for the lookup
313 * for example to perform an ipv6 reverse lookup.
315 int GetNameForce(const char *ip, ForceProtocol fp);
318 * Start lookup of an ipv6 from a hostname
320 int GetIP6(const char *name);
323 * Start lookup of a CNAME from another hostname
325 int GetCName(const char* alias);
328 * Fetch the result string (an ip or host)
329 * and/or an error message to go with it.
331 DNSResult GetResult();
334 * Handle a SocketEngine read event
335 * Inherited from EventHandler
337 void HandleEvent(EventType et, int errornum = 0);
340 * Add a Resolver* to the list of active classes
342 bool AddResolverClass(Resolver* r);
345 * Add a query to the list to be sent
347 DNSRequest* AddQuery(DNSHeader *header, int &id);
350 * The constructor initialises the dns socket,
351 * and clears the request lists.
353 DNS(InspIRCd* Instance);
360 /** Portable random number generator, generates
361 * its random number from the ircd stats counters,
362 * effective user id, time of day and the rollover
365 unsigned long PRNG();
368 * Turn an in6_addr into a .ip6.arpa domain
370 static void MakeIP6Int(char* query, const in6_addr *ip);
373 * Clean out all dns resolvers owned by a particular
374 * module, to make unloading a module safe if there
375 * are dns requests currently in progress.
377 void CleanResolvers(Module* module);