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 * A set of requests keyed by request id
92 typedef std::map<int,DNSRequest*> requestlist;
95 * An iterator into a set of requests
97 typedef requestlist::iterator requestlist_iter;
100 * Query and resource record types
104 DNS_QUERY_NONE = 0, /* Uninitialized Query */
105 DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
106 DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
107 DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
108 DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
110 DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */
111 DNS_QUERY_PTR6 = 0xFFFE, /* Force 'PTR' to use IPV6 scemantics */
115 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
116 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
118 const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
119 const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
123 * Used internally to force PTR lookups to use a certain protocol scemantics,
124 * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
128 PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */
129 PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */
133 * The Resolver class is a high-level abstraction for resolving DNS entries.
134 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
135 * also be able to do those, transparent of protocols. Module developers must
136 * extend this class via inheritence, and then insert a pointer to their derived
137 * class into the core using Server::AddResolver(). Once you have done this,
138 * the class will be able to receive callbacks. There are two callbacks which
139 * can occur by calling virtual methods, one is a success situation, and the other
140 * an error situation.
142 class Resolver : public Extensible
148 InspIRCd* ServerInstance;
150 * Pointer to creator module (if any, or NULL)
154 * The input data, either a host or an IP address
158 * True if a forward lookup is being performed, false if otherwise
162 * The DNS erver being used for lookups. If this is an empty string,
163 * the value of ServerConfig::DNSServer is used instead.
167 * The ID allocated to your lookup. This is a pseudo-random number
168 * between 0 and 65535, a value of -1 indicating a failure.
169 * The core uses this to route results to the correct objects.
174 * Initiate DNS lookup. Your class should not attempt to delete or free these
175 * objects, as the core will do this for you. They must always be created upon
176 * the heap using new, as you cannot be sure at what time they will be deleted.
177 * Allocating them on the stack or attempting to delete them yourself could cause
178 * the object to go 'out of scope' and cause a segfault in the core if the result
179 * arrives at a later time.
180 * @param source The IP or hostname to resolve
181 * @param qt The query type to perform. If you just want to perform a forward
182 * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
183 * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
184 * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
185 * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
186 * is supported. Use one of the QueryType enum values to initiate this type of
187 * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
188 * wether InspIRCd is built with ipv6 support.
189 * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
190 * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
191 * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
192 * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
193 * To get around this automatic behaviour, you must use one of the values
194 * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
195 * irrespective of what protocol InspIRCd has been built for.
196 * @throw ModuleException This class may throw an instance of ModuleException, in the
197 * event a lookup could not be allocated, or a similar hard error occurs such as
198 * the network being down. This will also be thrown if an invalid IP address is
199 * passed when resolving a 'PTR' record.
201 * NOTE: If you are instantiating your DNS lookup from a module, you should set the
202 * value of creator to point at your Module class. This way if your module is unloaded
203 * whilst lookups are in progress, they can be safely removed and your module will not
206 Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, Module* creator = NULL);
209 * The default destructor does nothing.
213 * When your lookup completes, this method will be called.
214 * @param result The resulting DNS lookup, either an IP address or a hostname.
216 virtual void OnLookupComplete(const std::string &result) = 0;
218 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
220 * @param e A ResolverError enum containing the error type which has occured.
221 * @param errormessage The error text of the error that occured.
223 virtual void OnError(ResolverError e, const std::string &errormessage);
225 * Returns the id value of this class. This is primarily used by the core
226 * to determine where in various tables to place a pointer to your class, but it
227 * is safe to call and use this method.
228 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
229 * from 0 to 65535. If there is an issue and the core cannot send your request,
230 * this method will return -1.
235 * Returns the creator module, or NULL
237 Module* GetCreator();
240 /** DNS is a singleton class used by the core to dispatch dns
241 * requests to the dns server, and route incoming dns replies
242 * back to Resolver objects, based upon the request ID. You
243 * should never use this class yourself.
245 class DNS : public EventHandler
249 InspIRCd* ServerInstance;
252 * The maximum value of a dns request id,
253 * 16 bits wide, 0xFFFF.
255 static const int MAX_REQUEST_ID = 0xFFFF;
258 * Requests that are currently 'in flight'
260 requestlist requests;
263 * Server address being used currently
265 insp_inaddr myserver;
268 * A counter used to form part of the pseudo-random id
273 * We have to turn off a few checks on received packets
274 * when people are using 4in6 (e.g. ::ffff:xxxx). This is
275 * a temporary kludge, Please let me know if you know how
281 * Build a dns packet payload
283 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
287 * Currently active Resolver classes
289 Resolver* Classes[MAX_REQUEST_ID];
291 * The port number DNS requests are made on,
292 * and replies have as a source-port number.
294 static const int QUERY_PORT = 53;
297 * Fill an rr (resource record) with data from input
299 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
301 * Fill a header with data from input limited by a length
303 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
305 * Empty out a header into a data stream ready for transmission "on the wire"
307 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
309 * Start the lookup of an ipv4 from a hostname
311 int GetIP(const char* name);
314 * Start the lookup of a hostname from an ip,
315 * always using the protocol inspircd is built for,
316 * e.g. use ipv6 reverse lookup when built for ipv6,
317 * or ipv4 lookup when built for ipv4.
319 int GetName(const insp_inaddr* ip);
322 * Start lookup of a hostname from an ip, but
323 * force a specific protocol to be used for the lookup
324 * for example to perform an ipv6 reverse lookup.
326 int GetNameForce(const char *ip, ForceProtocol fp);
329 * Start lookup of an ipv6 from a hostname
331 int GetIP6(const char *name);
334 * Start lookup of a CNAME from another hostname
336 int GetCName(const char* alias);
339 * Fetch the result string (an ip or host)
340 * and/or an error message to go with it.
342 DNSResult GetResult();
345 * Handle a SocketEngine read event
346 * Inherited from EventHandler
348 void HandleEvent(EventType et, int errornum = 0);
351 * Add a Resolver* to the list of active classes
353 bool AddResolverClass(Resolver* r);
356 * Add a query to the list to be sent
358 DNSRequest* AddQuery(DNSHeader *header, int &id);
361 * The constructor initialises the dns socket,
362 * and clears the request lists.
364 DNS(InspIRCd* Instance);
371 /** Portable random number generator, generates
372 * its random number from the ircd stats counters,
373 * effective user id, time of day and the rollover
376 unsigned long PRNG();
379 * Turn an in6_addr into a .ip6.arpa domain
381 static void MakeIP6Int(char* query, const in6_addr *ip);
384 * Clean out all dns resolvers owned by a particular
385 * module, to make unloading a module safe if there
386 * are dns requests currently in progress.
388 void CleanResolvers(Module* module);