1 /* +------------------------------------+
2 * | Inspire Internet Relay Chat Daemon |
3 * +------------------------------------+
5 * InspIRCd is copyright (C) 2002-2006 ChatSpike-Dev.
7 * <brain@chatspike.net>
8 * <Craig@chatspike.net>
10 * Written by Craig Edwards, Craig McLure, and others.
11 * This program is free but copyrighted software; see
12 * the file COPYING for details.
14 * ---------------------------------------------------
18 dns.h - dns library very very loosely based on
19 firedns, Copyright (C) 2002 Ian Gulliver
21 This program is free software; you can redistribute it and/or modify
22 it under the terms of version 2 of the GNU General Public License as
23 published by the Free Software Foundation.
25 This program is distributed in the hope that it will be useful,
26 but WITHOUT ANY WARRANTY; without even the implied warranty of
27 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
28 GNU General Public License for more details.
30 You should have received a copy of the GNU General Public License
31 along with this program; if not, write to the Free Software
32 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
39 #include "inspircd_config.h"
44 * Result status, used internally
46 typedef std::pair<int,std::string> DNSResult;
49 * Information on a completed lookup, used internally
51 typedef std::pair<unsigned char*, std::string> DNSInfo;
54 * Error types that class Resolver can emit to its error method.
60 RESOLVER_NXDOMAIN = 2,
61 RESOLVER_NOTREADY = 3,
76 * A DNS Resource Record (rr)
81 * A set of requests keyed by request id
83 typedef std::map<int,DNSRequest*> requestlist;
86 * An iterator into a set of requests
88 typedef requestlist::iterator requestlist_iter;
91 * The Resolver class is a high-level abstraction for resolving DNS entries.
92 * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
93 * also be able to do those, transparent of protocols. Module developers must
94 * extend this class via inheritence, and then insert a pointer to their derived
95 * class into the core using Server::AddResolver(). Once you have done this,
96 * the class will be able to receive callbacks. There are two callbacks which
97 * can occur by calling virtual methods, one is a success situation, and the other
100 class Resolver : public Extensible
104 * The input data, either a host or an IP address
108 * True if a forward lookup is being performed, false if otherwise
112 * The DNS erver being used for lookups. If this is an empty string,
113 * the value of ServerConfig::DNSServer is used instead.
117 * The ID allocated to your lookup. This is a pseudo-random number
118 * between 0 and 65535, a value of -1 indicating a failure.
119 * The core uses this to route results to the correct objects.
124 * Initiate DNS lookup. Your class should not attempt to delete or free these
125 * objects, as the core will do this for you. They must always be created upon
126 * the heap using new, as you cannot be sure at what time they will be deleted.
127 * Allocating them on the stack or attempting to delete them yourself could cause
128 * the object to go 'out of scope' and cause a segfault in the core if the result
129 * arrives at a later time.
130 * @param source The IP or hostname to resolve
131 * @param forward Set to true to perform a forward lookup (hostname to ip) or false
132 * to perform a reverse lookup (ip to hostname). Lookups on A records and PTR
133 * records are supported. CNAME and MX are not supported by this resolver.
134 * If InspIRCd is compiled with ipv6 support, lookups on AAAA records are preferred
135 * and supported over A records.
136 * @throw ModuleException This class may throw an instance of ModuleException, in the
137 * event a lookup could not be allocated, or a similar hard error occurs such as
138 * the network being down.
140 Resolver(const std::string &source, bool forward);
142 * The default destructor does nothing.
146 * When your lookup completes, this method will be called.
147 * @param result The resulting DNS lookup, either an IP address or a hostname.
149 virtual void OnLookupComplete(const std::string &result) = 0;
151 * If an error occurs (such as NXDOMAIN, no domain name found) then this method
153 * @param e A ResolverError enum containing the error type which has occured.
154 * @param errormessage The error text of the error that occured.
156 virtual void OnError(ResolverError e, const std::string &errormessage);
158 * Returns the id value of this class. This is primarily used by the core
159 * to determine where in various tables to place a pointer to your class, but it
160 * is safe to call and use this method.
161 * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
162 * from 0 to 65535. If there is an issue and the core cannot send your request,
163 * this method will return -1.
169 * Query and resource record types
173 DNS_QUERY_A = 1, /* 'A' record: an IP address */
174 DNS_QUERY_PTR = 12 /* 'PTR' record: a hostname */
177 /** DNS is a singleton class used by the core to dispatch dns
178 * requests to the dns server, and route incoming dns replies
179 * back to Resolver objects, based upon the request ID. You
180 * should never use this class yourself.
182 class DNS : public Extensible
187 * The maximum value of a dns request id,
188 * 16 bits wide, 0xFFFF.
190 static const int MAX_REQUEST_ID = 0xFFFF;
193 * Requests that are currently 'in flight
195 requestlist requests;
198 * Server address being used currently
200 insp_inaddr myserver;
203 * File descriptor being used to perform queries
205 static int MasterSocket;
208 * A counter used to form part of the pseudo-random id
213 * Currently active Resolver classes
215 Resolver* Classes[MAX_REQUEST_ID];
218 * Build a dns packet payload
220 int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
225 * Fill an rr (resource record) with data from input
227 static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
229 * Fill a header with data from input limited by a length
231 static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
233 * Empty out a header into a data stream ready for transmission "on the wire"
235 static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
237 * Get the master socket fd, used internally
239 static int GetMasterSocket();
242 * Start the lookup of an ip from a hostname
244 int GetIP(const char* name);
247 * Start the lookup of a hostname from an ip
249 int GetName(const insp_inaddr* ip);
252 * Fetch the result string (an ip or host)
253 * and/or an error message to go with it.
255 DNSResult GetResult();
258 * Handle a SocketEngine read event
260 void MarshallReads(int fd);
263 * Add a Resolver* to the list of active classes
265 bool AddResolverClass(Resolver* r);
268 * Add a query to the list to be sent
270 DNSRequest* AddQuery(DNSHeader *header, int &id);
273 * The constructor initialises the dns socket,
274 * and clears the request lists.
283 /** Portable random number generator, generates
284 * its random number from the ircd stats counters,
285 * effective user id, time of day and the rollover
288 unsigned long PRNG();