1 /* +------------------------------------+
\r * | Inspire Internet Relay Chat Daemon |
\r * +------------------------------------+
\r *
\r * InspIRCd: (C) 2002-2007 InspIRCd Development Team
\r * See: http://www.inspircd.org/wiki/index.php/Credits
\r *
\r * This program is free but copyrighted software; see
\r * the file COPYING for details.
\r *
\r * ---------------------------------------------------
\r */
\r\r/*
\rdns.h - dns library very very loosely based on
\rfiredns, Copyright (C) 2002 Ian Gulliver
\r\rThis program is free software; you can redistribute it and/or modify
\rit under the terms of version 2 of the GNU General Public License as
\rpublished by the Free Software Foundation.
\r\rThis program is distributed in the hope that it will be useful,
\rbut WITHOUT ANY WARRANTY; without even the implied warranty of
\rMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
\rGNU General Public License for more details.
\r\rYou should have received a copy of the GNU General Public License
\ralong with this program; if not, write to the Free Software
\rFoundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
\r*/
\r\r#ifndef _DNS_H
\r#define _DNS_H
\r\r#include <string>
\r#include "inspircd_config.h"
\r#include "base.h"
\r#include "socketengine.h"
\r#include "socket.h"
\r#include "hash_map.h"
\r#include "hashcomp.h"
\r\rusing namespace std;
\rusing irc::sockets::insp_aton;
\rusing irc::sockets::insp_ntoa;
\rusing irc::sockets::insp_sockaddr;
\rusing irc::sockets::insp_inaddr;
\r\rclass InspIRCd;
\rclass Module;
\r\r/**
\r * Result status, used internally
\r */
\rclass CoreExport DNSResult : public classbase
\r{
\r public:
\r /** Result ID
\r */
\r int id;
\r /** Result body, a hostname or IP address
\r */
\r std::string result;
\r /** Time-to-live value of the result
\r */
\r unsigned long ttl;
\r /** The original request, a hostname or IP address
\r */
\r std::string original;
\r\r /** Build a DNS result.
\r * @param i The request ID
\r * @param res The request result, a hostname or IP
\r * @param timetolive The request time-to-live
\r * @param orig The original request, a hostname or IP
\r */
\r DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig) : id(i), result(res), ttl(timetolive), original(orig) { }
\r};
\r\r/**
\r * Information on a completed lookup, used internally
\r */
\rtypedef std::pair<unsigned char*, std::string> DNSInfo;
\r\r/** Cached item stored in the query cache.
\r */
\rclass CoreExport CachedQuery
\r{
\r public:
\r /** The cached result data, an IP or hostname
\r */
\r std::string data;
\r /** The time when the item is due to expire
\r */
\r time_t expires;
\r\r /** Build a cached query
\r * @param res The result data, an IP or hostname
\r * @param ttl The time-to-live value of the query result
\r */
\r CachedQuery(const std::string &res, unsigned int ttl) : data(res)
\r {
\r expires = time(NULL) + ttl;
\r }
\r\r /** Returns the number of seconds remaining before this
\r * cache item has expired and should be removed.
\r */
\r int CalcTTLRemaining()
\r {
\r int n = (int)expires - (int)time(NULL);
\r return (n < 0 ? 0 : n);
\r }
\r};
\r\r/** DNS cache information. Holds IPs mapped to hostnames, and hostnames mapped to IPs.
\r */
\r#ifndef WIN32
\rtypedef nspace::hash_map<irc::string, CachedQuery, nspace::hash<irc::string> > dnscache;
\r#else
\rtypedef nspace::hash_map<irc::string, CachedQuery, nspace::hash_compare<irc::string> > dnscache;
\r#endif
\r\r/**
\r * Error types that class Resolver can emit to its error method.
\r */
\renum ResolverError
\r{
\r RESOLVER_NOERROR = 0,
\r RESOLVER_NSDOWN = 1,
\r RESOLVER_NXDOMAIN = 2,
\r RESOLVER_NOTREADY = 3,
\r RESOLVER_BADIP = 4,
\r RESOLVER_TIMEOUT = 5,
\r RESLOVER_FORCEUNLOAD = 6
\r};
\r\r/**
\r * A DNS request
\r */
\rclass DNSRequest;
\r\r/**
\r * A DNS packet header
\r */
\rclass DNSHeader;
\r\r/**
\r * A DNS Resource Record (rr)
\r */
\rstruct ResourceRecord;
\r\r/**
\r * Query and resource record types
\r */
\renum QueryType
\r{
\r DNS_QUERY_NONE = 0, /* Uninitialized Query */
\r DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */
\r DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */
\r DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */
\r DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */
\r\r DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */
\r DNS_QUERY_PTR6 = 0xFFFE /* Force 'PTR' to use IPV6 scemantics */
\r};
\r\r#ifdef IPV6
\rconst QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA;
\r#else
\rconst QueryType DNS_QUERY_FORWARD = DNS_QUERY_A;
\r#endif
\rconst QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR;
\r/**
\r * Used internally to force PTR lookups to use a certain protocol scemantics,
\r * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
\r */
\renum ForceProtocol
\r{
\r PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */
\r PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */
\r};
\r\r/**
\r * The Resolver class is a high-level abstraction for resolving DNS entries.
\r * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
\r * also be able to do those, transparent of protocols. Module developers must
\r * extend this class via inheritence, and then insert a pointer to their derived
\r * class into the core using Server::AddResolver(). Once you have done this,
\r * the class will be able to receive callbacks. There are two callbacks which
\r * can occur by calling virtual methods, one is a success situation, and the other
\r * an error situation.
\r */
\rclass CoreExport Resolver : public Extensible
\r{
\r protected:
\r /**
\r * Pointer to creator
\r */
\r InspIRCd* ServerInstance;
\r /**
\r * Pointer to creator module (if any, or NULL)
\r */
\r Module* Creator;
\r /**
\r * The input data, either a host or an IP address
\r */
\r std::string input;
\r /**
\r * True if a forward lookup is being performed, false if otherwise
\r */
\r QueryType querytype;
\r /**
\r * The DNS erver being used for lookups. If this is an empty string,
\r * the value of ServerConfig::DNSServer is used instead.
\r */
\r std::string server;
\r /**
\r * The ID allocated to your lookup. This is a pseudo-random number
\r * between 0 and 65535, a value of -1 indicating a failure.
\r * The core uses this to route results to the correct objects.
\r */
\r int myid;
\r\r /**
\r * Cached result, if there is one
\r */
\r CachedQuery *CQ;
\r\r /**
\r * Time left before cache expiry
\r */
\r int time_left;
\r public:
\r /**
\r * Initiate DNS lookup. Your class should not attempt to delete or free these
\r * objects, as the core will do this for you. They must always be created upon
\r * the heap using new, as you cannot be sure at what time they will be deleted.
\r * Allocating them on the stack or attempting to delete them yourself could cause
\r * the object to go 'out of scope' and cause a segfault in the core if the result
\r * arrives at a later time.
\r * @param source The IP or hostname to resolve
\r * @param qt The query type to perform. If you just want to perform a forward
\r * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use
\r * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically
\r * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve
\r * a specific record type, resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
\r * is supported. Use one of the QueryType enum values to initiate this type of
\r * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
\r * wether InspIRCd is built with ipv6 support.
\r * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is
\r * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs,
\r * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs,
\r * e.g. x.x.x.x.in-addr.arpa. This translation is automatic.
\r * To get around this automatic behaviour, you must use one of the values
\r * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup,
\r * irrespective of what protocol InspIRCd has been built for.
\r * @param cached The constructor will set this boolean to true or false depending
\r * on whether the DNS lookup you are attempting is cached (and not expired) or not.
\r * If the value is cached, upon return this will be set to true, otherwise it will
\r * be set to false. You should pass this value to InspIRCd::AddResolver(), which
\r * will then influence the behaviour of the method and determine whether a cached
\r * or non-cached result is obtained. The value in this variable is always correct
\r * for the given request when the constructor exits.
\r * @param creator See the note below.
\r * @throw ModuleException This class may throw an instance of ModuleException, in the
\r * event a lookup could not be allocated, or a similar hard error occurs such as
\r * the network being down. This will also be thrown if an invalid IP address is
\r * passed when resolving a 'PTR' record.
\r *
\r * NOTE: If you are instantiating your DNS lookup from a module, you should set the
\r * value of creator to point at your Module class. This way if your module is unloaded
\r * whilst lookups are in progress, they can be safely removed and your module will not
\r * crash the server.
\r */
\r Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, bool &cached, Module* creator = NULL);
\r\r /**
\r * The default destructor does nothing.
\r */
\r virtual ~Resolver();
\r /**
\r * When your lookup completes, this method will be called.
\r * @param result The resulting DNS lookup, either an IP address or a hostname.
\r * @param ttl The time-to-live value of the result, in the instance of a cached
\r * result, this is the number of seconds remaining before refresh/expiry.
\r * @param cached True if the result is a cached result, false if it was requested
\r * from the DNS server.
\r */
\r virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached) = 0;
\r /**
\r * If an error occurs (such as NXDOMAIN, no domain name found) then this method
\r * will be called.
\r * @param e A ResolverError enum containing the error type which has occured.
\r * @param errormessage The error text of the error that occured.
\r */
\r virtual void OnError(ResolverError e, const std::string &errormessage);
\r /**
\r * Returns the id value of this class. This is primarily used by the core
\r * to determine where in various tables to place a pointer to your class, but it
\r * is safe to call and use this method.
\r * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
\r * from 0 to 65535. If there is an issue and the core cannot send your request,
\r * this method will return -1.
\r */
\r int GetId();
\r /**
\r * Returns the creator module, or NULL
\r */
\r Module* GetCreator();
\r /**
\r * If the result is a cached result, this triggers the objects
\r * OnLookupComplete. This is done because it is not safe to call
\r * the abstract virtual method from the constructor.
\r */
\r void TriggerCachedResult();
\r};
\r\r/** DNS is a singleton class used by the core to dispatch dns
\r * requests to the dns server, and route incoming dns replies
\r * back to Resolver objects, based upon the request ID. You
\r * should never use this class yourself.
\r */
\rclass CoreExport DNS : public EventHandler
\r{
\r private:
\r\r /**
\r * Creator/Owner object
\r */
\r InspIRCd* ServerInstance;
\r\r /**
\r * The maximum value of a dns request id,
\r * 16 bits wide, 0xFFFF.
\r */
\r static const int MAX_REQUEST_ID = 0xFFFF;
\r\r /**
\r * A counter used to form part of the pseudo-random id
\r */
\r int currid;
\r\r /**
\r * We have to turn off a few checks on received packets
\r * when people are using 4in6 (e.g. ::ffff:xxxx). This is
\r * a temporary kludge, Please let me know if you know how
\r * to fix it.
\r */
\r bool ip6munge;
\r\r /**
\r * Currently cached items
\r */
\r dnscache* cache;
\r\r /** A timer which ticks every hour to remove expired
\r * items from the DNS cache.
\r */
\r class CacheTimer* PruneTimer;
\r\r /**
\r * Build a dns packet payload
\r */
\r int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
\r\r public:
\r\r /**
\r * Server address being used currently
\r */
\r int socketfamily;
\r#ifdef IPV6
\r in6_addr myserver6;
\r#endif
\r in_addr myserver4;
\r\r /**
\r * Currently active Resolver classes
\r */
\r Resolver* Classes[MAX_REQUEST_ID];
\r\r /**
\r * Requests that are currently 'in flight'
\r */
\r DNSRequest* requests[MAX_REQUEST_ID];
\r\r /**
\r * The port number DNS requests are made on,
\r * and replies have as a source-port number.
\r */
\r static const int QUERY_PORT = 53;
\r\r /**
\r * Fill an rr (resource record) with data from input
\r */
\r static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
\r\r /**
\r * Fill a header with data from input limited by a length
\r */
\r static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
\r\r /**
\r * Empty out a header into a data stream ready for transmission "on the wire"
\r */
\r static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
\r\r /**
\r * Start the lookup of an ipv4 from a hostname
\r */
\r int GetIP(const char* name);
\r\r /**
\r * Start the lookup of a hostname from an ip,
\r * always using the protocol inspircd is built for,
\r * e.g. use ipv6 reverse lookup when built for ipv6,
\r * or ipv4 lookup when built for ipv4.
\r */
\r int GetName(const insp_inaddr* ip);
\r\r /**
\r * Start lookup of a hostname from an ip, but
\r * force a specific protocol to be used for the lookup
\r * for example to perform an ipv6 reverse lookup.
\r */
\r int GetNameForce(const char *ip, ForceProtocol fp);
\r\r /**
\r * Start lookup of an ipv6 from a hostname
\r */
\r int GetIP6(const char *name);
\r\r /**
\r * Start lookup of a CNAME from another hostname
\r */
\r int GetCName(const char* alias);
\r\r /**
\r * Fetch the result string (an ip or host)
\r * and/or an error message to go with it.
\r */
\r DNSResult GetResult();
\r\r /**
\r * Handle a SocketEngine read event
\r * Inherited from EventHandler
\r */
\r void HandleEvent(EventType et, int errornum = 0);
\r\r /**
\r * Add a Resolver* to the list of active classes
\r */
\r bool AddResolverClass(Resolver* r);
\r\r /**
\r * Add a query to the list to be sent
\r */
\r DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
\r\r /**
\r * The constructor initialises the dns socket,
\r * and clears the request lists.
\r */
\r DNS(InspIRCd* Instance);
\r\r /**
\r * Re-initialize the DNS subsystem.
\r */
\r void Rehash();
\r\r /**
\r * Destructor
\r */
\r ~DNS();
\r\r /** Portable random number generator, generates
\r * its random number from the ircd stats counters,
\r * effective user id, time of day and the rollover
\r * counter (currid)
\r */
\r unsigned long PRNG();
\r\r /**
\r * Turn an in6_addr into a .ip6.arpa domain
\r */
\r static void MakeIP6Int(char* query, const in6_addr *ip);
\r\r /**
\r * Clean out all dns resolvers owned by a particular
\r * module, to make unloading a module safe if there
\r * are dns requests currently in progress.
\r */
\r void CleanResolvers(Module* module);
\r\r /** Return the cached value of an IP or hostname
\r * @param source An IP or hostname to find in the cache.
\r * @return A pointer to a CachedQuery if the item exists,
\r * otherwise NULL.
\r */
\r CachedQuery* GetCache(const std::string &source);
\r\r /** Delete a cached item from the DNS cache.
\r * @param source An IP or hostname to remove
\r */
\r void DelCache(const std::string &source);
\r\r /** Clear all items from the DNS cache immediately.
\r */
\r int ClearCache();
\r\r /** Prune the DNS cache, e.g. remove all expired
\r * items and rehash the cache buckets, but leave
\r * items in the hash which are still valid.
\r */
\r int PruneCache();
\r};
\r\r#endif
\r\r