/*
-dns.h - dns library declarations based on firedns Copyright (C) 2002 Ian Gulliver
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ * Copyright (C) 2009 Daniel De Graaf <danieldg@inspircd.org>
+ * Copyright (C) 2005-2008 Craig Edwards <craigedwards@brainbox.cc>
+ * Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
+ *
+ * This file is part of InspIRCd. InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+/*
+dns.h - dns library very very loosely based on
+firedns, Copyright (C) 2002 Ian Gulliver
This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License as
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
-#ifndef _DNS_H
-#define _DNS_H
+#ifndef DNS_H
+#define DNS_H
-#include <string>
-#include "inspircd_config.h"
#include "socket.h"
-#include "base.h"
+#include "hashcomp.h"
+
+/**
+ * Query and resource record types
+ */
+enum QueryType
+{
+ /** Uninitialized Query */
+ DNS_QUERY_NONE = 0,
+ /** 'A' record: an ipv4 address */
+ DNS_QUERY_A = 1,
+ /** 'CNAME' record: An alias */
+ DNS_QUERY_CNAME = 5,
+ /** 'PTR' record: a hostname */
+ DNS_QUERY_PTR = 12,
+ /** 'AAAA' record: an ipv6 address */
+ DNS_QUERY_AAAA = 28,
+
+ /** Force 'PTR' to use IPV4 scemantics */
+ DNS_QUERY_PTR4 = 0xFFFD,
+ /** Force 'PTR' to use IPV6 scemantics */
+ DNS_QUERY_PTR6 = 0xFFFE
+};
+
+/**
+ * Result status, used internally
+ */
+class CoreExport DNSResult
+{
+ public:
+ /** Result ID
+ */
+ int id;
+ /** Result body, a hostname or IP address
+ */
+ std::string result;
+ /** Time-to-live value of the result
+ */
+ unsigned long ttl;
+ /** The original request, a hostname or IP address
+ */
+ std::string original;
+ /** The type of the request
+ */
+ QueryType type;
+
+ /** Build a DNS result.
+ * @param i The request ID
+ * @param res The request result, a hostname or IP
+ * @param timetolive The request time-to-live
+ * @param orig The original request, a hostname or IP
+ * @param qt The type of DNS query this result represents.
+ */
+ DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig, QueryType qt = DNS_QUERY_NONE) : id(i), result(res), ttl(timetolive), original(orig), type(qt) { }
+};
+
+/**
+ * Information on a completed lookup, used internally
+ */
+typedef std::pair<unsigned char*, std::string> DNSInfo;
-struct dns_ip4list
+/** Cached item stored in the query cache.
+ */
+class CoreExport CachedQuery
{
- insp_inaddr ip;
- dns_ip4list *next;
+ public:
+ /** The cached result data, an IP or hostname
+ */
+ std::string data;
+ /** The type of result this is
+ */
+ QueryType type;
+ /** The time when the item is due to expire
+ */
+ time_t expires;
+
+ /** Build a cached query
+ * @param res The result data, an IP or hostname
+ * @param qt The type of DNS query this instance represents.
+ * @param ttl The time-to-live value of the query result
+ */
+ CachedQuery(const std::string &res, QueryType qt, unsigned int ttl);
+
+ /** Returns the number of seconds remaining before this
+ * cache item has expired and should be removed.
+ */
+ int CalcTTLRemaining();
};
+/** DNS cache information. Holds IPs mapped to hostnames, and hostnames mapped to IPs.
+ */
+typedef nspace::hash_map<irc::string, CachedQuery, irc::hash> dnscache;
+
/**
* Error types that class Resolver can emit to its error method.
*/
RESOLVER_NOERROR = 0,
RESOLVER_NSDOWN = 1,
RESOLVER_NXDOMAIN = 2,
- RESOLVER_NOTREADY = 3
+ RESOLVER_BADIP = 3,
+ RESOLVER_TIMEOUT = 4,
+ RESOLVER_FORCEUNLOAD = 5
};
-
-/** The DNS class allows fast nonblocking resolution of hostnames
- * and ip addresses. It is based heavily upon firedns by Ian Gulliver.
- * Modules SHOULD avoid using this class to resolve hostnames and IP
- * addresses, as it is a low-level wrapper around the UDP socket routines
- * and is probably not abstracted enough for real use. Please see the
- * Resolver class if you wish to resolve hostnames.
+/**
+ * Used internally to force PTR lookups to use a certain protocol scemantics,
+ * e.g. x.x.x.x.in-addr.arpa for v4, and *.ip6.arpa for v6.
*/
-class DNS : public Extensible
+enum ForceProtocol
{
- private:
- insp_inaddr *binip;
- unsigned char* result;
- unsigned char localbuf[1024];
- int t;
- int myid;
- public:
- int dns_getip4(const char* name);
- int dns_getname4(const insp_inaddr* ip);
- int dns_getresult();
- DNS();
- ~DNS();
+ /** Forced to use ipv4 */
+ PROTOCOL_IPV4 = 0,
+ /** Forced to use ipv6 */
+ PROTOCOL_IPV6 = 1
};
/**
* The Resolver class is a high-level abstraction for resolving DNS entries.
- * It can do forward and reverse IPv4 lookups, and when IPv6 is supported, will
+ * It can do forward and reverse IPv4 lookups, and where IPv6 is supported, will
* also be able to do those, transparent of protocols. Module developers must
* extend this class via inheritence, and then insert a pointer to their derived
* class into the core using Server::AddResolver(). Once you have done this,
* can occur by calling virtual methods, one is a success situation, and the other
* an error situation.
*/
-class Resolver : public Extensible
+class CoreExport Resolver
{
- private:
+ protected:
/**
- * The lowlevel DNS object used by Resolver
+ * Pointer to creator module (if any, or NULL)
*/
- DNS Query;
+ ModuleRef Creator;
/**
* The input data, either a host or an IP address
*/
/**
* True if a forward lookup is being performed, false if otherwise
*/
- bool fwd;
+ QueryType querytype;
/**
* The DNS erver being used for lookups. If this is an empty string,
* the value of ServerConfig::DNSServer is used instead.
*/
std::string server;
/**
- * The file descriptor used for the DNS lookup
+ * The ID allocated to your lookup. This is a pseudo-random number
+ * between 0 and 65535, a value of -1 indicating a failure.
+ * The core uses this to route results to the correct objects.
*/
int myid;
+
/**
- * The output data, e.g. a hostname or an IP.
+ * Cached result, if there is one
*/
- std::string result;
+ CachedQuery *CQ;
+
+ /**
+ * Time left before cache expiry
+ */
+ int time_left;
+
public:
/**
* Initiate DNS lookup. Your class should not attempt to delete or free these
* the object to go 'out of scope' and cause a segfault in the core if the result
* arrives at a later time.
* @param source The IP or hostname to resolve
- * @param forward Set to true to perform a forward lookup (hostname to ip) or false
- * to perform a reverse lookup (ip to hostname). Lookups on A records and PTR
- * records are supported. CNAME and MX are not supported by this resolver.
- * @param dnsserver This optional parameter specifies an alterate nameserver to use.
- * If it is not specified, or is an empty string, the value of ServerConfig::DNSServer
- * is used instead.
+ * @param qt The query type to perform. Resolution of 'A', 'AAAA', 'PTR' and 'CNAME' records
+ * is supported. Use one of the QueryType enum values to initiate this type of
+ * lookup. Resolution of 'AAAA' ipv6 records is always supported, regardless of
+ * wether InspIRCd is built with ipv6 support.
+ * To look up reverse records, specify one of DNS_QUERY_PTR4 or DNS_QUERY_PTR6 depending
+ * on the type of address you are looking up.
+ * @param cached The constructor will set this boolean to true or false depending
+ * on whether the DNS lookup you are attempting is cached (and not expired) or not.
+ * If the value is cached, upon return this will be set to true, otherwise it will
+ * be set to false. You should pass this value to InspIRCd::AddResolver(), which
+ * will then influence the behaviour of the method and determine whether a cached
+ * or non-cached result is obtained. The value in this variable is always correct
+ * for the given request when the constructor exits.
+ * @param creator See the note below.
* @throw ModuleException This class may throw an instance of ModuleException, in the
- * event there are no more file descriptors, or a similar hard error occurs such as
- * the network being down.
+ * event a lookup could not be allocated, or a similar hard error occurs such as
+ * the network being down. This will also be thrown if an invalid IP address is
+ * passed when resolving a 'PTR' record.
+ *
+ * NOTE: If you are instantiating your DNS lookup from a module, you should set the
+ * value of creator to point at your Module class. This way if your module is unloaded
+ * whilst lookups are in progress, they can be safely removed and your module will not
+ * crash the server.
*/
- Resolver(const std::string &source, bool forward, const std::string &dnsserver);
+ Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator);
+
/**
* The default destructor does nothing.
*/
virtual ~Resolver();
+
/**
* When your lookup completes, this method will be called.
* @param result The resulting DNS lookup, either an IP address or a hostname.
+ * @param ttl The time-to-live value of the result, in the instance of a cached
+ * result, this is the number of seconds remaining before refresh/expiry.
+ * @param cached True if the result is a cached result, false if it was requested
+ * from the DNS server.
*/
- virtual void OnLookupComplete(const std::string &result);
+ virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached) = 0;
+
/**
* If an error occurs (such as NXDOMAIN, no domain name found) then this method
* will be called.
* @param e A ResolverError enum containing the error type which has occured.
+ * @param errormessage The error text of the error that occured.
*/
- virtual void OnError(ResolverError e);
- /**
- * This method is called by the core when the object's file descriptor is ready
- * for reading, and will then dispatch a call to either OnLookupComplete or
- * OnError. You should never call this method yourself.
- */
- bool ProcessResult();
+ virtual void OnError(ResolverError e, const std::string &errormessage);
+
/**
- * Returns the file descriptor of this class. This is primarily used by the core
+ * Returns the id value of this class. This is primarily used by the core
* to determine where in various tables to place a pointer to your class, but it
* is safe to call and use this method.
+ * As specified in RFC1035, each dns request has a 16 bit ID value, ranging
+ * from 0 to 65535. If there is an issue and the core cannot send your request,
+ * this method will return -1.
*/
int GetId();
+
+ /**
+ * Returns the creator module, or NULL
+ */
+ Module* GetCreator();
+
+ /**
+ * If the result is a cached result, this triggers the objects
+ * OnLookupComplete. This is done because it is not safe to call
+ * the abstract virtual method from the constructor.
+ */
+ void TriggerCachedResult();
};
-/**
- * Clear the pointer table used for Resolver classes
+/** DNS is a singleton class used by the core to dispatch dns
+ * requests to the dns server, and route incoming dns replies
+ * back to Resolver objects, based upon the request ID. You
+ * should never use this class yourself.
*/
-void init_dns();
-/**
- * Deal with a Resolver class which has become writeable
- */
-void dns_deal_with_classes(int fd);
-/**
- * Add a resolver class to our active table
- */
-bool dns_add_class(Resolver* r);
+class CoreExport DNS : public EventHandler
+{
+ private:
-#ifdef THREADED_DNS
-/** This is the handler function for multi-threaded DNS.
- * It cannot be a class member as pthread will not let us
- * create a thread whos handler function is a member of
- * a class (ugh).
- */
-void* dns_task(void* arg);
-#endif
+ /**
+ * The maximum value of a dns request id,
+ * 16 bits wide, 0xFFFF.
+ */
+ static const int MAX_REQUEST_ID = 0xFFFF;
+
+ /** Maximum number of entries in cache
+ */
+ static const unsigned int MAX_CACHE_SIZE = 1000;
+
+ /**
+ * Currently cached items
+ */
+ dnscache* cache;
+
+ /** A timer which ticks every hour to remove expired
+ * items from the DNS cache.
+ */
+ class CacheTimer* PruneTimer;
+
+ /**
+ * Build a dns packet payload
+ */
+ int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload);
+
+ public:
+
+ irc::sockets::sockaddrs myserver;
+
+ /**
+ * Currently active Resolver classes
+ */
+ Resolver* Classes[MAX_REQUEST_ID];
+
+ /**
+ * Requests that are currently 'in flight'
+ */
+ DNSRequest* requests[MAX_REQUEST_ID];
+
+ /**
+ * The port number DNS requests are made on,
+ * and replies have as a source-port number.
+ */
+ static const int QUERY_PORT = 53;
+
+ /**
+ * Fill an rr (resource record) with data from input
+ */
+ static void FillResourceRecord(ResourceRecord* rr, const unsigned char* input);
+
+ /**
+ * Fill a header with data from input limited by a length
+ */
+ static void FillHeader(DNSHeader *header, const unsigned char *input, const int length);
+
+ /**
+ * Empty out a header into a data stream ready for transmission "on the wire"
+ */
+ static void EmptyHeader(unsigned char *output, const DNSHeader *header, const int length);
+
+ /**
+ * Start the lookup of an ipv4 from a hostname
+ */
+ int GetIP(const char* name);
+
+ /**
+ * Start lookup of a hostname from an ip, but
+ * force a specific protocol to be used for the lookup
+ * for example to perform an ipv6 reverse lookup.
+ */
+ int GetNameForce(const char *ip, ForceProtocol fp);
+
+ /**
+ * Start lookup of an ipv6 from a hostname
+ */
+ int GetIP6(const char *name);
+
+ /**
+ * Start lookup of a CNAME from another hostname
+ */
+ int GetCName(const char* alias);
+
+ /**
+ * Fetch the result string (an ip or host)
+ * and/or an error message to go with it.
+ */
+ DNSResult GetResult();
+
+ /**
+ * Handle a SocketEngine read event
+ * Inherited from EventHandler
+ */
+ void HandleEvent(EventType et, int errornum = 0);
+
+ /**
+ * Add a Resolver* to the list of active classes
+ */
+ bool AddResolverClass(Resolver* r);
+
+ /**
+ * Add a query to the list to be sent
+ */
+ DNSRequest* AddQuery(DNSHeader *header, int &id, const char* original);
+
+ /**
+ * The constructor initialises the dns socket,
+ * and clears the request lists.
+ */
+ DNS();
+
+ /**
+ * Re-initialize the DNS subsystem.
+ */
+ void Rehash();
+
+ /**
+ * Destructor
+ */
+ ~DNS();
+
+ /**
+ * Turn an in6_addr into a .ip6.arpa domain
+ */
+ static void MakeIP6Int(char* query, const in6_addr *ip);
+
+ /**
+ * Clean out all dns resolvers owned by a particular
+ * module, to make unloading a module safe if there
+ * are dns requests currently in progress.
+ */
+ void CleanResolvers(Module* module);
+
+ /** Return the cached value of an IP or hostname
+ * @param source An IP or hostname to find in the cache.
+ * @return A pointer to a CachedQuery if the item exists,
+ * otherwise NULL.
+ */
+ CachedQuery* GetCache(const std::string &source);
+
+ /** Delete a cached item from the DNS cache.
+ * @param source An IP or hostname to remove
+ */
+ void DelCache(const std::string &source);
+
+ /** Clear all items from the DNS cache immediately.
+ */
+ int ClearCache();
+
+ /** Prune the DNS cache, e.g. remove all expired
+ * items and rehash the cache buckets, but leave
+ * items in the hash which are still valid.
+ */
+ int PruneCache();
+};
#endif
+
projects / user / henk / code / inspircd.git / blobdiff