X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=include%2Fdns.h;h=76a69b6e453043b51b25331ae0acdd392e6b6f7e;hb=67a4a9b62355ea57a2f4521ca5fc53bd4eac3a1f;hp=5823004795ddd1f8692c867f97443ef24efaa9f4;hpb=b4f7f64413022c0cdd2900760748d4b24a8f68ec;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/include/dns.h b/include/dns.h index 582300479..76a69b6e4 100644 --- a/include/dns.h +++ b/include/dns.h @@ -1,5 +1,19 @@ +/* +------------------------------------+ + * | Inspire Internet Relay Chat Daemon | + * +------------------------------------+ + * + * InspIRCd: (C) 2002-2009 InspIRCd Development Team + * See: http://wiki.inspircd.org/Credits + * + * This program is free but copyrighted software; see + * the file COPYING for details. + * + * --------------------------------------------------- + */ + /* -dns.h - dns library declarations based on firedns Copyright (C) 2002 Ian Gulliver +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 @@ -18,12 +32,82 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA #ifndef _DNS_H #define _DNS_H -#include -#include "inspircd_config.h" #include "socket.h" -#include "base.h" +#include "hashcomp.h" + +class Module; + +/** + * Result status, used internally + */ +class CoreExport DNSResult : public classbase +{ + 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; -typedef std::pair DNSResult; + /** 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 + */ + DNSResult(int i, const std::string &res, unsigned long timetolive, const std::string &orig) : id(i), result(res), ttl(timetolive), original(orig) { } +}; + +/** + * Information on a completed lookup, used internally + */ +typedef std::pair DNSInfo; + +/** Cached item stored in the query cache. + */ +class CoreExport CachedQuery : public classbase +{ + public: + /** The cached result data, an IP or hostname + */ + std::string data; + /** 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 ttl The time-to-live value of the query result + */ + CachedQuery(const std::string &res, unsigned int ttl) : data(res) + { + expires = time(NULL) + ttl; + } + + /** Returns the number of seconds remaining before this + * cache item has expired and should be removed. + */ + int CalcTTLRemaining() + { + int n = (int)expires - (int)time(NULL); + return (n < 0 ? 0 : n); + } +}; + +/** DNS cache information. Holds IPs mapped to hostnames, and hostnames mapped to IPs. + */ +#if defined(WINDOWS) && !defined(HASHMAP_DEPRECATED) +typedef nspace::hash_map > dnscache; +#else +typedef nspace::hash_map > dnscache; +#endif /** * Error types that class Resolver can emit to its error method. @@ -33,28 +117,63 @@ enum ResolverError RESOLVER_NOERROR = 0, RESOLVER_NSDOWN = 1, RESOLVER_NXDOMAIN = 2, - RESOLVER_NOTREADY = 3 + RESOLVER_BADIP = 3, + RESOLVER_TIMEOUT = 4, + RESOLVER_FORCEUNLOAD = 5 }; +/** + * A DNS request + */ +class DNSRequest; -/** 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. +/** + * A DNS packet header + */ +class DNSHeader; + +/** + * A DNS Resource Record (rr) + */ +struct ResourceRecord; + +/** + * Query and resource record types */ -class DNS : public Extensible +enum QueryType { - public: - int dns_getip4(const char* name); - int dns_getname4(const insp_inaddr* ip); - DNSResult dns_getresult(); - DNS(); - ~DNS(); + /** 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 +}; + +/** + * 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. + */ +enum ForceProtocol +{ + /** 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, @@ -62,9 +181,13 @@ class DNS : public Extensible * can occur by calling virtual methods, one is a success situation, and the other * an error situation. */ -class Resolver : public Extensible +class CoreExport Resolver : public Extensible { protected: + /** + * Pointer to creator module (if any, or NULL) + */ + Module* Creator; /** * The input data, either a host or an IP address */ @@ -72,18 +195,29 @@ class Resolver : public Extensible /** * 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 ID allocated to your lookup. This is a pseud-random number + * 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; + + /** + * Cached result, if there is one + */ + CachedQuery *CQ; + + /** + * Time left before cache expiry + */ + int time_left; + public: /** * Initiate DNS lookup. Your class should not attempt to delete or free these @@ -93,37 +227,55 @@ class Resolver : public Extensible * 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. - * If InspIRCd is compiled with ipv6 support, lookups on AAAA records are preferred - * and supported over A records. + * @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 a lookup could not be allocated, or a similar hard error occurs such as - * the network being down. + * 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); + Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator = NULL); + /** * 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(const std::string &result); + virtual void OnError(ResolverError e, const std::string &errormessage); + /** * 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 @@ -133,21 +285,191 @@ class Resolver : public Extensible * 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, - * translate ServerConfig::DNSServer into an insp_inaddr, - * establish binding on UDP socket for DNS requests. - */ -void init_dns(); -/** - * Deal with a Resolver class which has become readable - */ -void dns_deal_with_classes(int fd); -/** - * Add a resolver class to our active table +/** 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. */ -bool dns_add_class(Resolver* r); +class CoreExport DNS : public EventHandler +{ + private: + + /** + * The maximum value of a dns request id, + * 16 bits wide, 0xFFFF. + */ + static const int MAX_REQUEST_ID = 0xFFFF; + + /** + * A counter used to form part of the pseudo-random id + */ + int currid; + + /** + * 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(); + + /** Portable random number generator, generates + * its random number from the ircd stats counters, + * effective user id, time of day and the rollover + * counter (currid) + */ + unsigned long PRNG(); + + /** + * 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 +