X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=include%2Fdns.h;h=95abaaf801f1c4b65f2351c2fb0ffe6e2c47e52c;hb=df67ab549bcc2cd53519f309110c58c00f2c935b;hp=89dd4e27068e8db832d4d2a20ea6695d8bd5eaec;hpb=b864f69ce98841fd54e2328b49e34b5be49525b8;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/include/dns.h b/include/dns.h index 89dd4e270..95abaaf80 100644 --- a/include/dns.h +++ b/include/dns.h @@ -1,5 +1,27 @@ /* -dns.h - dns library declarations based on firedns Copyright (C) 2002 Ian Gulliver + * InspIRCd -- Internet Relay Chat Daemon + * + * Copyright (C) 2009 Daniel De Graaf + * Copyright (C) 2005-2008 Craig Edwards + * Copyright (C) 2007 Dennis Friis + * + * 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 . + */ + + +/* +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 @@ -15,128 +37,413 @@ along with this program; if not, write to the Free Software 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 -#include "inspircd_config.h" #include "socket.h" -#include "base.h" +#include "hashcomp.h" -struct dns_ip4list +/** + * Query and resource record types + */ +enum QueryType { - in_addr ip; - dns_ip4list *next; + /** 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 + */ + 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 DNSInfo; + +/** Cached item stored in the query cache. + */ +class CoreExport CachedQuery +{ + 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 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 dnscache; + +/** + * Error types that class Resolver can emit to its error method. + */ enum ResolverError { RESOLVER_NOERROR = 0, RESOLVER_NSDOWN = 1, RESOLVER_NXDOMAIN = 2, - RESOLVER_NOTREADY = 3 + RESOLVER_BADIP = 3, + RESOLVER_TIMEOUT = 4, + RESOLVER_FORCEUNLOAD = 5 }; +/** + * 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 DNS class allows fast nonblocking resolution of hostnames - * and ip addresses. It is based heavily upon firedns by Ian Gulliver. +/** + * The Resolver class is a high-level abstraction for resolving DNS entries. + * 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, + * the class will be able to receive callbacks. There are two callbacks which + * can occur by calling virtual methods, one is a success situation, and the other + * an error situation. */ -class DNS : public Extensible +class CoreExport Resolver { -private: - in_addr *binip; - char* result; - char localbuf[1024]; - int t; - void dns_init(); - int myfd; - void dns_init_2(const char* dnsserver); - in_addr *dns_aton4(const char * const ipstring); - char *dns_ntoa4(const in_addr * const ip); - int dns_getip4(const char * const name); - int dns_getip4list(const char * const name); - int dns_getname4(const in_addr * const ip); - char *dns_getresult(const int fd); - in_addr *dns_aton4_s(const char * const ipstring, in_addr * const ip); - char *dns_ntoa4_s(const in_addr * const ip, char * const result); - char *dns_getresult_s(const int fd, char * const result); - in_addr *dns_aton4_r(const char * const ipstring); - char *dns_ntoa4_r(const in_addr * const ip); - char *dns_getresult_r(const int fd); -public: - /** The default constructor uses dns addresses read from /etc/resolv.conf. - * Please note that it will re-read /etc/resolv.conf for each copy of the - * class you instantiate, causing disk access and slow lookups if you create - * a lot of them. Consider passing the constructor a server address as a parameter - * instead. + protected: + /** + * Pointer to creator module (if any, or NULL) */ - DNS(); - /** This constructor accepts a dns server address. The address must be in dotted - * decimal form, e.g. 1.2.3.4. + ModuleRef Creator; + /** + * The input data, either a host or an IP address + */ + std::string input; + /** + * True if a forward lookup is being performed, false if otherwise */ - DNS(const std::string &dnsserver); - /** The destructor frees all used structures. + QueryType querytype; + /** + * The DNS erver being used for lookups. If this is an empty string, + * the value of ServerConfig::DNSServer is used instead. */ - ~DNS(); - /** This method will start the reverse lookup of an ip given in dotted decimal - * format, e.g. 1.2.3.4, and returns true if the lookup was successfully - * initiated. + std::string server; + /** + * 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 */ - bool ReverseLookup(const std::string &ip); - /** This method will start the forward lookup of a hostname, e.g. www.inspircd.org, - * and returns true if the lookup was successfully initiated. + CachedQuery *CQ; + + /** + * Time left before cache expiry */ - bool ForwardLookup(const std::string &host); - /** Used by modules to perform a dns lookup but have the socket engine poll a module, instead of the dns object directly. + int time_left; + + public: + /** + * Initiate DNS lookup. Your class should not attempt to delete or free these + * objects, as the core will do this for you. They must always be created upon + * the heap using new, as you cannot be sure at what time they will be deleted. + * Allocating them on the stack or attempting to delete them yourself could cause + * 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 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. 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. */ - bool ForwardLookupWithFD(const std::string &host, int &fd); - /** This method will return true when the lookup is completed. It uses poll internally - * to determine the status of the socket. + Resolver(const std::string &source, QueryType qt, bool &cached, Module* creator); + + /** + * The default destructor does nothing. */ - bool HasResult(); - /** This method will return true if the lookup's fd matches the one provided + 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. */ - bool HasResult(int fd); - /** This method returns the result of your query as a string, depending upon wether you - * called DNS::ReverseLookup() or DNS::ForwardLookup. + 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. */ - std::string GetResult(); - std::string GetResultIP(); - /** This method returns the file handle used by the dns query socket or zero if the - * query is invalid for some reason, e.g. the dns server not responding. + 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 + * 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 GetFD(); - void SetNS(const std::string &dnsserver); + 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(); }; -class Resolver : public Extensible +/** 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. + */ +class CoreExport DNS : public EventHandler { private: - DNS Query; - std::string input; - bool fwd; - std::string server; - int fd; - std::string result; + + /** + * The maximum value of a dns request id, + * 16 bits wide, 0xFFFF. + */ + static const int MAX_REQUEST_ID = 0xFFFF; + + /** + * 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: - Resolver(const std::string &source, bool forward, const std::string &dnsserver); - virtual ~Resolver(); - virtual void OnLookupComplete(const std::string &result); - virtual void OnError(ResolverError e); - bool ProcessResult(); - int GetFd(); -}; + irc::sockets::sockaddrs myserver; -void init_dns(); -void dns_deal_with_classes(int fd); -bool dns_add_class(Resolver* r); + /** + * Currently active Resolver classes + */ + Resolver* Classes[MAX_REQUEST_ID]; -/** 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); + /** + * 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 +