X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=include%2Fdns.h;h=41f42f46aa0019ac586e77769f81b2d2c4bd06ed;hb=30911b2ae8c8d8bdf741fc642f49956b8c9b98c0;hp=9d293884acdc5d6f9164b6668127720e678dd17e;hpb=a8b71c68dd93dab213e286dc7730e47f32beeaab;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/include/dns.h b/include/dns.h index 9d293884a..41f42f46a 100644 --- a/include/dns.h +++ b/include/dns.h @@ -1,5 +1,22 @@ +/* +------------------------------------+ + * | Inspire Internet Relay Chat Daemon | + * +------------------------------------+ + * + * InspIRCd is copyright (C) 2002-2006 ChatSpike-Dev. + * E-mail: + * + * + * + * Written by Craig Edwards, Craig McLure, and others. + * 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 @@ -23,11 +40,15 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA #include "socket.h" #include "base.h" -struct dns_ip4list -{ - in_addr ip; - dns_ip4list *next; -}; +/** + * Result status, used internally + */ +typedef std::pair DNSResult; + +/** + * Information on a completed lookup, used internally + */ +typedef std::pair DNSInfo; /** * Error types that class Resolver can emit to its error method. @@ -37,88 +58,38 @@ enum ResolverError RESOLVER_NOERROR = 0, RESOLVER_NSDOWN = 1, RESOLVER_NXDOMAIN = 2, - RESOLVER_NOTREADY = 3 + RESOLVER_NOTREADY = 3, + RESOLVER_BADIP = 4 }; +/** + * A DNS request + */ +class DNSRequest; -/** 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. +/** + * A DNS packet header */ -class DNS : public Extensible -{ -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. - */ - DNS(); - /** This constructor accepts a dns server address. The address must be in dotted - * decimal form, e.g. 1.2.3.4. - */ - DNS(const std::string &dnsserver); - /** The destructor frees all used structures. - */ - ~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. - */ - bool ReverseLookup(const std::string &ip, bool ins); - /** This method will start the forward lookup of a hostname, e.g. www.inspircd.org, - * and returns true if the lookup was successfully initiated. - */ - bool ForwardLookup(const std::string &host, bool ins); - /** Used by modules to perform a dns lookup but have the socket engine poll a module, instead of the dns object directly. - */ - 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. - */ - bool HasResult(); - /** This method will return true if the lookup's fd matches the one provided - */ - 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. - */ - 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. - */ - int GetFD(); - void SetNS(const std::string &dnsserver); -}; +class DNSHeader; + +/** + * A DNS Resource Record (rr) + */ +class ResourceRecord; + +/** + * A set of requests keyed by request id + */ +typedef std::map requestlist; + +/** + * An iterator into a set of requests + */ +typedef requestlist::iterator requestlist_iter; /** * 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, @@ -128,11 +99,7 @@ public: */ class Resolver : public Extensible { - private: - /** - * The lowlevel DNS object used by Resolver - */ - DNS Query; + protected: /** * The input data, either a host or an IP address */ @@ -147,13 +114,11 @@ class Resolver : public Extensible */ std::string server; /** - * The file descriptor used for the DNS lookup - */ - int fd; - /** - * The output data, e.g. a hostname or an IP. + * 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. */ - std::string result; + int myid; public: /** * Initiate DNS lookup. Your class should not attempt to delete or free these @@ -166,14 +131,13 @@ class Resolver : public Extensible * @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. + * If InspIRCd is compiled with ipv6 support, lookups on AAAA records are preferred + * and supported over A records. * @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 + * event a lookup could not be allocated, or a similar hard error occurs such as * the network being down. */ - Resolver(const std::string &source, bool forward, const std::string &dnsserver); + Resolver(const std::string &source, bool forward); /** * The default destructor does nothing. */ @@ -182,47 +146,147 @@ class Resolver : public Extensible * When your lookup completes, this method will be called. * @param result The resulting DNS lookup, either an IP address or a hostname. */ - virtual void OnLookupComplete(const std::string &result); + virtual void OnLookupComplete(const std::string &result) = 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); + virtual void OnError(ResolverError e, const std::string &errormessage); /** - * 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(); - /** - * 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 GetFd(); + int GetId(); }; /** - * Clear the pointer table used for Resolver classes + * Query and resource record types */ -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); +enum QueryType +{ + DNS_QUERY_A = 1, /* 'A' record: an IP address */ + DNS_QUERY_PTR = 12 /* 'PTR' record: a hostname */ +}; -#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). +/** 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* dns_task(void* arg); -#endif +class DNS : public Extensible +{ + private: + + /** + * The maximum value of a dns request id, + * 16 bits wide, 0xFFFF. + */ + static const int MAX_REQUEST_ID = 0xFFFF; + + /** + * Requests that are currently 'in flight + */ + requestlist requests; + + /** + * Server address being used currently + */ + insp_inaddr myserver; + + /** + * File descriptor being used to perform queries + */ + static int MasterSocket; + + /** + * A counter used to form part of the pseudo-random id + */ + int currid; + + /** + * Currently active Resolver classes + */ + Resolver* Classes[MAX_REQUEST_ID]; + + /** + * Build a dns packet payload + */ + int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload); + + public: + + /** + * 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); + /** + * Get the master socket fd, used internally + */ + static int GetMasterSocket(); + + /** + * Start the lookup of an ip from a hostname + */ + int GetIP(const char* name); + + /** + * Start the lookup of a hostname from an ip + */ + int GetName(const insp_inaddr* ip); + + /** + * Fetch the result string (an ip or host) + * and/or an error message to go with it. + */ + DNSResult GetResult(); + + /** + * Handle a SocketEngine read event + */ + void MarshallReads(int fd); + + /** + * 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); + + /** + * The constructor initialises the dns socket, + * and clears the request lists. + */ + DNS(); + + /** + * 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(); +}; #endif +