X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=include%2Fdns.h;h=4087e2476eef2bef4f176b1d583683bfa1236df5;hb=696ee9ff66bb94be2229bfa9c3dc288affc38a72;hp=d0cb97804c2a8dd659593a59a44739410fa1a4cd;hpb=f96ddd39748f283768217fb1a3cdd3a7cbde353a;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/include/dns.h b/include/dns.h index d0cb97804..4087e2476 100644 --- a/include/dns.h +++ b/include/dns.h @@ -1,5 +1,19 @@ +/* +------------------------------------+ + * | Inspire Internet Relay Chat Daemon | + * +------------------------------------+ + * + * InspIRCd: (C) 2002-2007 InspIRCd Development Team + * See: http://www.inspircd.org/wiki/index.php/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 @@ -18,78 +32,361 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA #ifndef _DNS_H #define _DNS_H -#include -#include -#include #include +#include "inspircd_config.h" +#include "base.h" +#include "socketengine.h" +#include "socket.h" + +using namespace std; +using irc::sockets::insp_aton; +using irc::sockets::insp_ntoa; +using irc::sockets::insp_sockaddr; +using irc::sockets::insp_inaddr; + +class InspIRCd; +class Module; + +/** + * 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. + */ +enum ResolverError +{ + RESOLVER_NOERROR = 0, + RESOLVER_NSDOWN = 1, + RESOLVER_NXDOMAIN = 2, + RESOLVER_NOTREADY = 3, + RESOLVER_BADIP = 4, + RESOLVER_TIMEOUT = 5, + RESLOVER_FORCEUNLOAD = 6 +}; + +/** + * A DNS request + */ +class DNSRequest; + +/** + * A DNS packet header + */ +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; + +/** + * Query and resource record types + */ +enum QueryType +{ + DNS_QUERY_NONE = 0, /* Uninitialized Query */ + DNS_QUERY_A = 1, /* 'A' record: an ipv4 address */ + DNS_QUERY_CNAME = 5, /* 'CNAME' record: An alias */ + DNS_QUERY_PTR = 12, /* 'PTR' record: a hostname */ + DNS_QUERY_AAAA = 28, /* 'AAAA' record: an ipv6 address */ -struct dns_ip4list { - in_addr ip; - dns_ip4list *next; + DNS_QUERY_PTR4 = 0xFFFD, /* Force 'PTR' to use IPV4 scemantics */ + DNS_QUERY_PTR6 = 0xFFFE, /* Force 'PTR' to use IPV6 scemantics */ }; +#ifdef IPV6 +const QueryType DNS_QUERY_FORWARD = DNS_QUERY_AAAA; +const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR; +#else +const QueryType DNS_QUERY_FORWARD = DNS_QUERY_A; +const QueryType DNS_QUERY_REVERSE = DNS_QUERY_PTR; +#endif + +/** + * 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 +{ + PROTOCOL_IPV4 = 0, /* Forced to use ipv4 */ + PROTOCOL_IPV6 = 1 /* Forced to use ipv6 */ +}; -/** 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 +class Resolver : public Extensible { -private: - in_addr *binip; - char* result; - int t; - void dns_init(); - int fd; - 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(std::string dnsserver); - /** The destructor frees all used structures. + protected: + /** + * Pointer to creator */ - ~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. + InspIRCd* ServerInstance; + /** + * Pointer to creator module (if any, or NULL) + */ + Module* 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 + */ + 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 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; + 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. If you just want to perform a forward + * or reverse lookup, and you don't care wether you get ipv4 or ipv6, then use + * the constants DNS_QUERY_FORWARD and DNS_QUERY_REVERSE, which automatically + * select from 'A' record or 'AAAA' record lookups. However, if you want to resolve + * a specific record type, 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. + * If you attempt to resolve a 'PTR' record using DNS_QUERY_PTR, and InspIRCd is + * built with ipv6 support, the 'PTR' record will be formatted to ipv6 specs, + * e.g. x.x.x.x.x....ip6.arpa. otherwise it will be formatted to ipv4 specs, + * e.g. x.x.x.x.in-addr.arpa. This translation is automatic. + * To get around this automatic behaviour, you must use one of the values + * DNS_QUERY_PTR4 or DNS_QUERY_PTR6 to force ipv4 or ipv6 behaviour on the lookup, + * irrespective of what protocol InspIRCd has been built for. + * @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. + */ + Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, 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. + */ + 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, 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 GetId(); + + /** + * Returns the creator module, or NULL + */ + Module* GetCreator(); +}; + +/** 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 DNS : public EventHandler +{ + private: + + InspIRCd* ServerInstance; + + /** + * 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; + + /** + * A counter used to form part of the pseudo-random id + */ + int currid; + + /** + * We have to turn off a few checks on received packets + * when people are using 4in6 (e.g. ::ffff:xxxx). This is + * a temporary kludge, Please let me know if you know how + * to fix it. + */ + bool ip6munge; + + /** + * Build a dns packet payload + */ + int MakePayload(const char* name, const QueryType rr, const unsigned short rr_class, unsigned char* payload); + + public: + /** + * Currently active Resolver classes + */ + Resolver* Classes[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 the lookup of a hostname from an ip, + * always using the protocol inspircd is built for, + * e.g. use ipv6 reverse lookup when built for ipv6, + * or ipv4 lookup when built for ipv4. + */ + int GetName(const insp_inaddr* ip); + + /** + * 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 */ - bool ReverseLookup(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. + int GetCName(const char* alias); + + /** + * Fetch the result string (an ip or host) + * and/or an error message to go with it. */ - bool ForwardLookup(std::string host); - /** This method will return true when the lookup is completed. It uses poll internally - * to determine the status of the socket. + DNSResult GetResult(); + + /** + * Handle a SocketEngine read event + * Inherited from EventHandler */ - bool HasResult(); - /** This method returns the result of your query as a string, depending upon wether you - * called DNS::ReverseLookup() or DNS::ForwardLookup. + void HandleEvent(EventType et, int errornum = 0); + + /** + * Add a Resolver* to the list of active classes */ - std::string GetResult(); - /** 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. + bool AddResolverClass(Resolver* r); + + /** + * Add a query to the list to be sent */ - int GetFD(); - void SetNS(std::string dnsserver); + DNSRequest* AddQuery(DNSHeader *header, int &id); + + /** + * The constructor initialises the dns socket, + * and clears the request lists. + */ + DNS(InspIRCd* Instance); + + /** + * 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); }; #endif +