X-Git-Url: https://git.netwichtig.de/gitweb/?a=blobdiff_plain;f=include%2Fdns.h;h=ea02f03bb46ff83d906267b0f46e4bf20372c4b2;hb=a1f073f66f4b985bf776b9be2015136209c0c311;hp=9a93a9da74b6b556b93d67037ed97986ad5faa8f;hpb=ade5e948783377dfb7820f8ba8957fe9ae0e3147;p=user%2Fhenk%2Fcode%2Finspircd.git diff --git a/include/dns.h b/include/dns.h index 9a93a9da7..ea02f03bb 100644 --- a/include/dns.h +++ b/include/dns.h @@ -18,24 +18,45 @@ 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 "socket.h" +#include "base.h" -struct dns_ip4list { +struct dns_ip4list +{ in_addr ip; dns_ip4list *next; }; -class DNS +/** + * 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 +}; + + +/** 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. + */ +class DNS : public Extensible { private: - char *result; in_addr *binip; - int t,i; + char* result; + char localbuf[1024]; + int t; void dns_init(); - unsigned int fd; + 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); @@ -50,13 +71,160 @@ private: 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(); - DNS(std::string dnsserver); + /** 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(); - bool ReverseLookup(std::string ip); - bool ForwardLookup(std::string host); + /** 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); +}; + +/** + * 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 + * 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 Resolver : public Extensible +{ + private: + /** + * The lowlevel DNS object used by Resolver + */ + DNS Query; + /** + * The input data, either a host or an IP address + */ + std::string input; + /** + * True if a forward lookup is being performed, false if otherwise + */ + bool fwd; + /** + * 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 + */ + int fd; + /** + * The output data, e.g. a hostname or an IP. + */ + std::string result; + 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 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. + * @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. + */ + Resolver(const std::string &source, bool forward, const std::string &dnsserver); + /** + * 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); + /** + * 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. + */ + 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(); + /** + * Returns the file descriptor 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. + */ + int GetFd(); }; +/** + * Clear the pointer table used for Resolver classes + */ +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); + +void dns_close(int fd); + +#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 + #endif