diff options
| -rw-r--r-- | include/dns.h | 88 |
1 files changed, 87 insertions, 1 deletions
diff --git a/include/dns.h b/include/dns.h index 6da7d4778..c6c1d9a23 100644 --- a/include/dns.h +++ b/include/dns.h @@ -29,6 +29,9 @@ struct dns_ip4list dns_ip4list *next; }; +/** + * Error types that class Resolver can emit to its error method. + */ enum ResolverError { RESOLVER_NOERROR = 0, @@ -40,6 +43,10 @@ enum ResolverError /** 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 { @@ -109,34 +116,113 @@ public: 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 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); +#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 |