+ protected:
+ /**
+ * Pointer to creator
+ */
+ 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;
+
+ /**
+ * Cached result, if there is one
+ */
+ CachedQuery *CQ;
+
+ /**
+ * Time left before cache expiry
+ */
+ 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. 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.
+ * @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.
+ */
+ Resolver(InspIRCd* Instance, const std::string &source, QueryType qt, bool &cached, 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.
+ * @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.
+ * @param resultnum Result number, for records with multiple matching results.
+ * Normally, you will only want to act on this when the result is 0.
+ */
+ virtual void OnLookupComplete(const std::string &result, unsigned int ttl, bool cached, int resultnum = 0) = 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();
+
+ /**
+ * 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();
+};
+
+/** 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:
+
+ /**
+ * Creator/Owner object
+ */
+ InspIRCd* ServerInstance;
+
+ /**
+ * The maximum value of a dns request id,
+ * 16 bits wide, 0xFFFF.
+ */
+ static const int MAX_REQUEST_ID = 0xFFFF;
+
+ /**
+ * 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;
+
+ /**
+ * 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:
+
+ /**
+ * Server address being used currently
+ */
+ int socketfamily;
+
+#ifdef IPV6
+ /**
+ * IPV6 server address
+ */
+ in6_addr myserver6;
+#endif
+ /**
+ * IPV4 server address
+ */
+ in_addr myserver4;
+
+ /**
+ * Currently active Resolver classes
+ */
+ Resolver* Classes[MAX_REQUEST_ID];
+
+ /**
+ * 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 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 irc::sockets::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
+ */
+ int GetCName(const char* alias);
+
+ /**
+ * Fetch the result string (an ip or host)
+ * and/or an error message to go with it.
+ * @param resultnum Result number to fetch
+ */
+ DNSResult GetResult(int resultnum);
+
+ /**
+ * 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(InspIRCd* Instance);
+
+ /**
+ * Re-initialize the DNS subsystem.
+ */
+ void Rehash();
+
+ /**
+ * Destructor