'Called by L{DNSServerFactory.messageReceived} when a query message is
received.
Takes the first query from the received message and dispatches it to
C{self.resolver.query}.
Adds callbacks L{DNSServerFactory.gotResolverResponse} and
L{DNSServerFactory.gotResolverError} to the resulting deferred.
Note: Multiple queries in a single message are not supported because
there is no standard way to respond with multiple rCodes, auth,
etc. This is consistent with other DNS server implementations. See
U{http://tools.ietf.org/html/draft-ietf-dnsext-edns1-03} for a proposed
solution.
@param protocol: The DNS protocol instance to which to send a response
message.
@type protocol: L{dns.DNSDatagramProtocol} or L{dns.DNSProtocol}
@param message: The original DNS query message for which a response
message will be constructed.
@type message: L{dns.Message}
@param address: The address to which the response message will be sent
or L{None} if C{protocol} is a stream protocol.
@type address: L{tuple} or L{None}
@return: A C{deferred} which fires with the resolved result or error of
the first query in C{message}.
@rtype: L{Deferred<twisted.internet.defer.Deferred>}'

def handleQuery(self, message, protocol, address):

    query = message.queries[0]
    return self.resolver.query(query).addCallback(self.gotResolverResponse, protocol, message, address).addErrback(self.gotResolverError, protocol, message, address)
