Motivation:
codec-dns has great function to solve dns packet, but only make a query, not answer query from other client.
i make a change of add two classes to fill last pieces of map, finish the server function.
Modifications:
in this change, add two classes of DatagramDnsQueryDecoder and DatagramDnsResponseEncoder to handle client query, reply answer.
Result:
nothing code change after this commit, except two new classes.
b9ae48589b