Since we're using a single UDP socket to implement multiple uTP sockets,
and since we're not always timely in servicing an incoming UDP packet,
it's important to use a large receive buffer. The send buffer is probably
less critical, we increase it nonetheless.
There's no need to test for DHT/uTP being enabled in tr-udp. The DHT
will silently discard any packets directed at the wrong session (see the
beginning of dhtCallback). As to uTP, we need to grok uTP packets
to close any remaining connections after we disabled uTP, so it's better
to participate in uTP, just reject any incoming connections.
This adds code to participate in the UTP protocol, but without doing anything
useful yet -- we just shut down immediately any incoming connexion request.
Add code to honor the ipv6 bind address. Thanks to jch for saving me a little work by confirming the bug and pointing out where in the code the change needed to be made.
Jordan Lee