We only respond once to data, then half-close the connection.
Hence, we should only listen to a single data event as well,
else if the remote doesn't stop sending data we keep trying to
write to the closed write end of the pipe.
Per RFC 1413, The uniquely identifying tuple includes not only the ports,
but also both addresses.
If multiple connections happen to use the same local port number
(which is possible if the addresses differ), the username of the first
is returned for all, resulting in the wrong ident for all but the
first.
By not checking the connection address, the information becomes
public. Because there is only relatively small number of local ports,
and the remote ports are likely to be either 6667 or 6697, it becomes
trivial to enumerate all the users.
Co-Authored-By: Juerd Waalboer <juerd@tnx.nl>
