Ensure to check whether the socket at hand is indeed still connected
throughout POLLIN processing in ssh_socket_pollcallback.
Before this change, the POLLIN block in ssh_socket_pollcallback is
predicated against the condition (s->state == SSH_SOCKET_CONNECTED).
Once entered, data from the socket is consumed through the data
callback in this loop:
do {
r = s->callbacks->data(buffer_get_rest(s->in_buffer),
buffer_get_rest_len(s->in_buffer),
s->callbacks->userdata);
buffer_pass_bytes(s->in_buffer,r);
} while (r > 0);
However, it is possible for the socket data callback to change the
state of the socket (closing it, for example). Fix the loop to only
continue so long as the socket remains connected: this also entails
setting the ssh_socket state to SSH_SOCKET_CLOSED upon close.
The bug can be observed before the change by sending a bogus banner
to the server: 'echo -e "A\r\nB\r\n" | nc localhost 22'. Each of
'A' and 'B' will be processed by 'callback_receive_banner', even
though the client socket is closed after rejection of 'A'.
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
95782ada1f