Dynamic port remote listener - a BUG?

[Przemysław Szczygielski]

Hello,

Today I tried using "dynamically assigned" port for remote listener, by
requesting listener on port 0. This is supposed to create a listener on a
port choosen by server. Everything seemed OK (the choosen port was sent back
to client), but forwarding was refused. So I checked the source.

in channels.c, function: channel_setup_fwd_listener

                /*
                 * listen_port == 0 requests a dynamically allocated port -
                 * record what we got.
                 */
                if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0
&&
                    allocated_listen_port != NULL &&
                    *allocated_listen_port == 0) {
                        *allocated_listen_port = get_sock_port(sock, 1);
                        debug("Allocated listen port %d",
                            *allocated_listen_port);
                }

                /* Allocate a channel number for the socket. */
                c = channel_new("port listener", type, sock, sock, -1,
                    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
                    0, "port listener", 1);
                c->path = xstrdup(host);
                c->host_port = port_to_connect;
                c->listening_port = listen_port;
                success = 1;
        }
        if (success == 0)
                error("channel_setup_fwd_listener: cannot listen to port:
%d",
                    listen_port);
        freeaddrinfo(aitop);
        return success;
}

As you see allocated_listen_port gets assigned to some free port, but
then... nothing more happens with allocated_listen_port, because
c->listening_port is set to listen_port, which in this case equals 0. (note
that listen_port IS NOT set to allocated_listen_port!)

But then again - I am not a programmer. So I might be wrong.