Tim Gosselin <[EMAIL PROTECTED]> wrote: > I am writing a tcp tunnel but cannot find a way of detecting when a socket > shuts down its read end without writing to the socket. For testing the > write end of the remote endpoint I just do a: > > if not sock.recv(buffsize) > > I cannot write to the socket and check if send returns 0 though, because > that involves sending data out of the which may not have come in yet. > > When I try polling the socket with: > r, w, e=select([],[sock],[], 0) > w returns with the socket still writable, even if the other end was > closed.
Even at the C level, I believe there were some differences between Unix and Windows sockets in regard to this, so this advice may be dependent on your platform. At any rate, on both Unix and Windows, a closed socket will continue to report itself as writable. To detect the closed socket, I believe that one system reports the socket as being in error whereas the other system reports the socket as being readable (where read() will then immediately return 0 because the socket is closed). So in summary, instead of: r, w, e=select([],[sock],[], 0) try this: r, w, e=select([sock],[],[sock], 0) If r or e is non-empty, then the socket has been closed (or there's some other error). HTH, - Mike -- http://mail.python.org/mailman/listinfo/python-list
