Benjamin Risher <brisher...@gmail.com> writes: > Hello all, > > I'm working on a project to learn asyncio and network programming. What I'm > trying to do is forward a connection from myself to another machine. Kind of > like an asynchronous python implementation of fpipe. > > In a nutshell: > > 1 --> start a server listening on localhost > 2 --> connect to server > 3 --> server connects to a listening service (ssh for instance) > 4 --> server handles both connections to pass traffic back and forth through > each > > What I have now *kind of* works. It sends data back and forth, but when I > ssh to localhost -p 12345, i never get the password prompt. It looks like > one packet hangs out and doesn't get sent from what I saw in tcpdump. > > Any help would be greatly appreciated.
Do you want to emulate `ssh -L 12345:localhost:22 <host>`? > Here's a link to the same code as below, just with syntax highlighting etc... > http://pastebin.com/iLE4GZH3 There are several issue e.g., unnecessary async(), deprecated Task() calls but the main issue is that _handle_client() doesn't read concurrently from the server while client writes to it. You could use asyncio.wait() to run several tasks in parallel [1]. Here's a forward-port.py example [2]: #!/usr/bin/env python3 """Forward a local tcp port to host:port. Usage: %(prog)s local_port:host:port Example: $ python3 forward-port.py 26992:icanhazip.com:80 # start server and in another window: $ curl localhost:26992 # connect to it """ import asyncio import logging import sys info = logging.getLogger('forward-port').info @asyncio.coroutine def copy_stream(reader, writer, bufsize=1<<16): while True: data = yield from reader.read(bufsize) if not data: break writer.write(data) yield from writer.drain() writer.close() def port_forwarder(host, port, *, loop): @asyncio.coroutine def forward(local_reader, local_writer): client = local_writer.get_extra_info('peername') info('connected client %s %s', *client) remote_reader, remote_writer = yield from asyncio.open_connection(host, port, loop=loop) yield from asyncio.wait([copy_stream(local_reader, remote_writer), copy_stream(remote_reader, local_writer)], loop=loop) info('disconnected client %s %s', *client) return forward # main logging.basicConfig(level=logging.INFO, format="%(asctime)-15s %(message)s", datefmt="%F %T") if len(sys.argv) != 2: sys.exit(__doc__) local_port, host, port = sys.argv[1].split(':') # e.g., 12345:localhost:22 loop = asyncio.get_event_loop() server = loop.run_until_complete(asyncio.start_server(port_forwarder(host, int(port), loop=loop), 'localhost', int(local_port), loop=loop)) info('listening on: %s %s', *server.sockets[0].getsockname()) for closing in range(2): try: loop.run_until_complete(server.wait_closed()) except KeyboardInterrupt: if not closing: server.close() info('closing server') else: break info('done') loop.close() [1] https://docs.python.org/3/library/asyncio-task.html#example-parallel-execution-of-tasks [2] http://pastebin.com/g08YaJyz -- Akira -- https://mail.python.org/mailman/listinfo/python-list
