How to create TCP proxy server with asyncio?

Question

I found these example with TCP client and server on asyncio: tcp server example. But how to connect them to get TCP proxy server which will be receive data and send it to other adress?

Answer 1

You can combine both the TCP client and server examples from the user documentation.

You then need to connect the streams together using this kind of helper:

async def pipe(reader, writer):
    try:
        while not reader.at_eof():
            writer.write(await reader.read(2048))
    finally:
        writer.close()

Here's a possible client handler:

async def handle_client(local_reader, local_writer):
    try:
        remote_reader, remote_writer = await asyncio.open_connection(
            '127.0.0.1', 8889)
        pipe1 = pipe(local_reader, remote_writer)
        pipe2 = pipe(remote_reader, local_writer)
        await asyncio.gather(pipe1, pipe2)
    finally:
        local_writer.close()

And the server code:

# Create the server
loop = asyncio.get_event_loop()
coro = asyncio.start_server(handle_client, '127.0.0.1', 8888)
server = loop.run_until_complete(coro)

# Serve requests until Ctrl+C is pressed
print('Serving on {}'.format(server.sockets[0].getsockname()))
try:
    loop.run_forever()
except KeyboardInterrupt:
    pass

# Close the server
server.close()
loop.run_until_complete(server.wait_closed())
loop.close()