asyncio_proxy.py

import asyncio


@asyncio.coroutine
def proxify(reader, writer):
    addr_writer = writer.get_extra_info('peername')[0]

    while True:
        data = yield from reader.read(8192)

        if not data:
            print('Close connection with {}'.format(addr_writer))
            writer.close()
            break

        writer.write(data)
        yield from w.drain()


@asyncio.coroutine
def handle_client(client_reader, client_writer):
    print('A new connection')

    server_reader, server_writer = yield from asyncio.open_connection(
        '123.456.789.123', 443
    )

    asyncio.async(proxify(client_reader, server_writer))
    asyncio.async(proxify(server_reader, client_writer))


def main():
    loop = asyncio.get_event_loop()
    coro = asyncio.start_server(handle_client, '127.0.0.1', 443)
    server = loop.run_until_complete(coro)

    print('Serving on {}'.format(server.sockets[0].getsockname()))

    try:
        loop.run_forever()
    except KeyboardInterrupt:
        pass

    server.close()
    loop.run_until_complete(server.wait_closed())
    loop.close()

if __name__ == '__main__':
    main()