I couldn't find anything already out there so I wrote a python script to do this (this is probably buggy):
#!/usr/bin/env python26
"""Add latency to a tcp connection"""
from argparse import ArgumentParser, ArgumentDefaultsHelpFormatter
from functools import partial
from twisted.internet.reactor import (
listenTCP, connectTCP, callLater, run
)
from twisted.internet.protocol import (
ServerFactory, ReconnectingClientFactory, Protocol
)
class ConnectionToServer(Protocol):
def __init__(self, connection_from_client, delay_to_client):
self._delay_to_client = delay_to_client
self._connection_from_client = connection_from_client
def connectionMade(self):
self._connection_from_client.connection_to_server = self
if self._connection_from_client.buffer_from_client:
self.transport.write(
self._connection_from_client.buffer_from_client
)
def dataReceived(self, data):
callLater(
self._delay_to_client,
self._connection_from_client.transport.write, data
)
def connectionLost(self, reason):
callLater(
self._delay_to_client,
self._connection_from_client.transport.loseConnection
)
class ConnectionFromClient(Protocol):
def __init__(self, server_host, server_port, delay_to_client, delay_to_server):
self._delay_to_server = delay_to_server
self.connection_to_server = None
self.buffer_from_client = ''
server_connection_factory = ReconnectingClientFactory()
server_connection_factory.protocol = partial(
ConnectionToServer, self, delay_to_client
)
self._server_connector = connectTCP(
server_host, server_port, server_connection_factory
)
def dataReceived(self, data):
callLater(self._delay_to_server, self._write, data)
def connectionLost(self, reason):
callLater(
self._delay_to_server, self._server_connector.disconnect
)
def _write(self, data):
if self.connection_to_server:
self.connection_to_server.transport.write(data)
else:
self.buffer_from_client += data
def main():
"""Add latency to a tcp connection"""
parser = ArgumentParser(
description=main.__doc__,
formatter_class=ArgumentDefaultsHelpFormatter
)
parser.add_argument(
'client_port', type=int, help='client connects to this port'
)
parser.add_argument(
'server_port', type=int, help='server listens on this port'
)
parser.add_argument(
'-t', '--server-host', default='localhost',
help='server is running on this host'
)
parser.add_argument(
'-c', '--delay-to-client', default=0, type=float,
help='messages to client are delayed by this many seconds'
)
parser.add_argument(
'-s', '--delay-to-server', default=0, type=float,
help='messages to server are delayed by this many seconds'
)
args = parser.parse_args()
client_connection_factory = ServerFactory()
client_connection_factory.protocol = partial(
ConnectionFromClient, args.server_host, args.server_port,
args.delay_to_client, args.delay_to_server
)
listenTCP(args.client_port, client_connection_factory)
run()
if __name__ == '__main__':
main()