lossy socket for python allows you to tune how many packets are dropped

lossysocket.py

# This class wraps socket, and will maybe send your packet
# tune tx_drop_rate and rx_drop_rate, 0 means transmit everything, 1 means drop everything
# This class works best for UDP, as it doesn't allow you to drop TCP control messages

import socket
import random

class LossySocket(object):
    def __init__(self, *p):
        self._sock = socket.socket(*p)
        self.tx_drop_rate = 0.0  # percentage of outgoing packets to drop in [0,1]
        self.rx_drop_rate = 0.0  # percentage of incoming packets to drop in [0,1]
        self.verbose = True
        if self.verbose: print "LossySocket init"

    def __getattr__(self, name):
        if self.verbose: print "Getattr", name
        return getattr(self._sock, name)

    def sendall(self, *p):
        if self.verbose: print "LossySocket sendall"
        return self._sock.sendall(*p)

    def send(self, *p):
        if self.verbose: print "LossySocket send"
        return self._sock.send(*p)

    def recv(self, *p):
        if self.verbose: print "LossySocket recv"
        ret = self._sock.recv(*p)
        if random.random() < self.rx_drop_rate:
            if self.verbose: print "LossySocket dropping RX"
            raise socket.error(11, 'Intentionally dropped packet')
        return ret

    def sendto(self, *p):
        if self.verbose: print "LossySocket sendto"
        if random.random() < self.tx_drop_rate:
            if self.verbose: print "LossySocket dropping TX"
            ret = len(p[0])  # drop packet
        else:
            ret = self._sock.sendto(*p)  # send packet
        return ret

    def connect(self, *p):
        if self.verbose: print "LossySocket connecting..."
        self._sock.connect(*p)
        if self.verbose: print "LossySocket connected"