Script to read pcap files and play them back as UDP packets (meant for Velodyne testing)

pcap_reader.py

#!/usr/bin/env python

# Read a .pcap file full of UDP packets from a velodyne and play them back to
# localhost:2368, for consumption by the velodyne driver.
#
# TODO: error-checking and options (looping, etc.)

import dpkt
import sys
import socket
import time

UDP_IP = "localhost"
UDP_PORT = 2368

def parse(fname):
    lasttime = -1
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    i = 0
    with open(fname) as f:
        pcap = dpkt.pcap.Reader(f)
        for ts, buf in pcap:
            eth = dpkt.ethernet.Ethernet(buf)
            ip = eth.data
            udp = ip.data
            velodata = udp.data
            if lasttime > 0 and (ts-lasttime) > 0:
                time.sleep(ts-lasttime)
            lasttime = ts
            print('[%d] [%s] sending %d-byte message'%(i,`ts`,len(velodata)))
            sock.sendto(velodata, (UDP_IP, UDP_PORT))
            i += 1

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print('ERROR: must supply pcap filename')
        sys.exit(1)
    while True:
        parse(sys.argv[1])