Simple UDP packet recorder and playback

udp_player.py

# Emanuele Ruffaldi 2018
import argparse,socket,socket,json,time

def str2bool(v):
    if v.lower() in ('yes', 'true', 't', 'y', '1'):
        return True
    elif v.lower() in ('no', 'false', 'f', 'n', '0'):
        return False
    else:
        raise argparse.ArgumentTypeError('Boolean value expected.')

def timedplayer(filename,timescale,loop):
    while True:
        with open(filename,"rb") as of:
            t0r = None
            t0v = None
            while True:
                x = of.readline().strip()
                if len(x) == 0:
                    break
                inc = json.loads(x)
                tvs = inc["absolutetime"]
                tr = time.time()
                if t0v is not None:
                    tv = (tr-t0r)*timescale + t0v  # virtual time
                    dtv = tvs-tv  # delta of virtual time and the stored one                
                    if dtv > 0:
                        time.sleep(dtv)
                else:
                    t0r = tr
                    t0v = tvs
                # string is unicode we encode it as latin1 8-bit
                do = inc["data"].encode("latin1")
                yield do,tr,tvs
        if args.loop:
            break


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='UDP data player')
    parser.add_argument("input",help="input file")
    parser.add_argument('--port',default=9763,type=int)
    parser.add_argument('--host',default="localhost")
    parser.add_argument('--verbose',action="store_true")
    parser.add_argument('--loop',type=str2bool, nargs='?',
                        const=True, default=True,
                        help="Activate loop mode.")
    parser.add_argument('--timescale',default=1.0,type=float,help="> 1.0 for real faster")

    args = parser.parse_args()
    sock = socket.socket(socket.AF_INET, # Internet
                     socket.SOCK_DGRAM) # UDP

    for data,realtime,virtualtime in timedplayer(args.input,args.timescale,args.loop):
        sock.sendto(data, (args.host, args.port))
        if args.verbose:
            print len(data),virtualtime


        

udp_recorder.py

#  Test Record
#  nc 127.0.0.1 9763 -u
#  python udp_recorder.py x
#  cat x

#  nc 127.0.0.1 -ul 9863
#  python udp_player.py x
# Emanuele Ruffaldi 2018
import argparse,socket,socket,json,time

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description='UDP data recorder')
    parser.add_argument("output",help="output file")
    parser.add_argument('--port',default=9763,type=int)
    parser.add_argument('--host',default="localhost")
    parser.add_argument('--source',default="",help="limit to source IP address")

    args = parser.parse_args()
    sock = socket.socket(socket.AF_INET, # Internet
                     socket.SOCK_DGRAM) # UDP
    sock.bind((args.host, args.port))

    with open(args.output,"wb") as of:
        t0 = time.time()
        while True:
            data, addr = sock.recvfrom(32768*2) # buffer size is 1024 bytes
            if args.source != "" and addr != args.source:
                continue
            abstime = time.time()
            dt = abstime-t0
            print dt,len(data),addr
            out = dict(absolutetime=abstime,reltime_seconds=dt,data=data,addr=addr)
            json.dump(out,of)
            of.write("\n")