test.py

import re
from scapy.all import *

def psize(packet):
  #assume 20 from http://stackoverflow.com/questions/6639799/calculate-size-and-start-of-tcp-packet-data-excluding-header
  return packet[IP].len-packet[IP].ihl*4-4*packet[TCP].dataofs
def groupPacketsByFlow(packets):
  flows={}
  print flows
  print type(packets)
  for i in xrange(len(packets)):
    packet=packets[i]    
    print packet
    print type(packet)
    print packet[IP]
    return
    pair = (packet[IP].src, packets[IP].dst)
    print pair
    if  pair in flows:
      print "in if"
      flows[(packet[IP].src, packets[IP].dst)].append(packet)
    else:
      flows[(packet[IP].src, packets[IP].dst)] = [packet]
  return flows

def analyzePcap(pcap):
  packets=rdpcap(pcap)
  print len(packets)
  tcp_packets=filter(lambda p:p.haslayer(TCP),packets)
  print len(tcp_packets)
  flows = groupPacketsByFlow(tcp_packets)



if __name__=="__main__":
  analyzePcap('proper.pcap')