1#!/usr/local/bin/python2.7
2# old fragment completely overlaps new one
3
4#      |------------|
5#          |XXXX|
6# |----|
7
8# If the current fragment is completely overlapped by existing ones,
9# drop the newer fragment.
10#                 if (precut >= frent->fe_len)
11#                         goto bad_fragment;
12# 'Nearer' traffic wins.
13
14import os
15import threading
16from addr import *
17from scapy.all import *
18
19class Sniff1(threading.Thread):
20	filter = None
21	captured = None
22	packet = None
23	def run(self):
24		self.captured = sniff(iface=SRC_IF, filter=self.filter,
25		    count=1, timeout=3)
26		if self.captured:
27			self.packet = self.captured[0]
28
29dstaddr=sys.argv[1]
30pid=os.getpid()
31eid=pid & 0xffff
32payload="ABCDEFGHIJKLOMNOQRSTUVWX"
33dummy="01234567"
34packet=IP(src=SRC_OUT, dst=dstaddr)/ICMP(type='echo-request', id=eid)/payload
35fid=pid & 0xffff
36frag0=str(packet)[20:28]
37frag1=dummy
38frag2=str(packet)[28:52]
39pkt0=IP(src=SRC_OUT, dst=dstaddr, proto=1, id=fid, frag=0, flags='MF')/frag0
40pkt1=IP(src=SRC_OUT, dst=dstaddr, proto=1, id=fid, frag=2, flags='MF')/frag1
41pkt2=IP(src=SRC_OUT, dst=dstaddr, proto=1, id=fid, frag=1)/frag2
42eth=[]
43eth.append(Ether(src=SRC_MAC, dst=PF_MAC)/pkt2)
44eth.append(Ether(src=SRC_MAC, dst=PF_MAC)/pkt1)
45eth.append(Ether(src=SRC_MAC, dst=PF_MAC)/pkt0)
46
47sniffer = Sniff1();
48sniffer.filter = "ip and src %s and dst %s and icmp" % (dstaddr, SRC_OUT)
49sniffer.start()
50time.sleep(1)
51sendp(eth, iface=SRC_IF)
52sniffer.join(timeout=5)
53a = sniffer.packet
54
55if a and a.type == ETH_P_IP and \
56    a.payload.proto == 1 and \
57    a.payload.frag == 0 and a.payload.flags == 0 and \
58    icmptypes[a.payload.payload.type] == 'echo-reply':
59	id=a.payload.payload.id
60	print "id=%#x" % (id)
61	if id != eid:
62		print "WRONG ECHO REPLY ID"
63		exit(2)
64	load=a.payload.payload.payload.load
65	print "payload=%s" % (load)
66	if load == payload:
67		exit(0)
68	print "PAYLOAD!=%s" % (payload)
69	exit(1)
70print "NO ECHO REPLY"
71exit(2)
72