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1#!/usr/bin/python
2#
3# Copyright 2015 The Android Open Source Project
4#
5# Licensed under the Apache License, Version 2.0 (the "License");
6# you may not use this file except in compliance with the License.
7# You may obtain a copy of the License at
8#
9# http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS,
13# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14# See the License for the specific language governing permissions and
15# limitations under the License.
16
17import random
18
19from scapy import all as scapy
20from socket import *
21
22import net_test
23
24TCP_FIN = 1
25TCP_SYN = 2
26TCP_RST = 4
27TCP_PSH = 8
28TCP_ACK = 16
29
30TCP_SEQ = 1692871236
31TCP_WINDOW = 14400
32
33PING_IDENT = 0xff19
34PING_PAYLOAD = "foobarbaz"
35PING_SEQ = 3
36PING_TOS = 0x83
37
38# For brevity.
39UDP_PAYLOAD = net_test.UDP_PAYLOAD
40
41
42def RandomPort():
43  return random.randint(1025, 65535)
44
45def _GetIpLayer(version):
46  return {4: scapy.IP, 6: scapy.IPv6}[version]
47
48def _SetPacketTos(packet, tos):
49  if isinstance(packet, scapy.IPv6):
50    packet.tc = tos
51  elif isinstance(packet, scapy.IP):
52    packet.tos = tos
53  else:
54    raise ValueError("Can't find ToS Field")
55
56def UDP(version, srcaddr, dstaddr, sport=0):
57  ip = _GetIpLayer(version)
58  # Can't just use "if sport" because None has meaning (it means unspecified).
59  if sport == 0:
60    sport = RandomPort()
61  return ("UDPv%d packet" % version,
62          ip(src=srcaddr, dst=dstaddr) /
63          scapy.UDP(sport=sport, dport=53) / UDP_PAYLOAD)
64
65def UDPWithOptions(version, srcaddr, dstaddr, sport=0):
66  if version == 4:
67    packet = (scapy.IP(src=srcaddr, dst=dstaddr, ttl=39, tos=0x83) /
68              scapy.UDP(sport=sport, dport=53) /
69              UDP_PAYLOAD)
70  else:
71    packet = (scapy.IPv6(src=srcaddr, dst=dstaddr,
72                         fl=0xbeef, hlim=39, tc=0x83) /
73              scapy.UDP(sport=sport, dport=53) /
74              UDP_PAYLOAD)
75  return ("UDPv%d packet with options" % version, packet)
76
77def SYN(dport, version, srcaddr, dstaddr, sport=0, seq=TCP_SEQ):
78  ip = _GetIpLayer(version)
79  if sport == 0:
80    sport = RandomPort()
81  return ("TCP SYN",
82          ip(src=srcaddr, dst=dstaddr) /
83          scapy.TCP(sport=sport, dport=dport,
84                    seq=seq, ack=0,
85                    flags=TCP_SYN, window=TCP_WINDOW))
86
87def RST(version, srcaddr, dstaddr, packet):
88  ip = _GetIpLayer(version)
89  original = packet.getlayer("TCP")
90  was_syn_or_fin = (original.flags & (TCP_SYN | TCP_FIN)) != 0
91  return ("TCP RST",
92          ip(src=srcaddr, dst=dstaddr) /
93          scapy.TCP(sport=original.dport, dport=original.sport,
94                    ack=original.seq + was_syn_or_fin, seq=None,
95                    flags=TCP_RST | TCP_ACK, window=TCP_WINDOW))
96
97def SYNACK(version, srcaddr, dstaddr, packet):
98  ip = _GetIpLayer(version)
99  original = packet.getlayer("TCP")
100  return ("TCP SYN+ACK",
101          ip(src=srcaddr, dst=dstaddr) /
102          scapy.TCP(sport=original.dport, dport=original.sport,
103                    ack=original.seq + 1, seq=None,
104                    flags=TCP_SYN | TCP_ACK, window=None))
105
106def ACK(version, srcaddr, dstaddr, packet, payload=""):
107  ip = _GetIpLayer(version)
108  original = packet.getlayer("TCP")
109  was_syn_or_fin = (original.flags & (TCP_SYN | TCP_FIN)) != 0
110  ack_delta = was_syn_or_fin + len(original.payload)
111  desc = "TCP data" if payload else "TCP ACK"
112  flags = TCP_ACK | TCP_PSH if payload else TCP_ACK
113  return (desc,
114          ip(src=srcaddr, dst=dstaddr) /
115          scapy.TCP(sport=original.dport, dport=original.sport,
116                    ack=original.seq + ack_delta, seq=original.ack,
117                    flags=flags, window=TCP_WINDOW) /
118          payload)
119
120def FIN(version, srcaddr, dstaddr, packet):
121  ip = _GetIpLayer(version)
122  original = packet.getlayer("TCP")
123  was_syn_or_fin = (original.flags & (TCP_SYN | TCP_FIN)) != 0
124  ack_delta = was_syn_or_fin + len(original.payload)
125  return ("TCP FIN",
126          ip(src=srcaddr, dst=dstaddr) /
127          scapy.TCP(sport=original.dport, dport=original.sport,
128                    ack=original.seq + ack_delta, seq=original.ack,
129                    flags=TCP_ACK | TCP_FIN, window=TCP_WINDOW))
130
131def GRE(version, srcaddr, dstaddr, proto, packet):
132  if version == 4:
133    ip = scapy.IP(src=srcaddr, dst=dstaddr, proto=net_test.IPPROTO_GRE)
134  else:
135    ip = scapy.IPv6(src=srcaddr, dst=dstaddr, nh=net_test.IPPROTO_GRE)
136  packet = ip / scapy.GRE(proto=proto) / packet
137  return ("GRE packet", packet)
138
139def ICMPPortUnreachable(version, srcaddr, dstaddr, packet):
140  if version == 4:
141    # Linux hardcodes the ToS on ICMP errors to 0xc0 or greater because of
142    # RFC 1812 4.3.2.5 (!).
143    return ("ICMPv4 port unreachable",
144            scapy.IP(src=srcaddr, dst=dstaddr, proto=1, tos=0xc0) /
145            scapy.ICMPerror(type=3, code=3) / packet)
146  else:
147    return ("ICMPv6 port unreachable",
148            scapy.IPv6(src=srcaddr, dst=dstaddr) /
149            scapy.ICMPv6DestUnreach(code=4) / packet)
150
151def ICMPPacketTooBig(version, srcaddr, dstaddr, packet):
152  if version == 4:
153    return ("ICMPv4 fragmentation needed",
154            scapy.IP(src=srcaddr, dst=dstaddr, proto=1) /
155            scapy.ICMPerror(type=3, code=4, unused=1280) / str(packet)[:64])
156  else:
157    udp = packet.getlayer("UDP")
158    udp.payload = str(udp.payload)[:1280-40-8]
159    return ("ICMPv6 Packet Too Big",
160            scapy.IPv6(src=srcaddr, dst=dstaddr) /
161            scapy.ICMPv6PacketTooBig() / str(packet)[:1232])
162
163def ICMPEcho(version, srcaddr, dstaddr):
164  ip = _GetIpLayer(version)
165  icmp = {4: scapy.ICMP, 6: scapy.ICMPv6EchoRequest}[version]
166  packet = (ip(src=srcaddr, dst=dstaddr) /
167            icmp(id=PING_IDENT, seq=PING_SEQ) / PING_PAYLOAD)
168  _SetPacketTos(packet, PING_TOS)
169  return ("ICMPv%d echo" % version, packet)
170
171def ICMPReply(version, srcaddr, dstaddr, packet):
172  ip = _GetIpLayer(version)
173  # Scapy doesn't provide an ICMP echo reply constructor.
174  icmpv4_reply = lambda **kwargs: scapy.ICMP(type=0, **kwargs)
175  icmp = {4: icmpv4_reply, 6: scapy.ICMPv6EchoReply}[version]
176  packet = (ip(src=srcaddr, dst=dstaddr) /
177            icmp(id=PING_IDENT, seq=PING_SEQ) / PING_PAYLOAD)
178  # IPv6 only started copying the tclass to echo replies in 3.14.
179  if version == 4 or net_test.LINUX_VERSION >= (3, 14):
180    _SetPacketTos(packet, PING_TOS)
181  return ("ICMPv%d echo reply" % version, packet)
182
183def NS(srcaddr, tgtaddr, srcmac):
184  solicited = inet_pton(AF_INET6, tgtaddr)
185  last3bytes = tuple([ord(b) for b in solicited[-3:]])
186  solicited = "ff02::1:ff%02x:%02x%02x" % last3bytes
187  packet = (scapy.IPv6(src=srcaddr, dst=solicited) /
188            scapy.ICMPv6ND_NS(tgt=tgtaddr) /
189            scapy.ICMPv6NDOptSrcLLAddr(lladdr=srcmac))
190  return ("ICMPv6 NS", packet)
191
192def NA(srcaddr, dstaddr, srcmac):
193  packet = (scapy.IPv6(src=srcaddr, dst=dstaddr) /
194            scapy.ICMPv6ND_NA(tgt=srcaddr, R=0, S=1, O=1) /
195            scapy.ICMPv6NDOptDstLLAddr(lladdr=srcmac))
196  return ("ICMPv6 NA", packet)
197
198