1 # Copyright (c) 2018 Cisco and/or its affiliates.
2 # Licensed under the Apache License, Version 2.0 (the "License");
3 # you may not use this file except in compliance with the License.
4 # You may obtain a copy of the License at:
6 # http://www.apache.org/licenses/LICENSE-2.0
8 # Unless required by applicable law or agreed to in writing, software
9 # distributed under the License is distributed on an "AS IS" BASIS,
10 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 # See the License for the specific language governing permissions and
12 # limitations under the License.
14 """PacketVerifier module.
18 | >>> from scapy.all import *
19 | >>> from PacketVerifier import *
20 | >>> rxq = RxQueue('eth1')
21 | >>> txq = TxQueue('eth1')
22 | >>> src_mac = "AA:BB:CC:DD:EE:FF"
23 | >>> dst_mac = "52:54:00:ca:5d:0b"
24 | >>> src_ip = "11.11.11.10"
25 | >>> dst_ip = "11.11.11.11"
26 | >>> sent_packets = []
27 | >>> pkt_send = Ether(src=src_mac, dst=dst_mac) /
28 | ... IP(src=src_ip, dst=dst_ip) /
30 | >>> sent_packets.append(pkt_send)
31 | >>> txq.send(pkt_send)
32 | >>> pkt_send = Ether(src=src_mac, dst=dst_mac) /
33 | ... ARP(hwsrc=src_mac, psrc=src_ip, hwdst=dst_mac, pdst=dst_ip, op=2)
34 | >>> sent_packets.append(pkt_send)
35 | >>> txq.send(pkt_send)
36 | >>> rxq.recv(100, sent_packets).show()
38 | dst = aa:bb:cc:dd:ee:ff
39 | src = 52:54:00:ca:5d:0b
62 | load = 'RT\x00\xca]\x0b\xaa\xbb\xcc\xdd\xee\xff\x08\x06\x00\x01\x08\x00'
70 from scapy.config import conf
71 from scapy.all import ETH_P_IP, ETH_P_IPV6, ETH_P_ALL, ETH_P_ARP
72 from scapy.layers.inet6 import IPv6
73 from scapy.layers.l2 import Ether, ARP
75 # Enable libpcap's L2listen
77 import scapy.arch.pcapdnet # pylint: disable=C0413, unused-import
79 __all__ = ['RxQueue', 'TxQueue', 'Interface', 'create_gratuitous_arp_request',
80 'auto_pad', 'checksum_equal']
82 # TODO: http://stackoverflow.com/questions/320232/
83 # ensuring-subprocesses-are-dead-on-exiting-python-program
86 class PacketVerifier(object):
87 """Base class for TX and RX queue objects for packet verifier."""
88 def __init__(self, interface_name):
89 os.system('sudo echo 1 > /proc/sys/net/ipv6/conf/{0}/disable_ipv6'
90 .format(interface_name))
91 os.system('sudo ip link set {0} up promisc on'.format(interface_name))
92 self._ifname = interface_name
95 def extract_one_packet(buf):
96 """Extract one packet from the incoming buf buffer.
98 Takes string as input and looks for first whole packet in it.
99 If it finds one, it returns substring from the buf parameter.
101 :param buf: String representation of incoming packet buffer.
103 :returns: String representation of first packet in buf.
112 ether_type = Ether(buf[0:14]).type
113 except AttributeError:
115 'No EtherType in packet {0}'.format(buf.__repr__()))
117 if ether_type == ETH_P_IP:
118 # 14 is Ethernet fame header size.
119 # 4 bytes is just enough to look for length in ip header.
120 # ip total length contains just the IP packet length so add the Ether
122 pkt_len = Ether(buf[0:14+4]).len + 14
125 elif ether_type == ETH_P_IPV6:
126 if not Ether(buf[0:14+6]).haslayer(IPv6):
128 'Invalid IPv6 packet {0}'.format(buf.__repr__()))
129 # ... to add to the above, 40 bytes is the length of IPV6 header.
130 # The ipv6.len only contains length of the payload and not the header
131 pkt_len = Ether(buf)['IPv6'].plen + 14 + 40
134 elif ether_type == ETH_P_ARP:
135 pkt = Ether(buf[:20])
136 if not pkt.haslayer(ARP):
137 raise RuntimeError('Incomplete ARP packet')
138 # len(eth) + arp(2 hw addr type + 2 proto addr type
139 # + 1b len + 1b len + 2b operation)
142 pkt_len += 2 * pkt.getlayer(ARP).hwlen
143 pkt_len += 2 * pkt.getlayer(ARP).plen
146 elif ether_type == 32821: # RARP (Reverse ARP)
147 pkt = Ether(buf[:20])
148 pkt.type = ETH_P_ARP # Change to ARP so it works with scapy
149 pkt = Ether(str(pkt))
150 if not pkt.haslayer(ARP):
152 raise RuntimeError('Incomplete RARP packet')
154 # len(eth) + arp(2 hw addr type + 2 proto addr type
155 # + 1b len + 1b len + 2b operation)
157 pkt_len += 2 * pkt.getlayer(ARP).hwlen
158 pkt_len += 2 * pkt.getlayer(ARP).plen
162 raise RuntimeError('Unknown protocol {0}'.format(ether_type))
167 if len(buf) < pkt_len:
170 return buf[0:pkt_len]
173 def packet_reader(interface_name, queue):
174 """Sub-process routine that reads packets and puts them to queue.
176 This function is meant to be run in separate subprocess and is in tight
177 loop reading raw packets from interface passed as parameter.
179 :param interface_name: Name of interface to read packets from.
180 :param queue: Queue in which this function will push incoming packets.
181 :type interface_name: str
182 :type queue: multiprocessing.Queue
185 sock = conf.L2listen(iface=interface_name, type=ETH_P_ALL)
188 pkt = sock.recv(0x7fff)
192 class RxQueue(PacketVerifier):
193 """Receive queue object.
195 This object creates raw socket, reads packets from it and provides
196 function to access them.
198 :param interface_name: Which interface to bind to.
199 :type interface_name: str
201 def __init__(self, interface_name):
202 PacketVerifier.__init__(self, interface_name)
203 self._sock = conf.L2listen(iface=interface_name, type=ETH_P_ALL)
205 def recv(self, timeout=3, ignore=None, verbose=True):
206 """Read next received packet.
208 Returns scapy's Ether() object created from next packet in the queue.
209 Queue is being filled in parallel in subprocess. If no packet
210 arrives in given timeout queue.Empty exception will be risen.
212 :param timeout: How many seconds to wait for next packet.
213 :param ignore: List of packets that should be ignored.
214 :param verbose: Used to suppress detailed logging of received packets.
219 :returns: Ether() initialized object from packet data.
223 if ignore is not None:
224 for ig_pkt in ignore:
225 # Auto pad all packets in ignore list
226 ignore_list.append(auto_pad(ig_pkt))
228 (rlist, _, _) = select.select([self._sock], [], [], timeout)
229 if self._sock not in rlist:
232 pkt = self._sock.recv(0x7fff)
233 pkt_pad = auto_pad(pkt)
234 print 'Received packet on {0} of len {1}'\
235 .format(self._ifname, len(pkt))
237 pkt.show2() # pylint: disable=no-member
239 if pkt_pad in ignore_list:
240 ignore_list.remove(pkt_pad)
241 print 'Received packet ignored.'
247 class TxQueue(PacketVerifier):
248 """Transmission queue object.
250 This object is used to send packets over RAW socket on a interface.
252 :param interface_name: Which interface to send packets from.
253 :type interface_name: str
255 def __init__(self, interface_name):
256 PacketVerifier.__init__(self, interface_name)
257 self._sock = conf.L2socket(iface=interface_name, type=ETH_P_ALL)
259 def send(self, pkt, verbose=True):
260 """Send packet out of the bound interface.
262 :param pkt: Packet to send.
263 :param verbose: Used to supress detailed logging of sent packets.
264 :type pkt: string or scapy Packet derivative.
267 print 'Sending packet out of {0} of len {1}'.format(self._ifname,
270 Ether(str(pkt)).show2()
273 pkt = auto_pad(str(pkt))
277 class Interface(object):
278 """Class for network interfaces. Contains methods for sending and receiving
280 def __init__(self, if_name):
281 """Initialize the interface class.
283 :param if_name: Name of the interface.
286 self.if_name = if_name
287 self.sent_packets = []
288 self.rxq = RxQueue(if_name)
289 self.txq = TxQueue(if_name)
291 def send_pkt(self, pkt):
292 """Send the provided packet out the interface."""
293 self.sent_packets.append(pkt)
296 def recv_pkt(self, timeout=3):
297 """Read one packet from the interface's receive queue.
299 :param timeout: Timeout value in seconds.
301 :returns: Ether() initialized object from packet data.
304 return self.rxq.recv(timeout, self.sent_packets)
307 def create_gratuitous_arp_request(src_mac, src_ip):
308 """Creates scapy representation of gratuitous ARP request."""
309 return (Ether(src=src_mac, dst='ff:ff:ff:ff:ff:ff') /
310 ARP(psrc=src_ip, hwsrc=src_mac, pdst=src_ip))
313 def auto_pad(packet):
314 """Pads zeroes at the end of the packet if the total len < 60 bytes."""
317 padded += ('\0' * (60 - len(padded)))
321 def checksum_equal(chksum1, chksum2):
322 """Compares two checksums in one's complement notation.
324 Checksums to be compared are calculated as 16 bit one's complement of the
325 one's complement sum of 16 bit words of some buffer.
326 In one's complement notation 0x0000 (positive zero) and 0xFFFF
327 (negative zero) are equivalent.
329 :param chksum1: First checksum.
330 :param chksum2: Second checksum.
331 :type chksum1: uint16
332 :type chksum2: uint16
334 :returns: True if checksums are equivalent, False otherwise.
337 if chksum1 == 0xFFFF:
339 if chksum2 == 0xFFFF:
341 return chksum1 == chksum2