1 # Copyright (c) 2016 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"
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'
68 import interruptingcow
69 from scapy.config import conf
70 from scapy.all import ETH_P_IP, ETH_P_IPV6, ETH_P_ALL, ETH_P_ARP
71 from scapy.layers.inet6 import IPv6
72 from scapy.layers.l2 import Ether, ARP
74 # Enable libpcap's L2listen
76 import scapy.arch.pcapdnet # pylint: disable=C0413, unused-import
78 __all__ = ['RxQueue', 'TxQueue', 'Interface', 'create_gratuitous_arp_request',
79 'auto_pad', 'checksum_equal']
81 # TODO: http://stackoverflow.com/questions/320232/
82 # ensuring-subprocesses-are-dead-on-exiting-python-program
85 class PacketVerifier(object):
86 """Base class for TX and RX queue objects for packet verifier."""
87 def __init__(self, interface_name):
88 os.system('sudo echo 1 > /proc/sys/net/ipv6/conf/{0}/disable_ipv6'
89 .format(interface_name))
90 os.system('sudo ip link set {0} up promisc on'.format(interface_name))
91 self._ifname = interface_name
94 def extract_one_packet(buf):
95 """Extract one packet from the incoming buf buffer.
97 Takes string as input and looks for first whole packet in it.
98 If it finds one, it returns substring from the buf parameter.
100 :param buf: String representation of incoming packet buffer.
102 :returns: String representation of first packet in buf.
111 ether_type = Ether(buf[0:14]).type
112 except AttributeError:
114 'No EtherType in packet {0}'.format(buf.__repr__()))
116 if ether_type == ETH_P_IP:
117 # 14 is Ethernet fame header size.
118 # 4 bytes is just enough to look for length in ip header.
119 # ip total length contains just the IP packet length so add the Ether
121 pkt_len = Ether(buf[0:14+4]).len + 14
124 elif ether_type == ETH_P_IPV6:
125 if not Ether(buf[0:14+6]).haslayer(IPv6):
127 'Invalid IPv6 packet {0}'.format(buf.__repr__()))
128 # ... to add to the above, 40 bytes is the length of IPV6 header.
129 # The ipv6.len only contains length of the payload and not the header
130 pkt_len = Ether(buf)['IPv6'].plen + 14 + 40
133 elif ether_type == ETH_P_ARP:
134 pkt = Ether(buf[:20])
135 if not pkt.haslayer(ARP):
136 raise RuntimeError('Incomplete ARP packet')
137 # len(eth) + arp(2 hw addr type + 2 proto addr type
138 # + 1b len + 1b len + 2b operation)
141 pkt_len += 2 * pkt.getlayer(ARP).hwlen
142 pkt_len += 2 * pkt.getlayer(ARP).plen
145 elif ether_type == 32821: # RARP (Reverse ARP)
146 pkt = Ether(buf[:20])
147 pkt.type = ETH_P_ARP # Change to ARP so it works with scapy
148 pkt = Ether(str(pkt))
149 if not pkt.haslayer(ARP):
151 raise RuntimeError('Incomplete RARP packet')
153 # len(eth) + arp(2 hw addr type + 2 proto addr type
154 # + 1b len + 1b len + 2b operation)
156 pkt_len += 2 * pkt.getlayer(ARP).hwlen
157 pkt_len += 2 * pkt.getlayer(ARP).plen
161 raise RuntimeError('Unknown protocol {0}'.format(ether_type))
166 if len(buf) < pkt_len:
169 return buf[0:pkt_len]
172 def packet_reader(interface_name, queue):
173 """Sub-process routine that reads packets and puts them to queue.
175 This function is meant to be run in separate subprocess and is in tight
176 loop reading raw packets from interface passed as parameter.
178 :param interface_name: Name of interface to read packets from.
179 :param queue: Queue in which this function will push incoming packets.
180 :type interface_name: str
181 :type queue: multiprocessing.Queue
184 sock = conf.L2listen(iface=interface_name, type=ETH_P_ALL)
187 pkt = sock.recv(0x7fff)
191 class RxQueue(PacketVerifier):
192 """Receive queue object.
194 This object creates raw socket, reads packets from it and provides
195 function to access them.
197 :param interface_name: Which interface to bind to.
198 :type interface_name: str
200 def __init__(self, interface_name):
201 PacketVerifier.__init__(self, interface_name)
202 self._sock = conf.L2listen(iface=interface_name, type=ETH_P_ALL)
204 def recv(self, timeout=3, ignore=None, verbose=True):
205 """Read next received packet.
207 Returns scapy's Ether() object created from next packet in the queue.
208 Queue is being filled in parallel in subprocess. If no packet
209 arrives in given timeout queue.Empty exception will be risen.
211 :param timeout: How many seconds to wait for next packet.
212 :param ignore: List of packets that should be ignored.
213 :param verbose: Used to suppress detailed logging of received packets.
218 :returns: Ether() initialized object from packet data.
221 (rlist, _, _) = select.select([self._sock], [], [], timeout)
222 if self._sock not in rlist:
225 with interruptingcow.timeout(timeout,
226 exception=RuntimeError('Timeout')):
228 if ignore is not None:
229 for ig_pkt in ignore:
230 # Auto pad all packets in ignore list
231 ignore_list.append(auto_pad(ig_pkt))
233 pkt = self._sock.recv(0x7fff)
234 pkt_pad = auto_pad(pkt)
235 print 'Received packet on {0} of len {1}'\
236 .format(self._ifname, len(pkt))
238 pkt.show2() # pylint: disable=no-member
240 if pkt_pad in ignore_list:
241 ignore_list.remove(pkt_pad)
242 print 'Received packet ignored.'
250 class TxQueue(PacketVerifier):
251 """Transmission queue object.
253 This object is used to send packets over RAW socket on a interface.
255 :param interface_name: Which interface to send packets from.
256 :type interface_name: str
258 def __init__(self, interface_name):
259 PacketVerifier.__init__(self, interface_name)
260 self._sock = conf.L2socket(iface=interface_name, type=ETH_P_ALL)
262 def send(self, pkt, verbose=True):
263 """Send packet out of the bound interface.
265 :param pkt: Packet to send.
266 :param verbose: Used to supress detailed logging of sent packets.
267 :type pkt: string or scapy Packet derivative.
270 print 'Sending packet out of {0} of len {1}'.format(self._ifname,
273 Ether(str(pkt)).show2()
276 pkt = auto_pad(str(pkt))
280 class Interface(object):
281 """Class for network interfaces. Contains methods for sending and receiving
283 def __init__(self, if_name):
284 """Initialize the interface class.
286 :param if_name: Name of the interface.
289 self.if_name = if_name
290 self.sent_packets = []
291 self.rxq = RxQueue(if_name)
292 self.txq = TxQueue(if_name)
294 def send_pkt(self, pkt):
295 """Send the provided packet out the interface."""
296 self.sent_packets.append(pkt)
299 def recv_pkt(self, timeout=3):
300 """Read one packet from the interface's receive queue.
302 :param timeout: Timeout value in seconds.
304 :returns: Ether() initialized object from packet data.
307 return self.rxq.recv(timeout, self.sent_packets)
310 def create_gratuitous_arp_request(src_mac, src_ip):
311 """Creates scapy representation of gratuitous ARP request."""
312 return (Ether(src=src_mac, dst='ff:ff:ff:ff:ff:ff') /
313 ARP(psrc=src_ip, hwsrc=src_mac, pdst=src_ip))
316 def auto_pad(packet):
317 """Pads zeroes at the end of the packet if the total len < 60 bytes."""
320 padded += ('\0' * (60 - len(padded)))
324 def checksum_equal(chksum1, chksum2):
325 """Compares two checksums in one's complement notation.
327 Checksums to be compared are calculated as 16 bit one's complement of the
328 one's complement sum of 16 bit words of some buffer.
329 In one's complement notation 0x0000 (positive zero) and 0xFFFF
330 (negative zero) are equivalent.
332 :param chksum1: First checksum.
333 :param chksum2: Second checksum.
334 :type chksum1: uint16
335 :type chksum2: uint16
337 :returns: True if checksums are equivalent, False otherwise.
340 if chksum1 == 0xFFFF:
342 if chksum2 == 0xFFFF:
344 return chksum1 == chksum2