-# Copyright (c) 2020 Cisco and/or its affiliates.
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at:
+# Copyright (c) 2021 Cisco and/or its affiliates.
+#
+# SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+#
+# Licensed under the Apache License 2.0 or
+# GNU General Public License v2.0 or later; you may not use this file
+# except in compliance with one of these Licenses. You
+# may obtain a copy of the Licenses at:
#
# http://www.apache.org/licenses/LICENSE-2.0
+# https://www.gnu.org/licenses/old-licenses/gpl-2.0-standalone.html
+#
+# Note: If this file is linked with Scapy, which is GPLv2+, your use of it
+# must be under GPLv2+. If at any point in the future it is no longer linked
+# with Scapy (or other GPLv2+ licensed software), you are free to choose
+# Apache 2.
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
import os
import select
+import time
from scapy.all import ETH_P_IP, ETH_P_IPV6, ETH_P_ALL, ETH_P_ARP
from scapy.config import conf
from scapy.layers.inet6 import IPv6
from scapy.layers.l2 import Ether, ARP
-from scapy.packet import Raw
+from scapy.packet import Raw, Padding
# Enable libpcap's L2listen
conf.use_pcap = True
Returns scapy's Ether() object created from next packet in the queue.
Queue is being filled in parallel in subprocess. If no packet
- arrives in given timeout queue.Empty exception will be risen.
+ arrives in given timeout None is returned.
+
+ If the list of packets to ignore is given, they are logged
+ but otherwise ignored upon arrival, not adding to the timeout.
+ Each time a packet is ignored, it is removed from the ignored list.
:param timeout: How many seconds to wait for next packet.
:param ignore: List of packets that should be ignored.
:returns: Ether() initialized object from packet data.
:rtype: scapy.Ether
"""
- ignore_list = list()
- if ignore is not None:
- for ig_pkt in ignore:
- # Auto pad all packets in ignore list
- ignore_list.append(str(auto_pad(ig_pkt)))
- while True:
- rlist, _, _ = select.select([self._sock], [], [], timeout)
- if self._sock not in rlist:
+ time_end = time.monotonic() + timeout
+ ignore = ignore if ignore else list()
+ # Auto pad all packets in ignore list
+ ignore = [str(auto_pad(ig_pkt)) for ig_pkt in ignore]
+ while 1:
+ time_now = time.monotonic()
+ if time_now >= time_end:
return None
-
+ timedelta = time_end - time_now
+ rlist, _, _ = select.select([self._sock], [], [], timedelta)
+ if self._sock not in rlist:
+ # Might have been an interrupt.
+ continue
pkt = self._sock.recv(0x7fff)
pkt_pad = str(auto_pad(pkt))
print(f"Received packet on {self._ifname} of len {len(pkt)}")
# Never happens in practice, but Pylint does not know that.
print(f"Unexpected instance: {pkt!r}")
print()
- if pkt_pad in ignore_list:
- ignore_list.remove(pkt_pad)
+ if pkt_pad in ignore:
+ ignore.remove(pkt_pad)
print(u"Received packet ignored.")
continue
return pkt
def auto_pad(packet):
- """Pads zeroes at the end of the packet if the total len < 60 bytes."""
- # padded = str(packet)
- if len(packet) < 60:
- packet[Raw].load += (b"\0" * (60 - len(packet)))
+ """Pads zeroes at the end of the packet if the total packet length is less
+ then 60 bytes in case of IPv4 or 78 bytes in case of IPv6.
+ """
+ # TODO: add document explaining deduction of FCS part
+ min_len = 78 if packet.haslayer(IPv6) else 60
+ pad_layer = Raw if packet.haslayer(Raw) \
+ else Padding if packet.haslayer(Padding) else None
+ if pad_layer:
+ packet[pad_layer].load += (b"\0" * (min_len - len(packet)))
return packet