X-Git-Url: https://gerrit.fd.io/r/gitweb?p=csit.git;a=blobdiff_plain;f=GPL%2Ftraffic_scripts%2FPacketVerifier.py;h=89b8c3c2068ed4a3bd0d9e74c512c7839c6d79ae;hp=20e9af603bcd433bb3e3d0ce2ba4781868deb01f;hb=8b25b4e89bdba964f2a3d602b8c47f551a084724;hpb=79f5ba9bf7656972dd988508eff9465562dde42c

diff --git a/GPL/traffic_scripts/PacketVerifier.py b/GPL/traffic_scripts/PacketVerifier.py
index 20e9af603b..89b8c3c206 100644
--- a/GPL/traffic_scripts/PacketVerifier.py
+++ b/GPL/traffic_scripts/PacketVerifier.py
@@ -1,9 +1,19 @@
-# 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,
@@ -71,7 +81,7 @@ 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
@@ -208,7 +218,11 @@ class RxQueue(PacketVerifier):
 
         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.
@@ -220,16 +234,19 @@ class RxQueue(PacketVerifier):
         :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)}")
@@ -240,8 +257,8 @@ class RxQueue(PacketVerifier):
                     # 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
@@ -314,10 +331,15 @@ def create_gratuitous_arp_request(src_mac, src_ip):
 
 
 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