Ignore unexpected ICMPv6 Neighbor Discovery - Neighbor Solicitation packets

We need to adapt all functional traffic scripts related to functional
IPv6 tests to ingore receiving of unexpected ICMPv6ND_NS
(ICMPv6 Neighbor Discovery - Neighbor Solicitation) packets that are
sent automatically and we cannot avoid to receive them.

The reason is to prevent false negative test results in case of csit
functional tests that could block creation of new operational branch
(csit weekly jobs), usage of new vpp builds (csit semiweekly jobs)
and merging patches - csit as well as vpp.

Change-Id: I43c90e7c766762fa769a81661338759a11b401a1
Signed-off-by: Jan Gelety <jgelety@cisco.com>

1 files changed, 34 insertions, 23 deletions

diff --git a/resources/traffic_scripts/ipv6_sweep_ping.py b/resources/traffic_scripts/ipv6_sweep_ping.py
index 80fdda532a..28d23a16ef 100755
--- a/resources/traffic_scripts/ipv6_sweep_ping.py
+++ b/resources/traffic_scripts/ipv6_sweep_ping.py
@@ -19,13 +19,18 @@ import logging
 import os
 import sys
 
+# pylint: disable=no-name-in-module
+# pylint: disable=import-error
 logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
-from resources.libraries.python.PacketVerifier import RxQueue, TxQueue, \
-    checksum_equal
-from resources.libraries.python.TrafficScriptArg import TrafficScriptArg
-from scapy.layers.inet6 import IPv6, ICMPv6ND_NA, ICMPv6NDOptDstLLAddr
-from scapy.layers.inet6 import ICMPv6EchoRequest, ICMPv6EchoReply
+
 from scapy.all import Ether
+from scapy.layers.inet6 import IPv6, ICMPv6ND_NA, ICMPv6ND_NS
+from scapy.layers.inet6 import ICMPv6NDOptDstLLAddr
+from scapy.layers.inet6 import ICMPv6EchoRequest, ICMPv6EchoReply
+
+from resources.libraries.python.PacketVerifier import RxQueue, TxQueue
+from resources.libraries.python.PacketVerifier import checksum_equal
+from resources.libraries.python.TrafficScriptArg import TrafficScriptArg
 
 
 def main():
@@ -68,37 +73,43 @@ def main():
         sent_packets.append(pkt_send)
         txq.send(pkt_send)
 
-        ether = rxq.recv(ignore=sent_packets)
-        if ether is None:
-            raise RuntimeError(
-                'ICMPv6 echo reply seq {0} Rx timeout'.format(echo_seq))
+        while True:
+            ether = rxq.recv(ignore=sent_packets)
+            if ether is None:
+                raise RuntimeError('ICMPv6 echo reply seq {0} '
+                                   'Rx timeout'.format(echo_seq))
+
+            if ether.haslayer(ICMPv6ND_NS):
+                # read another packet in the queue in case of ICMPv6ND_NS packet
+                continue
+            else:
+                # otherwise process the current packet
+                break
 
         if not ether.haslayer(IPv6):
-            raise RuntimeError(
-                'Unexpected packet with no IPv6 received {0}'.format(
-                    ether.__repr__()))
+            raise RuntimeError('Unexpected packet with no IPv6 layer '
+                               'received: {0}'.format(ether.__repr__()))
 
-        ipv6 = ether['IPv6']
+        ipv6 = ether[IPv6]
 
         if not ipv6.haslayer(ICMPv6EchoReply):
-            raise RuntimeError(
-                'Unexpected packet with no IPv6 ICMP received {0}'.format(
-                    ipv6.__repr__()))
+            raise RuntimeError('Unexpected packet with no ICMPv6 echo reply '
+                               'layer received: {0}'.format(ipv6.__repr__()))
 
-        icmpv6 = ipv6['ICMPv6 Echo Reply']
+        icmpv6 = ipv6[ICMPv6EchoReply]
 
         if icmpv6.id != echo_id or icmpv6.seq != echo_seq:
-            raise RuntimeError(
-                'Invalid ICMPv6 echo reply received ID {0} seq {1} should be '
-                'ID {2} seq {3}, {0}'.format(icmpv6.id, icmpv6.seq, echo_id,
-                                             echo_seq))
+            raise RuntimeError('ICMPv6 echo reply with invalid data received: '
+                               'ID {0} seq {1} should be ID {2} seq {3}, {0}'.
+                               format(icmpv6.id, icmpv6.seq, echo_id,
+                                      echo_seq))
 
         cksum = icmpv6.cksum
         del icmpv6.cksum
         tmp = ICMPv6EchoReply(str(icmpv6))
         if not checksum_equal(tmp.cksum, cksum):
-            raise RuntimeError(
-                'Invalid checksum {0} should be {1}'.format(cksum, tmp.cksum))
+            raise RuntimeError('Invalid checksum: {0} should be {1}'.
+                               format(cksum, tmp.cksum))
 
         sent_packets.remove(pkt_send)