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, 39 insertions, 25 deletions

diff --git a/resources/traffic_scripts/icmpv6_echo.py b/resources/traffic_scripts/icmpv6_echo.py
index 4bf573a1f1..a18896b07f 100755
--- a/resources/traffic_scripts/icmpv6_echo.py
+++ b/resources/traffic_scripts/icmpv6_echo.py
@@ -17,13 +17,19 @@
 
 import sys
 import logging
+
+# 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():
@@ -43,52 +49,60 @@ def main():
 
     # send ICMPv6 neighbor advertisement message
     pkt_send = (Ether(src=src_mac, dst='ff:ff:ff:ff:ff:ff') /
-                        IPv6(src=src_ip, dst='ff02::1:ff00:2') /
-                        ICMPv6ND_NA(tgt=src_ip, R=0) /
-                        ICMPv6NDOptDstLLAddr(lladdr=src_mac))
+                IPv6(src=src_ip, dst='ff02::1:ff00:2') /
+                ICMPv6ND_NA(tgt=src_ip, R=0) /
+                ICMPv6NDOptDstLLAddr(lladdr=src_mac))
     sent_packets.append(pkt_send)
     txq.send(pkt_send)
 
     # send ICMPv6 echo request
     pkt_send = (Ether(src=src_mac, dst=dst_mac) /
-                        IPv6(src=src_ip, dst=dst_ip) /
-                        ICMPv6EchoRequest(id=echo_id, seq=echo_seq))
+                IPv6(src=src_ip, dst=dst_ip) /
+                ICMPv6EchoRequest(id=echo_id, seq=echo_seq))
     sent_packets.append(pkt_send)
     txq.send(pkt_send)
 
     # receive ICMPv6 echo reply
-    ether = rxq.recv(2, sent_packets)
-    if ether is None:
-        raise RuntimeError('ICMPv6 echo reply Rx timeout')
+    while True:
+        ether = rxq.recv(2, sent_packets)
+        if ether is None:
+            raise RuntimeError('ICMPv6 echo reply Rx timeout')
+
+        if ether.haslayer(ICMPv6ND_NS):
+            # read another packet in the queue if the current one is ICMPv6ND_NS
+            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 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 '
+                           'received {0}'.format(ipv6.__repr__()))
 
-    icmpv6 = ipv6['ICMPv6 Echo Reply']
+    icmpv6 = ipv6[ICMPv6EchoReply]
 
     # check identifier and sequence number
     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}'.format(icmpv6.id, icmpv6.seq, echo_id, echo_seq))
+        raise RuntimeError('Invalid ICMPv6 echo reply received ID {0} seq {1} '
+                           'should be ID {2} seq {3}'.
+                           format(icmpv6.id, icmpv6.seq, echo_id, echo_seq))
 
     # verify checksum
     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))
 
     sys.exit(0)
 
+
 if __name__ == "__main__":
     main()