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, 21 insertions, 14 deletions

diff --git a/resources/traffic_scripts/send_icmp_type_code.py b/resources/traffic_scripts/send_icmp_type_code.py
index dffaafff38..2997f91264 100755
--- a/resources/traffic_scripts/send_icmp_type_code.py
+++ b/resources/traffic_scripts/send_icmp_type_code.py
@@ -19,10 +19,9 @@ the other one. Dot1q or Dot1ad tagging of the ethernet frame can be set.
 import sys
 import ipaddress
 
-from scapy.layers.inet import ICMP, IP
 from scapy.layers.l2 import Ether
-from scapy.layers.inet6 import ICMPv6EchoRequest
-from scapy.layers.inet6 import IPv6
+from scapy.layers.inet import ICMP, IP
+from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest, ICMPv6ND_NS
 
 from resources.libraries.python.PacketVerifier import RxQueue, TxQueue
 from resources.libraries.python.TrafficScriptArg import TrafficScriptArg
@@ -88,13 +87,13 @@ def main():
         pkt_raw = (Ether(src=src_mac, dst=dst_mac) /
                    IP(src=src_ip, dst=dst_ip) /
                    ICMP(code=icmp_code, type=icmp_type))
-        ip_format = 'IP'
-        icmp_format = 'ICMP'
+        ip_format = IP
+        icmp_format = ICMP
     elif valid_ipv6(src_ip) and valid_ipv6(dst_ip):
         pkt_raw = (Ether(src=src_mac, dst=dst_mac) /
                    IPv6(src=src_ip, dst=dst_ip) /
                    ICMPv6EchoRequest(code=icmp_code, type=icmp_type))
-        ip_format = 'IPv6'
+        ip_format = IPv6
         icmp_format = 'ICMPv6'
     else:
         raise ValueError("IP(s) not in correct format")
@@ -103,23 +102,31 @@ def main():
     sent_packets.append(pkt_raw)
     txq.send(pkt_raw)
 
-    ether = rxq.recv(2)
+    while True:
+        ether = rxq.recv(2)
+        if ether is None:
+            raise RuntimeError('ICMP echo Rx timeout')
 
-    # Check whether received packet contains layers Ether, IP and ICMP
-    if ether is None:
-        raise RuntimeError('ICMP echo 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
 
+    # Check whether received packet contains layers IP and ICMP
     if not ether.haslayer(ip_format):
-        raise RuntimeError('Not an IP packet received {0}'
-                           .format(ether.__repr__()))
+        raise RuntimeError('Not an IP packet received {0}'.
+                           format(ether.__repr__()))
 
     # Cannot use haslayer for ICMPv6, every type of ICMPv6 is a separate layer
     # Next header value of 58 means the next header is ICMPv6
     if not ether.haslayer(icmp_format) and ether[ip_format].nh != 58:
-        raise RuntimeError('Not an ICMP packet received {0}'
-                           .format(ether.__repr__()))
+        raise RuntimeError('Not an ICMP packet received {0}'.
+                           format(ether.__repr__()))
 
     sys.exit(0)
 
+
 if __name__ == "__main__":
     main()