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, 22 insertions, 12 deletions

diff --git a/resources/traffic_scripts/send_icmp_wait_for_reply.py b/resources/traffic_scripts/send_icmp_wait_for_reply.py
index a77f15efc2..7677152801 100755
--- a/resources/traffic_scripts/send_icmp_wait_for_reply.py
+++ b/resources/traffic_scripts/send_icmp_wait_for_reply.py
@@ -17,9 +17,9 @@
 import sys
 import ipaddress
 
-from scapy.layers.inet import ICMP, IP
-from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest
 from scapy.all import Ether
+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
@@ -35,14 +35,14 @@ def is_icmp_reply(pkt, ipformat):
     :type ipformat: dict
     :rtype: bool
     """
-    #pylint: disable=bare-except
+    # pylint: disable=bare-except
     try:
         if pkt[ipformat['IPType']][ipformat['ICMP_rep']].type == \
                 ipformat['Type']:
             return True
         else:
             return False
-    except:
+    except: # pylint: disable=bare-except
         return False
 
 
@@ -58,12 +58,12 @@ def address_check(request, reply, ipformat):
     :type ipformat: dict
     :rtype: bool
     """
-    #pylint: disable=bare-except
+    # pylint: disable=bare-except
     try:
         r_src = reply[ipformat['IPType']].src == request[ipformat['IPType']].dst
         r_dst = reply[ipformat['IPType']].dst == request[ipformat['IPType']].src
         return r_src and r_dst
-    except:
+    except: # pylint: disable=bare-except
         return False
 
 
@@ -139,12 +139,21 @@ def main():
     txq.send(icmp_request)
 
     for _ in range(1000):
-        icmp_reply = rxq.recv(wait_step, ignore=sent_packets)
-        if icmp_reply is None:
-            timeout -= wait_step
-            if timeout < 0:
-                raise RuntimeError("ICMP echo Rx timeout")
-        elif is_icmp_reply(icmp_reply, ip_format):
+        while True:
+            icmp_reply = rxq.recv(wait_step, ignore=sent_packets)
+            if icmp_reply is None:
+                timeout -= wait_step
+                if timeout < 0:
+                    raise RuntimeError("ICMP echo Rx timeout")
+
+            elif icmp_reply.haslayer(ICMPv6ND_NS):
+                # read another packet in the queue in case of ICMPv6ND_NS packet
+                continue
+            else:
+                # otherwise process the current packet
+                break
+
+        if is_icmp_reply(icmp_reply, ip_format):
             if address_check(icmp_request, icmp_reply, ip_format):
                 break
     else:
@@ -154,5 +163,6 @@ def main():
 
     sys.exit(0)
 
+
 if __name__ == "__main__":
     main()