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, 36 insertions, 22 deletions

diff --git a/resources/traffic_scripts/policer.py b/resources/traffic_scripts/policer.py
index ee9fa29c4a..62c397d496 100755
--- a/resources/traffic_scripts/policer.py
+++ b/resources/traffic_scripts/policer.py
@@ -21,7 +21,10 @@ import logging
 # pylint: disable=no-name-in-module
 # pylint: disable=import-error
 logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
-from scapy.all import Ether, IP, IPv6, TCP
+
+from scapy.all import Ether
+from scapy.layers.inet import IP, TCP
+from scapy.layers.inet6 import IPv6, ICMPv6ND_NS
 from ipaddress import ip_address
 
 from resources.libraries.python.TrafficScriptArg import TrafficScriptArg
@@ -38,17 +41,17 @@ def check_ipv4(pkt_recv, dscp):
     :raises RuntimeError: If received packet is invalid.
     """
     if not pkt_recv.haslayer(IP):
-        raise RuntimeError(
-            'Not an IPv4 packet received: {0}'.format(pkt_recv.__repr__()))
+        raise RuntimeError('Not an IPv4 packet received: {0}'.
+                           format(pkt_recv.__repr__()))
 
-    rx_dscp = pkt_recv['IP'].tos >> 2
+    rx_dscp = pkt_recv[IP].tos >> 2
     if rx_dscp != dscp:
-        raise RuntimeError(
-            'Invalid DSCP {0} should be {1}'.format(rx_dscp, dscp))
+        raise RuntimeError('Invalid DSCP {0} should be {1}'.
+                           format(rx_dscp, dscp))
 
     if not pkt_recv.haslayer(TCP):
-        raise RuntimeError(
-            'Not a TCP packet received: {0}'.format(pkt_recv.__repr__()))
+        raise RuntimeError('Not a TCP packet received: {0}'.
+                           format(pkt_recv.__repr__()))
 
 
 def check_ipv6(pkt_recv, dscp):
@@ -61,17 +64,17 @@ def check_ipv6(pkt_recv, dscp):
     :raises RuntimeError: If received packet is invalid.
     """
     if not pkt_recv.haslayer(IPv6):
-        raise RuntimeError(
-            'Not an IPv6 packet received: {0}'.format(pkt_recv.__repr__()))
+        raise RuntimeError('Not an IPv6 packet received: {0}'.
+                           format(pkt_recv.__repr__()))
 
-    rx_dscp = pkt_recv['IPv6'].tc >> 2
+    rx_dscp = pkt_recv[IPv6].tc >> 2
     if rx_dscp != dscp:
-        raise RuntimeError(
-            'Invalid DSCP {0} should be {1}'.format(rx_dscp, dscp))
+        raise RuntimeError('Invalid DSCP {0} should be {1}'.
+                           format(rx_dscp, dscp))
 
     if not pkt_recv.haslayer(TCP):
-        raise RuntimeError(
-            'Not a TCP packet received: {0}'.format(pkt_recv.__repr__()))
+        raise RuntimeError('Not a TCP packet received: {0}'.
+                           format(pkt_recv.__repr__()))
 
 
 # pylint: disable=too-many-locals
@@ -97,19 +100,29 @@ def main():
     sent_packets = []
 
     if is_ipv4:
-        ip_pkt = IP(src=src_ip, dst=dst_ip) / \
-                 TCP()
+        ip_pkt = (IP(src=src_ip, dst=dst_ip) /
+                  TCP())
     else:
-        ip_pkt = IPv6(src=src_ip, dst=dst_ip) / \
-                 TCP()
+        ip_pkt = (IPv6(src=src_ip, dst=dst_ip) /
+                  TCP())
 
-    pkt_send = Ether(src=src_mac, dst=dst_mac) / \
-               ip_pkt
+    pkt_send = (Ether(src=src_mac, dst=dst_mac) /
+                ip_pkt)
 
     sent_packets.append(pkt_send)
     txq.send(pkt_send)
 
-    pkt_recv = rxq.recv(2, sent_packets)
+    while True:
+        pkt_recv = rxq.recv(2, sent_packets)
+        if pkt_recv is None:
+            raise RuntimeError('ICMPv6 echo reply Rx timeout')
+
+        if pkt_recv.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 pkt_recv is None:
         raise RuntimeError('Rx timeout')
@@ -121,5 +134,6 @@ def main():
 
     sys.exit(0)
 
+
 if __name__ == "__main__":
     main()