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, 41 insertions, 26 deletions

diff --git a/resources/traffic_scripts/ipv6_ns.py b/resources/traffic_scripts/ipv6_ns.py
index 70c6ab445a..5852e6317f 100755
--- a/resources/traffic_scripts/ipv6_ns.py
+++ b/resources/traffic_scripts/ipv6_ns.py
@@ -17,13 +17,18 @@
 
 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.all import Ether
 from scapy.layers.inet6 import IPv6, ICMPv6ND_NA, ICMPv6ND_NS
 from scapy.layers.inet6 import ICMPv6NDOptDstLLAddr, ICMPv6NDOptSrcLLAddr
-from scapy.all import Ether
+
+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():
@@ -41,57 +46,67 @@ def main():
 
     # send ICMPv6 neighbor solicitation message
     pkt_send = (Ether(src=src_mac, dst='ff:ff:ff:ff:ff:ff') /
-                      IPv6(src=src_ip, dst='ff02::1:ff00:2') /
-                      ICMPv6ND_NS(tgt=dst_ip) /
-                      ICMPv6NDOptSrcLLAddr(lladdr=src_mac))
+                IPv6(src=src_ip, dst='ff02::1:ff00:2') /
+                ICMPv6ND_NS(tgt=dst_ip) /
+                ICMPv6NDOptSrcLLAddr(lladdr=src_mac))
     sent_packets.append(pkt_send)
     txq.send(pkt_send)
 
     # receive ICMPv6 neighbor advertisement message
-    ether = rxq.recv(2, sent_packets)
+    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 ether is None:
         raise RuntimeError('ICMPv6 echo reply Rx timeout')
 
     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(ICMPv6ND_NA):
-        raise RuntimeError(
-            'Unexpected packet with no ICMPv6 ND-NA received {0}'.format(
-                ipv6.__repr__()))
+        raise RuntimeError('Unexpected packet with no ICMPv6 ND-NA received '
+                           '{0}'.format(ipv6.__repr__()))
 
-    icmpv6_na = ipv6['ICMPv6 Neighbor Discovery - Neighbor Advertisement']
+    icmpv6_na = ipv6[ICMPv6ND_NA]
 
     # verify target address
     if icmpv6_na.tgt != dst_ip:
-        raise RuntimeError('Invalid target address {0} should be {1}'.format(
-            icmpv6_na.tgt, dst_ip))
+        raise RuntimeError('Invalid target address {0} should be {1}'.
+                           format(icmpv6_na.tgt, dst_ip))
 
     if not icmpv6_na.haslayer(ICMPv6NDOptDstLLAddr):
-        raise RuntimeError(
-            'Missing Destination Link-Layer Address option in ICMPv6 ' +
-            'Neighbor Advertisement {0}'.format(icmpv6_na.__repr__()))
+        raise RuntimeError('Missing Destination Link-Layer Address option in '
+                           'ICMPv6 Neighbor Advertisement {0}'.
+                           format(icmpv6_na.__repr__()))
 
-    option = 'ICMPv6 Neighbor Discovery Option - Destination Link-Layer Address'
-    dst_ll_addr = icmpv6_na[option]
+    dst_ll_addr = icmpv6_na[ICMPv6NDOptDstLLAddr]
 
     # verify destination link-layer address field
     if dst_ll_addr.lladdr != dst_mac:
-        raise RuntimeError('Invalid lladdr {0} should be {1}'.format(
-            dst_ll_addr.lladdr, dst_mac))
+        raise RuntimeError('Invalid lladdr {0} should be {1}'.
+                           format(dst_ll_addr.lladdr, dst_mac))
 
     # verify checksum
     cksum = icmpv6_na.cksum
     del icmpv6_na.cksum
     tmp = ICMPv6ND_NA(str(icmpv6_na))
     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()