make test: improve handling of packet captures

Perform accounting of expected packets based on created packet infos.
Use this accounting info to automatically expect (and verify) the
correct number of packets to be captured. Automatically retry the read
of the capture file if scapy raises an exception while doing so to
handle rare cases when capture file is read while only partially
written during busy wait. Don't fail assert_nothing_captured if only
junk packets arrived.

Change-Id: I16ec2e9410ef510d313ec16b7e13c57d0b2a63f5
Signed-off-by: Klement Sekera <ksekera@cisco.com>

1 files changed, 24 insertions, 17 deletions

diff --git a/test/test_mpls.py b/test/test_mpls.py
index 6d5eeb2b..806e69dc 100644
--- a/test/test_mpls.py
+++ b/test/test_mpls.py
@@ -12,6 +12,7 @@ from scapy.layers.inet import IP, UDP, ICMP
 from scapy.layers.inet6 import IPv6
 from scapy.contrib.mpls import MPLS
 
+
 class TestMPLS(VppTestCase):
     """ MPLS Test Case """
 
@@ -44,11 +45,17 @@ class TestMPLS(VppTestCase):
         super(TestMPLS, self).tearDown()
 
     # the default of 64 matches the IP packet TTL default
-    def create_stream_labelled_ip4(self, src_if, mpls_labels, mpls_ttl=255, ping=0, ip_itf=None):
+    def create_stream_labelled_ip4(
+            self,
+            src_if,
+            mpls_labels,
+            mpls_ttl=255,
+            ping=0,
+            ip_itf=None):
+        self.reset_packet_infos()
         pkts = []
         for i in range(0, 257):
-            info = self.create_packet_info(src_if.sw_if_index,
-                                           src_if.sw_if_index)
+            info = self.create_packet_info(src_if, src_if)
             payload = self.info_to_payload(info)
             p = Ether(dst=src_if.local_mac, src=src_if.remote_mac)
 
@@ -71,10 +78,10 @@ class TestMPLS(VppTestCase):
         return pkts
 
     def create_stream_ip4(self, src_if, dst_ip):
+        self.reset_packet_infos()
         pkts = []
         for i in range(0, 257):
-            info = self.create_packet_info(src_if.sw_if_index,
-                                           src_if.sw_if_index)
+            info = self.create_packet_info(src_if, src_if)
             payload = self.info_to_payload(info)
             p = (Ether(dst=src_if.local_mac, src=src_if.remote_mac) /
                  IP(src=src_if.remote_ip4, dst=dst_ip) /
@@ -85,10 +92,10 @@ class TestMPLS(VppTestCase):
         return pkts
 
     def create_stream_labelled_ip6(self, src_if, mpls_label, mpls_ttl):
+        self.reset_packet_infos()
         pkts = []
         for i in range(0, 257):
-            info = self.create_packet_info(src_if.sw_if_index,
-                                           src_if.sw_if_index)
+            info = self.create_packet_info(src_if, src_if)
             payload = self.info_to_payload(info)
             p = (Ether(dst=src_if.local_mac, src=src_if.remote_mac) /
                  MPLS(label=mpls_label, ttl=mpls_ttl) /
@@ -342,7 +349,6 @@ class TestMPLS(VppTestCase):
                                             labels=[44, 45])])
         route_34_eos.add_vpp_config()
 
-        self.vapi.cli("clear trace")
         tx = self.create_stream_labelled_ip4(self.pg0, [34])
         self.pg0.add_stream(tx)
 
@@ -628,7 +634,6 @@ class TestMPLS(VppTestCase):
         # a stream with a non-zero MPLS TTL
         # PG0 is in the default table
         #
-        self.vapi.cli("clear trace")
         tx = self.create_stream_labelled_ip4(self.pg0, [0])
         self.pg0.add_stream(tx)
 
@@ -692,9 +697,9 @@ class TestMPLS(VppTestCase):
         # A de-agg route - next-hop lookup in default table
         #
         route_34_eos = MplsRoute(self, 34, 1,
-                                  [RoutePath("0.0.0.0",
-                                             0xffffffff,
-                                             nh_table_id=0)])
+                                 [RoutePath("0.0.0.0",
+                                            0xffffffff,
+                                            nh_table_id=0)])
         route_34_eos.add_vpp_config()
 
         #
@@ -716,9 +721,9 @@ class TestMPLS(VppTestCase):
         # A de-agg route - next-hop lookup in non-default table
         #
         route_35_eos = MplsRoute(self, 35, 1,
-                                  [RoutePath("0.0.0.0",
-                                             0xffffffff,
-                                             nh_table_id=1)])
+                                 [RoutePath("0.0.0.0",
+                                            0xffffffff,
+                                            nh_table_id=1)])
         route_35_eos.add_vpp_config()
 
         #
@@ -727,13 +732,15 @@ class TestMPLS(VppTestCase):
         # default table and egress unlabelled in the non-default
         #
         self.vapi.cli("clear trace")
-        tx = self.create_stream_labelled_ip4(self.pg0, [35], ping=1, ip_itf=self.pg1)
+        tx = self.create_stream_labelled_ip4(
+            self.pg0, [35], ping=1, ip_itf=self.pg1)
         self.pg0.add_stream(tx)
 
         self.pg_enable_capture(self.pg_interfaces)
         self.pg_start()
 
-        rx = self.pg1.get_capture()
+        packet_count = self.get_packet_count_for_if_idx(self.pg0.sw_if_index)
+        rx = self.pg1.get_capture(packet_count)
         self.verify_capture_ip4(self.pg1, rx, tx, ping_resp=1)
 
         route_35_eos.remove_vpp_config()