ip: Fragmentation fixes

Type: fix

if the packet is about to be fragmented, then don't call any of the
actions that expect the rewrite to have been written.
1) don't double count packets thru the adjacency (original & fragments)
2) don't double decrement the TTL for fragments
3) return to ip4-midchain post ip-frag if that's where we started.
4) only run midchain/mcast fixups if not fragmenting (if no errors)

Change-Id: Ib2866787a42713ee5871b87b597d8f74b901044b
Signed-off-by: Neale Ranns <nranns@cisco.com>

4 files changed, 34 insertions, 6 deletions

diff --git a/test/test_ip4.py b/test/test_ip4.py
index 831685150a2..a043be8b922 100644
--- a/test/test_ip4.py
+++ b/test/test_ip4.py
@@ -21,6 +21,7 @@ from vpp_ip_route import VppIpRoute, VppRoutePath, VppIpMRoute, \
 from vpp_ip import VppIpAddress
 from vpp_sub_interface import VppSubInterface, VppDot1QSubint, VppDot1ADSubint
 from vpp_papi import VppEnum
+from vpp_neighbor import VppNeighbor
 
 NUM_PKTS = 67
 
@@ -1918,12 +1919,19 @@ class TestIPv4Frag(VppTestCase):
     def test_frag_large_packets(self):
         """ Fragmentation of large packets """
 
+        self.vapi.cli("adjacency counters enable")
+
         p = (Ether(dst=self.src_if.local_mac, src=self.src_if.remote_mac) /
              IP(src=self.src_if.remote_ip4, dst=self.dst_if.remote_ip4) /
              UDP(sport=1234, dport=5678) / Raw())
         self.extend_packet(p, 6000, "abcde")
         saved_payload = p[Raw].load
 
+        nbr = VppNeighbor(self,
+                          self.dst_if.sw_if_index,
+                          self.dst_if.remote_mac,
+                          self.dst_if.remote_ip4).add_vpp_config()
+
         # Force fragmentation by setting MTU of output interface
         # lower than packet size
         self.vapi.sw_interface_set_mtu(self.dst_if.sw_if_index,
@@ -1937,6 +1945,9 @@ class TestIPv4Frag(VppTestCase):
         # cannot be larger then VPP buffer size (which is 2048)
         packets = self.dst_if.get_capture(3)
 
+        # we should show 3 packets thru the neighbor
+        self.assertEqual(3, nbr.get_stats()['packets'])
+
         # Assume VPP sends the fragments in order
         payload = b''
         for p in packets:
diff --git a/test/test_ipip.py b/test/test_ipip.py
index 1887417a5e0..a259a5d18fa 100644
--- a/test/test_ipip.py
+++ b/test/test_ipip.py
@@ -2,7 +2,7 @@
 """IP{4,6} over IP{v,6} tunnel functional tests"""
 
 import unittest
-from scapy.layers.inet6 import IPv6, Ether, IP, UDP, IPv6ExtHdrFragment
+from scapy.layers.inet6 import IPv6, Ether, IP, UDP, IPv6ExtHdrFragment, Raw
 from scapy.all import fragment, fragment6, RandShort, defragment6
 from framework import VppTestCase, VppTestRunner
 from vpp_ip import DpoProto
@@ -81,7 +81,7 @@ class TestIPIP(VppTestCase):
         p_ether = Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
         p_ip6 = IPv6(src="1::1", dst="DEAD::1", nh='UDP', tc=42)
         p_ip4 = IP(src="1.2.3.4", dst="130.67.0.1", tos=42)
-        p_payload = UDP(sport=1234, dport=1234)
+        p_payload = UDP(sport=1234, dport=1234) / Raw(b'X' * 100)
 
         # IPv4 transport
         rv = ipip_add_tunnel(self,
@@ -121,6 +121,7 @@ class TestIPIP(VppTestCase):
         rx = self.send_and_expect(self.pg0, p6 * 10, self.pg1)
         for p in rx:
             self.validate(p[1], p6_reply)
+            self.assert_packet_checksums_valid(p)
 
         # IPv4 in to IPv4 tunnel
         p4 = (p_ether / p_ip4 / p_payload)
@@ -134,6 +135,7 @@ class TestIPIP(VppTestCase):
         rx = self.send_and_expect(self.pg0, p4 * 10, self.pg1)
         for p in rx:
             self.validate(p[1], p4_reply)
+            self.assert_packet_checksums_valid(p)
 
         # Decapsulation
         p_ether = Ether(src=self.pg1.remote_mac, dst=self.pg1.local_mac)
@@ -147,6 +149,7 @@ class TestIPIP(VppTestCase):
         rx = self.send_and_expect(self.pg1, p4 * 10, self.pg0)
         for p in rx:
             self.validate(p[1], p4_reply)
+            self.assert_packet_checksums_valid(p)
 
         err = self.statistics.get_err_counter(
             '/err/ipip4-input/packets decapsulated')
@@ -161,6 +164,7 @@ class TestIPIP(VppTestCase):
         rx = self.send_and_expect(self.pg1, p6 * 10, self.pg0)
         for p in rx:
             self.validate(p[1], p6_reply)
+            self.assert_packet_checksums_valid(p)
 
         err = self.statistics.get_err_counter(
             '/err/ipip4-input/packets decapsulated')
@@ -222,7 +226,6 @@ class TestIPIP(VppTestCase):
         self.pg_start()
         rx = self.pg0.get_capture(6)
         reass_pkt = reassemble4(rx)
-        p4_reply.ttl -= 1
         p4_reply.id = 256
         self.validate(reass_pkt, p4_reply)
 
@@ -233,10 +236,24 @@ class TestIPIP(VppTestCase):
         self.pg_start()
         rx = self.pg0.get_capture(2)
         reass_pkt = reassemble4(rx)
-        p4_reply.ttl -= 1
         p4_reply.id = 512
         self.validate(reass_pkt, p4_reply)
 
+        # send large packets through the tunnel, expect them to be fragmented
+        self.vapi.sw_interface_set_mtu(sw_if_index, [600, 0, 0, 0])
+
+        p4 = (Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac) /
+              IP(src="1.2.3.4", dst="130.67.0.1", tos=42) /
+              UDP(sport=1234, dport=1234) / Raw(b'Q' * 1000))
+        rx = self.send_and_expect(self.pg0, p4 * 15, self.pg1, 30)
+        inners = []
+        for p in rx:
+            inners.append(p[IP].payload)
+        reass_pkt = reassemble4(inners)
+        for p in reass_pkt:
+            self.assert_packet_checksums_valid(p)
+            self.assertEqual(p[IP].ttl, 63)
+
     def test_ipip_create(self):
         """ ipip create / delete interface test """
         rv = ipip_add_tunnel(self, '1.2.3.4', '2.3.4.5')
diff --git a/test/test_mtu.py b/test/test_mtu.py
index 568a147a9a4..c18ef9f4cdf 100644
--- a/test/test_mtu.py
+++ b/test/test_mtu.py
@@ -101,7 +101,6 @@ class TestMTU(VppTestCase):
                           dst=self.pg0.remote_ip4,
                           ttl=254, len=576, id=0) /
                        p_icmp4 / p_ip4 / p_payload)
-        icmp4_reply[1].ttl -= 1
         n = icmp4_reply.__class__(icmp4_reply)
         s = bytes(icmp4_reply)
         icmp4_reply = s[0:576]
@@ -118,7 +117,7 @@ class TestMTU(VppTestCase):
         p4 = p_ether / p_ip4 / p_payload
         p4.flags = 0
         p4_reply = p_ip4 / p_payload
-        p4_reply.ttl = 62  # check this
+        p4_reply.ttl = p_ip4.ttl - 1
         p4_reply.flags = 0
         p4_reply.id = 256
         self.pg_enable_capture()
diff --git a/test/vpp_neighbor.py b/test/vpp_neighbor.py
index eb9635fd603..f906c2a5af3 100644
--- a/test/vpp_neighbor.py
+++ b/test/vpp_neighbor.py
@@ -58,6 +58,7 @@ class VppNeighbor(VppObject):
             flags=self.flags)
         self.stats_index = r.stats_index
         self._test.registry.register(self, self._test.logger)
+        return self
 
     def remove_vpp_config(self):
         self._test.vapi.ip_neighbor_add_del(