VPP-1283: IPv4 PMTU missing MTU value in ICMP4 message.

Change-Id: I7a4133c59ff45b0744b48e246a049d9f015026fc
Signed-off-by: Ole Troan <ot@cisco.com>

5 files changed, 257 insertions, 34 deletions

diff --git a/src/plugins/igmp/igmp.c b/src/plugins/igmp/igmp.c
index 5ff88e58ec3..6499b5be466 100644
--- a/src/plugins/igmp/igmp.c
+++ b/src/plugins/igmp/igmp.c
@@ -712,7 +712,7 @@ igmp_timer_process (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	goto next_timer;
       IGMP_DBG ("time: %f", vlib_time_now (vm));
       /* timer expired */
-      if (NULL != timer)
+      if (NULL != timer && timer->func != NULL)
 	timer->func (vm, rt, im, timer);
     next_timer:
       timer = igmp_get_next_timer (im);
diff --git a/src/vnet/ip/icmp4.c b/src/vnet/ip/icmp4.c
index 1fe01e48500..a4808f23271 100644
--- a/src/vnet/ip/icmp4.c
+++ b/src/vnet/ip/icmp4.c
@@ -513,13 +513,15 @@ ip4_icmp_error (vlib_main_t * vm,
 		  b->current_length = 0;
 		}
 	    }
-	  p0->current_length =
-	    p0->current_length > 576 ? 576 : p0->current_length;
 
 	  /* Add IP header and ICMPv4 header including a 4 byte data field */
 	  vlib_buffer_advance (p0,
 			       -sizeof (ip4_header_t) -
 			       sizeof (icmp46_header_t) - 4);
+
+	  p0->current_length =
+	    p0->current_length > 576 ? 576 : p0->current_length;
+
 	  out_ip0 = vlib_buffer_get_current (p0);
 	  icmp0 = (icmp46_header_t *) & out_ip0[1];
 
diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index ce2d619941c..40fe9dc447e 100644
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -1963,6 +1963,29 @@ typedef enum
 #define IP4_MCAST_ADDR_MASK 0xffff7f00
 #endif
 
+always_inline void
+ip4_mtu_check (vlib_buffer_t * b, u16 packet_len,
+	       u16 adj_packet_bytes, bool df, u32 * next, u32 * error)
+{
+  if (packet_len > adj_packet_bytes)
+    {
+      *error = IP4_ERROR_MTU_EXCEEDED;
+      if (df)
+	{
+	  icmp4_error_set_vnet_buffer
+	    (b, ICMP4_destination_unreachable,
+	     ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
+	     adj_packet_bytes);
+	  *next = IP4_REWRITE_NEXT_ICMP_ERROR;
+	}
+      else
+	{
+	  /* Add support for fragmentation here */
+	  *next = IP4_REWRITE_NEXT_DROP;
+	}
+    }
+}
+
 always_inline uword
 ip4_rewrite_inline (vlib_main_t * vm,
 		    vlib_node_runtime_t * node,
@@ -2123,26 +2146,16 @@ ip4_rewrite_inline (vlib_main_t * vm,
 	  vnet_buffer (p1)->ip.save_rewrite_length = rw_len1;
 
 	  /* Check MTU of outgoing interface. */
-	  if (vlib_buffer_length_in_chain (vm, p0) >
-	      adj0[0].rewrite_header.max_l3_packet_bytes)
-	    {
-	      error0 = IP4_ERROR_MTU_EXCEEDED;
-	      next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
-	      icmp4_error_set_vnet_buffer
-		(p0, ICMP4_destination_unreachable,
-		 ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
-		 0);
-	    }
-	  if (vlib_buffer_length_in_chain (vm, p1) >
-	      adj1[0].rewrite_header.max_l3_packet_bytes)
-	    {
-	      error1 = IP4_ERROR_MTU_EXCEEDED;
-	      next1 = IP4_REWRITE_NEXT_ICMP_ERROR;
-	      icmp4_error_set_vnet_buffer
-		(p1, ICMP4_destination_unreachable,
-		 ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
-		 0);
-	    }
+	  ip4_mtu_check (p0, clib_net_to_host_u16 (ip0->length),
+			 adj0[0].rewrite_header.max_l3_packet_bytes,
+			 ip0->flags_and_fragment_offset &
+			 clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
+			 &next0, &error0);
+	  ip4_mtu_check (p1, clib_net_to_host_u16 (ip1->length),
+			 adj1[0].rewrite_header.max_l3_packet_bytes,
+			 ip1->flags_and_fragment_offset &
+			 clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
+			 &next1, &error1);
 
 	  if (is_mcast)
 	    {
@@ -2326,16 +2339,12 @@ ip4_rewrite_inline (vlib_main_t * vm,
 	       vlib_buffer_length_in_chain (vm, p0) + rw_len0);
 
 	  /* Check MTU of outgoing interface. */
-	  if (vlib_buffer_length_in_chain (vm, p0) >
-	      adj0[0].rewrite_header.max_l3_packet_bytes)
-	    {
-	      error0 = IP4_ERROR_MTU_EXCEEDED;
-	      next0 = IP4_REWRITE_NEXT_ICMP_ERROR;
-	      icmp4_error_set_vnet_buffer
-		(p0, ICMP4_destination_unreachable,
-		 ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
-		 0);
-	    }
+	  ip4_mtu_check (p0, clib_net_to_host_u16 (ip0->length),
+			 adj0[0].rewrite_header.max_l3_packet_bytes,
+			 ip0->flags_and_fragment_offset &
+			 clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT),
+			 &next0, &error0);
+
 	  if (is_mcast)
 	    {
 	      error0 = ((adj0[0].rewrite_header.sw_if_index ==
diff --git a/test/test_ip4.py b/test/test_ip4.py
index 1a611251eb5..5b5cf09c86f 100644
--- a/test/test_ip4.py
+++ b/test/test_ip4.py
@@ -1294,7 +1294,7 @@ class TestIPInput(VppTestCase):
                        dst=self.pg0.local_mac) /
                  IP(src=self.pg0.remote_ip4,
                     dst=self.pg1.remote_ip4,
-                    ttl=10) /
+                    ttl=10, flags='DF') /
                  UDP(sport=1234, dport=1234) /
                  Raw('\xa5' * 2000))
 
diff --git a/test/test_mtu.py b/test/test_mtu.py
new file mode 100644
index 00000000000..abf0c94b268
--- /dev/null
+++ b/test/test_mtu.py
@@ -0,0 +1,212 @@
+#!/usr/bin/env python
+"""IP4 and IP6 MTU functional tests"""
+
+#
+# Add tests for:
+# - sub interfaces
+# - Verify that adjacencies inherit MTU correctly
+# - Verify that sub-interfaces inherit MTU correctly
+# - Different types of interfaces?
+#
+import unittest
+from scapy.layers.inet6 import IPv6, Ether, IP, UDP, ICMPv6PacketTooBig
+from scapy.layers.inet import ICMP
+from framework import VppTestCase, VppTestRunner
+from vpp_ip_route import VppIpRoute, VppRoutePath, DpoProto
+from socket import AF_INET, AF_INET6, inet_pton
+import StringIO
+
+""" Test_mtu is a subclass of VPPTestCase classes.
+    MTU tests.
+"""
+
+
+def reassemble(listoffragments):
+    buffer = StringIO.StringIO()
+    first = listoffragments[0]
+    buffer.seek(20)
+    for pkt in listoffragments:
+        # pkt.show2()
+        buffer.seek(pkt[IP].frag*8)
+        buffer.write(pkt[IP].payload)
+    first.len = len(buffer.getvalue()) + 20
+    first.flags = 0
+    del(first.chksum)
+    header = str(first[IP])[:20]
+    return first[IP].__class__(header + buffer.getvalue())
+
+
+class TestMTU(VppTestCase):
+    """ MTU Test Case """
+
+    @classmethod
+    def setUpClass(cls):
+        super(TestMTU, cls).setUpClass()
+        cls.create_pg_interfaces(range(2))
+        cls.interfaces = list(cls.pg_interfaces)
+
+    def setUp(cls):
+        super(TestMTU, cls).setUp()
+        for i in cls.interfaces:
+            i.admin_up()
+            i.config_ip4()
+            i.config_ip6()
+            i.disable_ipv6_ra()
+            i.resolve_arp()
+            i.resolve_ndp()
+
+    def tearDown(self):
+        super(TestMTU, self).tearDown()
+        if not self.vpp_dead:
+            for i in self.pg_interfaces:
+                i.unconfig_ip4()
+                i.unconfig_ip6()
+                i.admin_down()
+
+    def validate(self, rx, expected):
+        self.assertEqual(rx, expected.__class__(str(expected)))
+
+    def validate_bytes(self, rx, expected):
+        self.assertEqual(rx, expected)
+
+    def payload(self, len):
+        return 'x' * len
+
+    def get_mtu(self, sw_if_index):
+        rv = self.vapi.sw_interface_dump()
+        for i in rv:
+            if i.sw_if_index == sw_if_index:
+                return i.link_mtu
+        return 0
+
+    def test_ip4_mtu(self):
+        """ IP4 MTU test """
+
+        #
+        # TODO: Link MTU is 216 bytes 'off'. Fix when L3 MTU patches committed
+        #
+        mtu_offset = 216
+        p_ether = Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
+        p_ip4 = IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4,
+                   flags='DF')
+
+        # TODO: Re-enable when MTU fixes are committed
+        current_mtu = self.get_mtu(self.pg1.sw_if_index)
+        current_mtu -= mtu_offset
+
+        p_payload = UDP(sport=1234, dport=1234) / self.payload(
+            current_mtu - 20 - 8)
+
+        p4 = p_ether / p_ip4 / p_payload
+        p4_reply = p_ip4 / p_payload
+        p4_reply.ttl -= 1
+        rx = self.send_and_expect(self.pg0, p4*11, self.pg1)
+        for p in rx:
+            self.validate(p[1], p4_reply)
+
+        # MTU
+        self.vapi.sw_interface_set_mtu(self.pg1.sw_if_index, 576 + mtu_offset)
+        self.assertEqual(576, self.get_mtu(self.pg1.sw_if_index) - mtu_offset)
+
+        # Should fail. Too large MTU
+        p_icmp4 = ICMP(type='dest-unreach', code='fragmentation-needed',
+                       nexthopmtu=576, chksum=0x2dbb)
+        icmp4_reply = (IP(src=self.pg0.local_ip4,
+                          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__(str(icmp4_reply))
+        s = str(icmp4_reply)
+        icmp4_reply = s[0:576]
+        rx = self.send_and_expect(self.pg0, p4*11, self.pg0)
+        for p in rx:
+            # p.show2()
+            # n.show2()
+            self.validate_bytes(str(p[1]), icmp4_reply)
+
+        '''
+        # Now with DF off. Expect fragments.
+        # First go with 1500 byte packets.
+        p_payload = UDP(sport=1234, dport=1234) / self.payload(
+            1500 - 20 - 8)
+        p4 = p_ether / p_ip4 / p_payload
+        p4.flags = 0
+        p4_reply = p_ip4 / p_payload
+        p4_reply.ttl = 62 # check this
+        p4_reply.flags = 0
+        p4_reply.id = 256
+        self.pg_enable_capture()
+        self.pg0.add_stream(p4*1)
+        self.pg_start()
+        rx = self.pg1.get_capture(3)
+        print('RX', len(rx))
+        reass_pkt = reassemble(rx)
+        self.validate(reass_pkt, p4_reply)
+        '''
+        # Now what happens with a 9K frame
+        '''
+        p_payload = UDP(sport=1234, dport=1234) / self.payload(
+            current_mtu - 20 - 8)
+        p4 = p_ether / p_ip4 / p_payload
+        p4.flags = 0
+        p4_reply = p_ip4 / p_payload
+        p4_reply.ttl = 62 # check this
+        p4_reply.flags = 0
+        p4_reply.id = 512
+
+        self.pg_enable_capture()
+        self.pg0.add_stream(p4*1)
+        self.pg_start()
+        rx = self.pg1.get_capture(16)
+        reass_pkt = reassemble(rx)
+        reass_pkt.show2()
+        p4_reply.show2()
+        self.validate(reass_pkt, p4_reply)
+        '''
+        # Reset MTU
+        self.vapi.sw_interface_set_mtu(self.pg1.sw_if_index, current_mtu)
+
+    @unittest.skip("Enable when IPv6 fragmentation is added")
+    def test_ip6_mtu(self):
+        """ IP6 MTU test """
+
+        p_ether = Ether(src=self.pg0.remote_mac, dst=self.pg0.local_mac)
+        p_ip6 = IPv6(src=self.pg0.remote_ip6, dst=self.pg1.remote_ip6)
+
+        current_mtu = self.get_mtu(self.pg1.sw_if_index)
+        p_payload = UDP(sport=1234, dport=1234) / self.payload(
+            current_mtu - 40 - 8)
+
+        p6 = p_ether / p_ip6 / p_payload
+        p6_reply = p_ip6 / p_payload
+        p6_reply.hlim -= 1
+        rx = self.send_and_expect(self.pg0, p6*9, self.pg1)
+        for p in rx:
+            self.validate(p[1], p6_reply)
+
+        # MTU (only checked on encap)
+        self.vapi.sw_interface_set_mtu(self.pg1.sw_if_index, 1280)
+        self.assertEqual(1280, self.get_mtu(self.pg1.sw_if_index))
+
+        # Should fail. Too large MTU
+        p_icmp6 = ICMPv6PacketTooBig(mtu=1280, cksum=0x4c7a)
+        icmp6_reply = (IPv6(src=self.pg0.local_ip6,
+                            dst=self.pg0.remote_ip6,
+                            hlim=254, plen=1240) /
+                       p_icmp6 / p_ip6 / p_payload)
+        icmp6_reply[2].hlim -= 1
+        n = icmp6_reply.__class__(str(icmp6_reply))
+        s = str(icmp6_reply)
+        icmp6_reply = s[0:1280]
+
+        rx = self.send_and_expect(self.pg0, p6*9, self.pg0)
+        for p in rx:
+            self.validate_bytes(str(p[1]), icmp6_reply)
+
+        # Reset MTU
+        self.vapi.sw_interface_set_mtu(self.pg1.sw_if_index, current_mtu)
+
+
+if __name__ == '__main__':
+    unittest.main(testRunner=VppTestRunner)