Refactor IP input checks for re-use at MPLS disposition

Change-Id: I7aafdecd6f370411138e6ab67b2ff72cda6e0666
Signed-off-by: Neale Ranns <nranns@cisco.com>

4 files changed, 411 insertions, 257 deletions

diff --git a/src/vnet/ip/ip4_input.c b/src/vnet/ip/ip4_input.c
index 3b08f4b0089..121f40f473d 100644
--- a/src/vnet/ip/ip4_input.c
+++ b/src/vnet/ip/ip4_input.c
@@ -37,7 +37,7 @@
  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
-#include <vnet/ip/ip.h>
+#include <vnet/ip/ip4_input.h>
 #include <vnet/ethernet/ethernet.h>
 #include <vnet/ppp/ppp.h>
 #include <vnet/hdlc/hdlc.h>
@@ -60,16 +60,6 @@ format_ip4_input_trace (u8 * s, va_list * va)
   return s;
 }
 
-typedef enum
-{
-  IP4_INPUT_NEXT_DROP,
-  IP4_INPUT_NEXT_PUNT,
-  IP4_INPUT_NEXT_LOOKUP,
-  IP4_INPUT_NEXT_LOOKUP_MULTICAST,
-  IP4_INPUT_NEXT_ICMP_ERROR,
-  IP4_INPUT_N_NEXT,
-} ip4_input_next_t;
-
 /* Validate IP v4 packets and pass them either to forwarding code
    or drop/punt exception packets. */
 always_inline uword
@@ -109,10 +99,9 @@ ip4_input_inline (vlib_main_t * vm,
 	{
 	  vlib_buffer_t *p0, *p1;
 	  ip4_header_t *ip0, *ip1;
-	  u32 sw_if_index0, pi0, ip_len0, cur_len0, next0;
-	  u32 sw_if_index1, pi1, ip_len1, cur_len1, next1;
-	  i32 len_diff0, len_diff1;
-	  u8 error0, error1, arc0, arc1;
+	  u32 sw_if_index0, pi0, next0;
+	  u32 sw_if_index1, pi1, next1;
+	  u8 arc0, arc1;
 
 	  /* Prefetch next iteration. */
 	  {
@@ -144,8 +133,6 @@ ip4_input_inline (vlib_main_t * vm,
 	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
 	  sw_if_index1 = vnet_buffer (p1)->sw_if_index[VLIB_RX];
 
-	  error0 = error1 = IP4_ERROR_NONE;
-
 	  if (PREDICT_FALSE (ip4_address_is_multicast (&ip0->dst_address)))
 	    {
 	      arc0 = lm->mcast_feature_arc_index;
@@ -155,8 +142,6 @@ ip4_input_inline (vlib_main_t * vm,
 	    {
 	      arc0 = lm->ucast_feature_arc_index;
 	      next0 = IP4_INPUT_NEXT_LOOKUP;
-	      if (PREDICT_FALSE (ip0->ttl < 1))
-		error0 = IP4_ERROR_TIME_EXPIRED;
 	    }
 
 	  if (PREDICT_FALSE (ip4_address_is_multicast (&ip1->dst_address)))
@@ -168,8 +153,6 @@ ip4_input_inline (vlib_main_t * vm,
 	    {
 	      arc1 = lm->ucast_feature_arc_index;
 	      next1 = IP4_INPUT_NEXT_LOOKUP;
-	      if (PREDICT_FALSE (ip1->ttl < 1))
-		error1 = IP4_ERROR_TIME_EXPIRED;
 	    }
 
 	  vnet_buffer (p0)->ip.adj_index[VLIB_RX] = ~0;
@@ -180,82 +163,9 @@ ip4_input_inline (vlib_main_t * vm,
 
 	  vlib_increment_simple_counter (cm, thread_index, sw_if_index0, 1);
 	  vlib_increment_simple_counter (cm, thread_index, sw_if_index1, 1);
-
-	  /* Punt packets with options or wrong version. */
-	  if (PREDICT_FALSE (ip0->ip_version_and_header_length != 0x45))
-	    error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ?
-	      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
-
-	  if (PREDICT_FALSE (ip1->ip_version_and_header_length != 0x45))
-	    error1 = (ip1->ip_version_and_header_length & 0xf) != 5 ?
-	      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
-
-	  /* Verify header checksum. */
-	  if (verify_checksum)
-	    {
-	      ip_csum_t sum0, sum1;
-
-	      ip4_partial_header_checksum_x1 (ip0, sum0);
-	      ip4_partial_header_checksum_x1 (ip1, sum1);
-
-	      error0 = 0xffff != ip_csum_fold (sum0) ?
-		IP4_ERROR_BAD_CHECKSUM : error0;
-	      error1 = 0xffff != ip_csum_fold (sum1) ?
-		IP4_ERROR_BAD_CHECKSUM : error1;
-	    }
-
-	  /* Drop fragmentation offset 1 packets. */
-	  error0 = ip4_get_fragment_offset (ip0) == 1 ?
-	    IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;
-	  error1 = ip4_get_fragment_offset (ip1) == 1 ?
-	    IP4_ERROR_FRAGMENT_OFFSET_ONE : error1;
-
-	  /* Verify lengths. */
-	  ip_len0 = clib_net_to_host_u16 (ip0->length);
-	  ip_len1 = clib_net_to_host_u16 (ip1->length);
-
-	  /* IP length must be at least minimal IP header. */
-	  error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;
-	  error1 = ip_len1 < sizeof (ip1[0]) ? IP4_ERROR_TOO_SHORT : error1;
-
-	  cur_len0 = vlib_buffer_length_in_chain (vm, p0);
-	  cur_len1 = vlib_buffer_length_in_chain (vm, p1);
-
-	  len_diff0 = cur_len0 - ip_len0;
-	  len_diff1 = cur_len1 - ip_len1;
-
-	  error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;
-	  error1 = len_diff1 < 0 ? IP4_ERROR_BAD_LENGTH : error1;
-
-	  p0->error = error_node->errors[error0];
-	  p1->error = error_node->errors[error1];
-
-	  if (PREDICT_FALSE (error0 != IP4_ERROR_NONE))
-	    {
-	      if (error0 == IP4_ERROR_TIME_EXPIRED)
-		{
-		  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
-					       ICMP4_time_exceeded_ttl_exceeded_in_transit,
-					       0);
-		  next0 = IP4_INPUT_NEXT_ICMP_ERROR;
-		}
-	      else
-		next0 = error0 != IP4_ERROR_OPTIONS ?
-		  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
-	    }
-	  if (PREDICT_FALSE (error1 != IP4_ERROR_NONE))
-	    {
-	      if (error1 == IP4_ERROR_TIME_EXPIRED)
-		{
-		  icmp4_error_set_vnet_buffer (p1, ICMP4_time_exceeded,
-					       ICMP4_time_exceeded_ttl_exceeded_in_transit,
-					       0);
-		  next1 = IP4_INPUT_NEXT_ICMP_ERROR;
-		}
-	      else
-		next1 = error1 != IP4_ERROR_OPTIONS ?
-		  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
-	    }
+	  ip4_input_check_x2 (vm, error_node,
+			      p0, p1, ip0, ip1,
+			      &next0, &next1, verify_checksum);
 
 	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
 					   to_next, n_left_to_next,
@@ -265,9 +175,8 @@ ip4_input_inline (vlib_main_t * vm,
 	{
 	  vlib_buffer_t *p0;
 	  ip4_header_t *ip0;
-	  u32 sw_if_index0, pi0, ip_len0, cur_len0, next0;
-	  i32 len_diff0;
-	  u8 error0, arc0;
+	  u32 sw_if_index0, pi0, next0;
+	  u8 arc0;
 
 	  pi0 = from[0];
 	  to_next[0] = pi0;
@@ -281,8 +190,6 @@ ip4_input_inline (vlib_main_t * vm,
 
 	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
 
-	  error0 = IP4_ERROR_NONE;
-
 	  if (PREDICT_FALSE (ip4_address_is_multicast (&ip0->dst_address)))
 	    {
 	      arc0 = lm->mcast_feature_arc_index;
@@ -292,60 +199,14 @@ ip4_input_inline (vlib_main_t * vm,
 	    {
 	      arc0 = lm->ucast_feature_arc_index;
 	      next0 = IP4_INPUT_NEXT_LOOKUP;
-	      if (PREDICT_FALSE (ip0->ttl < 1))
-		error0 = IP4_ERROR_TIME_EXPIRED;
 	    }
 
 	  vnet_buffer (p0)->ip.adj_index[VLIB_RX] = ~0;
 	  vnet_feature_arc_start (arc0, sw_if_index0, &next0, p0);
 
 	  vlib_increment_simple_counter (cm, thread_index, sw_if_index0, 1);
-
-	  /* Punt packets with options or wrong version. */
-	  if (PREDICT_FALSE (ip0->ip_version_and_header_length != 0x45))
-	    error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ?
-	      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
-
-	  /* Verify header checksum. */
-	  if (verify_checksum)
-	    {
-	      ip_csum_t sum0;
-
-	      ip4_partial_header_checksum_x1 (ip0, sum0);
-	      error0 =
-		0xffff !=
-		ip_csum_fold (sum0) ? IP4_ERROR_BAD_CHECKSUM : error0;
-	    }
-
-	  /* Drop fragmentation offset 1 packets. */
-	  error0 =
-	    ip4_get_fragment_offset (ip0) ==
-	    1 ? IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;
-
-	  /* Verify lengths. */
-	  ip_len0 = clib_net_to_host_u16 (ip0->length);
-
-	  /* IP length must be at least minimal IP header. */
-	  error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;
-
-	  cur_len0 = vlib_buffer_length_in_chain (vm, p0);
-	  len_diff0 = cur_len0 - ip_len0;
-	  error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;
-
-	  p0->error = error_node->errors[error0];
-	  if (PREDICT_FALSE (error0 != IP4_ERROR_NONE))
-	    {
-	      if (error0 == IP4_ERROR_TIME_EXPIRED)
-		{
-		  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
-					       ICMP4_time_exceeded_ttl_exceeded_in_transit,
-					       0);
-		  next0 = IP4_INPUT_NEXT_ICMP_ERROR;
-		}
-	      else
-		next0 = error0 != IP4_ERROR_OPTIONS ?
-		  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
-	    }
+	  ip4_input_check_x1 (vm, error_node, p0, ip0, &next0,
+			      verify_checksum);
 
 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
@@ -406,7 +267,7 @@ ip4_input_no_checksum (vlib_main_t * vm,
   return ip4_input_inline (vm, node, frame, /* verify_checksum */ 0);
 }
 
-static char *ip4_error_strings[] = {
+char *ip4_error_strings[] = {
 #define _(sym,string) string,
   foreach_ip4_error
 #undef _
diff --git a/src/vnet/ip/ip4_input.h b/src/vnet/ip/ip4_input.h
new file mode 100644
index 00000000000..75306a34db3
--- /dev/null
+++ b/src/vnet/ip/ip4_input.h
@@ -0,0 +1,223 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * ip/ip4_input.c: IP v4 input node
+ *
+ * Copyright (c) 2008 Eliot Dresselhaus
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef included_ip_input_h
+#define included_ip_input_h
+
+#include <vnet/ip/ip.h>
+#include <vnet/ethernet/ethernet.h>
+
+extern char *ip4_error_strings[];
+
+typedef enum
+{
+  IP4_INPUT_NEXT_DROP,
+  IP4_INPUT_NEXT_PUNT,
+  IP4_INPUT_NEXT_LOOKUP,
+  IP4_INPUT_NEXT_LOOKUP_MULTICAST,
+  IP4_INPUT_NEXT_ICMP_ERROR,
+  IP4_INPUT_N_NEXT,
+} ip4_input_next_t;
+
+always_inline void
+ip4_input_check_x2 (vlib_main_t * vm,
+		    vlib_node_runtime_t * error_node,
+		    vlib_buffer_t * p0, vlib_buffer_t * p1,
+		    ip4_header_t * ip0, ip4_header_t * ip1,
+		    u32 * next0, u32 * next1, int verify_checksum)
+{
+  u8 error0, error1;
+  u32 ip_len0, cur_len0;
+  u32 ip_len1, cur_len1;
+  i32 len_diff0, len_diff1;
+
+  error0 = error1 = IP4_ERROR_NONE;
+
+  /* Punt packets with options or wrong version. */
+  if (PREDICT_FALSE (ip0->ip_version_and_header_length != 0x45))
+    error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ?
+      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
+
+  if (PREDICT_FALSE (ip1->ip_version_and_header_length != 0x45))
+    error1 = (ip1->ip_version_and_header_length & 0xf) != 5 ?
+      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
+
+  if (PREDICT_FALSE (ip0->ttl < 1))
+    error0 = IP4_ERROR_TIME_EXPIRED;
+  if (PREDICT_FALSE (ip1->ttl < 1))
+    error1 = IP4_ERROR_TIME_EXPIRED;
+
+  /* Verify header checksum. */
+  if (verify_checksum)
+    {
+      ip_csum_t sum0, sum1;
+
+      ip4_partial_header_checksum_x1 (ip0, sum0);
+      ip4_partial_header_checksum_x1 (ip1, sum1);
+
+      error0 = 0xffff != ip_csum_fold (sum0) ?
+	IP4_ERROR_BAD_CHECKSUM : error0;
+      error1 = 0xffff != ip_csum_fold (sum1) ?
+	IP4_ERROR_BAD_CHECKSUM : error1;
+    }
+
+  /* Drop fragmentation offset 1 packets. */
+  error0 = ip4_get_fragment_offset (ip0) == 1 ?
+    IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;
+  error1 = ip4_get_fragment_offset (ip1) == 1 ?
+    IP4_ERROR_FRAGMENT_OFFSET_ONE : error1;
+
+  /* Verify lengths. */
+  ip_len0 = clib_net_to_host_u16 (ip0->length);
+  ip_len1 = clib_net_to_host_u16 (ip1->length);
+
+  /* IP length must be at least minimal IP header. */
+  error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;
+  error1 = ip_len1 < sizeof (ip1[0]) ? IP4_ERROR_TOO_SHORT : error1;
+
+  cur_len0 = vlib_buffer_length_in_chain (vm, p0);
+  cur_len1 = vlib_buffer_length_in_chain (vm, p1);
+
+  len_diff0 = cur_len0 - ip_len0;
+  len_diff1 = cur_len1 - ip_len1;
+
+  error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;
+  error1 = len_diff1 < 0 ? IP4_ERROR_BAD_LENGTH : error1;
+
+  if (PREDICT_FALSE (error0 != IP4_ERROR_NONE))
+    {
+      if (error0 == IP4_ERROR_TIME_EXPIRED)
+	{
+	  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next0 = IP4_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	*next0 = error0 != IP4_ERROR_OPTIONS ?
+	  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
+    }
+  if (PREDICT_FALSE (error1 != IP4_ERROR_NONE))
+    {
+      if (error1 == IP4_ERROR_TIME_EXPIRED)
+	{
+	  icmp4_error_set_vnet_buffer (p1, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next1 = IP4_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	*next1 = error1 != IP4_ERROR_OPTIONS ?
+	  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
+    }
+
+  p0->error = error_node->errors[error0];
+  p1->error = error_node->errors[error1];
+}
+
+always_inline void
+ip4_input_check_x1 (vlib_main_t * vm,
+		    vlib_node_runtime_t * error_node,
+		    vlib_buffer_t * p0,
+		    ip4_header_t * ip0, u32 * next0, int verify_checksum)
+{
+  u32 ip_len0, cur_len0;
+  i32 len_diff0;
+  u8 error0;
+
+  error0 = IP4_ERROR_NONE;
+
+  /* Punt packets with options or wrong version. */
+  if (PREDICT_FALSE (ip0->ip_version_and_header_length != 0x45))
+    error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ?
+      IP4_ERROR_OPTIONS : IP4_ERROR_VERSION;
+
+  /* Verify header checksum. */
+  if (verify_checksum)
+    {
+      ip_csum_t sum0;
+
+      ip4_partial_header_checksum_x1 (ip0, sum0);
+
+      error0 = 0xffff != ip_csum_fold (sum0) ?
+	IP4_ERROR_BAD_CHECKSUM : error0;
+    }
+
+  /* Drop fragmentation offset 1 packets. */
+  error0 = ip4_get_fragment_offset (ip0) == 1 ?
+    IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;
+
+  /* Verify lengths. */
+  ip_len0 = clib_net_to_host_u16 (ip0->length);
+
+  /* IP length must be at least minimal IP header. */
+  error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;
+
+  cur_len0 = vlib_buffer_length_in_chain (vm, p0);
+
+  len_diff0 = cur_len0 - ip_len0;
+
+  error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;
+
+  if (PREDICT_FALSE (error0 != IP4_ERROR_NONE))
+    {
+      if (error0 == IP4_ERROR_TIME_EXPIRED)
+	{
+	  icmp4_error_set_vnet_buffer (p0, ICMP4_time_exceeded,
+				       ICMP4_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next0 = IP4_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	*next0 = error0 != IP4_ERROR_OPTIONS ?
+	  IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
+    }
+
+  p0->error = error_node->errors[error0];
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
+
+#endif
diff --git a/src/vnet/ip/ip6_input.c b/src/vnet/ip/ip6_input.c
index ffdc4727660..3b38d347e6e 100644
--- a/src/vnet/ip/ip6_input.c
+++ b/src/vnet/ip/ip6_input.c
@@ -37,7 +37,7 @@
  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
-#include <vnet/ip/ip.h>
+#include <vnet/ip/ip6_input.h>
 #include <vnet/ethernet/ethernet.h>
 #include <vnet/ppp/ppp.h>
 #include <vnet/hdlc/hdlc.h>
@@ -60,15 +60,6 @@ format_ip6_input_trace (u8 * s, va_list * va)
   return s;
 }
 
-typedef enum
-{
-  IP6_INPUT_NEXT_DROP,
-  IP6_INPUT_NEXT_LOOKUP,
-  IP6_INPUT_NEXT_LOOKUP_MULTICAST,
-  IP6_INPUT_NEXT_ICMP_ERROR,
-  IP6_INPUT_N_NEXT,
-} ip6_input_next_t;
-
 /* Validate IP v6 packets and pass them either to forwarding code
    or drop exception packets. */
 static uword
@@ -108,7 +99,7 @@ ip6_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 	  ip6_header_t *ip0, *ip1;
 	  u32 pi0, sw_if_index0, next0 = 0;
 	  u32 pi1, sw_if_index1, next1 = 0;
-	  u8 error0, error1, arc0, arc1;
+	  u8 arc0, arc1;
 
 	  /* Prefetch next iteration. */
 	  {
@@ -173,65 +164,8 @@ ip6_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 
 	  vlib_increment_simple_counter (cm, thread_index, sw_if_index0, 1);
 	  vlib_increment_simple_counter (cm, thread_index, sw_if_index1, 1);
-
-	  error0 = error1 = IP6_ERROR_NONE;
-
-	  /* Version != 6?  Drop it. */
-	  error0 =
-	    (clib_net_to_host_u32
-	     (ip0->ip_version_traffic_class_and_flow_label) >> 28) !=
-	    6 ? IP6_ERROR_VERSION : error0;
-	  error1 =
-	    (clib_net_to_host_u32
-	     (ip1->ip_version_traffic_class_and_flow_label) >> 28) !=
-	    6 ? IP6_ERROR_VERSION : error1;
-
-	  /* hop limit < 1? Drop it.  for link-local broadcast packets,
-	   * like dhcpv6 packets from client has hop-limit 1, which should not
-	   * be dropped.
-	   */
-	  error0 = ip0->hop_limit < 1 ? IP6_ERROR_TIME_EXPIRED : error0;
-	  error1 = ip1->hop_limit < 1 ? IP6_ERROR_TIME_EXPIRED : error1;
-
-	  /* L2 length must be at least minimal IP header. */
-	  error0 =
-	    p0->current_length <
-	    sizeof (ip0[0]) ? IP6_ERROR_TOO_SHORT : error0;
-	  error1 =
-	    p1->current_length <
-	    sizeof (ip1[0]) ? IP6_ERROR_TOO_SHORT : error1;
-
-	  if (PREDICT_FALSE (error0 != IP6_ERROR_NONE))
-	    {
-	      if (error0 == IP6_ERROR_TIME_EXPIRED)
-		{
-		  icmp6_error_set_vnet_buffer (p0, ICMP6_time_exceeded,
-					       ICMP6_time_exceeded_ttl_exceeded_in_transit,
-					       0);
-		  next0 = IP6_INPUT_NEXT_ICMP_ERROR;
-		}
-	      else
-		{
-		  next0 = IP6_INPUT_NEXT_DROP;
-		}
-	    }
-	  if (PREDICT_FALSE (error1 != IP6_ERROR_NONE))
-	    {
-	      if (error1 == IP6_ERROR_TIME_EXPIRED)
-		{
-		  icmp6_error_set_vnet_buffer (p1, ICMP6_time_exceeded,
-					       ICMP6_time_exceeded_ttl_exceeded_in_transit,
-					       0);
-		  next1 = IP6_INPUT_NEXT_ICMP_ERROR;
-		}
-	      else
-		{
-		  next1 = IP6_INPUT_NEXT_DROP;
-		}
-	    }
-
-	  p0->error = error_node->errors[error0];
-	  p1->error = error_node->errors[error1];
+	  ip6_input_check_x2 (vm, error_node,
+			      p0, p1, ip0, ip1, &next0, &next1);
 
 	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
 					   to_next, n_left_to_next,
@@ -243,7 +177,7 @@ ip6_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 	  vlib_buffer_t *p0;
 	  ip6_header_t *ip0;
 	  u32 pi0, sw_if_index0, next0 = 0;
-	  u8 error0, arc0;
+	  u8 arc0;
 
 	  pi0 = from[0];
 	  to_next[0] = pi0;
@@ -271,40 +205,7 @@ ip6_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 	  vnet_feature_arc_start (arc0, sw_if_index0, &next0, p0);
 
 	  vlib_increment_simple_counter (cm, thread_index, sw_if_index0, 1);
-	  error0 = IP6_ERROR_NONE;
-
-	  /* Version != 6?  Drop it. */
-	  error0 =
-	    (clib_net_to_host_u32
-	     (ip0->ip_version_traffic_class_and_flow_label) >> 28) !=
-	    6 ? IP6_ERROR_VERSION : error0;
-
-	  /* hop limit < 1? Drop it. for link-local broadcast packets,
-	   * like dhcpv6 packets from client has hop-limit 1, which should not
-	   * be dropped.
-	   */
-	  error0 = ip0->hop_limit < 1 ? IP6_ERROR_TIME_EXPIRED : error0;
-
-	  /* L2 length must be at least minimal IP header. */
-	  error0 =
-	    p0->current_length <
-	    sizeof (ip0[0]) ? IP6_ERROR_TOO_SHORT : error0;
-
-	  if (PREDICT_FALSE (error0 != IP6_ERROR_NONE))
-	    {
-	      if (error0 == IP6_ERROR_TIME_EXPIRED)
-		{
-		  icmp6_error_set_vnet_buffer (p0, ICMP6_time_exceeded,
-					       ICMP6_time_exceeded_ttl_exceeded_in_transit,
-					       0);
-		  next0 = IP6_INPUT_NEXT_ICMP_ERROR;
-		}
-	      else
-		{
-		  next0 = IP6_INPUT_NEXT_DROP;
-		}
-	    }
-	  p0->error = error_node->errors[error0];
+	  ip6_input_check_x1 (vm, error_node, p0, ip0, &next0);
 
 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
@@ -317,7 +218,7 @@ ip6_input (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
   return frame->n_vectors;
 }
 
-static char *ip6_error_strings[] = {
+char *ip6_error_strings[] = {
 #define _(sym,string) string,
   foreach_ip6_error
 #undef _
diff --git a/src/vnet/ip/ip6_input.h b/src/vnet/ip/ip6_input.h
new file mode 100644
index 00000000000..4c0d78459b1
--- /dev/null
+++ b/src/vnet/ip/ip6_input.h
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * ip/ip6_input.c: IP v6 input node
+ *
+ * Copyright (c) 2008 Eliot Dresselhaus
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef included_ip6_input_h
+#define included_ip6_input_h
+
+#include <vnet/ip/ip.h>
+
+extern char *ip6_error_strings[];
+
+typedef enum
+{
+  IP6_INPUT_NEXT_DROP,
+  IP6_INPUT_NEXT_LOOKUP,
+  IP6_INPUT_NEXT_LOOKUP_MULTICAST,
+  IP6_INPUT_NEXT_ICMP_ERROR,
+  IP6_INPUT_N_NEXT,
+} ip6_input_next_t;
+
+always_inline void
+ip6_input_check_x2 (vlib_main_t * vm,
+		    vlib_node_runtime_t * error_node,
+		    vlib_buffer_t * p0, vlib_buffer_t * p1,
+		    ip6_header_t * ip0, ip6_header_t * ip1,
+		    u32 * next0, u32 * next1)
+{
+  u8 error0, error1;
+
+  error0 = error1 = IP6_ERROR_NONE;
+
+  /* Version != 6?  Drop it. */
+  error0 =
+    (clib_net_to_host_u32
+     (ip0->ip_version_traffic_class_and_flow_label) >> 28) !=
+    6 ? IP6_ERROR_VERSION : error0;
+  error1 =
+    (clib_net_to_host_u32
+     (ip1->ip_version_traffic_class_and_flow_label) >> 28) !=
+    6 ? IP6_ERROR_VERSION : error1;
+
+  /* hop limit < 1? Drop it.  for link-local broadcast packets,
+   * like dhcpv6 packets from client has hop-limit 1, which should not
+   * be dropped.
+   */
+  error0 = ip0->hop_limit < 1 ? IP6_ERROR_TIME_EXPIRED : error0;
+  error1 = ip1->hop_limit < 1 ? IP6_ERROR_TIME_EXPIRED : error1;
+
+  /* L2 length must be at least minimal IP header. */
+  error0 =
+    p0->current_length < sizeof (ip0[0]) ? IP6_ERROR_TOO_SHORT : error0;
+  error1 =
+    p1->current_length < sizeof (ip1[0]) ? IP6_ERROR_TOO_SHORT : error1;
+
+  if (PREDICT_FALSE (error0 != IP6_ERROR_NONE))
+    {
+      if (error0 == IP6_ERROR_TIME_EXPIRED)
+	{
+	  icmp6_error_set_vnet_buffer (p0, ICMP6_time_exceeded,
+				       ICMP6_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next0 = IP6_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	{
+	  *next0 = IP6_INPUT_NEXT_DROP;
+	}
+    }
+  if (PREDICT_FALSE (error1 != IP6_ERROR_NONE))
+    {
+      if (error1 == IP6_ERROR_TIME_EXPIRED)
+	{
+	  icmp6_error_set_vnet_buffer (p1, ICMP6_time_exceeded,
+				       ICMP6_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next1 = IP6_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	{
+	  *next1 = IP6_INPUT_NEXT_DROP;
+	}
+    }
+}
+
+always_inline void
+ip6_input_check_x1 (vlib_main_t * vm,
+		    vlib_node_runtime_t * error_node,
+		    vlib_buffer_t * p0, ip6_header_t * ip0, u32 * next0)
+{
+  u8 error0;
+
+  error0 = IP6_ERROR_NONE;
+
+  /* Version != 6?  Drop it. */
+  error0 =
+    (clib_net_to_host_u32
+     (ip0->ip_version_traffic_class_and_flow_label) >> 28) !=
+    6 ? IP6_ERROR_VERSION : error0;
+
+  /* hop limit < 1? Drop it.  for link-local broadcast packets,
+   * like dhcpv6 packets from client has hop-limit 1, which should not
+   * be dropped.
+   */
+  error0 = ip0->hop_limit < 1 ? IP6_ERROR_TIME_EXPIRED : error0;
+
+  /* L2 length must be at least minimal IP header. */
+  error0 =
+    p0->current_length < sizeof (ip0[0]) ? IP6_ERROR_TOO_SHORT : error0;
+
+  if (PREDICT_FALSE (error0 != IP6_ERROR_NONE))
+    {
+      if (error0 == IP6_ERROR_TIME_EXPIRED)
+	{
+	  icmp6_error_set_vnet_buffer (p0, ICMP6_time_exceeded,
+				       ICMP6_time_exceeded_ttl_exceeded_in_transit,
+				       0);
+	  *next0 = IP6_INPUT_NEXT_ICMP_ERROR;
+	}
+      else
+	{
+	  *next0 = IP6_INPUT_NEXT_DROP;
+	}
+    }
+}
+
+#endif
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */