src/vnet/ip/ip_frag.c - fdio/vpp - Gitiles

 /*---------------------------------------------------------------------------
  * Copyright (c) 2009-2014 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.
  *---------------------------------------------------------------------------
  */
 /*
  * IPv4 Fragmentation Node
  *
  *
  */

 #include "ip_frag.h"

 #include <vnet/ip/ip.h>


 typedef struct
 {
   u8 ipv6;
   u16 mtu;
   u8 next;
   u16 n_fragments;
 } ip_frag_trace_t;

 static u8 *
 format_ip_frag_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   ip_frag_trace_t *t = va_arg (*args, ip_frag_trace_t *);
   s = format (s, "IPv%s mtu: %u fragments: %u",
 	      t->ipv6 ? "6" : "4", t->mtu, t->n_fragments);
   return s;
 }

 static u32 running_fragment_id;

 static void
 frag_set_sw_if_index (vlib_buffer_t * to, vlib_buffer_t * from)
 {
   vnet_buffer (to)->sw_if_index[VLIB_RX] =
     vnet_buffer (from)->sw_if_index[VLIB_RX];
   vnet_buffer (to)->sw_if_index[VLIB_TX] =
     vnet_buffer (from)->sw_if_index[VLIB_TX];

   /* Copy adj_index in case DPO based node is sending for the
    * fragmentation, the packet would be sent back to the proper
    * DPO next node and Index
    */
   vnet_buffer (to)->ip.adj_index[VLIB_RX] =
     vnet_buffer (from)->ip.adj_index[VLIB_RX];
   vnet_buffer (to)->ip.adj_index[VLIB_TX] =
     vnet_buffer (from)->ip.adj_index[VLIB_TX];

   /* Copy QoS Bits */
   if (PREDICT_TRUE (from->flags & VNET_BUFFER_F_QOS_DATA_VALID))
     {
       vnet_buffer2 (to)->qos = vnet_buffer2 (from)->qos;
       to->flags |= VNET_BUFFER_F_QOS_DATA_VALID;
     }
 }

 static vlib_buffer_t *
 frag_buffer_alloc (vlib_buffer_t * org_b, u32 * bi)
 {
   vlib_main_t *vm = vlib_get_main ();
   if (vlib_buffer_alloc (vm, bi, 1) != 1)
     return 0;

   vlib_buffer_t *b = vlib_get_buffer (vm, *bi);
   VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   vlib_buffer_copy_trace_flag (vm, org_b, *bi);

   return b;
 }

 /*
  * Limitation: Does follow buffer chains in the packet to fragment,
  * but does not generate buffer chains. I.e. a fragment is always
  * contained with in a single buffer and limited to the max buffer
  * size.
  */
 void
 ip4_frag_do_fragment (vlib_main_t * vm, u32 from_bi, u32 ** buffer,
 		      ip_frag_error_t * error)
 {
   vlib_buffer_t *from_b;
   ip4_header_t *ip4;
   u16 mtu, len, max, rem, ip_frag_id, ip_frag_offset;
   u8 *org_from_packet, more;

   from_b = vlib_get_buffer (vm, from_bi);
   mtu = vnet_buffer (from_b)->ip_frag.mtu;
   org_from_packet = vlib_buffer_get_current (from_b);
   ip4 = (ip4_header_t *) vlib_buffer_get_current (from_b);

   rem = clib_net_to_host_u16 (ip4->length) - sizeof (ip4_header_t);
   max =
     (clib_min (mtu, vlib_bufer_get_default_size (vm)) -
      sizeof (ip4_header_t)) & ~0x7;

   if (rem >
       (vlib_buffer_length_in_chain (vm, from_b) - sizeof (ip4_header_t)))
     {
       *error = IP_FRAG_ERROR_MALFORMED;
       return;
     }

   if (mtu < sizeof (ip4_header_t))
     {
       *error = IP_FRAG_ERROR_CANT_FRAGMENT_HEADER;
       return;
     }

   if (ip4->flags_and_fragment_offset &
       clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT))
     {
       *error = IP_FRAG_ERROR_DONT_FRAGMENT_SET;
       return;
     }

   if (ip4_is_fragment (ip4))
     {
       ip_frag_id = ip4->fragment_id;
       ip_frag_offset = ip4_get_fragment_offset (ip4);
       more =
 	!(!(ip4->flags_and_fragment_offset &
 	    clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS)));
     }
   else
     {
       ip_frag_id = (++running_fragment_id);
       ip_frag_offset = 0;
       more = 0;
     }

   u8 *from_data = (void *) (ip4 + 1);
   vlib_buffer_t *org_from_b = from_b;
   u16 fo = 0;
   u16 left_in_from_buffer = from_b->current_length - sizeof (ip4_header_t);
   u16 ptr = 0;

   /* Do the actual fragmentation */
   while (rem)
     {
       u32 to_bi;
       vlib_buffer_t *to_b;
       ip4_header_t *to_ip4;
       u8 *to_data;

       len = (rem > max ? max : rem);
       if (len != rem)		/* Last fragment does not need to divisible by 8 */
 	len &= ~0x7;
       if ((to_b = frag_buffer_alloc (org_from_b, &to_bi)) == 0)
 	{
 	  *error = IP_FRAG_ERROR_MEMORY;
 	  return;
 	}
       vec_add1 (*buffer, to_bi);
       frag_set_sw_if_index (to_b, org_from_b);

       /* Copy ip4 header */
       clib_memcpy_fast (to_b->data, org_from_packet, sizeof (ip4_header_t));
       to_ip4 = vlib_buffer_get_current (to_b);
       to_data = (void *) (to_ip4 + 1);

       /* Spin through from buffers filling up the to buffer */
       u16 left_in_to_buffer = len, to_ptr = 0;
       while (1)
 	{
 	  u16 bytes_to_copy;

 	  /* Figure out how many bytes we can safely copy */
 	  bytes_to_copy = left_in_to_buffer <= left_in_from_buffer ?
 	    left_in_to_buffer : left_in_from_buffer;
 	  clib_memcpy_fast (to_data + to_ptr, from_data + ptr, bytes_to_copy);
 	  left_in_to_buffer -= bytes_to_copy;
 	  ptr += bytes_to_copy;
 	  left_in_from_buffer -= bytes_to_copy;
 	  if (left_in_to_buffer == 0)
 	    break;

 	  ASSERT (left_in_from_buffer <= 0);
 	  /* Move buffer */
 	  if (!(from_b->flags & VLIB_BUFFER_NEXT_PRESENT))
 	    {
 	      *error = IP_FRAG_ERROR_MALFORMED;
 	      return;
 	    }
 	  from_b = vlib_get_buffer (vm, from_b->next_buffer);
 	  from_data = (u8 *) vlib_buffer_get_current (from_b);
 	  ptr = 0;
 	  left_in_from_buffer = from_b->current_length;
 	  to_ptr += bytes_to_copy;
 	}

       to_b->current_length = len + sizeof (ip4_header_t);

       to_ip4->fragment_id = ip_frag_id;
       to_ip4->flags_and_fragment_offset =
 	clib_host_to_net_u16 ((fo >> 3) + ip_frag_offset);
       to_ip4->flags_and_fragment_offset |=
 	clib_host_to_net_u16 (((len != rem) || more) << 13);
       to_ip4->length = clib_host_to_net_u16 (len + sizeof (ip4_header_t));
       to_ip4->checksum = ip4_header_checksum (to_ip4);

       if (vnet_buffer (org_from_b)->ip_frag.flags & IP_FRAG_FLAG_IP4_HEADER)
 	{
 	  /* Encapsulating ipv4 header */
 	  ip4_header_t *encap_header4 =
 	    (ip4_header_t *) vlib_buffer_get_current (to_b);
 	  encap_header4->length = clib_host_to_net_u16 (to_b->current_length);
 	  encap_header4->checksum = ip4_header_checksum (encap_header4);
 	}
       else if (vnet_buffer (org_from_b)->
 	       ip_frag.flags & IP_FRAG_FLAG_IP6_HEADER)
 	{
 	  /* Encapsulating ipv6 header */
 	  ip6_header_t *encap_header6 =
 	    (ip6_header_t *) vlib_buffer_get_current (to_b);
 	  encap_header6->payload_length =
 	    clib_host_to_net_u16 (to_b->current_length -
 				  sizeof (*encap_header6));
 	}
       rem -= len;
       fo += len;
     }
 }

 void
 ip_frag_set_vnet_buffer (vlib_buffer_t * b, u16 mtu, u8 next_index, u8 flags)
 {
   vnet_buffer (b)->ip_frag.mtu = mtu;
   vnet_buffer (b)->ip_frag.next_index = next_index;
   vnet_buffer (b)->ip_frag.flags = flags;
 }


 static inline uword
 frag_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 		  vlib_frame_t * frame, u32 node_index, bool is_ip6)
 {
   u32 n_left_from, *from, next_index, *to_next, n_left_to_next;
   vlib_node_runtime_t *error_node = vlib_node_get_runtime (vm, node_index);
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
   next_index = node->cached_next_index;
   u32 frag_sent = 0, small_packets = 0;
   u32 *buffer = 0;

   while (n_left_from > 0)
     {
       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

       while (n_left_from > 0 && n_left_to_next > 0)
 	{
 	  u32 pi0, *frag_from, frag_left;
 	  vlib_buffer_t *p0;
 	  ip_frag_error_t error0;
 	  int next0;

 	  /*
 	   * Note: The packet is not enqueued now. It is instead put
 	   * in a vector where other fragments will be put as well.
 	   */
 	  pi0 = from[0];
 	  from += 1;
 	  n_left_from -= 1;
 	  error0 = IP_FRAG_ERROR_NONE;

 	  p0 = vlib_get_buffer (vm, pi0);
 	  if (is_ip6)
 	    ip6_frag_do_fragment (vm, pi0, &buffer, &error0);
 	  else
 	    ip4_frag_do_fragment (vm, pi0, &buffer, &error0);

 	  if (PREDICT_FALSE (p0->flags & VLIB_BUFFER_IS_TRACED))
 	    {
 	      ip_frag_trace_t *tr =
 		vlib_add_trace (vm, node, p0, sizeof (*tr));
 	      tr->mtu = vnet_buffer (p0)->ip_frag.mtu;
 	      tr->ipv6 = is_ip6 ? 1 : 0;
 	      tr->n_fragments = vec_len (buffer);
 	      tr->next = vnet_buffer (p0)->ip_frag.next_index;
 	    }

 	  if (!is_ip6 && error0 == IP_FRAG_ERROR_DONT_FRAGMENT_SET)
 	    {
 	      icmp4_error_set_vnet_buffer (p0, ICMP4_destination_unreachable,
 					   ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
 					   vnet_buffer (p0)->ip_frag.mtu);
 	      next0 = IP4_FRAG_NEXT_ICMP_ERROR;
 	    }
 	  else
 	    {
 	      if (is_ip6)
 		next0 =
 		  (error0 ==
 		   IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
 		  ip_frag.next_index : IP6_FRAG_NEXT_DROP;
 	      else
 		next0 =
 		  (error0 ==
 		   IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
 		  ip_frag.next_index : IP4_FRAG_NEXT_DROP;
 	    }

 	  if (error0 == IP_FRAG_ERROR_NONE)
 	    {
 	      /* Free original buffer chain */
 	      frag_sent += vec_len (buffer);
 	      small_packets += (vec_len (buffer) == 1);
 	      vlib_buffer_free_one (vm, pi0);	/* Free original packet */
 	    }
 	  else
 	    {
 	      vlib_error_count (vm, node_index, error0, 1);
 	      vec_add1 (buffer, pi0);	/* Get rid of the original buffer */
 	    }

 	  /* Send fragments that were added in the frame */
 	  frag_from = buffer;
 	  frag_left = vec_len (buffer);

 	  while (frag_left > 0)
 	    {
 	      while (frag_left > 0 && n_left_to_next > 0)
 		{
 		  u32 i;
 		  i = to_next[0] = frag_from[0];
 		  frag_from += 1;
 		  frag_left -= 1;
 		  to_next += 1;
 		  n_left_to_next -= 1;

 		  vlib_get_buffer (vm, i)->error = error_node->errors[error0];
 		  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 						   to_next, n_left_to_next, i,
 						   next0);
 		}
 	      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
 	      vlib_get_next_frame (vm, node, next_index, to_next,
 				   n_left_to_next);
 	    }
 	  vec_reset_length (buffer);
 	}
       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }
   vec_free (buffer);

   vlib_node_increment_counter (vm, node_index,
 			       IP_FRAG_ERROR_FRAGMENT_SENT, frag_sent);
   vlib_node_increment_counter (vm, node_index,
 			       IP_FRAG_ERROR_SMALL_PACKET, small_packets);

   return frame->n_vectors;
 }


 static uword
 ip4_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   return frag_node_inline (vm, node, frame, ip4_frag_node.index,
 			   0 /* is_ip6 */ );
 }

 static uword
 ip6_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   return frag_node_inline (vm, node, frame, ip6_frag_node.index,
 			   1 /* is_ip6 */ );
 }

 /*
  * Fragments the packet given in from_bi. Fragments are returned in the buffer vector.
  * Caller must ensure the original packet is freed.
  */
 void
 ip6_frag_do_fragment (vlib_main_t * vm, u32 from_bi, u32 ** buffer,
 		      ip_frag_error_t * error)
 {
   vlib_buffer_t *from_b;
   ip6_header_t *ip6;
   u16 mtu, len, max, rem, ip_frag_id;

   from_b = vlib_get_buffer (vm, from_bi);
   mtu = vnet_buffer (from_b)->ip_frag.mtu;
   ip6 = (ip6_header_t *) vlib_buffer_get_current (from_b);

   rem = clib_net_to_host_u16 (ip6->payload_length);
   max = (mtu - sizeof (ip6_header_t) - sizeof (ip6_frag_hdr_t)) & ~0x7;	// TODO: Is max correct??

   if (rem >
       (vlib_buffer_length_in_chain (vm, from_b) - sizeof (ip6_header_t)))
     {
       *error = IP_FRAG_ERROR_MALFORMED;
       return;
     }

   /* TODO: Look through header chain for fragmentation header */
   if (ip6->protocol == IP_PROTOCOL_IPV6_FRAGMENTATION)
     {
       *error = IP_FRAG_ERROR_MALFORMED;
       return;
     }

   u8 *from_data = (void *) (ip6 + 1);
   vlib_buffer_t *org_from_b = from_b;
   u16 fo = 0;
   u16 left_in_from_buffer = from_b->current_length - sizeof (ip6_header_t);
   u16 ptr = 0;

   ip_frag_id = ++running_fragment_id;	// Fix

   /* Do the actual fragmentation */
   while (rem)
     {
       u32 to_bi;
       vlib_buffer_t *to_b;
       ip6_header_t *to_ip6;
       ip6_frag_hdr_t *to_frag_hdr;
       u8 *to_data;

       len =
 	(rem >
 	 (mtu - sizeof (ip6_header_t) - sizeof (ip6_frag_hdr_t)) ? max : rem);
       if (len != rem)		/* Last fragment does not need to divisible by 8 */
 	len &= ~0x7;
       if ((to_b = frag_buffer_alloc (org_from_b, &to_bi)) == 0)
 	{
 	  *error = IP_FRAG_ERROR_MEMORY;
 	  return;
 	}
       vec_add1 (*buffer, to_bi);
       frag_set_sw_if_index (to_b, org_from_b);

       /* Copy ip6 header */
       clib_memcpy_fast (to_b->data, ip6, sizeof (ip6_header_t));
       to_ip6 = vlib_buffer_get_current (to_b);
       to_frag_hdr = (ip6_frag_hdr_t *) (to_ip6 + 1);
       to_data = (void *) (to_frag_hdr + 1);

       /* Spin through from buffers filling up the to buffer */
       u16 left_in_to_buffer = len, to_ptr = 0;
       while (1)
 	{
 	  u16 bytes_to_copy;

 	  /* Figure out how many bytes we can safely copy */
 	  bytes_to_copy = left_in_to_buffer <= left_in_from_buffer ?
 	    left_in_to_buffer : left_in_from_buffer;
 	  clib_memcpy_fast (to_data + to_ptr, from_data + ptr, bytes_to_copy);
 	  left_in_to_buffer -= bytes_to_copy;
 	  ptr += bytes_to_copy;
 	  left_in_from_buffer -= bytes_to_copy;
 	  if (left_in_to_buffer == 0)
 	    break;

 	  ASSERT (left_in_from_buffer <= 0);
 	  /* Move buffer */
 	  if (!(from_b->flags & VLIB_BUFFER_NEXT_PRESENT))
 	    {
 	      *error = IP_FRAG_ERROR_MALFORMED;
 	      return;
 	    }
 	  from_b = vlib_get_buffer (vm, from_b->next_buffer);
 	  from_data = (u8 *) vlib_buffer_get_current (from_b);
 	  ptr = 0;
 	  left_in_from_buffer = from_b->current_length;
 	  to_ptr += bytes_to_copy;
 	}

       to_b->current_length =
 	len + sizeof (ip6_header_t) + sizeof (ip6_frag_hdr_t);
       to_ip6->payload_length =
 	clib_host_to_net_u16 (len + sizeof (ip6_frag_hdr_t));
       to_ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
       to_frag_hdr->fragment_offset_and_more =
 	ip6_frag_hdr_offset_and_more ((fo >> 3), len != rem);
       to_frag_hdr->identification = ip_frag_id;
       to_frag_hdr->next_hdr = ip6->protocol;
       to_frag_hdr->rsv = 0;

       rem -= len;
       fo += len;
     }
 }

 static char *ip4_frag_error_strings[] = {
 #define _(sym,string) string,
   foreach_ip_frag_error
 #undef _
 };

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (ip4_frag_node) = {
   .function = ip4_frag,
   .name = IP4_FRAG_NODE_NAME,
   .vector_size = sizeof (u32),
   .format_trace = format_ip_frag_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,

   .n_errors = IP_FRAG_N_ERROR,
   .error_strings = ip4_frag_error_strings,

   .n_next_nodes = IP4_FRAG_N_NEXT,
   .next_nodes = {
     [IP4_FRAG_NEXT_IP4_REWRITE] = "ip4-rewrite",
     [IP4_FRAG_NEXT_IP4_LOOKUP] = "ip4-lookup",
     [IP4_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
     [IP4_FRAG_NEXT_ICMP_ERROR] = "ip4-icmp-error",
     [IP4_FRAG_NEXT_DROP] = "ip4-drop"
   },
 };
 /* *INDENT-ON* */

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (ip6_frag_node) = {
   .function = ip6_frag,
   .name = IP6_FRAG_NODE_NAME,
   .vector_size = sizeof (u32),
   .format_trace = format_ip_frag_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,

   .n_errors = IP_FRAG_N_ERROR,
   .error_strings = ip4_frag_error_strings,

   .n_next_nodes = IP6_FRAG_N_NEXT,
   .next_nodes = {
     [IP6_FRAG_NEXT_IP6_REWRITE] = "ip6-rewrite",
     [IP6_FRAG_NEXT_IP4_LOOKUP] = "ip4-lookup",
     [IP6_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
     [IP6_FRAG_NEXT_DROP] = "ip6-drop"
   },
 };
 /* *INDENT-ON* */

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*---------------------------------------------------------------------------
	* Copyright (c) 2009-2014 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.
	*---------------------------------------------------------------------------
	*/
	/*
	* IPv4 Fragmentation Node
	*
	*
	*/

	#include "ip_frag.h"

	#include <vnet/ip/ip.h>


	typedef struct
	{
	u8 ipv6;
	u16 mtu;
	u8 next;
	u16 n_fragments;
	} ip_frag_trace_t;

	static u8 *
	format_ip_frag_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	ip_frag_trace_t t = va_arg (args, ip_frag_trace_t *);
	s = format (s, "IPv%s mtu: %u fragments: %u",
	t->ipv6 ? "6" : "4", t->mtu, t->n_fragments);
	return s;
	}

	static u32 running_fragment_id;

	static void
	frag_set_sw_if_index (vlib_buffer_t * to, vlib_buffer_t * from)
	{
	vnet_buffer (to)->sw_if_index[VLIB_RX] =
	vnet_buffer (from)->sw_if_index[VLIB_RX];
	vnet_buffer (to)->sw_if_index[VLIB_TX] =
	vnet_buffer (from)->sw_if_index[VLIB_TX];

	/* Copy adj_index in case DPO based node is sending for the
	* fragmentation, the packet would be sent back to the proper
	* DPO next node and Index
	*/
	vnet_buffer (to)->ip.adj_index[VLIB_RX] =
	vnet_buffer (from)->ip.adj_index[VLIB_RX];
	vnet_buffer (to)->ip.adj_index[VLIB_TX] =
	vnet_buffer (from)->ip.adj_index[VLIB_TX];

	/* Copy QoS Bits */
	if (PREDICT_TRUE (from->flags & VNET_BUFFER_F_QOS_DATA_VALID))
	{
	vnet_buffer2 (to)->qos = vnet_buffer2 (from)->qos;
	to->flags \|= VNET_BUFFER_F_QOS_DATA_VALID;
	}
	}

	static vlib_buffer_t *
	frag_buffer_alloc (vlib_buffer_t * org_b, u32 * bi)
	{
	vlib_main_t *vm = vlib_get_main ();
	if (vlib_buffer_alloc (vm, bi, 1) != 1)
	return 0;

	vlib_buffer_t b = vlib_get_buffer (vm, bi);
	VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
	vlib_buffer_copy_trace_flag (vm, org_b, *bi);

	return b;
	}

	/*
	* Limitation: Does follow buffer chains in the packet to fragment,
	* but does not generate buffer chains. I.e. a fragment is always
	* contained with in a single buffer and limited to the max buffer
	* size.
	*/
	void
	ip4_frag_do_fragment (vlib_main_t * vm, u32 from_bi, u32 ** buffer,
	ip_frag_error_t * error)
	{
	vlib_buffer_t *from_b;
	ip4_header_t *ip4;
	u16 mtu, len, max, rem, ip_frag_id, ip_frag_offset;
	u8 *org_from_packet, more;

	from_b = vlib_get_buffer (vm, from_bi);
	mtu = vnet_buffer (from_b)->ip_frag.mtu;
	org_from_packet = vlib_buffer_get_current (from_b);
	ip4 = (ip4_header_t *) vlib_buffer_get_current (from_b);

	rem = clib_net_to_host_u16 (ip4->length) - sizeof (ip4_header_t);
	max =
	(clib_min (mtu, vlib_bufer_get_default_size (vm)) -
	sizeof (ip4_header_t)) & ~0x7;

	if (rem >
	(vlib_buffer_length_in_chain (vm, from_b) - sizeof (ip4_header_t)))
	{
	*error = IP_FRAG_ERROR_MALFORMED;
	return;
	}

	if (mtu < sizeof (ip4_header_t))
	{
	*error = IP_FRAG_ERROR_CANT_FRAGMENT_HEADER;
	return;
	}

	if (ip4->flags_and_fragment_offset &
	clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT))
	{
	*error = IP_FRAG_ERROR_DONT_FRAGMENT_SET;
	return;
	}

	if (ip4_is_fragment (ip4))
	{
	ip_frag_id = ip4->fragment_id;
	ip_frag_offset = ip4_get_fragment_offset (ip4);
	more =
	!(!(ip4->flags_and_fragment_offset &
	clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS)));
	}
	else
	{
	ip_frag_id = (++running_fragment_id);
	ip_frag_offset = 0;
	more = 0;
	}

	u8 from_data = (void ) (ip4 + 1);
	vlib_buffer_t *org_from_b = from_b;
	u16 fo = 0;
	u16 left_in_from_buffer = from_b->current_length - sizeof (ip4_header_t);
	u16 ptr = 0;

	/* Do the actual fragmentation */
	while (rem)
	{
	u32 to_bi;
	vlib_buffer_t *to_b;
	ip4_header_t *to_ip4;
	u8 *to_data;

	len = (rem > max ? max : rem);
	if (len != rem) /* Last fragment does not need to divisible by 8 */
	len &= ~0x7;
	if ((to_b = frag_buffer_alloc (org_from_b, &to_bi)) == 0)
	{
	*error = IP_FRAG_ERROR_MEMORY;
	return;
	}
	vec_add1 (*buffer, to_bi);
	frag_set_sw_if_index (to_b, org_from_b);

	/* Copy ip4 header */
	clib_memcpy_fast (to_b->data, org_from_packet, sizeof (ip4_header_t));
	to_ip4 = vlib_buffer_get_current (to_b);
	to_data = (void *) (to_ip4 + 1);

	/* Spin through from buffers filling up the to buffer */
	u16 left_in_to_buffer = len, to_ptr = 0;
	while (1)
	{
	u16 bytes_to_copy;

	/* Figure out how many bytes we can safely copy */
	bytes_to_copy = left_in_to_buffer <= left_in_from_buffer ?
	left_in_to_buffer : left_in_from_buffer;
	clib_memcpy_fast (to_data + to_ptr, from_data + ptr, bytes_to_copy);
	left_in_to_buffer -= bytes_to_copy;
	ptr += bytes_to_copy;
	left_in_from_buffer -= bytes_to_copy;
	if (left_in_to_buffer == 0)
	break;

	ASSERT (left_in_from_buffer <= 0);
	/* Move buffer */
	if (!(from_b->flags & VLIB_BUFFER_NEXT_PRESENT))
	{
	*error = IP_FRAG_ERROR_MALFORMED;
	return;
	}
	from_b = vlib_get_buffer (vm, from_b->next_buffer);
	from_data = (u8 *) vlib_buffer_get_current (from_b);
	ptr = 0;
	left_in_from_buffer = from_b->current_length;
	to_ptr += bytes_to_copy;
	}

	to_b->current_length = len + sizeof (ip4_header_t);

	to_ip4->fragment_id = ip_frag_id;
	to_ip4->flags_and_fragment_offset =
	clib_host_to_net_u16 ((fo >> 3) + ip_frag_offset);
	to_ip4->flags_and_fragment_offset \|=
	clib_host_to_net_u16 (((len != rem) \|\| more) << 13);
	to_ip4->length = clib_host_to_net_u16 (len + sizeof (ip4_header_t));
	to_ip4->checksum = ip4_header_checksum (to_ip4);

	if (vnet_buffer (org_from_b)->ip_frag.flags & IP_FRAG_FLAG_IP4_HEADER)
	{
	/* Encapsulating ipv4 header */
	ip4_header_t *encap_header4 =
	(ip4_header_t *) vlib_buffer_get_current (to_b);
	encap_header4->length = clib_host_to_net_u16 (to_b->current_length);
	encap_header4->checksum = ip4_header_checksum (encap_header4);
	}
	else if (vnet_buffer (org_from_b)->
	ip_frag.flags & IP_FRAG_FLAG_IP6_HEADER)
	{
	/* Encapsulating ipv6 header */
	ip6_header_t *encap_header6 =
	(ip6_header_t *) vlib_buffer_get_current (to_b);
	encap_header6->payload_length =
	clib_host_to_net_u16 (to_b->current_length -
	sizeof (*encap_header6));
	}
	rem -= len;
	fo += len;
	}
	}

	void
	ip_frag_set_vnet_buffer (vlib_buffer_t * b, u16 mtu, u8 next_index, u8 flags)
	{
	vnet_buffer (b)->ip_frag.mtu = mtu;
	vnet_buffer (b)->ip_frag.next_index = next_index;
	vnet_buffer (b)->ip_frag.flags = flags;
	}


	static inline uword
	frag_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
	vlib_frame_t * frame, u32 node_index, bool is_ip6)
	{
	u32 n_left_from, from, next_index, to_next, n_left_to_next;
	vlib_node_runtime_t *error_node = vlib_node_get_runtime (vm, node_index);
	from = vlib_frame_vector_args (frame);
	n_left_from = frame->n_vectors;
	next_index = node->cached_next_index;
	u32 frag_sent = 0, small_packets = 0;
	u32 *buffer = 0;

	while (n_left_from > 0)
	{
	vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	u32 pi0, *frag_from, frag_left;
	vlib_buffer_t *p0;
	ip_frag_error_t error0;
	int next0;

	/*
	* Note: The packet is not enqueued now. It is instead put
	* in a vector where other fragments will be put as well.
	*/
	pi0 = from[0];
	from += 1;
	n_left_from -= 1;
	error0 = IP_FRAG_ERROR_NONE;

	p0 = vlib_get_buffer (vm, pi0);
	if (is_ip6)
	ip6_frag_do_fragment (vm, pi0, &buffer, &error0);
	else
	ip4_frag_do_fragment (vm, pi0, &buffer, &error0);

	if (PREDICT_FALSE (p0->flags & VLIB_BUFFER_IS_TRACED))
	{
	ip_frag_trace_t *tr =
	vlib_add_trace (vm, node, p0, sizeof (*tr));
	tr->mtu = vnet_buffer (p0)->ip_frag.mtu;
	tr->ipv6 = is_ip6 ? 1 : 0;
	tr->n_fragments = vec_len (buffer);
	tr->next = vnet_buffer (p0)->ip_frag.next_index;
	}

	if (!is_ip6 && error0 == IP_FRAG_ERROR_DONT_FRAGMENT_SET)
	{
	icmp4_error_set_vnet_buffer (p0, ICMP4_destination_unreachable,
	ICMP4_destination_unreachable_fragmentation_needed_and_dont_fragment_set,
	vnet_buffer (p0)->ip_frag.mtu);
	next0 = IP4_FRAG_NEXT_ICMP_ERROR;
	}
	else
	{
	if (is_ip6)
	next0 =
	(error0 ==
	IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
	ip_frag.next_index : IP6_FRAG_NEXT_DROP;
	else
	next0 =
	(error0 ==
	IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
	ip_frag.next_index : IP4_FRAG_NEXT_DROP;
	}

	if (error0 == IP_FRAG_ERROR_NONE)
	{
	/* Free original buffer chain */
	frag_sent += vec_len (buffer);
	small_packets += (vec_len (buffer) == 1);
	vlib_buffer_free_one (vm, pi0); /* Free original packet */
	}
	else
	{
	vlib_error_count (vm, node_index, error0, 1);
	vec_add1 (buffer, pi0); /* Get rid of the original buffer */
	}

	/* Send fragments that were added in the frame */
	frag_from = buffer;
	frag_left = vec_len (buffer);

	while (frag_left > 0)
	{
	while (frag_left > 0 && n_left_to_next > 0)
	{
	u32 i;
	i = to_next[0] = frag_from[0];
	frag_from += 1;
	frag_left -= 1;
	to_next += 1;
	n_left_to_next -= 1;

	vlib_get_buffer (vm, i)->error = error_node->errors[error0];
	vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
	to_next, n_left_to_next, i,
	next0);
	}
	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	vlib_get_next_frame (vm, node, next_index, to_next,
	n_left_to_next);
	}
	vec_reset_length (buffer);
	}
	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	}
	vec_free (buffer);

	vlib_node_increment_counter (vm, node_index,
	IP_FRAG_ERROR_FRAGMENT_SENT, frag_sent);
	vlib_node_increment_counter (vm, node_index,
	IP_FRAG_ERROR_SMALL_PACKET, small_packets);

	return frame->n_vectors;
	}



	static uword
	ip4_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	return frag_node_inline (vm, node, frame, ip4_frag_node.index,
	0 /* is_ip6 */ );
	}

	static uword
	ip6_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	return frag_node_inline (vm, node, frame, ip6_frag_node.index,
	1 /* is_ip6 */ );
	}

	/*
	* Fragments the packet given in from_bi. Fragments are returned in the buffer vector.
	* Caller must ensure the original packet is freed.
	*/
	void
	ip6_frag_do_fragment (vlib_main_t * vm, u32 from_bi, u32 ** buffer,
	ip_frag_error_t * error)
	{
	vlib_buffer_t *from_b;
	ip6_header_t *ip6;
	u16 mtu, len, max, rem, ip_frag_id;

	from_b = vlib_get_buffer (vm, from_bi);
	mtu = vnet_buffer (from_b)->ip_frag.mtu;
	ip6 = (ip6_header_t *) vlib_buffer_get_current (from_b);

	rem = clib_net_to_host_u16 (ip6->payload_length);
	max = (mtu - sizeof (ip6_header_t) - sizeof (ip6_frag_hdr_t)) & ~0x7; // TODO: Is max correct??

	if (rem >
	(vlib_buffer_length_in_chain (vm, from_b) - sizeof (ip6_header_t)))
	{
	*error = IP_FRAG_ERROR_MALFORMED;
	return;
	}

	/* TODO: Look through header chain for fragmentation header */
	if (ip6->protocol == IP_PROTOCOL_IPV6_FRAGMENTATION)
	{
	*error = IP_FRAG_ERROR_MALFORMED;
	return;
	}

	u8 from_data = (void ) (ip6 + 1);
	vlib_buffer_t *org_from_b = from_b;
	u16 fo = 0;
	u16 left_in_from_buffer = from_b->current_length - sizeof (ip6_header_t);
	u16 ptr = 0;

	ip_frag_id = ++running_fragment_id; // Fix

	/* Do the actual fragmentation */
	while (rem)
	{
	u32 to_bi;
	vlib_buffer_t *to_b;
	ip6_header_t *to_ip6;
	ip6_frag_hdr_t *to_frag_hdr;
	u8 *to_data;

	len =
	(rem >
	(mtu - sizeof (ip6_header_t) - sizeof (ip6_frag_hdr_t)) ? max : rem);
	if (len != rem) /* Last fragment does not need to divisible by 8 */
	len &= ~0x7;
	if ((to_b = frag_buffer_alloc (org_from_b, &to_bi)) == 0)
	{
	*error = IP_FRAG_ERROR_MEMORY;
	return;
	}
	vec_add1 (*buffer, to_bi);
	frag_set_sw_if_index (to_b, org_from_b);

	/* Copy ip6 header */
	clib_memcpy_fast (to_b->data, ip6, sizeof (ip6_header_t));
	to_ip6 = vlib_buffer_get_current (to_b);
	to_frag_hdr = (ip6_frag_hdr_t *) (to_ip6 + 1);
	to_data = (void *) (to_frag_hdr + 1);

	/* Spin through from buffers filling up the to buffer */
	u16 left_in_to_buffer = len, to_ptr = 0;
	while (1)
	{
	u16 bytes_to_copy;

	/* Figure out how many bytes we can safely copy */
	bytes_to_copy = left_in_to_buffer <= left_in_from_buffer ?
	left_in_to_buffer : left_in_from_buffer;
	clib_memcpy_fast (to_data + to_ptr, from_data + ptr, bytes_to_copy);
	left_in_to_buffer -= bytes_to_copy;
	ptr += bytes_to_copy;
	left_in_from_buffer -= bytes_to_copy;
	if (left_in_to_buffer == 0)
	break;

	ASSERT (left_in_from_buffer <= 0);
	/* Move buffer */
	if (!(from_b->flags & VLIB_BUFFER_NEXT_PRESENT))
	{
	*error = IP_FRAG_ERROR_MALFORMED;
	return;
	}
	from_b = vlib_get_buffer (vm, from_b->next_buffer);
	from_data = (u8 *) vlib_buffer_get_current (from_b);
	ptr = 0;
	left_in_from_buffer = from_b->current_length;
	to_ptr += bytes_to_copy;
	}

	to_b->current_length =
	len + sizeof (ip6_header_t) + sizeof (ip6_frag_hdr_t);
	to_ip6->payload_length =
	clib_host_to_net_u16 (len + sizeof (ip6_frag_hdr_t));
	to_ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
	to_frag_hdr->fragment_offset_and_more =
	ip6_frag_hdr_offset_and_more ((fo >> 3), len != rem);
	to_frag_hdr->identification = ip_frag_id;
	to_frag_hdr->next_hdr = ip6->protocol;
	to_frag_hdr->rsv = 0;

	rem -= len;
	fo += len;
	}
	}

	static char *ip4_frag_error_strings[] = {
	#define _(sym,string) string,
	foreach_ip_frag_error
	#undef _
	};

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (ip4_frag_node) = {
	.function = ip4_frag,
	.name = IP4_FRAG_NODE_NAME,
	.vector_size = sizeof (u32),
	.format_trace = format_ip_frag_trace,
	.type = VLIB_NODE_TYPE_INTERNAL,

	.n_errors = IP_FRAG_N_ERROR,
	.error_strings = ip4_frag_error_strings,

	.n_next_nodes = IP4_FRAG_N_NEXT,
	.next_nodes = {
	[IP4_FRAG_NEXT_IP4_REWRITE] = "ip4-rewrite",
	[IP4_FRAG_NEXT_IP4_LOOKUP] = "ip4-lookup",
	[IP4_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
	[IP4_FRAG_NEXT_ICMP_ERROR] = "ip4-icmp-error",
	[IP4_FRAG_NEXT_DROP] = "ip4-drop"
	},
	};
	/* INDENT-ON */

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (ip6_frag_node) = {
	.function = ip6_frag,
	.name = IP6_FRAG_NODE_NAME,
	.vector_size = sizeof (u32),
	.format_trace = format_ip_frag_trace,
	.type = VLIB_NODE_TYPE_INTERNAL,

	.n_errors = IP_FRAG_N_ERROR,
	.error_strings = ip4_frag_error_strings,

	.n_next_nodes = IP6_FRAG_N_NEXT,
	.next_nodes = {
	[IP6_FRAG_NEXT_IP6_REWRITE] = "ip6-rewrite",
	[IP6_FRAG_NEXT_IP4_LOOKUP] = "ip4-lookup",
	[IP6_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
	[IP6_FRAG_NEXT_DROP] = "ip6-drop"
	},
	};
	/* INDENT-ON */

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/