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 header_offset;
   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 offset: %u mtu: %u fragments: %u",
 	      t->ipv6 ? "6" : "4", t->header_offset, t->mtu, t->n_fragments);
   return s;
 }

 static u32 running_fragment_id;

 static void
 ip4_frag_do_fragment (vlib_main_t * vm, u32 pi, u32 ** buffer,
 		      ip_frag_error_t * error)
 {
   vlib_buffer_t *p;
   ip4_header_t *ip4;
   u16 mtu, ptr, len, max, rem, offset, ip_frag_id, ip_frag_offset;
   u8 *packet, more;

   vec_add1 (*buffer, pi);
   p = vlib_get_buffer (vm, pi);
   offset = vnet_buffer (p)->ip_frag.header_offset;
   mtu = vnet_buffer (p)->ip_frag.mtu;
   packet = (u8 *) vlib_buffer_get_current (p);
   ip4 = (ip4_header_t *) (packet + offset);

   rem = clib_net_to_host_u16 (ip4->length) - sizeof (*ip4);
   ptr = 0;
   max = (mtu - sizeof (*ip4) - vnet_buffer (p)->ip_frag.header_offset) & ~0x7;

   if (rem < (p->current_length - offset - sizeof (*ip4)))
     {
       *error = IP_FRAG_ERROR_MALFORMED;
       return;
     }

   if (mtu < sizeof (*ip4))
     {
       *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;
     }

   //Do the actual fragmentation
   while (rem)
     {
       u32 bi;
       vlib_buffer_t *b;
       ip4_header_t *fip4;

       len =
 	(rem >
 	 (mtu - sizeof (*ip4) -
 	  vnet_buffer (p)->ip_frag.header_offset)) ? max : rem;

       if (ptr == 0)
 	{
 	  bi = pi;
 	  b = p;
 	  fip4 = (ip4_header_t *) (vlib_buffer_get_current (b) + offset);
 	}
       else
 	{
 	  if (!vlib_buffer_alloc (vm, &bi, 1))
 	    {
 	      *error = IP_FRAG_ERROR_MEMORY;
 	      return;
 	    }
 	  vec_add1 (*buffer, bi);
 	  b = vlib_get_buffer (vm, bi);
 	  vnet_buffer (b)->sw_if_index[VLIB_RX] =
 	    vnet_buffer (p)->sw_if_index[VLIB_RX];
 	  vnet_buffer (b)->sw_if_index[VLIB_TX] =
 	    vnet_buffer (p)->sw_if_index[VLIB_TX];
 	  fip4 = (ip4_header_t *) (vlib_buffer_get_current (b) + offset);

 	  //Copy offset and ip4 header
 	  clib_memcpy (b->data, packet, offset + sizeof (*ip4));
 	  //Copy data
 	  clib_memcpy (((u8 *) (fip4)) + sizeof (*fip4),
 		       packet + offset + sizeof (*fip4) + ptr, len);
 	}
       b->current_length = offset + len + sizeof (*fip4);

       fip4->fragment_id = ip_frag_id;
       fip4->flags_and_fragment_offset =
 	clib_host_to_net_u16 ((ptr >> 3) + ip_frag_offset);
       fip4->flags_and_fragment_offset |=
 	clib_host_to_net_u16 (((len != rem) || more) << 13);
       // ((len0 != rem0) || more0) << 13 is optimization for
       // ((len0 != rem0) || more0) ? IP4_HEADER_FLAG_MORE_FRAGMENTS : 0
       fip4->length = clib_host_to_net_u16 (len + sizeof (*fip4));
       fip4->checksum = ip4_header_checksum (fip4);

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

       rem -= len;
       ptr += len;
     }
 }

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

 static uword
 ip4_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   u32 n_left_from, *from, next_index, *to_next, n_left_to_next;
   vlib_node_runtime_t *error_node =
     vlib_node_get_runtime (vm, ip4_frag_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;
 	  ip4_frag_next_t 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);
 	  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->header_offset = vnet_buffer (p0)->ip_frag.header_offset;
 	      tr->mtu = vnet_buffer (p0)->ip_frag.mtu;
 	      tr->ipv6 = 0;
 	      tr->n_fragments = vec_len (buffer);
 	      tr->next = vnet_buffer (p0)->ip_frag.next_index;
 	    }

 	  if (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);
 	      vlib_buffer_advance (p0,
 				   vnet_buffer (p0)->ip_frag.header_offset);
 	      next0 = IP4_FRAG_NEXT_ICMP_ERROR;
 	    }
 	  else
 	    next0 =
 	      (error0 ==
 	       IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
 	      ip_frag.next_index : IP4_FRAG_NEXT_DROP;

 	  if (error0 == IP_FRAG_ERROR_NONE)
 	    {
 	      frag_sent += vec_len (buffer);
 	      small_packets += (vec_len (buffer) == 1);
 	    }
 	  else
 	    vlib_error_count (vm, ip4_frag_node.index, error0, 1);

 	  //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, ip4_frag_node.index,
 			       IP_FRAG_ERROR_FRAGMENT_SENT, frag_sent);
   vlib_node_increment_counter (vm, ip4_frag_node.index,
 			       IP_FRAG_ERROR_SMALL_PACKET, small_packets);

   return frame->n_vectors;
 }


 static void
 ip6_frag_do_fragment (vlib_main_t * vm, u32 pi, u32 ** buffer,
 		      ip_frag_error_t * error)
 {
   vlib_buffer_t *p;
   ip6_header_t *ip6_hdr;
   ip6_frag_hdr_t *frag_hdr;
   u8 *payload, *next_header;

   p = vlib_get_buffer (vm, pi);

   //Parsing the IPv6 headers
   ip6_hdr =
     vlib_buffer_get_current (p) + vnet_buffer (p)->ip_frag.header_offset;
   payload = (u8 *) (ip6_hdr + 1);
   next_header = &ip6_hdr->protocol;
   if (*next_header == IP_PROTOCOL_IP6_HOP_BY_HOP_OPTIONS)
     {
       next_header = payload;
       payload += payload[1] * 8;
     }

   if (*next_header == IP_PROTOCOL_IP6_DESTINATION_OPTIONS)
     {
       next_header = payload;
       payload += payload[1] * 8;
     }

   if (*next_header == IP_PROTOCOL_IPV6_ROUTE)
     {
       next_header = payload;
       payload += payload[1] * 8;
     }

   if (PREDICT_FALSE
       (payload >= (u8 *) vlib_buffer_get_current (p) + p->current_length))
     {
       //A malicious packet could set an extension header with a too big size
       //and make us modify another vlib_buffer
       *error = IP_FRAG_ERROR_MALFORMED;
       return;
     }

   u8 has_more;
   u16 initial_offset;
   if (*next_header == IP_PROTOCOL_IPV6_FRAGMENTATION)
     {
       //The fragmentation header is already there
       frag_hdr = (ip6_frag_hdr_t *) payload;
       has_more = ip6_frag_hdr_more (frag_hdr);
       initial_offset = ip6_frag_hdr_offset (frag_hdr);
     }
   else
     {
       //Insert a fragmentation header in the packet
       u8 nh = *next_header;
       *next_header = IP_PROTOCOL_IPV6_FRAGMENTATION;
       vlib_buffer_advance (p, -sizeof (*frag_hdr));
       u8 *start = vlib_buffer_get_current (p);
       memmove (start, start + sizeof (*frag_hdr),
 	       payload - (start + sizeof (*frag_hdr)));
       frag_hdr = (ip6_frag_hdr_t *) (payload - sizeof (*frag_hdr));
       frag_hdr->identification = ++running_fragment_id;
       frag_hdr->next_hdr = nh;
       frag_hdr->rsv = 0;
       has_more = 0;
       initial_offset = 0;
     }
   payload = (u8 *) (frag_hdr + 1);

   u16 headers_len = payload - (u8 *) vlib_buffer_get_current (p);
   u16 max_payload = vnet_buffer (p)->ip_frag.mtu - headers_len;
   u16 rem = p->current_length - headers_len;
   u16 ptr = 0;

   if (max_payload < 8)
     {
       *error = IP_FRAG_ERROR_CANT_FRAGMENT_HEADER;
       return;
     }

   while (rem)
     {
       u32 bi;
       vlib_buffer_t *b;
       u16 len = (rem > max_payload) ? (max_payload & ~0x7) : rem;
       rem -= len;

       if (ptr != 0)
 	{
 	  if (!vlib_buffer_alloc (vm, &bi, 1))
 	    {
 	      *error = IP_FRAG_ERROR_MEMORY;
 	      return;
 	    }
 	  b = vlib_get_buffer (vm, bi);
 	  vnet_buffer (b)->sw_if_index[VLIB_RX] =
 	    vnet_buffer (p)->sw_if_index[VLIB_RX];
 	  vnet_buffer (b)->sw_if_index[VLIB_TX] =
 	    vnet_buffer (p)->sw_if_index[VLIB_TX];
 	  clib_memcpy (vlib_buffer_get_current (b),
 		       vlib_buffer_get_current (p), headers_len);
 	  clib_memcpy (vlib_buffer_get_current (b) + headers_len,
 		       payload + ptr, len);
 	  frag_hdr =
 	    vlib_buffer_get_current (b) + headers_len - sizeof (*frag_hdr);
 	}
       else
 	{
 	  bi = pi;
 	  b = vlib_get_buffer (vm, bi);
 	  //frag_hdr already set here
 	}

       ip6_hdr =
 	vlib_buffer_get_current (b) + vnet_buffer (p)->ip_frag.header_offset;
       frag_hdr->fragment_offset_and_more =
 	ip6_frag_hdr_offset_and_more (initial_offset + (ptr >> 3),
 				      (rem || has_more));
       b->current_length = headers_len + len;
       ip6_hdr->payload_length =
 	clib_host_to_net_u16 (b->current_length -
 			      vnet_buffer (p)->ip_frag.header_offset -
 			      sizeof (*ip6_hdr));

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

       vec_add1 (*buffer, bi);

       ptr += len;
     }
 }

 static uword
 ip6_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   u32 n_left_from, *from, next_index, *to_next, n_left_to_next;
   vlib_node_runtime_t *error_node =
     vlib_node_get_runtime (vm, ip6_frag_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;
 	  ip6_frag_next_t next0;

 	  pi0 = from[0];
 	  from += 1;
 	  n_left_from -= 1;
 	  error0 = IP_FRAG_ERROR_NONE;

 	  p0 = vlib_get_buffer (vm, pi0);
 	  ip6_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->header_offset = vnet_buffer (p0)->ip_frag.header_offset;
 	      tr->mtu = vnet_buffer (p0)->ip_frag.mtu;
 	      tr->ipv6 = 1;
 	      tr->n_fragments = vec_len (buffer);
 	      tr->next = vnet_buffer (p0)->ip_frag.next_index;
 	    }

 	  next0 =
 	    (error0 ==
 	     IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
 	    ip_frag.next_index : IP6_FRAG_NEXT_DROP;
 	  frag_sent += vec_len (buffer);
 	  small_packets += (vec_len (buffer) == 1);

 	  //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, ip6_frag_node.index,
 			       IP_FRAG_ERROR_FRAGMENT_SENT, frag_sent);
   vlib_node_increment_counter (vm, ip6_frag_node.index,
 			       IP_FRAG_ERROR_SMALL_PACKET, small_packets);

   return frame->n_vectors;
 }

 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_LOOKUP] = "ip4-lookup",
     [IP4_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
     [IP4_FRAG_NEXT_ICMP_ERROR] = "ip4-icmp-error",
     [IP4_FRAG_NEXT_DROP] = "error-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_IP4_LOOKUP] = "ip4-lookup",
     [IP6_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
     [IP6_FRAG_NEXT_DROP] = "error-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 header_offset;
	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 offset: %u mtu: %u fragments: %u",
	t->ipv6 ? "6" : "4", t->header_offset, t->mtu, t->n_fragments);
	return s;
	}

	static u32 running_fragment_id;

	static void
	ip4_frag_do_fragment (vlib_main_t * vm, u32 pi, u32 ** buffer,
	ip_frag_error_t * error)
	{
	vlib_buffer_t *p;
	ip4_header_t *ip4;
	u16 mtu, ptr, len, max, rem, offset, ip_frag_id, ip_frag_offset;
	u8 *packet, more;

	vec_add1 (*buffer, pi);
	p = vlib_get_buffer (vm, pi);
	offset = vnet_buffer (p)->ip_frag.header_offset;
	mtu = vnet_buffer (p)->ip_frag.mtu;
	packet = (u8 *) vlib_buffer_get_current (p);
	ip4 = (ip4_header_t *) (packet + offset);

	rem = clib_net_to_host_u16 (ip4->length) - sizeof (*ip4);
	ptr = 0;
	max = (mtu - sizeof (*ip4) - vnet_buffer (p)->ip_frag.header_offset) & ~0x7;

	if (rem < (p->current_length - offset - sizeof (*ip4)))
	{
	*error = IP_FRAG_ERROR_MALFORMED;
	return;
	}

	if (mtu < sizeof (*ip4))
	{
	*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;
	}

	//Do the actual fragmentation
	while (rem)
	{
	u32 bi;
	vlib_buffer_t *b;
	ip4_header_t *fip4;

	len =
	(rem >
	(mtu - sizeof (*ip4) -
	vnet_buffer (p)->ip_frag.header_offset)) ? max : rem;

	if (ptr == 0)
	{
	bi = pi;
	b = p;
	fip4 = (ip4_header_t *) (vlib_buffer_get_current (b) + offset);
	}
	else
	{
	if (!vlib_buffer_alloc (vm, &bi, 1))
	{
	*error = IP_FRAG_ERROR_MEMORY;
	return;
	}
	vec_add1 (*buffer, bi);
	b = vlib_get_buffer (vm, bi);
	vnet_buffer (b)->sw_if_index[VLIB_RX] =
	vnet_buffer (p)->sw_if_index[VLIB_RX];
	vnet_buffer (b)->sw_if_index[VLIB_TX] =
	vnet_buffer (p)->sw_if_index[VLIB_TX];
	fip4 = (ip4_header_t *) (vlib_buffer_get_current (b) + offset);

	//Copy offset and ip4 header
	clib_memcpy (b->data, packet, offset + sizeof (*ip4));
	//Copy data
	clib_memcpy (((u8 ) (fip4)) + sizeof (fip4),
	packet + offset + sizeof (*fip4) + ptr, len);
	}
	b->current_length = offset + len + sizeof (*fip4);

	fip4->fragment_id = ip_frag_id;
	fip4->flags_and_fragment_offset =
	clib_host_to_net_u16 ((ptr >> 3) + ip_frag_offset);
	fip4->flags_and_fragment_offset \|=
	clib_host_to_net_u16 (((len != rem) \|\| more) << 13);
	// ((len0 != rem0) \|\| more0) << 13 is optimization for
	// ((len0 != rem0) \|\| more0) ? IP4_HEADER_FLAG_MORE_FRAGMENTS : 0
	fip4->length = clib_host_to_net_u16 (len + sizeof (*fip4));
	fip4->checksum = ip4_header_checksum (fip4);

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

	rem -= len;
	ptr += len;
	}
	}

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

	static uword
	ip4_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	u32 n_left_from, from, next_index, to_next, n_left_to_next;
	vlib_node_runtime_t *error_node =
	vlib_node_get_runtime (vm, ip4_frag_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;
	ip4_frag_next_t 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);
	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->header_offset = vnet_buffer (p0)->ip_frag.header_offset;
	tr->mtu = vnet_buffer (p0)->ip_frag.mtu;
	tr->ipv6 = 0;
	tr->n_fragments = vec_len (buffer);
	tr->next = vnet_buffer (p0)->ip_frag.next_index;
	}

	if (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);
	vlib_buffer_advance (p0,
	vnet_buffer (p0)->ip_frag.header_offset);
	next0 = IP4_FRAG_NEXT_ICMP_ERROR;
	}
	else
	next0 =
	(error0 ==
	IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
	ip_frag.next_index : IP4_FRAG_NEXT_DROP;

	if (error0 == IP_FRAG_ERROR_NONE)
	{
	frag_sent += vec_len (buffer);
	small_packets += (vec_len (buffer) == 1);
	}
	else
	vlib_error_count (vm, ip4_frag_node.index, error0, 1);

	//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, ip4_frag_node.index,
	IP_FRAG_ERROR_FRAGMENT_SENT, frag_sent);
	vlib_node_increment_counter (vm, ip4_frag_node.index,
	IP_FRAG_ERROR_SMALL_PACKET, small_packets);

	return frame->n_vectors;
	}


	static void
	ip6_frag_do_fragment (vlib_main_t * vm, u32 pi, u32 ** buffer,
	ip_frag_error_t * error)
	{
	vlib_buffer_t *p;
	ip6_header_t *ip6_hdr;
	ip6_frag_hdr_t *frag_hdr;
	u8 payload, next_header;

	p = vlib_get_buffer (vm, pi);

	//Parsing the IPv6 headers
	ip6_hdr =
	vlib_buffer_get_current (p) + vnet_buffer (p)->ip_frag.header_offset;
	payload = (u8 *) (ip6_hdr + 1);
	next_header = &ip6_hdr->protocol;
	if (*next_header == IP_PROTOCOL_IP6_HOP_BY_HOP_OPTIONS)
	{
	next_header = payload;
	payload += payload[1] * 8;
	}

	if (*next_header == IP_PROTOCOL_IP6_DESTINATION_OPTIONS)
	{
	next_header = payload;
	payload += payload[1] * 8;
	}

	if (*next_header == IP_PROTOCOL_IPV6_ROUTE)
	{
	next_header = payload;
	payload += payload[1] * 8;
	}

	if (PREDICT_FALSE
	(payload >= (u8 *) vlib_buffer_get_current (p) + p->current_length))
	{
	//A malicious packet could set an extension header with a too big size
	//and make us modify another vlib_buffer
	*error = IP_FRAG_ERROR_MALFORMED;
	return;
	}

	u8 has_more;
	u16 initial_offset;
	if (*next_header == IP_PROTOCOL_IPV6_FRAGMENTATION)
	{
	//The fragmentation header is already there
	frag_hdr = (ip6_frag_hdr_t *) payload;
	has_more = ip6_frag_hdr_more (frag_hdr);
	initial_offset = ip6_frag_hdr_offset (frag_hdr);
	}
	else
	{
	//Insert a fragmentation header in the packet
	u8 nh = *next_header;
	*next_header = IP_PROTOCOL_IPV6_FRAGMENTATION;
	vlib_buffer_advance (p, -sizeof (*frag_hdr));
	u8 *start = vlib_buffer_get_current (p);
	memmove (start, start + sizeof (*frag_hdr),
	payload - (start + sizeof (*frag_hdr)));
	frag_hdr = (ip6_frag_hdr_t ) (payload - sizeof (frag_hdr));
	frag_hdr->identification = ++running_fragment_id;
	frag_hdr->next_hdr = nh;
	frag_hdr->rsv = 0;
	has_more = 0;
	initial_offset = 0;
	}
	payload = (u8 *) (frag_hdr + 1);

	u16 headers_len = payload - (u8 *) vlib_buffer_get_current (p);
	u16 max_payload = vnet_buffer (p)->ip_frag.mtu - headers_len;
	u16 rem = p->current_length - headers_len;
	u16 ptr = 0;

	if (max_payload < 8)
	{
	*error = IP_FRAG_ERROR_CANT_FRAGMENT_HEADER;
	return;
	}

	while (rem)
	{
	u32 bi;
	vlib_buffer_t *b;
	u16 len = (rem > max_payload) ? (max_payload & ~0x7) : rem;
	rem -= len;

	if (ptr != 0)
	{
	if (!vlib_buffer_alloc (vm, &bi, 1))
	{
	*error = IP_FRAG_ERROR_MEMORY;
	return;
	}
	b = vlib_get_buffer (vm, bi);
	vnet_buffer (b)->sw_if_index[VLIB_RX] =
	vnet_buffer (p)->sw_if_index[VLIB_RX];
	vnet_buffer (b)->sw_if_index[VLIB_TX] =
	vnet_buffer (p)->sw_if_index[VLIB_TX];
	clib_memcpy (vlib_buffer_get_current (b),
	vlib_buffer_get_current (p), headers_len);
	clib_memcpy (vlib_buffer_get_current (b) + headers_len,
	payload + ptr, len);
	frag_hdr =
	vlib_buffer_get_current (b) + headers_len - sizeof (*frag_hdr);
	}
	else
	{
	bi = pi;
	b = vlib_get_buffer (vm, bi);
	//frag_hdr already set here
	}

	ip6_hdr =
	vlib_buffer_get_current (b) + vnet_buffer (p)->ip_frag.header_offset;
	frag_hdr->fragment_offset_and_more =
	ip6_frag_hdr_offset_and_more (initial_offset + (ptr >> 3),
	(rem \|\| has_more));
	b->current_length = headers_len + len;
	ip6_hdr->payload_length =
	clib_host_to_net_u16 (b->current_length -
	vnet_buffer (p)->ip_frag.header_offset -
	sizeof (*ip6_hdr));

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

	vec_add1 (*buffer, bi);

	ptr += len;
	}
	}

	static uword
	ip6_frag (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	u32 n_left_from, from, next_index, to_next, n_left_to_next;
	vlib_node_runtime_t *error_node =
	vlib_node_get_runtime (vm, ip6_frag_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;
	ip6_frag_next_t next0;

	pi0 = from[0];
	from += 1;
	n_left_from -= 1;
	error0 = IP_FRAG_ERROR_NONE;

	p0 = vlib_get_buffer (vm, pi0);
	ip6_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->header_offset = vnet_buffer (p0)->ip_frag.header_offset;
	tr->mtu = vnet_buffer (p0)->ip_frag.mtu;
	tr->ipv6 = 1;
	tr->n_fragments = vec_len (buffer);
	tr->next = vnet_buffer (p0)->ip_frag.next_index;
	}

	next0 =
	(error0 ==
	IP_FRAG_ERROR_NONE) ? vnet_buffer (p0)->
	ip_frag.next_index : IP6_FRAG_NEXT_DROP;
	frag_sent += vec_len (buffer);
	small_packets += (vec_len (buffer) == 1);

	//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, ip6_frag_node.index,
	IP_FRAG_ERROR_FRAGMENT_SENT, frag_sent);
	vlib_node_increment_counter (vm, ip6_frag_node.index,
	IP_FRAG_ERROR_SMALL_PACKET, small_packets);

	return frame->n_vectors;
	}

	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_LOOKUP] = "ip4-lookup",
	[IP4_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
	[IP4_FRAG_NEXT_ICMP_ERROR] = "ip4-icmp-error",
	[IP4_FRAG_NEXT_DROP] = "error-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_IP4_LOOKUP] = "ip4-lookup",
	[IP6_FRAG_NEXT_IP6_LOOKUP] = "ip6-lookup",
	[IP6_FRAG_NEXT_DROP] = "error-drop"
	},
	};
	/* INDENT-ON */

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