src/vnet/ip/ip4_pg.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2015 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_pg: IP v4 packet-generator interface
  *
  * 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.
  */

 #include <vnet/ip/ip.h>
 #include <vnet/pg/pg.h>

 #define IP4_PG_EDIT_CHECKSUM (1 << 0)
 #define IP4_PG_EDIT_LENGTH (1 << 1)

 static_always_inline void
 compute_length_and_or_checksum (vlib_main_t * vm,
 				u32 * packets,
 				u32 n_packets,
 				u32 ip_header_offset, u32 flags)
 {
   ASSERT (flags != 0);

   while (n_packets >= 2)
     {
       u32 pi0, pi1;
       vlib_buffer_t *p0, *p1;
       ip4_header_t *ip0, *ip1;
       ip_csum_t sum0, sum1;

       pi0 = packets[0];
       pi1 = packets[1];
       p0 = vlib_get_buffer (vm, pi0);
       p1 = vlib_get_buffer (vm, pi1);
       n_packets -= 2;
       packets += 2;

       ip0 = (void *) (p0->data + ip_header_offset);
       ip1 = (void *) (p1->data + ip_header_offset);

       if (flags & IP4_PG_EDIT_LENGTH)
 	{
 	  ip0->length =
 	    clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, p0) -
 				  ip_header_offset);
 	  ip1->length =
 	    clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, p1) -
 				  ip_header_offset);
 	}

       if (flags & IP4_PG_EDIT_CHECKSUM)
 	{
 	  ASSERT (ip4_header_bytes (ip0) == sizeof (ip0[0]));
 	  ASSERT (ip4_header_bytes (ip1) == sizeof (ip1[0]));

 	  ip0->checksum = 0;
 	  ip1->checksum = 0;

 	  ip4_partial_header_checksum_x2 (ip0, ip1, sum0, sum1);
 	  ip0->checksum = ~ip_csum_fold (sum0);
 	  ip1->checksum = ~ip_csum_fold (sum1);

 	  ASSERT (ip0->checksum == ip4_header_checksum (ip0));
 	  ASSERT (ip1->checksum == ip4_header_checksum (ip1));
 	}
     }

   while (n_packets >= 1)
     {
       u32 pi0;
       vlib_buffer_t *p0;
       ip4_header_t *ip0;
       ip_csum_t sum0;

       pi0 = packets[0];
       p0 = vlib_get_buffer (vm, pi0);
       n_packets -= 1;
       packets += 1;

       ip0 = (void *) (p0->data + ip_header_offset);

       if (flags & IP4_PG_EDIT_LENGTH)
 	ip0->length =
 	  clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, p0) -
 				ip_header_offset);

       if (flags & IP4_PG_EDIT_CHECKSUM)
 	{
 	  ASSERT (ip4_header_bytes (ip0) == sizeof (ip0[0]));

 	  ip0->checksum = 0;

 	  ip4_partial_header_checksum_x1 (ip0, sum0);
 	  ip0->checksum = ~ip_csum_fold (sum0);

 	  ASSERT (ip0->checksum == ip4_header_checksum (ip0));
 	}
     }
 }

 static void
 ip4_pg_edit_function (pg_main_t * pg,
 		      pg_stream_t * s,
 		      pg_edit_group_t * g, u32 * packets, u32 n_packets)
 {
   vlib_main_t *vm = vlib_get_main ();
   u32 ip_offset;

   ip_offset = g->start_byte_offset;

   switch (g->edit_function_opaque)
     {
     case IP4_PG_EDIT_LENGTH:
       compute_length_and_or_checksum (vm, packets, n_packets, ip_offset,
 				      IP4_PG_EDIT_LENGTH);
       break;

     case IP4_PG_EDIT_CHECKSUM:
       compute_length_and_or_checksum (vm, packets, n_packets, ip_offset,
 				      IP4_PG_EDIT_CHECKSUM);
       break;

     case IP4_PG_EDIT_LENGTH | IP4_PG_EDIT_CHECKSUM:
       compute_length_and_or_checksum (vm, packets, n_packets, ip_offset,
 				      IP4_PG_EDIT_LENGTH
 				      | IP4_PG_EDIT_CHECKSUM);
       break;

     default:
       ASSERT (0);
       break;
     }
 }

 typedef struct
 {
   pg_edit_t ip_version, header_length;
   pg_edit_t tos;
   pg_edit_t length;

   pg_edit_t fragment_id, fragment_offset;

   /* Flags together with fragment offset. */
   pg_edit_t mf_flag, df_flag, ce_flag;

   pg_edit_t ttl;

   pg_edit_t protocol;

   pg_edit_t checksum;

   pg_edit_t src_address, dst_address;
 } pg_ip4_header_t;

 static inline void
 pg_ip4_header_init (pg_ip4_header_t * p)
 {
   /* Initialize fields that are not bit fields in the IP header. */
 #define _(f) pg_edit_init (&p->f, ip4_header_t, f);
   _(tos);
   _(length);
   _(fragment_id);
   _(ttl);
   _(protocol);
   _(checksum);
   _(src_address);
   _(dst_address);
 #undef _

   /* Initialize bit fields. */
   pg_edit_init_bitfield (&p->header_length, ip4_header_t,
 			 ip_version_and_header_length, 0, 4);
   pg_edit_init_bitfield (&p->ip_version, ip4_header_t,
 			 ip_version_and_header_length, 4, 4);

   pg_edit_init_bitfield (&p->fragment_offset, ip4_header_t,
 			 flags_and_fragment_offset, 0, 13);
   pg_edit_init_bitfield (&p->mf_flag, ip4_header_t,
 			 flags_and_fragment_offset, 13, 1);
   pg_edit_init_bitfield (&p->df_flag, ip4_header_t,
 			 flags_and_fragment_offset, 14, 1);
   pg_edit_init_bitfield (&p->ce_flag, ip4_header_t,
 			 flags_and_fragment_offset, 15, 1);
 }

 uword
 unformat_pg_ip4_header (unformat_input_t * input, va_list * args)
 {
   pg_stream_t *s = va_arg (*args, pg_stream_t *);
   pg_ip4_header_t *p;
   u32 group_index;

   p = pg_create_edit_group (s, sizeof (p[0]), sizeof (ip4_header_t),
 			    &group_index);
   pg_ip4_header_init (p);

   /* Defaults. */
   pg_edit_set_fixed (&p->ip_version, 4);
   pg_edit_set_fixed (&p->header_length, sizeof (ip4_header_t) / sizeof (u32));

   pg_edit_set_fixed (&p->tos, 0);
   pg_edit_set_fixed (&p->ttl, 64);

   pg_edit_set_fixed (&p->fragment_id, 0);
   pg_edit_set_fixed (&p->fragment_offset, 0);
   pg_edit_set_fixed (&p->mf_flag, 0);
   pg_edit_set_fixed (&p->df_flag, 0);
   pg_edit_set_fixed (&p->ce_flag, 0);

   p->length.type = PG_EDIT_UNSPECIFIED;
   p->checksum.type = PG_EDIT_UNSPECIFIED;

   if (unformat (input, "%U: %U -> %U",
 		unformat_pg_edit,
 		unformat_ip_protocol, &p->protocol,
 		unformat_pg_edit,
 		unformat_ip4_address, &p->src_address,
 		unformat_pg_edit, unformat_ip4_address, &p->dst_address))
     goto found;

   if (!unformat (input, "%U:",
 		 unformat_pg_edit, unformat_ip_protocol, &p->protocol))
     goto error;

 found:
   /* Parse options. */
   while (1)
     {
       if (unformat (input, "version %U",
 		    unformat_pg_edit, unformat_pg_number, &p->ip_version))
 	;

       else if (unformat (input, "header-length %U",
 			 unformat_pg_edit,
 			 unformat_pg_number, &p->header_length))
 	;

       else if (unformat (input, "tos %U",
 			 unformat_pg_edit, unformat_pg_number, &p->tos))
 	;

       else if (unformat (input, "length %U",
 			 unformat_pg_edit, unformat_pg_number, &p->length))
 	;

       else if (unformat (input, "checksum %U",
 			 unformat_pg_edit, unformat_pg_number, &p->checksum))
 	;

       else if (unformat (input, "ttl %U",
 			 unformat_pg_edit, unformat_pg_number, &p->ttl))
 	;

       else if (unformat (input, "fragment id %U offset %U",
 			 unformat_pg_edit,
 			 unformat_pg_number, &p->fragment_id,
 			 unformat_pg_edit,
 			 unformat_pg_number, &p->fragment_offset))
 	{
 	  int i;
 	  for (i = 0; i < ARRAY_LEN (p->fragment_offset.values); i++)
 	    pg_edit_set_value (&p->fragment_offset, i,
 			       pg_edit_get_value (&p->fragment_offset,
 						  i) / 8);

 	}

       /* Flags. */
       else if (unformat (input, "mf") || unformat (input, "MF"))
 	pg_edit_set_fixed (&p->mf_flag, 1);

       else if (unformat (input, "df") || unformat (input, "DF"))
 	pg_edit_set_fixed (&p->df_flag, 1);

       else if (unformat (input, "ce") || unformat (input, "CE"))
 	pg_edit_set_fixed (&p->ce_flag, 1);

       /* Can't parse input: try next protocol level. */
       else
 	break;
     }

   {
     ip_main_t *im = &ip_main;
     ip_protocol_t protocol;
     ip_protocol_info_t *pi;

     pi = 0;
     if (p->protocol.type == PG_EDIT_FIXED)
       {
 	protocol = pg_edit_get_value (&p->protocol, PG_EDIT_LO);
 	pi = ip_get_protocol_info (im, protocol);
       }

     if (pi && pi->unformat_pg_edit
 	&& unformat_user (input, pi->unformat_pg_edit, s))
       ;

     else if (!unformat_user (input, unformat_pg_payload, s))
       goto error;

     if (p->length.type == PG_EDIT_UNSPECIFIED
 	&& s->min_packet_bytes == s->max_packet_bytes
 	&& group_index + 1 < vec_len (s->edit_groups))
       {
 	pg_edit_set_fixed (&p->length,
 			   pg_edit_group_n_bytes (s, group_index));
       }

     /* Compute IP header checksum if all edits are fixed. */
     if (p->checksum.type == PG_EDIT_UNSPECIFIED)
       {
 	ip4_header_t fixed_header, fixed_mask, cmp_mask;

 	/* See if header is all fixed and specified except for
 	   checksum field. */
 	clib_memset (&cmp_mask, ~0, sizeof (cmp_mask));
 	cmp_mask.checksum = 0;

 	pg_edit_group_get_fixed_packet_data (s, group_index,
 					     &fixed_header, &fixed_mask);
 	if (!memcmp (&fixed_mask, &cmp_mask, sizeof (cmp_mask)))
 	  pg_edit_set_fixed (&p->checksum,
 			     clib_net_to_host_u16 (ip4_header_checksum
 						   (&fixed_header)));
       }

     p = pg_get_edit_group (s, group_index);
     if (p->length.type == PG_EDIT_UNSPECIFIED
 	|| p->checksum.type == PG_EDIT_UNSPECIFIED)
       {
 	pg_edit_group_t *g = pg_stream_get_group (s, group_index);
 	g->edit_function = ip4_pg_edit_function;
 	g->edit_function_opaque = 0;
 	if (p->length.type == PG_EDIT_UNSPECIFIED)
 	  g->edit_function_opaque |= IP4_PG_EDIT_LENGTH;
 	if (p->checksum.type == PG_EDIT_UNSPECIFIED)
 	  g->edit_function_opaque |= IP4_PG_EDIT_CHECKSUM;
       }

     return 1;
   }

 error:
   /* Free up any edits we may have added. */
   pg_free_edit_group (s);
   return 0;
 }


 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2015 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_pg: IP v4 packet-generator interface
	*
	* 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.
	*/

	#include <vnet/ip/ip.h>
	#include <vnet/pg/pg.h>

	#define IP4_PG_EDIT_CHECKSUM (1 << 0)
	#define IP4_PG_EDIT_LENGTH (1 << 1)

	static_always_inline void
	compute_length_and_or_checksum (vlib_main_t * vm,
	u32 * packets,
	u32 n_packets,
	u32 ip_header_offset, u32 flags)
	{
	ASSERT (flags != 0);

	while (n_packets >= 2)
	{
	u32 pi0, pi1;
	vlib_buffer_t p0, p1;
	ip4_header_t ip0, ip1;
	ip_csum_t sum0, sum1;

	pi0 = packets[0];
	pi1 = packets[1];
	p0 = vlib_get_buffer (vm, pi0);
	p1 = vlib_get_buffer (vm, pi1);
	n_packets -= 2;
	packets += 2;

	ip0 = (void *) (p0->data + ip_header_offset);
	ip1 = (void *) (p1->data + ip_header_offset);

	if (flags & IP4_PG_EDIT_LENGTH)
	{
	ip0->length =
	clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, p0) -
	ip_header_offset);
	ip1->length =
	clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, p1) -
	ip_header_offset);
	}

	if (flags & IP4_PG_EDIT_CHECKSUM)
	{
	ASSERT (ip4_header_bytes (ip0) == sizeof (ip0[0]));
	ASSERT (ip4_header_bytes (ip1) == sizeof (ip1[0]));

	ip0->checksum = 0;
	ip1->checksum = 0;

	ip4_partial_header_checksum_x2 (ip0, ip1, sum0, sum1);
	ip0->checksum = ~ip_csum_fold (sum0);
	ip1->checksum = ~ip_csum_fold (sum1);

	ASSERT (ip0->checksum == ip4_header_checksum (ip0));
	ASSERT (ip1->checksum == ip4_header_checksum (ip1));
	}
	}

	while (n_packets >= 1)
	{
	u32 pi0;
	vlib_buffer_t *p0;
	ip4_header_t *ip0;
	ip_csum_t sum0;

	pi0 = packets[0];
	p0 = vlib_get_buffer (vm, pi0);
	n_packets -= 1;
	packets += 1;

	ip0 = (void *) (p0->data + ip_header_offset);

	if (flags & IP4_PG_EDIT_LENGTH)
	ip0->length =
	clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, p0) -
	ip_header_offset);

	if (flags & IP4_PG_EDIT_CHECKSUM)
	{
	ASSERT (ip4_header_bytes (ip0) == sizeof (ip0[0]));

	ip0->checksum = 0;

	ip4_partial_header_checksum_x1 (ip0, sum0);
	ip0->checksum = ~ip_csum_fold (sum0);

	ASSERT (ip0->checksum == ip4_header_checksum (ip0));
	}
	}
	}

	static void
	ip4_pg_edit_function (pg_main_t * pg,
	pg_stream_t * s,
	pg_edit_group_t * g, u32 * packets, u32 n_packets)
	{
	vlib_main_t *vm = vlib_get_main ();
	u32 ip_offset;

	ip_offset = g->start_byte_offset;

	switch (g->edit_function_opaque)
	{
	case IP4_PG_EDIT_LENGTH:
	compute_length_and_or_checksum (vm, packets, n_packets, ip_offset,
	IP4_PG_EDIT_LENGTH);
	break;

	case IP4_PG_EDIT_CHECKSUM:
	compute_length_and_or_checksum (vm, packets, n_packets, ip_offset,
	IP4_PG_EDIT_CHECKSUM);
	break;

	case IP4_PG_EDIT_LENGTH \| IP4_PG_EDIT_CHECKSUM:
	compute_length_and_or_checksum (vm, packets, n_packets, ip_offset,
	IP4_PG_EDIT_LENGTH
	\| IP4_PG_EDIT_CHECKSUM);
	break;

	default:
	ASSERT (0);
	break;
	}
	}

	typedef struct
	{
	pg_edit_t ip_version, header_length;
	pg_edit_t tos;
	pg_edit_t length;

	pg_edit_t fragment_id, fragment_offset;

	/* Flags together with fragment offset. */
	pg_edit_t mf_flag, df_flag, ce_flag;

	pg_edit_t ttl;

	pg_edit_t protocol;

	pg_edit_t checksum;

	pg_edit_t src_address, dst_address;
	} pg_ip4_header_t;

	static inline void
	pg_ip4_header_init (pg_ip4_header_t * p)
	{
	/* Initialize fields that are not bit fields in the IP header. */
	#define _(f) pg_edit_init (&p->f, ip4_header_t, f);
	_(tos);
	_(length);
	_(fragment_id);
	_(ttl);
	_(protocol);
	_(checksum);
	_(src_address);
	_(dst_address);
	#undef _

	/* Initialize bit fields. */
	pg_edit_init_bitfield (&p->header_length, ip4_header_t,
	ip_version_and_header_length, 0, 4);
	pg_edit_init_bitfield (&p->ip_version, ip4_header_t,
	ip_version_and_header_length, 4, 4);

	pg_edit_init_bitfield (&p->fragment_offset, ip4_header_t,
	flags_and_fragment_offset, 0, 13);
	pg_edit_init_bitfield (&p->mf_flag, ip4_header_t,
	flags_and_fragment_offset, 13, 1);
	pg_edit_init_bitfield (&p->df_flag, ip4_header_t,
	flags_and_fragment_offset, 14, 1);
	pg_edit_init_bitfield (&p->ce_flag, ip4_header_t,
	flags_and_fragment_offset, 15, 1);
	}

	uword
	unformat_pg_ip4_header (unformat_input_t * input, va_list * args)
	{
	pg_stream_t s = va_arg (args, pg_stream_t *);
	pg_ip4_header_t *p;
	u32 group_index;

	p = pg_create_edit_group (s, sizeof (p[0]), sizeof (ip4_header_t),
	&group_index);
	pg_ip4_header_init (p);

	/* Defaults. */
	pg_edit_set_fixed (&p->ip_version, 4);
	pg_edit_set_fixed (&p->header_length, sizeof (ip4_header_t) / sizeof (u32));

	pg_edit_set_fixed (&p->tos, 0);
	pg_edit_set_fixed (&p->ttl, 64);

	pg_edit_set_fixed (&p->fragment_id, 0);
	pg_edit_set_fixed (&p->fragment_offset, 0);
	pg_edit_set_fixed (&p->mf_flag, 0);
	pg_edit_set_fixed (&p->df_flag, 0);
	pg_edit_set_fixed (&p->ce_flag, 0);

	p->length.type = PG_EDIT_UNSPECIFIED;
	p->checksum.type = PG_EDIT_UNSPECIFIED;

	if (unformat (input, "%U: %U -> %U",
	unformat_pg_edit,
	unformat_ip_protocol, &p->protocol,
	unformat_pg_edit,
	unformat_ip4_address, &p->src_address,
	unformat_pg_edit, unformat_ip4_address, &p->dst_address))
	goto found;

	if (!unformat (input, "%U:",
	unformat_pg_edit, unformat_ip_protocol, &p->protocol))
	goto error;

	found:
	/* Parse options. */
	while (1)
	{
	if (unformat (input, "version %U",
	unformat_pg_edit, unformat_pg_number, &p->ip_version))
	;

	else if (unformat (input, "header-length %U",
	unformat_pg_edit,
	unformat_pg_number, &p->header_length))
	;

	else if (unformat (input, "tos %U",
	unformat_pg_edit, unformat_pg_number, &p->tos))
	;

	else if (unformat (input, "length %U",
	unformat_pg_edit, unformat_pg_number, &p->length))
	;

	else if (unformat (input, "checksum %U",
	unformat_pg_edit, unformat_pg_number, &p->checksum))
	;

	else if (unformat (input, "ttl %U",
	unformat_pg_edit, unformat_pg_number, &p->ttl))
	;

	else if (unformat (input, "fragment id %U offset %U",
	unformat_pg_edit,
	unformat_pg_number, &p->fragment_id,
	unformat_pg_edit,
	unformat_pg_number, &p->fragment_offset))
	{
	int i;
	for (i = 0; i < ARRAY_LEN (p->fragment_offset.values); i++)
	pg_edit_set_value (&p->fragment_offset, i,
	pg_edit_get_value (&p->fragment_offset,
	i) / 8);

	}

	/* Flags. */
	else if (unformat (input, "mf") \|\| unformat (input, "MF"))
	pg_edit_set_fixed (&p->mf_flag, 1);

	else if (unformat (input, "df") \|\| unformat (input, "DF"))
	pg_edit_set_fixed (&p->df_flag, 1);

	else if (unformat (input, "ce") \|\| unformat (input, "CE"))
	pg_edit_set_fixed (&p->ce_flag, 1);

	/* Can't parse input: try next protocol level. */
	else
	break;
	}

	{
	ip_main_t *im = &ip_main;
	ip_protocol_t protocol;
	ip_protocol_info_t *pi;

	pi = 0;
	if (p->protocol.type == PG_EDIT_FIXED)
	{
	protocol = pg_edit_get_value (&p->protocol, PG_EDIT_LO);
	pi = ip_get_protocol_info (im, protocol);
	}

	if (pi && pi->unformat_pg_edit
	&& unformat_user (input, pi->unformat_pg_edit, s))
	;

	else if (!unformat_user (input, unformat_pg_payload, s))
	goto error;

	if (p->length.type == PG_EDIT_UNSPECIFIED
	&& s->min_packet_bytes == s->max_packet_bytes
	&& group_index + 1 < vec_len (s->edit_groups))
	{
	pg_edit_set_fixed (&p->length,
	pg_edit_group_n_bytes (s, group_index));
	}

	/* Compute IP header checksum if all edits are fixed. */
	if (p->checksum.type == PG_EDIT_UNSPECIFIED)
	{
	ip4_header_t fixed_header, fixed_mask, cmp_mask;

	/* See if header is all fixed and specified except for
	checksum field. */
	clib_memset (&cmp_mask, ~0, sizeof (cmp_mask));
	cmp_mask.checksum = 0;

	pg_edit_group_get_fixed_packet_data (s, group_index,
	&fixed_header, &fixed_mask);
	if (!memcmp (&fixed_mask, &cmp_mask, sizeof (cmp_mask)))
	pg_edit_set_fixed (&p->checksum,
	clib_net_to_host_u16 (ip4_header_checksum
	(&fixed_header)));
	}

	p = pg_get_edit_group (s, group_index);
	if (p->length.type == PG_EDIT_UNSPECIFIED
	\|\| p->checksum.type == PG_EDIT_UNSPECIFIED)
	{
	pg_edit_group_t *g = pg_stream_get_group (s, group_index);
	g->edit_function = ip4_pg_edit_function;
	g->edit_function_opaque = 0;
	if (p->length.type == PG_EDIT_UNSPECIFIED)
	g->edit_function_opaque \|= IP4_PG_EDIT_LENGTH;
	if (p->checksum.type == PG_EDIT_UNSPECIFIED)
	g->edit_function_opaque \|= IP4_PG_EDIT_CHECKSUM;
	}

	return 1;
	}

	error:
	/* Free up any edits we may have added. */
	pg_free_edit_group (s);
	return 0;
	}


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