src/vnet/ip/ip4_packet.h - 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.
  */
 /*
  * ip4/packet.h: ip4 packet format
  *
  * 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_ip4_packet_h
 #define included_ip4_packet_h

 #include <vnet/ip/ip_packet.h>	/* for ip_csum_t */
 #include <vnet/tcp/tcp_packet.h>	/* for tcp_header_t */
 #include <vppinfra/byte_order.h>	/* for clib_net_to_host_u16 */

 /* IP4 address which can be accessed either as 4 bytes
    or as a 32-bit number. */
 typedef union
 {
   u8 data[4];
   u32 data_u32;
   /* Aliases. */
   u8 as_u8[4];
   u16 as_u16[2];
   u32 as_u32;
 } ip4_address_t;

 typedef struct
 {
   /* IP address must be first for ip_interface_address_get_address() to work */
   ip4_address_t ip4_addr;
   u32 fib_index;
 } ip4_address_fib_t;

 always_inline void
 ip4_addr_fib_init (ip4_address_fib_t * addr_fib,
 		   const ip4_address_t * address, u32 fib_index)
 {
   clib_memcpy_fast (&addr_fib->ip4_addr, address,
 		    sizeof (addr_fib->ip4_addr));
   addr_fib->fib_index = fib_index;
 }

 /* (src,dst) pair of addresses as found in packet header. */
 typedef struct
 {
   ip4_address_t src, dst;
 } ip4_address_pair_t;

 typedef struct
 {
   ip4_address_t addr, mask;
 } ip4_address_and_mask_t;

 typedef union
 {
   struct
   {
     /* 4 bit packet length (in 32bit units) and version VVVVLLLL.
        e.g. for packets w/ no options ip_version_and_header_length == 0x45. */
     u8 ip_version_and_header_length;

     /* Type of service. */
     ip_dscp_t tos;

     /* Total layer 3 packet length including this header. */
     u16 length;

     /* Fragmentation ID. */
     u16 fragment_id;

     /* 3 bits of flags and 13 bits of fragment offset (in units
        of 8 byte quantities). */
     u16 flags_and_fragment_offset;
 #define IP4_HEADER_FLAG_MORE_FRAGMENTS (1 << 13)
 #define IP4_HEADER_FLAG_DONT_FRAGMENT (1 << 14)
 #define IP4_HEADER_FLAG_CONGESTION (1 << 15)

     /* Time to live decremented by router at each hop. */
     u8 ttl;

     /* Next level protocol packet. */
     u8 protocol;

     /* Checksum. */
     u16 checksum;

     /* Source and destination address. */
     union
     {
       struct
       {
 	ip4_address_t src_address, dst_address;
       };
       ip4_address_pair_t address_pair;
     };
   };

   /* For checksumming we'll want to access IP header in word sized chunks. */
   /* For 64 bit machines. */
   /* *INDENT-OFF* */
   CLIB_PACKED (struct {
     u64 checksum_data_64[2];
     u32 checksum_data_64_32[1];
   });
   /* *INDENT-ON* */

   /* For 32 bit machines. */
   /* *INDENT-OFF* */
   CLIB_PACKED (struct {
     u32 checksum_data_32[5];
   });
   /* *INDENT-ON* */
 } ip4_header_t;

 /* Value of ip_version_and_header_length for packets w/o options. */
 #define IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS \
   ((4 << 4) | (sizeof (ip4_header_t) / sizeof (u32)))

 #define IP4_ROUTER_ALERT_OPTION 20

 always_inline u16
 ip4_get_fragment_offset (const ip4_header_t * i)
 {
   return clib_net_to_host_u16 (i->flags_and_fragment_offset) & 0x1fff;
 }

 always_inline u16
 ip4_get_fragment_more (const ip4_header_t * i)
 {
   return clib_net_to_host_u16 (i->flags_and_fragment_offset) &
     IP4_HEADER_FLAG_MORE_FRAGMENTS;
 }

 always_inline int
 ip4_is_fragment (const ip4_header_t * i)
 {
   return (i->flags_and_fragment_offset &
 	  clib_net_to_host_u16 (0x1fff | IP4_HEADER_FLAG_MORE_FRAGMENTS));
 }

 always_inline int
 ip4_is_first_fragment (const ip4_header_t * i)
 {
   return (i->flags_and_fragment_offset &
 	  clib_net_to_host_u16 (0x1fff | IP4_HEADER_FLAG_MORE_FRAGMENTS)) ==
     clib_net_to_host_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS);
 }

 /* Fragment offset in bytes. */
 always_inline int
 ip4_get_fragment_offset_bytes (const ip4_header_t * i)
 {
   return 8 * ip4_get_fragment_offset (i);
 }

 always_inline int
 ip4_header_bytes (const ip4_header_t * i)
 {
   return sizeof (u32) * (i->ip_version_and_header_length & 0xf);
 }

 always_inline void *
 ip4_next_header (ip4_header_t * i)
 {
   return (void *) i + ip4_header_bytes (i);
 }

 always_inline u16
 ip4_header_checksum (ip4_header_t * i)
 {
   int option_len = (i->ip_version_and_header_length & 0xf) - 5;
   uword sum = 0;
 #if uword_bits == 64
   u32 *iphdr = (u32 *) i;

   sum += iphdr[0];
   sum += iphdr[1];
   sum += *(u16 *) (iphdr + 2);
   /* skip checksum */
   sum += iphdr[3];
   sum += iphdr[4];

   if (PREDICT_FALSE (option_len > 0))
     switch (option_len)
       {
       case 10:
 	sum += iphdr[14];
       case 9:
 	sum += iphdr[13];
       case 8:
 	sum += iphdr[12];
       case 7:
 	sum += iphdr[11];
       case 6:
 	sum += iphdr[10];
       case 5:
 	sum += iphdr[9];
       case 4:
 	sum += iphdr[8];
       case 3:
 	sum += iphdr[7];
       case 2:
 	sum += iphdr[6];
       case 1:
 	sum += iphdr[5];
       default:
 	break;
       }

   sum = ((u32) sum) + (sum >> 32);
 #else
   u16 *iphdr = (u16 *) i;

   sum += iphdr[0];
   sum += iphdr[1];
   sum += iphdr[2];
   sum += iphdr[3];
   sum += iphdr[4];
   /* skip checksum */
   sum += iphdr[6];
   sum += iphdr[7];
   sum += iphdr[8];
   sum += iphdr[9];

   if (PREDICT_FALSE (option_len > 0))
     switch (option_len)
       {
       case 10:
 	sum += iphdr[28];
 	sum += iphdr[29];
       case 9:
 	sum += iphdr[26];
 	sum += iphdr[27];
       case 8:
 	sum += iphdr[24];
 	sum += iphdr[25];
       case 7:
 	sum += iphdr[22];
 	sum += iphdr[23];
       case 6:
 	sum += iphdr[20];
 	sum += iphdr[21];
       case 5:
 	sum += iphdr[18];
 	sum += iphdr[19];
       case 4:
 	sum += iphdr[16];
 	sum += iphdr[17];
       case 3:
 	sum += iphdr[14];
 	sum += iphdr[15];
       case 2:
 	sum += iphdr[12];
 	sum += iphdr[13];
       case 1:
 	sum += iphdr[10];
 	sum += iphdr[11];
       default:
 	break;
       }
 #endif

   sum = ((u16) sum) + (sum >> 16);
   sum = ((u16) sum) + (sum >> 16);
   return ~((u16) sum);
 }

 always_inline void
 ip4_header_set_dscp (ip4_header_t * ip4, ip_dscp_t dscp)
 {
   ip4->tos &= ~0xfc;
   /* not masking the dscp value to save th instruction
    * it shouldn't b necessary since the argument is an enum
    * whose range is therefore constrained in the CP. in the
    * DP it will have been taken from another packet, so again
    * constrained in  value */
   ip4->tos |= dscp << IP_PACKET_TC_FIELD_DSCP_BIT_SHIFT;
 }

 always_inline void
 ip4_header_set_ecn (ip4_header_t * ip4, ip_ecn_t ecn)
 {
   ip4->tos &= ~IP_PACKET_TC_FIELD_ECN_MASK;
   ip4->tos |= ecn;
 }

 always_inline void
 ip4_header_set_ecn_w_chksum (ip4_header_t * ip4, ip_ecn_t ecn)
 {
   ip_csum_t sum = ip4->checksum;
   u8 old = ip4->tos;
   u8 new = (old & ~IP_PACKET_TC_FIELD_ECN_MASK) | ecn;

   sum = ip_csum_update (sum, old, new, ip4_header_t, tos);
   ip4->checksum = ip_csum_fold (sum);
   ip4->tos = new;
 }

 always_inline ip_dscp_t
 ip4_header_get_dscp (const ip4_header_t * ip4)
 {
   return (ip4->tos >> IP_PACKET_TC_FIELD_DSCP_BIT_SHIFT);
 }

 always_inline ip_ecn_t
 ip4_header_get_ecn (const ip4_header_t * ip4)
 {
   return (ip4->tos & IP_PACKET_TC_FIELD_ECN_MASK);
 }

 always_inline void
 ip4_header_set_df (ip4_header_t * ip4)
 {
   ip4->flags_and_fragment_offset |=
     clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT);
 }

 always_inline void
 ip4_header_clear_df (ip4_header_t * ip4)
 {
   ip4->flags_and_fragment_offset &=
     ~clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT);
 }

 always_inline u8
 ip4_header_get_df (const ip4_header_t * ip4)
 {
   return (! !(ip4->flags_and_fragment_offset &
 	      clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT)));
 }

 static inline uword
 ip4_header_checksum_is_valid (ip4_header_t * i)
 {
   return i->checksum == ip4_header_checksum (i);
 }

 #define ip4_partial_header_checksum_x1(ip0,sum0)			\
 do {									\
   if (BITS (ip_csum_t) > 32)						\
     {									\
       sum0 = ip0->checksum_data_64[0];					\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64[1]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64_32[0]);	\
     }									\
   else									\
     {									\
       sum0 = ip0->checksum_data_32[0];					\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[1]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[2]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[3]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[4]);	\
     }									\
 } while (0)

 #define ip4_partial_header_checksum_x2(ip0,ip1,sum0,sum1)		\
 do {									\
   if (BITS (ip_csum_t) > 32)						\
     {									\
       sum0 = ip0->checksum_data_64[0];					\
       sum1 = ip1->checksum_data_64[0];					\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64[1]);	\
       sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_64[1]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64_32[0]);	\
       sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_64_32[0]);	\
     }									\
   else									\
     {									\
       sum0 = ip0->checksum_data_32[0];					\
       sum1 = ip1->checksum_data_32[0];					\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[1]);	\
       sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[1]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[2]);	\
       sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[2]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[3]);	\
       sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[3]);	\
       sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[4]);	\
       sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[4]);	\
     }									\
 } while (0)

 always_inline uword
 ip4_address_is_multicast (const ip4_address_t * a)
 {
   return (a->data[0] & 0xf0) == 0xe0;
 }

 always_inline uword
 ip4_address_is_global_broadcast (const ip4_address_t * a)
 {
   return (a->as_u32) == 0xffffffff;
 }

 always_inline void
 ip4_multicast_address_set_for_group (ip4_address_t * a,
 				     ip_multicast_group_t g)
 {
   ASSERT ((u32) g < (1 << 28));
   a->as_u32 = clib_host_to_net_u32 ((0xe << 28) + g);
 }

 always_inline void
 ip4_multicast_ethernet_address (u8 * ethernet_address,
 				const ip4_address_t * a)
 {
   const u8 *d = a->as_u8;

   ethernet_address[0] = 0x01;
   ethernet_address[1] = 0x00;
   ethernet_address[2] = 0x5e;
   ethernet_address[3] = d[1] & 0x7f;
   ethernet_address[4] = d[2];
   ethernet_address[5] = d[3];
 }

 always_inline void
 ip4_tcp_reply_x1 (ip4_header_t * ip0, tcp_header_t * tcp0)
 {
   u32 src0, dst0;

   src0 = ip0->src_address.data_u32;
   dst0 = ip0->dst_address.data_u32;
   ip0->src_address.data_u32 = dst0;
   ip0->dst_address.data_u32 = src0;

   src0 = tcp0->src;
   dst0 = tcp0->dst;
   tcp0->src = dst0;
   tcp0->dst = src0;
 }

 always_inline void
 ip4_tcp_reply_x2 (ip4_header_t * ip0, ip4_header_t * ip1,
 		  tcp_header_t * tcp0, tcp_header_t * tcp1)
 {
   u32 src0, dst0, src1, dst1;

   src0 = ip0->src_address.data_u32;
   src1 = ip1->src_address.data_u32;
   dst0 = ip0->dst_address.data_u32;
   dst1 = ip1->dst_address.data_u32;
   ip0->src_address.data_u32 = dst0;
   ip1->src_address.data_u32 = dst1;
   ip0->dst_address.data_u32 = src0;
   ip1->dst_address.data_u32 = src1;

   src0 = tcp0->src;
   src1 = tcp1->src;
   dst0 = tcp0->dst;
   dst1 = tcp1->dst;
   tcp0->src = dst0;
   tcp1->src = dst1;
   tcp0->dst = src0;
   tcp1->dst = src1;
 }

 #endif /* included_ip4_packet_h */

 /*
  * 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.
	*/
	/*
	* ip4/packet.h: ip4 packet format
	*
	* 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_ip4_packet_h
	#define included_ip4_packet_h

	#include <vnet/ip/ip_packet.h> /* for ip_csum_t */
	#include <vnet/tcp/tcp_packet.h> /* for tcp_header_t */
	#include <vppinfra/byte_order.h> /* for clib_net_to_host_u16 */

	/* IP4 address which can be accessed either as 4 bytes
	or as a 32-bit number. */
	typedef union
	{
	u8 data[4];
	u32 data_u32;
	/* Aliases. */
	u8 as_u8[4];
	u16 as_u16[2];
	u32 as_u32;
	} ip4_address_t;

	typedef struct
	{
	/* IP address must be first for ip_interface_address_get_address() to work */
	ip4_address_t ip4_addr;
	u32 fib_index;
	} ip4_address_fib_t;

	always_inline void
	ip4_addr_fib_init (ip4_address_fib_t * addr_fib,
	const ip4_address_t * address, u32 fib_index)
	{
	clib_memcpy_fast (&addr_fib->ip4_addr, address,
	sizeof (addr_fib->ip4_addr));
	addr_fib->fib_index = fib_index;
	}

	/* (src,dst) pair of addresses as found in packet header. */
	typedef struct
	{
	ip4_address_t src, dst;
	} ip4_address_pair_t;

	typedef struct
	{
	ip4_address_t addr, mask;
	} ip4_address_and_mask_t;

	typedef union
	{
	struct
	{
	/* 4 bit packet length (in 32bit units) and version VVVVLLLL.
	e.g. for packets w/ no options ip_version_and_header_length == 0x45. */
	u8 ip_version_and_header_length;

	/* Type of service. */
	ip_dscp_t tos;

	/* Total layer 3 packet length including this header. */
	u16 length;

	/* Fragmentation ID. */
	u16 fragment_id;

	/* 3 bits of flags and 13 bits of fragment offset (in units
	of 8 byte quantities). */
	u16 flags_and_fragment_offset;
	#define IP4_HEADER_FLAG_MORE_FRAGMENTS (1 << 13)
	#define IP4_HEADER_FLAG_DONT_FRAGMENT (1 << 14)
	#define IP4_HEADER_FLAG_CONGESTION (1 << 15)

	/* Time to live decremented by router at each hop. */
	u8 ttl;

	/* Next level protocol packet. */
	u8 protocol;

	/* Checksum. */
	u16 checksum;

	/* Source and destination address. */
	union
	{
	struct
	{
	ip4_address_t src_address, dst_address;
	};
	ip4_address_pair_t address_pair;
	};
	};

	/* For checksumming we'll want to access IP header in word sized chunks. */
	/* For 64 bit machines. */
	/* INDENT-OFF */
	CLIB_PACKED (struct {
	u64 checksum_data_64[2];
	u32 checksum_data_64_32[1];
	});
	/* INDENT-ON */

	/* For 32 bit machines. */
	/* INDENT-OFF */
	CLIB_PACKED (struct {
	u32 checksum_data_32[5];
	});
	/* INDENT-ON */
	} ip4_header_t;

	/* Value of ip_version_and_header_length for packets w/o options. */
	#define IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS \
	((4 << 4) \| (sizeof (ip4_header_t) / sizeof (u32)))

	#define IP4_ROUTER_ALERT_OPTION 20

	always_inline u16
	ip4_get_fragment_offset (const ip4_header_t * i)
	{
	return clib_net_to_host_u16 (i->flags_and_fragment_offset) & 0x1fff;
	}

	always_inline u16
	ip4_get_fragment_more (const ip4_header_t * i)
	{
	return clib_net_to_host_u16 (i->flags_and_fragment_offset) &
	IP4_HEADER_FLAG_MORE_FRAGMENTS;
	}

	always_inline int
	ip4_is_fragment (const ip4_header_t * i)
	{
	return (i->flags_and_fragment_offset &
	clib_net_to_host_u16 (0x1fff \| IP4_HEADER_FLAG_MORE_FRAGMENTS));
	}

	always_inline int
	ip4_is_first_fragment (const ip4_header_t * i)
	{
	return (i->flags_and_fragment_offset &
	clib_net_to_host_u16 (0x1fff \| IP4_HEADER_FLAG_MORE_FRAGMENTS)) ==
	clib_net_to_host_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS);
	}

	/* Fragment offset in bytes. */
	always_inline int
	ip4_get_fragment_offset_bytes (const ip4_header_t * i)
	{
	return 8 * ip4_get_fragment_offset (i);
	}

	always_inline int
	ip4_header_bytes (const ip4_header_t * i)
	{
	return sizeof (u32) * (i->ip_version_and_header_length & 0xf);
	}

	always_inline void *
	ip4_next_header (ip4_header_t * i)
	{
	return (void *) i + ip4_header_bytes (i);
	}

	always_inline u16
	ip4_header_checksum (ip4_header_t * i)
	{
	int option_len = (i->ip_version_and_header_length & 0xf) - 5;
	uword sum = 0;
	#if uword_bits == 64
	u32 iphdr = (u32 ) i;

	sum += iphdr[0];
	sum += iphdr[1];
	sum += (u16 ) (iphdr + 2);
	/* skip checksum */
	sum += iphdr[3];
	sum += iphdr[4];

	if (PREDICT_FALSE (option_len > 0))
	switch (option_len)
	{
	case 10:
	sum += iphdr[14];
	case 9:
	sum += iphdr[13];
	case 8:
	sum += iphdr[12];
	case 7:
	sum += iphdr[11];
	case 6:
	sum += iphdr[10];
	case 5:
	sum += iphdr[9];
	case 4:
	sum += iphdr[8];
	case 3:
	sum += iphdr[7];
	case 2:
	sum += iphdr[6];
	case 1:
	sum += iphdr[5];
	default:
	break;
	}

	sum = ((u32) sum) + (sum >> 32);
	#else
	u16 iphdr = (u16 ) i;

	sum += iphdr[0];
	sum += iphdr[1];
	sum += iphdr[2];
	sum += iphdr[3];
	sum += iphdr[4];
	/* skip checksum */
	sum += iphdr[6];
	sum += iphdr[7];
	sum += iphdr[8];
	sum += iphdr[9];

	if (PREDICT_FALSE (option_len > 0))
	switch (option_len)
	{
	case 10:
	sum += iphdr[28];
	sum += iphdr[29];
	case 9:
	sum += iphdr[26];
	sum += iphdr[27];
	case 8:
	sum += iphdr[24];
	sum += iphdr[25];
	case 7:
	sum += iphdr[22];
	sum += iphdr[23];
	case 6:
	sum += iphdr[20];
	sum += iphdr[21];
	case 5:
	sum += iphdr[18];
	sum += iphdr[19];
	case 4:
	sum += iphdr[16];
	sum += iphdr[17];
	case 3:
	sum += iphdr[14];
	sum += iphdr[15];
	case 2:
	sum += iphdr[12];
	sum += iphdr[13];
	case 1:
	sum += iphdr[10];
	sum += iphdr[11];
	default:
	break;
	}
	#endif

	sum = ((u16) sum) + (sum >> 16);
	sum = ((u16) sum) + (sum >> 16);
	return ~((u16) sum);
	}

	always_inline void
	ip4_header_set_dscp (ip4_header_t * ip4, ip_dscp_t dscp)
	{
	ip4->tos &= ~0xfc;
	/* not masking the dscp value to save th instruction
	* it shouldn't b necessary since the argument is an enum
	* whose range is therefore constrained in the CP. in the
	* DP it will have been taken from another packet, so again
	* constrained in value */
	ip4->tos \|= dscp << IP_PACKET_TC_FIELD_DSCP_BIT_SHIFT;
	}

	always_inline void
	ip4_header_set_ecn (ip4_header_t * ip4, ip_ecn_t ecn)
	{
	ip4->tos &= ~IP_PACKET_TC_FIELD_ECN_MASK;
	ip4->tos \|= ecn;
	}

	always_inline void
	ip4_header_set_ecn_w_chksum (ip4_header_t * ip4, ip_ecn_t ecn)
	{
	ip_csum_t sum = ip4->checksum;
	u8 old = ip4->tos;
	u8 new = (old & ~IP_PACKET_TC_FIELD_ECN_MASK) \| ecn;

	sum = ip_csum_update (sum, old, new, ip4_header_t, tos);
	ip4->checksum = ip_csum_fold (sum);
	ip4->tos = new;
	}

	always_inline ip_dscp_t
	ip4_header_get_dscp (const ip4_header_t * ip4)
	{
	return (ip4->tos >> IP_PACKET_TC_FIELD_DSCP_BIT_SHIFT);
	}

	always_inline ip_ecn_t
	ip4_header_get_ecn (const ip4_header_t * ip4)
	{
	return (ip4->tos & IP_PACKET_TC_FIELD_ECN_MASK);
	}

	always_inline void
	ip4_header_set_df (ip4_header_t * ip4)
	{
	ip4->flags_and_fragment_offset \|=
	clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT);
	}

	always_inline void
	ip4_header_clear_df (ip4_header_t * ip4)
	{
	ip4->flags_and_fragment_offset &=
	~clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT);
	}

	always_inline u8
	ip4_header_get_df (const ip4_header_t * ip4)
	{
	return (! !(ip4->flags_and_fragment_offset &
	clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT)));
	}

	static inline uword
	ip4_header_checksum_is_valid (ip4_header_t * i)
	{
	return i->checksum == ip4_header_checksum (i);
	}

	#define ip4_partial_header_checksum_x1(ip0,sum0) \
	do { \
	if (BITS (ip_csum_t) > 32) \
	{ \
	sum0 = ip0->checksum_data_64[0]; \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64[1]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64_32[0]); \
	} \
	else \
	{ \
	sum0 = ip0->checksum_data_32[0]; \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[1]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[2]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[3]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[4]); \
	} \
	} while (0)

	#define ip4_partial_header_checksum_x2(ip0,ip1,sum0,sum1) \
	do { \
	if (BITS (ip_csum_t) > 32) \
	{ \
	sum0 = ip0->checksum_data_64[0]; \
	sum1 = ip1->checksum_data_64[0]; \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64[1]); \
	sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_64[1]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_64_32[0]); \
	sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_64_32[0]); \
	} \
	else \
	{ \
	sum0 = ip0->checksum_data_32[0]; \
	sum1 = ip1->checksum_data_32[0]; \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[1]); \
	sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[1]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[2]); \
	sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[2]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[3]); \
	sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[3]); \
	sum0 = ip_csum_with_carry (sum0, ip0->checksum_data_32[4]); \
	sum1 = ip_csum_with_carry (sum1, ip1->checksum_data_32[4]); \
	} \
	} while (0)

	always_inline uword
	ip4_address_is_multicast (const ip4_address_t * a)
	{
	return (a->data[0] & 0xf0) == 0xe0;
	}

	always_inline uword
	ip4_address_is_global_broadcast (const ip4_address_t * a)
	{
	return (a->as_u32) == 0xffffffff;
	}

	always_inline void
	ip4_multicast_address_set_for_group (ip4_address_t * a,
	ip_multicast_group_t g)
	{
	ASSERT ((u32) g < (1 << 28));
	a->as_u32 = clib_host_to_net_u32 ((0xe << 28) + g);
	}

	always_inline void
	ip4_multicast_ethernet_address (u8 * ethernet_address,
	const ip4_address_t * a)
	{
	const u8 *d = a->as_u8;

	ethernet_address[0] = 0x01;
	ethernet_address[1] = 0x00;
	ethernet_address[2] = 0x5e;
	ethernet_address[3] = d[1] & 0x7f;
	ethernet_address[4] = d[2];
	ethernet_address[5] = d[3];
	}

	always_inline void
	ip4_tcp_reply_x1 (ip4_header_t * ip0, tcp_header_t * tcp0)
	{
	u32 src0, dst0;

	src0 = ip0->src_address.data_u32;
	dst0 = ip0->dst_address.data_u32;
	ip0->src_address.data_u32 = dst0;
	ip0->dst_address.data_u32 = src0;

	src0 = tcp0->src;
	dst0 = tcp0->dst;
	tcp0->src = dst0;
	tcp0->dst = src0;
	}

	always_inline void
	ip4_tcp_reply_x2 (ip4_header_t * ip0, ip4_header_t * ip1,
	tcp_header_t * tcp0, tcp_header_t * tcp1)
	{
	u32 src0, dst0, src1, dst1;

	src0 = ip0->src_address.data_u32;
	src1 = ip1->src_address.data_u32;
	dst0 = ip0->dst_address.data_u32;
	dst1 = ip1->dst_address.data_u32;
	ip0->src_address.data_u32 = dst0;
	ip1->src_address.data_u32 = dst1;
	ip0->dst_address.data_u32 = src0;
	ip1->dst_address.data_u32 = src1;

	src0 = tcp0->src;
	src1 = tcp1->src;
	dst0 = tcp0->dst;
	dst1 = tcp1->dst;
	tcp0->src = dst0;
	tcp1->src = dst1;
	tcp0->dst = src0;
	tcp1->dst = src1;
	}

	#endif /* included_ip4_packet_h */

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