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/*
 * Copyright (c) 2021-2022 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.
 */

#ifndef HICN_PROTOCOL_IPV4
#define HICN_PROTOCOL_IPV4

#include <hicn/util/ip_address.h>

#include <hicn/base.h>
#include <hicn/common.h>

/* Headers were adapted from linux' definitions in netinet/ip.h */

/*
 * The length of the IPV4 header struct must be 20 bytes.
 */
#define EXPECTED_IPV4_HDRLEN 20

typedef struct
{
  union
  {
    struct
    {
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
      u8 ihl : 4;
      u8 version : 4;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
      u8 version : 4;
      u8 ihl : 4;
#else
#error "Unsupported endianness"
#endif
    };

    u8 version_ihl;
  };
  u8 tos;

  /*
   * This is the total length of the IP packet, including the IP header.
   * NOTE: vriable len header size is currently not supported by the lib.
   */
  u16 len;

  u16 id;
  u16 frag_off;
  u8 ttl;
  u8 protocol;
  u16 csum;
  ipv4_address_t saddr;
  ipv4_address_t daddr;
} _ipv4_header_t;

#define ipv4_header_bytes(ipv4_header)                                        \
  (sizeof (u32) * (ipv4_header->version_ihl & 0xf))

#define IPV4_HDRLEN sizeof (_ipv4_header_t)
static_assert (EXPECTED_IPV4_HDRLEN == IPV4_HDRLEN,
	       "Size of IPV4 struct does not match its expected size.");

/*
 * The length of the IPV4 pseudo header struct must be 12 bytes.
 */
#define EXPECTED_IPV4_PSHDRLEN 12

typedef struct
{
  ipv4_address_t ip_src;
  ipv4_address_t ip_dst;
  u8 zero;
  u8 protocol;
  u16 size;
} ipv4_pseudo_header_t;

#define IPV4_PSHDRLEN sizeof (ipv4_pseudo_header_t)
static_assert (EXPECTED_IPV4_PSHDRLEN == IPV4_PSHDRLEN,
	       "Size of IPV4_PSHDR struct does not match its expected size.");

/* Default field values */
#define IPV4_DEFAULT_VERSION	    4
#define IPV4_DEFAULT_IHL	    5
#define IPV4_DEFAULT_TOS	    0
#define IPV4_DEFAULT_PAYLOAD_LENGTH 0
#define IPV4_DEFAULT_ID		    300
#define IPV4_DEFAULT_FRAG_OFF	    0x000
#define IPV4_DEFAULT_TTL	    64
#define IPV4_DEFAULT_PROTOCOL	    IPPROTO_TCP
#define IPV4_DEFAULT_SRC_IP	    0, 0, 0, 0
#define IPV4_DEFAULT_DST_IP	    0, 0, 0, 0

#endif /* HICN_PROTOCOL_IPV4 */

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