text: /**
   * @file
   * IPv4 API
   */
  
  /*
   * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice,
   *    this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
   * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
   * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * This file is part of the lwIP TCP/IP stack.
   *
   * Author: Adam Dunkels <adam@sics.se>
   *
   */
  #ifndef LWIP_HDR_IP4_H
  #define LWIP_HDR_IP4_H
  
  #include "lwip/opt.h"
  
  #if LWIP_IPV4
  
  #include "lwip/def.h"
  #include "lwip/pbuf.h"
  #include "lwip/ip4_addr.h"
  #include "lwip/err.h"
  #include "lwip/netif.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #ifdef LWIP_HOOK_IP4_ROUTE_SRC
  #define LWIP_IPV4_SRC_ROUTING   1
  #else
  #define LWIP_IPV4_SRC_ROUTING   0
  #endif
  
  /** Currently, the function ip_output_if_opt() is only used with IGMP */
  #define IP_OPTIONS_SEND   (LWIP_IPV4 && LWIP_IGMP)
  
  #define IP_HLEN 20
  
  
  #ifdef PACK_STRUCT_USE_INCLUDES
  #  include "arch/bpstruct.h"
  #endif
  PACK_STRUCT_BEGIN
  struct ip_hdr
  {
      /* version / header length */
      PACK_STRUCT_FLD_8(u8_t _v_hl);
      /* type of service */
      PACK_STRUCT_FLD_8(u8_t _tos);
      /* total length */
      PACK_STRUCT_FIELD(u16_t _len);
      /* identification */
      PACK_STRUCT_FIELD(u16_t _id);
      /* fragment offset field */
      PACK_STRUCT_FIELD(u16_t _offset);
  #define IP_RF 0x8000U        /* reserved fragment flag */
  #define IP_DF 0x4000U        /* don't fragment flag */
  #define IP_MF 0x2000U        /* more fragments flag */
  #define IP_OFFMASK 0x1fffU   /* mask for fragmenting bits */
      /* time to live */
      PACK_STRUCT_FLD_8(u8_t _ttl);
      /* protocol*/
      PACK_STRUCT_FLD_8(u8_t _proto);
      /* checksum */
      PACK_STRUCT_FIELD(u16_t _chksum);
      /* source and destination IP addresses */
      PACK_STRUCT_FLD_S(ip4_addr_p_t src);
      PACK_STRUCT_FLD_S(ip4_addr_p_t dest);
  } PACK_STRUCT_STRUCT;
  PACK_STRUCT_END
  #ifdef PACK_STRUCT_USE_INCLUDES
  #  include "arch/epstruct.h"
  #endif
  
  #define IPH_V(hdr)  ((hdr)->_v_hl >> 4)
  #define IPH_HL(hdr) ((hdr)->_v_hl & 0x0f)
  #define IPH_TOS(hdr) ((hdr)->_tos)
  #define IPH_LEN(hdr) ((hdr)->_len)
  #define IPH_ID(hdr) ((hdr)->_id)
  #define IPH_OFFSET(hdr) ((hdr)->_offset)
  #define IPH_TTL(hdr) ((hdr)->_ttl)
  #define IPH_PROTO(hdr) ((hdr)->_proto)
  #define IPH_CHKSUM(hdr) ((hdr)->_chksum)
  
  #define IPH_VHL_SET(hdr, v, hl) (hdr)->_v_hl = (u8_t)((((v) << 4) | (hl)))
  #define IPH_TOS_SET(hdr, tos) (hdr)->_tos = (tos)
  #define IPH_LEN_SET(hdr, len) (hdr)->_len = (len)
  #define IPH_ID_SET(hdr, id) (hdr)->_id = (id)
  #define IPH_OFFSET_SET(hdr, off) (hdr)->_offset = (off)
  #define IPH_TTL_SET(hdr, ttl) (hdr)->_ttl = (u8_t)(ttl)
  #define IPH_PROTO_SET(hdr, proto) (hdr)->_proto = (u8_t)(proto)
  #define IPH_CHKSUM_SET(hdr, chksum) (hdr)->_chksum = (chksum)
  
  #define ip_init() /* Compatibility define, no init needed. */
  struct netif *ip4_route(const ip4_addr_t *dest);
  #if LWIP_IPV4_SRC_ROUTING
  struct netif *ip4_route_src(const ip4_addr_t *dest, const ip4_addr_t *src);
  #else /* LWIP_IPV4_SRC_ROUTING */
  #define ip4_route_src(dest, src) ip4_route(dest)
  #endif /* LWIP_IPV4_SRC_ROUTING */
  err_t ip4_input(struct pbuf *p, struct netif *inp);
  err_t ip4_output(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
                   u8_t ttl, u8_t tos, u8_t proto);
  err_t ip4_output_if(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
                      u8_t ttl, u8_t tos, u8_t proto, struct netif *netif);
  err_t ip4_output_if_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
                          u8_t ttl, u8_t tos, u8_t proto, struct netif *netif);
  #if LWIP_NETIF_HWADDRHINT
  err_t ip4_output_hinted(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
                          u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint);
  #endif /* LWIP_NETIF_HWADDRHINT */
  #if IP_OPTIONS_SEND
  err_t ip4_output_if_opt(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
                          u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
                          u16_t optlen);
  err_t ip4_output_if_opt_src(struct pbuf *p, const ip4_addr_t *src, const ip4_addr_t *dest,
                              u8_t ttl, u8_t tos, u8_t proto, struct netif *netif, void *ip_options,
                              u16_t optlen);
  #endif /* IP_OPTIONS_SEND */
  
  #if LWIP_MULTICAST_TX_OPTIONS
  void  ip4_set_default_multicast_netif(struct netif* default_multicast_netif);
  #endif /* LWIP_MULTICAST_TX_OPTIONS */
  
  #define ip4_netif_get_local_ip(netif) (((netif) != NULL) ? netif_ip_addr4(netif) : NULL)
  
  #if IP_DEBUG
  void ip4_debug_print(struct pbuf *p);
  #else
  #define ip4_debug_print(p)
  #endif /* IP_DEBUG */
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* LWIP_IPV4 */
  
  #endif /* LWIP_HDR_IP_H */
  
  
  