text: /**
   * @file
   * IP 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_IP_H
  #define LWIP_HDR_IP_H
  
  #include "lwip/opt.h"
  
  #include "lwip/def.h"
  #include "lwip/pbuf.h"
  #include "lwip/ip_addr.h"
  #include "lwip/err.h"
  #include "lwip/netif.h"
  #include "lwip/ip4.h"
  #include "lwip/ip6.h"
  #include "lwip/prot/ip.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* This is passed as the destination address to ip_output_if (not
     to ip_output), meaning that an IP header already is constructed
     in the pbuf. This is used when TCP retransmits. */
  #define LWIP_IP_HDRINCL  NULL
  
  /** pbufs passed to IP must have a ref-count of 1 as their payload pointer
      gets altered as the packet is passed down the stack */
  #ifndef LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX
  #define LWIP_IP_CHECK_PBUF_REF_COUNT_FOR_TX(p) LWIP_ASSERT("p->ref == 1", (p)->ref == 1)
  #endif
  
  #if LWIP_NETIF_HWADDRHINT
  #define IP_PCB_ADDRHINT ;u8_t addr_hint
  #else
  #define IP_PCB_ADDRHINT
  #endif /* LWIP_NETIF_HWADDRHINT */
  
  /** This is the common part of all PCB types. It needs to be at the
     beginning of a PCB type definition. It is located here so that
     changes to this common part are made in one location instead of
     having to change all PCB structs. */
  #define IP_PCB \
    /* ip addresses in network byte order */ \
    ip_addr_t local_ip; \
    ip_addr_t remote_ip; \
     /* Socket options */  \
    u8_t so_options;      \
     /* Type Of Service */ \
    u8_t tos;              \
    /* Time To Live */     \
    u8_t ttl               \
    /* link layer address resolution hint */ \
    IP_PCB_ADDRHINT
  
  struct ip_pcb {
  /* Common members of all PCB types */
    IP_PCB;
  };
  
  /*
   * Option flags per-socket. These are the same like SO_XXX in sockets.h
   */
  #define SOF_REUSEADDR     0x04U  /* allow local address reuse */
  #define SOF_KEEPALIVE     0x08U  /* keep connections alive */
  #define SOF_BROADCAST     0x20U  /* permit to send and to receive broadcast messages (see IP_SOF_BROADCAST option) */
  
  /* These flags are inherited (e.g. from a listen-pcb to a connection-pcb): */
  #define SOF_INHERITED   (SOF_REUSEADDR|SOF_KEEPALIVE)
  
  /** Global variables of this module, kept in a struct for efficient access using base+index. */
  struct ip_globals
  {
    /** The interface that accepted the packet for the current callback invocation. */
    struct netif *current_netif;
    /** The interface that received the packet for the current callback invocation. */
    struct netif *current_input_netif;
  #if LWIP_IPV4
    /** Header of the input packet currently being processed. */
    struct ip_hdr *current_ip4_header;
  #endif /* LWIP_IPV4 */
  #if LWIP_IPV6
    /** Header of the input IPv6 packet currently being processed. */
    struct ip6_hdr *current_ip6_header;
  #endif /* LWIP_IPV6 */
    /** Total header length of current_ip4/6_header (i.e. after this, the UDP/TCP header starts) */
    u16_t current_ip_header_tot_len;
    /** Source IP address of current_header */
    ip_addr_t current_iphdr_src;
    /** Destination IP address of current_header */
    ip_addr_t current_iphdr_dest;
  };
  extern struct ip_globals ip_data;
  
  
  /** Get the interface that accepted the current packet.
   * This may or may not be the receiving netif, depending on your netif/network setup.
   * This function must only be called from a receive callback (udp_recv,
   * raw_recv, tcp_accept). It will return NULL otherwise. */
  #define ip_current_netif()      (ip_data.current_netif)
  /** Get the interface that received the current packet.
   * This function must only be called from a receive callback (udp_recv,
   * raw_recv, tcp_accept). It will return NULL otherwise. */
  #define ip_current_input_netif() (ip_data.current_input_netif)
  /** Total header length of ip(6)_current_header() (i.e. after this, the UDP/TCP header starts) */
  #define ip_current_header_tot_len() (ip_data.current_ip_header_tot_len)
  /** Source IP address of current_header */
  #define ip_current_src_addr()   (&ip_data.current_iphdr_src)
  /** Destination IP address of current_header */
  #define ip_current_dest_addr()  (&ip_data.current_iphdr_dest)
  
  #if LWIP_IPV4 && LWIP_IPV6
  /** Get the IPv4 header of the current packet.
   * This function must only be called from a receive callback (udp_recv,
   * raw_recv, tcp_accept). It will return NULL otherwise. */
  #define ip4_current_header()     ((const struct ip_hdr*)(ip_data.current_ip4_header))
  /** Get the IPv6 header of the current packet.
   * This function must only be called from a receive callback (udp_recv,
   * raw_recv, tcp_accept). It will return NULL otherwise. */
  #define ip6_current_header()      ((const struct ip6_hdr*)(ip_data.current_ip6_header))
  /** Returns TRUE if the current IP input packet is IPv6, FALSE if it is IPv4 */
  #define ip_current_is_v6()        (ip6_current_header() != NULL)
  /** Source IPv6 address of current_header */
  #define ip6_current_src_addr()    (ip_2_ip6(&ip_data.current_iphdr_src))
  /** Destination IPv6 address of current_header */
  #define ip6_current_dest_addr()   (ip_2_ip6(&ip_data.current_iphdr_dest))
  /** Get the transport layer protocol */
  #define ip_current_header_proto() (ip_current_is_v6() ? \
                                     IP6H_NEXTH(ip6_current_header()) :\
                                     IPH_PROTO(ip4_current_header()))
  /** Get the transport layer header */
  #define ip_next_header_ptr()     ((const void*)((ip_current_is_v6() ? \
    (const u8_t*)ip6_current_header() : (const u8_t*)ip4_current_header())  + ip_current_header_tot_len()))
  
  /** Source IP4 address of current_header */
  #define ip4_current_src_addr()     (ip_2_ip4(&ip_data.current_iphdr_src))
  /** Destination IP4 address of current_header */
  #define ip4_current_dest_addr()    (ip_2_ip4(&ip_data.current_iphdr_dest))
  
  #elif LWIP_IPV4 /* LWIP_IPV4 && LWIP_IPV6 */
  
  /** Get the IPv4 header of the current packet.
   * This function must only be called from a receive callback (udp_recv,
   * raw_recv, tcp_accept). It will return NULL otherwise. */
  #define ip4_current_header()     ((const struct ip_hdr*)(ip_data.current_ip4_header))
  /** Always returns FALSE when only supporting IPv4 only */
  #define ip_current_is_v6()        0
  /** Get the transport layer protocol */
  #define ip_current_header_proto() IPH_PROTO(ip4_current_header())
  /** Get the transport layer header */
  #define ip_next_header_ptr()     ((const void*)((const u8_t*)ip4_current_header() + ip_current_header_tot_len()))
  /** Source IP4 address of current_header */
  #define ip4_current_src_addr()     (&ip_data.current_iphdr_src)
  /** Destination IP4 address of current_header */
  #define ip4_current_dest_addr()    (&ip_data.current_iphdr_dest)
  
  #elif LWIP_IPV6 /* LWIP_IPV4 && LWIP_IPV6 */
  
  /** Get the IPv6 header of the current packet.
   * This function must only be called from a receive callback (udp_recv,
   * raw_recv, tcp_accept). It will return NULL otherwise. */
  #define ip6_current_header()      ((const struct ip6_hdr*)(ip_data.current_ip6_header))
  /** Always returns TRUE when only supporting IPv6 only */
  #define ip_current_is_v6()        1
  /** Get the transport layer protocol */
  #define ip_current_header_proto() IP6H_NEXTH(ip6_current_header())
  /** Get the transport layer header */
  #define ip_next_header_ptr()     ((const void*)((const u8_t*)ip6_current_header()))
  /** Source IP6 address of current_header */
  #define ip6_current_src_addr()    (&ip_data.current_iphdr_src)
  /** Destination IP6 address of current_header */
  #define ip6_current_dest_addr()   (&ip_data.current_iphdr_dest)
  
  #endif /* LWIP_IPV6 */
  
  /** Union source address of current_header */
  #define ip_current_src_addr()    (&ip_data.current_iphdr_src)
  /** Union destination address of current_header */
  #define ip_current_dest_addr()   (&ip_data.current_iphdr_dest)
  
  /** Gets an IP pcb option (SOF_* flags) */
  #define ip_get_option(pcb, opt)   ((pcb)->so_options & (opt))
  /** Sets an IP pcb option (SOF_* flags) */
  #define ip_set_option(pcb, opt)   ((pcb)->so_options |= (opt))
  /** Resets an IP pcb option (SOF_* flags) */
  #define ip_reset_option(pcb, opt) ((pcb)->so_options &= ~(opt))
  
  #if LWIP_IPV4 && LWIP_IPV6
  /**
   * @ingroup ip
   * Output IP packet, netif is selected by source address
   */
  #define ip_output(p, src, dest, ttl, tos, proto) \
          (IP_IS_V6(dest) ? \
          ip6_output(p, ip_2_ip6(src), ip_2_ip6(dest), ttl, tos, proto) : \
          ip4_output(p, ip_2_ip4(src), ip_2_ip4(dest), ttl, tos, proto))
  /**
   * @ingroup ip
   * Output IP packet to specified interface
   */
  #define ip_output_if(p, src, dest, ttl, tos, proto, netif) \
          (IP_IS_V6(dest) ? \
          ip6_output_if(p, ip_2_ip6(src), ip_2_ip6(dest), ttl, tos, proto, netif) : \
          ip4_output_if(p, ip_2_ip4(src), ip_2_ip4(dest), ttl, tos, proto, netif))
  /**
   * @ingroup ip
   * Output IP packet to interface specifying source address
   */
  #define ip_output_if_src(p, src, dest, ttl, tos, proto, netif) \
          (IP_IS_V6(dest) ? \
          ip6_output_if_src(p, ip_2_ip6(src), ip_2_ip6(dest), ttl, tos, proto, netif) : \
          ip4_output_if_src(p, ip_2_ip4(src), ip_2_ip4(dest), ttl, tos, proto, netif))
  /** Output IP packet with addr_hint */
  #define ip_output_hinted(p, src, dest, ttl, tos, proto, addr_hint) \
          (IP_IS_V6(dest) ? \
          ip6_output_hinted(p, ip_2_ip6(src), ip_2_ip6(dest), ttl, tos, proto, addr_hint) : \
          ip4_output_hinted(p, ip_2_ip4(src), ip_2_ip4(dest), ttl, tos, proto, addr_hint))
  /**
   * @ingroup ip
   * Get netif for address combination. See \ref ip6_route and \ref ip4_route
   */
  #define ip_route(src, dest) \
          (IP_IS_V6(dest) ? \
          ip6_route(ip_2_ip6(src), ip_2_ip6(dest)) : \
          ip4_route_src(ip_2_ip4(dest), ip_2_ip4(src)))
  /**
   * @ingroup ip
   * Get netif for IP.
   */
  #define ip_netif_get_local_ip(netif, dest) (IP_IS_V6(dest) ? \
          ip6_netif_get_local_ip(netif, ip_2_ip6(dest)) : \
          ip4_netif_get_local_ip(netif))
  #define ip_debug_print(is_ipv6, p) ((is_ipv6) ? ip6_debug_print(p) : ip4_debug_print(p))
  
  err_t ip_input(struct pbuf *p, struct netif *inp);
  
  #elif LWIP_IPV4 /* LWIP_IPV4 && LWIP_IPV6 */
  
  #define ip_output(p, src, dest, ttl, tos, proto) \
          ip4_output(p, src, dest, ttl, tos, proto)
  #define ip_output_if(p, src, dest, ttl, tos, proto, netif) \
          ip4_output_if(p, src, dest, ttl, tos, proto, netif)
  #define ip_output_if_src(p, src, dest, ttl, tos, proto, netif) \
          ip4_output_if_src(p, src, dest, ttl, tos, proto, netif)
  #define ip_output_hinted(p, src, dest, ttl, tos, proto, addr_hint) \
          ip4_output_hinted(p, src, dest, ttl, tos, proto, addr_hint)
  #define ip_route(src, dest) \
          ip4_route_src(dest, src)
  #define ip_netif_get_local_ip(netif, dest) \
          ip4_netif_get_local_ip(netif)
  #define ip_debug_print(is_ipv6, p) ip4_debug_print(p)
  
  #define ip_input ip4_input
  
  #elif LWIP_IPV6 /* LWIP_IPV4 && LWIP_IPV6 */
  
  #define ip_output(p, src, dest, ttl, tos, proto) \
          ip6_output(p, src, dest, ttl, tos, proto)
  #define ip_output_if(p, src, dest, ttl, tos, proto, netif) \
          ip6_output_if(p, src, dest, ttl, tos, proto, netif)
  #define ip_output_if_src(p, src, dest, ttl, tos, proto, netif) \
          ip6_output_if_src(p, src, dest, ttl, tos, proto, netif)
  #define ip_output_hinted(p, src, dest, ttl, tos, proto, addr_hint) \
          ip6_output_hinted(p, src, dest, ttl, tos, proto, addr_hint)
  #define ip_route(src, dest) \
          ip6_route(src, dest)
  #define ip_netif_get_local_ip(netif, dest) \
          ip6_netif_get_local_ip(netif, dest)
  #define ip_debug_print(is_ipv6, p) ip6_debug_print(p)
  
  #define ip_input ip6_input
  
  #endif /* LWIP_IPV6 */
  
  #define ip_route_get_local_ip(src, dest, netif, ipaddr) do { \
    (netif) = ip_route(src, dest); \
    (ipaddr) = ip_netif_get_local_ip(netif, dest); \
  }while(0)
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* LWIP_HDR_IP_H */
  
  
  