text: /**
   * @file
   *
   * IPv6 version of ICMP, as per RFC 4443.
   */
  
  /*
   * Copyright (c) 2010 Inico Technologies Ltd.
   * 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: Ivan Delamer <delamer@inicotech.com>
   *
   *
   * Please coordinate changes and requests with Ivan Delamer
   * <delamer@inicotech.com>
   */
  
  #include "lwip/opt.h"
  
  #if LWIP_ICMP6 && LWIP_IPV6 /* don't build if not configured for use in lwipopts.h */
  
  #include "lwip/icmp6.h"
  #include "lwip/ip6.h"
  #include "lwip/ip6_addr.h"
  #include "lwip/inet_chksum.h"
  #include "lwip/pbuf.h"
  #include "lwip/netif.h"
  #include "lwip/nd6.h"
  #include "lwip/mld6.h"
  #include "lwip/ip.h"
  #include "lwip/stats.h"
  
  #include <string.h>
  
  #ifndef LWIP_ICMP6_DATASIZE
  #define LWIP_ICMP6_DATASIZE   8
  #endif
  #if LWIP_ICMP6_DATASIZE == 0
  #define LWIP_ICMP6_DATASIZE   8
  #endif
  
  /* Forward declarations */
  static void icmp6_send_response(struct pbuf *p, u8_t code, u32_t data, u8_t type);
  
  #if LWIP_CONNECTION_PROXY
  static ping6_proxy_fn ping6_proxy_accept_callback;
  static void *ping6_proxy_accept_arg;
  #endif
  
  
  /**
   * Process an input ICMPv6 message. Called by ip6_input.
   *
   * Will generate a reply for echo requests. Other messages are forwarded
   * to nd6_input, or mld6_input.
   *
   * @param p the mld packet, p->payload pointing to the icmpv6 header
   * @param inp the netif on which this packet was received
   */
  void
  icmp6_input(struct pbuf *p, struct netif *inp)
  {
    struct icmp6_hdr *icmp6hdr;
    struct pbuf * r;
    ip6_addr_t * reply_src;
  
    ICMP6_STATS_INC(icmp6.recv);
  
    /* Check that ICMPv6 header fits in payload */
    if (p->len < sizeof(struct icmp6_hdr)) {
      /* drop short packets */
      pbuf_free(p);
      ICMP6_STATS_INC(icmp6.lenerr);
      ICMP6_STATS_INC(icmp6.drop);
      return;
    }
  
    icmp6hdr = (struct icmp6_hdr *)p->payload;
  
  #if CHECKSUM_CHECK_ICMP6
    if (ip6_chksum_pseudo(p, IP6_NEXTH_ICMP6, p->tot_len, ip6_current_src_addr(),
                          ip6_current_dest_addr()) != 0) {
      /* Checksum failed */
      pbuf_free(p);
      ICMP6_STATS_INC(icmp6.chkerr);
      ICMP6_STATS_INC(icmp6.drop);
      return;
    }
  #endif /* CHECKSUM_CHECK_ICMP6 */
  
    switch (icmp6hdr->type) {
    case ICMP6_TYPE_NA: /* Neighbor advertisement */
    case ICMP6_TYPE_NS: /* Neighbor solicitation */
    case ICMP6_TYPE_RA: /* Router advertisement */
    case ICMP6_TYPE_RD: /* Redirect */
    case ICMP6_TYPE_PTB: /* Packet too big */
      nd6_input(p, inp);
      return;
      break;
    case ICMP6_TYPE_RS:
  #if LWIP_IPV6_FORWARD
      /* TODO implement router functionality */
  #endif
      break;
  #if LWIP_IPV6_MLD
    case ICMP6_TYPE_MLQ:
    case ICMP6_TYPE_MLR:
    case ICMP6_TYPE_MLD:
      mld6_input(p, inp);
      return;
      break;
  #endif
    case ICMP6_TYPE_EREQ:
  #if !LWIP_MULTICAST_PING
      /* multicast destination address? */
      if (ip6_addr_ismulticast(ip6_current_dest_addr())) {
        /* drop */
        pbuf_free(p);
        ICMP6_STATS_INC(icmp6.drop);
        return;
      }
  #endif /* LWIP_MULTICAST_PING */
  
      /* Allocate reply. */
      r = pbuf_alloc(PBUF_IP, p->tot_len, PBUF_RAM);
      if (r == NULL) {
        /* drop */
        pbuf_free(p);
        ICMP6_STATS_INC(icmp6.memerr);
        return;
      }
  
      /* Copy echo request. */
      if (pbuf_copy(r, p) != ERR_OK) {
        /* drop */
        pbuf_free(p);
        pbuf_free(r);
        ICMP6_STATS_INC(icmp6.err);
        return;
      }
  
      /* Determine reply source IPv6 address. */
  #if LWIP_MULTICAST_PING
      if (ip6_addr_ismulticast(ip6_current_dest_addr())) {
        reply_src = ip6_select_source_address(inp, ip6_current_src_addr());
        if (reply_src == NULL) {
          /* drop */
          pbuf_free(p);
          pbuf_free(r);
          ICMP6_STATS_INC(icmp6.rterr);
          return;
        }
      }
      else
  #endif /* LWIP_MULTICAST_PING */
      {
        reply_src = ip6_current_dest_addr();
      }
  
      /* Set fields in reply. */
      ((struct icmp6_echo_hdr *)(r->payload))->type = ICMP6_TYPE_EREP;
      ((struct icmp6_echo_hdr *)(r->payload))->chksum = 0;
  #if CHECKSUM_GEN_ICMP6
      ((struct icmp6_echo_hdr *)(r->payload))->chksum = ip6_chksum_pseudo(r,
          IP6_NEXTH_ICMP6, r->tot_len, reply_src, ip6_current_src_addr());
  #endif /* CHECKSUM_GEN_ICMP6 */
  
      /* Send reply. */
      ICMP6_STATS_INC(icmp6.xmit);
      ip6_output_if(r, reply_src, ip6_current_src_addr(),
          LWIP_ICMP6_HL, 0, IP6_NEXTH_ICMP6, inp);
      pbuf_free(r);
  
      break;
    default:
      ICMP6_STATS_INC(icmp6.proterr);
      ICMP6_STATS_INC(icmp6.drop);
      break;
    }
  
    pbuf_free(p);
  }
  
  
  #if LWIP_CONNECTION_PROXY
  
  void
  ping6_proxy_accept(ping6_proxy_fn callback, void *arg)
  {
    ping6_proxy_accept_callback = callback;
    ping6_proxy_accept_arg = arg;
  }
  
  
  void
  icmp6_proxy_input(struct pbuf *p, struct netif *inp)
  {
    struct icmp6_hdr *icmp6hdr;
  # ifdef VBOX
    (void)inp;
  # endif
  
    ICMP6_STATS_INC(icmp6.recv);
  
    /* Check that ICMPv6 header fits in payload */
    if (p->len < sizeof(struct icmp6_hdr)) {
      /* drop short packets */
      pbuf_free(p);
      ICMP6_STATS_INC(icmp6.lenerr);
      ICMP6_STATS_INC(icmp6.drop);
      return;
    }
  
    icmp6hdr = (struct icmp6_hdr *)p->payload;
    if (ip6_chksum_pseudo(p, IP6_NEXTH_ICMP6, p->tot_len, ip6_current_src_addr(),
                          ip6_current_dest_addr()) != 0) {
      /* Checksum failed */
      pbuf_free(p);
      ICMP6_STATS_INC(icmp6.chkerr);
      ICMP6_STATS_INC(icmp6.drop);
      return;
    }
  
    switch (icmp6hdr->type) {
  
    case ICMP6_TYPE_EREQ:
      if (ping6_proxy_accept_callback != NULL) {
        (*ping6_proxy_accept_callback)(ping6_proxy_accept_arg, p);
        return;
      }
      ICMP6_STATS_INC(icmp6.drop);
      break;
  
    case ICMP6_TYPE_EREP:
      /* ignore silently */
      ICMP6_STATS_INC(icmp6.drop);
      break;
  
    default:
      ICMP6_STATS_INC(icmp6.drop);
      break;
    }
  
    pbuf_free(p);
  }
  #endif /* LWIP_CONNECTION_PROXY */
  
  /**
   * Send an icmpv6 'destination unreachable' packet.
   *
   * @param p the input packet for which the 'unreachable' should be sent,
   *          p->payload pointing to the IPv6 header
   * @param c ICMPv6 code for the unreachable type
   */
  void
  icmp6_dest_unreach(struct pbuf *p, enum icmp6_dur_code c)
  {
    icmp6_send_response(p, c, 0, ICMP6_TYPE_DUR);
  }
  
  /**
   * Send an icmpv6 'packet too big' packet.
   *
   * @param p the input packet for which the 'packet too big' should be sent,
   *          p->payload pointing to the IPv6 header
   * @param mtu the maximum mtu that we can accept
   */
  void
  icmp6_packet_too_big(struct pbuf *p, u32_t mtu)
  {
    icmp6_send_response(p, 0, mtu, ICMP6_TYPE_PTB);
  }
  
  /**
   * Send an icmpv6 'time exceeded' packet.
   *
   * @param p the input packet for which the 'unreachable' should be sent,
   *          p->payload pointing to the IPv6 header
   * @param c ICMPv6 code for the time exceeded type
   */
  void
  icmp6_time_exceeded(struct pbuf *p, enum icmp6_te_code c)
  {
    icmp6_send_response(p, c, 0, ICMP6_TYPE_TE);
  }
  
  /**
   * Send an icmpv6 'parameter problem' packet.
   *
   * @param p the input packet for which the 'param problem' should be sent,
   *          p->payload pointing to the IP header
   * @param c ICMPv6 code for the param problem type
   * @param pointer the pointer to the byte where the parameter is found
   */
  void
  icmp6_param_problem(struct pbuf *p, enum icmp6_pp_code c, u32_t pointer)
  {
    icmp6_send_response(p, c, pointer, ICMP6_TYPE_PP);
  }
  
  /**
   * Send an ICMPv6 packet in response to an incoming packet.
   *
   * @param p the input packet for which the response should be sent,
   *          p->payload pointing to the IPv6 header
   * @param code Code of the ICMPv6 header
   * @param data Additional 32-bit parameter in the ICMPv6 header
   * @param type Type of the ICMPv6 header
   */
  static void
  icmp6_send_response(struct pbuf *p, u8_t code, u32_t data, u8_t type)
  {
    struct pbuf *q;
    struct icmp6_hdr *icmp6hdr;
    ip6_addr_t *reply_src, *reply_dest;
    ip6_addr_t reply_src_local, reply_dest_local;
    struct ip6_hdr *ip6hdr;
    struct netif *netif;
  
    /* ICMPv6 header + IPv6 header + data */
    q = pbuf_alloc(PBUF_IP, sizeof(struct icmp6_hdr) + IP6_HLEN + LWIP_ICMP6_DATASIZE,
                   PBUF_RAM);
    if (q == NULL) {
      LWIP_DEBUGF(ICMP_DEBUG, ("icmp_time_exceeded: failed to allocate pbuf for ICMPv6 packet.\n"));
      ICMP6_STATS_INC(icmp6.memerr);
      return;
    }
    LWIP_ASSERT("check that first pbuf can hold icmp 6message",
               (q->len >= (sizeof(struct icmp6_hdr) + IP6_HLEN + LWIP_ICMP6_DATASIZE)));
  
    icmp6hdr = (struct icmp6_hdr *)q->payload;
    icmp6hdr->type = type;
    icmp6hdr->code = code;
    icmp6hdr->data = data;
  
    /* copy fields from original packet */
    SMEMCPY((u8_t *)q->payload + sizeof(struct icmp6_hdr), (u8_t *)p->payload,
            IP6_HLEN + LWIP_ICMP6_DATASIZE);
  
    /* Get the destination address and netif for this ICMP message. */
    if ((ip_current_netif() == NULL) ||
        ((code == ICMP6_TE_FRAG) && (type == ICMP6_TYPE_TE))) {
      /* Special case, as ip6_current_xxx is either NULL, or points
       * to a different packet than the one that expired.
       * We must use the addresses that are stored in the expired packet. */
      ip6hdr = (struct ip6_hdr *)p->payload;
      /* copy from packed address to aligned address */
      ip6_addr_copy(reply_dest_local, ip6hdr->src);
      ip6_addr_copy(reply_src_local, ip6hdr->dest);
      reply_dest = &reply_dest_local;
      reply_src = &reply_src_local;
      netif = ip6_route(reply_src, reply_dest);
      if (netif == NULL) {
        /* drop */
        pbuf_free(q);
        ICMP6_STATS_INC(icmp6.rterr);
        return;
      }
    }
    else {
      netif = ip_current_netif();
      reply_dest = ip6_current_src_addr();
  
      /* Select an address to use as source. */
      reply_src = ip6_select_source_address(netif, reply_dest);
      if (reply_src == NULL) {
        /* drop */
        pbuf_free(q);
        ICMP6_STATS_INC(icmp6.rterr);
        return;
      }
    }
  
    /* calculate checksum */
    icmp6hdr->chksum = 0;
  #if CHECKSUM_GEN_ICMP6
    icmp6hdr->chksum = ip6_chksum_pseudo(q, IP6_NEXTH_ICMP6, q->tot_len,
      reply_src, reply_dest);
  #endif /* CHECKSUM_GEN_ICMP6 */
  
    ICMP6_STATS_INC(icmp6.xmit);
    ip6_output_if(q, reply_src, reply_dest, LWIP_ICMP6_HL, 0, IP6_NEXTH_ICMP6, netif);
    pbuf_free(q);
  }
  
  #endif /* LWIP_ICMP6 && LWIP_IPV6 */
  