ip.c

lwip-1.4.0

             u8_t ttl, u8_t tos,
             u8_t proto, struct netif *netif)
{
#if IP_OPTIONS_SEND
  return ip_output_if_opt(p, src, dest, ttl, tos, proto, netif, NULL, 0);
}

/**
 * Same as ip_output_if() but with the possibility to include IP options:
 *
 * @ param ip_options pointer to the IP options, copied into the IP header
 * @ param optlen length of ip_options
 */
err_t ip_output_if_opt(struct pbuf *p, ip_addr_t *src, ip_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 */
  struct ip_hdr *iphdr;
  ip_addr_t dest_addr;
#if CHECKSUM_GEN_IP_INLINE
  u32_t chk_sum = 0;
#endif /* CHECKSUM_GEN_IP_INLINE */

  /* 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 */
  LWIP_ASSERT("p->ref == 1", p->ref == 1);

  snmp_inc_ipoutrequests();

  /* Should the IP header be generated or is it already included in p? */
  if (dest != IP_HDRINCL) {
    u16_t ip_hlen = IP_HLEN;
#if IP_OPTIONS_SEND
    u16_t optlen_aligned = 0;
    if (optlen != 0) {
#if CHECKSUM_GEN_IP_INLINE
      int i;
#endif /* CHECKSUM_GEN_IP_INLINE */
      /* round up to a multiple of 4 */
      optlen_aligned = ((optlen + 3) & ~3);
      ip_hlen += optlen_aligned;
      /* First write in the IP options */
      if (pbuf_header(p, optlen_aligned)) {
        LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_output_if_opt: not enough room for IP options in pbuf\n"));
        IP_STATS_INC(ip.err);
        snmp_inc_ipoutdiscards();
        return ERR_BUF;
      }
      MEMCPY(p->payload, ip_options, optlen);
      if (optlen < optlen_aligned) {
        /* zero the remaining bytes */
        memset(((char*)p->payload) + optlen, 0, optlen_aligned - optlen);
      }
#if CHECKSUM_GEN_IP_INLINE
      for (i = 0; i < optlen_aligned/2; i++) {
        chk_sum += ((u16_t*)p->payload)[i];
      }
#endif /* CHECKSUM_GEN_IP_INLINE */
    }
#endif /* IP_OPTIONS_SEND */
    /* generate IP header */
    if (pbuf_header(p, IP_HLEN)) {
      LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_LEVEL_SERIOUS, ("ip_output: not enough room for IP header in pbuf\n"));

      IP_STATS_INC(ip.err);
      snmp_inc_ipoutdiscards();
      return ERR_BUF;
    }

    iphdr = (struct ip_hdr *)p->payload;
    LWIP_ASSERT("check that first pbuf can hold struct ip_hdr",
               (p->len >= sizeof(struct ip_hdr)));

    IPH_TTL_SET(iphdr, ttl);
    IPH_PROTO_SET(iphdr, proto);
#if CHECKSUM_GEN_IP_INLINE
    chk_sum += LWIP_MAKE_U16(proto, ttl);
#endif /* CHECKSUM_GEN_IP_INLINE */

    /* dest cannot be NULL here */
    ip_addr_copy(iphdr->dest, *dest);
#if CHECKSUM_GEN_IP_INLINE
    chk_sum += ip4_addr_get_u32(&iphdr->dest) & 0xFFFF;
    chk_sum += ip4_addr_get_u32(&iphdr->dest) >> 16;
#endif /* CHECKSUM_GEN_IP_INLINE */

    IPH_VHLTOS_SET(iphdr, 4, ip_hlen / 4, tos);
#if CHECKSUM_GEN_IP_INLINE
    chk_sum += iphdr->_v_hl_tos;
#endif /* CHECKSUM_GEN_IP_INLINE */
    IPH_LEN_SET(iphdr, htons(p->tot_len));
#if CHECKSUM_GEN_IP_INLINE
    chk_sum += iphdr->_len;
#endif /* CHECKSUM_GEN_IP_INLINE */
    IPH_OFFSET_SET(iphdr, 0);
    IPH_ID_SET(iphdr, htons(ip_id));
#if CHECKSUM_GEN_IP_INLINE
    chk_sum += iphdr->_id;
#endif /* CHECKSUM_GEN_IP_INLINE */
    ++ip_id;

    if (ip_addr_isany(src)) {
      ip_addr_copy(iphdr->src, netif->ip_addr);
    } else {
      /* src cannot be NULL here */
      ip_addr_copy(iphdr->src, *src);
    }

#if CHECKSUM_GEN_IP_INLINE
    chk_sum += ip4_addr_get_u32(&iphdr->src) & 0xFFFF;
    chk_sum += ip4_addr_get_u32(&iphdr->src) >> 16;
    chk_sum = (chk_sum >> 16) + (chk_sum & 0xFFFF);
    chk_sum = (chk_sum >> 16) + chk_sum;
    chk_sum = ~chk_sum;
    iphdr->_chksum = chk_sum; /* network order */
#else /* CHECKSUM_GEN_IP_INLINE */
    IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP
    IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, ip_hlen));
#endif
#endif /* CHECKSUM_GEN_IP_INLINE */
  } else {
    /* IP header already included in p */
    iphdr = (struct ip_hdr *)p->payload;
    ip_addr_copy(dest_addr, iphdr->dest);
    dest = &dest_addr;
  }

  IP_STATS_INC(ip.xmit);

  LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num));
  ip_debug_print(p);

#if ENABLE_LOOPBACK
  if (ip_addr_cmp(dest, &netif->ip_addr)) {
    /* Packet to self, enqueue it for loopback */
    LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
    return netif_loop_output(netif, p, dest);
  }
#if LWIP_IGMP
  if ((p->flags & PBUF_FLAG_MCASTLOOP) != 0) {
    netif_loop_output(netif, p, dest);
  }
#endif /* LWIP_IGMP */
#endif /* ENABLE_LOOPBACK */
#if IP_FRAG
  /* don't fragment if interface has mtu set to 0 [loopif] */
  if (netif->mtu && (p->tot_len > netif->mtu)) {
    return ip_frag(p, netif, dest);
  }
#endif /* IP_FRAG */

  LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
  return netif->output(netif, p, dest);
}

/**
 * Simple interface to ip_output_if. It finds the outgoing network
 * interface and calls upon ip_output_if to do the actual work.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
            protocol header; if dest == IP_HDRINCL, p already includes an IP
            header and p->payload points to that IP header)
 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
 *         IP  address of the netif used to send is used as source address)
 * @param dest the destination IP address to send the packet to
 * @param ttl the TTL value to be set in the IP header
 * @param tos the TOS value to be set in the IP header
 * @param proto the PROTOCOL to be set in the IP header
 *
 * @return ERR_RTE if no route is found
 *         see ip_output_if() for more return values
 */
err_t
ip_output(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
          u8_t ttl, u8_t tos, u8_t proto)
{
  struct netif *netif;

  /* 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 */
  LWIP_ASSERT("p->ref == 1", p->ref == 1);

  if ((netif = ip_route(dest)) == NULL) {
    LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
      ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
    IP_STATS_INC(ip.rterr);
    return ERR_RTE;
  }

  return ip_output_if(p, src, dest, ttl, tos, proto, netif);
}

#if LWIP_NETIF_HWADDRHINT
/** Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint
 *  before calling ip_output_if.
 *
 * @param p the packet to send (p->payload points to the data, e.g. next
            protocol header; if dest == IP_HDRINCL, p already includes an IP
            header and p->payload points to that IP header)
 * @param src the source IP address to send from (if src == IP_ADDR_ANY, the
 *         IP  address of the netif used to send is used as source address)
 * @param dest the destination IP address to send the packet to
 * @param ttl the TTL value to be set in the IP header
 * @param tos the TOS value to be set in the IP header
 * @param proto the PROTOCOL to be set in the IP header
 * @param addr_hint address hint pointer set to netif->addr_hint before
 *        calling ip_output_if()
 *
 * @return ERR_RTE if no route is found
 *         see ip_output_if() for more return values
 */
err_t
ip_output_hinted(struct pbuf *p, ip_addr_t *src, ip_addr_t *dest,
          u8_t ttl, u8_t tos, u8_t proto, u8_t *addr_hint)
{
  struct netif *netif;
  err_t err;

  /* 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 */
  LWIP_ASSERT("p->ref == 1", p->ref == 1);

  if ((netif = ip_route(dest)) == NULL) {
    LWIP_DEBUGF(IP_DEBUG, ("ip_output: No route to %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
      ip4_addr1_16(dest), ip4_addr2_16(dest), ip4_addr3_16(dest), ip4_addr4_16(dest)));
    IP_STATS_INC(ip.rterr);
    return ERR_RTE;
  }

  netif->addr_hint = addr_hint;
  err = ip_output_if(p, src, dest, ttl, tos, proto, netif);
  netif->addr_hint = NULL;

  return err;
}
#endif /* LWIP_NETIF_HWADDRHINT*/

#if IP_DEBUG
/* Print an IP header by using LWIP_DEBUGF
 * @param p an IP packet, p->payload pointing to the IP header
 */
void
ip_debug_print(struct pbuf *p)
{
  struct ip_hdr *iphdr = (struct ip_hdr *)p->payload;
  u8_t *payload;

  payload = (u8_t *)iphdr + IP_HLEN;

  LWIP_DEBUGF(IP_DEBUG, ("IP header:\n"));
  LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  LWIP_DEBUGF(IP_DEBUG, ("|%2"S16_F" |%2"S16_F" |  0x%02"X16_F" |     %5"U16_F"     | (v, hl, tos, len)\n",
                    IPH_V(iphdr),
                    IPH_HL(iphdr),
                    IPH_TOS(iphdr),
                    ntohs(IPH_LEN(iphdr))));
  LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  LWIP_DEBUGF(IP_DEBUG, ("|    %5"U16_F"      |%"U16_F"%"U16_F"%"U16_F"|    %4"U16_F"   | (id, flags, offset)\n",
                    ntohs(IPH_ID(iphdr)),
                    ntohs(IPH_OFFSET(iphdr)) >> 15 & 1,
                    ntohs(IPH_OFFSET(iphdr)) >> 14 & 1,
                    ntohs(IPH_OFFSET(iphdr)) >> 13 & 1,
                    ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK));
  LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |    0x%04"X16_F"     | (ttl, proto, chksum)\n",
                    IPH_TTL(iphdr),
                    IPH_PROTO(iphdr),
                    ntohs(IPH_CHKSUM(iphdr))));
  LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (src)\n",
                    ip4_addr1_16(&iphdr->src),
                    ip4_addr2_16(&iphdr->src),
                    ip4_addr3_16(&iphdr->src),
                    ip4_addr4_16(&iphdr->src)));
  LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
  LWIP_DEBUGF(IP_DEBUG, ("|  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  |  %3"U16_F"  | (dest)\n",
                    ip4_addr1_16(&iphdr->dest),
                    ip4_addr2_16(&iphdr->dest),
                    ip4_addr3_16(&iphdr->dest),
                    ip4_addr4_16(&iphdr->dest)));
  LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
}
#endif /* IP_DEBUG */