コード例 #1
0
ファイル: ip.c プロジェクト: Joel397/Ongoing_work_files
/*-----------------------------------------------------------------------------------*/
err_t
ip_input(struct pbuf *p, struct netif *inp) {
    static struct ip_hdr *iphdr;
    static struct netif *netif;
    static u8_t hl;



#ifdef IP_STATS
    ++stats.ip.recv;
#endif /* IP_STATS */

    /* identify the IP header */
    iphdr = p->payload;
    if(IPH_V(iphdr) != 4) {
        DEBUGF(IP_DEBUG, ("IP packet dropped due to bad version number %d\n", IPH_V(iphdr)));
#if IP_DEBUG
        ip_debug_print(p);
#endif /* IP_DEBUG */
        pbuf_free(p);
#ifdef IP_STATS
        ++stats.ip.err;
        ++stats.ip.drop;
#endif /* IP_STATS */
        return ERR_OK;
    }

    hl = IPH_HL(iphdr);

    if(hl * 4 > p->len) {
        DEBUGF(IP_DEBUG, ("IP packet dropped due to too short packet %d\n", p->len));

        pbuf_free(p);
#ifdef IP_STATS
        ++stats.ip.lenerr;
        ++stats.ip.drop;
#endif /* IP_STATS */
        return ERR_OK;
    }

    /* verify checksum */
    if(inet_chksum(iphdr, hl * 4) != 0) {

        DEBUGF(IP_DEBUG, ("IP packet dropped due to failing checksum 0x%x\n", inet_chksum(iphdr, hl * 4)));
#if IP_DEBUG
        ip_debug_print(p);
#endif /* IP_DEBUG */
        pbuf_free(p);
#ifdef IP_STATS
        ++stats.ip.chkerr;
        ++stats.ip.drop;
#endif /* IP_STATS */
        return ERR_OK;
    }

    /* Trim pbuf. This should have been done at the netif layer,
       but we'll do it anyway just to be sure that its done. */
    pbuf_realloc(p, ntohs(IPH_LEN(iphdr)));

    /* is this packet for us? */
    for(netif = netif_list; netif != NULL; netif = netif->next) {

        DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%lx netif->ip_addr 0x%lx (0x%lx, 0x%lx, 0x%lx)\n",
                          iphdr->dest.addr, netif->ip_addr.addr,
                          iphdr->dest.addr & netif->netmask.addr,
                          netif->ip_addr.addr & netif->netmask.addr,
                          iphdr->dest.addr & ~(netif->netmask.addr)));

        if(ip_addr_isany(&(netif->ip_addr)) ||
                ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
                (ip_addr_isbroadcast(&(iphdr->dest), &(netif->netmask)) &&
                 ip_addr_maskcmp(&(iphdr->dest), &(netif->ip_addr), &(netif->netmask))) ||
                ip_addr_cmp(&(iphdr->dest), IP_ADDR_BROADCAST)) {
            break;
        }
    }

#if LWIP_DHCP
    /* If a DHCP packet has arrived on the interface, we pass it up the
       stack regardless of destination IP address. The reason is that
       DHCP replies are sent to the IP adress that will be given to this
       node (as recommended by RFC 1542 section 3.1.1, referred by RFC
       2131). */
    if(IPH_PROTO(iphdr) == IP_PROTO_UDP &&
            ((struct udp_hdr *)((u8_t *)iphdr + IPH_HL(iphdr) * 4/sizeof(u8_t)))->src ==
            DHCP_SERVER_PORT) {
        netif = inp;
    }
#endif /* LWIP_DHCP */

    if(netif == NULL) {
        /* packet not for us, route or discard */
        DEBUGF(IP_DEBUG, ("ip_input: packet not for us.\n"));
#if IP_FORWARD
        if(!ip_addr_isbroadcast(&(iphdr->dest), &(inp->netmask))) {
            ip_forward(p, iphdr, inp);
        }
#endif /* IP_FORWARD */
        pbuf_free(p);
        return ERR_OK;
    }

#if IP_REASSEMBLY
    if((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
        p = ip_reass(p);
        if(p == NULL) {
            return ERR_OK;
        }
        iphdr = p->payload;
    }
#else /* IP_REASSEMBLY */
    if((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
        pbuf_free(p);
        DEBUGF(IP_DEBUG, ("IP packet dropped since it was fragmented (0x%x).\n",
                          ntohs(IPH_OFFSET(iphdr))));
#ifdef IP_STATS
        ++stats.ip.opterr;
        ++stats.ip.drop;
#endif /* IP_STATS */
        return ERR_OK;
    }
#endif /* IP_REASSEMBLY */

#if IP_OPTIONS == 0
    if(hl * 4 > IP_HLEN) {
        DEBUGF(IP_DEBUG, ("IP packet dropped since there were IP options.\n"));

        pbuf_free(p);
#ifdef IP_STATS
        ++stats.ip.opterr;
        ++stats.ip.drop;
#endif /* IP_STATS */
        return ERR_OK;
    }
#endif /* IP_OPTIONS == 0 */


    /* send to upper layers */
#if IP_DEBUG
    DEBUGF(IP_DEBUG, ("ip_input: \n"));
    ip_debug_print(p);
    DEBUGF(IP_DEBUG, ("ip_input: p->len %d p->tot_len %d\n", p->len, p->tot_len));
#endif /* IP_DEBUG */

    switch(IPH_PROTO(iphdr)) {
#if LWIP_UDP > 0
    case IP_PROTO_UDP:
        udp_input(p, inp);
        break;
#endif /* LWIP_UDP */
#if LWIP_TCP > 0
    case IP_PROTO_TCP:
        tcp_input(p, inp);
        break;
#endif /* LWIP_TCP */
    case IP_PROTO_ICMP:
        icmp_input(p, inp);
        break;
    default:
        /* send ICMP destination protocol unreachable unless is was a broadcast */
        if(!ip_addr_isbroadcast(&(iphdr->dest), &(inp->netmask)) &&
                !ip_addr_ismulticast(&(iphdr->dest))) {
            p->payload = iphdr;
            icmp_dest_unreach(p, ICMP_DUR_PROTO);
        }
        pbuf_free(p);

        DEBUGF(IP_DEBUG, ("Unsupported transportation protocol %d\n", IPH_PROTO(iphdr)));

#ifdef IP_STATS
        ++stats.ip.proterr;
        ++stats.ip.drop;
#endif /* IP_STATS */

    }
    return ERR_OK;
}
コード例 #2
0
ファイル: raw.c プロジェクト: Montanari9/Ethernet_Echoclient
/**
 * Determine if in incoming IP packet is covered by a RAW PCB
 * and if so, pass it to a user-provided receive callback function.
 *
 * Given an incoming IP datagram (as a chain of pbufs) this function
 * finds a corresponding RAW PCB and calls the corresponding receive
 * callback function.
 *
 * @param p pbuf to be demultiplexed to a RAW PCB.
 * @param inp network interface on which the datagram was received.
 * @return - 1 if the packet has been eaten by a RAW PCB receive
 *           callback function. The caller MAY NOT not reference the
 *           packet any longer, and MAY NOT call pbuf_free().
 * @return - 0 if packet is not eaten (pbuf is still referenced by the
 *           caller).
 *
 */
u8_t
raw_input(struct pbuf *p, struct netif *inp)
{
  struct raw_pcb *pcb, *prev;
  s16_t proto;
  u8_t eaten = 0;

  LWIP_UNUSED_ARG(inp);

#if LWIP_IPV6
#if LWIP_IPV4
  if (IP_HDR_GET_VERSION(p->payload) == 6)
#endif /* LWIP_IPV4 */
  {
    struct ip6_hdr *ip6hdr = (struct ip6_hdr *)p->payload;
    proto = IP6H_NEXTH(ip6hdr);
  }
#if LWIP_IPV4
  else
#endif /* LWIP_IPV4 */
#endif /* LWIP_IPV6 */
#if LWIP_IPV4
  {
    proto = IPH_PROTO((struct ip_hdr *)p->payload);
  }
#endif /* LWIP_IPV4 */

  prev = NULL;
  pcb = raw_pcbs;
  /* loop through all raw pcbs until the packet is eaten by one */
  /* this allows multiple pcbs to match against the packet by design */
  while ((eaten == 0) && (pcb != NULL)) {
    if ((pcb->protocol == proto) && IP_PCB_IPVER_INPUT_MATCH(pcb) &&
        (ip_addr_isany(&pcb->local_ip) ||
         ip_addr_cmp(&pcb->local_ip, ip_current_dest_addr()))) {
#if IP_SOF_BROADCAST_RECV
      /* broadcast filter? */
      if ((ip_get_option(pcb, SOF_BROADCAST) || !ip_addr_isbroadcast(ip_current_dest_addr(), ip_current_netif()))
          || PCB_ISIPV6(pcb)
          )
#endif /* IP_SOF_BROADCAST_RECV */
      {
        /* receive callback function available? */
        if (pcb->recv != NULL) {
#ifndef LWIP_NOASSERT
          void* old_payload = p->payload;
#endif
          /* the receive callback function did not eat the packet? */
          eaten = pcb->recv(pcb->recv_arg, pcb, p, ip_current_src_addr());
          if (eaten != 0) {
            /* receive function ate the packet */
            p = NULL;
            eaten = 1;
            if (prev != NULL) {
            /* move the pcb to the front of raw_pcbs so that is
               found faster next time */
              prev->next = pcb->next;
              pcb->next = raw_pcbs;
              raw_pcbs = pcb;
            }
          } else {
            /* sanity-check that the receive callback did not alter the pbuf */
            LWIP_ASSERT("raw pcb recv callback altered pbuf payload pointer without eating packet",
              p->payload == old_payload);
          }
        }
        /* no receive callback function was set for this raw PCB */
      }
      /* drop the packet */
    }
    prev = pcb;
    pcb = pcb->next;
  }
  return eaten;
}
コード例 #3
0
/*-----------------------------------------------------------------------------------*/
void
tcpdump(struct pbuf *p)
{
  struct ip_hdr *iphdr;
  struct tcp_hdr *tcphdr;
#if LWIP_UDP
  struct udp_hdr *udphdr;
#endif
  char flags[5];
  int i;
  int len;
  int offset;

  if (file == NULL) {
    return;
  }
#ifdef IPv4
  iphdr = (struct ip_hdr *)p->payload;
  switch (IPH_PROTO(iphdr)) {
#if LWIP_TCP
  case IP_PROTO_TCP:
    tcphdr = (struct tcp_hdr *)((char *)iphdr + IP_HLEN);

    pbuf_header(p, -IP_HLEN);
    if (inet_chksum_pseudo(p, (ip_addr_t *)&(iphdr->src),
			  (ip_addr_t *)&(iphdr->dest),
			  IP_PROTO_TCP, p->tot_len) != 0) {
      LWIP_DEBUGF(TCPDUMP_DEBUG, ("tcpdump: IP checksum failed!\n"));
      /*    fprintf(file, "chksum 0x%lx ", tcphdr->chksum);
	    tcphdr->chksum = 0;
	    fprintf(file, "should be 0x%lx ", inet_chksum_pseudo(p, (ip_addr_t *)&(iphdr->src),
	    (ip_addr_t *)&(iphdr->dest),
	    IP_PROTO_TCP, p->tot_len));*/
      fprintf(file, "!chksum ");
    }

    i = 0;
    if (TCPH_FLAGS(tcphdr) & TCP_SYN) {
      flags[i++] = 'S';
    }
    if (TCPH_FLAGS(tcphdr) & TCP_PSH) {
      flags[i++] = 'P';
    }
    if (TCPH_FLAGS(tcphdr) & TCP_FIN) {
      flags[i++] = 'F';
    }
    if (TCPH_FLAGS(tcphdr) & TCP_RST) {
      flags[i++] = 'R';
    }
    if (i == 0) {
      flags[i++] = '.';
    }
    flags[i++] = 0;



    fprintf(file, "%d.%d.%d.%d.%u > %d.%d.%d.%d.%u: ",
	    (int)(ntohl(iphdr->src.addr) >> 24) & 0xff,
	    (int)(ntohl(iphdr->src.addr) >> 16) & 0xff,
	    (int)(ntohl(iphdr->src.addr) >> 8) & 0xff,
	    (int)(ntohl(iphdr->src.addr) >> 0) & 0xff,
	    ntohs(tcphdr->src),
	  (int)(ntohl(iphdr->dest.addr) >> 24) & 0xff,
	    (int)(ntohl(iphdr->dest.addr) >> 16) & 0xff,
	    (int)(ntohl(iphdr->dest.addr) >> 8) & 0xff,
	    (int)(ntohl(iphdr->dest.addr) >> 0) & 0xff,
	    ntohs(tcphdr->dest));
    offset = TCPH_HDRLEN(tcphdr);

    len = ntohs(IPH_LEN(iphdr)) - offset * 4 - IP_HLEN;
    if (len != 0 || flags[0] != '.') {
      fprintf(file, "%s %u:%u(%u) ",
	      flags,
	      ntohl(tcphdr->seqno),
	      ntohl(tcphdr->seqno) + len,
	      len);
    }
    if (TCPH_FLAGS(tcphdr) & TCP_ACK) {
      fprintf(file, "ack %u ",
	      ntohl(tcphdr->ackno));
    }
    fprintf(file, "wnd %u\n",
	    ntohs(tcphdr->wnd));

    fflush(file);

    pbuf_header(p, IP_HLEN);
    break;
#endif /* LWIP_TCP */

#if LWIP_UDP
  case IP_PROTO_UDP:
    udphdr = (struct udp_hdr *)((char *)iphdr + IP_HLEN);

    pbuf_header(p, -IP_HLEN);
    if (inet_chksum_pseudo(p, (ip_addr_t *)&(iphdr->src),
			  (ip_addr_t *)&(iphdr->dest),
			  IP_PROTO_UDP, p->tot_len) != 0) {
      LWIP_DEBUGF(TCPDUMP_DEBUG, ("tcpdump: IP checksum failed!\n"));
      /*    fprintf(file, "chksum 0x%lx ", tcphdr->chksum);
	    tcphdr->chksum = 0;
	    fprintf(file, "should be 0x%lx ", inet_chksum_pseudo(p, (ip_addr_t *)&(iphdr->src),
	    (ip_addr_t *)&(iphdr->dest),
	    IP_PROTO_TCP, p->tot_len));*/
      fprintf(file, "!chksum ");
    }

    fprintf(file, "%d.%d.%d.%d.%u > %d.%d.%d.%d.%u: ",
	    (int)(ntohl(iphdr->src.addr) >> 24) & 0xff,
	    (int)(ntohl(iphdr->src.addr) >> 16) & 0xff,
	    (int)(ntohl(iphdr->src.addr) >> 8) & 0xff,
	    (int)(ntohl(iphdr->src.addr) >> 0) & 0xff,
	    ntohs(udphdr->src),
	  (int)(ntohl(iphdr->dest.addr) >> 24) & 0xff,
	    (int)(ntohl(iphdr->dest.addr) >> 16) & 0xff,
	    (int)(ntohl(iphdr->dest.addr) >> 8) & 0xff,
	    (int)(ntohl(iphdr->dest.addr) >> 0) & 0xff,
	    ntohs(udphdr->dest));
    fprintf(file, "U ");
    len = ntohs(IPH_LEN(iphdr)) - sizeof(struct udp_hdr) - IP_HLEN;
    fprintf(file, " %d\n", len);

    fflush(file);

    pbuf_header(p, IP_HLEN);
    break;
#endif /* LWIP_UDP */
  default:
    LWIP_DEBUGF(TCPDUMP_DEBUG, ("unhandled IP protocol: %d\n", (int)IPH_PROTO(iphdr)));
    break;

  }
#endif /* IPv4 */
}
コード例 #4
0
/**
 * Process an incoming UDP datagram.
 *
 * Given an incoming UDP datagram (as a chain of pbufs) this function
 * finds a corresponding UDP PCB and hands over the pbuf to the pcbs
 * recv function. If no pcb is found or the datagram is incorrect, the
 * pbuf is freed.
 *
 * @param p pbuf to be demultiplexed to a UDP PCB.
 * @param inp network interface on which the datagram was received.
 *
 */
void
udp_input(struct pbuf *p, struct netif *inp)
{
  struct udp_hdr *udphdr;
  struct udp_pcb *pcb, *prev;
  struct udp_pcb *uncon_pcb;
  struct ip_hdr *iphdr;
  u16_t src, dest;
  u8_t local_match;
  u8_t broadcast;

  PERF_START;

  UDP_STATS_INC(udp.recv);

  iphdr = (struct ip_hdr *)p->payload;

  /* Check minimum length (IP header + UDP header)
   * and move payload pointer to UDP header */
  if (p->tot_len < (IPH_HL(iphdr) * 4 + UDP_HLEN) || pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4))) {
    /* drop short packets */
    LWIP_DEBUGF(UDP_DEBUG,
                ("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
    UDP_STATS_INC(udp.lenerr);
    UDP_STATS_INC(udp.drop);
    snmp_inc_udpinerrors();
    pbuf_free(p);
    goto end;
  }

  udphdr = (struct udp_hdr *)p->payload;

  /* is broadcast packet ? */
  broadcast = ip_addr_isbroadcast(&current_iphdr_dest, inp);

  LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));

  /* convert src and dest ports to host byte order */
  src = ntohs(udphdr->src);
  dest = ntohs(udphdr->dest);

  udp_debug_print(udphdr);

  /* print the UDP source and destination */
  LWIP_DEBUGF(UDP_DEBUG,
              ("udp (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") <-- "
               "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
               ip4_addr1_16(&iphdr->dest), ip4_addr2_16(&iphdr->dest),
               ip4_addr3_16(&iphdr->dest), ip4_addr4_16(&iphdr->dest), ntohs(udphdr->dest),
               ip4_addr1_16(&iphdr->src), ip4_addr2_16(&iphdr->src),
               ip4_addr3_16(&iphdr->src), ip4_addr4_16(&iphdr->src), ntohs(udphdr->src)));

#if LWIP_DHCP
  pcb = NULL;
  /* when LWIP_DHCP is active, packets to DHCP_CLIENT_PORT may only be processed by
     the dhcp module, no other UDP pcb may use the local UDP port DHCP_CLIENT_PORT */
  if (dest == DHCP_CLIENT_PORT) {
    /* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
    if (src == DHCP_SERVER_PORT) {
      if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
        /* accept the packe if 
           (- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
           - inp->dhcp->pcb->remote == ANY or iphdr->src */
        if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
           ip_addr_cmp(&(inp->dhcp->pcb->remote_ip), &current_iphdr_src))) {
          pcb = inp->dhcp->pcb;
        }
      }
    }
  } else
#endif /* LWIP_DHCP */
  {
    prev = NULL;
    local_match = 0;
    uncon_pcb = NULL;
    /* Iterate through the UDP pcb list for a matching pcb.
     * 'Perfect match' pcbs (connected to the remote port & ip address) are
     * preferred. If no perfect match is found, the first unconnected pcb that
     * matches the local port and ip address gets the datagram. */
    for (pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
      local_match = 0;
      /* print the PCB local and remote address */
      LWIP_DEBUGF(UDP_DEBUG,
                  ("pcb (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") --- "
                   "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
                   ip4_addr1_16(&pcb->local_ip), ip4_addr2_16(&pcb->local_ip),
                   ip4_addr3_16(&pcb->local_ip), ip4_addr4_16(&pcb->local_ip), pcb->local_port,
                   ip4_addr1_16(&pcb->remote_ip), ip4_addr2_16(&pcb->remote_ip),
                   ip4_addr3_16(&pcb->remote_ip), ip4_addr4_16(&pcb->remote_ip), pcb->remote_port));

      /* compare PCB local addr+port to UDP destination addr+port */
      if (pcb->local_port == dest) {
        if (
           (!broadcast && ip_addr_isany(&pcb->local_ip)) ||
           ip_addr_cmp(&(pcb->local_ip), &current_iphdr_dest) ||
#if LWIP_IGMP
           ip_addr_ismulticast(&current_iphdr_dest) ||
#endif /* LWIP_IGMP */
#if IP_SOF_BROADCAST_RECV
            (broadcast && ip_get_option(pcb, SOF_BROADCAST) &&
             (ip_addr_isany(&pcb->local_ip) ||
              ip_addr_netcmp(&pcb->local_ip, ip_current_dest_addr(), &inp->netmask)))) {
#else /* IP_SOF_BROADCAST_RECV */
            (broadcast &&
             (ip_addr_isany(&pcb->local_ip) ||
              ip_addr_netcmp(&pcb->local_ip, ip_current_dest_addr(), &inp->netmask)))) {
#endif /* IP_SOF_BROADCAST_RECV */ 
          local_match = 1;
          if ((uncon_pcb == NULL) && 
              ((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
            /* the first unconnected matching PCB */
            uncon_pcb = pcb;
          }
        }
      }
      /* compare PCB remote addr+port to UDP source addr+port */
      if ((local_match != 0) &&
          (pcb->remote_port == src) &&
          (ip_addr_isany(&pcb->remote_ip) ||
           ip_addr_cmp(&(pcb->remote_ip), &current_iphdr_src))) {
        /* the first fully matching PCB */
        if (prev != NULL) {
          /* move the pcb to the front of udp_pcbs so that is
             found faster next time */
          prev->next = pcb->next;
          pcb->next = udp_pcbs;
          udp_pcbs = pcb;
        } else {
          UDP_STATS_INC(udp.cachehit);
        }
        break;
      }
      prev = pcb;
    }
    /* no fully matching pcb found? then look for an unconnected pcb */
    if (pcb == NULL) {
      pcb = uncon_pcb;
    }
  }

  /* Check checksum if this is a match or if it was directed at us. */
  if (pcb != NULL || ip_addr_cmp(&inp->ip_addr, &current_iphdr_dest)) {
    LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
#if LWIP_UDPLITE
    if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
      /* Do the UDP Lite checksum */
#if CHECKSUM_CHECK_UDP
      u16_t chklen = ntohs(udphdr->len);
      if (chklen < sizeof(struct udp_hdr)) {
        if (chklen == 0) {
          /* For UDP-Lite, checksum length of 0 means checksum
             over the complete packet (See RFC 3828 chap. 3.1) */
          chklen = p->tot_len;
        } else {
          /* At least the UDP-Lite header must be covered by the
             checksum! (Again, see RFC 3828 chap. 3.1) */
          UDP_STATS_INC(udp.chkerr);
          UDP_STATS_INC(udp.drop);
          snmp_inc_udpinerrors();
          pbuf_free(p);
          goto end;
        }
      }
      if (inet_chksum_pseudo_partial(p, &current_iphdr_src, &current_iphdr_dest,
                             IP_PROTO_UDPLITE, p->tot_len, chklen) != 0) {
       LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
                   ("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
        UDP_STATS_INC(udp.chkerr);
        UDP_STATS_INC(udp.drop);
        snmp_inc_udpinerrors();
        pbuf_free(p);
        goto end;
      }
#endif /* CHECKSUM_CHECK_UDP */
    } else
#endif /* LWIP_UDPLITE */
    {
#if CHECKSUM_CHECK_UDP
      if (udphdr->chksum != 0) {
        if (inet_chksum_pseudo(p, ip_current_src_addr(), ip_current_dest_addr(),
                               IP_PROTO_UDP, p->tot_len) != 0) {
          LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_LEVEL_SERIOUS,
                      ("udp_input: UDP datagram discarded due to failing checksum\n"));
          UDP_STATS_INC(udp.chkerr);
          UDP_STATS_INC(udp.drop);
          snmp_inc_udpinerrors();
          pbuf_free(p);
          goto end;
        }
      }
#endif /* CHECKSUM_CHECK_UDP */
    }
    if(pbuf_header(p, -UDP_HLEN)) {
      /* Can we cope with this failing? Just assert for now */
      LWIP_ASSERT("pbuf_header failed\n", 0);
      UDP_STATS_INC(udp.drop);
      snmp_inc_udpinerrors();
      pbuf_free(p);
      goto end;
    }
    if (pcb != NULL) {
      snmp_inc_udpindatagrams();
#if SO_REUSE && SO_REUSE_RXTOALL
      if ((broadcast || ip_addr_ismulticast(&current_iphdr_dest)) &&
          ip_get_option(pcb, SOF_REUSEADDR)) {
        /* pass broadcast- or multicast packets to all multicast pcbs
           if SOF_REUSEADDR is set on the first match */
        struct udp_pcb *mpcb;
        u8_t p_header_changed = 0;
        for (mpcb = udp_pcbs; mpcb != NULL; mpcb = mpcb->next) {
          if (mpcb != pcb) {
            /* compare PCB local addr+port to UDP destination addr+port */
            if ((mpcb->local_port == dest) &&
                ((!broadcast && ip_addr_isany(&mpcb->local_ip)) ||
                 ip_addr_cmp(&(mpcb->local_ip), &current_iphdr_dest) ||
#if LWIP_IGMP
                 ip_addr_ismulticast(&current_iphdr_dest) ||
#endif /* LWIP_IGMP */
#if IP_SOF_BROADCAST_RECV
                 (broadcast && ip_get_option(mpcb, SOF_BROADCAST)))) {
#else  /* IP_SOF_BROADCAST_RECV */
                 (broadcast))) {
#endif /* IP_SOF_BROADCAST_RECV */
              /* pass a copy of the packet to all local matches */
              if (mpcb->recv != NULL) {
                struct pbuf *q;
                /* for that, move payload to IP header again */
                if (p_header_changed == 0) {
                  pbuf_header(p, (s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
                  p_header_changed = 1;
                }
                q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
                if (q != NULL) {
                  err_t err = pbuf_copy(q, p);
                  if (err == ERR_OK) {
                    /* move payload to UDP data */
                    pbuf_header(q, -(s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
                    mpcb->recv(mpcb->recv_arg, mpcb, q, ip_current_src_addr(), src);
                  }
                }
              }
            }
          }
        }
        if (p_header_changed) {
          /* and move payload to UDP data again */
          pbuf_header(p, -(s16_t)((IPH_HL(iphdr) * 4) + UDP_HLEN));
        }
      }
#endif /* SO_REUSE && SO_REUSE_RXTOALL */
      /* callback */
      if (pcb->recv != NULL) {
        /* now the recv function is responsible for freeing p */
        pcb->recv(pcb->recv_arg, pcb, p, ip_current_src_addr(), src);
      } else {
        /* no recv function registered? then we have to free the pbuf! */
        pbuf_free(p);
        goto end;
      }
    } else {
コード例 #5
0
ファイル: udp.c プロジェクト: CharlieBashford/P33
/*-----------------------------------------------------------------------------------*/
void
udp_input(struct pbuf *p, struct netif *inp)
{
  struct udp_hdr *udphdr;  
  struct udp_pcb *pcb;
  struct ip_hdr *iphdr;
  uint16_t src, dest;
  
  
#ifdef UDP_STATS
  ++stats.udp.recv;
#endif /* UDP_STATS */

  iphdr = p->payload;

  pbuf_header(p, -(UDP_HLEN + IPH_HL(iphdr) * 4));

  udphdr = (struct udp_hdr *)((uint8_t *)p->payload - UDP_HLEN);
  
  DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %d\n", p->tot_len));
	
  src = NTOHS(udphdr->src);
  dest = NTOHS(udphdr->dest);

#if UDP_DEBUG
  udp_debug_print(udphdr);
#endif /* UDP_DEBUG */
  
  /* Demultiplex packet. First, go for a perfect match. */
  for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
    DEBUGF(UDP_DEBUG, ("udp_input: pcb local port %d (dgram %d)\n",
		       pcb->local_port, ntohs(udphdr->dest)));
    if(pcb->remote_port == src &&
       pcb->local_port == dest &&
       (ip_addr_isany(&pcb->remote_ip) ||
	ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src))) &&
       (ip_addr_isany(&pcb->local_ip) ||
	ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
      break;
    }
  }

  if(pcb == NULL) {
    for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
      DEBUGF(UDP_DEBUG, ("udp_input: pcb local port %d (dgram %d)\n",
			 pcb->local_port, dest));
      if(pcb->local_port == dest &&
	 (ip_addr_isany(&pcb->remote_ip) ||
	  ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src))) &&
	 (ip_addr_isany(&pcb->local_ip) ||
	  ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)))) {
	break;
      }      
    }
  }


  /* Check checksum if this is a match or if it was directed at us. */
  /*  if(pcb != NULL ||
      ip_addr_cmp(&inp->ip_addr, &iphdr->dest)) {*/
  if(pcb != NULL) {
    DEBUGF(UDP_DEBUG, ("udp_input: calculating checksum\n"));
    pbuf_header(p, UDP_HLEN);    
#ifdef IPv6
    if(iphdr->nexthdr == IP_PROTO_UDPLITE) {    
#else
    if(IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {    
#endif /* IPv4 */
      /* Do the UDP Lite checksum */
      if(inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
			    (struct ip_addr *)&(iphdr->dest),
			    IP_PROTO_UDPLITE, ntohs(udphdr->len)) != 0) {
	DEBUGF(UDP_DEBUG, ("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
#ifdef UDP_STATS
	++stats.udp.chkerr;
	++stats.udp.drop;
#endif /* UDP_STATS */
	pbuf_free(p);
	goto end;
      }
    } else {
      if(udphdr->chksum != 0) {
	if(inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
			      (struct ip_addr *)&(iphdr->dest),
			      IP_PROTO_UDP, p->tot_len) != 0) {
	  DEBUGF(UDP_DEBUG, ("udp_input: UDP datagram discarded due to failing checksum\n"));
	  
#ifdef UDP_STATS
	  ++stats.udp.chkerr;
	  ++stats.udp.drop;
#endif /* UDP_STATS */
	  pbuf_free(p);
	  goto end;
	}
      }
    }
    pbuf_header(p, -UDP_HLEN);    
    if(pcb != NULL) {
      pcb->recv(pcb->recv_arg, pcb, p, &(iphdr->src), src);
    } else {
      DEBUGF(UDP_DEBUG, ("udp_input: not for us.\n"));
      
      /* No match was found, send ICMP destination port unreachable unless
	 destination address was broadcast/multicast. */
      
      if(!ip_addr_isbroadcast(&iphdr->dest, &inp->netmask) &&
	 !ip_addr_ismulticast(&iphdr->dest)) {
	
	/* deconvert from host to network byte order */
	udphdr->src = htons(udphdr->src);
	udphdr->dest = htons(udphdr->dest); 
	
	/* adjust pbuf pointer */
	p->payload = iphdr;
	icmp_dest_unreach(p, ICMP_DUR_PORT);
      }
#ifdef UDP_STATS
      ++stats.udp.proterr;
      ++stats.udp.drop;
#endif /* UDP_STATS */
      pbuf_free(p);
    }
  } else {
    pbuf_free(p);
  }

  end:
	while(0); /* hack to remove compiler warning */
	
}
/*-----------------------------------------------------------------------------------*/
err_t
udp_send(struct udp_pcb *pcb, struct pbuf *p)
{
  struct udp_hdr *udphdr;
  struct ip_addr *src_ip;
  err_t err;
  struct pbuf *q;
  
  if(pbuf_header(p, UDP_HLEN)) {
    q = pbuf_alloc(PBUF_IP, UDP_HLEN, PBUF_RAM);
    if(q == NULL) {
      return ERR_MEM;
    }
    pbuf_chain(q, p);
    p = q;
  }

  udphdr = p->payload;
  udphdr->src = htons(pcb->local_port);
  udphdr->dest = htons(pcb->remote_port);
  udphdr->chksum = 0x0000;

  src_ip = &(pcb->local_ip);
  
  DEBUGF(UDP_DEBUG, ("udp_send: sending datagram of length %d\n", p->tot_len));
  
  if(pcb->flags & UDP_FLAGS_UDPLITE) {
    udphdr->len = htons(pcb->chksum_len);
    /* calculate checksum */
    udphdr->chksum = inet_chksum_pseudo(p, src_ip, &(pcb->remote_ip),
					IP_PROTO_UDP, pcb->chksum_len);
    if(udphdr->chksum == 0x0000) {
      udphdr->chksum = 0xffff;
    }
    err = sr_lwip_output(p, &pcb->local_ip, &pcb->remote_ip, IP_PROTO_UDPLITE);
  } else {
    udphdr->len = htons(p->tot_len);
    /* calculate checksum */
    if((pcb->flags & UDP_FLAGS_NOCHKSUM) == 0) {
      udphdr->chksum = inet_chksum_pseudo(p, src_ip, &pcb->remote_ip,
					  IP_PROTO_UDP, p->tot_len);
      if(udphdr->chksum == 0x0000) {
	udphdr->chksum = 0xffff;
      }
    }
    err = sr_lwip_output(p,&pcb->local_ip, &pcb->remote_ip, IP_PROTO_UDP);
  }
  
#ifdef UDP_STATS
  ++stats.udp.xmit;
#endif /* UDP_STATS */
  return err;
}
/*-----------------------------------------------------------------------------------*/
err_t
udp_bind(struct udp_pcb *pcb, struct ip_addr *ipaddr, uint16_t port)
{
  struct udp_pcb *ipcb;
  ip_addr_set(&pcb->local_ip, ipaddr);
  pcb->local_port = port;

  /* Insert UDP PCB into the list of active UDP PCBs. */
  for(ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
    if(pcb == ipcb) {
      /* Already on the list, just return. */
      return ERR_OK;
    }
  }
  /* We need to place the PCB on the list. */
  pcb->next = udp_pcbs;
  udp_pcbs = pcb;

  DEBUGF(UDP_DEBUG, ("udp_bind: bound to port %d\n", port));
  return ERR_OK;
}
/*-----------------------------------------------------------------------------------*/
err_t
udp_connect(struct udp_pcb *pcb, struct ip_addr *ipaddr, uint16_t port)
{
  struct udp_pcb *ipcb;
  ip_addr_set(&pcb->remote_ip, ipaddr);
  pcb->remote_port = port;

  /* Insert UDP PCB into the list of active UDP PCBs. */
  for(ipcb = udp_pcbs; ipcb != NULL; ipcb = ipcb->next) {
    if(pcb == ipcb) {
      /* Already on the list, just return. */
      return ERR_OK;
    }
  }
  /* We need to place the PCB on the list. */
  pcb->next = udp_pcbs;
  udp_pcbs = pcb;
  return ERR_OK;
}
/*-----------------------------------------------------------------------------------*/
void
udp_recv(struct udp_pcb *pcb,
	 void (* recv)(void *arg, struct udp_pcb *upcb, struct pbuf *p,
		       struct ip_addr *addr, uint16_t port),
	 void *recv_arg)
{
  pcb->recv = recv;
  pcb->recv_arg = recv_arg;
}
コード例 #6
0
ファイル: ip.c プロジェクト: ChenZewei/DualOSCCF
/**
 * This function is called by the network interface device driver when
 * an IP packet is received. The function does the basic checks of the
 * IP header such as packet size being at least larger than the header
 * size etc. If the packet was not destined for us, the packet is
 * forwarded (using ip_forward). The IP checksum is always checked.
 *
 * Finally, the packet is sent to the upper layer protocol input function.
 * 
 * @param p the received IP packet (p->payload points to IP header)
 * @param inp the netif on which this packet was received
 * @return ERR_OK if the packet was processed (could return ERR_* if it wasn't
 *         processed, but currently always returns ERR_OK)
 */
err_t
ip_input(struct pbuf *p, struct netif *inp)
{
  //static int mytmptest;
  struct ip_hdr *iphdr;
  struct netif *netif;
  u16_t iphdr_hlen;
  u16_t iphdr_len;
#if LWIP_DHCP
  int check_ip_src=1;
#endif /* LWIP_DHCP */

  IP_STATS_INC(ip.recv);
  snmp_inc_ipinreceives();

  /* identify the IP header */
  iphdr = p->payload;
  if (IPH_V(iphdr) != 4) {
    LWIP_DEBUGF(IP_DEBUG | 1, ("IP packet dropped due to bad version number %"U16_F"\n", IPH_V(iphdr)));
    ip_debug_print(p);
    pbuf_free(p);
    IP_STATS_INC(ip.err);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipinhdrerrors();
    return ERR_OK;
  }

  /* obtain IP header length in number of 32-bit words */
  iphdr_hlen = IPH_HL(iphdr);
  /* calculate IP header length in bytes */
  iphdr_hlen *= 4;
  /* obtain ip length in bytes */
  iphdr_len = ntohs(IPH_LEN(iphdr));

  /* header length exceeds first pbuf length, or ip length exceeds total pbuf length? */
  if ((iphdr_hlen > p->len) || (iphdr_len > p->tot_len)) {
    if (iphdr_hlen > p->len)
    LWIP_DEBUGF(IP_DEBUG | 2, ("IP header (len %"U16_F") does not fit in first pbuf (len %"U16_F"), IP packet dropped.\n",
                               iphdr_hlen, p->len));
    if (iphdr_len > p->tot_len)
    LWIP_DEBUGF(IP_DEBUG | 2, ("IP (len %"U16_F") is longer than pbuf (len %"U16_F"), "
                               "IP packet dropped.\n",
                               iphdr_len, p->tot_len));
    /* free (drop) packet pbufs */
    pbuf_free(p);
    IP_STATS_INC(ip.lenerr);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipindiscards();
    return ERR_OK;
  }

  /* verify checksum */
#if CHECKSUM_CHECK_IP
  if (inet_chksum(iphdr, iphdr_hlen) != 0) {

    LWIP_DEBUGF(IP_DEBUG | 2, ("Checksum (0x%"X16_F") failed, IP packet dropped.\n", inet_chksum(iphdr, iphdr_hlen)));
    ip_debug_print(p);
    pbuf_free(p);
    IP_STATS_INC(ip.chkerr);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipinhdrerrors();
    return ERR_OK;
  }
#endif

  /* Trim pbuf. This should have been done at the netif layer,
   * but we'll do it anyway just to be sure that its done. */
  pbuf_realloc(p, iphdr_len);

  /* match packet against an interface, i.e. is this packet for us? */
#if LWIP_IGMP
  if (ip_addr_ismulticast(&(iphdr->dest))) {
    if ((inp->flags & NETIF_FLAG_IGMP) && (igmp_lookfor_group(inp, &(iphdr->dest)))) {
      netif = inp;
    } else {
      netif = NULL;
    }
  } else
#endif /* LWIP_IGMP */
  {
    /* start trying with inp. if that's not acceptable, start walking the
       list of configured netifs.
       'first' is used as a boolean to mark whether we started walking the list */
    int first = 1;
    netif = inp;
    do {
      LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%"X32_F" netif->ip_addr 0x%"X32_F" (0x%"X32_F", 0x%"X32_F", 0x%"X32_F")\n",
          iphdr->dest.addr, netif->ip_addr.addr,
          iphdr->dest.addr & netif->netmask.addr,
          netif->ip_addr.addr & netif->netmask.addr,
          iphdr->dest.addr & ~(netif->netmask.addr)));

      /* interface is up and configured? */
      if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr)))) {
        /* unicast to this interface address? */
        if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
            /* or broadcast on this interface network address? */
            ip_addr_isbroadcast(&(iphdr->dest), netif)) {
          LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
              netif->name[0], netif->name[1]));
          /* break out of for loop */
          break;
        }
      }
      if (first) {
        first = 0;
        netif = netif_list;
      } else {
        netif = netif->next;
      }
      if (netif == inp) {
        netif = netif->next;
      }
    } while(netif != NULL);
  }

#if LWIP_DHCP
  /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
   * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
   * According to RFC 1542 section 3.1.1, referred by RFC 2131).
   */
  if (netif == NULL) {
    /* remote port is DHCP server? */
    if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
      LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: UDP packet to DHCP client port %"U16_F"\n",
        ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen))->dest)));
      if (ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdr_hlen))->dest) == DHCP_CLIENT_PORT) {
        LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: DHCP packet accepted.\n"));
        netif = inp;
        check_ip_src = 0;
      }
    }
  }
#endif /* LWIP_DHCP */

  /* broadcast or multicast packet source address? Compliant with RFC 1122: 3.2.1.3 */
#if LWIP_DHCP
  if (check_ip_src)
#endif /* LWIP_DHCP */
  {  if ((ip_addr_isbroadcast(&(iphdr->src), inp)) ||
         (ip_addr_ismulticast(&(iphdr->src)))) {
      /* packet source is not valid */
      LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: packet source is not valid.\n"));
      /* free (drop) packet pbufs */
      pbuf_free(p);
      IP_STATS_INC(ip.drop);
      snmp_inc_ipinaddrerrors();
      snmp_inc_ipindiscards();
      return ERR_OK;
    }
  }

  /* packet not for us? */
  if (netif == NULL) {
    /* packet not for us, route or discard */
    LWIP_DEBUGF(IP_DEBUG | LWIP_DBG_TRACE | 1, ("ip_input: packet not for us.\n"));
#if IP_FORWARD
    /* non-broadcast packet? */
    if (!ip_addr_isbroadcast(&(iphdr->dest), inp)) {
      /* try to forward IP packet on (other) interfaces */
      ip_forward(p, iphdr, inp);
    } else
#endif /* IP_FORWARD */
    {
      snmp_inc_ipinaddrerrors();
      snmp_inc_ipindiscards();
    }
    pbuf_free(p);
    return ERR_OK;
  }
  /* packet consists of multiple fragments? */
  if ((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
#if IP_REASSEMBLY /* packet fragment reassembly code present? */
    LWIP_DEBUGF(IP_DEBUG, ("IP packet is a fragment (id=0x%04"X16_F" tot_len=%"U16_F" len=%"U16_F" MF=%"U16_F" offset=%"U16_F"), calling ip_reass()\n",
      ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & htons(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
    /* reassemble the packet*/
    p = ip_reass(p);
    /* packet not fully reassembled yet? */
    if (p == NULL) {
      return ERR_OK;
    }
    iphdr = p->payload;
#else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
    pbuf_free(p);
    LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since it was fragmented (0x%"X16_F") (while IP_REASSEMBLY == 0).\n",
      ntohs(IPH_OFFSET(iphdr))));
    IP_STATS_INC(ip.opterr);
    IP_STATS_INC(ip.drop);
    /* unsupported protocol feature */
    snmp_inc_ipinunknownprotos();
    return ERR_OK;
#endif /* IP_REASSEMBLY */
  }

#if IP_OPTIONS_ALLOWED == 0 /* no support for IP options in the IP header? */

#if LWIP_IGMP
  /* there is an extra "router alert" option in IGMP messages which we allow for but do not police */
  if((iphdr_hlen > IP_HLEN &&  (IPH_PROTO(iphdr) != IP_PROTO_IGMP)) {
#else
  if (iphdr_hlen > IP_HLEN) {
#endif /* LWIP_IGMP */
    LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS_ALLOWED == 0).\n"));
    pbuf_free(p);
    IP_STATS_INC(ip.opterr);
    IP_STATS_INC(ip.drop);
    /* unsupported protocol feature */
    snmp_inc_ipinunknownprotos();
    return ERR_OK;
  }
#endif /* IP_OPTIONS_ALLOWED == 0 */

  /* send to upper layers */
  
  //acoral_print("\n ip_input.=== %d\n", mytmptest++);
  //acoral_prints("\r\n===ip_input===\r\n");
  
  LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
  ip_debug_print(p);
  LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %"U16_F" p->tot_len %"U16_F"\n", p->len, p->tot_len));

#if LWIP_RAW
  /* raw input did not eat the packet? */
  if (raw_input(p, inp) == 0)
#endif /* LWIP_RAW */
  {
    //acoral_print("\nip proto: %d\n",ntohs((iphdr)->_ttl_proto) & 0xff);
    switch (IPH_PROTO(iphdr)) {
#if LWIP_UDP
    case IP_PROTO_UDP:
#if LWIP_UDPLIT
fE
    case IP_PROTO_UDPLITE:
#endif /* LWIP_UDPLITE */
      snmp_inc_ipindelivers();
      //acoral_prints("\nUDP\n");
      udp_input(p, inp);
      break;
#endif /* LWIP_UDP */
#if LWIP_TCP
    case IP_PROTO_TCP:
      snmp_inc_ipindelivers();
      //acoral_print("\nTCP: tot_len:%d, type:%d\n", p->tot_len, p->type);
      tcp_input(p, inp);
      //acoral_print("\ni am here.=== %d\n", mytmptest++);
      //pbuf_free(p);
      break;
#endif /* LWIP_TCP */
#if LWIP_ICMP
    case IP_PROTO_ICMP:
      snmp_inc_ipindelivers();
      //acoral_prints("\nICMPS\n");
      icmp_input(p, inp);
      //acoral_prints("\nICMPE\n");
      break;
#endif /* LWIP_ICMP */
#if LWIP_IGMP
    case IP_PROTO_IGMP:
      igmp_input(p,inp,&(iphdr->dest));
      break;
#endif /* LWIP_IGMP */
    default:
#if LWIP_ICMP
      /* send ICMP destination protocol unreachable unless is was a broadcast */
      if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
          !ip_addr_ismulticast(&(iphdr->dest))) {
        p->payload = iphdr;
        icmp_dest_unreach(p, ICMP_DUR_PROTO);
      }
#endif /* LWIP_ICMP */
      pbuf_free(p);

      LWIP_DEBUGF(IP_DEBUG | 2, ("Unsupported transport protocol %"U16_F"\n", IPH_PROTO(iphdr)));

      IP_STATS_INC(ip.proterr);
      IP_STATS_INC(ip.drop);
      snmp_inc_ipinunknownprotos();
    }
    
  }
  //acoral_print("\n===  input ok  ===\n");
  return ERR_OK;
}

/**
 * Sends an IP packet on a network interface. This function constructs
 * the IP header and calculates the IP header checksum. If the source
 * IP address is NULL, the IP address of the outgoing network
 * interface is filled in as source address.
 * If the destination IP address is IP_HDRINCL, p is assumed to already
 * include an IP header and p->payload points to it instead of the data.
 *
 * @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 netif the netif on which to send this packet
 * @return ERR_OK if the packet was sent OK
 *         ERR_BUF if p doesn't have enough space for IP/LINK headers
 *         returns errors returned by netif->output
 *
 * @note ip_id: RFC791 "some host may be able to simply use
 *  unique identifiers independent of destination"
 */
err_t
ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
             u8_t ttl, u8_t tos,
             u8_t proto, struct netif *netif)
{
  struct ip_hdr *iphdr;
  static u16_t ip_id = 0;

  snmp_inc_ipoutrequests();

  /* Should the IP header be generated or is it already included in p? */
  if (dest != IP_HDRINCL) {
    /* generate IP header */
    if (pbuf_header(p, IP_HLEN)) {
      LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: not enough room for IP header in pbuf\n"));

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

    iphdr = 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);

    ip_addr_set(&(iphdr->dest), dest);

    IPH_VHLTOS_SET(iphdr, 4, IP_HLEN / 4, tos);
    IPH_LEN_SET(iphdr, htons(p->tot_len));
    IPH_OFFSET_SET(iphdr, 0);
    IPH_ID_SET(iphdr, htons(ip_id));
    ++ip_id;

    if (ip_addr_isany(src)) {
      ip_addr_set(&(iphdr->src), &(netif->ip_addr));
    } else {
      ip_addr_set(&(iphdr->src), src);
    }

    IPH_CHKSUM_SET(iphdr, 0);
#if CHECKSUM_GEN_IP
    IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
#endif
  } else {
    /* IP header already included in p */
    iphdr = p->payload;
    dest = &(iphdr->dest);
  }

#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_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);

  LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
  //acoral_print("\r\nIpOutPutIf***netif\r\n");
  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, struct ip_addr *src, struct ip_addr *dest,
          u8_t ttl, u8_t tos, u8_t proto)
{
  struct netif *netif;

  if ((netif = ip_route(dest)) == NULL) {
    return ERR_RTE;
  }
  //acoral_print("\r\nIP_OUTPUT\r\n");
  return ip_output_if(p, src, dest, ttl, tos, proto, netif);
}

#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 = 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(&iphdr->src),
                    ip4_addr2(&iphdr->src),
                    ip4_addr3(&iphdr->src),
                    ip4_addr4(&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(&iphdr->dest),
                    ip4_addr2(&iphdr->dest),
                    ip4_addr3(&iphdr->dest),
                    ip4_addr4(&iphdr->dest)));
  LWIP_DEBUGF(IP_DEBUG, ("+-------------------------------+\n"));
}
コード例 #7
0
err_t
ip_input(struct pbuf *p, struct netif *inp) {
  struct ip_hdr *iphdr;
  struct netif *netif;
  u16_t iphdrlen;

  IP_STATS_INC(ip.recv);
  snmp_inc_ipinreceives();

  /* identify the IP header */
  iphdr = p->payload;
  if (IPH_V(iphdr) != 4) {
    LWIP_DEBUGF(IP_DEBUG | 1, ("IP packet dropped due to bad version number %u\n", IPH_V(iphdr)));
    ip_debug_print(p);
    pbuf_free(p);
    IP_STATS_INC(ip.err);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipunknownprotos();
    return ERR_OK;
  }
  /* obtain IP header length in number of 32-bit words */
  iphdrlen = IPH_HL(iphdr);
  /* calculate IP header length in bytes */
  iphdrlen *= 4;

  /* header length exceeds first pbuf length? */
  if (iphdrlen > p->len) {
    LWIP_DEBUGF(IP_DEBUG | 2, ("IP header (len %u) does not fit in first pbuf (len %u), IP packet droppped.\n",
      iphdrlen, p->len));
    /* free (drop) packet pbufs */
    pbuf_free(p);
    IP_STATS_INC(ip.lenerr);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipindiscards();
    return ERR_OK;
  }

  /* verify checksum */
#if CHECKSUM_CHECK_IP
  if (inet_chksum(iphdr, iphdrlen) != 0) {

    LWIP_DEBUGF(IP_DEBUG | 2, ("Checksum (0x%x) failed, IP packet dropped.\n", inet_chksum(iphdr, iphdrlen)));
    ip_debug_print(p);
    pbuf_free(p);
    IP_STATS_INC(ip.chkerr);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipindiscards();
    return ERR_OK;
  }
#endif

  /* Trim pbuf. This should have been done at the netif layer,
   * but we'll do it anyway just to be sure that its done. */
  pbuf_realloc(p, ntohs(IPH_LEN(iphdr)));

  /* match packet against an interface, i.e. is this packet for us? */
  for (netif = netif_list; netif != NULL; netif = netif->next) {

    LWIP_DEBUGF(IP_DEBUG, ("ip_input: iphdr->dest 0x%lx netif->ip_addr 0x%lx (0x%lx, 0x%lx, 0x%lx)\n",
      iphdr->dest.addr, netif->ip_addr.addr,
      iphdr->dest.addr & netif->netmask.addr,
      netif->ip_addr.addr & netif->netmask.addr,
      iphdr->dest.addr & ~(netif->netmask.addr)));

    /* interface is up and configured? */
    if ((netif_is_up(netif)) && (!ip_addr_isany(&(netif->ip_addr))))
    {
      /* unicast to this interface address? */
      if (ip_addr_cmp(&(iphdr->dest), &(netif->ip_addr)) ||
         /* or broadcast on this interface network address? */
         ip_addr_isbroadcast(&(iphdr->dest), netif)) {
        LWIP_DEBUGF(IP_DEBUG, ("ip_input: packet accepted on interface %c%c\n",
          netif->name[0], netif->name[1]));
        /* break out of for loop */
        break;
      }
    }
  }
#if LWIP_DHCP
  /* Pass DHCP messages regardless of destination address. DHCP traffic is addressed
   * using link layer addressing (such as Ethernet MAC) so we must not filter on IP.
   * According to RFC 1542 section 3.1.1, referred by RFC 2131).
   */
  if (netif == NULL) {
    /* remote port is DHCP server? */
    if (IPH_PROTO(iphdr) == IP_PROTO_UDP) {
      LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: UDP packet to DHCP client port %u\n",
        ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdrlen))->dest)));
      if (ntohs(((struct udp_hdr *)((u8_t *)iphdr + iphdrlen))->dest) == DHCP_CLIENT_PORT) {
        LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: DHCP packet accepted.\n"));
        netif = inp;
      }
    }
  }
#endif /* LWIP_DHCP */
  /* packet not for us? */
  if (netif == NULL) {
    /* packet not for us, route or discard */
    LWIP_DEBUGF(IP_DEBUG | DBG_TRACE | 1, ("ip_input: packet not for us.\n"));
#if IP_FORWARD
    /* non-broadcast packet? */
    if (!ip_addr_isbroadcast(&(iphdr->dest), inp)) {
      /* try to forward IP packet on (other) interfaces */
      ip_forward(p, iphdr, inp);
    }
    else
#endif /* IP_FORWARD */
    {
      snmp_inc_ipindiscards();
    }
    pbuf_free(p);
    return ERR_OK;
  }
  /* packet consists of multiple fragments? */
  if ((IPH_OFFSET(iphdr) & htons(IP_OFFMASK | IP_MF)) != 0) {
#if IP_REASSEMBLY /* packet fragment reassembly code present? */
    LWIP_DEBUGF(IP_DEBUG, ("IP packet is a fragment (id=0x%04x tot_len=%u len=%u MF=%u offset=%u), calling ip_reass()\n",
      ntohs(IPH_ID(iphdr)), p->tot_len, ntohs(IPH_LEN(iphdr)), !!(IPH_OFFSET(iphdr) & htons(IP_MF)), (ntohs(IPH_OFFSET(iphdr)) & IP_OFFMASK)*8));
    /* reassemble the packet*/
    p = ip_reass(p);
    /* packet not fully reassembled yet? */
    if (p == NULL) {
      return ERR_OK;
    }
    iphdr = p->payload;
#else /* IP_REASSEMBLY == 0, no packet fragment reassembly code present */
    pbuf_free(p);
    LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since it was fragmented (0x%x) (while IP_REASSEMBLY == 0).\n",
      ntohs(IPH_OFFSET(iphdr))));
    IP_STATS_INC(ip.opterr);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipunknownprotos();
    return ERR_OK;
#endif /* IP_REASSEMBLY */
  }

#if IP_OPTIONS == 0 /* no support for IP options in the IP header? */
  if (iphdrlen > IP_HLEN) {
    LWIP_DEBUGF(IP_DEBUG | 2, ("IP packet dropped since there were IP options (while IP_OPTIONS == 0).\n"));
    pbuf_free(p);
    IP_STATS_INC(ip.opterr);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipunknownprotos();
    return ERR_OK;
  }
#endif /* IP_OPTIONS == 0 */

  /* send to upper layers */
  LWIP_DEBUGF(IP_DEBUG, ("ip_input: \n"));
  ip_debug_print(p);
  LWIP_DEBUGF(IP_DEBUG, ("ip_input: p->len %d p->tot_len %d\n", p->len, p->tot_len));

#if LWIP_RAW
  /* raw input did not eat the packet? */
  if (raw_input(p, inp) == 0) {
#endif /* LWIP_RAW */

  switch (IPH_PROTO(iphdr)) {
#if LWIP_UDP
  case IP_PROTO_UDP:
  case IP_PROTO_UDPLITE:
    snmp_inc_ipindelivers();
    udp_input(p, inp);
    break;
#endif /* LWIP_UDP */
#if LWIP_TCP
  case IP_PROTO_TCP:
    snmp_inc_ipindelivers();
    tcp_input(p, inp);
    break;
#endif /* LWIP_TCP */
  case IP_PROTO_ICMP:
    snmp_inc_ipindelivers();
    icmp_input(p, inp);
    break;
  default:
    /* send ICMP destination protocol unreachable unless is was a broadcast */
    if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
        !ip_addr_ismulticast(&(iphdr->dest))) {
      p->payload = iphdr;
      icmp_dest_unreach(p, ICMP_DUR_PROTO);
    }
    pbuf_free(p);

    LWIP_DEBUGF(IP_DEBUG | 2, ("Unsupported transport protocol %d\n", IPH_PROTO(iphdr)));

    IP_STATS_INC(ip.proterr);
    IP_STATS_INC(ip.drop);
    snmp_inc_ipunknownprotos();
  }
#if LWIP_RAW
  } /* LWIP_RAW */
#endif
  return ERR_OK;
}
/**
 * Resolve and fill-in Ethernet address header for outgoing packet.
 *
 * If ARP has the Ethernet address in cache, the given packet is
 * returned, ready to be sent.
 *
 * If ARP does not have the Ethernet address in cache the packet is
 * queued (if enabled and space available) and a ARP request is sent.
 * This ARP request is returned as a pbuf, which should be sent by
 * the caller.
 *
 * A returned non-NULL packet should be sent by the caller.
 *
 * If ARP failed to allocate resources, NULL is returned.
 *
 * @param netif The lwIP network interface which the IP packet will be sent on.
 * @param ipaddr The IP address of the packet destination.
 * @param pbuf The pbuf(s) containing the IP packet to be sent.
 *
 * @return If non-NULL, a packet ready to be sent by caller.
 *
 * @return
 * - ERR_BUF Could not make room for Ethernet header.
 * - ERR_MEM Hardware address unknown, and no more ARP entries available
 *   to query for address or queue the packet.
 * - ERR_RTE No route to destination (no gateway to external networks).
 */
err_t
etharp_output(struct netif *netif, struct ip_addr *ipaddr, struct pbuf *q)
{
  struct eth_addr *dest, *srcaddr, mcastaddr;
  struct eth_hdr *ethhdr;
  err_t result = ERR_OK;
  struct ip_hdr *iphdr;  //615wu
	
  iphdr = q->payload;	//615wu	
	
  /* make room for Ethernet header - should not fail */
  if (pbuf_header(q, sizeof(struct eth_hdr)) != 0) {
    /* bail out */
    LWIP_DEBUGF(ETHARP_DEBUG | DBG_TRACE | 2, ("etharp_output: could not allocate room for header.\n"));
    LINK_STATS_INC(link.lenerr);
    return ERR_BUF;
  }

  /* assume unresolved Ethernet address */
  dest = NULL;
  /* Determine on destination hardware address. Broadcasts and multicasts
   * are special, other IP addresses are looked up in the ARP table. */
	
  /* destination IP address is an IP broadcast address? */
  if (ip_addr_isany(ipaddr) || ip_addr_isbroadcast(ipaddr, netif)) {
    /* broadcast on Ethernet also */
    dest = (struct eth_addr *)&ethbroadcast;
  /* destination IP address is an IP multicast address? */
  } else if (ip_addr_ismulticast(ipaddr)) {
    /* Hash IP multicast address to MAC address. */
    mcastaddr.addr[0] = 0x01;
    mcastaddr.addr[1] = 0x00;
    mcastaddr.addr[2] = 0x5e;
    mcastaddr.addr[3] = ip4_addr2(ipaddr) & 0x7f;
    mcastaddr.addr[4] = ip4_addr3(ipaddr);
    mcastaddr.addr[5] = ip4_addr4(ipaddr);
    /* destination Ethernet address is multicast */
    dest = &mcastaddr;
  /* destination IP address is an IP unicast address */
  } else {
    /* outside local network? */
    if (!ip_addr_maskcmp(ipaddr, &(netif->ip_addr), &(netif->netmask))  
#if 0	//ZOT716u2
#ifdef O_AXIS 
      /* Open TCP/IP layer hole */
        &&  ( !TCP_HOLE_FLAG || ( IPH_PROTO(iphdr) == IP_PROTO_UDP ) )//615wu 
#endif//O_AXIS      
#endif	//ZOT716u2  
#ifdef RENDEZVOUS
		&&  (!mRENVEnable || ( !ip_addr_ismulticast(&(iphdr->dest)) && !is_linklocal((iphdr->dest))) )
#endif//RENDEZVOUS
      ) {
      /* interface has default gateway? */
      if (netif->gw.addr != 0) {
        /* send to hardware address of default gateway IP address */
        ipaddr = &(netif->gw);
      /* no default gateway available */
      } else {
        /* no route to destination error */
        return ERR_RTE;
      }
    }
    /* queue on destination Ethernet address belonging to ipaddr */
    return etharp_query(netif, ipaddr, q);
  }

  /* destination Ethernet address known */
  if (dest != NULL) {
    u8_t i;
    /* obtain source Ethernet address of the given interface */
    srcaddr = (struct eth_addr *)netif->hwaddr;
    /* A valid IP->MAC address mapping was found, fill in the
     * Ethernet header for the outgoing packet */
    ethhdr = q->payload;
    for (i = 0; i < netif->hwaddr_len; i++) {
      ethhdr->dest.addr[i] = dest->addr[i];
      ethhdr->src.addr[i] = srcaddr->addr[i];
    }
    ethhdr->type = htons(ETHTYPE_IP);
    /* send packet */
    result = netif->linkoutput(netif, q);
  }
  return result;
}
コード例 #9
0
ファイル: udp.c プロジェクト: WWU-TSS/people-counter
/**
 * Process an incoming UDP datagram.
 *
 * Given an incoming UDP datagram (as a chain of pbufs) this function
 * finds a corresponding UDP PCB and hands over the pbuf to the pcbs
 * recv function. If no pcb is found or the datagram is incorrect, the
 * pbuf is freed.
 *
 * @param p pbuf to be demultiplexed to a UDP PCB.
 * @param inp network interface on which the datagram was received.
 *
 */
void
udp_input(struct pbuf *p, struct netif *inp)
{
  struct udp_hdr *udphdr;
  struct udp_pcb *pcb, *prev;
  struct udp_pcb *uncon_pcb;
  struct ip_hdr *iphdr;
  u16_t src, dest;
  u8_t local_match;

  PERF_START;

  UDP_STATS_INC(udp.recv);

  iphdr = (struct ip_hdr *)(p->payload);

  /* Check minimum length (IP header + UDP header)
   * and move payload pointer to UDP header */
  if (p->tot_len < (IPH_HL(iphdr) * 4 + UDP_HLEN) || pbuf_header(p, -(s16_t)(IPH_HL(iphdr) * 4))) {
    /* drop short packets */
    LWIP_DEBUGF(UDP_DEBUG,
                ("udp_input: short UDP datagram (%"U16_F" bytes) discarded\n", p->tot_len));
    UDP_STATS_INC(udp.lenerr);
    UDP_STATS_INC(udp.drop);
    snmp_inc_udpinerrors();
    pbuf_free(p);
    goto end;
  }

  udphdr = (struct udp_hdr *)p->payload;

  LWIP_DEBUGF(UDP_DEBUG, ("udp_input: received datagram of length %"U16_F"\n", p->tot_len));

  /* convert src and dest ports to host byte order */
  src = ntohs(udphdr->src);
  dest = ntohs(udphdr->dest);

  udp_debug_print(udphdr);

  /* print the UDP source and destination */
  LWIP_DEBUGF(UDP_DEBUG,
              ("udp (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") <-- "
               "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
               ip4_addr1(&iphdr->dest), ip4_addr2(&iphdr->dest),
               ip4_addr3(&iphdr->dest), ip4_addr4(&iphdr->dest), ntohs(udphdr->dest),
               ip4_addr1(&iphdr->src), ip4_addr2(&iphdr->src),
               ip4_addr3(&iphdr->src), ip4_addr4(&iphdr->src), ntohs(udphdr->src)));

#if LWIP_DHCP
  pcb = NULL;
  /* when LWIP_DHCP is active, packets to DHCP_CLIENT_PORT may only be processed by
     the dhcp module, no other UDP pcb may use the local UDP port DHCP_CLIENT_PORT */
  if (dest == DHCP_CLIENT_PORT) {
    /* all packets for DHCP_CLIENT_PORT not coming from DHCP_SERVER_PORT are dropped! */
    if (src == DHCP_SERVER_PORT) {
      if ((inp->dhcp != NULL) && (inp->dhcp->pcb != NULL)) {
        /* accept the packe if 
           (- broadcast or directed to us) -> DHCP is link-layer-addressed, local ip is always ANY!
           - inp->dhcp->pcb->remote == ANY or iphdr->src */
        if ((ip_addr_isany(&inp->dhcp->pcb->remote_ip) ||
           ip_addr_cmp(&(inp->dhcp->pcb->remote_ip), &(iphdr->src)))) {
          pcb = inp->dhcp->pcb;
        }
      }
    }
  } else
#endif /* LWIP_DHCP */
  {
    prev = NULL;
    local_match = 0;
    uncon_pcb = NULL;
    /* Iterate through the UDP pcb list for a matching pcb.
     * 'Perfect match' pcbs (connected to the remote port & ip address) are
     * preferred. If no perfect match is found, the first unconnected pcb that
     * matches the local port and ip address gets the datagram. */
    for (pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
      local_match = 0;
      /* print the PCB local and remote address */
      LWIP_DEBUGF(UDP_DEBUG,
                  ("pcb (%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F") --- "
                   "(%"U16_F".%"U16_F".%"U16_F".%"U16_F", %"U16_F")\n",
                   ip4_addr1(&pcb->local_ip), ip4_addr2(&pcb->local_ip),
                   ip4_addr3(&pcb->local_ip), ip4_addr4(&pcb->local_ip), pcb->local_port,
                   ip4_addr1(&pcb->remote_ip), ip4_addr2(&pcb->remote_ip),
                   ip4_addr3(&pcb->remote_ip), ip4_addr4(&pcb->remote_ip), pcb->remote_port));

      /* compare PCB local addr+port to UDP destination addr+port */
      if ((pcb->local_port == dest) &&
          (ip_addr_isany(&pcb->local_ip) ||
           ip_addr_cmp(&(pcb->local_ip), &(iphdr->dest)) || 
#if LWIP_IGMP
           ip_addr_ismulticast(&(iphdr->dest)) ||
#endif /* LWIP_IGMP */
           ip_addr_isbroadcast(&(iphdr->dest), inp))) {
        local_match = 1;
        if ((uncon_pcb == NULL) && 
            ((pcb->flags & UDP_FLAGS_CONNECTED) == 0)) {
          /* the first unconnected matching PCB */     
          uncon_pcb = pcb;
        }
      }
      /* compare PCB remote addr+port to UDP source addr+port */
      if ((local_match != 0) &&
          (pcb->remote_port == src) &&
          (ip_addr_isany(&pcb->remote_ip) ||
           ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)))) {
        /* the first fully matching PCB */
        if (prev != NULL) {
          /* move the pcb to the front of udp_pcbs so that is
             found faster next time */
          prev->next = pcb->next;
          pcb->next = udp_pcbs;
          udp_pcbs = pcb;
        } else {
          UDP_STATS_INC(udp.cachehit);
        }
        break;
      }
      prev = pcb;
    }
    /* no fully matching pcb found? then look for an unconnected pcb */
    if (pcb == NULL) {
      pcb = uncon_pcb;
    }
  }

  /* Check checksum if this is a match or if it was directed at us. */
  if (pcb != NULL || ip_addr_cmp(&inp->ip_addr, &iphdr->dest)) {
    LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: calculating checksum\n"));
#if LWIP_UDPLITE
    if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
      /* Do the UDP Lite checksum */
#if CHECKSUM_CHECK_UDP
      u16_t chklen = ntohs(udphdr->len);
      if (chklen < sizeof(struct udp_hdr)) {
        if (chklen == 0) {
          /* For UDP-Lite, checksum length of 0 means checksum
             over the complete packet (See RFC 3828 chap. 3.1) */
          chklen = p->tot_len;
        } else {
          /* At least the UDP-Lite header must be covered by the
             checksum! (Again, see RFC 3828 chap. 3.1) */
          UDP_STATS_INC(udp.chkerr);
          UDP_STATS_INC(udp.drop);
          snmp_inc_udpinerrors();
          pbuf_free(p);
          goto end;
        }
      }
      if (inet_chksum_pseudo_partial(p, (struct ip_addr *)&(iphdr->src),
                             (struct ip_addr *)&(iphdr->dest),
                             IP_PROTO_UDPLITE, p->tot_len, chklen) != 0) {
        LWIP_DEBUGF(UDP_DEBUG | 2,
                    ("udp_input: UDP Lite datagram discarded due to failing checksum\n"));
        UDP_STATS_INC(udp.chkerr);
        UDP_STATS_INC(udp.drop);
        snmp_inc_udpinerrors();
        pbuf_free(p);
        goto end;
      }
#endif /* CHECKSUM_CHECK_UDP */
    } else
#endif /* LWIP_UDPLITE */
    {
#if CHECKSUM_CHECK_UDP
      if (udphdr->chksum != 0) {
        if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
                               (struct ip_addr *)&(iphdr->dest),
                               IP_PROTO_UDP, p->tot_len) != 0) {
          LWIP_DEBUGF(UDP_DEBUG | 2,
                      ("udp_input: UDP datagram discarded due to failing checksum\n"));
          UDP_STATS_INC(udp.chkerr);
          UDP_STATS_INC(udp.drop);
          snmp_inc_udpinerrors();
          pbuf_free(p);
          goto end;
        }
      }
#endif /* CHECKSUM_CHECK_UDP */
    }
    if(pbuf_header(p, -UDP_HLEN)) {
      /* Can we cope with this failing? Just assert for now */
      LWIP_ASSERT("pbuf_header failed\n", 0);
      UDP_STATS_INC(udp.drop);
      snmp_inc_udpinerrors();
      pbuf_free(p);
      goto end;
    }
    if (pcb != NULL) {
      snmp_inc_udpindatagrams();
      /* callback */
      if (pcb->recv != NULL) {
        /* now the recv function is responsible for freeing p */
        struct ip_addr iphdrsrc;                                                  // __packed hack
        iphdrsrc.addr = iphdr->src.addr;
        pcb->recv(pcb->recv_arg, pcb, p, &iphdrsrc, src);
      } else {
        /* no recv function registered? then we have to free the pbuf! */
        pbuf_free(p);
        goto end;
      }
    } else {
      LWIP_DEBUGF(UDP_DEBUG | LWIP_DBG_TRACE, ("udp_input: not for us.\n"));

#if LWIP_ICMP
      /* No match was found, send ICMP destination port unreachable unless
         destination address was broadcast/multicast. */
      if (!ip_addr_isbroadcast(&(iphdr->dest), inp) &&
          !ip_addr_ismulticast(&iphdr->dest)) {
        /* move payload pointer back to ip header */
        pbuf_header(p, (IPH_HL(iphdr) * 4) + UDP_HLEN);
        LWIP_ASSERT("p->payload == iphdr", (p->payload == iphdr));
        icmp_dest_unreach(p, ICMP_DUR_PORT);
      }
#endif /* LWIP_ICMP */
      UDP_STATS_INC(udp.proterr);
      UDP_STATS_INC(udp.drop);
      snmp_inc_udpnoports();
      pbuf_free(p);
    }
  } else {
    pbuf_free(p);
  }
end:
  PERF_STOP("udp_input");
}