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/* @file

 *

 * This is the IP layer implementation for incoming and outgoing IP traffic.

 *

 * @see ip_frag.c

 *

 */

/*

 * 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>

 *

 */

#include "lwip/opt.h"

#include "lwip/def.h"

#include "lwip/mem.h"

#include "lwip/ip.h"

#include "lwip/ip_frag.h"

#include "lwip/inet.h"

#include "lwip/netif.h"

#include "lwip/icmp.h"

#include "lwip/raw.h"

#include "lwip/udp.h"

#include "lwip/tcp.h"

#include "lwip/stats.h"

#include "arch/perf.h"

#include "lwip/snmp.h"

#if LWIP_DHCP

#  include "lwip/dhcp.h"

#endif /* LWIP_DHCP */

/**

 * Initializes the IP layer.

 */

void

ip_init(void)

{

#if IP_FRAG

  ip_frag_init();

#endif

}

/**

 * Finds the appropriate network interface for a given IP address. It

 * searches the list of network interfaces linearly. A match is found

 * if the masked IP address of the network interface equals the masked

 * IP address given to the function.

 */

struct netif *

ip_route(struct ip_addr *dest)

{

  struct netif *netif;

  /* iterate through netifs */

  for(netif = netif_list; netif != NULL; netif = netif->next) {

    /* network mask matches? */

    if (ip_addr_netcmp(dest, &(netif->ip_addr), &(netif->netmask))) {

      /* return netif on which to forward IP packet */

      return netif;

    }

  }

  /* no matching netif found, use default netif */

  return netif_default;

}

#if IP_FORWARD

/**

 * Forwards an IP packet. It finds an appropriate route for the

 * packet, decrements the TTL value of the packet, adjusts the

 * checksum and outputs the packet on the appropriate interface.

 */

static struct netif *

ip_forward(struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)

{

  struct netif *netif;

  PERF_START;

  /* Find network interface where to forward this IP packet to. */

  netif = ip_route((struct ip_addr *)&(iphdr->dest));

  if (netif == NULL) {

    LWIP_DEBUGF(IP_DEBUG, ("ip_forward: no forwarding route for 0x%"X32_F" found\n",

                      iphdr->dest.addr));

    snmp_inc_ipoutnoroutes();

    return (struct netif *)NULL;

  }

  /* Do not forward packets onto the same network interface on which

   * they arrived. */

  if (netif == inp) {

    LWIP_DEBUGF(IP_DEBUG, ("ip_forward: not bouncing packets back on incoming interface.\n"));

    snmp_inc_ipoutnoroutes();

    return (struct netif *)NULL;

  }

  /* decrement TTL */

  IPH_TTL_SET(iphdr, IPH_TTL(iphdr) - 1);

  /* send ICMP if TTL == 0 */

  if (IPH_TTL(iphdr) == 0) {

    snmp_inc_ipinhdrerrors();

    /* Don't send ICMP messages in response to ICMP messages */

    if (IPH_PROTO(iphdr) != IP_PROTO_ICMP) {

      icmp_time_exceeded(p, ICMP_TE_TTL);

    }

    return (struct netif *)NULL;

  }

  /* Incrementally update the IP checksum. */

  if (IPH_CHKSUM(iphdr) >= htons(0xffff - 0x100)) {

    IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100) + 1);

  } else {

    IPH_CHKSUM_SET(iphdr, IPH_CHKSUM(iphdr) + htons(0x100));

  }

  LWIP_DEBUGF(IP_DEBUG, ("ip_forward: forwarding packet to 0x%"X32_F"\n",

                    iphdr->dest.addr));

  IP_STATS_INC(ip.fw);

  IP_STATS_INC(ip.xmit);

  snmp_inc_ipforwdatagrams();

  PERF_STOP("ip_forward");

  /* transmit pbuf on chosen interface */

  netif->output(netif, p, (struct ip_addr *)&(iphdr->dest));

  return netif;

}

#endif /* IP_FORWARD */

/**

 * 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.

 *

 *

 *

 */

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 %"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 */

  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 %"U16_F") does not fit in first pbuf (len %"U16_F"), 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%"X16_F") 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_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, 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%"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 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 %"U16_F"\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_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 == 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);

    /* unsupported protocol feature */

    snmp_inc_ipinunknownprotos();

    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 %"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 */

  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 %"U16_F"\n", IPH_PROTO(iphdr)));

    IP_STATS_INC(ip.proterr);

    IP_STATS_INC(ip.drop);

    snmp_inc_ipinunknownprotos();

  }

#if LWIP_RAW

  } /* LWIP_RAW */

#endif

  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.

 *

 * @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();

  if (dest != IP_HDRINCL) {

    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;

    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, htons(IP_DF));

    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 {

    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()"));

  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.

 */

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) {

    LWIP_DEBUGF(IP_DEBUG | 2, ("ip_output: No route to 0x%"X32_F"\n", dest->addr));

    IP_STATS_INC(ip.rterr);

    snmp_inc_ipoutnoroutes();

    return ERR_RTE;

  }

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

}

#if IP_DEBUG

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"));

}

#endif /* IP_DEBUG */