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/**

 * @file

 * AutoIP Automatic LinkLocal IP Configuration

 *

 */

/*

 *

 * Copyright (c) 2007 Dominik Spies <kontakt@dspies.de>

 * 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.

 *

 * Author: Dominik Spies <kontakt@dspies.de>

 *

 * This is a AutoIP implementation for the lwIP TCP/IP stack. It aims to conform

 * with RFC 3927.

 *

 *

 * Please coordinate changes and requests with Dominik Spies

 * <kontakt@dspies.de>

 */

/*******************************************************************************

 * USAGE:

 *

 * define LWIP_AUTOIP 1  in your lwipopts.h

 *

 * If you don't use tcpip.c (so, don't call, you don't call tcpip_init):

 * - First, call autoip_init().

 * - call autoip_tmr() all AUTOIP_TMR_INTERVAL msces,

 *   that should be defined in autoip.h.

 *   I recommend a value of 100. The value must divide 1000 with a remainder almost 0.

 *   Possible values are 1000, 500, 333, 250, 200, 166, 142, 125, 111, 100 ....

 *

 * Without DHCP:

 * - Call autoip_start() after netif_add().

 *

 * With DHCP:

 * - define LWIP_DHCP_AUTOIP_COOP 1 in your lwipopts.h.

 * - Configure your DHCP Client.

 *

 */

#include "lwip/opt.h"

#if LWIP_AUTOIP /* don't build if not configured for use in lwipopts.h */

#include "lwip/mem.h"

#include "lwip/udp.h"

#include "lwip/ip_addr.h"

#include "lwip/netif.h"

#include "lwip/autoip.h"

#include "netif/etharp.h"

#include <stdlib.h>

#include <string.h>

/* 169.254.0.0 */

#define AUTOIP_NET         0xA9FE0000

/* 169.254.1.0 */

#define AUTOIP_RANGE_START (AUTOIP_NET | 0x0100)

/* 169.254.254.255 */

#define AUTOIP_RANGE_END   (AUTOIP_NET | 0xFEFF)

/** Pseudo random macro based on netif informations.

 * You could use "rand()" from the C Library if you define LWIP_AUTOIP_RAND in lwipopts.h */

#ifndef LWIP_AUTOIP_RAND

#define LWIP_AUTOIP_RAND(netif) ( (((u32_t)((netif->hwaddr[5]) & 0xff) << 24) | \

                                   ((u32_t)((netif->hwaddr[3]) & 0xff) << 16) | \

                                   ((u32_t)((netif->hwaddr[2]) & 0xff) << 8) | \

                                   ((u32_t)((netif->hwaddr[4]) & 0xff))) + \

                                   (netif->autoip?netif->autoip->tried_llipaddr:0))

#endif /* LWIP_AUTOIP_RAND */

/**

 * Macro that generates the initial IP address to be tried by AUTOIP.

 * If you want to override this, define it to something else in lwipopts.h.

 */

#ifndef LWIP_AUTOIP_CREATE_SEED_ADDR

#define LWIP_AUTOIP_CREATE_SEED_ADDR(netif) \

  htonl(AUTOIP_RANGE_START + ((u32_t)(((u8_t)(netif->hwaddr[4])) | \

                 ((u32_t)((u8_t)(netif->hwaddr[5]))) << 8)))

#endif /* LWIP_AUTOIP_CREATE_SEED_ADDR */

/* static functions */

static void autoip_handle_arp_conflict(struct netif *netif);

/* creates a pseudo random LL IP-Address for a network interface */

static void autoip_create_addr(struct netif *netif, struct ip_addr *ipaddr);

/* sends an ARP probe */

static err_t autoip_arp_probe(struct netif *netif);

/* sends an ARP announce */

static err_t autoip_arp_announce(struct netif *netif);

/* configure interface for use with current LL IP-Address */

static err_t autoip_bind(struct netif *netif);

/* start sending probes for llipaddr */

static void autoip_start_probing(struct netif *netif);

/**

 * Initialize this module

 */

void

autoip_init(void)

{

  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_init()\n"));

}

/**

 * Handle a IP address conflict after an ARP conflict detection

 */

static void

autoip_handle_arp_conflict(struct netif *netif)

{

  /* Somehow detect if we are defending or retreating */

  unsigned char defend = 1; /* tbd */

  if(defend) {

    if(netif->autoip->lastconflict > 0) {

      /* retreat, there was a conflicting ARP in the last

       * DEFEND_INTERVAL seconds

       */

      LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,

        ("autoip_handle_arp_conflict(): we are defending, but in DEFEND_INTERVAL, retreating\n"));

      /* TODO: close all TCP sessions */

      autoip_start(netif);

    } else {

      LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,

        ("autoip_handle_arp_conflict(): we are defend, send ARP Announce\n"));

      autoip_arp_announce(netif);

      netif->autoip->lastconflict = DEFEND_INTERVAL * AUTOIP_TICKS_PER_SECOND;

    }

  } else {

    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,

      ("autoip_handle_arp_conflict(): we do not defend, retreating\n"));

    /* TODO: close all TCP sessions */

    autoip_start(netif);

  }

}

/**

 * Create an IP-Address out of range 169.254.1.0 to 169.254.254.255

 *

 * @param netif network interface on which create the IP-Address

 * @param ipaddr ip address to initialize

 */

static void

autoip_create_addr(struct netif *netif, struct ip_addr *ipaddr)

{

  /* Here we create an IP-Address out of range 169.254.1.0 to 169.254.254.255

   * compliant to RFC 3927 Section 2.1

   * We have 254 * 256 possibilities */

  u32_t addr = ntohl(LWIP_AUTOIP_CREATE_SEED_ADDR(netif));

  addr += netif->autoip->tried_llipaddr;

  addr = AUTOIP_NET | (addr & 0xffff);

  /* Now, 169.254.0.0 <= addr <= 169.254.255.255 */

  if (addr < AUTOIP_RANGE_START) {

    addr += AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;

  }

  if (addr > AUTOIP_RANGE_END) {

    addr -= AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;

  }

  LWIP_ASSERT("AUTOIP address not in range", (addr >= AUTOIP_RANGE_START) &&

    (addr <= AUTOIP_RANGE_END));

  ipaddr->addr = htonl(addr);

  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,

    ("autoip_create_addr(): tried_llipaddr=%"U16_F", 0x%08"X32_F"\n",

    (u16_t)(netif->autoip->tried_llipaddr), (u32_t)(ipaddr->addr)));

}

/**

 * Sends an ARP probe from a network interface

 *

 * @param netif network interface used to send the probe

 */

static err_t

autoip_arp_probe(struct netif *netif)

{

  return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,

    (struct eth_addr *)netif->hwaddr, IP_ADDR_ANY, &ethzero,

    &netif->autoip->llipaddr, ARP_REQUEST);

}

/**

 * Sends an ARP announce from a network interface

 *

 * @param netif network interface used to send the announce

 */

static err_t

autoip_arp_announce(struct netif *netif)

{

  return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast,

    (struct eth_addr *)netif->hwaddr, &netif->autoip->llipaddr, &ethzero,

    &netif->autoip->llipaddr, ARP_REQUEST);

}

/**

 * Configure interface for use with current LL IP-Address

 *

 * @param netif network interface to configure with current LL IP-Address

 */

static err_t

autoip_bind(struct netif *netif)

{

  struct autoip *autoip = netif->autoip;

  struct ip_addr sn_mask, gw_addr;

  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,

    ("autoip_bind(netif=%p) %c%c%"U16_F" 0x%08"X32_F"\n",

    (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num, autoip->llipaddr.addr));

  IP4_ADDR(&sn_mask, 255, 255, 0, 0);

  IP4_ADDR(&gw_addr, 0, 0, 0, 0);

  netif_set_ipaddr(netif, &autoip->llipaddr);

  netif_set_netmask(netif, &sn_mask);

  netif_set_gw(netif, &gw_addr);

  /* bring the interface up */

  netif_set_up(netif);

  return ERR_OK;

}

/**

 * Start AutoIP client

 *

 * @param netif network interface on which start the AutoIP client

 */

err_t

autoip_start(struct netif *netif)

{

  struct autoip *autoip = netif->autoip;

  err_t result = ERR_OK;

  if(netif_is_up(netif)) {

    netif_set_down(netif);

  }

  /* Set IP-Address, Netmask and Gateway to 0 to make sure that

   * ARP Packets are formed correctly

   */

  netif->ip_addr.addr = 0;

  netif->netmask.addr = 0;

  netif->gw.addr      = 0;

  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,

    ("autoip_start(netif=%p) %c%c%"U16_F"\n", (void*)netif, netif->name[0],

    netif->name[1], (u16_t)netif->num));

  if(autoip == NULL) {

    /* no AutoIP client attached yet? */

    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,

      ("autoip_start(): starting new AUTOIP client\n"));

    autoip = mem_malloc(sizeof(struct autoip));

    if(autoip == NULL) {

      LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,

        ("autoip_start(): could not allocate autoip\n"));

      return ERR_MEM;

    }

    memset( autoip, 0, sizeof(struct autoip));

    /* store this AutoIP client in the netif */

    netif->autoip = autoip;

    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_start(): allocated autoip"));

  } else {

    autoip->state = AUTOIP_STATE_OFF;

    autoip->ttw = 0;

    autoip->sent_num = 0;

    memset(&autoip->llipaddr, 0, sizeof(struct ip_addr));

    autoip->lastconflict = 0;

  }

  autoip_create_addr(netif, &(autoip->llipaddr));

  autoip->tried_llipaddr++;

  autoip_start_probing(netif);

  return result;

}

static void

autoip_start_probing(struct netif *netif)

{

  struct autoip *autoip = netif->autoip;

  autoip->state = AUTOIP_STATE_PROBING;

  autoip->sent_num = 0;

  /* time to wait to first probe, this is randomly

   * choosen out of 0 to PROBE_WAIT seconds.

   * compliant to RFC 3927 Section 2.2.1

   */

  autoip->ttw = (u16_t)(LWIP_AUTOIP_RAND(netif) % (PROBE_WAIT * AUTOIP_TICKS_PER_SECOND));

  /*

   * if we tried more then MAX_CONFLICTS we must limit our rate for

   * accquiring and probing address

   * compliant to RFC 3927 Section 2.2.1

   */

  if(autoip->tried_llipaddr > MAX_CONFLICTS) {

    autoip->ttw = RATE_LIMIT_INTERVAL * AUTOIP_TICKS_PER_SECOND;

  }

}

/**

 * Handle a possible change in the network configuration.

 *

 * If there is an AutoIP address configured, take the interface down

 * and begin probing with the same address.

 */

void

autoip_network_changed(struct netif *netif)

{

  if (netif->autoip && netif->autoip->state != AUTOIP_STATE_OFF) {

    netif_set_down(netif);

    autoip_start_probing(netif);

  }

}

/**

 * Stop AutoIP client

 *

 * @param netif network interface on which stop the AutoIP client

 */

err_t

autoip_stop(struct netif *netif)

{

  netif->autoip->state = AUTOIP_STATE_OFF;

  netif_set_down(netif);

  return ERR_OK;

}

/**

 * Has to be called in loop every AUTOIP_TMR_INTERVAL milliseconds

 */

void

autoip_tmr()

{

  struct netif *netif = netif_list;

  /* loop through netif's */

  while (netif != NULL) {

    /* only act on AutoIP configured interfaces */

    if (netif->autoip != NULL) {

      if(netif->autoip->lastconflict > 0) {

        netif->autoip->lastconflict--;

      }

      LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,

        ("autoip_tmr() AutoIP-State: %"U16_F", ttw=%"U16_F"\n",

        (u16_t)(netif->autoip->state), netif->autoip->ttw));

      switch(netif->autoip->state) {

        case AUTOIP_STATE_PROBING:

          if(netif->autoip->ttw > 0) {

            netif->autoip->ttw--;

          } else {

            if(netif->autoip->sent_num >= PROBE_NUM) {

              netif->autoip->state = AUTOIP_STATE_ANNOUNCING;

              netif->autoip->sent_num = 0;

              netif->autoip->ttw = ANNOUNCE_WAIT * AUTOIP_TICKS_PER_SECOND;

            } else {

              autoip_arp_probe(netif);

              LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,

                ("autoip_tmr() PROBING Sent Probe\n"));

              netif->autoip->sent_num++;

              /* calculate time to wait to next probe */

              netif->autoip->ttw = (u16_t)((LWIP_AUTOIP_RAND(netif) %

                ((PROBE_MAX - PROBE_MIN) * AUTOIP_TICKS_PER_SECOND) ) +

                PROBE_MIN * AUTOIP_TICKS_PER_SECOND);

            }

          }

          break;

        case AUTOIP_STATE_ANNOUNCING:

          if(netif->autoip->ttw > 0) {

            netif->autoip->ttw--;

          } else {

            if(netif->autoip->sent_num == 0) {

             /* We are here the first time, so we waited ANNOUNCE_WAIT seconds

              * Now we can bind to an IP address and use it.

              *

              * autoip_bind calls netif_set_up. This triggers a gratuitous ARP

              * which counts as an announcement.

              */

              autoip_bind(netif);

            } else {

              autoip_arp_announce(netif);

              LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,

                ("autoip_tmr() ANNOUNCING Sent Announce\n"));

            }

            netif->autoip->ttw = ANNOUNCE_INTERVAL * AUTOIP_TICKS_PER_SECOND;

            netif->autoip->sent_num++;

            if(netif->autoip->sent_num >= ANNOUNCE_NUM) {

                netif->autoip->state = AUTOIP_STATE_BOUND;

                netif->autoip->sent_num = 0;

                netif->autoip->ttw = 0;

            }

          }

          break;

      }

    }

    /* proceed to next network interface */

    netif = netif->next;

  }

}

/**

 * Handles every incoming ARP Packet, called by etharp_arp_input.

 *

 * @param netif network interface to use for autoip processing

 * @param hdr Incoming ARP packet

 */

void

autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr)

{

  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_arp_reply()\n"));

  if ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) {

   /* when ip.src == llipaddr && hw.src != netif->hwaddr

    *

    * when probing  ip.dst == llipaddr && hw.src != netif->hwaddr

    * we have a conflict and must solve it

    */

    struct ip_addr sipaddr, dipaddr;

    struct eth_addr netifaddr;

    netifaddr.addr[0] = netif->hwaddr[0];

    netifaddr.addr[1] = netif->hwaddr[1];

    netifaddr.addr[2] = netif->hwaddr[2];

    netifaddr.addr[3] = netif->hwaddr[3];

    netifaddr.addr[4] = netif->hwaddr[4];

    netifaddr.addr[5] = netif->hwaddr[5];

    /* Copy struct ip_addr2 to aligned ip_addr, to support compilers without

     * structure packing (not using structure copy which breaks strict-aliasing rules).

     */

    SMEMCPY(&sipaddr, &hdr->sipaddr, sizeof(sipaddr));

    SMEMCPY(&dipaddr, &hdr->dipaddr, sizeof(dipaddr));

    if ((netif->autoip->state == AUTOIP_STATE_PROBING) ||

        ((netif->autoip->state == AUTOIP_STATE_ANNOUNCING) &&

         (netif->autoip->sent_num == 0))) {

     /* RFC 3927 Section 2.2.1:

      * from beginning to after ANNOUNCE_WAIT

      * seconds we have a conflict if

      * ip.src == llipaddr OR

      * ip.dst == llipaddr && hw.src != own hwaddr

      */

      if ((ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr)) ||

          (ip_addr_cmp(&dipaddr, &netif->autoip->llipaddr) &&

           !eth_addr_cmp(&netifaddr, &hdr->shwaddr))) {

        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING,

          ("autoip_arp_reply(): Probe Conflict detected\n"));

        autoip_start(netif);

      }

    } else {

     /* RFC 3927 Section 2.5:

      * in any state we have a conflict if

      * ip.src == llipaddr && hw.src != own hwaddr

      */

      if (ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr) &&

          !eth_addr_cmp(&netifaddr, &hdr->shwaddr)) {

        LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING,

          ("autoip_arp_reply(): Conflicting ARP-Packet detected\n"));

        autoip_handle_arp_conflict(netif);

      }

    }

  }

}

#endif /* LWIP_AUTOIP */