autoip.c

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/*
 *
 * 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>
 */
 
#include "net/opt.h"
 
#if LWIP_IPV4 && LWIP_AUTOIP /* don't build if not configured for use in lwipopts.h */
 
#include "net/mem.h"
/* #include "net/udp.h" */
#include "net/ip_addr.h"
#include "net/netif.h"
#include "net/autoip.h"
#include "net/etharp.h"
#include "net/prot/autoip.h"
 
#include <string.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_data(netif)? netif_autoip_data(netif)->tried_llipaddr : 0))
#endif /* LWIP_AUTOIP_RAND */
 
#ifndef LWIP_AUTOIP_CREATE_SEED_ADDR
#define LWIP_AUTOIP_CREATE_SEED_ADDR(netif) \
  lwip_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 err_t autoip_arp_announce(struct netif *netif);
static void autoip_start_probing(struct netif *netif);
 
void
autoip_set_struct(struct netif *netif, struct autoip *autoip)
{
  LWIP_ASSERT("netif != NULL", netif != NULL);
  LWIP_ASSERT("autoip != NULL", autoip != NULL);
  LWIP_ASSERT("netif already has a struct autoip set",
              netif_autoip_data(netif) == NULL);
 
  /* clear data structure */
  memset(autoip, 0, sizeof(struct autoip));
  /* autoip->state = AUTOIP_STATE_OFF; */
  netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_AUTOIP, autoip);
}
 
static void
autoip_restart(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
  autoip->tried_llipaddr++;
  autoip_start(netif);
}
 
static void
autoip_handle_arp_conflict(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
 
  /* RFC3927, 2.5 "Conflict Detection and Defense" allows two options where
     a) means retreat on the first conflict and
     b) allows to keep an already configured address when having only one
        conflict in 10 seconds
     We use option b) since it helps to improve the chance that one of the two
     conflicting hosts may be able to retain its address. */
 
  if (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"));
 
    /* Active TCP sessions are aborted when removing the ip addresss */
    autoip_restart(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);
    autoip->lastconflict = DEFEND_INTERVAL * AUTOIP_TICKS_PER_SECOND;
  }
}
 
static void
autoip_create_addr(struct netif *netif, ip4_addr_t *ipaddr)
{
  struct autoip* autoip = netif_autoip_data(netif);
 
  /* 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 = lwip_ntohl(LWIP_AUTOIP_CREATE_SEED_ADDR(netif));
  addr += 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));
  ip4_addr_set_u32(ipaddr, lwip_htonl(addr));
 
  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
    ("autoip_create_addr(): tried_llipaddr=%"U16_F", %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
    (u16_t)(autoip->tried_llipaddr), ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr),
    ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr)));
}
 
static err_t
autoip_arp_probe(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
  /* this works because netif->ip_addr is ANY */
  return etharp_request(netif, &autoip->llipaddr);
}
 
static err_t
autoip_arp_announce(struct netif *netif)
{
  return etharp_gratuitous(netif);
}
 
static err_t
autoip_bind(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
  ip4_addr_t sn_mask, gw_addr;
 
  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
    ("autoip_bind(netif=%p) %c%c%"U16_F" %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
    (void*)netif, netif->name[0], netif->name[1], (u16_t)netif->num,
    ip4_addr1_16(&autoip->llipaddr), ip4_addr2_16(&autoip->llipaddr),
    ip4_addr3_16(&autoip->llipaddr), ip4_addr4_16(&autoip->llipaddr)));
 
  IP4_ADDR(&sn_mask, 255, 255, 0, 0);
  IP4_ADDR(&gw_addr, 0, 0, 0, 0);
 
  netif_set_addr(netif, &autoip->llipaddr, &sn_mask, &gw_addr);
  /* interface is used by routing now that an address is set */
 
  return ERR_OK;
}
 
err_t
autoip_start(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
  err_t result = ERR_OK;
 
  LWIP_ERROR("netif is not up, old style port?", netif_is_up(netif), return ERR_ARG;);
 
  /* Set IP-Address, Netmask and Gateway to 0 to make sure that
   * ARP Packets are formed correctly
   */
  netif_set_addr(netif, IP4_ADDR_ANY4, IP4_ADDR_ANY4, IP4_ADDR_ANY4);
 
  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 = (struct 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_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_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;
    ip4_addr_set_zero(&autoip->llipaddr);
    autoip->lastconflict = 0;
  }
 
  autoip_create_addr(netif, &(autoip->llipaddr));
  autoip_start_probing(netif);
 
  return result;
}
 
static void
autoip_start_probing(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
 
  autoip->state = AUTOIP_STATE_PROBING;
  autoip->sent_num = 0;
  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
     ("autoip_start_probing(): changing state to PROBING: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
      ip4_addr1_16(&autoip->llipaddr), ip4_addr2_16(&autoip->llipaddr),
      ip4_addr3_16(&autoip->llipaddr), ip4_addr4_16(&autoip->llipaddr)));
 
  /* time to wait to first probe, this is randomly
   * chosen 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
   * acquiring 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;
  }
}
 
void
autoip_network_changed(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
 
  if (autoip && (autoip->state != AUTOIP_STATE_OFF)) {
    autoip_start_probing(netif);
  }
}
 
err_t
autoip_stop(struct netif *netif)
{
  struct autoip* autoip = netif_autoip_data(netif);
 
  if (autoip != NULL) {
    autoip->state = AUTOIP_STATE_OFF;
    if (ip4_addr_islinklocal(netif_ip4_addr(netif))) {
      netif_set_addr(netif, IP4_ADDR_ANY4, IP4_ADDR_ANY4, IP4_ADDR_ANY4);
    }
  }
  return ERR_OK;
}
 
void
autoip_tmr(void)
{
  struct netif *netif = netif_list;
  /* loop through netif's */
  while (netif != NULL) {
    struct autoip* autoip = netif_autoip_data(netif);
    /* only act on AutoIP configured interfaces */
    if (autoip != NULL) {
      if (autoip->lastconflict > 0) {
        autoip->lastconflict--;
      }
 
      LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
        ("autoip_tmr() AutoIP-State: %"U16_F", ttw=%"U16_F"\n",
        (u16_t)(autoip->state), autoip->ttw));
 
      if (autoip->ttw > 0) {
        autoip->ttw--;
      }
 
      switch(autoip->state) {
        case AUTOIP_STATE_PROBING:
          if (autoip->ttw == 0) {
            if (autoip->sent_num >= PROBE_NUM) {
              /* Switch to ANNOUNCING: now we can bind to an IP address and use it */
              autoip->state = AUTOIP_STATE_ANNOUNCING;
              autoip_bind(netif);
              /* autoip_bind() calls netif_set_addr(): this triggers a gratuitous ARP
                 which counts as an announcement */
              autoip->sent_num = 1;
              autoip->ttw = ANNOUNCE_WAIT * AUTOIP_TICKS_PER_SECOND;
              LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
                 ("autoip_tmr(): changing state to ANNOUNCING: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
                  ip4_addr1_16(&autoip->llipaddr), ip4_addr2_16(&autoip->llipaddr),
                  ip4_addr3_16(&autoip->llipaddr), ip4_addr4_16(&autoip->llipaddr)));
            } else {
              autoip_arp_probe(netif);
              LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_tmr() PROBING Sent Probe\n"));
              autoip->sent_num++;
              if (autoip->sent_num == PROBE_NUM) {
                /* calculate time to wait to for announce */
                autoip->ttw = ANNOUNCE_WAIT * AUTOIP_TICKS_PER_SECOND;
              } else {
                /* calculate time to wait to next probe */
                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 (autoip->ttw == 0) {
            autoip_arp_announce(netif);
            LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_tmr() ANNOUNCING Sent Announce\n"));
            autoip->ttw = ANNOUNCE_INTERVAL * AUTOIP_TICKS_PER_SECOND;
            autoip->sent_num++;
 
            if (autoip->sent_num >= ANNOUNCE_NUM) {
                autoip->state = AUTOIP_STATE_BOUND;
                autoip->sent_num = 0;
                autoip->ttw = 0;
                 LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
                    ("autoip_tmr(): changing state to BOUND: %"U16_F".%"U16_F".%"U16_F".%"U16_F"\n",
                     ip4_addr1_16(&autoip->llipaddr), ip4_addr2_16(&autoip->llipaddr),
                     ip4_addr3_16(&autoip->llipaddr), ip4_addr4_16(&autoip->llipaddr)));
            }
          }
          break;
 
        default:
          /* nothing to do in other states */
          break;
      }
    }
    /* proceed to next network interface */
    netif = netif->next;
  }
}
 
void
autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr)
{
  struct autoip* autoip = netif_autoip_data(netif);
 
  LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_arp_reply()\n"));
  if ((autoip != NULL) && (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
    */
    ip4_addr_t sipaddr, dipaddr;
    struct eth_addr netifaddr;
    ETHADDR16_COPY(netifaddr.addr, netif->hwaddr);
 
    /* Copy struct ip4_addr2 to aligned ip4_addr, to support compilers without
     * structure packing (not using structure copy which breaks strict-aliasing rules).
     */
    IPADDR2_COPY(&sipaddr, &hdr->sipaddr);
    IPADDR2_COPY(&dipaddr, &hdr->dipaddr);
 
    if (autoip->state == AUTOIP_STATE_PROBING) {
     /* 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 ((ip4_addr_cmp(&sipaddr, &autoip->llipaddr)) ||
          (ip4_addr_isany_val(sipaddr) &&
           ip4_addr_cmp(&dipaddr, &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_restart(netif);
      }
    } else {
     /* RFC 3927 Section 2.5:
      * in any state we have a conflict if
      * ip.src == llipaddr && hw.src != own hwaddr
      */
      if (ip4_addr_cmp(&sipaddr, &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);
      }
    }
  }
}
 
u8_t
autoip_supplied_address(const struct netif *netif)
{
  if ((netif != NULL) && (netif_autoip_data(netif) != NULL)) {
    struct autoip* autoip = netif_autoip_data(netif);
    return (autoip->state == AUTOIP_STATE_BOUND) || (autoip->state == AUTOIP_STATE_ANNOUNCING);
  }
  return 0;
}
 
u8_t
autoip_accept_packet(struct netif *netif, const ip4_addr_t *addr)
{
  struct autoip* autoip = netif_autoip_data(netif);
  return (autoip != NULL) && ip4_addr_cmp(addr, &(autoip->llipaddr));
}
 
#endif /* LWIP_IPV4 && LWIP_AUTOIP */