/**
 * @file
 * AutoIP Automatic LinkLocal IP Configuration
 *
 * This is a AutoIP implementation for the lwIP TCP/IP stack. It aims to conform
 * with RFC 3927. It uses IPv4 address conflict detection to evaluate the chosen
 * address. The ACD module aims to be conform to RFC 5227.
 * RFC 5227 is extracted out of RFC 3927 so the acd module fits nicely in autoip.
 *
 * @defgroup autoip AUTOIP
 * @ingroup ip4
 * AUTOIP related functions
 * USAGE:
 *
 * define @ref LWIP_AUTOIP 1 in your lwipopts.h
 *
 * Without DHCP:
 * - Call autoip_start() after netif_add().
 *
 * With DHCP:
 * - define @ref LWIP_DHCP_AUTOIP_COOP 1 in your lwipopts.h.
 * - Configure your DHCP Client.
 *
 * @see netifapi_autoip
 */

/*
 *
 * 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 "lwip/opt.h"

#if LWIP_IPV4 && 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 "lwip/acd.h"
#include "lwip/etharp.h"
#include "lwip/prot/autoip.h"

#include <string.h>

/**
 * 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) \
  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 */

/* Function definitions */
static void autoip_restart(struct netif *netif);
static void autoip_create_addr(struct netif *netif, ip4_addr_t *ipaddr);
static err_t autoip_bind(struct netif *netif);
static void autoip_conflict_callback(struct netif *netif,
                                     acd_callback_enum_t state);

/**
 * @ingroup autoip
 * Set a statically allocated struct autoip to work with.
 * Using this prevents autoip_start to allocate it using mem_malloc.
 *
 * @param netif the netif for which to set the struct autoip
 * @param autoip (uninitialised) autoip struct allocated by the application
 */
void
autoip_set_struct(struct netif *netif, struct autoip *autoip)
{
  LWIP_ASSERT_CORE_LOCKED();
  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);
}

/**
 * @ingroup autoip
 * Remove a struct autoip previously set to the netif using autoip_set_struct()
 *
 * @param netif the netif for which to set the struct autoip
 */
void
autoip_remove_struct(struct netif *netif)
{
  LWIP_ASSERT_CORE_LOCKED();
  LWIP_ASSERT("netif != NULL", netif != NULL);
  LWIP_ASSERT("netif has no struct autoip set",
              netif_autoip_data(netif) != NULL);

  netif_set_client_data(netif, LWIP_NETIF_CLIENT_DATA_INDEX_AUTOIP, NULL);
}

/** Restart AutoIP client and check the next address (conflict detected)
 *
 * @param netif The netif under AutoIP control
 */
static void
autoip_restart(struct netif *netif)
{
  struct autoip *autoip = netif_autoip_data(netif);
  autoip->tried_llipaddr++;
  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, 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)));
}


/**
 * 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_data(netif);
  ip4_addr_t sn_mask, gw_addr;

  autoip->state = AUTOIP_STATE_BOUND;

  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;
}

/**
* Handle conflict information from ACD module
*
* @param netif   network interface to handle conflict information on
* @param state   acd_callback_enum_t
 */
static void
autoip_conflict_callback(struct netif *netif, acd_callback_enum_t state)
{
  struct autoip *autoip = netif_autoip_data(netif);

  switch (state) {
    case ACD_IP_OK:
      autoip_bind(netif);
      break;
    case ACD_RESTART_CLIENT:
      autoip_restart(netif);
      break;
    case ACD_DECLINE:
      /* "delete" conflicting address so a new one will be selected in
       * autoip_start() */
      ip4_addr_set_any(&autoip->llipaddr);
      autoip_stop(netif);
      break;
      default:
      break;
  }
}

/**
 * @ingroup autoip
 * 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_data(netif);
  err_t result = ERR_OK;

  LWIP_ASSERT_CORE_LOCKED();
  LWIP_ERROR("netif is not up, old style port?", netif_is_up(netif), return ERR_ARG;);

  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_calloc(1, sizeof(struct autoip));
    if (autoip == NULL) {
      LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                  ("autoip_start(): could not allocate autoip\n"));
      return ERR_MEM;
    }
    /* 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"));
  }

  if (autoip->state == AUTOIP_STATE_OFF) {
    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));

    /* add acd struct to list*/
    acd_add(netif, &autoip->acd, autoip_conflict_callback);

    /* In accordance to RFC3927 section 2.1:
     * Keep using the same link local address as much as possible.
     * Only when there is none or when there was a conflict, select a new one.
     */
    if (!ip4_addr_islinklocal(&autoip->llipaddr)) {
      autoip_create_addr(netif, &(autoip->llipaddr));
    }
    autoip->state = AUTOIP_STATE_CHECKING;
    acd_start(netif, &autoip->acd, autoip->llipaddr);
  } else {
    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE,
                ("autoip_start(): already started on netif=%p %c%c%"U16_F"\n",
                (void *)netif, netif->name[0],
                 netif->name[1], (u16_t)netif->num));
  }

  return result;
}


/**
 * Handle a possible change in the network configuration: link up
 *
 * If there is an AutoIP address configured and AutoIP is not in cooperation
 * with DHCP, start probing for previous address.
 */
void
autoip_network_changed_link_up(struct netif *netif)
{
  struct autoip *autoip = netif_autoip_data(netif);

  if (autoip && (autoip->state != AUTOIP_STATE_OFF) && !LWIP_DHCP_AUTOIP_COOP) {
    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                ("autoip_network_changed_link_up(): start acd"));
    autoip->state = AUTOIP_STATE_CHECKING;
    /* Start acd check again for the last used address */
    acd_start(netif, &autoip->acd, autoip->llipaddr);
  }
}

/**
 * Handle a possible change in the network configuration: link down
 *
 * If there is an AutoIP address configured and AutoIP is in cooperation
 * with DHCP, then stop the autoip module. When the link goes up, we do not want
 * the autoip module to start again. DHCP will initiate autoip when needed.
 */
void
autoip_network_changed_link_down(struct netif *netif)
{
  struct autoip *autoip = netif_autoip_data(netif);

  if (autoip && (autoip->state != AUTOIP_STATE_OFF) && LWIP_DHCP_AUTOIP_COOP) {
    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,
                ("autoip_network_changed_link_down(): stop autoip"));
    autoip_stop(netif);
  }
}

/**
 * @ingroup autoip
 * Stop AutoIP client
 *
 * @param netif network interface on which stop the AutoIP client
 */
err_t
autoip_stop(struct netif *netif)
{
  struct autoip *autoip = netif_autoip_data(netif);

  LWIP_ASSERT_CORE_LOCKED();
  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);
    }
    LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE,("autoip_stop()"));
  }
  return ERR_OK;
}

/** check if AutoIP supplied netif->ip_addr
 *
 * @param netif the netif to check
 * @return 1 if AutoIP supplied netif->ip_addr (state BOUND),
 *         0 otherwise
 */
u8_t
autoip_supplied_address(struct netif *netif)
{
  struct autoip *autoip = netif_autoip_data(netif);
  return     (autoip != NULL)
          && (ip4_addr_eq(netif_ip4_addr(netif), &(autoip->llipaddr)))
          && (autoip->state == AUTOIP_STATE_BOUND);
}

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_eq(addr, &(autoip->llipaddr)))
          && (autoip->state == AUTOIP_STATE_BOUND);
}

#endif /* LWIP_IPV4 && LWIP_AUTOIP */
