/*
 * dhcpcd - DHCP client daemon
 * Copyright 2006-2008 Roy Marples <roy@marples.name>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
 */

#include <arpa/inet.h>
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <time.h>

#include "config.h"
#include "common.h"
#include "duid.h"
#include "logger.h"

#ifdef ENABLE_DUID

#define THIRTY_YEARS_IN_SECONDS    946707779

size_t get_duid (unsigned char *duid, const interface_t *iface)
{
  FILE *f;
  uint16_t type = 0;
  uint16_t hw = 0;
  uint32_t ul;
  time_t t;
  int x = 0;
  unsigned char *p = duid;
  size_t len = 0;

  if (! iface)
    return (0);

  /* If we already have a DUID then use it as it's never supposed
   * to change once we have one even if the interfaces do */
  if ((f = fopen (DUIDFILE, "r")))
    {
      char *line = get_line (f);
      if (line)
        {
          len = hwaddr_aton (NULL, line);
          if (len && len <= DUID_LEN)
            hwaddr_aton (duid, line);
          free (line);
        }
      fclose (f);
      if (len)
        return (len);
    }
  else
    {
      if (errno != ENOENT)
        {
          logger (LOG_ERR, "fopen `%s': %s",
                  DUIDFILE, strerror (errno));
          return (0);
        }
    }

  /* No file? OK, lets make one based on our interface */
  type = htons (1); /* DUI-D-LLT */
  memcpy (p, &type, 2);
  p += 2;

  hw = htons (iface->family);
  memcpy (p, &hw, 2);
  p += 2;

  /* time returns seconds from jan 1 1970, but DUID-LLT is
   * seconds from jan 1 2000 modulo 2^32 */
  t = time (NULL) - THIRTY_YEARS_IN_SECONDS;
  ul = htonl (t & 0xffffffff);
  memcpy (p, &ul, 4);
  p += 4;

  /* Finally, add the MAC address of the interface */
  memcpy (p, iface->hwaddr, iface->hwlen);
  p += iface->hwlen;

  len = p - duid;

  if (! (f = fopen (DUIDFILE, "w")))
    logger (LOG_ERR, "fopen `%s': %s", DUIDFILE, strerror (errno));
  else
    {
      x = fprintf (f, "%s\n", hwaddr_ntoa (duid, len));
      fclose (f);
    }

  /* Failed to write the duid? scrub it, we cannot use it */
  if (x < 1)
    {
      len = 0;
      unlink (DUIDFILE);
    }

  return (len);
}
#endif