/* inet_ntop.c -- convert IPv4 and IPv6 addresses from binary to text form

   Copyright (C) 2005-2006, 2008-2020 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU Lesser General Public License as published by

   the Free Software Foundation; either version 2.1, or (at your option)

   any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License

   along with this program; if not, see <https://www.gnu.org/licenses/>.  */

/*

 * Copyright (c) 1996-1999 by Internet Software Consortium.

 *

 * Permission to use, copy, modify, and distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS

 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE

 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL

 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR

 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS

 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

 * SOFTWARE.

 */

#include <config.h>

/* Specification.  */

#include <arpa/inet.h>

/* Use this to suppress gcc's "...may be used before initialized" warnings.

   Beware: The Code argument must not contain commas.  */

#ifndef IF_LINT

# if defined GCC_LINT || defined lint

#  define IF_LINT(Code) Code

# else

#  define IF_LINT(Code) /* empty */

# endif

#endif

#if HAVE_DECL_INET_NTOP

# undef inet_ntop

const char *

rpl_inet_ntop (int af, const void *restrict src,

               char *restrict dst, socklen_t cnt)

{

  return inet_ntop (af, src, dst, cnt);

}

#else

# include <stdio.h>

# include <string.h>

# include <errno.h>

# define NS_IN6ADDRSZ 16

# define NS_INT16SZ 2

/*

 * WARNING: Don't even consider trying to compile this on a system where

 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.

 */

typedef int verify_int_size[4 <= sizeof (int) ? 1 : -1];

static const char *inet_ntop4 (const unsigned char *src, char *dst, socklen_t size);

# if HAVE_IPV6

static const char *inet_ntop6 (const unsigned char *src, char *dst, socklen_t size);

# endif

/* char *

 * inet_ntop(af, src, dst, size)

 *      convert a network format address to presentation format.

 * return:

 *      pointer to presentation format address ('dst'), or NULL (see errno).

 * author:

 *      Paul Vixie, 1996.

 */

const char *

inet_ntop (int af, const void *restrict src,

           char *restrict dst, socklen_t cnt)

{

  switch (af)

    {

# if HAVE_IPV4

    case AF_INET:

      return (inet_ntop4 (src, dst, cnt));

# endif

# if HAVE_IPV6

    case AF_INET6:

      return (inet_ntop6 (src, dst, cnt));

# endif

    default:

      errno = EAFNOSUPPORT;

      return (NULL);

    }

  /* NOTREACHED */

}

/* const char *

 * inet_ntop4(src, dst, size)

 *      format an IPv4 address

 * return:

 *      'dst' (as a const)

 * notes:

 *      (1) uses no statics

 *      (2) takes a u_char* not an in_addr as input

 * author:

 *      Paul Vixie, 1996.

 */

static const char *

inet_ntop4 (const unsigned char *src, char *dst, socklen_t size)

{

  char tmp[sizeof "255.255.255.255"];

  int len;

  len = sprintf (tmp, "%u.%u.%u.%u", src[0], src[1], src[2], src[3]);

  if (len < 0)

    return NULL;

  if (len > size)

    {

      errno = ENOSPC;

      return NULL;

    }

  return strcpy (dst, tmp);

}

# if HAVE_IPV6

/* const char *

 * inet_ntop6(src, dst, size)

 *      convert IPv6 binary address into presentation (printable) format

 * author:

 *      Paul Vixie, 1996.

 */

static const char *

inet_ntop6 (const unsigned char *src, char *dst, socklen_t size)

{

  /*

   * Note that int32_t and int16_t need only be "at least" large enough

   * to contain a value of the specified size.  On some systems, like

   * Crays, there is no such thing as an integer variable with 16 bits.

   * Keep this in mind if you think this function should have been coded

   * to use pointer overlays.  All the world's not a VAX.

   */

  char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;

  struct

  {

    int base, len;

  } best, cur;

  unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];

  int i;

  /*

   * Preprocess:

   *      Copy the input (bytewise) array into a wordwise array.

   *      Find the longest run of 0x00's in src[] for :: shorthanding.

   */

  memset (words, '\0', sizeof words);

  for (i = 0; i < NS_IN6ADDRSZ; i += 2)

    words[i / 2] = (src[i] << 8) | src[i + 1];

  best.base = -1;

  cur.base = -1;

  IF_LINT(best.len = 0);

  IF_LINT(cur.len = 0);

  for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)

    {

      if (words[i] == 0)

        {

          if (cur.base == -1)

            cur.base = i, cur.len = 1;

          else

            cur.len++;

        }

      else

        {

          if (cur.base != -1)

            {

              if (best.base == -1 || cur.len > best.len)

                best = cur;

              cur.base = -1;

            }

        }

    }

  if (cur.base != -1)

    {

      if (best.base == -1 || cur.len > best.len)

        best = cur;

    }

  if (best.base != -1 && best.len < 2)

    best.base = -1;

  /*

   * Format the result.

   */

  tp = tmp;

  for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++)

    {

      /* Are we inside the best run of 0x00's? */

      if (best.base != -1 && i >= best.base && i < (best.base + best.len))

        {

          if (i == best.base)

            *tp++ = ':';

          continue;

        }

      /* Are we following an initial run of 0x00s or any real hex? */

      if (i != 0)

        *tp++ = ':';

      /* Is this address an encapsulated IPv4? */

      if (i == 6 && best.base == 0 &&

          (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))

        {

          if (!inet_ntop4 (src + 12, tp, sizeof tmp - (tp - tmp)))

            return (NULL);

          tp += strlen (tp);

          break;

        }

      {

        int len = sprintf (tp, "%x", words[i]);

        if (len < 0)

          return NULL;

        tp += len;

      }

    }

  /* Was it a trailing run of 0x00's? */

  if (best.base != -1 && (best.base + best.len) ==

      (NS_IN6ADDRSZ / NS_INT16SZ))

    *tp++ = ':';

  *tp++ = '\0';

  /*

   * Check for overflow, copy, and we're done.

   */

  if ((socklen_t) (tp - tmp) > size)

    {

      errno = ENOSPC;

      return NULL;

    }

  return strcpy (dst, tmp);

}

# endif

#endif