lib/inet_pton.c

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

   Copyright (C) 2006, 2008-2026 Free Software Foundation, Inc.

   This file 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 of the
   License, or (at your option) any later version.

   This file 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>

#if HAVE_DECL_INET_PTON

# undef inet_pton

int
rpl_inet_pton (int af, const char *restrict src, void *restrict dst)
{
  return inet_pton (af, src, dst);
}

#else

# include <c-ctype.h>
# include <string.h>
# include <errno.h>

# define NS_INADDRSZ 4
# 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.
 */

static int inet_pton4 (const char *src, unsigned char *dst);
# if HAVE_IPV6
static int inet_pton6 (const char *src, unsigned char *dst);
# endif

/* int
 * inet_pton(af, src, dst)
 *      convert from presentation format (which usually means ASCII printable)
 *      to network format (which is usually some kind of binary format).
 * return:
 *      1 if the address was valid for the specified address family
 *      0 if the address wasn't valid ('dst' is untouched in this case)
 *      -1 if some other error occurred ('dst' is untouched in this case, too)
 * author:
 *      Paul Vixie, 1996.
 */
int
inet_pton (int af, const char *restrict src, void *restrict dst)
{
  switch (af)
    {
    case AF_INET:
      return (inet_pton4 (src, dst));

# if HAVE_IPV6
    case AF_INET6:
      return (inet_pton6 (src, dst));
# endif

    default:
      errno = EAFNOSUPPORT;
      return (-1);
    }
  /* NOTREACHED */
}

/* int
 * inet_pton4(src, dst)
 *      like inet_aton() but without all the hexadecimal, octal (with the
 *      exception of 0) and shorthand.
 * return:
 *      1 if 'src' is a valid dotted quad, else 0.
 * notice:
 *      does not touch 'dst' unless it's returning 1.
 * author:
 *      Paul Vixie, 1996.
 */
static int
inet_pton4 (const char *restrict src, unsigned char *restrict dst)
{
  unsigned char tmp[NS_INADDRSZ];

  {
    int saw_digit = 0;
    int octets = 0;
    unsigned char *tp = tmp;
    *tp = 0;
    int ch;
    while ((ch = *src++) != '\0')
      {
        if (ch >= '0' && ch <= '9')
          {
            if (saw_digit && *tp == 0)
              return (0);
            unsigned new = *tp * 10 + (ch - '0');
            if (new > 255)
              return (0);
            *tp = new;
            if (!saw_digit)
              {
                if (++octets > 4)
                  return (0);
                saw_digit = 1;
              }
          }
        else if (ch == '.' && saw_digit)
          {
            if (octets == 4)
              return (0);
            *++tp = 0;
            saw_digit = 0;
          }
        else
          return (0);
      }
    if (octets < 4)
      return (0);
  }
  memcpy (dst, tmp, NS_INADDRSZ);
  return (1);
}

# if HAVE_IPV6

/* int
 * inet_pton6(src, dst)
 *      convert presentation level address to network order binary form.
 * return:
 *      1 if 'src' is a valid [RFC1884 2.2] address, else 0.
 * notice:
 *      (1) does not touch 'dst' unless it's returning 1.
 *      (2) :: in a full address is silently ignored.
 * credit:
 *      inspired by Mark Andrews.
 * author:
 *      Paul Vixie, 1996.
 */
static int
inet_pton6 (const char *restrict src, unsigned char *restrict dst)
{
  static const char xdigits[] = "0123456789abcdef";
  unsigned char tmp[NS_IN6ADDRSZ];

  /* Leading :: requires some special handling. */
  if (*src == ':')
    if (*++src != ':')
      return (0);

  {
    unsigned char *tp = memset (tmp, '\0', NS_IN6ADDRSZ);
    unsigned char *endp = tp + NS_IN6ADDRSZ;
    unsigned char *colonp = NULL;
    const char *curtok = src;
    int saw_xdigit = 0;
    unsigned int val = 0;
    int ch;
    while ((ch = c_tolower (*src++)) != '\0')
      {
        const char *pch = strchr (xdigits, ch);
        if (pch != NULL)
          {
            val <<= 4;
            val |= (pch - xdigits);
            if (val > 0xffff)
              return (0);
            saw_xdigit = 1;
          }
        else if (ch == ':')
          {
            curtok = src;
            if (!saw_xdigit)
              {
                if (colonp)
                  return (0);
                colonp = tp;
              }
            else if (*src == '\0')
              return (0);
            else if (tp + NS_INT16SZ > endp)
              return (0);
            else
              {
                *tp++ = (unsigned char) (val >> 8) & 0xff;
                *tp++ = (unsigned char) val & 0xff;
                saw_xdigit = 0;
                val = 0;
              }
          }
        else if (ch == '.' && ((tp + NS_INADDRSZ) <= endp) &&
            inet_pton4 (curtok, tp) > 0)
          {
            tp += NS_INADDRSZ;
            saw_xdigit = 0;
            break;                /* '\0' was seen by inet_pton4(). */
          }
        else
          return (0);
      }
    if (saw_xdigit)
      {
        if (tp + NS_INT16SZ > endp)
          return (0);
        *tp++ = (unsigned char) (val >> 8) & 0xff;
        *tp++ = (unsigned char) val & 0xff;
      }
    if (colonp != NULL)
      {
        if (tp == endp)
          return (0);
        /*
         * Since some memmove()'s erroneously fail to handle
         * overlapping regions, we'll do the shift by hand.
         */
        const int n = tp - colonp;
        for (int i = 1; i <= n; i++)
          {
            endp[-i] = colonp[n - i];
            colonp[n - i] = 0;
          }
        tp = endp;
      }
    if (tp != endp)
      return (0);
  }
  memcpy (dst, tmp, NS_IN6ADDRSZ);
  return (1);
}

# endif

#endif