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inet_ntop.c
/* Copyright (c) 1996 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"

#include <ctype.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <sys/types.h>

#include "sofia-sip/su.h"

/*
 * 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 const char *inet_ntop4(const unsigned char *src, char *dst, size_t size);
#if HAVE_SIN6
static const char *inet_ntop6(const unsigned char *src, char *dst, size_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.
 */

/** inet_ntop() replacement.
 *
 * Convert a network format address to presentation format.
 *
 * @param af[in] address family
 * @param src[in] network address to convert
 * @param dst[out] return-value string
 * @param size[in] maximum lenght of @a dst string
 *
 * @return Pointer to presentation format address (`dst'), or NULL (see errno).
 *
 * @author Paul Vixie, 1996.
 *
 * @NEW_1_12_9
 */
const char *
su_inet_ntop(int af, void const *src, char *dst, size_t size)
{

      switch (af) {
      case AF_INET:
            return inet_ntop4(src, dst, size);
#if HAVE_SIN6
      case AF_INET6:
            return inet_ntop6(src, dst, size);
#endif
      default:
            su_seterrno(EAFNOSUPPORT);
            return NULL;
      }
      /* NOTREACHED */
}

/* const char *
 * inet_ntop4(src, dst, size)
 *    format an IPv4 address, more or less like inet_ntoa()
 * return:
 *    `dst' (as a const)
 * notes:
 *    (1) uses no statics
 *    (2) takes a unsigned char* not an in_addr as input
 * author:
 *    Paul Vixie, 1996.
 */
static const char *
inet_ntop4(const unsigned char *src, char *dst, size_t size)
{
      static const char fmt[] = "%u.%u.%u.%u";
      char tmp[sizeof "255.255.255.255"];

      if (snprintf(tmp, sizeof tmp, fmt,
                 src[0], src[1], src[2], src[3]) >= size) {
            su_seterrno(ENOSPC);
            return NULL;
      }

      return strcpy(dst, tmp);
}

#if HAVE_SIN6
/* const char *
 * inet_ntop6(src, dst, size)
 *    convert IPv6 binary address into presentation (printable) format
 * author:
 *    Paul Vixie, 1996.
 */
static const char *
inet_ntop6(unsigned char const *src, char *dst, size_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 = { -1 , 0 }, cur = { -1, 0 };
      unsigned int words[8];
      int i;

      /*
       * Preprocess:
       *    Copy the input (bytewise) array into a wordwise array.
       *    Find the longest run of 0x00's in src[] for :: shorthanding.
       */
      for (i = 0; i < 16; i += 2)
            words[i / 2] = (src[i] << 8) | (src[i + 1]);
      best.base = -1;
      cur.base = -1;
      for (i = 0; i < 8; 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 < 8; 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;
            }
            tp += sprintf(tp, "%x", words[i]);
      }
      /* Was it a trailing run of 0x00's? */
      if (best.base != -1 && (best.base + best.len) == 8)
            *tp++ = ':';
      *tp++ = '\0';

      /*
       * Check for overflow, copy, and we're done.
       */
      if ((size_t)(tp - tmp) >= size) {
            su_seterrno(ENOSPC);
            return NULL;
      }

      return strcpy(dst, tmp);
}
#endif

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