/* This is from the BIND 4.9.4 release, modified to compile by itself */
/* Modified again 2003-03-27 Jeff Connelly to compile under 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$Id: inet_ntop.c,v $";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>

#ifdef _WIN32
#include <winsock2.h>
#if !defined EAFNOSUPPORT
   #define EAFNOSUPPORT 97
#endif
//#define ENOSPC 98
#else
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#endif

#define	IN6ADDRSZ	16
#define	INT16SZ		 2

#ifndef	AF_INET6
#define	AF_INET6	AF_MAX+1	/* just to let this compile */
#endif

/*
 * 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 *myinet_ntop4(const u_char *src, char *dst, size_t size);
static const char *myinet_ntop6(const u_char *src, char *dst, size_t size);

/* 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 *
myinet_ntop(int af, const void* src, char* dst, size_t size)
{
   switch (af) {
   case AF_INET:
      return (myinet_ntop4(src, dst, size));
   case AF_INET6:
      return (myinet_ntop6(src, dst, size));
   default:
      errno = 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 u_char* not an in_addr as input
 * author:
 *	Paul Vixie, 1996.
 */
static const char *
myinet_ntop4(const u_char* src, char* dst, size_t size)
{
   static const char fmt[] = "%u.%u.%u.%u";
   size_t maxlen = sizeof "255.255.255.255";
   char tmp[sizeof "255.255.255.255"];
   #if defined(_WINDOWS)
   sprintf_s(tmp, maxlen, fmt, src[0], src[1], src[2], src[3]);
   #else
   snprintf(tmp, maxlen, fmt, src[0], src[1], src[2], src[3]);
   #endif
   if (strlen(tmp) > size) {
      errno = ENOSPC;
      return (NULL);
   }
   #if defined(_WINDOWS)
   strcpy_s(dst, maxlen, tmp);
   #else
   strncpy(dst, tmp, maxlen);
   #endif
   return (dst);
}

/* const char *
 * inet_ntop6(src, dst, size)
 *	convert IPv6 binary address into presentation (printable) format
 * author:
 *	Paul Vixie, 1996.
 */
static const char *
myinet_ntop6(const u_char* 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.
    */
   const size_t maxlen = sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255";
   char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
   struct { int base, len; } best, cur;
   u_int words[IN6ADDRSZ / INT16SZ];
   int i;
   best.len = 0;

   /*
    * 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 < IN6ADDRSZ; i++)
      words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
   best.base = -1;
   cur.base = -1;
   for (i = 0; i < (IN6ADDRSZ / 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 < (IN6ADDRSZ / 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 (!myinet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
            return (NULL);
         tp += strlen(tp);
         break;
      }
      #if defined(_WINDOWS)
      sprintf_s(tp, 5, "%x", words[i]);
      #else
      snprintf(tp, 5, "%x", words[i]);
      #endif
      tp += strlen(tp);
   }
   /* Was it a trailing run of 0x00's? */
   if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
      *tp++ = ':';
   *tp++ = '\0';

   /*
    * Check for overflow, copy, and we're done.
    */
   if ((tp - tmp) > (signed int) size) {
      errno = ENOSPC;
      return (NULL);
   }
   #if defined(_WINDOWS)
   strcpy_s(dst, maxlen, tmp);
   #else
   strncpy(dst, tmp, maxlen);
   #endif

   return (dst);
}
