/* From openssh 4.3p2 compat/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.
*/

/* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */

#include <config.h>

#ifndef HAVE_INET_NTOP

#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>

#ifndef IN6ADDRSZ
#define IN6ADDRSZ   16   /* IPv6 T_AAAA */
#endif

#ifndef INT16SZ
#define INT16SZ     2    /* for systems without 16-bit ints */
#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 *inet_ntop4(const u_char *src, char *dst, size_t size);
static const char *inet_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 *
inet_ntop(int af, const void *src, char *dst, size_t size)
{
       switch (af) {
       case AF_INET:
               return (inet_ntop4(src, dst, size));
       case AF_INET6:
               return (inet_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 *
inet_ntop4(const u_char *src, char *dst, size_t size)
{
       static const char fmt[] = "%u.%u.%u.%u";
       char tmp[sizeof "255.255.255.255"];
       int l;

       l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
       if (l <= 0 || l >= (int)size) {
               errno = ENOSPC;
               return (NULL);
       }
       strlcpy(dst, tmp, size);
       return (dst);
}

/* 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 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.
        */
       char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
       char *tp, *ep;
       struct { int base, len; } best, cur;
       u_int words[IN6ADDRSZ / INT16SZ];
       int i;
       int advance;

       /*
        * 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;
       ep = tmp + sizeof(tmp);
       for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; 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) {
                               if (tp + 1 >= ep)
                                       return (NULL);
                               *tp++ = ':';
                       }
                       continue;
               }
               /* Are we following an initial run of 0x00s or any real hex? */
               if (i != 0) {
                       if (tp + 1 >= ep)
                               return (NULL);
                       *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, (size_t)(ep - tp)))
                               return (NULL);
                       tp += strlen(tp);
                       break;
               }
               advance = snprintf(tp, ep - tp, "%x", words[i]);
               if (advance <= 0 || advance >= ep - tp)
                       return (NULL);
               tp += advance;
       }
       /* Was it a trailing run of 0x00's? */
       if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
               if (tp + 1 >= ep)
                       return (NULL);
               *tp++ = ':';
       }
       if (tp + 1 >= ep)
               return (NULL);
       *tp++ = '\0';

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

#endif /* !HAVE_INET_NTOP */

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