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/* 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 1.2 2001-09-27 12:01:53 chris Exp $";

#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <arpa/nameser.h>

#include <errno.h>

#include <stdio.h>

#include <string.h>

#define SPRINTF(x) ((size_t)sprintf x)

/*

 * 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 __P((const u_char *src, char *dst, size_t size));

static const char *inet_ntop6 __P((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(af, src, dst, size)

        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(src, dst, size)

        const u_char *src;

        char *dst;

        size_t size;

{

        static const char fmt[] = "%u.%u.%u.%u";

        char tmp[sizeof "255.255.255.255"];

        if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) {

                errno = ENOSPC;

                return (NULL);

        }

        strcpy(dst, tmp);

        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(src, dst, size)

        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"], *tp;

        struct { int base, len; } best, cur;

        u_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++)

                words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));

        best.base = -1;

        cur.base = -1;

        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;

                }

                tp += SPRINTF((tp, "%x", words[i]));

        }

        /* 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 ((size_t)(tp - tmp) > size) {

                errno = ENOSPC;

                return (NULL);

        }

        strcpy(dst, tmp);

        return (dst);

}