/*	Id: inet_ntop.c,v 1.4 2001/04/17 07:53:47 lukem Exp 	*/

/*	$NetBSD: inet_ntop.c,v 1.9 2000/01/22 22:19:16 mycroft Exp $	*/

/* 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 <net-snmp/net-snmp-config.h>

#if HAVE_ARPA_NAMESER_H

#include <arpa/nameser.h>

#endif

#include <errno.h>

#include <stdio.h>

#if HAVE_STRING_H

#include <string.h>

#else

#include <strings.h>

#endif

#include <net-snmp/types.h>

#include "inet_ntop.h"

#ifndef EAFNOSUPPORT

#define EAFNOSUPPORT            WSAEAFNOSUPPORT

#endif

#ifndef IN6ADDRSZ

#define	IN6ADDRSZ	16

#endif

#ifndef INT16SZ

#define	INT16SZ		2

#endif

#ifdef SPRINTF_CHAR

# define SPRINTF(x) strlen(sprintf/**/x)

#else

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

#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);

#ifdef NETSNMP_ENABLE_IPV6

static const char *inet_ntop6(const u_char *src, char *dst, size_t size);

#endif /* NETSNMP_ENABLE_IPV6 */

/* 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 *

netsnmp_inet_ntop(int af, const void *src, char *dst, size_t size)

{

	switch (af) {

	case AF_INET:

		return (inet_ntop4(src, dst, size));

#ifdef NETSNMP_ENABLE_IPV6

	case AF_INET6:

		return (inet_ntop6(src, dst, size));

#endif

	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"];

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

		errno = ENOSPC;

		return (NULL);

	}

	strcpy(dst, tmp);

	return (dst);

}

#ifdef NETSNMP_ENABLE_IPV6

/* 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"], *tp;

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

	u_int words[IN6ADDRSZ / 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 < 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 (!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) == (IN6ADDRSZ / 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);

}

#endif