inet_ntop.c   [plain text]

/*
 * Copyright (c) 2003,2005,2006,2011,2012 Apple, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1996-1999 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 ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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 <arpa/inet.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <netinet/in.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>

#define MAX_V4_ADDR_LEN 16

const char * inet_ntop6(const struct in6_addr *addr, char *dst, socklen_t size);
const char * inet_ntop4(const struct in_addr *addr, char *dst, socklen_t size);

const char *
inet_ntop(int af, const void *addr, char *buf, socklen_t len)
{
	if (addr && af == AF_INET6) return inet_ntop6(addr, buf, len);
	if (addr && af == AF_INET) return inet_ntop4(addr, buf, len);

	errno = EAFNOSUPPORT;
	return NULL;
}

/* const char *
 * inet_ntop6(src, dst, size)
 *	convert IPv6 binary address into presentation (printable) format
 * author:
 *	Paul Vixie, 1996.
 */
const char *
inet_ntop6(const struct in6_addr *addr, char *dst, socklen_t size)
{
	const u_char *src = addr->__u6_addr.__u6_addr8;
	/*
	 * 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;
	best.len = 0;
	cur.base = -1;
	cur.len = 0;
	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 == 7 && words[7] != 0x0001) ||
				(best.len == 5 && words[5] == 0xffff))) {
			struct in_addr ipv4_addr;
			memcpy(&ipv4_addr, src+12, sizeof(ipv4_addr));
			if (!inet_ntop4(&ipv4_addr, tp, (socklen_t)sizeof(tmp) - (socklen_t)(tp - tmp))) {
				errno = ENOSPC;
				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 ((socklen_t)(tp - tmp) > size) {
		errno = ENOSPC;
		return (NULL);
	}
	strcpy(dst, tmp);
	return (dst);
}

const char *
inet_ntop4(const struct in_addr *addr, char *dst, socklen_t size)
{
	char tmp[MAX_V4_ADDR_LEN], *p;
	const u_int8_t *ap = (u_int8_t *)&addr->s_addr;
	int i;
	size_t ql, len;

	if (addr == NULL) {
		errno = EAFNOSUPPORT;
		return NULL;
	}

	if (dst == NULL) {
		errno = ENOSPC;
		return NULL;
	}

	memset(tmp, 0, MAX_V4_ADDR_LEN);

	/* 3 dots, trailing nul */
	len = 4;

	p = tmp;

	for (i = 0; i < 4; i++, ap++) {
		snprintf(p, 4, "%d", *ap);
		ql = strlen(p);
		len += ql;
		p += ql;
		if (i < 3) *p++ = '.';
	}

	if (len > size) {
		errno = ENOSPC;
		return NULL;
	}

	memcpy(dst, tmp, len);
	return dst;
}