/contrib/ntp/libisc/inet_ntop.c

  1/*
  2 * Copyright (C) 1996-2001  Internet Software Consortium.
  3 *
  4 * Permission to use, copy, modify, and distribute this software for any
  5 * purpose with or without fee is hereby granted, provided that the above
  6 * copyright notice and this permission notice appear in all copies.
  7 *
  8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
  9 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 10 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 11 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
 12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 13 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 14 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 15 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 16 */
 17
 18#if defined(LIBC_SCCS) && !defined(lint)
 19static char rcsid[] =
 20	"$Id: inet_ntop.c,v 1.13 2001/11/27 01:56:00 gson Exp $";
 21#endif /* LIBC_SCCS and not lint */
 22
 23#include <config.h>
 24
 25#include <errno.h>
 26#include <stdio.h>
 27#include <string.h>
 28
 29#include <isc/net.h>
 30
 31#include "ntp_sprintf.h"
 32
 33#define NS_INT16SZ	 2
 34#define NS_IN6ADDRSZ	16
 35
 36/*
 37 * WARNING: Don't even consider trying to compile this on a system where
 38 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
 39 */
 40
 41static const char *inet_ntop4(const unsigned char *src, char *dst,
 42			      size_t size);
 43
 44#ifdef AF_INET6
 45static const char *inet_ntop6(const unsigned char *src, char *dst,
 46			      size_t size);
 47#endif
 48
 49/* char *
 50 * isc_net_ntop(af, src, dst, size)
 51 *	convert a network format address to presentation format.
 52 * return:
 53 *	pointer to presentation format address (`dst'), or NULL (see errno).
 54 * author:
 55 *	Paul Vixie, 1996.
 56 */
 57const char *
 58isc_net_ntop(int af, const void *src, char *dst, size_t size)
 59{
 60	switch (af) {
 61	case AF_INET:
 62		return (inet_ntop4(src, dst, size));
 63#ifdef AF_INET6
 64	case AF_INET6:
 65		return (inet_ntop6(src, dst, size));
 66#endif
 67	default:
 68		errno = EAFNOSUPPORT;
 69		return (NULL);
 70	}
 71	/* NOTREACHED */
 72}
 73
 74/* const char *
 75 * inet_ntop4(src, dst, size)
 76 *	format an IPv4 address
 77 * return:
 78 *	`dst' (as a const)
 79 * notes:
 80 *	(1) uses no statics
 81 *	(2) takes a unsigned char* not an in_addr as input
 82 * author:
 83 *	Paul Vixie, 1996.
 84 */
 85static const char *
 86inet_ntop4(const unsigned char *src, char *dst, size_t size)
 87{
 88	static const char *fmt = "%u.%u.%u.%u";
 89	char tmp[sizeof("255.255.255.255")];
 90
 91	if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size)
 92	{
 93		errno = ENOSPC;
 94		return (NULL);
 95	}
 96	strcpy(dst, tmp);
 97
 98	return (dst);
 99}
100
101/* const char *
102 * isc_inet_ntop6(src, dst, size)
103 *	convert IPv6 binary address into presentation (printable) format
104 * author:
105 *	Paul Vixie, 1996.
106 */
107#ifdef AF_INET6
108static const char *
109inet_ntop6(const unsigned char *src, char *dst, size_t size)
110{
111	/*
112	 * Note that int32_t and int16_t need only be "at least" large enough
113	 * to contain a value of the specified size.  On some systems, like
114	 * Crays, there is no such thing as an integer variable with 16 bits.
115	 * Keep this in mind if you think this function should have been coded
116	 * to use pointer overlays.  All the world's not a VAX.
117	 */
118	char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
119	struct { int base, len; } best, cur;
120	unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
121	int i;
122
123	/*
124	 * Preprocess:
125	 *	Copy the input (bytewise) array into a wordwise array.
126	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
127	 */
128	memset(words, '\0', sizeof(words));
129	for (i = 0; i < NS_IN6ADDRSZ; i++)
130		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
131	best.base = -1;
132	best.len = 0;
133	cur.base = -1;
134	cur.len = 0;
135	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
136		if (words[i] == 0) {
137			if (cur.base == -1)
138				cur.base = i, cur.len = 1;
139			else
140				cur.len++;
141		} else {
142			if (cur.base != -1) {
143				if (best.base == -1 || cur.len > best.len)
144					best = cur;
145				cur.base = -1;
146			}
147		}
148	}
149	if (cur.base != -1) {
150		if (best.base == -1 || cur.len > best.len)
151			best = cur;
152	}
153	if (best.base != -1 && best.len < 2)
154		best.base = -1;
155
156	/*
157	 * Format the result.
158	 */
159	tp = tmp;
160	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
161		/* Are we inside the best run of 0x00's? */
162		if (best.base != -1 && i >= best.base &&
163		    i < (best.base + best.len)) {
164			if (i == best.base)
165				*tp++ = ':';
166			continue;
167		}
168		/* Are we following an initial run of 0x00s or any real hex? */
169		if (i != 0)
170			*tp++ = ':';
171		/* Is this address an encapsulated IPv4? */
172		if (i == 6 && best.base == 0 &&
173		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
174			if (!inet_ntop4(src+12, tp,
175					sizeof(tmp) - (tp - tmp)))
176				return (NULL);
177			tp += strlen(tp);
178			break;
179		}
180		tp += SPRINTF((tp, "%x", words[i]));
181	}
182	/* Was it a trailing run of 0x00's? */
183	if (best.base != -1 && (best.base + best.len) ==
184	    (NS_IN6ADDRSZ / NS_INT16SZ))
185		*tp++ = ':';
186	*tp++ = '\0';
187
188	/*
189	 * Check for overflow, copy, and we're done.
190	 */
191	if ((size_t)(tp - tmp) > size) {
192		errno = ENOSPC;
193		return (NULL);
194	}
195	strcpy(dst, tmp);
196	return (dst);
197}
198#endif /* AF_INET6 */