1/*
2 * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1996-2001  Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18/*! \file */
19
20#if defined(LIBC_SCCS) && !defined(lint)
21static char rcsid[] =
22	"$Id: inet_ntop.c,v 1.19 2007/06/19 23:47:17 tbox Exp $";
23#endif /* LIBC_SCCS and not lint */
24
25#include <config.h>
26
27#include <errno.h>
28#include <stdio.h>
29#include <string.h>
30
31#include <isc/net.h>
32#include <isc/print.h>
33
34#include "ntp_sprintf.h"	/* NTP local change, helps SunOS 4 */
35
36#define NS_INT16SZ	 2
37#define NS_IN6ADDRSZ	16
38
39/*
40 * WARNING: Don't even consider trying to compile this on a system where
41 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
42 */
43
44static const char *inet_ntop4(const unsigned char *src, char *dst,
45			      size_t size);
46
47#ifdef AF_INET6
48static const char *inet_ntop6(const unsigned char *src, char *dst,
49			      size_t size);
50#endif
51
52/*! char *
53 * isc_net_ntop(af, src, dst, size)
54 *	convert a network format address to presentation format.
55 * \return
56 *	pointer to presentation format address (`dst'), or NULL (see errno).
57 * \author
58 *	Paul Vixie, 1996.
59 */
60const char *
61isc_net_ntop(int af, const void *src, char *dst, size_t size)
62{
63	switch (af) {
64	case AF_INET:
65		return (inet_ntop4(src, dst, size));
66#ifdef AF_INET6
67	case AF_INET6:
68		return (inet_ntop6(src, dst, size));
69#endif
70	default:
71		errno = EAFNOSUPPORT;
72		return (NULL);
73	}
74	/* NOTREACHED */
75}
76
77/*! const char *
78 * inet_ntop4(src, dst, size)
79 *	format an IPv4 address
80 * \return
81 *	`dst' (as a const)
82 * \note
83 *	(1) uses no statics
84 * \note
85 *	(2) takes a unsigned char* not an in_addr as input
86 * \author
87 *	Paul Vixie, 1996.
88 */
89static const char *
90inet_ntop4(const unsigned char *src, char *dst, size_t size)
91{
92	static const char *fmt = "%u.%u.%u.%u";
93	char tmp[sizeof("255.255.255.255")];
94
95	/* NTP local change to use SNPRINTF() macro for SunOS4 compat */
96	if (SNPRINTF((tmp, sizeof(tmp), fmt, src[0], src[1], src[2],
97		      src[3])) >= size)
98	{
99		errno = ENOSPC;
100		return (NULL);
101	}
102	strcpy(dst, tmp);
103
104	return (dst);
105}
106
107/*! const char *
108 * isc_inet_ntop6(src, dst, size)
109 *	convert IPv6 binary address into presentation (printable) format
110 * \author
111 *	Paul Vixie, 1996.
112 */
113#ifdef AF_INET6
114static const char *
115inet_ntop6(const unsigned char *src, char *dst, size_t size)
116{
117	/*
118	 * Note that int32_t and int16_t need only be "at least" large enough
119	 * to contain a value of the specified size.  On some systems, like
120	 * Crays, there is no such thing as an integer variable with 16 bits.
121	 * Keep this in mind if you think this function should have been coded
122	 * to use pointer overlays.  All the world's not a VAX.
123	 */
124	char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
125	struct { int base, len; } best, cur;
126	unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
127	int i;
128
129	/*
130	 * Preprocess:
131	 *	Copy the input (bytewise) array into a wordwise array.
132	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
133	 */
134	memset(words, '\0', sizeof(words));
135	for (i = 0; i < NS_IN6ADDRSZ; i++)
136		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
137	best.base = -1;
138	cur.base = -1;
139	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
140		if (words[i] == 0) {
141			if (cur.base == -1)
142				cur.base = i, cur.len = 1;
143			else
144				cur.len++;
145		} else {
146			if (cur.base != -1) {
147				if (best.base == -1 || cur.len > best.len)
148					best = cur;
149				cur.base = -1;
150			}
151		}
152	}
153	if (cur.base != -1) {
154		if (best.base == -1 || cur.len > best.len)
155			best = cur;
156	}
157	if (best.base != -1 && best.len < 2)
158		best.base = -1;
159
160	/*
161	 * Format the result.
162	 */
163	tp = tmp;
164	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
165		/* Are we inside the best run of 0x00's? */
166		if (best.base != -1 && i >= best.base &&
167		    i < (best.base + best.len)) {
168			if (i == best.base)
169				*tp++ = ':';
170			continue;
171		}
172		/* Are we following an initial run of 0x00s or any real hex? */
173		if (i != 0)
174			*tp++ = ':';
175		/* Is this address an encapsulated IPv4? */
176		if (i == 6 && best.base == 0 &&
177		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
178			if (!inet_ntop4(src+12, tp,
179					sizeof(tmp) - (tp - tmp)))
180				return (NULL);
181			tp += strlen(tp);
182			break;
183		}
184		tp += SPRINTF((tp, "%x", words[i]));	/* NTP local change */
185	}
186	/* Was it a trailing run of 0x00's? */
187	if (best.base != -1 && (best.base + best.len) ==
188	    (NS_IN6ADDRSZ / NS_INT16SZ))
189		*tp++ = ':';
190	*tp++ = '\0';
191
192	/*
193	 * Check for overflow, copy, and we're done.
194	 */
195	if ((size_t)(tp - tmp) > size) {
196		errno = ENOSPC;
197		return (NULL);
198	}
199	strcpy(dst, tmp);
200	return (dst);
201}
202#endif /* AF_INET6 */
203