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 */
199