1/*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996-1999 by Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and 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
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#if defined(LIBC_SCCS) && !defined(lint)
19static const char rcsid[] = "$Id: inet_ntop.c,v 1.3.18.2 2005/11/03 23:02:22 marka Exp $";
20#endif /* LIBC_SCCS and not lint */
21#include <sys/cdefs.h>
22__FBSDID("$FreeBSD$");
23
24#include <sys/param.h>
25#include <sys/socket.h>
26#include <sys/systm.h>
27
28#include <netinet/in.h>
29
30/*%
31 * WARNING: Don't even consider trying to compile this on a system where
32 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
33 */
34
35static char	*inet_ntop4(const u_char *src, char *dst, socklen_t size);
36static char	*inet_ntop6(const u_char *src, char *dst, socklen_t size);
37
38/* char *
39 * inet_ntop(af, src, dst, size)
40 *	convert a network format address to presentation format.
41 * return:
42 *	pointer to presentation format address (`dst'), or NULL (see errno).
43 * author:
44 *	Paul Vixie, 1996.
45 */
46char *
47inet_ntop(int af, const void *src, char *dst, socklen_t size)
48{
49	switch (af) {
50	case AF_INET:
51		return (inet_ntop4(src, dst, size));
52	case AF_INET6:
53		return (inet_ntop6(src, dst, size));
54	default:
55		return (NULL);
56	}
57	/* NOTREACHED */
58}
59
60/* const char *
61 * inet_ntop4(src, dst, size)
62 *	format an IPv4 address
63 * return:
64 *	`dst' (as a const)
65 * notes:
66 *	(1) uses no statics
67 *	(2) takes a u_char* not an in_addr as input
68 * author:
69 *	Paul Vixie, 1996.
70 */
71static char *
72inet_ntop4(const u_char *src, char *dst, socklen_t size)
73{
74	static const char fmt[] = "%u.%u.%u.%u";
75	char tmp[sizeof "255.255.255.255"];
76	int l;
77
78	l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
79	if (l <= 0 || (socklen_t) l >= size) {
80		return (NULL);
81	}
82	strlcpy(dst, tmp, size);
83	return (dst);
84}
85
86/* const char *
87 * inet_ntop6(src, dst, size)
88 *	convert IPv6 binary address into presentation (printable) format
89 * author:
90 *	Paul Vixie, 1996.
91 */
92static char *
93inet_ntop6(const u_char *src, char *dst, socklen_t size)
94{
95	/*
96	 * Note that int32_t and int16_t need only be "at least" large enough
97	 * to contain a value of the specified size.  On some systems, like
98	 * Crays, there is no such thing as an integer variable with 16 bits.
99	 * Keep this in mind if you think this function should have been coded
100	 * to use pointer overlays.  All the world's not a VAX.
101	 */
102	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
103	struct { int base, len; } best, cur;
104#define NS_IN6ADDRSZ	16
105#define NS_INT16SZ	2
106	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
107	int i;
108
109	/*
110	 * Preprocess:
111	 *	Copy the input (bytewise) array into a wordwise array.
112	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
113	 */
114	memset(words, '\0', sizeof words);
115	for (i = 0; i < NS_IN6ADDRSZ; i++)
116		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
117	best.base = -1;
118	best.len = 0;
119	cur.base = -1;
120	cur.len = 0;
121	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
122		if (words[i] == 0) {
123			if (cur.base == -1)
124				cur.base = i, cur.len = 1;
125			else
126				cur.len++;
127		} else {
128			if (cur.base != -1) {
129				if (best.base == -1 || cur.len > best.len)
130					best = cur;
131				cur.base = -1;
132			}
133		}
134	}
135	if (cur.base != -1) {
136		if (best.base == -1 || cur.len > best.len)
137			best = cur;
138	}
139	if (best.base != -1 && best.len < 2)
140		best.base = -1;
141
142	/*
143	 * Format the result.
144	 */
145	tp = tmp;
146	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
147		/* Are we inside the best run of 0x00's? */
148		if (best.base != -1 && i >= best.base &&
149		    i < (best.base + best.len)) {
150			if (i == best.base)
151				*tp++ = ':';
152			continue;
153		}
154		/* Are we following an initial run of 0x00s or any real hex? */
155		if (i != 0)
156			*tp++ = ':';
157		/* Is this address an encapsulated IPv4? */
158		if (i == 6 && best.base == 0 && (best.len == 6 ||
159		    (best.len == 7 && words[7] != 0x0001) ||
160		    (best.len == 5 && words[5] == 0xffff))) {
161			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
162				return (NULL);
163			tp += strlen(tp);
164			break;
165		}
166		tp += sprintf(tp, "%x", words[i]);
167	}
168	/* Was it a trailing run of 0x00's? */
169	if (best.base != -1 && (best.base + best.len) ==
170	    (NS_IN6ADDRSZ / NS_INT16SZ))
171		*tp++ = ':';
172	*tp++ = '\0';
173
174	/*
175	 * Check for overflow, copy, and we're done.
176	 */
177	if ((socklen_t)(tp - tmp) > size) {
178		return (NULL);
179	}
180	strcpy(dst, tmp);
181	return (dst);
182}
183
184/*! \file */
185