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 1.5 2005/11/03 22:59:52 marka Exp $";
20#endif /* LIBC_SCCS and not lint */
21
22#include <sys/param.h>
23#include <sys/types.h>
24#include <sys/socket.h>
25
26#include <netinet/in.h>
27#include <arpa/inet.h>
28#include <arpa/nameser.h>
29
30#include <errno.h>
31#include <stdio.h>
32#include <string.h>
33
34#ifdef SPRINTF_CHAR
35# define SPRINTF(x) strlen(sprintf/**/x)
36#else
37# define SPRINTF(x) ((size_t)sprintf x)
38#endif
39
40/*%
41 * WARNING: Don't even consider trying to compile this on a system where
42 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
43 */
44
45static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
46static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
47
48/* char *
49 * inet_ntop(af, src, dst, size)
50 *	convert a network format address to presentation format.
51 * return:
52 *	pointer to presentation format address (`dst'), or NULL (see errno).
53 * author:
54 *	Paul Vixie, 1996.
55 */
56const char *
57inet_ntop(af, src, dst, size)
58	int af;
59	const void *src;
60	char *dst;
61	socklen_t size;
62{
63	switch (af) {
64	case AF_INET:
65		return (inet_ntop4(src, dst, size));
66	case AF_INET6:
67		return (inet_ntop6(src, dst, size));
68	default:
69		errno = EAFNOSUPPORT;
70		return (NULL);
71	}
72	/* NOTREACHED */
73}
74
75/* const char *
76 * inet_ntop4(src, dst, size)
77 *	format an IPv4 address
78 * return:
79 *	`dst' (as a const)
80 * notes:
81 *	(1) uses no statics
82 *	(2) takes a u_char* not an in_addr as input
83 * author:
84 *	Paul Vixie, 1996.
85 */
86static const char *
87inet_ntop4(src, dst, size)
88	const u_char *src;
89	char *dst;
90	size_t size;
91{
92	static const char fmt[] = "%u.%u.%u.%u";
93	char tmp[sizeof "255.255.255.255"];
94
95	if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
96		errno = ENOSPC;
97		return (NULL);
98	}
99	strcpy(dst, tmp);
100	return (dst);
101}
102
103/* const char *
104 * inet_ntop6(src, dst, size)
105 *	convert IPv6 binary address into presentation (printable) format
106 * author:
107 *	Paul Vixie, 1996.
108 */
109static const char *
110inet_ntop6(src, dst, size)
111	const u_char *src;
112	char *dst;
113	size_t size;
114{
115	/*
116	 * Note that int32_t and int16_t need only be "at least" large enough
117	 * to contain a value of the specified size.  On some systems, like
118	 * Crays, there is no such thing as an integer variable with 16 bits.
119	 * Keep this in mind if you think this function should have been coded
120	 * to use pointer overlays.  All the world's not a VAX.
121	 */
122	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
123	struct { int base, len; } best, cur;
124	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
125	int i;
126
127	/*
128	 * Preprocess:
129	 *	Copy the input (bytewise) array into a wordwise array.
130	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
131	 */
132	memset(words, '\0', sizeof words);
133	for (i = 0; i < NS_IN6ADDRSZ; i++)
134		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
135	best.base = -1;
136	best.len = 0;
137	cur.base = -1;
138	cur.len = 0;
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 && (best.len == 6 ||
177		    (best.len == 7 && words[7] != 0x0001) ||
178		    (best.len == 5 && words[5] == 0xffff))) {
179			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
180				return (NULL);
181			tp += strlen(tp);
182			break;
183		}
184		tp += SPRINTF((tp, "%x", words[i]));
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
203