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 $";
20#endif /* LIBC_SCCS and not lint */
21#include <sys/cdefs.h>
22__FBSDID("$FreeBSD$");
23
24#include "port_before.h"
25
26#include <sys/param.h>
27#include <sys/socket.h>
28
29#include <netinet/in.h>
30#include <arpa/inet.h>
31#include <arpa/nameser.h>
32
33#include <errno.h>
34#include <stdio.h>
35#include <string.h>
36
37#include "port_after.h"
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 u_char *src, char *dst, socklen_t size);
45static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
46
47/* const char *
48 * inet_ntop(af, src, dst, size)
49 *	convert a network format address to presentation format.
50 * return:
51 *	pointer to presentation format address (`dst'), or NULL (see errno).
52 * author:
53 *	Paul Vixie, 1996.
54 */
55const char *
56inet_ntop(int af, const void * __restrict src, char * __restrict dst,
57    socklen_t size)
58{
59	switch (af) {
60	case AF_INET:
61		return (inet_ntop4(src, dst, size));
62	case AF_INET6:
63		return (inet_ntop6(src, dst, size));
64	default:
65		errno = EAFNOSUPPORT;
66		return (NULL);
67	}
68	/* NOTREACHED */
69}
70
71/* const char *
72 * inet_ntop4(src, dst, size)
73 *	format an IPv4 address
74 * return:
75 *	`dst' (as a const)
76 * notes:
77 *	(1) uses no statics
78 *	(2) takes a u_char* not an in_addr as input
79 * author:
80 *	Paul Vixie, 1996.
81 */
82static const char *
83inet_ntop4(const u_char *src, char *dst, socklen_t size)
84{
85	static const char fmt[] = "%u.%u.%u.%u";
86	char tmp[sizeof "255.255.255.255"];
87	int l;
88
89	l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
90	if (l <= 0 || (socklen_t) l >= size) {
91		errno = ENOSPC;
92		return (NULL);
93	}
94	strlcpy(dst, tmp, size);
95	return (dst);
96}
97
98/* const char *
99 * inet_ntop6(src, dst, size)
100 *	convert IPv6 binary address into presentation (printable) format
101 * author:
102 *	Paul Vixie, 1996.
103 */
104static const char *
105inet_ntop6(const u_char *src, char *dst, socklen_t size)
106{
107	/*
108	 * Note that int32_t and int16_t need only be "at least" large enough
109	 * to contain a value of the specified size.  On some systems, like
110	 * Crays, there is no such thing as an integer variable with 16 bits.
111	 * Keep this in mind if you think this function should have been coded
112	 * to use pointer overlays.  All the world's not a VAX.
113	 */
114	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
115	struct { int base, len; } best, cur;
116	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
117	int i;
118
119	/*
120	 * Preprocess:
121	 *	Copy the input (bytewise) array into a wordwise array.
122	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
123	 */
124	memset(words, '\0', sizeof words);
125	for (i = 0; i < NS_IN6ADDRSZ; i++)
126		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
127	best.base = -1;
128	best.len = 0;
129	cur.base = -1;
130	cur.len = 0;
131	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
132		if (words[i] == 0) {
133			if (cur.base == -1)
134				cur.base = i, cur.len = 1;
135			else
136				cur.len++;
137		} else {
138			if (cur.base != -1) {
139				if (best.base == -1 || cur.len > best.len)
140					best = cur;
141				cur.base = -1;
142			}
143		}
144	}
145	if (cur.base != -1) {
146		if (best.base == -1 || cur.len > best.len)
147			best = cur;
148	}
149	if (best.base != -1 && best.len < 2)
150		best.base = -1;
151
152	/*
153	 * Format the result.
154	 */
155	tp = tmp;
156	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
157		/* Are we inside the best run of 0x00's? */
158		if (best.base != -1 && i >= best.base &&
159		    i < (best.base + best.len)) {
160			if (i == best.base)
161				*tp++ = ':';
162			continue;
163		}
164		/* Are we following an initial run of 0x00s or any real hex? */
165		if (i != 0)
166			*tp++ = ':';
167		/* Is this address an encapsulated IPv4? */
168		if (i == 6 && best.base == 0 && (best.len == 6 ||
169		    (best.len == 7 && words[7] != 0x0001) ||
170		    (best.len == 5 && words[5] == 0xffff))) {
171			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp))) {
172				errno = ENOSPC;
173				return (NULL);
174			}
175			tp += strlen(tp);
176			break;
177		}
178		tp += sprintf(tp, "%x", words[i]);
179	}
180	/* Was it a trailing run of 0x00's? */
181	if (best.base != -1 && (best.base + best.len) ==
182	    (NS_IN6ADDRSZ / NS_INT16SZ))
183		*tp++ = ':';
184	*tp++ = '\0';
185
186	/*
187	 * Check for overflow, copy, and we're done.
188	 */
189	if ((socklen_t)(tp - tmp) > size) {
190		errno = ENOSPC;
191		return (NULL);
192	}
193	strcpy(dst, tmp);
194	return (dst);
195}
196
197/*
198 * Weak aliases for applications that use certain private entry points,
199 * and fail to include <arpa/inet.h>.
200 */
201#undef inet_ntop
202__weak_reference(__inet_ntop, inet_ntop);
203
204/*! \file */
205