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 "port_before.h"
23
24#include <sys/param.h>
25#include <sys/types.h>
26#include <sys/socket.h>
27
28#include <netinet/in.h>
29#include <arpa/inet.h>
30#include <arpa/nameser.h>
31
32#include <errno.h>
33#include <stdio.h>
34#include <string.h>
35
36#include "port_after.h"
37
38#ifdef SPRINTF_CHAR
39# define SPRINTF(x) strlen(sprintf/**/x)
40#else
41# define SPRINTF(x) ((size_t)sprintf x)
42#endif
43
44/*%
45 * WARNING: Don't even consider trying to compile this on a system where
46 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
47 */
48
49static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
50static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
51
52/* char *
53 * inet_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 *
61inet_ntop(af, src, dst, size)
62	int af;
63	const void *src;
64	char *dst;
65	socklen_t size;
66{
67	switch (af) {
68	case AF_INET:
69		return (inet_ntop4(src, dst, size));
70	case AF_INET6:
71		return (inet_ntop6(src, dst, size));
72	default:
73		errno = EAFNOSUPPORT;
74		return (NULL);
75	}
76	/* NOTREACHED */
77}
78
79/* const char *
80 * inet_ntop4(src, dst, size)
81 *	format an IPv4 address
82 * return:
83 *	`dst' (as a const)
84 * notes:
85 *	(1) uses no statics
86 *	(2) takes a u_char* not an in_addr as input
87 * author:
88 *	Paul Vixie, 1996.
89 */
90static const char *
91inet_ntop4(src, dst, size)
92	const u_char *src;
93	char *dst;
94	size_t size;
95{
96	static const char fmt[] = "%u.%u.%u.%u";
97	char tmp[sizeof "255.255.255.255"];
98
99	if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
100		errno = ENOSPC;
101		return (NULL);
102	}
103	strcpy(dst, tmp);
104	return (dst);
105}
106
107/* const char *
108 * inet_ntop6(src, dst, size)
109 *	convert IPv6 binary address into presentation (printable) format
110 * author:
111 *	Paul Vixie, 1996.
112 */
113static const char *
114inet_ntop6(src, dst, size)
115	const u_char *src;
116	char *dst;
117	size_t size;
118{
119	/*
120	 * Note that int32_t and int16_t need only be "at least" large enough
121	 * to contain a value of the specified size.  On some systems, like
122	 * Crays, there is no such thing as an integer variable with 16 bits.
123	 * Keep this in mind if you think this function should have been coded
124	 * to use pointer overlays.  All the world's not a VAX.
125	 */
126	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
127	struct { int base, len; } best, cur;
128	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
129	int i;
130
131	/*
132	 * Preprocess:
133	 *	Copy the input (bytewise) array into a wordwise array.
134	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
135	 */
136	memset(words, '\0', sizeof words);
137	for (i = 0; i < NS_IN6ADDRSZ; i++)
138		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
139	best.base = -1;
140	best.len = 0;
141	cur.base = -1;
142	cur.len = 0;
143	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
144		if (words[i] == 0) {
145			if (cur.base == -1)
146				cur.base = i, cur.len = 1;
147			else
148				cur.len++;
149		} else {
150			if (cur.base != -1) {
151				if (best.base == -1 || cur.len > best.len)
152					best = cur;
153				cur.base = -1;
154			}
155		}
156	}
157	if (cur.base != -1) {
158		if (best.base == -1 || cur.len > best.len)
159			best = cur;
160	}
161	if (best.base != -1 && best.len < 2)
162		best.base = -1;
163
164	/*
165	 * Format the result.
166	 */
167	tp = tmp;
168	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
169		/* Are we inside the best run of 0x00's? */
170		if (best.base != -1 && i >= best.base &&
171		    i < (best.base + best.len)) {
172			if (i == best.base)
173				*tp++ = ':';
174			continue;
175		}
176		/* Are we following an initial run of 0x00s or any real hex? */
177		if (i != 0)
178			*tp++ = ':';
179		/* Is this address an encapsulated IPv4? */
180		if (i == 6 && best.base == 0 && (best.len == 6 ||
181		    (best.len == 7 && words[7] != 0x0001) ||
182		    (best.len == 5 && words[5] == 0xffff))) {
183			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
184				return (NULL);
185			tp += strlen(tp);
186			break;
187		}
188		tp += SPRINTF((tp, "%x", words[i]));
189	}
190	/* Was it a trailing run of 0x00's? */
191	if (best.base != -1 && (best.base + best.len) ==
192	    (NS_IN6ADDRSZ / NS_INT16SZ))
193		*tp++ = ':';
194	*tp++ = '\0';
195
196	/*
197	 * Check for overflow, copy, and we're done.
198	 */
199	if ((size_t)(tp - tmp) > size) {
200		errno = ENOSPC;
201		return (NULL);
202	}
203	strcpy(dst, tmp);
204	return (dst);
205}
206
207#undef inet_ntop
208#pragma weak inet_ntop = __inet_ntop
209