1/* Copyright (c) 1996 by Internet Software Consortium.
2 *
3 * Permission to use, copy, modify, and distribute this software for any
4 * purpose with or without fee is hereby granted, provided that the above
5 * copyright notice and this permission notice appear in all copies.
6 *
7 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
8 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
9 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
10 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
11 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
12 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
13 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
14 * SOFTWARE.
15 */
16
17#if defined(LIBC_SCCS) && !defined(lint)
18static char rcsid[] = "$Id: inet_ntop.c,v 1.1.1.1 2008/10/15 03:28:56 james26_jang Exp $";
19#endif /* LIBC_SCCS and not lint */
20
21#include <sys/param.h>
22#include <sys/types.h>
23#include <sys/socket.h>
24#include <netinet/in.h>
25#include <arpa/inet.h>
26#include <arpa/nameser.h>
27#include <string.h>
28#include <errno.h>
29#include <stdio.h>
30
31#include <linux/in6.h>
32#define IN6ADDRSZ sizeof(struct in6_addr)
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	size_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, more or less like inet_ntoa()
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[sizeof(struct in6_addr) / 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 < IN6ADDRSZ; i++)
134		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
135	best.base = -1;
136	cur.base = -1;
137	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
138		if (words[i] == 0) {
139			if (cur.base == -1)
140				cur.base = i, cur.len = 1;
141			else
142				cur.len++;
143		} else {
144			if (cur.base != -1) {
145				if (best.base == -1 || cur.len > best.len)
146					best = cur;
147				cur.base = -1;
148			}
149		}
150	}
151	if (cur.base != -1) {
152		if (best.base == -1 || cur.len > best.len)
153			best = cur;
154	}
155	if (best.base != -1 && best.len < 2)
156		best.base = -1;
157
158	/*
159	 * Format the result.
160	 */
161	tp = tmp;
162	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
163		/* Are we inside the best run of 0x00's? */
164		if (best.base != -1 && i >= best.base &&
165		    i < (best.base + best.len)) {
166			if (i == best.base)
167				*tp++ = ':';
168			continue;
169		}
170		/* Are we following an initial run of 0x00s or any real hex? */
171		if (i != 0)
172			*tp++ = ':';
173		/* Is this address an encapsulated IPv4? */
174		if (i == 6 && best.base == 0 &&
175		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
176			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
177				return (NULL);
178			tp += strlen(tp);
179			break;
180		}
181		tp += SPRINTF((tp, "%x", words[i]));
182	}
183	/* Was it a trailing run of 0x00's? */
184	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / 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