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