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#include <sys/param.h>
19#include <sys/socket.h>
20#include <sys/systm.h>
21
22#include <netinet/in.h>
23
24/*%
25 * WARNING: Don't even consider trying to compile this on a system where
26 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
27 */
28
29static char	*inet_ntop4(const u_char *src, char *dst, socklen_t size);
30static char	*inet_ntop6(const u_char *src, char *dst, socklen_t size);
31
32/* char *
33 * inet_ntop(af, src, dst, size)
34 *	convert a network format address to presentation format.
35 * return:
36 *	pointer to presentation format address (`dst'), or NULL (see errno).
37 * author:
38 *	Paul Vixie, 1996.
39 */
40char *
41inet_ntop(int af, const void *src, char *dst, socklen_t size)
42{
43	switch (af) {
44	case AF_INET:
45		return (inet_ntop4(src, dst, size));
46	case AF_INET6:
47		return (inet_ntop6(src, dst, size));
48	default:
49		return (NULL);
50	}
51	/* NOTREACHED */
52}
53
54/* const char *
55 * inet_ntop4(src, dst, size)
56 *	format an IPv4 address
57 * return:
58 *	`dst' (as a const)
59 * notes:
60 *	(1) uses no statics
61 *	(2) takes a u_char* not an in_addr as input
62 * author:
63 *	Paul Vixie, 1996.
64 */
65static char *
66inet_ntop4(const u_char *src, char *dst, socklen_t size)
67{
68	static const char fmt[] = "%u.%u.%u.%u";
69	char tmp[sizeof "255.255.255.255"];
70	int l;
71
72	l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
73	if (l <= 0 || (socklen_t) l >= size) {
74		return (NULL);
75	}
76	strlcpy(dst, tmp, size);
77	return (dst);
78}
79
80/* const char *
81 * inet_ntop6(src, dst, size)
82 *	convert IPv6 binary address into presentation (printable) format
83 * author:
84 *	Paul Vixie, 1996.
85 */
86static char *
87inet_ntop6(const u_char *src, char *dst, socklen_t size)
88{
89	/*
90	 * Note that int32_t and int16_t need only be "at least" large enough
91	 * to contain a value of the specified size.  On some systems, like
92	 * Crays, there is no such thing as an integer variable with 16 bits.
93	 * Keep this in mind if you think this function should have been coded
94	 * to use pointer overlays.  All the world's not a VAX.
95	 */
96	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
97	struct { int base, len; } best, cur;
98#define NS_IN6ADDRSZ	16
99#define NS_INT16SZ	2
100	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
101	int i;
102
103	/*
104	 * Preprocess:
105	 *	Copy the input (bytewise) array into a wordwise array.
106	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
107	 */
108	memset(words, '\0', sizeof words);
109	for (i = 0; i < NS_IN6ADDRSZ; i++)
110		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
111	best.base = -1;
112	best.len = 0;
113	cur.base = -1;
114	cur.len = 0;
115	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
116		if (words[i] == 0) {
117			if (cur.base == -1)
118				cur.base = i, cur.len = 1;
119			else
120				cur.len++;
121		} else {
122			if (cur.base != -1) {
123				if (best.base == -1 || cur.len > best.len)
124					best = cur;
125				cur.base = -1;
126			}
127		}
128	}
129	if (cur.base != -1) {
130		if (best.base == -1 || cur.len > best.len)
131			best = cur;
132	}
133	if (best.base != -1 && best.len < 2)
134		best.base = -1;
135
136	/*
137	 * Format the result.
138	 */
139	tp = tmp;
140	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
141		/* Are we inside the best run of 0x00's? */
142		if (best.base != -1 && i >= best.base &&
143		    i < (best.base + best.len)) {
144			if (i == best.base)
145				*tp++ = ':';
146			continue;
147		}
148		/* Are we following an initial run of 0x00s or any real hex? */
149		if (i != 0)
150			*tp++ = ':';
151		/* Is this address an encapsulated IPv4? */
152		if (i == 6 && best.base == 0 && (best.len == 6 ||
153		    (best.len == 7 && words[7] != 0x0001) ||
154		    (best.len == 5 && words[5] == 0xffff))) {
155			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
156				return (NULL);
157			tp += strlen(tp);
158			break;
159		}
160		tp += sprintf(tp, "%x", words[i]);
161	}
162	/* Was it a trailing run of 0x00's? */
163	if (best.base != -1 && (best.base + best.len) ==
164	    (NS_IN6ADDRSZ / NS_INT16SZ))
165		*tp++ = ':';
166	*tp++ = '\0';
167
168	/*
169	 * Check for overflow, copy, and we're done.
170	 */
171	if ((socklen_t)(tp - tmp) > size) {
172		return (NULL);
173	}
174	strcpy(dst, tmp);
175	return (dst);
176}
177
178/*! \file */
179