1/*	$NetBSD$	*/
2
3/*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996-1999 by Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#if defined(LIBC_SCCS) && !defined(lint)
21static const char rcsid[] = "Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp ";
22#endif /* LIBC_SCCS and not lint */
23
24#include "port_before.h"
25
26#include <sys/param.h>
27#include <sys/types.h>
28#include <sys/socket.h>
29
30#include <netinet/in.h>
31#include <arpa/inet.h>
32#include <arpa/nameser.h>
33
34#include <errno.h>
35#include <stdio.h>
36#include <string.h>
37
38#include "port_after.h"
39
40#ifdef SPRINTF_CHAR
41# define SPRINTF(x) strlen(sprintf/**/x)
42#else
43# define SPRINTF(x) ((size_t)sprintf x)
44#endif
45
46/*%
47 * WARNING: Don't even consider trying to compile this on a system where
48 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
49 */
50
51static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
52static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
53
54/* char *
55 * inet_ntop(af, src, dst, size)
56 *	convert a network format address to presentation format.
57 * return:
58 *	pointer to presentation format address (`dst'), or NULL (see errno).
59 * author:
60 *	Paul Vixie, 1996.
61 */
62const char *
63inet_ntop(af, src, dst, size)
64	int af;
65	const void *src;
66	char *dst;
67	size_t size;
68{
69	switch (af) {
70	case AF_INET:
71		return (inet_ntop4(src, dst, size));
72	case AF_INET6:
73		return (inet_ntop6(src, dst, size));
74	default:
75		errno = EAFNOSUPPORT;
76		return (NULL);
77	}
78	/* NOTREACHED */
79}
80
81/* const char *
82 * inet_ntop4(src, dst, size)
83 *	format an IPv4 address
84 * return:
85 *	`dst' (as a const)
86 * notes:
87 *	(1) uses no statics
88 *	(2) takes a u_char* not an in_addr as input
89 * author:
90 *	Paul Vixie, 1996.
91 */
92static const char *
93inet_ntop4(src, dst, size)
94	const u_char *src;
95	char *dst;
96	size_t size;
97{
98	static const char fmt[] = "%u.%u.%u.%u";
99	char tmp[sizeof "255.255.255.255"];
100
101	if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
102		errno = ENOSPC;
103		return (NULL);
104	}
105	strcpy(dst, tmp);
106	return (dst);
107}
108
109/* const char *
110 * inet_ntop6(src, dst, size)
111 *	convert IPv6 binary address into presentation (printable) format
112 * author:
113 *	Paul Vixie, 1996.
114 */
115static const char *
116inet_ntop6(src, dst, size)
117	const u_char *src;
118	char *dst;
119	size_t size;
120{
121	/*
122	 * Note that int32_t and int16_t need only be "at least" large enough
123	 * to contain a value of the specified size.  On some systems, like
124	 * Crays, there is no such thing as an integer variable with 16 bits.
125	 * Keep this in mind if you think this function should have been coded
126	 * to use pointer overlays.  All the world's not a VAX.
127	 */
128	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
129	struct { int base, len; } best, cur;
130	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
131	int i;
132
133	/*
134	 * Preprocess:
135	 *	Copy the input (bytewise) array into a wordwise array.
136	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
137	 */
138	memset(words, '\0', sizeof words);
139	for (i = 0; i < NS_IN6ADDRSZ; i++)
140		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
141	best.base = -1;
142	best.len = 0;
143	cur.base = -1;
144	cur.len = 0;
145	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
146		if (words[i] == 0) {
147			if (cur.base == -1)
148				cur.base = i, cur.len = 1;
149			else
150				cur.len++;
151		} else {
152			if (cur.base != -1) {
153				if (best.base == -1 || cur.len > best.len)
154					best = cur;
155				cur.base = -1;
156			}
157		}
158	}
159	if (cur.base != -1) {
160		if (best.base == -1 || cur.len > best.len)
161			best = cur;
162	}
163	if (best.base != -1 && best.len < 2)
164		best.base = -1;
165
166	/*
167	 * Format the result.
168	 */
169	tp = tmp;
170	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
171		/* Are we inside the best run of 0x00's? */
172		if (best.base != -1 && i >= best.base &&
173		    i < (best.base + best.len)) {
174			if (i == best.base)
175				*tp++ = ':';
176			continue;
177		}
178		/* Are we following an initial run of 0x00s or any real hex? */
179		if (i != 0)
180			*tp++ = ':';
181		/* Is this address an encapsulated IPv4? */
182		if (i == 6 && best.base == 0 && (best.len == 6 ||
183		    (best.len == 7 && words[7] != 0x0001) ||
184		    (best.len == 5 && words[5] == 0xffff))) {
185			if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
186				return (NULL);
187			tp += strlen(tp);
188			break;
189		}
190		tp += SPRINTF((tp, "%x", words[i]));
191	}
192	/* Was it a trailing run of 0x00's? */
193	if (best.base != -1 && (best.base + best.len) ==
194	    (NS_IN6ADDRSZ / NS_INT16SZ))
195		*tp++ = ':';
196	*tp++ = '\0';
197
198	/*
199	 * Check for overflow, copy, and we're done.
200	 */
201	if ((size_t)(tp - tmp) > size) {
202		errno = ENOSPC;
203		return (NULL);
204	}
205	strcpy(dst, tmp);
206	return (dst);
207}
208
209/*! \file */
210