1/*	$NetBSD: inet_ntop.c,v 1.1.1.4 2009/04/12 16:35:45 christos Exp $	*/
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#include <sys/cdefs.h>
21#if defined(LIBC_SCCS) && !defined(lint)
22#if 0
23static const char rcsid[] = "Id: inet_ntop.c,v 1.5 2005/11/03 22:59:52 marka Exp";
24#else
25__RCSID("$NetBSD: inet_ntop.c,v 1.7 2008/09/11 15:40:43 christos Exp $");
26#endif
27#endif /* LIBC_SCCS and not lint */
28
29#include "port_before.h"
30
31#include "namespace.h"
32#include <sys/param.h>
33#include <sys/types.h>
34#include <sys/socket.h>
35
36#include <netinet/in.h>
37#include <arpa/inet.h>
38#include <arpa/nameser.h>
39
40#include <assert.h>
41#include <errno.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45
46#include "port_after.h"
47
48#ifdef __weak_alias
49__weak_alias(inet_ntop,_inet_ntop)
50#endif
51
52/*%
53 * WARNING: Don't even consider trying to compile this on a system where
54 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
55 */
56
57static const char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
58static const char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
59
60/* char *
61 * inet_ntop(af, src, dst, size)
62 *	convert a network format address to presentation format.
63 * return:
64 *	pointer to presentation format address (`dst'), or NULL (see errno).
65 * author:
66 *	Paul Vixie, 1996.
67 */
68const char *
69inet_ntop(af, src, dst, size)
70	int af;
71	const void *src;
72	char *dst;
73	socklen_t size;
74{
75
76	_DIAGASSERT(src != NULL);
77	_DIAGASSERT(dst != NULL);
78
79	switch (af) {
80	case AF_INET:
81		return (inet_ntop4(src, dst, size));
82	case AF_INET6:
83		return (inet_ntop6(src, dst, size));
84	default:
85		errno = EAFNOSUPPORT;
86		return (NULL);
87	}
88	/* NOTREACHED */
89}
90
91/* const char *
92 * inet_ntop4(src, dst, size)
93 *	format an IPv4 address, more or less like inet_ntoa()
94 * return:
95 *	`dst' (as a const)
96 * notes:
97 *	(1) uses no statics
98 *	(2) takes a u_char* not an in_addr as input
99 * author:
100 *	Paul Vixie, 1996.
101 */
102static const char *
103inet_ntop4(src, dst, size)
104	const u_char *src;
105	char *dst;
106	socklen_t size;
107{
108	char tmp[sizeof "255.255.255.255"];
109	int l;
110
111	_DIAGASSERT(src != NULL);
112	_DIAGASSERT(dst != NULL);
113
114	l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u",
115	    src[0], src[1], src[2], src[3]);
116	if (l <= 0 || (socklen_t) l >= size) {
117		errno = ENOSPC;
118		return (NULL);
119	}
120	strlcpy(dst, tmp, size);
121	return (dst);
122}
123
124/* const char *
125 * inet_ntop6(src, dst, size)
126 *	convert IPv6 binary address into presentation (printable) format
127 * author:
128 *	Paul Vixie, 1996.
129 */
130static const char *
131inet_ntop6(src, dst, size)
132	const u_char *src;
133	char *dst;
134	socklen_t size;
135{
136	/*
137	 * Note that int32_t and int16_t need only be "at least" large enough
138	 * to contain a value of the specified size.  On some systems, like
139	 * Crays, there is no such thing as an integer variable with 16 bits.
140	 * Keep this in mind if you think this function should have been coded
141	 * to use pointer overlays.  All the world's not a VAX.
142	 */
143	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
144	char *tp, *ep;
145	struct { int base, len; } best, cur;
146	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
147	int i;
148	int advance;
149
150	_DIAGASSERT(src != NULL);
151	_DIAGASSERT(dst != NULL);
152
153	/*
154	 * Preprocess:
155	 *	Copy the input (bytewise) array into a wordwise array.
156	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
157	 */
158	memset(words, '\0', sizeof words);
159	for (i = 0; i < NS_IN6ADDRSZ; i++)
160		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
161	best.base = -1;
162	best.len = 0;
163	cur.base = -1;
164	cur.len = 0;
165	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
166		if (words[i] == 0) {
167			if (cur.base == -1)
168				cur.base = i, cur.len = 1;
169			else
170				cur.len++;
171		} else {
172			if (cur.base != -1) {
173				if (best.base == -1 || cur.len > best.len)
174					best = cur;
175				cur.base = -1;
176			}
177		}
178	}
179	if (cur.base != -1) {
180		if (best.base == -1 || cur.len > best.len)
181			best = cur;
182	}
183	if (best.base != -1 && best.len < 2)
184		best.base = -1;
185
186	/*
187	 * Format the result.
188	 */
189	tp = tmp;
190	ep = tmp + sizeof(tmp);
191	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
192		/* Are we inside the best run of 0x00's? */
193		if (best.base != -1 && i >= best.base &&
194		    i < (best.base + best.len)) {
195			if (i == best.base)
196				*tp++ = ':';
197			continue;
198		}
199		/* Are we following an initial run of 0x00s or any real hex? */
200		if (i != 0) {
201			if (tp + 1 >= ep)
202				return (NULL);
203			*tp++ = ':';
204		}
205		/* Is this address an encapsulated IPv4? */
206		if (i == 6 && best.base == 0 &&
207		    (best.len == 6 ||
208		    (best.len == 7 && words[7] != 0x0001) ||
209		    (best.len == 5 && words[5] == 0xffff))) {
210			if (!inet_ntop4(src+12, tp, (socklen_t)(ep - tp)))
211				return (NULL);
212			tp += strlen(tp);
213			break;
214		}
215		advance = snprintf(tp, (size_t)(ep - tp), "%x", words[i]);
216		if (advance <= 0 || advance >= ep - tp)
217			return (NULL);
218		tp += advance;
219	}
220	/* Was it a trailing run of 0x00's? */
221	if (best.base != -1 && (best.base + best.len) ==
222	    (NS_IN6ADDRSZ / NS_INT16SZ)) {
223		if (tp + 1 >= ep)
224			return (NULL);
225		*tp++ = ':';
226	}
227	if (tp + 1 >= ep)
228		return (NULL);
229	*tp++ = '\0';
230
231	/*
232	 * Check for overflow, copy, and we're done.
233	 */
234	if ((size_t)(tp - tmp) > size) {
235		errno = ENOSPC;
236		return (NULL);
237	}
238	strlcpy(dst, tmp, size);
239	return (dst);
240}
241
242/*! \file */
243