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