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