1/* From openssh 4.3p2 compat/inet_ntop.c */
2/* Copyright (c) 1996 by Internet Software Consortium.
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
15 * SOFTWARE.
16 */
17
18/* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */
19
20#include <config.h>
21
22#ifndef HAVE_INET_NTOP
23
24#include <sys/param.h>
25#include <sys/types.h>
26#ifdef HAVE_SYS_SOCKET_H
27#include <sys/socket.h>
28#endif
29#ifdef HAVE_NETINET_IN_H
30#include <netinet/in.h>
31#endif
32#include <string.h>
33#include <errno.h>
34#include <stdio.h>
35
36#ifndef IN6ADDRSZ
37#define IN6ADDRSZ   16   /* IPv6 T_AAAA */
38#endif
39
40#ifndef INT16SZ
41#define INT16SZ     2    /* for systems without 16-bit ints */
42#endif
43
44/*
45 * WARNING: Don't even consider trying to compile this on a system where
46 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
47 */
48
49static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
50static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
51
52/* char *
53 * inet_ntop(af, src, dst, size)
54 *	convert a network format address to presentation format.
55 * return:
56 *	pointer to presentation format address (`dst'), or NULL (see errno).
57 * author:
58 *	Paul Vixie, 1996.
59 */
60const char *
61inet_ntop(int af, const void *src, char *dst, size_t size)
62{
63	switch (af) {
64	case AF_INET:
65		return (inet_ntop4(src, dst, size));
66	case AF_INET6:
67		return (inet_ntop6(src, dst, size));
68	default:
69#ifdef EAFNOSUPPORT
70		errno = EAFNOSUPPORT;
71#else
72		errno = ENOSYS;
73#endif
74		return (NULL);
75	}
76	/* NOTREACHED */
77}
78
79/* const char *
80 * inet_ntop4(src, dst, size)
81 *	format an IPv4 address, more or less like inet_ntoa()
82 * return:
83 *	`dst' (as a const)
84 * notes:
85 *	(1) uses no statics
86 *	(2) takes a u_char* not an in_addr as input
87 * author:
88 *	Paul Vixie, 1996.
89 */
90static const char *
91inet_ntop4(const u_char *src, char *dst, size_t size)
92{
93	static const char fmt[] = "%u.%u.%u.%u";
94	char tmp[sizeof "255.255.255.255"];
95	int l;
96
97	l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
98	if (l <= 0 || l >= (int)size) {
99		errno = ENOSPC;
100		return (NULL);
101	}
102	strlcpy(dst, tmp, size);
103	return (dst);
104}
105
106/* const char *
107 * inet_ntop6(src, dst, size)
108 *	convert IPv6 binary address into presentation (printable) format
109 * author:
110 *	Paul Vixie, 1996.
111 */
112static const char *
113inet_ntop6(const u_char *src, char *dst, size_t size)
114{
115	/*
116	 * Note that int32_t and int16_t need only be "at least" large enough
117	 * to contain a value of the specified size.  On some systems, like
118	 * Crays, there is no such thing as an integer variable with 16 bits.
119	 * Keep this in mind if you think this function should have been coded
120	 * to use pointer overlays.  All the world's not a VAX.
121	 */
122	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
123	char *tp, *ep;
124	struct { int base, len; } best, cur;
125	u_int words[IN6ADDRSZ / INT16SZ];
126	int i;
127	int advance;
128
129	/*
130	 * Preprocess:
131	 *	Copy the input (bytewise) array into a wordwise array.
132	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
133	 */
134	memset(words, '\0', sizeof words);
135	for (i = 0; i < IN6ADDRSZ; i++)
136		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
137	best.base = -1;
138	best.len = 0;
139	cur.base = -1;
140	cur.len = 0;
141	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
142		if (words[i] == 0) {
143			if (cur.base == -1)
144				cur.base = i, cur.len = 1;
145			else
146				cur.len++;
147		} else {
148			if (cur.base != -1) {
149				if (best.base == -1 || cur.len > best.len)
150					best = cur;
151				cur.base = -1;
152			}
153		}
154	}
155	if (cur.base != -1) {
156		if (best.base == -1 || cur.len > best.len)
157			best = cur;
158	}
159	if (best.base != -1 && best.len < 2)
160		best.base = -1;
161
162	/*
163	 * Format the result.
164	 */
165	tp = tmp;
166	ep = tmp + sizeof(tmp);
167	for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
168		/* Are we inside the best run of 0x00's? */
169		if (best.base != -1 && i >= best.base &&
170		    i < (best.base + best.len)) {
171			if (i == best.base) {
172				if (tp + 1 >= ep)
173					return (NULL);
174				*tp++ = ':';
175			}
176			continue;
177		}
178		/* Are we following an initial run of 0x00s or any real hex? */
179		if (i != 0) {
180			if (tp + 1 >= ep)
181				return (NULL);
182			*tp++ = ':';
183		}
184		/* Is this address an encapsulated IPv4? */
185		if (i == 6 && best.base == 0 &&
186		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
187			if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
188				return (NULL);
189			tp += strlen(tp);
190			break;
191		}
192		advance = snprintf(tp, ep - tp, "%x", words[i]);
193		if (advance <= 0 || advance >= ep - tp)
194			return (NULL);
195		tp += advance;
196	}
197	/* Was it a trailing run of 0x00's? */
198	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
199		if (tp + 1 >= ep)
200			return (NULL);
201		*tp++ = ':';
202	}
203	if (tp + 1 >= ep)
204		return (NULL);
205	*tp++ = '\0';
206
207	/*
208	 * Check for overflow, copy, and we're done.
209	 */
210	if ((size_t)(tp - tmp) > size) {
211		errno = ENOSPC;
212		return (NULL);
213	}
214	strlcpy(dst, tmp, size);
215	return (dst);
216}
217
218#endif /* !HAVE_INET_NTOP */
219