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#include <sys/socket.h>
27#include <netinet/in.h>
28#include <string.h>
29#include <errno.h>
30#include <stdio.h>
31
32#ifndef IN6ADDRSZ
33#define IN6ADDRSZ   16   /* IPv6 T_AAAA */
34#endif
35
36#ifndef INT16SZ
37#define INT16SZ     2    /* for systems without 16-bit ints */
38#endif
39
40/*
41 * WARNING: Don't even consider trying to compile this on a system where
42 * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
43 */
44
45static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
46static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
47
48/* char *
49 * inet_ntop(af, src, dst, size)
50 *	convert a network format address to presentation format.
51 * return:
52 *	pointer to presentation format address (`dst'), or NULL (see errno).
53 * author:
54 *	Paul Vixie, 1996.
55 */
56const char *
57inet_ntop(int af, const void *src, char *dst, size_t size)
58{
59	switch (af) {
60	case AF_INET:
61		return (inet_ntop4(src, dst, size));
62	case AF_INET6:
63		return (inet_ntop6(src, dst, size));
64	default:
65		errno = EAFNOSUPPORT;
66		return (NULL);
67	}
68	/* NOTREACHED */
69}
70
71/* const char *
72 * inet_ntop4(src, dst, size)
73 *	format an IPv4 address, more or less like inet_ntoa()
74 * return:
75 *	`dst' (as a const)
76 * notes:
77 *	(1) uses no statics
78 *	(2) takes a u_char* not an in_addr as input
79 * author:
80 *	Paul Vixie, 1996.
81 */
82static const char *
83inet_ntop4(const u_char *src, char *dst, size_t size)
84{
85	static const char fmt[] = "%u.%u.%u.%u";
86	char tmp[sizeof "255.255.255.255"];
87	int l;
88
89	l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
90	if (l <= 0 || l >= (int)size) {
91		errno = ENOSPC;
92		return (NULL);
93	}
94	strlcpy(dst, tmp, size);
95	return (dst);
96}
97
98/* const char *
99 * inet_ntop6(src, dst, size)
100 *	convert IPv6 binary address into presentation (printable) format
101 * author:
102 *	Paul Vixie, 1996.
103 */
104static const char *
105inet_ntop6(const u_char *src, char *dst, size_t size)
106{
107	/*
108	 * Note that int32_t and int16_t need only be "at least" large enough
109	 * to contain a value of the specified size.  On some systems, like
110	 * Crays, there is no such thing as an integer variable with 16 bits.
111	 * Keep this in mind if you think this function should have been coded
112	 * to use pointer overlays.  All the world's not a VAX.
113	 */
114	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
115	char *tp, *ep;
116	struct { int base, len; } best, cur;
117	u_int words[IN6ADDRSZ / INT16SZ];
118	int i;
119	int advance;
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 < IN6ADDRSZ; i++)
128		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
129	best.base = -1;
130	cur.base = -1;
131	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
132		if (words[i] == 0) {
133			if (cur.base == -1)
134				cur.base = i, cur.len = 1;
135			else
136				cur.len++;
137		} else {
138			if (cur.base != -1) {
139				if (best.base == -1 || cur.len > best.len)
140					best = cur;
141				cur.base = -1;
142			}
143		}
144	}
145	if (cur.base != -1) {
146		if (best.base == -1 || cur.len > best.len)
147			best = cur;
148	}
149	if (best.base != -1 && best.len < 2)
150		best.base = -1;
151
152	/*
153	 * Format the result.
154	 */
155	tp = tmp;
156	ep = tmp + sizeof(tmp);
157	for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
158		/* Are we inside the best run of 0x00's? */
159		if (best.base != -1 && i >= best.base &&
160		    i < (best.base + best.len)) {
161			if (i == best.base) {
162				if (tp + 1 >= ep)
163					return (NULL);
164				*tp++ = ':';
165			}
166			continue;
167		}
168		/* Are we following an initial run of 0x00s or any real hex? */
169		if (i != 0) {
170			if (tp + 1 >= ep)
171				return (NULL);
172			*tp++ = ':';
173		}
174		/* Is this address an encapsulated IPv4? */
175		if (i == 6 && best.base == 0 &&
176		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
177			if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
178				return (NULL);
179			tp += strlen(tp);
180			break;
181		}
182		advance = snprintf(tp, ep - tp, "%x", words[i]);
183		if (advance <= 0 || advance >= ep - tp)
184			return (NULL);
185		tp += advance;
186	}
187	/* Was it a trailing run of 0x00's? */
188	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
189		if (tp + 1 >= ep)
190			return (NULL);
191		*tp++ = ':';
192	}
193	if (tp + 1 >= ep)
194		return (NULL);
195	*tp++ = '\0';
196
197	/*
198	 * Check for overflow, copy, and we're done.
199	 */
200	if ((size_t)(tp - tmp) > size) {
201		errno = ENOSPC;
202		return (NULL);
203	}
204	strlcpy(dst, tmp, size);
205	return (dst);
206}
207
208#endif /* !HAVE_INET_NTOP */
209