xref: /freebsd/crypto/openssh/openbsd-compat/inet_ntop.c (revision 74bf4e164ba5851606a27d4feff27717452583e5)
1 /* OPENBSD ORIGINAL: lib/libc/net/inet_ntop.c */
2 
3 /*	$OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $	*/
4 
5 /* Copyright (c) 1996 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
12  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
13  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
14  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
15  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
16  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
17  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
18  * SOFTWARE.
19  */
20 
21 #include "includes.h"
22 
23 #ifndef HAVE_INET_NTOP
24 
25 #if defined(LIBC_SCCS) && !defined(lint)
26 #if 0
27 static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
28 #else
29 static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.5 2002/08/23 16:27:31 itojun Exp $";
30 #endif
31 #endif /* LIBC_SCCS and not lint */
32 
33 #include <sys/param.h>
34 #include <sys/types.h>
35 #include <sys/socket.h>
36 #include <netinet/in.h>
37 #include <arpa/inet.h>
38 #ifndef HAVE_CYGWIN
39 #include <arpa/nameser.h>
40 #endif
41 #include <string.h>
42 #include <errno.h>
43 #include <stdio.h>
44 
45 #ifndef IN6ADDRSZ
46 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */
47 #endif
48 
49 #ifndef INT16SZ
50 #define INT16SZ     2    /* for systems without 16-bit ints */
51 #endif
52 
53 /*
54  * WARNING: Don't even consider trying to compile this on a system where
55  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
56  */
57 
58 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
59 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
60 
61 /* char *
62  * inet_ntop(af, src, dst, size)
63  *	convert a network format address to presentation format.
64  * return:
65  *	pointer to presentation format address (`dst'), or NULL (see errno).
66  * author:
67  *	Paul Vixie, 1996.
68  */
69 const char *
70 inet_ntop(af, src, dst, size)
71 	int af;
72 	const void *src;
73 	char *dst;
74 	size_t size;
75 {
76 	switch (af) {
77 	case AF_INET:
78 		return (inet_ntop4(src, dst, size));
79 	case AF_INET6:
80 		return (inet_ntop6(src, dst, size));
81 	default:
82 		errno = EAFNOSUPPORT;
83 		return (NULL);
84 	}
85 	/* NOTREACHED */
86 }
87 
88 /* const char *
89  * inet_ntop4(src, dst, size)
90  *	format an IPv4 address, more or less like inet_ntoa()
91  * return:
92  *	`dst' (as a const)
93  * notes:
94  *	(1) uses no statics
95  *	(2) takes a u_char* not an in_addr as input
96  * author:
97  *	Paul Vixie, 1996.
98  */
99 static const char *
100 inet_ntop4(src, dst, size)
101 	const u_char *src;
102 	char *dst;
103 	size_t size;
104 {
105 	static const char fmt[] = "%u.%u.%u.%u";
106 	char tmp[sizeof "255.255.255.255"];
107 	int l;
108 
109 	l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
110 	if (l <= 0 || l >= size) {
111 		errno = ENOSPC;
112 		return (NULL);
113 	}
114 	strlcpy(dst, tmp, size);
115 	return (dst);
116 }
117 
118 /* const char *
119  * inet_ntop6(src, dst, size)
120  *	convert IPv6 binary address into presentation (printable) format
121  * author:
122  *	Paul Vixie, 1996.
123  */
124 static const char *
125 inet_ntop6(src, dst, size)
126 	const u_char *src;
127 	char *dst;
128 	size_t size;
129 {
130 	/*
131 	 * Note that int32_t and int16_t need only be "at least" large enough
132 	 * to contain a value of the specified size.  On some systems, like
133 	 * Crays, there is no such thing as an integer variable with 16 bits.
134 	 * Keep this in mind if you think this function should have been coded
135 	 * to use pointer overlays.  All the world's not a VAX.
136 	 */
137 	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
138 	char *tp, *ep;
139 	struct { int base, len; } best, cur;
140 	u_int words[IN6ADDRSZ / INT16SZ];
141 	int i;
142 	int advance;
143 
144 	/*
145 	 * Preprocess:
146 	 *	Copy the input (bytewise) array into a wordwise array.
147 	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
148 	 */
149 	memset(words, '\0', sizeof words);
150 	for (i = 0; i < IN6ADDRSZ; i++)
151 		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
152 	best.base = -1;
153 	cur.base = -1;
154 	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
155 		if (words[i] == 0) {
156 			if (cur.base == -1)
157 				cur.base = i, cur.len = 1;
158 			else
159 				cur.len++;
160 		} else {
161 			if (cur.base != -1) {
162 				if (best.base == -1 || cur.len > best.len)
163 					best = cur;
164 				cur.base = -1;
165 			}
166 		}
167 	}
168 	if (cur.base != -1) {
169 		if (best.base == -1 || cur.len > best.len)
170 			best = cur;
171 	}
172 	if (best.base != -1 && best.len < 2)
173 		best.base = -1;
174 
175 	/*
176 	 * Format the result.
177 	 */
178 	tp = tmp;
179 	ep = tmp + sizeof(tmp);
180 	for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
181 		/* Are we inside the best run of 0x00's? */
182 		if (best.base != -1 && i >= best.base &&
183 		    i < (best.base + best.len)) {
184 			if (i == best.base) {
185 				if (tp + 1 >= ep)
186 					return (NULL);
187 				*tp++ = ':';
188 			}
189 			continue;
190 		}
191 		/* Are we following an initial run of 0x00s or any real hex? */
192 		if (i != 0) {
193 			if (tp + 1 >= ep)
194 				return (NULL);
195 			*tp++ = ':';
196 		}
197 		/* Is this address an encapsulated IPv4? */
198 		if (i == 6 && best.base == 0 &&
199 		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
200 			if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
201 				return (NULL);
202 			tp += strlen(tp);
203 			break;
204 		}
205 		advance = snprintf(tp, ep - tp, "%x", words[i]);
206 		if (advance <= 0 || advance >= ep - tp)
207 			return (NULL);
208 		tp += advance;
209 	}
210 	/* Was it a trailing run of 0x00's? */
211 	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
212 		if (tp + 1 >= ep)
213 			return (NULL);
214 		*tp++ = ':';
215 	}
216 	if (tp + 1 >= ep)
217 		return (NULL);
218 	*tp++ = '\0';
219 
220 	/*
221 	 * Check for overflow, copy, and we're done.
222 	 */
223 	if ((size_t)(tp - tmp) > size) {
224 		errno = ENOSPC;
225 		return (NULL);
226 	}
227 	strlcpy(dst, tmp, size);
228 	return (dst);
229 }
230 
231 #endif /* !HAVE_INET_NTOP */
232