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 #include <arpa/nameser.h>
39 #include <string.h>
40 #include <errno.h>
41 #include <stdio.h>
42 
43 #ifndef IN6ADDRSZ
44 #define IN6ADDRSZ   16   /* IPv6 T_AAAA */
45 #endif
46 
47 #ifndef INT16SZ
48 #define INT16SZ     2    /* for systems without 16-bit ints */
49 #endif
50 
51 /*
52  * WARNING: Don't even consider trying to compile this on a system where
53  * sizeof(int) < 4.  sizeof(int) > 4 is fine; all the world's not a VAX.
54  */
55 
56 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
57 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
58 
59 /* char *
60  * inet_ntop(af, src, dst, size)
61  *	convert a network format address to presentation format.
62  * return:
63  *	pointer to presentation format address (`dst'), or NULL (see errno).
64  * author:
65  *	Paul Vixie, 1996.
66  */
67 const char *
68 inet_ntop(af, src, dst, size)
69 	int af;
70 	const void *src;
71 	char *dst;
72 	size_t size;
73 {
74 	switch (af) {
75 	case AF_INET:
76 		return (inet_ntop4(src, dst, size));
77 	case AF_INET6:
78 		return (inet_ntop6(src, dst, size));
79 	default:
80 		errno = EAFNOSUPPORT;
81 		return (NULL);
82 	}
83 	/* NOTREACHED */
84 }
85 
86 /* const char *
87  * inet_ntop4(src, dst, size)
88  *	format an IPv4 address, more or less like inet_ntoa()
89  * return:
90  *	`dst' (as a const)
91  * notes:
92  *	(1) uses no statics
93  *	(2) takes a u_char* not an in_addr as input
94  * author:
95  *	Paul Vixie, 1996.
96  */
97 static const char *
98 inet_ntop4(src, dst, size)
99 	const u_char *src;
100 	char *dst;
101 	size_t size;
102 {
103 	static const char fmt[] = "%u.%u.%u.%u";
104 	char tmp[sizeof "255.255.255.255"];
105 	int l;
106 
107 	l = snprintf(tmp, size, fmt, src[0], src[1], src[2], src[3]);
108 	if (l <= 0 || l >= size) {
109 		errno = ENOSPC;
110 		return (NULL);
111 	}
112 	strlcpy(dst, tmp, size);
113 	return (dst);
114 }
115 
116 /* const char *
117  * inet_ntop6(src, dst, size)
118  *	convert IPv6 binary address into presentation (printable) format
119  * author:
120  *	Paul Vixie, 1996.
121  */
122 static const char *
123 inet_ntop6(src, dst, size)
124 	const u_char *src;
125 	char *dst;
126 	size_t size;
127 {
128 	/*
129 	 * Note that int32_t and int16_t need only be "at least" large enough
130 	 * to contain a value of the specified size.  On some systems, like
131 	 * Crays, there is no such thing as an integer variable with 16 bits.
132 	 * Keep this in mind if you think this function should have been coded
133 	 * to use pointer overlays.  All the world's not a VAX.
134 	 */
135 	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
136 	char *tp, *ep;
137 	struct { int base, len; } best, cur;
138 	u_int words[IN6ADDRSZ / INT16SZ];
139 	int i;
140 	int advance;
141 
142 	/*
143 	 * Preprocess:
144 	 *	Copy the input (bytewise) array into a wordwise array.
145 	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
146 	 */
147 	memset(words, '\0', sizeof words);
148 	for (i = 0; i < IN6ADDRSZ; i++)
149 		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
150 	best.base = -1;
151 	cur.base = -1;
152 	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
153 		if (words[i] == 0) {
154 			if (cur.base == -1)
155 				cur.base = i, cur.len = 1;
156 			else
157 				cur.len++;
158 		} else {
159 			if (cur.base != -1) {
160 				if (best.base == -1 || cur.len > best.len)
161 					best = cur;
162 				cur.base = -1;
163 			}
164 		}
165 	}
166 	if (cur.base != -1) {
167 		if (best.base == -1 || cur.len > best.len)
168 			best = cur;
169 	}
170 	if (best.base != -1 && best.len < 2)
171 		best.base = -1;
172 
173 	/*
174 	 * Format the result.
175 	 */
176 	tp = tmp;
177 	ep = tmp + sizeof(tmp);
178 	for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
179 		/* Are we inside the best run of 0x00's? */
180 		if (best.base != -1 && i >= best.base &&
181 		    i < (best.base + best.len)) {
182 			if (i == best.base) {
183 				if (tp + 1 >= ep)
184 					return (NULL);
185 				*tp++ = ':';
186 			}
187 			continue;
188 		}
189 		/* Are we following an initial run of 0x00s or any real hex? */
190 		if (i != 0) {
191 			if (tp + 1 >= ep)
192 				return (NULL);
193 			*tp++ = ':';
194 		}
195 		/* Is this address an encapsulated IPv4? */
196 		if (i == 6 && best.base == 0 &&
197 		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
198 			if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
199 				return (NULL);
200 			tp += strlen(tp);
201 			break;
202 		}
203 		advance = snprintf(tp, ep - tp, "%x", words[i]);
204 		if (advance <= 0 || advance >= ep - tp)
205 			return (NULL);
206 		tp += advance;
207 	}
208 	/* Was it a trailing run of 0x00's? */
209 	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
210 		if (tp + 1 >= ep)
211 			return (NULL);
212 		*tp++ = ':';
213 	}
214 	if (tp + 1 >= ep)
215 		return (NULL);
216 	*tp++ = '\0';
217 
218 	/*
219 	 * Check for overflow, copy, and we're done.
220 	 */
221 	if ((size_t)(tp - tmp) > size) {
222 		errno = ENOSPC;
223 		return (NULL);
224 	}
225 	strlcpy(dst, tmp, size);
226 	return (dst);
227 }
228 
229 #endif /* !HAVE_INET_NTOP */
230