xref: /freebsd/contrib/ldns/compat/inet_ntop.c (revision f39bffc62c1395bde25d152c7f68fdf7cbaab414)
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 <ldns/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 
49 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
50 static 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  */
60 const char *
61 inet_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  */
90 static const char *
91 inet_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  */
112 static const char *
113 inet_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