xref: /illumos-gate/usr/src/lib/libresolv2/common/inet/inet_net_ntop.c (revision aedf2b3bb56b025fcaf87b49ec6c8aeea07f16d7)
1 /*
2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3  * Copyright (c) 1996,1999 by Internet Software Consortium.
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #if defined(LIBC_SCCS) && !defined(lint)
19 static const char rcsid[] = "$Id: inet_net_ntop.c,v 1.5 2006/06/20 02:50:14 marka Exp $";
20 #endif
21 
22 #include "port_before.h"
23 
24 #include <sys/types.h>
25 #include <sys/socket.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
28 
29 #include <errno.h>
30 #include <stdio.h>
31 #include <string.h>
32 #include <stdlib.h>
33 
34 #include "port_after.h"
35 
36 #ifdef SPRINTF_CHAR
37 # define SPRINTF(x) strlen(sprintf/**/x)
38 #else
39 # define SPRINTF(x) ((size_t)sprintf x)
40 #endif
41 
42 static char *	inet_net_ntop_ipv4 __P((const u_char *src, int bits,
43 					char *dst, size_t size));
44 static char *	inet_net_ntop_ipv6 __P((const u_char *src, int bits,
45 					char *dst, size_t size));
46 
47 /*%
48  * char *
49  * inet_net_ntop(af, src, bits, dst, size)
50  *	convert network number from network to presentation format.
51  *	generates CIDR style result always.
52  * return:
53  *	pointer to dst, or NULL if an error occurred (check errno).
54  * author:
55  *	Paul Vixie (ISC), July 1996
56  */
57 char *
58 inet_net_ntop(af, src, bits, dst, size)
59 	int af;
60 	const void *src;
61 	int bits;
62 	char *dst;
63 	size_t size;
64 {
65 	switch (af) {
66 	case AF_INET:
67 		return (inet_net_ntop_ipv4(src, bits, dst, size));
68 	case AF_INET6:
69 		return (inet_net_ntop_ipv6(src, bits, dst, size));
70 	default:
71 		errno = EAFNOSUPPORT;
72 		return (NULL);
73 	}
74 }
75 
76 /*%
77  * static char *
78  * inet_net_ntop_ipv4(src, bits, dst, size)
79  *	convert IPv4 network number from network to presentation format.
80  *	generates CIDR style result always.
81  * return:
82  *	pointer to dst, or NULL if an error occurred (check errno).
83  * note:
84  *	network byte order assumed.  this means 192.5.5.240/28 has
85  *	0b11110000 in its fourth octet.
86  * author:
87  *	Paul Vixie (ISC), July 1996
88  */
89 static char *
90 inet_net_ntop_ipv4(src, bits, dst, size)
91 	const u_char *src;
92 	int bits;
93 	char *dst;
94 	size_t size;
95 {
96 	char *odst = dst;
97 	char *t;
98 	u_int m;
99 	int b;
100 
101 	if (bits < 0 || bits > 32) {
102 		errno = EINVAL;
103 		return (NULL);
104 	}
105 
106 	if (bits == 0) {
107 		if (size < sizeof "0")
108 			goto emsgsize;
109 		*dst++ = '0';
110 		size--;
111 		*dst = '\0';
112 	}
113 
114 	/* Format whole octets. */
115 	for (b = bits / 8; b > 0; b--) {
116 		if (size <= sizeof "255.")
117 			goto emsgsize;
118 		t = dst;
119 		dst += SPRINTF((dst, "%u", *src++));
120 		if (b > 1) {
121 			*dst++ = '.';
122 			*dst = '\0';
123 		}
124 		size -= (size_t)(dst - t);
125 	}
126 
127 	/* Format partial octet. */
128 	b = bits % 8;
129 	if (b > 0) {
130 		if (size <= sizeof ".255")
131 			goto emsgsize;
132 		t = dst;
133 		if (dst != odst)
134 			*dst++ = '.';
135 		m = ((1 << b) - 1) << (8 - b);
136 		dst += SPRINTF((dst, "%u", *src & m));
137 		size -= (size_t)(dst - t);
138 	}
139 
140 	/* Format CIDR /width. */
141 	if (size <= sizeof "/32")
142 		goto emsgsize;
143 	dst += SPRINTF((dst, "/%u", bits));
144 	return (odst);
145 
146  emsgsize:
147 	errno = EMSGSIZE;
148 	return (NULL);
149 }
150 
151 /*%
152  * static char *
153  * inet_net_ntop_ipv6(src, bits, fakebits, dst, size)
154  *	convert IPv6 network number from network to presentation format.
155  *	generates CIDR style result always. Picks the shortest representation
156  *	unless the IP is really IPv4.
157  *	always prints specified number of bits (bits).
158  * return:
159  *	pointer to dst, or NULL if an error occurred (check errno).
160  * note:
161  *	network byte order assumed.  this means 192.5.5.240/28 has
162  *	0x11110000 in its fourth octet.
163  * author:
164  *	Vadim Kogan (UCB), June 2001
165  *  Original version (IPv4) by Paul Vixie (ISC), July 1996
166  */
167 
168 static char *
169 inet_net_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
170 	u_int	m;
171 	int	b;
172 	int	p;
173 	int	zero_s, zero_l, tmp_zero_s, tmp_zero_l;
174 	int	i;
175 	int	is_ipv4 = 0;
176 	unsigned char inbuf[16];
177 	char outbuf[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];
178 	char	*cp;
179 	int	words;
180 	u_char	*s;
181 
182 	if (bits < 0 || bits > 128) {
183 		errno = EINVAL;
184 		return (NULL);
185 	}
186 
187 	cp = outbuf;
188 
189 	if (bits == 0) {
190 		*cp++ = ':';
191 		*cp++ = ':';
192 		*cp = '\0';
193 	} else {
194 		/* Copy src to private buffer.  Zero host part. */
195 		p = (bits + 7) / 8;
196 		memcpy(inbuf, src, p);
197 		memset(inbuf + p, 0, 16 - p);
198 		b = bits % 8;
199 		if (b != 0) {
200 			m = ~0 << (8 - b);
201 			inbuf[p-1] &= m;
202 		}
203 
204 		s = inbuf;
205 
206 		/* how many words need to be displayed in output */
207 		words = (bits + 15) / 16;
208 		if (words == 1)
209 			words = 2;
210 
211 		/* Find the longest substring of zero's */
212 		zero_s = zero_l = tmp_zero_s = tmp_zero_l = 0;
213 		for (i = 0; i < (words * 2); i += 2) {
214 			if ((s[i] | s[i+1]) == 0) {
215 				if (tmp_zero_l == 0)
216 					tmp_zero_s = i / 2;
217 				tmp_zero_l++;
218 			} else {
219 				if (tmp_zero_l && zero_l < tmp_zero_l) {
220 					zero_s = tmp_zero_s;
221 					zero_l = tmp_zero_l;
222 					tmp_zero_l = 0;
223 				}
224 			}
225 		}
226 
227 		if (tmp_zero_l && zero_l < tmp_zero_l) {
228 			zero_s = tmp_zero_s;
229 			zero_l = tmp_zero_l;
230 		}
231 
232 		if (zero_l != words && zero_s == 0 && ((zero_l == 6) ||
233 		    ((zero_l == 5 && s[10] == 0xff && s[11] == 0xff) ||
234 		    ((zero_l == 7 && s[14] != 0 && s[15] != 1)))))
235 			is_ipv4 = 1;
236 
237 		/* Format whole words. */
238 		for (p = 0; p < words; p++) {
239 			if (zero_l != 0 && p >= zero_s && p < zero_s + zero_l) {
240 				/* Time to skip some zeros */
241 				if (p == zero_s)
242 					*cp++ = ':';
243 				if (p == words - 1)
244 					*cp++ = ':';
245 				s++;
246 				s++;
247 				continue;
248 			}
249 
250 			if (is_ipv4 && p > 5 ) {
251 				*cp++ = (p == 6) ? ':' : '.';
252 				cp += SPRINTF((cp, "%u", *s++));
253 				/* we can potentially drop the last octet */
254 				if (p != 7 || bits > 120) {
255 					*cp++ = '.';
256 					cp += SPRINTF((cp, "%u", *s++));
257 				}
258 			} else {
259 				if (cp != outbuf)
260 					*cp++ = ':';
261 				cp += SPRINTF((cp, "%x", *s * 256 + s[1]));
262 				s += 2;
263 			}
264 		}
265 	}
266 	/* Format CIDR /width. */
267 	sprintf(cp, "/%u", bits);
268 	if (strlen(outbuf) + 1 > size)
269 		goto emsgsize;
270 	strcpy(dst, outbuf);
271 
272 	return (dst);
273 
274 emsgsize:
275 	errno = EMSGSIZE;
276 	return (NULL);
277 }
278 
279 /*! \file */
280