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 #include <limits.h>
34 
35 #include "port_after.h"
36 
37 #ifdef SPRINTF_CHAR
38 # define SPRINTF(x) strlen(sprintf/**/x)
39 #else
40 # define SPRINTF(x) ((size_t)sprintf x)
41 #endif
42 
43 static char *	inet_net_ntop_ipv4 __P((const u_char *src, int bits,
44 					char *dst, size_t size));
45 static char *	inet_net_ntop_ipv6 __P((const u_char *src, int bits,
46 					char *dst, size_t size));
47 
48 /*%
49  * char *
50  * inet_net_ntop(af, src, bits, dst, size)
51  *	convert network number from network to presentation format.
52  *	generates CIDR style result always.
53  * return:
54  *	pointer to dst, or NULL if an error occurred (check errno).
55  * author:
56  *	Paul Vixie (ISC), July 1996
57  */
58 char *
inet_net_ntop(af,src,bits,dst,size)59 inet_net_ntop(af, src, bits, dst, size)
60 	int af;
61 	const void *src;
62 	int bits;
63 	char *dst;
64 	size_t size;
65 {
66 	switch (af) {
67 	case AF_INET:
68 		return (inet_net_ntop_ipv4(src, bits, dst, size));
69 	case AF_INET6:
70 		return (inet_net_ntop_ipv6(src, bits, dst, size));
71 	default:
72 		errno = EAFNOSUPPORT;
73 		return (NULL);
74 	}
75 }
76 
77 /*%
78  * static char *
79  * inet_net_ntop_ipv4(src, bits, dst, size)
80  *	convert IPv4 network number from network to presentation format.
81  *	generates CIDR style result always.
82  * return:
83  *	pointer to dst, or NULL if an error occurred (check errno).
84  * note:
85  *	network byte order assumed.  this means 192.5.5.240/28 has
86  *	0b11110000 in its fourth octet.
87  * author:
88  *	Paul Vixie (ISC), July 1996
89  */
90 static char *
inet_net_ntop_ipv4(src,bits,dst,size)91 inet_net_ntop_ipv4(src, bits, dst, size)
92 	const u_char *src;
93 	int bits;
94 	char *dst;
95 	size_t size;
96 {
97 	char *odst = dst;
98 	char *t;
99 	u_int m;
100 	int b;
101 
102 	if (bits < 0 || bits > 32) {
103 		errno = EINVAL;
104 		return (NULL);
105 	}
106 
107 	if (bits == 0) {
108 		if (size < sizeof "0")
109 			goto emsgsize;
110 		*dst++ = '0';
111 		size--;
112 		*dst = '\0';
113 	}
114 
115 	/* Format whole octets. */
116 	for (b = bits / 8; b > 0; b--) {
117 		if (size <= sizeof "255.")
118 			goto emsgsize;
119 		t = dst;
120 		dst += SPRINTF((dst, "%u", *src++));
121 		if (b > 1) {
122 			*dst++ = '.';
123 			*dst = '\0';
124 		}
125 		size -= (size_t)(dst - t);
126 	}
127 
128 	/* Format partial octet. */
129 	b = bits % 8;
130 	if (b > 0) {
131 		if (size <= sizeof ".255")
132 			goto emsgsize;
133 		t = dst;
134 		if (dst != odst)
135 			*dst++ = '.';
136 		m = ((1 << b) - 1) << (8 - b);
137 		dst += SPRINTF((dst, "%u", *src & m));
138 		size -= (size_t)(dst - t);
139 	}
140 
141 	/* Format CIDR /width. */
142 	if (size <= sizeof "/32")
143 		goto emsgsize;
144 	dst += SPRINTF((dst, "/%u", bits));
145 	return (odst);
146 
147  emsgsize:
148 	errno = EMSGSIZE;
149 	return (NULL);
150 }
151 
152 /*%
153  * static char *
154  * inet_net_ntop_ipv6(src, bits, fakebits, dst, size)
155  *	convert IPv6 network number from network to presentation format.
156  *	generates CIDR style result always. Picks the shortest representation
157  *	unless the IP is really IPv4.
158  *	always prints specified number of bits (bits).
159  * return:
160  *	pointer to dst, or NULL if an error occurred (check errno).
161  * note:
162  *	network byte order assumed.  this means 192.5.5.240/28 has
163  *	0x11110000 in its fourth octet.
164  * author:
165  *	Vadim Kogan (UCB), June 2001
166  *  Original version (IPv4) by Paul Vixie (ISC), July 1996
167  */
168 
169 static char *
inet_net_ntop_ipv6(const u_char * src,int bits,char * dst,size_t size)170 inet_net_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
171 	u_int	m;
172 	int	b;
173 	int	p;
174 	int	zero_s, zero_l, tmp_zero_s, tmp_zero_l;
175 	int	i;
176 	int	is_ipv4 = 0;
177 	unsigned char inbuf[16];
178 	char outbuf[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];
179 	char	*cp;
180 	int	words;
181 	u_char	*s;
182 
183 	if (bits < 0 || bits > 128) {
184 		errno = EINVAL;
185 		return (NULL);
186 	}
187 
188 	cp = outbuf;
189 
190 	if (bits == 0) {
191 		*cp++ = ':';
192 		*cp++ = ':';
193 		*cp = '\0';
194 	} else {
195 		/* Copy src to private buffer.  Zero host part. */
196 		p = (bits + 7) / 8;
197 		memcpy(inbuf, src, p);
198 		memset(inbuf + p, 0, 16 - p);
199 		b = bits % 8;
200 		if (b != 0) {
201 			m = UINT_MAX << (8 - b);
202 			inbuf[p-1] &= m;
203 		}
204 
205 		s = inbuf;
206 
207 		/* how many words need to be displayed in output */
208 		words = (bits + 15) / 16;
209 		if (words == 1)
210 			words = 2;
211 
212 		/* Find the longest substring of zero's */
213 		zero_s = zero_l = tmp_zero_s = tmp_zero_l = 0;
214 		for (i = 0; i < (words * 2); i += 2) {
215 			if ((s[i] | s[i+1]) == 0) {
216 				if (tmp_zero_l == 0)
217 					tmp_zero_s = i / 2;
218 				tmp_zero_l++;
219 			} else {
220 				if (tmp_zero_l && zero_l < tmp_zero_l) {
221 					zero_s = tmp_zero_s;
222 					zero_l = tmp_zero_l;
223 					tmp_zero_l = 0;
224 				}
225 			}
226 		}
227 
228 		if (tmp_zero_l && zero_l < tmp_zero_l) {
229 			zero_s = tmp_zero_s;
230 			zero_l = tmp_zero_l;
231 		}
232 
233 		if (zero_l != words && zero_s == 0 && ((zero_l == 6) ||
234 		    ((zero_l == 5 && s[10] == 0xff && s[11] == 0xff) ||
235 		    ((zero_l == 7 && s[14] != 0 && s[15] != 1)))))
236 			is_ipv4 = 1;
237 
238 		/* Format whole words. */
239 		for (p = 0; p < words; p++) {
240 			if (zero_l != 0 && p >= zero_s && p < zero_s + zero_l) {
241 				/* Time to skip some zeros */
242 				if (p == zero_s)
243 					*cp++ = ':';
244 				if (p == words - 1)
245 					*cp++ = ':';
246 				s++;
247 				s++;
248 				continue;
249 			}
250 
251 			if (is_ipv4 && p > 5 ) {
252 				*cp++ = (p == 6) ? ':' : '.';
253 				cp += SPRINTF((cp, "%u", *s++));
254 				/* we can potentially drop the last octet */
255 				if (p != 7 || bits > 120) {
256 					*cp++ = '.';
257 					cp += SPRINTF((cp, "%u", *s++));
258 				}
259 			} else {
260 				if (cp != outbuf)
261 					*cp++ = ':';
262 				cp += SPRINTF((cp, "%x", *s * 256 + s[1]));
263 				s += 2;
264 			}
265 		}
266 	}
267 	/* Format CIDR /width. */
268 	sprintf(cp, "/%u", bits);
269 	if (strlen(outbuf) + 1 > size)
270 		goto emsgsize;
271 	strcpy(dst, outbuf);
272 
273 	return (dst);
274 
275 emsgsize:
276 	errno = EMSGSIZE;
277 	return (NULL);
278 }
279 
280 /*! \file */
281