1/*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1998,1999 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)
19static const char rcsid[] = "$Id: inet_cidr_ntop.c,v 1.4.18.3 2006/10/11 02:32:47 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/nameser.h>
28#include <arpa/inet.h>
29
30#include <errno.h>
31#include <stdio.h>
32#include <string.h>
33#include <stdlib.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
43static char *
44inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size);
45static char *
46inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size);
47
48/*%
49 * char *
50 * inet_cidr_ntop(af, src, bits, dst, size)
51 *	convert network address from network to presentation format.
52 *	"src"'s size is determined from its "af".
53 * return:
54 *	pointer to dst, or NULL if an error occurred (check errno).
55 * note:
56 *	192.5.5.1/28 has a nonzero host part, which means it isn't a network
57 *	as called for by inet_net_ntop() but it can be a host address with
58 *	an included netmask.
59 * author:
60 *	Paul Vixie (ISC), October 1998
61 */
62char *
63inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) {
64	switch (af) {
65	case AF_INET:
66		return (inet_cidr_ntop_ipv4(src, bits, dst, size));
67	case AF_INET6:
68		return (inet_cidr_ntop_ipv6(src, bits, dst, size));
69	default:
70		errno = EAFNOSUPPORT;
71		return (NULL);
72	}
73}
74
75static int
76decoct(const u_char *src, int bytes, char *dst, size_t size) {
77	char *odst = dst;
78	char *t;
79	int b;
80
81	for (b = 1; b <= bytes; b++) {
82		if (size < sizeof "255.")
83			return (0);
84		t = dst;
85		dst += SPRINTF((dst, "%u", *src++));
86		if (b != bytes) {
87			*dst++ = '.';
88			*dst = '\0';
89		}
90		size -= (size_t)(dst - t);
91	}
92	return (dst - odst);
93}
94
95/*%
96 * static char *
97 * inet_cidr_ntop_ipv4(src, bits, dst, size)
98 *	convert IPv4 network address from network to presentation format.
99 *	"src"'s size is determined from its "af".
100 * return:
101 *	pointer to dst, or NULL if an error occurred (check errno).
102 * note:
103 *	network byte order assumed.  this means 192.5.5.240/28 has
104 *	0b11110000 in its fourth octet.
105 * author:
106 *	Paul Vixie (ISC), October 1998
107 */
108static char *
109inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) {
110	char *odst = dst;
111	size_t len = 4;
112	size_t b;
113	size_t bytes;
114
115	if ((bits < -1) || (bits > 32)) {
116		errno = EINVAL;
117		return (NULL);
118	}
119
120	/* Find number of significant bytes in address. */
121	if (bits == -1)
122		len = 4;
123	else
124		for (len = 1, b = 1 ; b < 4U; b++)
125			if (*(src + b))
126				len = b + 1;
127
128	/* Format whole octets plus nonzero trailing octets. */
129	bytes = (((bits <= 0) ? 1 : bits) + 7) / 8;
130	if (len > bytes)
131		bytes = len;
132	b = decoct(src, bytes, dst, size);
133	if (b == 0U)
134		goto emsgsize;
135	dst += b;
136	size -= b;
137
138	if (bits != -1) {
139		/* Format CIDR /width. */
140		if (size < sizeof "/32")
141			goto emsgsize;
142		dst += SPRINTF((dst, "/%u", bits));
143	}
144
145	return (odst);
146
147 emsgsize:
148	errno = EMSGSIZE;
149	return (NULL);
150}
151
152static char *
153inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
154	/*
155	 * Note that int32_t and int16_t need only be "at least" large enough
156	 * to contain a value of the specified size.  On some systems, like
157	 * Crays, there is no such thing as an integer variable with 16 bits.
158	 * Keep this in mind if you think this function should have been coded
159	 * to use pointer overlays.  All the world's not a VAX.
160	 */
161	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"];
162	char *tp;
163	struct { int base, len; } best, cur;
164	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
165	int i;
166
167	if ((bits < -1) || (bits > 128)) {
168		errno = EINVAL;
169		return (NULL);
170	}
171
172	/*
173	 * Preprocess:
174	 *	Copy the input (bytewise) array into a wordwise array.
175	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
176	 */
177	memset(words, '\0', sizeof words);
178	for (i = 0; i < NS_IN6ADDRSZ; i++)
179		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
180	best.base = -1;
181	best.len = 0;
182	cur.base = -1;
183	cur.len = 0;
184	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
185		if (words[i] == 0) {
186			if (cur.base == -1)
187				cur.base = i, cur.len = 1;
188			else
189				cur.len++;
190		} else {
191			if (cur.base != -1) {
192				if (best.base == -1 || cur.len > best.len)
193					best = cur;
194				cur.base = -1;
195			}
196		}
197	}
198	if (cur.base != -1) {
199		if (best.base == -1 || cur.len > best.len)
200			best = cur;
201	}
202	if (best.base != -1 && best.len < 2)
203		best.base = -1;
204
205	/*
206	 * Format the result.
207	 */
208	tp = tmp;
209	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
210		/* Are we inside the best run of 0x00's? */
211		if (best.base != -1 && i >= best.base &&
212		    i < (best.base + best.len)) {
213			if (i == best.base)
214				*tp++ = ':';
215			continue;
216		}
217		/* Are we following an initial run of 0x00s or any real hex? */
218		if (i != 0)
219			*tp++ = ':';
220		/* Is this address an encapsulated IPv4? */
221		if (i == 6 && best.base == 0 && (best.len == 6 ||
222		    (best.len == 7 && words[7] != 0x0001) ||
223		    (best.len == 5 && words[5] == 0xffff))) {
224			int n;
225
226			if (src[15] || bits == -1 || bits > 120)
227				n = 4;
228			else if (src[14] || bits > 112)
229				n = 3;
230			else
231				n = 2;
232			n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp));
233			if (n == 0) {
234				errno = EMSGSIZE;
235				return (NULL);
236			}
237			tp += strlen(tp);
238			break;
239		}
240		tp += SPRINTF((tp, "%x", words[i]));
241	}
242
243	/* Was it a trailing run of 0x00's? */
244	if (best.base != -1 && (best.base + best.len) ==
245	    (NS_IN6ADDRSZ / NS_INT16SZ))
246		*tp++ = ':';
247	*tp = '\0';
248
249	if (bits != -1)
250		tp += SPRINTF((tp, "/%u", bits));
251
252	/*
253	 * Check for overflow, copy, and we're done.
254	 */
255	if ((size_t)(tp - tmp) > size) {
256		errno = EMSGSIZE;
257		return (NULL);
258	}
259	strcpy(dst, tmp);
260	return (dst);
261}
262
263/*! \file */
264