inet_cidr_ntop.c revision 270838 
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 1.7 2006/10/11 02:18:18 marka Exp $";
20#endif
21#include <sys/cdefs.h>
22__FBSDID("$FreeBSD: stable/10/lib/libc/inet/inet_cidr_ntop.c 270838 2014-08-30 10:16:25Z ume $");
23
24#include "port_before.h"
25
26#include <sys/types.h>
27#include <sys/socket.h>
28#include <netinet/in.h>
29#include <arpa/nameser.h>
30#include <arpa/inet.h>
31
32#include <errno.h>
33#include <stdio.h>
34#include <string.h>
35#include <stdlib.h>
36
37#include "port_after.h"
38
39#ifdef SPRINTF_CHAR
40# define SPRINTF(x) strlen(sprintf/**/x)
41#else
42# define SPRINTF(x) ((size_t)sprintf x)
43#endif
44
45static char *
46inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size);
47static char *
48inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size);
49
50/*%
51 * char *
52 * inet_cidr_ntop(af, src, bits, dst, size)
53 *	convert network address from network to presentation format.
54 *	"src"'s size is determined from its "af".
55 * return:
56 *	pointer to dst, or NULL if an error occurred (check errno).
57 * note:
58 *	192.5.5.1/28 has a nonzero host part, which means it isn't a network
59 *	as called for by inet_net_ntop() but it can be a host address with
60 *	an included netmask.
61 * author:
62 *	Paul Vixie (ISC), October 1998
63 */
64char *
65inet_cidr_ntop(int af, const void *src, int bits, char *dst, size_t size) {
66	switch (af) {
67	case AF_INET:
68		return (inet_cidr_ntop_ipv4(src, bits, dst, size));
69	case AF_INET6:
70		return (inet_cidr_ntop_ipv6(src, bits, dst, size));
71	default:
72		errno = EAFNOSUPPORT;
73		return (NULL);
74	}
75}
76
77static int
78decoct(const u_char *src, int bytes, char *dst, size_t size) {
79	char *odst = dst;
80	char *t;
81	int b;
82
83	for (b = 1; b <= bytes; b++) {
84		if (size < sizeof "255.")
85			return (0);
86		t = dst;
87		dst += SPRINTF((dst, "%u", *src++));
88		if (b != bytes) {
89			*dst++ = '.';
90			*dst = '\0';
91		}
92		size -= (size_t)(dst - t);
93	}
94	return (dst - odst);
95}
96
97/*%
98 * static char *
99 * inet_cidr_ntop_ipv4(src, bits, dst, size)
100 *	convert IPv4 network address from network to presentation format.
101 *	"src"'s size is determined from its "af".
102 * return:
103 *	pointer to dst, or NULL if an error occurred (check errno).
104 * note:
105 *	network byte order assumed.  this means 192.5.5.240/28 has
106 *	0b11110000 in its fourth octet.
107 * author:
108 *	Paul Vixie (ISC), October 1998
109 */
110static char *
111inet_cidr_ntop_ipv4(const u_char *src, int bits, char *dst, size_t size) {
112	char *odst = dst;
113	size_t len = 4;
114	size_t b;
115	size_t bytes;
116
117	if ((bits < -1) || (bits > 32)) {
118		errno = EINVAL;
119		return (NULL);
120	}
121
122	/* Find number of significant bytes in address. */
123	if (bits == -1)
124		len = 4;
125	else
126		for (len = 1, b = 1 ; b < 4U; b++)
127			if (*(src + b))
128				len = b + 1;
129
130	/* Format whole octets plus nonzero trailing octets. */
131	bytes = (((bits <= 0) ? 1 : bits) + 7) / 8;
132	if (len > bytes)
133		bytes = len;
134	b = decoct(src, bytes, dst, size);
135	if (b == 0U)
136		goto emsgsize;
137	dst += b;
138	size -= b;
139
140	if (bits != -1) {
141		/* Format CIDR /width. */
142		if (size < sizeof "/32")
143			goto emsgsize;
144		dst += SPRINTF((dst, "/%u", bits));
145	}
146
147	return (odst);
148
149 emsgsize:
150	errno = EMSGSIZE;
151	return (NULL);
152}
153
154static char *
155inet_cidr_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
156	/*
157	 * Note that int32_t and int16_t need only be "at least" large enough
158	 * to contain a value of the specified size.  On some systems, like
159	 * Crays, there is no such thing as an integer variable with 16 bits.
160	 * Keep this in mind if you think this function should have been coded
161	 * to use pointer overlays.  All the world's not a VAX.
162	 */
163	char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255/128"];
164	char *tp;
165	struct { int base, len; } best, cur;
166	u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
167	int i;
168
169	if ((bits < -1) || (bits > 128)) {
170		errno = EINVAL;
171		return (NULL);
172	}
173
174	/*
175	 * Preprocess:
176	 *	Copy the input (bytewise) array into a wordwise array.
177	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
178	 */
179	memset(words, '\0', sizeof words);
180	for (i = 0; i < NS_IN6ADDRSZ; i++)
181		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
182	best.base = -1;
183	best.len = 0;
184	cur.base = -1;
185	cur.len = 0;
186	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
187		if (words[i] == 0) {
188			if (cur.base == -1)
189				cur.base = i, cur.len = 1;
190			else
191				cur.len++;
192		} else {
193			if (cur.base != -1) {
194				if (best.base == -1 || cur.len > best.len)
195					best = cur;
196				cur.base = -1;
197			}
198		}
199	}
200	if (cur.base != -1) {
201		if (best.base == -1 || cur.len > best.len)
202			best = cur;
203	}
204	if (best.base != -1 && best.len < 2)
205		best.base = -1;
206
207	/*
208	 * Format the result.
209	 */
210	tp = tmp;
211	for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
212		/* Are we inside the best run of 0x00's? */
213		if (best.base != -1 && i >= best.base &&
214		    i < (best.base + best.len)) {
215			if (i == best.base)
216				*tp++ = ':';
217			continue;
218		}
219		/* Are we following an initial run of 0x00s or any real hex? */
220		if (i != 0)
221			*tp++ = ':';
222		/* Is this address an encapsulated IPv4? */
223		if (i == 6 && best.base == 0 && (best.len == 6 ||
224		    (best.len == 7 && words[7] != 0x0001) ||
225		    (best.len == 5 && words[5] == 0xffff))) {
226			int n;
227
228			if (src[15] || bits == -1 || bits > 120)
229				n = 4;
230			else if (src[14] || bits > 112)
231				n = 3;
232			else
233				n = 2;
234			n = decoct(src+12, n, tp, sizeof tmp - (tp - tmp));
235			if (n == 0) {
236				errno = EMSGSIZE;
237				return (NULL);
238			}
239			tp += strlen(tp);
240			break;
241		}
242		tp += SPRINTF((tp, "%x", words[i]));
243	}
244
245	/* Was it a trailing run of 0x00's? */
246	if (best.base != -1 && (best.base + best.len) ==
247	    (NS_IN6ADDRSZ / NS_INT16SZ))
248		*tp++ = ':';
249	*tp = '\0';
250
251	if (bits != -1)
252		tp += SPRINTF((tp, "/%u", bits));
253
254	/*
255	 * Check for overflow, copy, and we're done.
256	 */
257	if ((size_t)(tp - tmp) > size) {
258		errno = EMSGSIZE;
259		return (NULL);
260	}
261	strcpy(dst, tmp);
262	return (dst);
263}
264
265/*! \file */
266