xref: /titanic_41/usr/src/lib/libnsl/nss/inet_ntop.c (revision 15d9d0b528387242011cdcc6190c9e598cfe3a07)
1 /*
2  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
3  * Use is subject to license terms.
4  */
5 
6 /*
7  * Copyright (c) 1996 by Internet Software Consortium.
8  *
9  * Permission to use, copy, modify, and distribute this software for any
10  * purpose with or without fee is hereby granted, provided that the above
11  * copyright notice and this permission notice appear in all copies.
12  *
13  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
14  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
15  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
16  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
17  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
18  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
19  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
20  * SOFTWARE.
21  */
22 
23 #pragma ident	"%Z%%M%	%I%	%E% SMI"
24 
25 #include "mt.h"
26 #include <stdlib.h>
27 #include <ctype.h>
28 #include <string.h>
29 #include <strings.h>
30 #include <netdb.h>
31 #include <stdio.h>
32 #include <arpa/inet.h>
33 #include <netinet/in.h>
34 #include <sys/socket.h>
35 #include <errno.h>
36 
37 static const char *inet_ntop4(const uchar_t *, char *, socklen_t);
38 static const char *inet_ntop6(const uchar_t *, char *, socklen_t);
39 
40 /*
41  * char *
42  * inet_ntop(af, src, dst, size)
43  *	convert a network format address to presentation format.
44  * return:
45  *	pointer to presentation format address (`dst'), or NULL (see errno).
46  */
47 const char *
48 inet_ntop(int af, const void *src, char *dst, socklen_t size)
49 {
50 	switch (af) {
51 	case AF_INET:
52 		return (inet_ntop4(src, dst, size));
53 	case AF_INET6:
54 		return (inet_ntop6(src, dst, size));
55 	default:
56 		errno = EAFNOSUPPORT;
57 		return (NULL);
58 	}
59 	/* NOTREACHED */
60 }
61 
62 /*
63  * const char *
64  * inet_ntop4(src, dst, size)
65  *	format an IPv4 address, more or less like inet_ntoa()
66  * return:
67  *	`dst' (as a const)
68  * notes:
69  *	(1) uses no statics
70  *	(2) takes a uchar_t* not an in_addr as input
71  */
72 
73 #ifdef SPRINTF_CHAR
74 /* CSTYLED */
75 #define	SPRINTF(x) strlen(sprintf/**/x)
76 #else
77 #define	SPRINTF(x) ((size_t)sprintf x)
78 #endif
79 
80 static const char *
81 inet_ntop4(const uchar_t *src, char *dst, socklen_t size)
82 {
83 	static const char fmt[] = "%u.%u.%u.%u";
84 	char tmp[sizeof ("255.255.255.255")];
85 
86 	if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) {
87 		errno = ENOSPC;
88 		return (NULL);
89 	}
90 	(void) strcpy(dst, tmp);
91 	return (dst);
92 }
93 
94 /*
95  * const char *
96  * inet_ntop6(src, dst, size)
97  *	convert IPv6 binary address into presentation (printable) format
98  */
99 #define	INADDRSZ	4
100 #define	IN6ADDRSZ	16
101 #define	INT16SZ		2
102 static const char *
103 inet_ntop6(const uchar_t *src, char *dst, socklen_t size)
104 {
105 	/*
106 	 * Note that int32_t and int16_t need only be "at least" large enough
107 	 * to contain a value of the specified size.  On some systems, like
108 	 * Crays, there is no such thing as an integer variable with 16 bits.
109 	 * Keep this in mind if you think this function should have been coded
110 	 * to use pointer overlays.  All the world's not a VAX.
111 	 */
112 	char tmp[sizeof ("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")], *tp;
113 	struct { int base, len; } best, cur;
114 	uint_t words[IN6ADDRSZ / INT16SZ];
115 	int i;
116 
117 	/*
118 	 * Preprocess:
119 	 *	Copy the input (bytewise) array into a wordwise array.
120 	 *	Find the longest run of 0x00's in src[] for :: shorthanding.
121 	 */
122 	(void) memset(words, '\0', sizeof (words));
123 	for (i = 0; i < IN6ADDRSZ; i++)
124 		words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
125 	best.base = -1;
126 	cur.base = -1;
127 	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
128 		if (words[i] == 0) {
129 			if (cur.base == -1)
130 				cur.base = i, cur.len = 1;
131 			else
132 				cur.len++;
133 		} else {
134 			if (cur.base != -1) {
135 				if (best.base == -1 || cur.len > best.len)
136 					best = cur;
137 				cur.base = -1;
138 			}
139 		}
140 	}
141 	if (cur.base != -1) {
142 		if (best.base == -1 || cur.len > best.len)
143 			best = cur;
144 	}
145 	if (best.base != -1 && best.len < 2)
146 		best.base = -1;
147 
148 	/*
149 	 * Format the result.
150 	 */
151 	tp = tmp;
152 	for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
153 		/* Are we inside the best run of 0x00's? */
154 		if (best.base != -1 && i >= best.base &&
155 		    i < (best.base + best.len)) {
156 			if (i == best.base)
157 				*tp++ = ':';
158 			continue;
159 		}
160 		/* Are we following an initial run of 0x00s or any real hex? */
161 		if (i != 0)
162 			*tp++ = ':';
163 		/* Is this address an encapsulated IPv4? */
164 		if (i == 6 && best.base == 0 &&
165 		    (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
166 			if (!inet_ntop4(src+12, tp, sizeof (tmp) - (tp - tmp)))
167 				return (NULL);
168 			tp += strlen(tp);
169 			break;
170 		}
171 		tp += SPRINTF((tp, "%x", words[i]));
172 	}
173 	/* Was it a trailing run of 0x00's? */
174 	if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
175 		*tp++ = ':';
176 	*tp++ = '\0';
177 
178 	/*
179 	 * Check for overflow, copy, and we're done.
180 	 */
181 	if ((int)(tp - tmp) > size) {
182 		errno = ENOSPC;
183 		return (NULL);
184 	}
185 	(void) strcpy(dst, tmp);
186 	return (dst);
187 }
188