modules/ip/inet_ntop.c
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FUNCTIONS
This source file includes following functions.
- inet_ntop
- inet_ntop4
- inet_ntop6
1 /* $OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj Exp $ */
2
3 /* Copyright (c) 1996 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
10 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
11 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
12 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
13 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
14 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
15 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
16 * SOFTWARE.
17 */
18 #define __P(a) a
19
20 #if defined(LIBC_SCCS) && !defined(lint)
21 #if 0
22 static char rcsid[] = "$From: inet_ntop.c,v 8.7 1996/08/05 08:41:18 vixie Exp $";
23 #else
24 static char rcsid[] = "$OpenBSD: inet_ntop.c,v 1.1 1997/03/13 19:07:32 downsj Exp $";
25 #endif
26 #endif /* LIBC_SCCS and not lint */
27
28 #include <sys/param.h>
29 #include <sys/types.h>
30 #include <sys/socket.h>
31 #include <netinet/in.h>
32 #include <arpa/inet.h>
33 #include <arpa/nameser.h>
34
35 #include <string.h>
36 #include <errno.h>
37 #include <stdio.h>
38
39 #include "inet6def.h"
40
41 /*
42 * WARNING: Don't even consider trying to compile this on a system where
43 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
44 */
45
46 static const char *inet_ntop4 __P((const u_char *src, char *dst, size_t size));
47 static const char *inet_ntop6 __P((const u_char *src, char *dst, size_t size));
48
49 /* char *
50 * inet_ntop(af, src, dst, size)
51 * convert a network format address to presentation format.
52 * return:
53 * pointer to presentation format address (`dst'), or NULL (see errno).
54 * author:
55 * Paul Vixie, 1996.
56 */
57 const char *
58 inet_ntop(af, src, dst, size)
/* [<][>][^][v][top][bottom][index][help] */
59 int af;
60 const void *src;
61 char *dst;
62 size_t size;
63 {
64 switch (af) {
65 case AF_INET:
66 return (inet_ntop4(src, dst, size));
67 case AF_INET6:
68 return (inet_ntop6(src, dst, size));
69 default:
70 errno = EAFNOSUPPORT;
71 return (NULL);
72 }
73 /* NOTREACHED */
74 }
75
76 /* const char *
77 * inet_ntop4(src, dst, size)
78 * format an IPv4 address, more or less like inet_ntoa()
79 * return:
80 * `dst' (as a const)
81 * notes:
82 * (1) uses no statics
83 * (2) takes a u_char* not an in_addr as input
84 * author:
85 * Paul Vixie, 1996.
86 */
87 static const char *
88 inet_ntop4(src, dst, size)
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89 const u_char *src;
90 char *dst;
91 size_t size;
92 {
93 static const char fmt[] = "%u.%u.%u.%u";
94 char tmp[sizeof "255.255.255.255"];
95
96 if (sprintf(tmp, fmt, src[0], src[1], src[2], src[3]) > size) {
97 errno = ENOSPC;
98 return (NULL);
99 }
100 strcpy(dst, tmp);
101 return (dst);
102 }
103
104 /* const char *
105 * inet_ntop6(src, dst, size)
106 * convert IPv6 binary address into presentation (printable) format
107 * author:
108 * Paul Vixie, 1996.
109 */
110 static const char *
111 inet_ntop6(src, dst, size)
/* [<][>][^][v][top][bottom][index][help] */
112 const u_char *src;
113 char *dst;
114 size_t size;
115 {
116 /*
117 * Note that int32_t and int16_t need only be "at least" large enough
118 * to contain a value of the specified size. On some systems, like
119 * Crays, there is no such thing as an integer variable with 16 bits.
120 * Keep this in mind if you think this function should have been coded
121 * to use pointer overlays. All the world's not a VAX.
122 */
123 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
124 struct { int base, len; } best, cur;
125 u_int words[IN6ADDRSZ / INT16SZ];
126 int i;
127
128 /*
129 * Preprocess:
130 * Copy the input (bytewise) array into a wordwise array.
131 * Find the longest run of 0x00's in src[] for :: shorthanding.
132 */
133 memset(words, '\0', sizeof words);
134 for (i = 0; i < IN6ADDRSZ; i++)
135 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
136 best.base = -1;
137 cur.base = -1;
138 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
139 if (words[i] == 0) {
140 if (cur.base == -1)
141 cur.base = i, cur.len = 1;
142 else
143 cur.len++;
144 } else {
145 if (cur.base != -1) {
146 if (best.base == -1 || cur.len > best.len)
147 best = cur;
148 cur.base = -1;
149 }
150 }
151 }
152 if (cur.base != -1) {
153 if (best.base == -1 || cur.len > best.len)
154 best = cur;
155 }
156 if (best.base != -1 && best.len < 2)
157 best.base = -1;
158
159 /*
160 * Format the result.
161 */
162 tp = tmp;
163 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
164 /* Are we inside the best run of 0x00's? */
165 if (best.base != -1 && i >= best.base &&
166 i < (best.base + best.len)) {
167 if (i == best.base)
168 *tp++ = ':';
169 continue;
170 }
171 /* Are we following an initial run of 0x00s or any real hex? */
172 if (i != 0)
173 *tp++ = ':';
174 /* Is this address an encapsulated IPv4? */
175 if (i == 6 && best.base == 0 &&
176 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
177 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
178 return (NULL);
179 tp += strlen(tp);
180 break;
181 }
182 tp += sprintf(tp, "%x", words[i]);
183 }
184 /* Was it a trailing run of 0x00's? */
185 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ))
186 *tp++ = ':';
187 *tp++ = '\0';
188
189 /*
190 * Check for overflow, copy, and we're done.
191 */
192 if ((size_t)(tp - tmp) > size) {
193 errno = ENOSPC;
194 return (NULL);
195 }
196 strcpy(dst, tmp);
197 return (dst);
198 }