1 /*
2 * Copyright (c) 1996-1999 by Internet Software Consortium.
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
15 * SOFTWARE.
16 */
17
18 #include "mydnsutil.h"
19
20 #ifndef HAVE_INET_NTOP
21
22 #if defined(LIBC_SCCS) && !defined(lint)
23 static const char rcsid[] = "$BINDId: inet_ntop.c,v 1.8 1999/10/13 16:39:28 vixie Exp $";
24 #endif /* LIBC_SCCS and not lint */
25
26
27 #ifdef SPRINTF_CHAR
28 # define SPRINTF(x) strlen(sprintf/**/x)
29 #else
30 # define SPRINTF(x) ((size_t)sprintf x)
31 #endif
32
33 /*
34 * WARNING: Don't even consider trying to compile this on a system where
35 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
36 */
37
38 static const char *inet_ntop4 (const uchar *src, char *dst, unsigned int size);
39 static const char *inet_ntop6 (const uchar *src, char *dst, unsigned int size);
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 * author:
47 * Paul Vixie, 1996.
48 */
49 const char *
inet_ntop(af,src,dst,size)50 inet_ntop(af, src, dst, size)
51 int af;
52 const void *src;
53 char *dst;
54 unsigned int size;
55 {
56 switch (af) {
57 case AF_INET:
58 return (inet_ntop4(src, dst, size));
59 case AF_INET6:
60 return (inet_ntop6(src, dst, size));
61 default:
62 errno = EAFNOSUPPORT;
63 return (NULL);
64 }
65 /* NOTREACHED */
66 }
67
68 /* const char *
69 * inet_ntop4(src, dst, size)
70 * format an IPv4 address
71 * return:
72 * `dst' (as a const)
73 * notes:
74 * (1) uses no statics
75 * (2) takes a uchar* not an in_addr as input
76 * author:
77 * Paul Vixie, 1996.
78 */
79 static const char *
inet_ntop4(src,dst,size)80 inet_ntop4(src, dst, size)
81 const uchar *src;
82 char *dst;
83 unsigned int size;
84 {
85 static const char fmt[] = "%u.%u.%u.%u";
86 char tmp[sizeof "255.255.255.255"];
87
88 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) > size) {
89 errno = ENOSPC;
90 return (NULL);
91 }
92 return strcpy(dst, tmp);
93 }
94
95 /* const char *
96 * inet_ntop6(src, dst, size)
97 * convert IPv6 binary address into presentation (printable) format
98 * author:
99 * Paul Vixie, 1996.
100 */
101 static const char *
inet_ntop6(src,dst,size)102 inet_ntop6(src, dst, size)
103 const uchar *src;
104 char *dst;
105 unsigned int size;
106 {
107 /*
108 * Note that int32_t and int16_t need only be "at least" large enough
109 * to contain a value of the specified size. On some systems, like
110 * Crays, there is no such thing as an integer variable with 16 bits.
111 * Keep this in mind if you think this function should have been coded
112 * to use pointer overlays. All the world's not a VAX.
113 */
114 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
115 struct { int base, len; } best, cur;
116 unsigned int words[16 / sizeof(uint16_t)];
117 int i;
118
119 /*
120 * Preprocess:
121 * Copy the input (bytewise) array into a wordwise array.
122 * Find the longest run of 0x00's in src[] for :: shorthanding.
123 */
124 memset(words, '\0', sizeof words);
125 for (i = 0; i < 16; i += 2)
126 words[i / 2] = (src[i] << 8) | src[i + 1];
127 best.base = -1;
128 cur.base = -1;
129 for (i = 0; i < (16 / sizeof(uint16_t)); i++) {
130 if (words[i] == 0) {
131 if (cur.base == -1)
132 cur.base = i, cur.len = 1;
133 else
134 cur.len++;
135 } else {
136 if (cur.base != -1) {
137 if (best.base == -1 || cur.len > best.len)
138 best = cur;
139 cur.base = -1;
140 }
141 }
142 }
143 if (cur.base != -1) {
144 if (best.base == -1 || cur.len > best.len)
145 best = cur;
146 }
147 if (best.base != -1 && best.len < 2)
148 best.base = -1;
149
150 /*
151 * Format the result.
152 */
153 tp = tmp;
154 for (i = 0; i < (16 / sizeof(uint16_t)); i++) {
155 /* Are we inside the best run of 0x00's? */
156 if (best.base != -1 && i >= best.base &&
157 i < (best.base + best.len)) {
158 if (i == best.base)
159 *tp++ = ':';
160 continue;
161 }
162 /* Are we following an initial run of 0x00s or any real hex? */
163 if (i != 0)
164 *tp++ = ':';
165 /* Is this address an encapsulated IPv4? */
166 if (i == 6 && best.base == 0 &&
167 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
168 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
169 return (NULL);
170 tp += strlen(tp);
171 break;
172 }
173 tp += SPRINTF((tp, "%x", words[i]));
174 }
175 /* Was it a trailing run of 0x00's? */
176 if (best.base != -1 && (best.base + best.len) ==
177 (16 / sizeof(uint16_t)))
178 *tp++ = ':';
179 *tp++ = '\0';
180
181 /*
182 * Check for overflow, copy, and we're done.
183 */
184 if ((unsigned int)(tp - tmp) > size) {
185 errno = ENOSPC;
186 return (NULL);
187 }
188 return strcpy(dst, tmp);
189 }
190
191 #endif /* !HAVE_INET_NTOP */
192