1 /*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996-1999 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 #include <sys/param.h>
19 #include <sys/socket.h>
20 #include <sys/systm.h>
21
22 #include <netinet/in.h>
23
24 /*%
25 * WARNING: Don't even consider trying to compile this on a system where
26 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
27 */
28
29 static char *inet_ntop4(const u_char *src, char *dst, socklen_t size);
30 static char *inet_ntop6(const u_char *src, char *dst, socklen_t size);
31
32 /* char *
33 * inet_ntop(af, src, dst, size)
34 * convert a network format address to presentation format.
35 * return:
36 * pointer to presentation format address (`dst'), or NULL (see errno).
37 * author:
38 * Paul Vixie, 1996.
39 */
40 char *
inet_ntop(int af,const void * src,char * dst,socklen_t size)41 inet_ntop(int af, const void *src, char *dst, socklen_t size)
42 {
43 switch (af) {
44 case AF_INET:
45 return (inet_ntop4(src, dst, size));
46 case AF_INET6:
47 return (inet_ntop6(src, dst, size));
48 default:
49 return (NULL);
50 }
51 /* NOTREACHED */
52 }
53
54 /* const char *
55 * inet_ntop4(src, dst, size)
56 * format an IPv4 address
57 * return:
58 * `dst' (as a const)
59 * notes:
60 * (1) uses no statics
61 * (2) takes a u_char* not an in_addr as input
62 * author:
63 * Paul Vixie, 1996.
64 */
65 static char *
inet_ntop4(const u_char * src,char * dst,socklen_t size)66 inet_ntop4(const u_char *src, char *dst, socklen_t size)
67 {
68 static const char fmt[] = "%u.%u.%u.%u";
69 char tmp[sizeof "255.255.255.255"];
70 int l;
71
72 l = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
73 if (l <= 0 || (socklen_t) l >= size) {
74 return (NULL);
75 }
76 strlcpy(dst, tmp, size);
77 return (dst);
78 }
79
80 /* const char *
81 * inet_ntop6(src, dst, size)
82 * convert IPv6 binary address into presentation (printable) format
83 * author:
84 * Paul Vixie, 1996.
85 */
86 static char *
inet_ntop6(const u_char * src,char * dst,socklen_t size)87 inet_ntop6(const u_char *src, char *dst, socklen_t size)
88 {
89 /*
90 * Note that int32_t and int16_t need only be "at least" large enough
91 * to contain a value of the specified size. On some systems, like
92 * Crays, there is no such thing as an integer variable with 16 bits.
93 * Keep this in mind if you think this function should have been coded
94 * to use pointer overlays. All the world's not a VAX.
95 */
96 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
97 struct { int base, len; } best, cur;
98 #define NS_IN6ADDRSZ 16
99 #define NS_INT16SZ 2
100 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
101 int i;
102
103 /*
104 * Preprocess:
105 * Copy the input (bytewise) array into a wordwise array.
106 * Find the longest run of 0x00's in src[] for :: shorthanding.
107 */
108 memset(words, '\0', sizeof words);
109 for (i = 0; i < NS_IN6ADDRSZ; i++)
110 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
111 best.base = -1;
112 best.len = 0;
113 cur.base = -1;
114 cur.len = 0;
115 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
116 if (words[i] == 0) {
117 if (cur.base == -1)
118 cur.base = i, cur.len = 1;
119 else
120 cur.len++;
121 } else {
122 if (cur.base != -1) {
123 if (best.base == -1 || cur.len > best.len)
124 best = cur;
125 cur.base = -1;
126 }
127 }
128 }
129 if (cur.base != -1) {
130 if (best.base == -1 || cur.len > best.len)
131 best = cur;
132 }
133 if (best.base != -1 && best.len < 2)
134 best.base = -1;
135
136 /*
137 * Format the result.
138 */
139 tp = tmp;
140 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
141 /* Are we inside the best run of 0x00's? */
142 if (best.base != -1 && i >= best.base &&
143 i < (best.base + best.len)) {
144 if (i == best.base)
145 *tp++ = ':';
146 continue;
147 }
148 /* Are we following an initial run of 0x00s or any real hex? */
149 if (i != 0)
150 *tp++ = ':';
151 /* Is this address an encapsulated IPv4? */
152 if (i == 6 && best.base == 0 && (best.len == 6 ||
153 (best.len == 7 && words[7] != 0x0001) ||
154 (best.len == 5 && words[5] == 0xffff))) {
155 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
156 return (NULL);
157 tp += strlen(tp);
158 break;
159 }
160 tp += sprintf(tp, "%x", words[i]);
161 }
162 /* Was it a trailing run of 0x00's? */
163 if (best.base != -1 && (best.base + best.len) ==
164 (NS_IN6ADDRSZ / NS_INT16SZ))
165 *tp++ = ':';
166 *tp++ = '\0';
167
168 /*
169 * Check for overflow, copy, and we're done.
170 */
171 if ((socklen_t)(tp - tmp) > size) {
172 return (NULL);
173 }
174 strcpy(dst, tmp);
175 return (dst);
176 }
177
178 /*! \file */
179