Use PTR_ALIGN_DOWN on strcspn and strspn
[glibc.git] / resolv / inet_ntop.c
blob32338c58b05b2138ebc4a300a28bcedf9a18684e
1 /*
2 * Copyright (c) 1996-1999 by Internet Software Consortium.
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.
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.
18 #if defined(LIBC_SCCS) && !defined(lint)
19 static const char rcsid[] = "$BINDId: inet_ntop.c,v 1.8 1999/10/13 16:39:28 vixie Exp $";
20 #endif /* LIBC_SCCS and not lint */
22 #include <sys/param.h>
23 #include <sys/types.h>
24 #include <sys/socket.h>
26 #include <netinet/in.h>
27 #include <arpa/inet.h>
28 #include <arpa/nameser.h>
30 #include <errno.h>
31 #include <stdio.h>
32 #include <string.h>
34 #ifdef SPRINTF_CHAR
35 # define SPRINTF(x) strlen(sprintf/**/x)
36 #else
37 # define SPRINTF(x) ((size_t)sprintf x)
38 #endif
41 * WARNING: Don't even consider trying to compile this on a system where
42 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
45 static const char *inet_ntop4 (const u_char *src, char *dst, socklen_t size)
46 internal_function;
47 static const char *inet_ntop6 (const u_char *src, char *dst, socklen_t size)
48 internal_function;
50 /* char *
51 * inet_ntop(af, src, dst, size)
52 * convert a network format address to presentation format.
53 * return:
54 * pointer to presentation format address (`dst'), or NULL (see errno).
55 * author:
56 * Paul Vixie, 1996.
58 const char *
59 inet_ntop (int af, const void *src, char *dst, socklen_t size)
61 switch (af) {
62 case AF_INET:
63 return (inet_ntop4(src, dst, size));
64 case AF_INET6:
65 return (inet_ntop6(src, dst, size));
66 default:
67 __set_errno (EAFNOSUPPORT);
68 return (NULL);
70 /* NOTREACHED */
72 libc_hidden_def (inet_ntop)
74 /* const char *
75 * inet_ntop4(src, dst, size)
76 * format an IPv4 address
77 * return:
78 * `dst' (as a const)
79 * notes:
80 * (1) uses no statics
81 * (2) takes a u_char* not an in_addr as input
82 * author:
83 * Paul Vixie, 1996.
85 static const char *
86 internal_function
87 inet_ntop4 (const u_char *src, char *dst, socklen_t size)
89 static const char fmt[] = "%u.%u.%u.%u";
90 char tmp[sizeof "255.255.255.255"];
92 if (SPRINTF((tmp, fmt, src[0], src[1], src[2], src[3])) >= size) {
93 __set_errno (ENOSPC);
94 return (NULL);
96 return strcpy(dst, tmp);
99 /* const char *
100 * inet_ntop6(src, dst, size)
101 * convert IPv6 binary address into presentation (printable) format
102 * author:
103 * Paul Vixie, 1996.
105 static const char *
106 internal_function
107 inet_ntop6 (const u_char *src, char *dst, socklen_t size)
110 * Note that int32_t and int16_t need only be "at least" large enough
111 * to contain a value of the specified size. On some systems, like
112 * Crays, there is no such thing as an integer variable with 16 bits.
113 * Keep this in mind if you think this function should have been coded
114 * to use pointer overlays. All the world's not a VAX.
116 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
117 struct { int base, len; } best, cur;
118 u_int words[NS_IN6ADDRSZ / NS_INT16SZ];
119 int i;
122 * Preprocess:
123 * Copy the input (bytewise) array into a wordwise array.
124 * Find the longest run of 0x00's in src[] for :: shorthanding.
126 memset(words, '\0', sizeof words);
127 for (i = 0; i < NS_IN6ADDRSZ; i += 2)
128 words[i / 2] = (src[i] << 8) | src[i + 1];
129 best.base = -1;
130 cur.base = -1;
131 best.len = 0;
132 cur.len = 0;
133 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
134 if (words[i] == 0) {
135 if (cur.base == -1)
136 cur.base = i, cur.len = 1;
137 else
138 cur.len++;
139 } else {
140 if (cur.base != -1) {
141 if (best.base == -1 || cur.len > best.len)
142 best = cur;
143 cur.base = -1;
147 if (cur.base != -1) {
148 if (best.base == -1 || cur.len > best.len)
149 best = cur;
151 if (best.base != -1 && best.len < 2)
152 best.base = -1;
155 * Format the result.
157 tp = tmp;
158 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
159 /* Are we inside the best run of 0x00's? */
160 if (best.base != -1 && i >= best.base &&
161 i < (best.base + best.len)) {
162 if (i == best.base)
163 *tp++ = ':';
164 continue;
166 /* Are we following an initial run of 0x00s or any real hex? */
167 if (i != 0)
168 *tp++ = ':';
169 /* Is this address an encapsulated IPv4? */
170 if (i == 6 && best.base == 0 &&
171 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
172 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
173 return (NULL);
174 tp += strlen(tp);
175 break;
177 tp += SPRINTF((tp, "%x", words[i]));
179 /* Was it a trailing run of 0x00's? */
180 if (best.base != -1 && (best.base + best.len) ==
181 (NS_IN6ADDRSZ / NS_INT16SZ))
182 *tp++ = ':';
183 *tp++ = '\0';
186 * Check for overflow, copy, and we're done.
188 if ((socklen_t)(tp - tmp) > size) {
189 __set_errno (ENOSPC);
190 return (NULL);
192 return strcpy(dst, tmp);