inet_ntop.c: Work around GCC 4.6's detection of uninitialized variables
[git/dscho.git] / compat / inet_ntop.c
blob60b5a1d0f8262baca70247923a399fdb4ee3cac1
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 #include <errno.h>
19 #include <sys/types.h>
21 #include "../git-compat-util.h"
23 #include <stdio.h>
24 #include <string.h>
26 #ifndef NS_INADDRSZ
27 #define NS_INADDRSZ 4
28 #endif
29 #ifndef NS_IN6ADDRSZ
30 #define NS_IN6ADDRSZ 16
31 #endif
32 #ifndef NS_INT16SZ
33 #define NS_INT16SZ 2
34 #endif
37 * WARNING: Don't even consider trying to compile this on a system where
38 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
41 /* const char *
42 * inet_ntop4(src, dst, size)
43 * format an IPv4 address
44 * return:
45 * `dst' (as a const)
46 * notes:
47 * (1) uses no statics
48 * (2) takes a u_char* not an in_addr as input
49 * author:
50 * Paul Vixie, 1996.
52 static const char *
53 inet_ntop4(const u_char *src, char *dst, size_t size)
55 static const char fmt[] = "%u.%u.%u.%u";
56 char tmp[sizeof "255.255.255.255"];
57 int nprinted;
59 nprinted = snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]);
60 if (nprinted < 0)
61 return (NULL); /* we assume "errno" was set by "snprintf()" */
62 if ((size_t)nprinted > size) {
63 errno = ENOSPC;
64 return (NULL);
66 strcpy(dst, tmp);
67 return (dst);
70 #ifndef NO_IPV6
71 /* const char *
72 * inet_ntop6(src, dst, size)
73 * convert IPv6 binary address into presentation (printable) format
74 * author:
75 * Paul Vixie, 1996.
77 static const char *
78 inet_ntop6(const u_char *src, char *dst, size_t size)
81 * Note that int32_t and int16_t need only be "at least" large enough
82 * to contain a value of the specified size. On some systems, like
83 * Crays, there is no such thing as an integer variable with 16 bits.
84 * Keep this in mind if you think this function should have been coded
85 * to use pointer overlays. All the world's not a VAX.
87 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"], *tp;
88 struct { int base, len; } best, cur;
89 unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
90 int i;
93 * Preprocess:
94 * Copy the input (bytewise) array into a wordwise array.
95 * Find the longest run of 0x00's in src[] for :: shorthanding.
97 memset(words, '\0', sizeof words);
98 for (i = 0; i < NS_IN6ADDRSZ; i++)
99 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
100 best.base = -1;
101 best.len = 0;
102 cur.base = -1;
103 cur.len = 0;
104 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
105 if (words[i] == 0) {
106 if (cur.base == -1)
107 cur.base = i, cur.len = 1;
108 else
109 cur.len++;
110 } else {
111 if (cur.base != -1) {
112 if (best.base == -1 || cur.len > best.len)
113 best = cur;
114 cur.base = -1;
118 if (cur.base != -1) {
119 if (best.base == -1 || cur.len > best.len)
120 best = cur;
122 if (best.base != -1 && best.len < 2)
123 best.base = -1;
126 * Format the result.
128 tp = tmp;
129 for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
130 /* Are we inside the best run of 0x00's? */
131 if (best.base != -1 && i >= best.base &&
132 i < (best.base + best.len)) {
133 if (i == best.base)
134 *tp++ = ':';
135 continue;
137 /* Are we following an initial run of 0x00s or any real hex? */
138 if (i != 0)
139 *tp++ = ':';
140 /* Is this address an encapsulated IPv4? */
141 if (i == 6 && best.base == 0 &&
142 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
143 if (!inet_ntop4(src+12, tp, sizeof tmp - (tp - tmp)))
144 return (NULL);
145 tp += strlen(tp);
146 break;
148 tp += snprintf(tp, sizeof tmp - (tp - tmp), "%x", words[i]);
150 /* Was it a trailing run of 0x00's? */
151 if (best.base != -1 && (best.base + best.len) ==
152 (NS_IN6ADDRSZ / NS_INT16SZ))
153 *tp++ = ':';
154 *tp++ = '\0';
157 * Check for overflow, copy, and we're done.
159 if ((size_t)(tp - tmp) > size) {
160 errno = ENOSPC;
161 return (NULL);
163 strcpy(dst, tmp);
164 return (dst);
166 #endif
168 /* char *
169 * inet_ntop(af, src, dst, size)
170 * convert a network format address to presentation format.
171 * return:
172 * pointer to presentation format address (`dst'), or NULL (see errno).
173 * author:
174 * Paul Vixie, 1996.
176 const char *
177 inet_ntop(int af, const void *src, char *dst, size_t size)
179 switch (af) {
180 case AF_INET:
181 return (inet_ntop4(src, dst, size));
182 #ifndef NO_IPV6
183 case AF_INET6:
184 return (inet_ntop6(src, dst, size));
185 #endif
186 default:
187 errno = EAFNOSUPPORT;
188 return (NULL);
190 /* NOTREACHED */