1 /* $OpenBSD: inet_ntop.c,v 1.4 2016/09/04 17:05:24 claudio 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
19 #include <sys/param.h>
20 #include <sys/systm.h>
21 #include <sys/socket.h>
22
23 #include <netinet/in.h>
24
25 #define IN6ADDRSZ 16
26 #define INT16SZ 2
27
28 /*
29 * WARNING: Don't even consider trying to compile this on a system where
30 * sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
31 */
32
33 static const char *inet_ntop4(const u_char *src, char *dst, size_t size);
34 #ifdef INET6
35 static const char *inet_ntop6(const u_char *src, char *dst, size_t size);
36 #endif /* INET6 */
37
38 /* char *
39 * inet_ntop(af, src, dst, size)
40 * convert a network format address to presentation format.
41 * return:
42 * pointer to presentation format address (`dst'), or NULL (see errno).
43 * author:
44 * Paul Vixie, 1996.
45 */
46 const char *
inet_ntop(int af,const void * src,char * dst,socklen_t size)47 inet_ntop(int af, const void *src, char *dst, socklen_t size)
48 {
49 switch (af) {
50 case AF_INET:
51 return (inet_ntop4(src, dst, (size_t)size));
52 #ifdef INET6
53 case AF_INET6:
54 return (inet_ntop6(src, dst, (size_t)size));
55 #endif /* INET6 */
56 default:
57 return (NULL);
58 }
59 /* NOTREACHED */
60 }
61
62 const char *
sockaddr_ntop(struct sockaddr * sa,char * dst,size_t size)63 sockaddr_ntop(struct sockaddr *sa, char *dst, size_t size)
64 {
65 u_int8_t l;
66 size_t n;
67
68 if (sa->sa_len < 2)
69 return "bad sa";
70 switch (sa->sa_family) {
71 case AF_INET:
72 return inet_ntop4((u_char *)&satosin(sa)->sin_addr, dst, size);
73 #ifdef INET6
74 case AF_INET6:
75 return inet_ntop6((u_char *)&satosin6(sa)->sin6_addr, dst, size);
76 #endif
77 default:
78 n = snprintf(dst, size, "%d ", sa->sa_family);
79 for (l = 0; l < sa->sa_len - offsetof(struct sockaddr, sa_data); l++) {
80 int r = snprintf(dst + n, size - n, "%02x", sa->sa_data[l]);
81 if (r == -1)
82 return "bad sa";
83 n += r;
84 if (n > size)
85 n = size;
86 }
87 return (dst);
88 }
89 }
90
91 /* const char *
92 * inet_ntop4(src, dst, size)
93 * format an IPv4 address, more or less like inet_ntoa()
94 * return:
95 * `dst' (as a const)
96 * notes:
97 * (1) uses no statics
98 * (2) takes a u_char* not an in_addr as input
99 * author:
100 * Paul Vixie, 1996.
101 */
102 static const char *
inet_ntop4(const u_char * src,char * dst,size_t size)103 inet_ntop4(const u_char *src, char *dst, size_t size)
104 {
105 char tmp[sizeof "255.255.255.255"];
106 int l;
107
108 l = snprintf(tmp, sizeof(tmp), "%u.%u.%u.%u",
109 src[0], src[1], src[2], src[3]);
110 if (l <= 0 || l >= size) {
111 return (NULL);
112 }
113 strlcpy(dst, tmp, size);
114 return (dst);
115 }
116
117 #ifdef INET6
118 /* const char *
119 * inet_ntop6(src, dst, size)
120 * convert IPv6 binary address into presentation (printable) format
121 * author:
122 * Paul Vixie, 1996.
123 */
124 static const char *
inet_ntop6(const u_char * src,char * dst,size_t size)125 inet_ntop6(const u_char *src, char *dst, size_t size)
126 {
127 /*
128 * Note that int32_t and int16_t need only be "at least" large enough
129 * to contain a value of the specified size. On some systems, like
130 * Crays, there is no such thing as an integer variable with 16 bits.
131 * Keep this in mind if you think this function should have been coded
132 * to use pointer overlays. All the world's not a VAX.
133 */
134 char tmp[sizeof "ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255"];
135 char *tp, *ep;
136 struct { int base, len; } best, cur;
137 u_int words[IN6ADDRSZ / INT16SZ];
138 int i;
139 int advance;
140
141 /*
142 * Preprocess:
143 * Copy the input (bytewise) array into a wordwise array.
144 * Find the longest run of 0x00's in src[] for :: shorthanding.
145 */
146 memset(words, '\0', sizeof words);
147 for (i = 0; i < IN6ADDRSZ; i++)
148 words[i / 2] |= (src[i] << ((1 - (i % 2)) << 3));
149 best.base = -1;
150 cur.base = -1;
151 for (i = 0; i < (IN6ADDRSZ / INT16SZ); i++) {
152 if (words[i] == 0) {
153 if (cur.base == -1)
154 cur.base = i, cur.len = 1;
155 else
156 cur.len++;
157 } else {
158 if (cur.base != -1) {
159 if (best.base == -1 || cur.len > best.len)
160 best = cur;
161 cur.base = -1;
162 }
163 }
164 }
165 if (cur.base != -1) {
166 if (best.base == -1 || cur.len > best.len)
167 best = cur;
168 }
169 if (best.base != -1 && best.len < 2)
170 best.base = -1;
171
172 /*
173 * Format the result.
174 */
175 tp = tmp;
176 ep = tmp + sizeof(tmp);
177 for (i = 0; i < (IN6ADDRSZ / INT16SZ) && tp < ep; i++) {
178 /* Are we inside the best run of 0x00's? */
179 if (best.base != -1 && i >= best.base &&
180 i < (best.base + best.len)) {
181 if (i == best.base) {
182 if (tp + 1 >= ep)
183 return (NULL);
184 *tp++ = ':';
185 }
186 continue;
187 }
188 /* Are we following an initial run of 0x00s or any real hex? */
189 if (i != 0) {
190 if (tp + 1 >= ep)
191 return (NULL);
192 *tp++ = ':';
193 }
194 /* Is this address an encapsulated IPv4? */
195 if (i == 6 && best.base == 0 &&
196 (best.len == 6 || (best.len == 5 && words[5] == 0xffff))) {
197 if (!inet_ntop4(src+12, tp, (size_t)(ep - tp)))
198 return (NULL);
199 tp += strlen(tp);
200 break;
201 }
202 advance = snprintf(tp, ep - tp, "%x", words[i]);
203 if (advance <= 0 || advance >= ep - tp)
204 return (NULL);
205 tp += advance;
206 }
207 /* Was it a trailing run of 0x00's? */
208 if (best.base != -1 && (best.base + best.len) == (IN6ADDRSZ / INT16SZ)) {
209 if (tp + 1 >= ep)
210 return (NULL);
211 *tp++ = ':';
212 }
213 if (tp + 1 >= ep)
214 return (NULL);
215 *tp++ = '\0';
216
217 /*
218 * Check for overflow, copy, and we're done.
219 */
220 if ((size_t)(tp - tmp) > size) {
221 return (NULL);
222 }
223 strlcpy(dst, tmp, size);
224 return (dst);
225 }
226 #endif /* INET6 */
227