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1 /* inet_XtoX.c
2 * Simple implementation of the following functions:
3 * inet_ntop(), inet_ntoa(), inet_pton(), inet_aton().
4 *
5 * Differences from traditional implementaitons:
6 * o modifies destination buffers even on error return.
7 * o no fancy (hex, or 1.2) input support in inet_aton()
8 * o inet_aton() does not accept junk after an IP address.
9 * o inet_ntop(AF_INET) requires at least 16 bytes in dest,
10 * and inet_ntop(AF_INET6) at least 40 bytes
11 * (traditional inet_ntop() will try to fit anyway)
12 *
13 * Compile with -Dinet_XtoX_prefix=pfx_ to have pfx_*() instead of inet_*()
14 * Compile with -Dinet_XtoX_no_ntop or -Dinet_XtoX_no_pton
15 * to disable net2str or str2net conversions.
16 *
17 * #define inet_XtoX_prototypes and #include "this_file.c"
18 * to get function prototypes only (but not for inet_ntoa()).
19 * #define inet_XtoX_decl to be `static' for static visibility,
20 * or use __declspec(dllexport) or somesuch...
21 *
22 * Compile with -DTEST to test against stock implementation.
23 *
24 * Written by Michael Tokarev. Public domain.
25 */
26
27 #ifdef inet_XtoX_prototypes
28
29 struct in_addr;
30
31 #else
32
33 #include <errno.h>
34
35 #ifdef TEST
36
37 # include <netinet/in.h>
38 # include <sys/socket.h>
39 # include <arpa/inet.h>
40 # include <stdio.h>
41 # include <stdlib.h>
42 # include <unistd.h>
43 # include <string.h>
44 # undef inet_XtoX_prefix
45 # define inet_XtoX_prefix mjt_inet_
46 # undef inet_XtoX_no_ntop
47 # undef inet_XtoX_no_pton
48
49 #else /* !TEST */
50
51 struct in_addr { /* declare it here to avoid messing with headers */
52 unsigned char x[4];
53 };
54
55 #endif /* TEST */
56
57 #endif /* inet_XtoX_prototypes */
58
59 #ifndef inet_XtoX_prefix
60 # define inet_XtoX_prefix inet_
61 #endif
62 #ifndef inet_XtoX_decl
63 # define inet_XtoX_decl /*empty*/
64 #endif
65
66 #define cc2_(x,y) cc2__(x,y)
67 #define cc2__(x,y) x##y
68 #define fn(x) cc2_(inet_XtoX_prefix,x)
69
70 #ifndef inet_XtoX_no_ntop
71
72 inet_XtoX_decl const char *
73 fn(ntop)(int af, const void *src, char *dst, unsigned size);
74
75 #ifndef inet_XtoX_prototypes
76
77 static int mjt_ntop4(const void *_src, char *dst, int size) {
78 unsigned i, x, r;
79 char *p;
80 const unsigned char *s = _src;
81 if (size < 4*4) /* for simplicity, disallow non-max-size buffer */
82 return 0;
83 for (i = 0, p = dst; i < 4; ++i) {
84 if (i) *p++ = '.';
85 x = r = s[i];
86 if (x > 99) { *p++ = (char)(r / 100 + '0'); r %= 100; }
87 if (x > 9) { *p++ = (char)(r / 10 + '0'); r %= 10; }
88 *p++ = (char)(r + '0');
89 }
90 *p = '\0';
91 return 1;
92 }
93
94 static char *hexc(char *p, unsigned x) {
95 static char hex[16] = "0123456789abcdef";
96 if (x > 0x0fff) *p++ = hex[(x >>12) & 15];
97 if (x > 0x00ff) *p++ = hex[(x >> 8) & 15];
98 if (x > 0x000f) *p++ = hex[(x >> 4) & 15];
99 *p++ = hex[x & 15];
100 return p;
101 }
102
103 static int mjt_ntop6(const void *_src, char *dst, int size) {
104 unsigned i;
105 unsigned short w[8];
106 unsigned bs = 0, cs = 0;
107 unsigned bl = 0, cl = 0;
108 char *p;
109 const unsigned char *s = _src;
110
111 if (size < 40) /* for simplicity, disallow non-max-size buffer */
112 return 0;
113
114 for(i = 0; i < 8; ++i, s += 2) {
115 w[i] = (((unsigned short)(s[0])) << 8) | s[1];
116 if (!w[i]) {
117 if (!cl++) cs = i;
118 }
119 else {
120 if (cl > bl) bl = cl, bs = cs;
121 }
122 }
123 if (cl > bl) bl = cl, bs = cs;
124 p = dst;
125 if (bl == 1)
126 bl = 0;
127 if (bl) {
128 for(i = 0; i < bs; ++i) {
129 if (i) *p++ = ':';
130 p = hexc(p, w[i]);
131 }
132 *p++ = ':';
133 i += bl;
134 if (i == 8)
135 *p++ = ':';
136 }
137 else
138 i = 0;
139 for(; i < 8; ++i) {
140 if (i) *p++ = ':';
141 if (i == 6 && !bs && (bl == 6 || (bl == 5 && w[5] == 0xffff)))
142 return mjt_ntop4(s - 4, p, size - (p - dst));
143 p = hexc(p, w[i]);
144 }
145 *p = '\0';
146 return 1;
147 }
148
149 inet_XtoX_decl const char *
150 fn(ntop)(int af, const void *src, char *dst, unsigned size) {
151 switch(af) {
152 /* don't use AF_*: don't mess with headers */
153 case 2: /* AF_INET */ if (mjt_ntop4(src, dst, size)) return dst; break;
154 case 10: /* AF_INET6 */ if (mjt_ntop6(src, dst, size)) return dst; break;
155 default: errno = EAFNOSUPPORT; return (char*)0;
156 }
157 errno = ENOSPC;
158 return (char*)0;
159 }
160
161 inet_XtoX_decl const char *
162 fn(ntoa)(struct in_addr addr) {
163 static char buf[4*4];
164 mjt_ntop4(&addr, buf, sizeof(buf));
165 return buf;
166 }
167
168 #endif /* inet_XtoX_prototypes */
169 #endif /* inet_XtoX_no_ntop */
170
171 #ifndef inet_XtoX_no_pton
172
173 inet_XtoX_decl int fn(pton)(int af, const char *src, void *dst);
174 inet_XtoX_decl int fn(aton)(const char *src, struct in_addr *addr);
175
176 #ifndef inet_XtoX_prototypes
177
178 static int mjt_pton4(const char *c, void *dst) {
179 unsigned char *a = dst;
180 unsigned n, o;
181 for (n = 0; n < 4; ++n) {
182 if (*c < '0' || *c > '9')
183 return 0;
184 o = *c++ - '0';
185 while(*c >= '0' && *c <= '9')
186 if ((o = o * 10 + (*c++ - '0')) > 255)
187 return 0;
188 if (*c++ != (n == 3 ? '\0' : '.'))
189 return 0;
190 *a++ = (unsigned char)o;
191 }
192 return 1;
193 }
194
195 static int mjt_pton6(const char *c, void *dst) {
196 unsigned short w[8], *a = w, *z, *i;
197 unsigned v, o;
198 const char *sc;
199 unsigned char *d = dst;
200 if (*c != ':') z = (unsigned short*)0;
201 else if (*++c != ':') return 0;
202 else ++c, z = a;
203 i = 0;
204 for(;;) {
205 v = 0;
206 sc = c;
207 for(;;) {
208 if (*c >= '0' && *c <= '9') o = *c - '0';
209 else if (*c >= 'a' && *c <= 'f') o = *c - 'a' + 10;
210 else if (*c >= 'A' && *c <= 'F') o = *c - 'A' + 10;
211 else break;
212 v = (v << 4) | o;
213 if (v > 0xffff) return 0;
214 ++c;
215 }
216 if (sc == c) {
217 if (z == a && !*c)
218 break;
219 else
220 return 0;
221 }
222 if (*c == ':') {
223 if (a >= w + 8)
224 return 0;
225 *a++ = v;
226 if (*++c == ':') {
227 if (z)
228 return 0;
229 z = a;
230 if (!*++c)
231 break;
232 }
233 }
234 else if (!*c) {
235 if (a >= w + 8)
236 return 0;
237 *a++ = v;
238 break;
239 }
240 else if (*c == '.') {
241 if (a > w + 6)
242 return 0;
243 if (!mjt_pton4(sc, d))
244 return 0;
245 *a++ = ((unsigned)(d[0]) << 8) | d[1];
246 *a++ = ((unsigned)(d[2]) << 8) | d[3];
247 break;
248 }
249 else
250 return 0;
251 }
252 v = w + 8 - a;
253 if ((v && !z) || (!v && z))
254 return 0;
255 for(i = w; ; ++i) {
256 if (i == z)
257 while(v--) { *d++ = '\0'; *d++ = '\0'; }
258 if (i >= a)
259 break;
260 *d++ = (unsigned char)((*i >> 8) & 255);
261 *d++ = (unsigned char)(*i & 255);
262 }
263 return 1;
264 }
265
266 inet_XtoX_decl int fn(pton)(int af, const char *src, void *dst) {
267 switch(af) {
268 /* don't use AF_*: don't mess with headers */
269 case 2 /* AF_INET */: return mjt_pton4(src, dst);
270 case 10 /* AF_INET6 */: return mjt_pton6(src, dst);
271 default: errno = EAFNOSUPPORT; return -1;
272 }
273 }
274
275 inet_XtoX_decl int fn(aton)(const char *src, struct in_addr *addr) {
276 return mjt_pton4(src, addr);
277 }
278
279 #endif /* inet_XtoX_prototypes */
280
281 #endif /* inet_XtoX_no_pton */
282
283 #ifdef TEST
284
285 int main(int argc, char **argv) {
286 int i;
287 char n0[16], n1[16];
288 char p0[64], p1[64];
289 int af = AF_INET;
290 int pl = sizeof(p0);
291 int r0, r1;
292 const char *s0, *s1;
293
294 while((i = getopt(argc, argv, "46a:p:")) != EOF) switch(i) {
295 case '4': af = AF_INET; break;
296 case '6': af = AF_INET6; break;
297 case 'a': case 'p': pl = atoi(optarg); break;
298 default: return 1;
299 }
300 for(i = optind; i < argc; ++i) {
301 char *a = argv[i];
302
303 printf("%s:\n", a);
304 r0 = inet_pton(af, a, n0);
305 printf(" p2n stock: %s\n",
306 (r0 < 0 ? "(notsupp)" : !r0 ? "(inval)" : fn(ntop)(af,n0,p0,sizeof(p0))));
307 r1 = fn(pton)(af, a, n1);
308 printf(" p2n this : %s\n",
309 (r1 < 0 ? "(notsupp)" : !r1 ? "(inval)" : fn(ntop)(af,n1,p1,sizeof(p1))));
310
311 if ((r0 > 0) != (r1 > 0) ||
312 (r0 > 0 && r1 > 0 && memcmp(n0, n1, af == AF_INET ? 4 : 16) != 0))
313 printf(" DIFFER!\n");
314
315 s0 = inet_ntop(af, n1, p0, pl);
316 printf(" n2p stock: %s\n", s0 ? s0 : "(inval)");
317 s1 = fn(ntop)(af, n1, p1, pl);
318 printf(" n2p this : %s\n", s1 ? s1 : "(inval)");
319 if ((s0 != 0) != (s1 != 0) ||
320 (s0 && s1 && strcmp(s0, s1) != 0))
321 printf(" DIFFER!\n");
322
323 }
324 return 0;
325 }
326
327 #endif /* TEST */