2 * Simple implementation of the following functions:
3 * inet_ntop(), inet_ntoa(), inet_pton(), inet_aton().
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)
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.
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...
22 * Compile with -DTEST to test against stock implementation.
24 * Written by Michael Tokarev. Public domain.
27 #ifdef inet_XtoX_prototypes
37 # include <netinet/in.h>
38 # include <sys/socket.h>
39 # include <arpa/inet.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
51 struct in_addr { /* declare it here to avoid messing with headers */
57 #endif /* inet_XtoX_prototypes */
59 #ifndef inet_XtoX_prefix
60 # define inet_XtoX_prefix inet_
62 #ifndef inet_XtoX_decl
63 # define inet_XtoX_decl /*empty*/
66 #define cc2_(x,y) cc2__(x,y)
67 #define cc2__(x,y) x##y
68 #define fn(x) cc2_(inet_XtoX_prefix,x)
70 #ifndef inet_XtoX_no_ntop
72 inet_XtoX_decl const char *
73 fn(ntop)(int af, const void *src, char *dst, unsigned size);
75 #ifndef inet_XtoX_prototypes
77 static int mjt_ntop4(const void *_src, char *dst, int size) {
80 const unsigned char *s = _src;
81 if (size < 4*4) /* for simplicity, disallow non-max-size buffer */
83 for (i = 0, p = dst; i < 4; ++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');
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];
103 static int mjt_ntop6(const void *_src, char *dst, int size) {
106 unsigned bs = 0, cs = 0;
107 unsigned bl = 0, cl = 0;
109 const unsigned char *s = _src;
111 if (size < 40) /* for simplicity, disallow non-max-size buffer */
114 for(i = 0; i < 8; ++i, s += 2) {
115 w[i] = (((unsigned short)(s[0])) << 8) | s[1];
120 if (cl > bl) bl = cl, bs = cs;
123 if (cl > bl) bl = cl, bs = cs;
128 for(i = 0; i < bs; ++i) {
141 if (i == 6 && !bs && (bl == 6 || (bl == 5 && w[5] == 0xffff)))
142 return mjt_ntop4(s - 4, p, size - (p - dst));
149 inet_XtoX_decl const char *
150 fn(ntop)(int af, const void *src, char *dst, unsigned size) {
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;
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));
168 #endif /* inet_XtoX_prototypes */
169 #endif /* inet_XtoX_no_ntop */
171 #ifndef inet_XtoX_no_pton
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);
176 #ifndef inet_XtoX_prototypes
178 static int mjt_pton4(const char *c, void *dst) {
179 unsigned char *a = dst;
181 for (n = 0; n < 4; ++n) {
182 if (*c < '0' || *c > '9')
185 while(*c >= '0' && *c <= '9')
186 if ((o = o * 10 + (*c++ - '0')) > 255)
188 if (*c++ != (n == 3 ? '\0' : '.'))
190 *a++ = (unsigned char)o;
195 static int mjt_pton6(const char *c, void *dst) {
196 unsigned short w[8], *a = w, *z, *i;
199 unsigned char *d = dst;
200 if (*c != ':') z = (unsigned short*)0;
201 else if (*++c != ':') return 0;
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;
213 if (v > 0xffff) return 0;
240 else if (*c == '.') {
243 if (!mjt_pton4(sc, d))
245 *a++ = ((unsigned)(d[0]) << 8) | d[1];
246 *a++ = ((unsigned)(d[2]) << 8) | d[3];
253 if ((v && !z) || (!v && z))
257 while(v--) { *d++ = '\0'; *d++ = '\0'; }
260 *d++ = (unsigned char)((*i >> 8) & 255);
261 *d++ = (unsigned char)(*i & 255);
266 inet_XtoX_decl int fn(pton)(int af, const char *src, void *dst) {
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;
275 inet_XtoX_decl int fn(aton)(const char *src, struct in_addr *addr) {
276 return mjt_pton4(src, addr);
279 #endif /* inet_XtoX_prototypes */
281 #endif /* inet_XtoX_no_pton */
285 int main(int argc, char **argv) {
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;
300 for(i = optind; i < argc; ++i) {
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))));
311 if ((r0 > 0) != (r1 > 0) ||
312 (r0 > 0 && r1 > 0 && memcmp(n0, n1, af == AF_INET ? 4 : 16) != 0))
313 printf(" DIFFER!\n");
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");