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inet_aton.c
114 lines (105 loc) · 2.26 KB
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inet_aton.c
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/*
inet_aton.c
Date Created: Thu Jan 20 20:46:16 2000
Author: Simon Leinen <simon.leinen@switch.ch>
This file implements the function inet_aton(), which converts a
string in dotted-quad notation to an IPv4 address (struct in_addr).
It should be able to cope with other historic formats with zero, one,
two or three dots too, although I'm not sure I got them all right.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
/* #define TEST 1 */
#ifdef TEST
#include <stdio.h>
#endif
static int inet_aton_1 (const char *, const char *, struct in_addr *);
extern int
inet_aton (const char *s, struct in_addr *out)
{
return inet_aton_1 (s, s+strlen (s), out);
}
static int
inet_aton_1 (const char *start, const char *end, struct in_addr *out)
{
long addr = 0;
unsigned long component[4], n;
unsigned ncomp, k;
const char *s;
for (s = start, ncomp = 0; s < end; ++s, component[ncomp++] = n)
{
for (n = 0; s < end && *s != '.'; ++s)
{
if (*s < '0' || *s > '9')
return 0;
n = n * 10 + (*s - '0');
}
}
if (ncomp == 0 || ncomp > 4)
return 0;
else
{
switch (ncomp)
{
case 1:
addr = component[0];
break;
case 2:
if (component[0] > 255 || component[1] > 16777215)
return 0;
addr = component[0] << 24 | component[1];
break;
case 3:
if (component[0] > 255 || component[1] > 255 || component[2] > 65535)
return 0;
addr = component[0] << 24 | component[1] << 16 | component[2];
break;
case 4:
for (k = 0; k < 4; ++k)
{
if (component[k] > 255)
return 0;
addr <<= 8;
addr |= component[k];
}
break;
default:
return 0;
}
out->s_addr = htonl (addr);
return 1;
}
}
#ifdef TEST
extern int
main (argc, argv)
int argc;
char **argv;
{
char buf[256];
int buflen = 256;
struct sockaddr_in addr;
while (1)
{
if (fgets (buf, buflen, stdin) == EOF)
{
break;
}
if (buf[strlen (buf)-1] == 10)
buf[strlen (buf)-1] = 0;
if (inet_aton (buf, &addr.sin_addr) == 0)
{
fprintf (stderr, "Conversion failed.\n");
}
else
{
printf ("-> %08lx [%s]\n",
(unsigned long) addr.sin_addr.s_addr,
inet_ntoa (addr.sin_addr));
}
}
return 0;
}
#endif /* TEST */