ip字符串转换成网络字节续的int型 inet_aton 源代码

int
inet_aton(const char *cp, struct in_addr *ap)
{
int dots = 0;
register u_long acc = 0, addr = 0;

do {
register char cc = *cp;

switch (cc) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
acc = acc * 10 + (cc - '0');
break;

case '.':
if (++dots > 3) {
return 0;
}
// Fall through

case '/0':
if (acc > 255) {
return 0;
}
addr = addr << 8 | acc;
acc = 0;
break;

default:
return 0;
}
} while (*cp++) ;

// Normalize the address
if (dots < 3) {
addr <<= 8 * (3 - dots) ;
}

//Store it if requested
if (ap) {
ap->s_addr = htonl(addr);
}

return 1;
}