usr/src/lib/libc/net/inet_addr.c

/*      inet_addr.c     4.2     82/10/05        */

#include <sys/types.h>
#include <ctype.h>

/*
 * Internet address interpretation routine.
 * All the network library routines call this
 * routine to interpret entries in the data bases
 * which are expected to be an address.
 */
u_long
inet_addr(cp)
        register char *cp;
{
        register unsigned long val, base, n;
        register char c;
        unsigned long parts[4], *pp = parts;

again:
        val = 0; base = 10;
        if (*cp == '0')
                base = 8, cp++;
        if (*cp == 'x' || *cp == 'X')
                base = 16, cp++;
        while (c = *cp) {
                if (isdigit(c)) {
                        val = (val * base) + (c - '0');
                        cp++;
                        continue;
                }
                if (base == 16 && isxdigit(c)) {
                        val = (val << 4) + (c + 10 - (islower(c) ? 'a' : 'A'));
                        cp++;
                        continue;
                }
                break;
        }
        if (*cp == '.') {
                /*
                 * Internet format:
                 *      a.b.c.d
                 *      a.b.c   (with c treated as 16-bits)
                 *      a.b     (with b treated as 24 bits)
                 */
                if (pp >= parts + 4)
                        return (-1);
                *pp++ = val, cp++;
                goto again;
        }
        if (*cp && !isspace(*cp))
                return (-1);
        n = pp - parts;
        if (n > 0) {
                if (n > 4)
                        return (-1);
                *pp++ = val; n++;
                val = parts[0];
                if (n > 1)
                        val <<= 24;
                if (n > 2)
                        val |= (parts[1] & 0xff) << 16;
                if (n > 3)
                        val |= (parts[2] & 0xff) << 8;
                if (n > 1)
                        val |= parts[n - 1];
#if vax || pdp11
                val = htonl(val);
#endif
        }
        return (val);
}