dot2ip.c

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/* dot2ip.c - dot2ip */

#include <xinu.h>

/*------------------------------------------------------------------------
 * dot2ip  -  Convert a string of dotted decimal to an unsigned integer
 *------------------------------------------------------------------------
 */
uint32  dot2ip (
      char   *dotted,       /* IP address in dotted decimal */
      uint32 *result        /* Location to which binary IP  */
                    /*    address will be stored    */
                    /*    (host byte order)     */
    )
{
    int32   seg;            /* Counts segments      */
    int32   nch;            /* Counts chars within segment  */
    char    ch;         /* Next character       */
    uint32  ipaddr;         /* IP address in binary     */
    int32   val;            /* Binary value of one segment  */

    /* Input must have the form  X.X.X.X, where X is 1 to 3 digits  */

    ipaddr = 0;
    for (seg=0 ; seg<4 ; seg++) {    /* For each segment        */
        val = 0;
        for (nch=0 ; nch<4; nch++) { /* Up to four chars per segment*/
        ch = *dotted++;
        if ( (ch==NULLCH) || (ch == '.') ) {
            if (nch == 0) {
                return SYSERR;
            } else {
                break;
            }
        }

        /*  Non-digit is an error */

        if ( (ch<'0') || (ch>'9') ) {
            return SYSERR;
        }

        val = 10*val + (ch-'0');
        }

        if (val > 255) {    /* Out of valid range */
        return SYSERR;
        }
        ipaddr = (ipaddr << 8) | val;

        if (ch == NULLCH) {
        break;
        }
    }
    if ( (seg != 3) || (ch != NULLCH) ) {
        return SYSERR;
    }
    *result = ipaddr;
    return OK;
}