getutime.c

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/* getutime.c - getutime */

#include <xinu.h>
#include <stdio.h>

/*------------------------------------------------------------------------
 * getutime  -  Obtain time in seconds past Jan 1, 1970, UCT (GMT)
 *------------------------------------------------------------------------
 */
status  getutime(
      uint32  *timvar       /* Location to store the result */
    )
{
    uint32  now;            /* Current time in xinu format  */
    int32   retval;         /* Return value from call   */
    uid32   slot;           /* Slot in UDP table        */
    struct  ntp {           /* Format of an NTP message */
        byte    livn;       /* LI:2 VN:3 and mode:3 fields  */
        byte    strat;      /* Stratum          */
        byte    poll;       /* Poll interval        */
        byte    precision;  /* Precision            */
        uint32  rootdelay;  /* Root delay           */
        uint32  rootdisp;   /* Root dispersion      */
        uint32  refid;      /* Reference identifier     */
        uint32  reftimestamp[2];/* Reference timestamp      */
        uint32  oritimestamp[2];/* Originate timestamp      */
        uint32  rectimestamp[2];/* Receive timestamp        */
        uint32  trntimestamp[2];/* Transmit timestamp       */
    } ntpmsg;

    if (Date.dt_bootvalid) {    /* Return time from local info  */
        *timvar = Date.dt_boot + clktime;
        return OK;
    }

    /* Verify that we have obtained an IP address */

    if (getlocalip() == SYSERR) {
        return SYSERR;
    }

    /* If the DHCP response did not contain an NTP server address   */
    /*  use the default server                  */

    if (NetData.ntpserver == 0) {
        if (dot2ip(TIMESERVER, &NetData.ntpserver) == SYSERR) {
            return SYSERR;
        }
    }

    /* Contact the time server to get the date and time */

    slot = udp_register(NetData.ntpserver, TIMERPORT, TIMELPORT);
    if (slot == SYSERR) {
        fprintf(stderr,"getutime: cannot register a udp port %d\n",
                    TIMERPORT);
        return SYSERR;
    }

    /* Send a request message to the NTP server */

    memset((char *)&ntpmsg, 0x00, sizeof(ntpmsg));
    ntpmsg.livn = 0x1b; /* Client request, protocol version 3 */
    retval = udp_send(slot, (char *)&ntpmsg, sizeof(ntpmsg));
    if (retval == SYSERR) {
        fprintf(stderr,"getutime: cannot send to the server\n");
        udp_release(slot);
        return SYSERR;
    }

    /* Read the response from the NTP server */

    retval = udp_recv(slot, (char *) &ntpmsg, sizeof(ntpmsg),
                             TIMETIMEOUT);
    if ( (retval == SYSERR) || (retval == TIMEOUT) ) {
        udp_release(slot);
        return SYSERR;
    }
    udp_release(slot);

    /* Extract the seconds since Jan 1900 and convert */

    now = ntim2xtim( ntohl(ntpmsg.trntimestamp[0]) );
    Date.dt_boot = now - clktime;
    Date.dt_bootvalid = TRUE;
    *timvar = now;
    return OK;
}