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/*

 * Synchronize with an NTP server

 *

 * This program may be distributed and used for any purpose.

 * I ask only that you:

 *      1. Leave this author information intact.

 *      2. Document any changes you make.

 *

 * W. Eric Norum

 * Canadian Light Source

 * University of Saskatchewan

 * Saskatoon, Saskatchewan, CANADA

 * eric@cls.usask.ca

 *

 *  $Id: rtems_bsdnet_ntp.c,v 1.2 2001-09-27 12:01:52 chris Exp $

 */

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <time.h>

#include <limits.h>

#include <rtems.h>

#include <rtems/rtems_bsdnet.h>

#include <rtems/error.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

/*

 * RTEMS base: 1988, January 1

 *  UNIX base: 1970, January 1

 *   NTP base: 1900, January 1

 */

#define UNIX_BASE_TO_NTP_BASE (((70UL*365UL)+17UL) * (24*60*60))

struct timestamp {

        rtems_unsigned32        integer;

        rtems_unsigned32        fraction;

};

struct ntpPacketSmall {

        rtems_unsigned8         li_vn_mode;

        rtems_unsigned8         stratum;

        rtems_signed8           poll_interval;

        rtems_signed8           precision;

        rtems_signed32          root_delay;

        rtems_signed32          root_dispersion;

        char                    reference_identifier[4];

        struct timestamp        reference_timestamp;

        struct timestamp        originate_timestamp;

        struct timestamp        receive_timestamp;

        struct timestamp        transmit_timestamp;

};

struct ntpPacket {

        struct ntpPacketSmall   ntp;

        char                    authenticator[96];

};

static int

processPacket (struct ntpPacketSmall *p)

{

        time_t tbuf;

        struct tm *lt;

        rtems_time_of_day rt;

        rtems_interval ticks_per_second;

        if (((p->li_vn_mode & (0x7 << 3)) != (3 << 3))

         || ((p->transmit_timestamp.integer == 0) && (p->transmit_timestamp.fraction == 0)))

                return 0;

        rtems_clock_get (RTEMS_CLOCK_GET_TICKS_PER_SECOND, &ticks_per_second);

        tbuf = ntohl (p->transmit_timestamp.integer) - UNIX_BASE_TO_NTP_BASE - rtems_bsdnet_timeoffset;

        lt = gmtime (&tbuf);

        rt.year = lt->tm_year + 1900;

        rt.month = lt->tm_mon + 1;

        rt.day = lt->tm_mday;

        rt.hour = lt->tm_hour;

        rt.minute = lt->tm_min;

        rt.second = lt->tm_sec;

        rt.ticks = ntohl (p->transmit_timestamp.fraction) / (ULONG_MAX / ticks_per_second);

        if (rt.ticks >= ticks_per_second)

                rt.ticks = ticks_per_second - 1;

        rtems_clock_set (&rt);

        return 1;

}

int

rtems_bsdnet_synchronize_ntp (int interval, rtems_task_priority priority)

{

        int s;

        int i;

        static struct sockaddr_in myAddr, farAddr;

        int fromlen;

        struct ntpPacketSmall packet;

        struct timeval tv;

        if (interval != 0) {

                printf ("Daemon-mode note yet supported.\n");

                errno = EINVAL;

                return -1;

        }

        s = socket (AF_INET, SOCK_DGRAM, 0);

        if (s < 0) {

                printf ("Can't create socket: %s\n", strerror (errno));

                return -1;

        }

        tv.tv_sec = 5;

        tv.tv_usec = 0;

        if (setsockopt (s, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv, sizeof tv) < 0) {

                printf ("Can't set socket receive timeout: %s", strerror (errno));

                return -1;

        }

        memset (&myAddr, 0, sizeof myAddr);

        myAddr.sin_family = AF_INET;

        myAddr.sin_port = htons (123);

        myAddr.sin_addr.s_addr = htonl (INADDR_ANY);

        if (bind (s, (struct sockaddr *)&myAddr, sizeof myAddr) < 0) {

                printf ("Can't bind socket: %s\n", strerror (errno));

                return -1;

        }

        for (;;) {

                /*

                 * If there's no server we just have to wait

                 * and hope that there's an NTP broadcast

                 * server out there somewhere.

                 */

                if (rtems_bsdnet_ntpserver_count > 0) {

                        memset (&farAddr, 0, sizeof farAddr);

                        farAddr.sin_family = AF_INET;

                        farAddr.sin_port = htons (123);

                        /*

                         * For now, try only the first server.

                         */

                        farAddr.sin_addr = rtems_bsdnet_ntpserver[0];

                        memset (&packet, 0, sizeof packet);

                        packet.li_vn_mode = (3 << 3) | 3; /* NTP version 3, client */

                        i = sendto (s, &packet, sizeof packet, 0, (struct sockaddr *)&farAddr, sizeof farAddr);

                        if (i != sizeof packet) {

                                printf ("Can't send: %s\n", strerror (errno));

                                return -1;

                        }

                }

                fromlen = sizeof farAddr;

                i = recvfrom (s, &packet, sizeof packet, 0, (struct sockaddr *)&farAddr, &fromlen);

                if (i == 0)

                        rtems_panic ("EOF");

                if (i < 0) {

                        if ((errno == EWOULDBLOCK) || (errno == EAGAIN))

                                continue;

                        rtems_panic ("Can't receive: %s", strerror (errno));

                }

                if (i >= sizeof packet) {

                        if (processPacket (&packet))

                                return 0;

                }

        }

}