source: rtems/cpukit/libnetworking/lib/rtems_bsdnet_ntp.c @ 8d2733f

/*
 * 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
 *
 *  $Id$
 */

#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 ntpPacket {
        struct ntpPacketSmall   ntp;
        char                    authenticator[96];
};

static int
processPacket (struct ntpPacketSmall *p, int state, void *unused)
{
        time_t tbuf;
        struct tm *lt;
        rtems_time_of_day rt;
        rtems_interval ticks_per_second;

        if ( state )
                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 0;
}

static int
getServerTimespec(struct ntpPacketSmall *p, int state, void *usr_data)
{
struct timespec *ts = usr_data;
unsigned long long tmp;

        if ( 0 == state ) {
                ts->tv_sec  = ntohl( p->transmit_timestamp.integer );
                ts->tv_sec -= rtems_bsdnet_timeoffset + UNIX_BASE_TO_NTP_BASE;

                tmp  = 1000000000 * (unsigned long long)ntohl(p->transmit_timestamp.fraction);

                ts->tv_nsec = (unsigned long) (tmp>>32);
        }
        return 0;
}

int rtems_bsdnet_ntp_retry_count  = 5;
int rtems_bsdnet_ntp_timeout_secs = 5;
int rtems_bsdnet_ntp_bcast_timeout_secs = 80;

static int
tryServer (int i, int s, rtems_bsdnet_ntp_callback_t callback, void *usr_data)
{
        int l = 0;
        struct timeval tv;
        int farlen;
        struct sockaddr_in farAddr;
        struct ntpPacketSmall packet;

        if (i < 0)
                tv.tv_sec = rtems_bsdnet_ntp_bcast_timeout_secs;
        else
                tv.tv_sec = rtems_bsdnet_ntp_timeout_secs;
        tv.tv_usec = 0;
        if (setsockopt (s, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv, sizeof tv) < 0) {
                fprintf (stderr, "rtems_bsdnet_get_ntp() Can't set socket receive timeout: %s\n", strerror (errno));
                close (s);
                return -1;
        }
        if (i >= 0) {
                memset (&farAddr, 0, sizeof farAddr);
                farAddr.sin_family = AF_INET;
                farAddr.sin_port = htons (123);
                farAddr.sin_addr = rtems_bsdnet_ntpserver[i];
                memset (&packet, 0, sizeof packet);
                packet.li_vn_mode = (3 << 3) | 3; /* NTP version 3, client */
                if ( callback( &packet, 1, usr_data ) )
                        return -1;
                l = sendto (s, &packet, sizeof packet, 0, (struct sockaddr *)&farAddr, sizeof farAddr);
                if (l != sizeof packet) {
                        fprintf (stderr, "rtems_bsdnet_get_ntp() Can't send: %s\n", strerror (errno));
                        return -1;
                }
        } else {
                if ( callback( &packet, -1, usr_data ) )
                        return -1;
        }
        farlen = sizeof farAddr;
        i = recvfrom (s, &packet, sizeof packet, 0, (struct sockaddr *)&farAddr, &farlen);
        if (i == 0)
                fprintf (stderr, "rtems_bsdnet_get_ntp() Unexpected EOF");
        if (i < 0) {
                if ((errno == EWOULDBLOCK) || (errno == EAGAIN))
                        return -1;
                fprintf (stderr, "rtems_bsdnet_get_ntp() Can't receive: %s\n", strerror (errno));
        }

        if ( i >= sizeof packet &&
                ((packet.li_vn_mode & (0x7 << 3)) == (3 << 3)) &&
            ((packet.transmit_timestamp.integer != 0) || (packet.transmit_timestamp.fraction != 0)) &&
                0 == callback( &packet, 0 , usr_data) )
                return 0;

        return -1;
}

int rtems_bsdnet_get_ntp(int sock, rtems_bsdnet_ntp_callback_t callback, void *usr_data)
{
int s = -1;
int i;
int retry;
struct sockaddr_in myAddr;
int reuseFlag;
int ret;

        if ( !callback )
                callback = getServerTimespec;

        if ( sock < 0 ) {
        s = socket (AF_INET, SOCK_DGRAM, 0);
        if (s < 0) {
                fprintf (stderr, "rtems_bsdnet_get_ntp() Can't create socket: %s\n", strerror (errno));
                return -1;
        }
        reuseFlag = 1;
        if (setsockopt (s, SOL_SOCKET, SO_REUSEADDR, (char *)&reuseFlag, sizeof reuseFlag) < 0) {
                fprintf (stderr, "rtems_bsdnet_get_ntp() Can't set socket reuse: %s\n", strerror (errno));
                close (s);
                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) {
                fprintf (stderr, "rtems_bsdnet_get_ntp() Can't bind socket: %s\n", strerror (errno));
                close (s);
                return -1;
        }
        sock = s;
        }
        ret = -1;
        for (retry = 0 ; (ret == -1) && (retry < rtems_bsdnet_ntp_retry_count) ; retry++) {
                /*
                 * 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) {
                        ret = tryServer (-1, sock, callback, usr_data);
                }
                else {
                        for (i = 0 ; (ret == -1) && (i < rtems_bsdnet_ntpserver_count) ; i++) {
                                ret = tryServer (i, sock, callback, usr_data);
                        }
                }
        }
        if ( s >= 0 )
                close (s);
        return ret;
}

int
rtems_bsdnet_synchronize_ntp (int interval, rtems_task_priority priority)
{
        if (interval != 0) {
                fprintf (stderr, "Daemon-mode note yet supported.\n");
                errno = EINVAL;
                return -1;
        }
        return rtems_bsdnet_get_ntp( -1, processPacket, 0);
}