/*
* 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 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, sizeof myAddr, 0);
myAddr.sin_family = AF_INET;
myAddr.sin_port = htons (123);
myAddr.sin_addr.s_addr = htonl (INADDR_ANY);
printf ("Bind socket.\n");
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, sizeof farAddr, 0);
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, sizeof packet, 0);
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) {
printf ("%d\n", errno);
if (errno == EWOULDBLOCK)
continue;
rtems_panic ("Can't receive: %s", strerror (errno));
}
if (i >= sizeof packet) {
if (processPacket (&packet))
return 0;
}
}
}
