NAME

SNTP Client – sntpc

SYNOPSIS

#include <tcpinit.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h >
#include <sntp.h >

int sntp_gettime(const char *srv_addr, struct timespec *ts);

// For dual TCP stack:

int sntp_gettime(const char *srv_addr, struct timespec *ts, int ip_ver);

DESCRIPTION

The SNTP Client gets time from NTP server.

Parameters:

• srv_addr – pointer to the string with NTP server IPv4 address.
• ts – pointer to timespec structure in which will be stored gotten time. If ts == NULL, time will be directly set as system time.
• ip_ver – version of IP protocol (4 or 6).

Return values:

• 0 – time successfully got from NTP server.
• -1 – error, see errno for detail.

SPECIFIC OPTIONS (Compile time)

EXAMPLE

This partial example shows the get time to user structure and set it as system time:

	//get time to user structure
	sntp_gettime("192.168.16.227", &ts); 
	xprintf("Get sntp time: %lu.%.9lu\n", (unsigned long)ts.tv_sec, (unsigned long)ts.tv_nsec);

	//get time and set it as system time
	sntp_gettime("192.168.16.227", NULL); 
	clock_gettime(CLOCK_REALTIME, &ts);
	xprintf("Get system time: %lu.%.9lu\n", (unsigned long)ts.tv_sec, (unsigned long)ts.tv_nsec);

This partial example shows how to get time to user structure under dual TCP stack:

	xprintf("\nipv4 interface\n");
	//get time to user structure
	sntp_gettime("192.168.16.227", &ts, 4);
	xprintf("Get sntp time: %lu.%.9lu\n", (unsigned long)ts.tv_sec, (unsigned long)ts.tv_nsec);

	//get time and set it as system time
	sntp_gettime("192.168.16.227", NULL, 4);
	clock_gettime(CLOCK_REALTIME, &ts);
	xprintf("Get system time: %lu.%.9lu\n", (unsigned long)ts.tv_sec, (unsigned long)ts.tv_nsec);

#ifdef SNTPC_IP6_ENABLE
	xprintf("\nipv6 interface\n");
	//get time to user structure
	sntp_gettime("fe80::1e6f:65ff:fe8f:5295", &ts, 6);
	xprintf("Get sntp time: %lu.%.9lu\n", (unsigned long)ts.tv_sec, (unsigned long)ts.tv_nsec);

	//get time and set it as system time
	sntp_gettime("fe80::1e6f:65ff:fe8f:5295", NULL, 6);
	clock_gettime(CLOCK_REALTIME, &ts);
	xprintf("Get system time: %lu.%.9lu\n", (unsigned long)ts.tv_sec, (unsigned long)ts.tv_nsec);
#endif

NOTES

There is a demo available for the Unison and DSPnano sntp client which is found in installdir/demos.

SEE ALSO

tcpd