#include <rpc/des_crypt.h>
int rtime(struct sockaddr_in *addrp, struct rpc_timeval *timep,
struct rpc_timeval *timeout);
The Time Server Protocol gives the time in seconds since 00:00:00 UTC, 1 Jan 1900, and this function subtracts the appropriate constant in order to convert the result to seconds since 00:00:00 UTC, 1 Jan 1970, the Unix Epoch.
When timeout is non-NULL, the udp/time socket (port 37) is used. Otherwise, the tcp/time socket (port 37) is used.
Some in.timed versions only support TCP. Try the example program with use_tcp set to 1.
Libc5 uses the prototype
int rtime(struct sockaddr_in *, struct timeval *, struct timeval *);
and requires
<sys/time.h>
instead of
<rpc/auth_des.h>.
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <rpc/auth_des.h>
#include <netdb.h>
int use_tcp = 0;
char *servername = "linux";
int
main(void)
{
struct sockaddr_in name;
struct rpc_timeval time1 = {0,0};
struct rpc_timeval timeout = {1,0};
struct hostent *hent;
int ret;
memset((char *) &name, 0, sizeof(name));
sethostent(1);
hent = gethostbyname(servername);
memcpy((char *) &name.sin_addr, hent->h_addr, hent->h_length);
ret = rtime(&name, &time1, use_tcp ? NULL : &timeout);
if (ret < 0)
perror("rtime error");
else
printf("%s\n", ctime((time_t *) &time1.tv_sec));
exit(EXIT_SUCCESS);
}