RTIME(3)                   Linux Programmer's Manual                  RTIME(3)

NAME
       rtime - get time from a remote machine

SYNOPSIS
       #include <rpc/auth_des.h>

       int rtime(struct sockaddr_in *addrp, struct rpc_timeval *timep,
                 struct rpc_timeval *timeout);

DESCRIPTION
       This  function uses the Time Server Protocol as described in RFC 868 to
       obtain the time from a remote machine.

       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  the  Epoch,  1970-01-01
       00:00:00 +0000 (UTC).

       When  timeout is non-NULL, the udp/time socket (port 37) is used.  Oth-
       erwise, the tcp/time socket (port 37) is used.

RETURN VALUE
       On success, 0 is returned, and the obtained 32-bit time value is stored
       in  timep->tv_sec.   In  case of error -1 is returned, and errno is set
       appropriately.

ERRORS
       All errors for underlying functions (sendto(2),  poll(2),  recvfrom(2),
       connect(2), read(2)) can occur.  Moreover:

       EIO    The number of returned bytes is not 4.

       ETIMEDOUT
              The waiting time as defined in timeout has expired.

ATTRIBUTES
   Multithreading (see pthreads(7))
       The rtime() function is thread-safe.

NOTES
       Only IPv4 is supported.

       Some  in.timed versions support only 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>.

BUGS
       rtime() in glibc 2.2.5 and earlier does not  work  properly  on  64-bit
       machines.

EXAMPLE
       This  example requires that port 37 is up and open.  You may check that
       the time entry within /etc/inetd.conf is not commented out.

       The program connects to a computer called "linux".   Using  "localhost"
       does not work.  The result is the localtime of the computer "linux".

       #include <stdio.h>
       #include <stdlib.h>
       #include <errno.h>
       #include <string.h>
       #include <time.h>
       #include <rpc/auth_des.h>
       #include <netdb.h>

       static int use_tcp = 0;
       static 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(&name, 0, sizeof(name));
           sethostent(1);
           hent = gethostbyname(servername);
           memcpy(&name.sin_addr, hent->h_addr, hent->h_length);

           ret = rtime(&name, &time1, use_tcp ? NULL : &timeout);
           if (ret < 0)
               perror("rtime error");
           else {
               time_t t = time1.tv_sec;
               printf("%s\n", ctime(&t));
           }

           exit(EXIT_SUCCESS);
       }

SEE ALSO
       ntpdate(1), inetd(8)

COLOPHON
       This  page  is  part of release 3.74 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.

GNU                               2014-05-28                          RTIME(3)

Czas wygenerowania: 0.00050 sek.

Created with the man page lookup class by Andrew Collington.
Based on a C man page viewer by Vadim Pavlov
Unicode soft-hyphen fix (as used by RedHat) by Dan Edwards
Some optimisations by Eli Argon
Caching idea and code contribution by James Richardson

Copyright © 2003-2023 Linux.pl
Hosted by Hosting Linux.pl