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   rtime    ( 3 )

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Имя (Name)

rtime - get time from a remote machine

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Синопсис (Synopsis)

#include <rpc/auth_des.h>

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

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Описание (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. Otherwise, the tcp/time socket (port 37) is used.

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Возвращаемое значение (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 to indicate the error.

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Ошибки (Error)

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.

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Атрибуты (Attributes)

For an explanation of the terms used in this section, see attributes(7).

┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface │ Attribute │ Value │ ├──────────────────────────────────────┼───────────────┼─────────┤ │rtime() │ Thread safety │ MT-Safe │ └──────────────────────────────────────┴───────────────┴─────────┘

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Примечание (Note)

Only IPv4 is supported.

Some in.timed versions support only TCP. Try the example program with use_tcp set to 1.

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Ошибки (баги) (Bugs)

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

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Примеры (Examples)

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);
       }

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Смотри также (See also)

ntpdate(1), inetd(8)

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