1 .\" Copyright 2003 walter harms (walter.harms@informatik.uni-oldenburg.de)
3 .\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
4 .\" Distributed under GPL
7 .\" Modified 2003-04-04 Walter Harms
8 .\" <walter.harms@informatik.uni-oldenburg.de>
10 .\" Slightly polished, aeb, 2003-04-06
12 .TH RTIME 3 2019-03-06 "GNU" "Linux Programmer's Manual"
14 rtime \- get time from a remote machine
17 .B "#include <rpc/auth_des.h>"
19 .BI "int rtime(struct sockaddr_in *" addrp ", struct rpc_timeval *" timep ,
20 .BI " struct rpc_timeval *" timeout );
23 This function uses the Time Server Protocol as described in
24 RFC\ 868 to obtain the time from a remote machine.
26 The Time Server Protocol gives the time in seconds since
27 00:00:00 UTC, 1 Jan 1900,
28 and this function subtracts the appropriate constant in order to
29 convert the result to seconds since the
30 Epoch, 1970-01-01 00:00:00 +0000 (UTC).
34 is non-NULL, the udp/time socket (port 37) is used.
35 Otherwise, the tcp/time socket (port 37) is used.
37 On success, 0 is returned, and the obtained 32-bit time value is stored in
39 In case of error \-1 is returned, and
43 All errors for underlying functions
53 The number of returned bytes is not 4.
56 The waiting time as defined in timeout has expired.
58 For an explanation of the terms used in this section, see
64 Interface Attribute Value
67 T} Thread safety MT-Safe
70 Only IPv4 is supported.
74 versions support only TCP.
75 Try the example program with
79 Libc5 uses the prototype
82 int rtime(struct sockaddr_in *, struct timeval *, struct timeval *);
88 .IR <rpc/auth_des.h> .
91 in glibc 2.2.5 and earlier does not work properly on 64-bit machines.
93 This example requires that port 37 is up and open.
95 that the time entry within
99 The program connects to a computer called "linux".
100 Using "localhost" does not work.
101 The result is the localtime of the computer "linux".
109 #include <rpc/auth_des.h>
112 static int use_tcp = 0;
113 static char *servername = "linux";
118 struct sockaddr_in name;
119 struct rpc_timeval time1 = {0,0};
120 struct rpc_timeval timeout = {1,0};
121 struct hostent *hent;
124 memset(&name, 0, sizeof(name));
126 hent = gethostbyname(servername);
127 memcpy(&name.sin_addr, hent\->h_addr, hent\->h_length);
129 ret = rtime(&name, &time1, use_tcp ? NULL : &timeout);
131 perror("rtime error");
133 time_t t = time1.tv_sec;
134 printf("%s\en", ctime(&t));