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 2021-03-22 "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
41 is set to indicate the error.
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
66 Interface Attribute Value
69 T} Thread safety MT-Safe
75 Only IPv4 is supported.
79 versions support only TCP.
80 Try the example program with
84 .\" Libc5 uses the prototype
87 .\" int rtime(struct sockaddr_in *, struct timeval *, struct timeval *);
93 .\" .IR <rpc/auth_des.h> .
96 in glibc 2.2.5 and earlier does not work properly on 64-bit machines.
98 This example requires that port 37 is up and open.
100 that the time entry within
102 is not commented out.
104 The program connects to a computer called "linux".
105 Using "localhost" does not work.
106 The result is the localtime of the computer "linux".
114 #include <rpc/auth_des.h>
117 static int use_tcp = 0;
118 static char *servername = "linux";
123 struct sockaddr_in name;
124 struct rpc_timeval time1 = {0,0};
125 struct rpc_timeval timeout = {1,0};
126 struct hostent *hent;
129 memset(&name, 0, sizeof(name));
131 hent = gethostbyname(servername);
132 memcpy(&name.sin_addr, hent\->h_addr, hent\->h_length);
134 ret = rtime(&name, &time1, use_tcp ? NULL : &timeout);
136 perror("rtime error");
138 time_t t = time1.tv_sec;
139 printf("%s\en", ctime(&t));