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- /* vi: set sw=4 ts=4: */
- /*
- * The Rdate command will ask a time server for the RFC 868 time
- * and optionally set the system time.
- *
- * by Sterling Huxley <sterling@europa.com>
- *
- * Licensed under GPLv2 or later, see file LICENSE in this source tree.
- */
- //config:config RDATE
- //config: bool "rdate (5.6 kb)"
- //config: default y
- //config: help
- //config: The rdate utility allows you to synchronize the date and time of your
- //config: system clock with the date and time of a remote networked system using
- //config: the RFC868 protocol, which is built into the inetd daemon on most
- //config: systems.
- //applet:IF_RDATE(APPLET(rdate, BB_DIR_USR_SBIN, BB_SUID_DROP))
- //kbuild:lib-$(CONFIG_RDATE) += rdate.o
- //usage:#define rdate_trivial_usage
- //usage: "[-s/-p] HOST"
- //usage:#define rdate_full_usage "\n\n"
- //usage: "Set and print time from HOST using RFC 868\n"
- //usage: "\n -s Only set system time"
- //usage: "\n -p Only print time"
- #include "libbb.h"
- enum { RFC_868_BIAS = 2208988800UL };
- static void socket_timeout(int sig UNUSED_PARAM)
- {
- bb_simple_error_msg_and_die("timeout connecting to time server");
- }
- static time_t askremotedate(const char *host)
- {
- uint32_t nett;
- int fd;
- /* Timeout for dead or inaccessible servers */
- alarm(10);
- signal(SIGALRM, socket_timeout);
- fd = create_and_connect_stream_or_die(host, bb_lookup_std_port("time", "tcp", 37));
- if (safe_read(fd, &nett, 4) != 4) /* read time from server */
- bb_error_msg_and_die("%s: %s", host, "short read");
- if (ENABLE_FEATURE_CLEAN_UP)
- close(fd);
- /* Convert from network byte order to local byte order.
- * RFC 868 time is seconds since 1900-01-01 00:00 GMT.
- * RFC 868 time 2,208,988,800 corresponds to 1970-01-01 00:00 GMT.
- * Subtract the RFC 868 time to get Linux epoch.
- */
- nett = ntohl(nett) - RFC_868_BIAS;
- if (sizeof(time_t) > 4) {
- /* Now we have 32-bit lsb of a wider time_t
- * Imagine that nett = 0x00000001,
- * current time cur = 0x123ffffffff.
- * Assuming our time is not some 40 years off,
- * remote time must be 0x12400000001.
- * Need to adjust our time by (int32_t)(nett - cur).
- */
- time_t cur = time(NULL);
- int32_t adjust = (int32_t)(nett - (uint32_t)cur);
- return cur + adjust;
- }
- /* This is not going to work, but what can we do */
- return (time_t)nett;
- }
- int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
- int rdate_main(int argc UNUSED_PARAM, char **argv)
- {
- time_t remote_time;
- unsigned flags;
- flags = getopt32(argv, "^" "sp" "\0" "-1");
- remote_time = askremotedate(argv[optind]);
- /* Manpages of various Unixes are confusing. What happens is:
- * (no opts) set and print time
- * -s: set time ("do not print the time")
- * -p: print time ("do not set, just print the remote time")
- * -sp: print time (that's what we do, not sure this is right)
- */
- if (!(flags & 2)) { /* no -p (-s may be present) */
- if (time(NULL) == remote_time)
- bb_simple_error_msg("current time matches remote time");
- else {
- struct timeval ts;
- ts.tv_sec = remote_time;
- ts.tv_usec = 0;
- xsettimeofday(&ts);
- }
- }
- if (flags != 1) /* not lone -s */
- printf("%s", ctime(&remote_time));
- return EXIT_SUCCESS;
- }
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