| /* 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_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_error_msg("current time matches remote time"); |
| else |
| if (stime(&remote_time) < 0) |
| bb_perror_msg_and_die("can't set time of day"); |
| } |
| |
| if (flags != 1) /* not lone -s */ |
| printf("%s", ctime(&remote_time)); |
| |
| return EXIT_SUCCESS; |
| } |