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htpdate.c
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/*
htpdate v1.3.7
Eddy Vervest <eddy@vervest.org>
http://www.vervest.org/htp
Synchronize local system with time offered by remote web servers
This program works with the timestamps return by web servers,
formatted as specified by HTTP/1.1 (RFC 2616, RFC 1123).
Example usage:
Debug mode (shows raw timestamps, round trip time (RTT) and
time difference):
htpdate -d www.example.com
Adjust time smoothly:
htpdate -a www.example.com
...see man page for more details
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
http://www.gnu.org/copyleft/gpl.html
*/
/* Needed to avoid implicit warnings from strptime */
#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>
#include <time.h>
#include <sys/time.h>
#include <sys/timex.h>
#include <syslog.h>
#include <stdarg.h>
#include <limits.h>
#include <pwd.h>
#include <grp.h>
#include <float.h>
#if defined __NetBSD__ || defined __FreeBSD__ || defined __APPLE__
#define adjtimex ntp_adjtime
#endif
#ifdef ENABLE_HTTPS
#include <openssl/ssl.h>
#endif
#define VERSION "1.3.7"
#define MAX_HTTP_HOSTS 16 /* 16 web servers */
#define DEFAULT_HTTP_PORT "80"
#define DEFAULT_PROXY_PORT "8080"
#define DEFAULT_IP_VERSION PF_UNSPEC /* IPv6 and IPv4 */
#define DEFAULT_HTTP_VERSION "1" /* HTTP/1.1 */
#define DEFAULT_TIME_LIMIT 31536000 /* 1 year */
#define NO_TIME_LIMIT -1
#define ERR_TIMESTAMP DBL_MAX /* Err fetching date in getHTTPdate */
#define DEFAULT_PRECISION 4 /* 4 request per host */
#define DEFAULT_MIN_SLEEP 1800 /* 30 minutes */
#define DEFAULT_MAX_SLEEP 115200 /* 32 hours */
#define MAX_DRIFT 32768000 /* 500 PPM */
#define DEFAULT_PID_FILE "/var/run/htpdate.pid"
#define HEADREQUESTSIZE 1024
#define URLSIZE 128
#define BUFFERSIZE 8192
#define PRINTBUFFERSIZE BUFFERSIZE
#define sign(x) (x < 0 ? (-1) : 1)
/* By default turn off "debug" and "log" mode */
static int debug = 0;
static int logmode = 0;
static int verifycert = 0;
/* Insertion sort is more efficient (and smaller) than qsort for small lists */
static void insertsort(double a[], int length) {
long i, j;
for (i = 1; i < length; i++) {
double value = a[i];
for (j = i - 1; j >= 0 && a[j] > value; j--)
a[j+1] = a[j];
a[j+1] = value;
}
}
/* Printlog is a slighty modified version from the one used in rdate */
static void printlog(int is_error, char *format, ...) {
va_list args;
char buf[PRINTBUFFERSIZE];
va_start(args, format);
(void) vsnprintf(buf, sizeof(buf), format, args);
va_end(args);
if (logmode)
syslog(is_error?LOG_WARNING:LOG_INFO, "%s", buf);
else
fprintf(is_error?stderr:stdout, "%s\n", buf);
}
/* Split argument in hostname/IP-address and TCP port
Supports IPv6 literal addresses, RFC 2732.
*/
static void splitURL(char **scheme, char **host, char **port, char **path) {
char *rb, *rc, *lb, *lc, *ps;
*path = "";
*scheme = NULL;
if ((ps = strcasestr(*host, "https://")) != NULL) {
#ifndef ENABLE_HTTPS
printlog(1, "HTTPS not supported, %s", *host);
return;
#endif
*scheme = "https://";
*port = "443";
*host = ps + 8;
}
if ((ps = strcasestr(*host, "http://")) != NULL) {
*host = ps + 7;
}
lb = strchr(*host, '[');
rb = strrchr(*host, ']');
lc = strchr(*host, ':');
rc = strrchr(*host, ':');
ps = strchr(*host, '/');
/* Extract URL path */
if (ps != NULL) {
ps[0] = '\0';
*path = ps + 1;
}
/* A (literal) IPv6 address with portnumber */
if (rb < rc && lb != NULL && rb != NULL) {
rb[0] = '\0';
*port = rc + 1;
*host = lb + 1;
return;
}
/* A (literal) IPv6 address without portnumber */
if (rb != NULL && lb != NULL) {
rb[0] = '\0';
*host = lb + 1;
return;
}
/* A IPv4 address or hostname with portnumber */
if (rc != NULL && lc == rc) {
rc[0] = '\0';
*port = rc + 1;
return;
}
}
static void swuid(int id) {
if (seteuid(id)) {
printlog(1, "seteuid() %i", id);
exit(1);
}
}
static void swgid(int id) {
if (setegid(id)) {
printlog(1, "setegid() %i", id);
exit(1);
}
}
static long long getoffset(char remote_time[25]) {
struct timeval timevalue = {0, 0};
struct timespec now;
struct tm tm;
clock_gettime(CLOCK_REALTIME, &now);
memset(&tm, 0, sizeof(struct tm));
if (strptime(remote_time, "%d %b %Y %T", &tm) != NULL) {
timevalue.tv_sec = timegm(&tm);
} else {
printlog(1, "unknown time format");
}
return now.tv_sec - timevalue.tv_sec;
}
static int sendHEAD(int server_s, char *headrequest, char *buffer) {
int ret = send(server_s, headrequest, strlen(headrequest), 0);
if (ret < 0) {
printlog(1, "Error sending");
return -1;
}
/* Receive data from the web server
The return code from recv() is the number of bytes received
*/
ret = recv(server_s, buffer, BUFFERSIZE - 1, 0) > 0;
return ret;
}
#ifdef ENABLE_HTTPS
static int sendHEADTLS(SSL *conn, char *headrequest, char *buffer) {
int ret = SSL_write(conn, headrequest, strlen(headrequest));
if (ret < 0) {
printlog(1, "Error sending: %i", ret);
return -1;
}
/* Receive data from the web server
The return code is the number of bytes received
*/
int socket_fd = SSL_get_fd(conn);
fcntl(socket_fd, F_SETFL, O_NONBLOCK);
int bytes_read, total_bytes = 0;
explicit_bzero(buffer, BUFFERSIZE -1);
while(1) {
bytes_read = SSL_read(conn, buffer + total_bytes, BUFFERSIZE - total_bytes);
// without sleep it doesn't always work
sleep(0.1);
if (bytes_read <= 0 && total_bytes > 0) {
break;
}
total_bytes += bytes_read;
if (total_bytes == BUFFERSIZE) {
// buffer is full, stop reading
break;
}
}
return ret;
}
static int proxyCONNECT(
int server_s,
char *host, char *port,
char *proxy, char *proxyport,
char *httpversion) {
char buffer[BUFFERSIZE] = {'\0'};
char connectrequest[URLSIZE] = {'\0'};
snprintf(connectrequest, URLSIZE,
"CONNECT %s:%s HTTP/1.%s\r\n\r\n", host, port, httpversion);
send(server_s, connectrequest, strlen(connectrequest), 0);
int ret = recv(server_s, buffer, BUFFERSIZE - 1, 0) > 0;
if (strstr(buffer, " 200 ") == NULL) {
printlog(1, "Proxy error: %s:%s\r\n%s", proxy, proxyport, buffer);
}
return ret;
}
#endif
static double getHTTPdate(
char *scheme,
char *host, char *port, char *path,
char *proxy, char *proxyport,
char *httpversion, int ipversion, int precision) {
int server_s;
int rc;
int polls = 0;
struct addrinfo hints, *res;
struct timespec sleepspec, now;
char headrequest[HEADREQUESTSIZE] = {'\0'};
char buffer[BUFFERSIZE] = {'\0'};
char url[URLSIZE] = {'\0'};
char *pdate = NULL;
/* Connect to web server via proxy server or directly */
memset(&hints, 0, sizeof(hints));
switch(ipversion) {
case 4: /* IPv4 only */
hints.ai_family = AF_INET;
break;
case 6: /* IPv6 only */
hints.ai_family = AF_INET6;
break;
default: /* Support IPv6 and IPv4 name resolution */
hints.ai_family = PF_UNSPEC;
}
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_CANONNAME;
if (proxy == NULL) {
rc = getaddrinfo(host, port, &hints, &res);
} else {
snprintf(url, URLSIZE, "http://%s:%s", host, port);
rc = getaddrinfo(proxy, proxyport, &hints, &res);
}
/* Was the hostname and service resolvable? */
if (rc) {
printlog(1, "%s host or service unavailable", host);
return(ERR_TIMESTAMP);
}
/* Build a combined HTTP/1.0 and 1.1 HEAD request
Pragma: no-cache, "forces" an HTTP/1.0 and 1.1 compliant
web server to return a fresh timestamp
*/
snprintf(headrequest, HEADREQUESTSIZE,
"HEAD %s/%s HTTP/1.%s\r\n"
"Host: %s\r\n"
"User-Agent: htpdate/"VERSION"\r\n"
"Pragma: no-cache\r\n"
"Cache-Control: no-cache\r\n"
"Connection: keep-alive\r\n\r\n",
url, path, httpversion, host);
/* Loop through the available canonical names */
do {
server_s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (server_s < 0) {
continue;
}
rc = connect(server_s, res->ai_addr, res->ai_addrlen);
if (rc) {
close(server_s);
server_s = -1;
continue;
}
break;
} while ((res = res->ai_next));
freeaddrinfo(res);
if (rc) {
printlog(1, "%s connection failed", host);
return(ERR_TIMESTAMP);
}
#ifdef ENABLE_HTTPS
SSL_CTX *tls_ctx = SSL_CTX_new(TLS_method());
SSL_CTX_set_default_verify_paths(tls_ctx);
SSL_CTX_set_verify_depth(tls_ctx, 4);
if (verifycert) SSL_CTX_set_verify(tls_ctx, SSL_VERIFY_PEER, NULL);
SSL *conn = SSL_new(tls_ctx);
SSL_set_tlsext_host_name(conn, host);
if (scheme) {
if (proxy) {
rc = proxyCONNECT(server_s, host, port, proxy, proxyport, httpversion);
if (rc != 1) {
printlog(1, "Proxy error: %i", rc);
return(ERR_TIMESTAMP);
}
}
if (! SSL_set_fd(conn, server_s)) {
printlog(1, "TLS error1");
return(ERR_TIMESTAMP);
} else {
if (SSL_connect(conn) != 1) {
printlog(1, "TLS error2");
return(ERR_TIMESTAMP);
}
}
}
#endif
long long offset = 0, first_offset = 0, prev_offset = 0;
long nap = 1e9L;
long when = nap >> precision;
do {
if (debug > 1)
printlog(0, "bisect: %i, when: %09li", polls, when);
/* Initialize timer */
clock_gettime(CLOCK_REALTIME, &now);
/* Initialize RTT (start of measurement) */
long rtt = now.tv_sec;
/* Wait till we reach the desired time, "when" */
sleepspec.tv_sec = 0;
if (when >= now.tv_nsec) {
sleepspec.tv_nsec = when - now.tv_nsec;
} else {
sleepspec.tv_nsec = 1e9 + when - now.tv_nsec;
rtt++;
}
nanosleep(&sleepspec, NULL);
/* Send HEAD request */
#ifdef ENABLE_HTTPS
if (scheme)
rc = sendHEADTLS(conn, headrequest, buffer);
else
#endif
rc = sendHEAD(server_s, headrequest, buffer);
if (!rc) {
printlog(1, "error from %s:%s", host, port );
offset = LLONG_MAX;
break;
} else {
clock_gettime(CLOCK_REALTIME, &now);
/* rtt contains round trip time in nanoseconds */
rtt = (now.tv_sec - rtt) * 1e9 + now.tv_nsec - when;
/* Look for the line that contains [dD]ate: */
if ((pdate = strcasestr(buffer, "date: ")) != NULL && strlen(pdate) >= 35) {
if (debug > 2) printlog(0, "%s", buffer);
char remote_time[25] = {'\0'};
strncpy(remote_time, pdate + 11, 24);
polls++;
offset = getoffset(remote_time);
nap >>= 1;
if (polls > 1) {
if (offset != prev_offset) nap = -nap;
} else {
first_offset=offset;
}
prev_offset=offset;
/* Print host, raw timestamp, round trip time */
if (debug)
printlog(0, "%-25s %s, %s (%li ms) => %li", host, port,
remote_time, rtt / (long)1e6, offset);
} else {
printlog(1, "%s no timestamp", host);
offset = LLONG_MAX;
break;
}
} /* bytes received */
precision--;
when += nap;
} while (precision >= 1);
close(server_s);
#ifdef ENABLE_HTTPS
if (scheme) SSL_shutdown(conn);
SSL_CTX_free(tls_ctx);
SSL_free(conn);
#endif
/* Rounding */
if (debug) printlog(0, "when: %ld, nap: %ld", when, nap);
if (offset == LLONG_MAX) return(ERR_TIMESTAMP);
if (when + nap == 1e9 && offset == 0) return 0;
/* Return the time delta between web server time (timevalue)
and system time (now)
*/
if (first_offset < 0) {
return(-first_offset + (1e9L-when)/(double)1e9L);
} else {
return(-first_offset + 1 - when/(double)1e9L);
}
}
static int setstatus(int precision) {
struct timex txc = {0};
txc.modes = MOD_STATUS | (1000000 >> precision) | MOD_MAXERROR;
txc.status &= ~STA_UNSYNC;
printlog(0, "Set clock synchronized");
return(adjtimex(&txc));
}
static int setclock(double timedelta, int setmode) {
struct timespec now;
struct timeval timeofday;
char buffer[32] = {'\0'};
if (timedelta == 0) {
printlog(0, "No time correction needed");
return(0);
}
switch (setmode) {
case 0: /* No time adjustment, just print time */
printlog(0, "Offset %.3f seconds", timedelta);
return(0);
case 1: /* Adjust time smoothly */
timeofday.tv_sec = (long)timedelta;
timeofday.tv_usec = (long)((timedelta - timeofday.tv_sec) * 1e6);
printlog(0, "Adjusting %.3f seconds", timedelta);
/* Become root */
swuid(0);
return(adjtime(&timeofday, NULL));
case 2: /* Set time */
printlog(0, "Setting %.3f seconds", timedelta);
clock_gettime(CLOCK_REALTIME, &now);
timedelta += (now.tv_sec + now.tv_nsec * 1e-9);
now.tv_sec = (long)timedelta;
now.tv_nsec = (long)(timedelta - now.tv_sec) * 1e9;
strftime(buffer, sizeof(buffer), "%c", localtime(&now.tv_sec));
printlog(0, "Set time: %s", buffer);
/* Become root */
swuid(0);
return(clock_settime(CLOCK_REALTIME, &now));
case 3: /* Set frequency, but first an adjust */
return(setclock(timedelta, 1));
default:
return(-1);
}
}
static int init_frequency(char *driftfile) {
struct timex tmx;
FILE *fp;
fp = fopen(driftfile, "r");
if (fp != NULL) {
if (fscanf(fp, "%li", &tmx.freq)) {
printlog(0, "Reading frequency from file %li", tmx.freq);
fclose(fp);
} else {
printlog(1, "Error reading frequency from %s", driftfile);
fclose(fp);
return -1;
}
} else {
printlog(1, "Error reading frequency from %s", driftfile);
return -1;
}
if ((tmx.freq < -MAX_DRIFT) || (tmx.freq > MAX_DRIFT))
tmx.freq = sign(tmx.freq) * MAX_DRIFT;
printlog(0, "Set frequency: %li", tmx.freq);
tmx.modes = MOD_FREQUENCY;
/* Become root */
swuid(0);
return(adjtimex(&tmx));
}
static int htpdate_adjtimex(double drift, char *driftfile, float confidence) {
struct timex tmx;
long freq;
FILE *fp;
/* Read current clock frequency */
tmx.modes = 0;
adjtimex(&tmx);
/* Calculate new frequency */
freq = (long)(65536e6 * drift);
/* Weighted average of current and new frequency */
tmx.freq = tmx.freq + freq * confidence;
if ((tmx.freq < -MAX_DRIFT) || (tmx.freq > MAX_DRIFT))
tmx.freq = sign(tmx.freq) * MAX_DRIFT;
printlog(0, "Set frequency %li", tmx.freq);
tmx.modes = MOD_FREQUENCY;
if (driftfile) {
fp = fopen(driftfile, "w");
if (fp != NULL) {
printlog(0, "Update %s", driftfile);
fprintf(fp, "%li", tmx.freq);
fclose(fp);
} else {
printlog(1, "Error writing frequency to %s", driftfile);
}
}
/* Become root */
swuid(0);
return(adjtimex(&tmx));
}
static void showhelp() {
puts("htpdate version "VERSION"\n\
Usage: htpdate [-046acdhlnqstvxDF] [-f driftfile] [-i pidfile] [-m minpoll]\n\
[-M maxpoll] [-p precision] [-P <proxyserver>[:port]]\n\
[-u user[:group]] <URL> ...\n\n\
-0 HTTP/1.0 request\n\
-4 Force IPv4 name resolution only\n\
-6 Force IPv6 name resolution only\n\
-a adjust time smoothly\n\
-c verify server certificate\n\
-d debug mode\n\
-D daemon mode\n\
-f drift/frequency file\n\
-F run daemon in foreground\n\
-h help\n\
-i pidfile\n\
-l use syslog for output\n\
-m minimum poll interval\n\
-M maximum poll interval\n\
-n no proxy (ignore http_proxy environment variable)\n\
-p precision (1..9, default 4)\n\
-P proxy server\n\
-q query only, don't make time changes (default)\n\
-s set time\n\
-t turn off sanity time check\n\
-u run daemon as user\n\
-v version\n\
-x adjust system clock frequency\n\
URL one of more URLs (max. 16), e.g. www.example.com\n");
return;
}
/* Run htpdate in daemon mode */
static void runasdaemon(char *pidfile) {
FILE *pid_file;
pid_t pid;
/* Check if htpdate is already running (pid exists)*/
pid_file = fopen(pidfile, "r");
if (pid_file) {
fputs("htpdate already running\n", stderr);
exit(1);
}
pid = fork();
if (pid < 0) {
fputs("fork()\n", stderr);
exit(1);
}
if (pid > 0) exit(0);
/* Create a new SID for the child process */
if (setsid () < 0) exit(1);
/* Close out the standard file descriptors */
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
signal(SIGHUP, SIG_IGN);
/* Change the file mode mask */
umask(0);
/* Change the current working directory */
if (chdir("/") < 0) {
printlog(1, "chdir()");
exit(1);
}
/* Second fork, to become the grandchild */
pid = fork();
if (pid < 0) {
printlog(1, "fork()");
exit(1);
}
if (pid > 0) {
/* Write a pid file */
pid_file = fopen(pidfile, "w");
if (!pid_file) {
printlog(1, "Error writing pid file");
exit(1);
} else {
fprintf(pid_file, "%d\n", pid);
fclose(pid_file);
}
exit(0);
}
}
int main(int argc, char *argv[]) {
char *host = NULL, *proxy = NULL, *proxyport = NULL;
char *port = NULL;
char *path = NULL;
char *scheme = NULL;
char *httpversion = DEFAULT_HTTP_VERSION;
char *pidfile = DEFAULT_PID_FILE;
char *user = NULL, *userstr = NULL, *group = NULL;
double timeavg, drift = 0;
double timedelta[MAX_HTTP_HOSTS-1];
int numservers;
int precision = DEFAULT_PRECISION;
int setmode = 0;
int i, param;
int daemonize = 0, foreground = 0;
int noproxyenv = 0;
int ipversion = DEFAULT_IP_VERSION;
long long timelimit = DEFAULT_TIME_LIMIT;
int minsleep = DEFAULT_MIN_SLEEP;
int maxsleep = DEFAULT_MAX_SLEEP;
int sleeptime = minsleep;
int sw_uid = 0, sw_gid = 0;
time_t starttime = 0;
struct passwd *pw;
struct group *gr;
extern char *optarg;
extern int optind;
char *driftfile = NULL;
/* Parse the command line switches and arguments */
while ((param = getopt(argc, argv, "046acdf:hi:lm:np:qstu:vxDFM:P:")) != -1)
switch(param) {
case '0': /* HTTP/1.0 */
httpversion = "0";
break;
case '4': /* IPv4 only */
ipversion = 4;
break;
case '6': /* IPv6 only */
ipversion = 6;
break;
case 'a': /* adjust time */
setmode = 1;
break;
case 'c': /* server certificat verification */
verifycert = 1;
break;
case 'd': /* turn debug on */
if (debug <= 3) debug++;
break;
case 'f': /* drift file */
driftfile = (char *)optarg;
init_frequency(driftfile);
break;
case 'h': /* show help */
showhelp();
exit(0);
case 'i': /* pid file */
pidfile = (char *)optarg;
break;
case 'l': /* log mode */
logmode = 1;
break;
case 'm': /* minimum poll interval */
if ((minsleep = atoi(optarg)) <= 0) {
fputs("Invalid sleep time\n", stderr);
exit(1);
}
sleeptime = minsleep;
break;
case 'n': /* don't get proxy from environment */
noproxyenv = 1;
break;
case 'p': /* precision */
precision = atoi(optarg) ;
if ((precision < 1) || (precision > 9)) {
fputs("Invalid precision\n", stderr);
exit(1);
}
break;
case 'q': /* query only (default) */
break;
case 's': /* set time */
setmode = 2;
break;
case 't': /* disable "sanity" time check */
timelimit = NO_TIME_LIMIT;
break;
case 'u': /* drop root privileges and run as user */
user = (char *)optarg;
userstr = strchr(user, ':');
if (userstr != NULL) {
userstr[0] = '\0';
group = userstr + 1;
}
if ((pw = getpwnam(user)) != NULL) {
sw_uid = pw->pw_uid;
sw_gid = pw->pw_gid;
} else {
printf("Unknown user %s\n", user);
exit(1);
}
if (group != NULL) {
if ((gr = getgrnam(group)) != NULL) {
sw_gid = gr->gr_gid;
} else {
printf("Unknown group %s\n", group);
exit(1);
}
}
break;
case 'v': /* print version */
printf("htpdate version %s\n", VERSION);
exit(0);
case 'x': /* adjust time and clock frequency */
setmode = 3;
if (maxsleep > 14400) maxsleep = 14400;
if (precision < 7) precision = 7;
break;
case 'D': /* run as daemon */
daemonize = 1;
logmode = 1;
break;
case 'F': /* run daemon in foreground, don't fork */
foreground = 1;
break;
case 'M': /* maximum poll interval */
if ((maxsleep = atoi(optarg)) <= 0) {
fputs("Invalid sleep time\n", stderr);
exit(1);
}
break;
case 'P':
proxyport = DEFAULT_PROXY_PORT;
char *proxywithport = strdup((char *)optarg);
proxy = proxywithport;
splitURL(&scheme, &proxy, &proxyport, &path);
break;
case '?':
return 1;
default:
abort();
}
/* Display help page, if no servers are specified */
if (argv[optind] == NULL) {
showhelp();
exit(1);
}
/* Exit if too many servers are specified */
numservers = argc - optind;
if (numservers > MAX_HTTP_HOSTS) {
fputs("Too many servers\n", stderr);
exit(1);
}
/* Use http_proxy environment variable */
if (getenv("http_proxy") && !noproxyenv) {
if ((proxy = strstr(getenv("http_proxy"), "http://")) == NULL) {
printlog(1, "Invalid proxy specified: %s", getenv("http_proxy"));
exit(1);
}
if (debug) printlog(0, "Proxy: %s", proxy);
proxy += 7;
proxyport = DEFAULT_PROXY_PORT;
splitURL(&scheme, &proxy, &proxyport, &path);
}
/* One must be "root" to change the system time */
if ((getuid() != 0) && (setmode || daemonize || foreground)) {
fputs("Only root can change time\n", stderr);
exit(1);
}
/* Run as a daemonize when -D is set */
if (daemonize) {
runasdaemon(pidfile);
}
/* Query only mode doesn't exist in daemon or foreground mode */
if (daemonize || foreground) {
printlog(0, "htpdate version "VERSION" started");
if (!setmode) setmode = 1;
}
/* Now we are root, we drop the privileges (if specified) */
if (sw_gid) swgid(sw_gid);
if (sw_uid) swuid(sw_uid);
#ifdef ENABLE_HTTPS
SSL_library_init();
#endif
/* Infinite poll cycle loop in daemonize or foreground mode */
do {
/* Initialize number of received valid timestamps, good timestamps
and the average of the good timestamps
*/
int validtimes = 0, goodtimes = 0;
double sumtimes = 0, mean = 0;
/* Loop through the time sources (web servers); poll cycle */
for (i = optind; i < argc; i++) {
/* host:port is stored in argv[i] */
char *hostport = strdup(argv[i]);
host = hostport;
port = DEFAULT_HTTP_PORT;
splitURL(&scheme, &host, &port, &path);
double offset = getHTTPdate(scheme, host, port, path,
proxy, proxyport, httpversion, ipversion, precision);
free(hostport);
if (debug && offset != ERR_TIMESTAMP) {
printlog(0, "offset: %.6f", offset);
}
/* Only include valid responses in timedelta[] */
if ((timelimit == NO_TIME_LIMIT && offset != ERR_TIMESTAMP) || (offset < timelimit && offset > -timelimit)) {
timedelta[validtimes] = offset;
validtimes++;
}
}
/* Sort the timedelta results */
insertsort(timedelta, validtimes);
/* Mean time value */
mean = timedelta[validtimes/2];
/* Filter out the bogus timevalues. A timedelta which is more than
1 second off from mean, is considered a 'false ticker'.
NTP synced web servers can never be more off than a second.
*/
for (i = 0; i < validtimes; i++) {
if ((timedelta[i]-mean) < .5 && (timedelta[i]-mean) > -.5) {
sumtimes += timedelta[i];
goodtimes++;
}
}
/* Check if we have at least one valid response */
if (goodtimes) {
timeavg = sumtimes / goodtimes;
/* Avoid bouncing between upper/lower limit when (almost) in sync */
if (timeavg < 1 && timeavg > -1) timeavg /= 2;
if (debug > 1)
printlog(0, "#: %d, mean: %.3f, average: %.3f", goodtimes, mean, timeavg);
/* Do I really need to change the time? */
if (sumtimes || !(daemonize || foreground)) {
if (setclock(timeavg, setmode) < 0)
printlog(1, "Time change failed");
/* Drop root privileges again */
if (sw_uid) swuid(sw_uid);
if (daemonize || foreground) {
if (starttime) {
/* Calculate systematic clock drift */
drift = timeavg / (time(NULL) - starttime);
printlog(0, "Drift %.2f PPM, %.2f s/day", drift*1e6, drift*86400);
/* Adjust system clock */
if (setmode == 3) {
starttime = time(NULL);
/* Adjust the clock frequency */
if (htpdate_adjtimex(drift, driftfile, (float)sleeptime / (float)maxsleep) < 0)
printlog(1, "Frequency change failed");
/* Drop root privileges again */
if (sw_uid) swuid(sw_uid);
}
} else {
starttime = time(NULL);
}
/* Decrease polling interval to minimum */
sleeptime = minsleep;
/* Sleep for 30 minutes after a time adjust or set */
sleep(DEFAULT_MIN_SLEEP);
}