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+/*****************************************************************************
+ * _ _ ____ _
+ * Project ___| | | | _ \| |
+ * / __| | | | |_) | |
+ * | (__| |_| | _ <| |___
+ * \___|\___/|_| \_\_____|
+ *
+ * $Id$
+ *
+ * This example code only builds as-is on Windows.
+ *
+ * Synchronising your computer clock via Internet time server usually relies
+ * on DAYTIME, TIME, or NTP protocols. These protocols provide good accurate
+ * time synchronisation but it does not work very well through a
+ * firewall/proxy. Some adjustment has to be made to the firewall/proxy for
+ * these protocols to work properly.
+ *
+ * There is an indirect method. Since most webserver provide server time in
+ * their HTTP header, therefore you could synchronise your computer clock
+ * using HTTP protocol which has no problem with firewall/proxy.
+ *
+ * For this software to work, you should take note of these items.
+ * 1. Your firewall/proxy must allow your computer to surf internet.
+ * 2. Webserver system time must in sync with the NTP time server,
+ * or at least provide an accurate time keeping.
+ * 3. Webserver HTTP header does not provide the milliseconds units,
+ * so there is no way to get very accurate time.
+ * 4. This software could only provide an accuracy of +- a few seconds,
+ * as Round-Trip delay time is not taken into consideration.
+ * Compensation of network, firewall/proxy delay cannot be simply divide
+ * the Round-Trip delay time by half.
+ * 5. Win32 SetSystemTime() API will set your computer clock according to
+ * GMT/UTC time. Therefore your computer timezone must be properly set.
+ * 6. Webserver data should not be cached by the proxy server. Some
+ * webserver provide Cache-Control to prevent caching.
+ *
+ * References:
+ * http://tf.nist.gov/timefreq/service/its.htm
+ * http://tf.nist.gov/timefreq/service/firewall.htm
+ *
+ * Usage:
+ * This software will synchronise your computer clock only when you issue
+ * it with --synctime. By default, it only display the webserver's clock.
+ *
+ * Written by: Frank (contributed to libcurl)
+ *
+ * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
+ * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * IN NO EVENT SHALL THE AUTHOR OF THIS SOFTWARE BE LIABLE FOR
+ * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
+ * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+ * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
+ * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ *
+ */
+
+#include <stdio.h>
+#include <time.h>
+#include <windows.h>
+#include <curl/curl.h>
+
+
+#define MAX_STRING 256
+#define MAX_STRING1 MAX_STRING+1
+
+typedef struct
+{
+ char http_proxy[MAX_STRING1];
+ char proxy_user[MAX_STRING1];
+ char timeserver[MAX_STRING1];
+} conf_t;
+
+char DefaultTimeServer[4][MAX_STRING1] =
+{
+ "http://nist.time.gov/timezone.cgi?UTC/s/0",
+ "http://www.google.com/",
+ "http://www.worldtimeserver.com/current_time_in_UTC.aspx",
+ "http://www.worldtime.com/cgi-bin/wt.cgi"
+};
+
+char *DayStr[] = {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
+char *MthStr[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+
+int ShowAllHeader;
+int AutoSyncTime;
+SYSTEMTIME SYSTime;
+SYSTEMTIME LOCALTime;
+
+#define HTTP_COMMAND_HEAD 0
+#define HTTP_COMMAND_GET 1
+
+
+size_t SyncTime_CURL_WriteOutput(void *ptr, size_t size, size_t nmemb,
+ void *stream)
+{
+ fwrite(ptr, size, nmemb, stream);
+ return(nmemb*size);
+}
+
+size_t SyncTime_CURL_WriteHeader(void *ptr, size_t size, size_t nmemb,
+ void *stream)
+{
+ int i, RetVal;
+ char TmpStr1[26], TmpStr2[26];
+
+ if (ShowAllHeader == 1)
+ fprintf(stderr, "%s", (char *)(ptr));
+
+ if (strncmp((char *)(ptr), "Date:", 5) == 0) {
+ if (ShowAllHeader == 0)
+ fprintf(stderr, "HTTP Server. %s", (char *)(ptr));
+
+ if (AutoSyncTime == 1) {
+ *TmpStr1 = 0;
+ *TmpStr2 = 0;
+ if (strlen((char *)(ptr)) > 50) /* Can prevent buffer overflow to
+ TmpStr1 & 2? */
+ AutoSyncTime = 0;
+ else {
+ RetVal = sscanf ((char *)(ptr), "Date: %s %d %s %d %d:%d:%d",
+ TmpStr1, &SYSTime.wDay, TmpStr2, &SYSTime.wYear,
+ &SYSTime.wHour, &SYSTime.wMinute, &SYSTime.wSecond);
+
+ if (RetVal == 7) {
+
+ SYSTime.wMilliseconds = 500; /* adjust to midpoint, 0.5 sec */
+ for (i=0; i<12; i++) {
+ if (strcmp(MthStr[i], TmpStr2) == 0) {
+ SYSTime.wMonth = i+1;
+ break;
+ }
+ }
+ AutoSyncTime = 3; /* Computer clock will be adjusted */
+ }
+ else {
+ AutoSyncTime = 0; /* Error in sscanf() fields conversion */
+ }
+ }
+ }
+ }
+
+ if (strncmp((char *)(ptr), "X-Cache: HIT", 12) == 0) {
+ fprintf(stderr, "ERROR: HTTP Server data is cached."
+ " Server Date is no longer valid.\n");
+ AutoSyncTime = 0;
+ }
+ return(nmemb*size);
+}
+
+void SyncTime_CURL_Init(CURL *curl, char *proxy_port,
+ char *proxy_user_password)
+{
+ if (strlen(proxy_port) > 0)
+ curl_easy_setopt(curl, CURLOPT_PROXY, proxy_port);
+
+ if (strlen(proxy_user_password) > 0)
+ curl_easy_setopt(curl, CURLOPT_PROXYUSERPWD, proxy_user_password);
+
+ /* Trick Webserver by claiming that you are using Microsoft WinXP SP2, IE6 */
+ curl_easy_setopt(curl, CURLOPT_USERAGENT,
+ "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
+ curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, *SyncTime_CURL_WriteOutput);
+ curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, *SyncTime_CURL_WriteHeader);
+}
+
+int SyncTime_CURL_Fetch(CURL *curl, char *URL_Str, char *OutFileName,
+ int HttpGetBody)
+{
+ FILE *outfile;
+ CURLcode res;
+
+ outfile = NULL;
+ if (HttpGetBody == HTTP_COMMAND_HEAD)
+ curl_easy_setopt(curl, CURLOPT_NOBODY, 1);
+ else {
+ outfile = fopen(OutFileName, "wb");
+ curl_easy_setopt(curl, CURLOPT_WRITEDATA, outfile);
+ }
+
+ curl_easy_setopt(curl, CURLOPT_URL, URL_Str);
+ res = curl_easy_perform(curl);
+ if (outfile != NULL)
+ fclose(outfile);
+ return res; /* (CURLE_OK) */
+}
+
+void showUsage(void)
+{
+ fprintf(stderr, "SYNCTIME: Synchronising computer clock with time server"
+ " using HTTP protocol.\n");
+ fprintf(stderr, "Usage : SYNCTIME [Option]\n");
+ fprintf(stderr, "Options :\n");
+ fprintf(stderr, " --server=WEBSERVER Use this time server instead"
+ " of default.\n");
+ fprintf(stderr, " --showall Show all HTTP header.\n");
+ fprintf(stderr, " --synctime Synchronising computer clock"
+ " with time server.\n");
+ fprintf(stderr, " --proxy-user=USER[:PASS] Set proxy username and"
+ " password.\n");
+ fprintf(stderr, " --proxy=HOST[:PORT] Use HTTP proxy on given"
+ " port.\n");
+ fprintf(stderr, " --help Print this help.\n");
+ fprintf(stderr, "\n");
+ return;
+}
+
+int conf_init(conf_t *conf)
+{
+ int i;
+
+ *conf->http_proxy = 0;
+ for (i=0; i<MAX_STRING1; i++)
+ conf->proxy_user[i] = 0; /* Clean up password from memory */
+ *conf->timeserver = 0;
+ return 1;
+}
+
+int main(int argc, char *argv[])
+{
+ CURL *curl;
+ conf_t conf[1];
+ int OptionIndex;
+ struct tm *lt;
+ struct tm *gmt;
+ time_t tt;
+ time_t tt_local;
+ time_t tt_gmt;
+ double tzonediffFloat;
+ int tzonediffWord;
+ char timeBuf[61];
+ char tzoneBuf[16];
+ int RetValue;
+
+ OptionIndex = 0;
+ ShowAllHeader = 0; /* Do not show HTTP Header */
+ AutoSyncTime = 0; /* Do not synchronise computer clock */
+ RetValue = 0; /* Successful Exit */
+ conf_init(conf);
+
+ if (argc > 1) {
+ while (OptionIndex < argc) {
+ if (strncmp(argv[OptionIndex], "--server=", 9) == 0)
+ snprintf(conf->timeserver, MAX_STRING, "%s", &argv[OptionIndex][9]);
+
+ if (strcmp(argv[OptionIndex], "--showall") == 0)
+ ShowAllHeader = 1;
+
+ if (strcmp(argv[OptionIndex], "--synctime") == 0)
+ AutoSyncTime = 1;
+
+ if (strncmp(argv[OptionIndex], "--proxy-user=", 13) == 0)
+ snprintf(conf->proxy_user, MAX_STRING, "%s", &argv[OptionIndex][13]);
+
+ if (strncmp(argv[OptionIndex], "--proxy=", 8) == 0)
+ snprintf(conf->http_proxy, MAX_STRING, "%s", &argv[OptionIndex][8]);
+
+ if ((strcmp(argv[OptionIndex], "--help") == 0) ||
+ (strcmp(argv[OptionIndex], "/?") == 0)) {
+ showUsage();
+ return 0;
+ }
+ OptionIndex++;
+ }
+ }
+
+ if (*conf->timeserver == 0) /* Use default server for time information */
+ snprintf(conf->timeserver, MAX_STRING, "%s", DefaultTimeServer[0]);
+
+ /* Init CURL before usage */
+ curl_global_init(CURL_GLOBAL_ALL);
+ curl = curl_easy_init();
+ if (curl) {
+ SyncTime_CURL_Init(curl, conf->http_proxy, conf->proxy_user);
+
+ /* Calculating time diff between GMT and localtime */
+ tt = time(0);
+ lt = localtime(&tt);
+ tt_local = mktime(lt);
+ gmt = gmtime(&tt);
+ tt_gmt = mktime(gmt);
+ tzonediffFloat = difftime(tt_local, tt_gmt);
+ tzonediffWord = (int)(tzonediffFloat/3600.0);
+
+ if ((double)(tzonediffWord * 3600) == tzonediffFloat)
+ snprintf(tzoneBuf, 15, "%+03d'00'", tzonediffWord);
+ else
+ snprintf(tzoneBuf, 15, "%+03d'30'", tzonediffWord);
+
+ /* Get current system time and local time */
+ GetSystemTime(&SYSTime);
+ GetLocalTime(&LOCALTime);
+ snprintf(timeBuf, 60, "%s, %02d %s %04d %02d:%02d:%02d.%03d, ",
+ DayStr[LOCALTime.wDayOfWeek], LOCALTime.wDay,
+ MthStr[LOCALTime.wMonth-1], LOCALTime.wYear,
+ LOCALTime.wHour, LOCALTime.wMinute, LOCALTime.wSecond,
+ LOCALTime.wMilliseconds);
+ fprintf(stderr, "\nBefore HTTP. Date: %s%s\n\n", timeBuf, tzoneBuf);
+
+ /* HTTP HEAD command to the Webserver */
+ fprintf(stderr, "Fetch: %s\n", conf->timeserver);
+ SyncTime_CURL_Fetch(curl, conf->timeserver, "index.htm",
+ HTTP_COMMAND_HEAD);
+
+ GetLocalTime(&LOCALTime);
+ snprintf(timeBuf, 60, "%s, %02d %s %04d %02d:%02d:%02d.%03d, ",
+ DayStr[LOCALTime.wDayOfWeek], LOCALTime.wDay,
+ MthStr[LOCALTime.wMonth-1], LOCALTime.wYear,
+ LOCALTime.wHour, LOCALTime.wMinute, LOCALTime.wSecond,
+ LOCALTime.wMilliseconds);
+ fprintf(stderr, "\nAfter HTTP. Date: %s%s\n", timeBuf, tzoneBuf);
+
+ if (AutoSyncTime == 3) {
+ /* Synchronising computer clock */
+ if (!SetSystemTime(&SYSTime)) { /* Set system time */
+ fprintf(stderr, "ERROR: Unable to set system time.\n");
+ RetValue = 1;
+ }
+ else {
+ /* Successfully re-adjusted computer clock */
+ GetLocalTime(&LOCALTime);
+ snprintf(timeBuf, 60, "%s, %02d %s %04d %02d:%02d:%02d.%03d, ",
+ DayStr[LOCALTime.wDayOfWeek], LOCALTime.wDay,
+ MthStr[LOCALTime.wMonth-1], LOCALTime.wYear,
+ LOCALTime.wHour, LOCALTime.wMinute, LOCALTime.wSecond,
+ LOCALTime.wMilliseconds);
+ fprintf(stderr, "\nNew System's Date: %s%s\n", timeBuf, tzoneBuf);
+ }
+ }
+
+ /* Cleanup before exit */
+ conf_init(conf);
+ curl_easy_cleanup(curl);
+ }
+ return RetValue;
+}
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