-const char cgi_rcs[] = "$Id: cgi.c,v 1.70.2.13 2004/02/17 13:30:23 oes Exp $";
+const char cgi_rcs[] = "$Id: cgi.c,v 1.72 2006/07/18 14:48:45 david__schmidt Exp $";
/*********************************************************************
*
- * File : $Source: /cvsroot/ijbswa/current/Attic/cgi.c,v $
+ * File : $Source: /cvsroot/ijbswa/current/cgi.c,v $
*
* Purpose : Declares functions to intercept request, generate
* html or gif answers, and to compose HTTP resonses.
*
* Revisions :
* $Log: cgi.c,v $
+ * Revision 1.72 2006/07/18 14:48:45 david__schmidt
+ * Reorganizing the repository: swapping out what was HEAD (the old 3.1 branch)
+ * with what was really the latest development (the v_3_0_branch branch)
+ *
* Revision 1.70.2.13 2004/02/17 13:30:23 oes
* Moved cgi_error_disabled() from cgiedit.c to
* cgi.c to re-enable build with --disable-editor.
else
{
/*
- * Compliant browsers should not cache this due to the "Cache-Control"
- * setting. However, to be certain, we also set both "Last-Modified"
- * and "Expires" to the current time.
+ * Setting "Cache-Control" to "no-cache" and "Expires" to
+ * the current time doesn't exactly forbid caching, it just
+ * requires the client to revalidate the cached copy.
+ *
+ * If a temporary problem occurres and the user tries again after
+ * getting Privoxy's error message, a compliant browser may set the
+ * If-Modified-Since header with the content of the error page's
+ * Last-Modified header. More often than not, the document on the server
+ * is older than Privoxy's error message, the server would send status code
+ * 304 and the browser would display the outdated error message again and again.
+ *
+ * As a last resort we set "Last-Modified" to Tim Berners-Lee's birthday,
+ * which predates the age of any page on the web and can be safely used to
+ * "revalidate" without getting a status code 304.
+ *
+ * There is no need to let the useless If-Modified-Since header reach the
+ * server, it is therefore stripped by client_if_modified_since in parsers.c.
*/
if (!err) err = enlist_unique_header(rsp->headers, "Cache-Control", "no-cache");
get_http_time(0, buf);
if (!err) err = enlist_unique_header(rsp->headers, "Date", buf);
- if (!err) err = enlist_unique_header(rsp->headers, "Last-Modified", buf);
+ if (!err) err = enlist_unique_header(rsp->headers, "Last-Modified", "Wed, 08 Jun 1955 12:00:00 GMT");
if (!err) err = enlist_unique_header(rsp->headers, "Expires", "Sat, 17 Jun 2000 12:00:00 GMT");
+ if (!err) err = enlist_unique_header(rsp->headers, "Pragma", "no-cache");
}