Made cache checking easier.

[jsvc.git] / src / dolda / jsvc / util / Cache.java

package dolda.jsvc.util;

import dolda.jsvc.*;
import java.util.*;

public class Cache {
    public static void checkmtime(Request req, long mtime) {
	/* Since the HTTP time format is (reasonably enough) precise
	 * only to seconds, any extra milliseconds must be trimmed
	 * off, or the mtime will almost certainly not match. */
	Date mdate = new Date((mtime / 1000) * 1000);
	String ims = req.inheaders().get("If-Modified-Since");
	if(ims != null) {
	    Date cldate;
	    try {
		cldate = Http.parsedate(ims);
	    } catch(java.text.ParseException e) {
		throw(Restarts.stdresponse(400, "The If-Modified-Since header is not parseable."));
	    }
	    if(mdate.compareTo(cldate) <= 0) {
		req.status(304);
		req.outheaders().put("Content-Length", "0");
		throw(Restarts.done());
	    }
	}
	req.outheaders().put("Last-Modified", Http.fmtdate(mdate));
    }
}