FiddlerScript: lint caching headers (to be put in OnPeekAtResponseHeaders)

gistfile1.txt

	static function checkForInvalidCachingHeaders(oSession: Session) {
		// var _temp : int = 0;
		// 	&& !(int.TryParse(oSession.oResponse["Expires"], out _temp))
		
		if (oSession.oResponse.headers.Exists("Expires")
		  && oSession.oResponse.headers.Exists("Date")
		  && oSession.oResponse.headers.ExistsAndContains("Cache-Control", "max-age"))
		{
			try {
				var ageSeconds : Int64 = 0;
				var ageHours : Int64 = 0;
				if (oSession.oResponse.headers.Exists("Age")) {
					ageSeconds = Int64.Parse(oSession.oResponse["Age"]);
					ageHours = Convert.ToInt64(ageSeconds / 3600);
				}
						
				var expiresDiff : TimeSpan = DateTime.Parse(oSession.oResponse["Expires"]) - DateTime.Parse(oSession.oResponse["Date"]);
				var expiresHours : Int64 = Convert.ToInt64((expiresDiff.TotalHours + ageHours));
								
				var cacheControl : String = oSession.oResponse["Cache-Control"];
				var match : System.Text.RegularExpressions.Match = System.Text.RegularExpressions.Regex.Match(cacheControl, "max-age=([0-9]+)");
				var cacheControlSeconds : Int64 = Int64.Parse(match.Groups[1].Value);			
				var cacheControlHours : Int64 = Convert.ToInt64((cacheControlSeconds / 3600));
							
				if (expiresHours > 0
					&& cacheControlHours > 0
					&& expiresHours != cacheControlHours
					&& (expiresHours > 1.2 * cacheControlHours || expiresHours < 0.8 * cacheControlHours)
				) {
					oSession["ui-backcolor"] = "purple";
					oSession["ui-color"] = "white";
					oSession["ui-Comments"] = "cacheControlHrs=" + cacheControlHours + "; expiresHrs=" + expiresHours;
					oSession.RefreshUI();
				}
			} catch(ex) {
				oSession["ui-Comments"] = ex.ToString();
			}
		} //endif invalid caching headers
	}