Name: nt126004 Date: 09/26/2001


java version "1.4.0-beta2"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta2-b77)
Java HotSpot(TM) Client VM (build 1.4.0-beta2-b77, mixed mode)


There is a bug in HttpClient.parseHTTPHeader. For refresh requests that
return a 304 responce code (and not chunked) from the server, a content-length
is not sent. However, you guys don't differentiate between responce codes
and kill the keep-alive if content-length is not present.

Due to this bug, one can't use these classes on server side, cause you run
out of sockets very quickly.

here is the code where the bug exists:
sun.net.www.http.HttpClient.parseHTTPHeader(..) {
....
            try
            {
                l = Integer.parseInt(messageheader.findValue("content-length"));
            }
            catch(Exception exception2) { }
            if(keepAliveConnections > 1 && l > 0)
                keepingAlive = true;
            else
            if(keepingAlive)
                keepingAlive = false;
....
}

Run the test program below and examine with netstat -n (on a widnows
platform). You will see, that if the responce from the server is a 304, two
sockets will be used instead of one. Comment out the following line in the
code below to see the program work correctly, using the same socket to fetch
the second image "urlConnection.setRequestProperty("If-Modified-Since","Thu,
13 Sep 2001 16:13:01 GMT");"

netstat -n result when response not 304 but 200:
  TCP 192.168.109.52:2144 66.48.7.21:80 TIME_WAIT

netstat -n result when response is a 304:
 TCP 192.168.109.52:2145 66.48.7.21:80 TIME_WAIT
 TCP 192.168.109.52:2146 66.48.7.21:80 TIME_WAIT




Here is the test program:

import java.net.*;
import java.io.*;

public class test implements Runnable {

public test() {
}
public void run(){
}

public static void main(String[] args) {
try { //some server with an image

doConnection("http://66.48.7.21/images/23.gif");
Thread.sleep(2000);
doConnection("http://66.48.7.21/images/23.gif");
Thread.sleep(3000);

} catch (Exception e) {
e.printStackTrace();
}
}

public static void doConnection(String urlString) throws Exception
{
URL url = new URL(urlString);
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();


String inputLine;

//comment this out to see stats without refresh
urlConnection.setRequestProperty("If-Modified-Since","Thu, 13 Sep 2001 16:13:01 GMT");

urlConnection.connect();
DataInputStream reader = new DataInputStream(urlConnection.getInputStream());
//if not modified
if (urlConnection.getResponseCode() != 304) {
while ((inputLine = reader.readLine()) != null) {
System.out.println(inputLine);
}
}
              else {
                System.out.println("No change to image");
              }
reader.close();
}

}
(Review ID: 132592)
======================================================================