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  1. JDK
  2. JDK-4325987

Using URLConnection to get an ASP page, lose headers after first attempt

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    • 006
    • generic, x86
    • generic, windows_nt
    • Verified



        Name: krT82822 Date: 03/29/2000


        (see also 4288221, 4237573->4245903)

        java version "1.2.2"
        Classic VM (build JDK-1.2.2-W, native threads, symcjit)

        java version "1.2.2"
        Classic VM (build JDK-1.2.2-001, native threads, symcjit)

        java version "1.2.1"
        Classic VM (build JDK-1.2.1-003, native threads)


        When making multiple http requests using URLConnection to an ASP page that has
        Request.buffer = true, on the first request, the ASP page receives the correct
        headers, but on subsequent requests, the it does not.

        The following servlet shows this. I gets the same ASP page 4 times, passing it
        a "Cookie" header each time. It simply writes the response from the ASP page
        directly into the servlet's response. The ASP page prints out the number of
        cookies it receives, and their names and values. If you run this servlet, and
        access it from a browser, you'll see that the first time, the ASP page got the
        cookie sent from the servlet and the rest of the times it didn't.

        The same exact servlet works fine when run under JDK1.1.8.

        Could this be an instance of the unreproducible 4237573? The difference is
        that that bug was not reproducible on JDK 1.2.1, but mine is!!

        Here's the Java code, a servlet called Test.

        import java.net.*;

        import java.io.*;
        import javax.servlet.*;
        import javax.servlet.http.*;

        public class Test extends HttpServlet
        {
        public String getServletInfo()
        {
        return "Tests problem with URLConnection";
        }

        public void service(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException
        {
        resp.setContentType("text/html");
        PrintWriter out = new PrintWriter(resp.getOutputStream());

        // to do: code goes here.
        String strPage = "";
        int i = 0;

        for (i = 0 ; i < 4 ; i++)
        {
        URLConnection conn = null;
        URL url;
        String strURL = "http://localhost/Test/Test.asp";
        try
        {
                        url = new URL(strURL);
                        conn = url.openConnection();

                        conn.setDoInput(true);
                        conn.setRequestProperty("Cookie", "MyCookie" + "=" + "Test
        Value");

                        strPage = readURL(conn);
                        
                    }
                    catch (IOException e)
                    {
                        e.printStackTrace();
                    }
                    out.write(strPage);

        }
                out.close();
        }

            private String readURL(URLConnection conn)
                throws IOException
            {
                StringBuffer buff = new StringBuffer();
                
                BufferedReader inBuf = new BufferedReader(
                    new InputStreamReader(conn.getInputStream()));

                String strLine = "";
                while ((strLine = inBuf.readLine()) != null)
                    buff.append(strLine + "\n");
                inBuf.close();
                
                return buff.toString();
            }


        }

        Here's the ASP code, which was in an IIS application called Test, in the file
        Test.asp.

        <%Response.Buffer=true%>
        <HTML>
        <HEAD>
        </HEAD>
        <BODY>

        <P>&nbsp;</P>
        <%

        set Cookies = Request.Cookies()
        Response.Write "Request Cookie Count: " & Cookies.Count & "<br>"

        for each cookiename in Request.Cookies
        Response.Write cookiename & ": " & Request.Cookies.Item(cookiename)
        & "<br>"
        next

        %>

        <%
        ' uncomment out this line, and the subsequent GETs will show the cookie!!
        ' Response.Flush
        %>
        </BODY>
        </HTML>

        -----------------------------

        2/10/2000 email from user:

        It's reproducible in the (at least) the three versions I reported it
        against: 1.2.2-W, 1.2.2-001, and 1.2.1-003. It is not reproducible in
        1.1.8, however.

        As for the the bug I reported it to be perhaps an instance of, I
        accidentally copied the wrong number - the one I wanted to mention was
        4245903, not 4237573. Can you please update this in the report so it
        doesn't get out there and confuse other users?

        I hope that someone there will be able to test this with IIS, as it's
        potentially a pretty nast problem for us.

        ----------------------------


        (Review ID: 101095)
        ======================================================================

        3/29/2000 further comments from the user:

        The problem is in the Java 1.2 implementation of the
        sun.net.www.protocol.http.URLConnection object. When issues several
        requests to the same server, on second or subsequent requests all of my
        headers (standard and custom) are sometimes disappearing. I originally
        found this when using the URLConnection to connect to an ASP page, and
        reported the incident, as shown in the email chain below, which became
        Review ID: 101095.

        The problem is that the writeRequests() method that transfers request
        headers contains a retry loop; when a retry is invoked, the headers you
        passed in are thrown away.

        I've verified that this is the problem by decompiling the class in
        question, fixing the bug, and recompiling. My fix is very naive and will
        cause a small amount of performance degradation by making a copy of the
        incoming headers each time a request is issued. The new implementation of
        this method is included below - search for "SSL" - my initials - to see the
        changes I've made.

        Here's my version of sun.net.www.protocol.http.URLConnection.writeRequests
        ():

            private void writeRequests()
                throws IOException
            {
               // SSL = This is what I added to make a copy of the incoming request
                MessageHeader messageheader = new MessageHeader();
                int i = 0;
                String s;
                while((s = requests.getKey(i)) != null)
                {
                    messageheader.add(s, requests.getValue(i));
                    i++;
                }
                if(!setRequests)
                {
                    requests.prepend(method + " " + http.getURLFile() + " " +
        "HTTP/1.0", null);
                    requests.setIfNotSet("User-Agent", userAgent);
                    int j = url.getPort();
                    String s1 = url.getHost();
                    if(j != -1 && j != 80)
                        s1 = s1 + ":" + String.valueOf(j);
                    requests.setIfNotSet("Host", s1);
                    requests.setIfNotSet("Accept", "text/html, image/gif,
        image/jpeg, *; q=.2, */*; q=.2");
                    if(!failedOnce && http.getHttpKeepAliveSet())
                        if(http.usingProxy && !method.equals("POST") &&
        !method.equals("PUT"))
                            requests.set("Proxy-Connection", "keep-alive");
                        else
                        if(!http.usingProxy)
                            requests.set("Connection", "keep-alive");
                    if(http.usingProxy)
                    {
                        AuthenticationInfo authenticationinfo =
        AuthenticationInfo.getProxyAuth(http.getProxyHostUsed(),
        http.getProxyPortUsed());
                        if(authenticationinfo != null &&
        authenticationinfo.supportsPreemptiveAuthorization())
                            requests.setIfNotSet(authenticationinfo.getHeaderName
        (), authenticationinfo.getHeaderValue());
                    }
                    long l = getIfModifiedSince();
                    if(l != 0L)
                    {
                        Date date = new Date(l);
                        requests.setIfNotSet("If-Modified-Since", date.toGMTString
        ());
                    }
                    AuthenticationInfo authenticationinfo1 =
        AuthenticationInfo.getServerAuth(url);
                    if(authenticationinfo1 != null &&
        authenticationinfo1.supportsPreemptiveAuthorization())
                        requests.setIfNotSet(authenticationinfo1.getHeaderName(),
        authenticationinfo1.getHeaderValue());
                    if(poster != null)
                        synchronized(poster)
                        {
                            if(!method.equals("PUT"))
                            {
                                String s2 = "application/x-www-form-urlencoded";
                                requests.setIfNotSet("Content-type", s2);
                            }
                            requests.set("Content-length",
        String.valueOf(poster.size()));
                        }
                    setRequests = true;
                }
                http.writeRequests(requests);
                if(poster != null)
                {
                    poster.writeTo(ps);
                    ps.flush();
                }
                if(ps.checkError())
                {
                    disconnect();
                    if(failedOnce)
                    {
                    // SSL This is what I added to use the original copy of the
        message header if we're retrying
                        requests = messageheader;
                        throw new IOException("Error writing to server");
                    }
                    failedOnce = true;
                    http = getNewClient(url);
                    ps = (PrintStream)http.getOutputStream();
                    connected = true;
                    responses = new MessageHeader();
                    // SSL This is what I added to use the original copy of the
        message header if we're retrying
                    requests = messageheader;
                    setRequests = false;
                    writeRequests();
                }
            }



              jccollet Jean-Christophe Collet (Inactive)
              kryansunw Kevin Ryan (Inactive)
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