Question

I have a desktop client that sends data to a web server and I can’t seem to get through the proxy server.

Update: I am getting a 407 HTTP error when trying to communicate through the proxy.

When downloading information from my web server, everything is fine. Once the user configures the proxy server (using a dialog box I wrote) the download works fine. But uploading data using org.apache.http.client.HttpClient is not working.

I am configuring the proxy server with code like this after gathering the information from a JDialog.

        System.setProperty("http.proxyHost", proxyHost);
        System.setProperty("http.proxyPort", "" + portNumber);

Now, once we do that, simple downloads work fine. For instance, I have code that reads some xml data from my web server (see below). On the customer’s network the error in my catch block was displayed before the proxy settings were configured and then everything worked fine once the correct proxy was set.

/**
 * Loads a collection of exams from the web site. The URL is determined by
 * configuration or registration since it is State specific.
 */
public static int importExamsWS(StringBuilder msg) {
    try {
        java.net.URL onlineExams = new URL(examURL);
        //Parse the XML data from InputStream and store it.
        return importExams(onlineExams.openStream(), msg);

    } 
    catch (java.net.UnknownHostException noDNS) {
        showError(noDNS, "Unable to connect to proctinator.com to download the exam file.\n"
                + "There is probably a problem with your Internet proxy settings.");
    }
    catch (MalformedURLException | IOException duh) {
        showFileError(duh);
    }
    return 0;
}

However, when I try to SEND data to the web server it is as if the proxy settings are being ignored and an IOException gets thrown. Namely:

org.apache.http.conn.HttpHostConnectException: Connection to http://proctinator.com:8080 refused

Now I know that port 8080 is not blocked by the customer’s web filter because we tested the address in a web browser.

Here is my code for verifying the registration ID entered by the user:
Update: Now I am also setting the proxy in this method.

//Registered is just an enum with ACTIVE, INACTIVE, NOTFOUND, ERROR
public static Registered checkRegistration(int id) throws IOException {    
    httpclient = new DefaultHttpClient();
    Config pref = Config.getConfig(); //stores user-entered proxy settings.
    HttpHost proxy = new HttpHost(pref.getProxyServer(), pref.getProxyPort());
    httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);
    URIBuilder builder = new URIBuilder();
    String path = "/Proctorest/rsc/register/" + id;
    try {
        builder.setScheme("http").setHost(server).setPort(8080).setPath(path);
        URI uri = builder.build();
        System.out.println("Connecting to " + uri.toString());
        HttpGet httpget = new HttpGet(uri);
        HttpResponse response = httpclient.execute(httpget);
        System.out.println(response.getStatusLine().toString());
        if(response.getStatusLine().getStatusCode()==200) {
            String msg = EntityUtils.toString(response.getEntity());
            GUI.globalLog.log(Level.INFO, "Server response to checkRegistration(" + id + "): " + msg);
            return Registered.stringToRegistered(msg);
        }
        else {
            GUI.globalLog.log(Level.INFO, "Server response status code to checkRegistration: " + 
                    response.getStatusLine().getStatusCode());
            return Registered.ERROR;
        }
    }
    catch(java.net.URISyntaxException bad) {
        System.out.println("URI construction error: " + bad.toString());
        return Registered.ERROR;
    }
}

I’m almost positive that the problem is coming from the proxy server configuration, yet the docs for SystemDefaultHttpClient claim that it takes uses System properties for http.proxyHost and http.proxyPort . I know that the properties have been properly set, but I am still getting this authentication error. Viewing the logs generated from my program showed me this:

checkRegistration INFO: Server response status code to checkRegistration: 407 

How do I resolve this authentication error?

Answer 1

I’ll take a shot. If the proxy server is using basic authentication, you could use the following snippet as an example:

DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getCredentialsProvider().setCredentials(
    new AuthScope("PROXY HOST", 8080),
    new UsernamePasswordCredentials("username", "password"));

HttpHost targetHost = new HttpHost("TARGET HOST", 443, "https");
HttpHost proxy = new HttpHost("PROXY HOST", 8080);

httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy); 

If the proxy server is using NTLM authentication, I do not believe NTLM support is available for all proxy server versions (it will work with some NTLM authentication proxy server versions – check if the proxy is using v1 or v2 of NTLM authentication). For reference & workarounds, you can check the following:

http://hc.apache.org/httpcomponents-client-ga/ntlm.html

http://htmlunit.sourceforge.net/ntlm.html

http://devsac.blogspot.com/2010/10/supoprt-for-ntlmv2-with-apache.html

Depending on your proxy server, you may need to look into NTCredentials instead of UserPasswordCredentials.

I would also suggest that you may wish to look into using wireshark to capture network packets and check the response from the proxy server to be absolutely sure what is causing the problem.