C# Getting proxy settings from Internet Explorer

Question

i have a problem in certain company in germany. They use proxy in their network and my program cant communicate with server.

IE works with this settings:

It means: Automatically detect settings

This is the code:

public static bool CompleteValidation(string regKey)
{
    string uri = "***";

    int c = 1;
    if (Counter < 5) c = 6 - Counter;
    string response = "";
    try
    {
        System.Net.ServicePointManager.Expect100Continue = false;
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(uri);
        request.AllowWriteStreamBuffering = true;
        request.Method = "POST";
        request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0) Gecko/20100101 Firefox/5.0";
        request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
        request.Headers.Add(HttpRequestHeader.AcceptLanguage, "pl,en-us;q=0.7,en;q=0.3");
        request.Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip, deflate");
        request.Headers.Add(HttpRequestHeader.AcceptCharset, "ISO-8859-2,utf-8;q=0.7,*;q=0.7");
        request.KeepAlive = true;

        //proxy settings
        string exepath = Path.GetDirectoryName(Application.ExecutablePath);
        string proxySettings = exepath + @"\proxy.ini";
        WebProxy wp = new WebProxy();
        if (File.Exists(proxySettings)) {
            request.Proxy = WebRequest.DefaultWebProxy;
            IniFile ini = new IniFile(proxySettings);
            string user = ini.IniReadValue("Proxy", "User");
            string pass = ini.IniReadValue("Proxy", "Password");
            string domain = ini.IniReadValue("Proxy", "Domain");
            string ip = ini.IniReadValue("Proxy", "IP");
            string port_s = ini.IniReadValue("Proxy", "Port");
            int port = 0;
            if (!string.IsNullOrEmpty(ip))
            {
                if (!string.IsNullOrEmpty(port_s))
                {
                    try
                    {
                        port = Convert.ToInt32(port_s);
                    }
                    catch (Exception e)
                    {
                        ErrorLog.AddToLog("Problem with conversion of port:");
                        ErrorLog.AddToLog(e.Message);
                        ErrorLog.ShowLogWindow();
                    }
                    wp = new WebProxy(ip, port);
                } else {
                    wp = new WebProxy(ip);
                }

            }
            if (string.IsNullOrEmpty(domain))
                wp.Credentials = new NetworkCredential(user, pass);
            else
                wp.Credentials = new NetworkCredential(user, pass, domain);
            request.Proxy = wp;
        }

        string post = "***";
        request.ContentLength = post.Length;
        request.ContentType = "application/x-www-form-urlencoded";
        StreamWriter writer = null;
        try
        {
            writer = new StreamWriter(request.GetRequestStream()); // Here is the WebException thrown
            writer.Write(post);
            writer.Close();
        }
        catch (Exception e)
        {
            ErrorLog.AddToLog("Problem with request sending:");
            ErrorLog.AddToLog(e.Message);
            ErrorLog.ShowLogWindow();
        }
        HttpWebResponse Response = null;
        try 
        {
           Response  = (HttpWebResponse)request.GetResponse();
        }
        catch (Exception e)
        {
            ErrorLog.AddToLog("Problem with response:");
            ErrorLog.AddToLog(e.Message);
            ErrorLog.ShowLogWindow();
        }

        //Request.Proxy = WebProxy.GetDefaultProxy();
        //Request.Proxy.Credentials = CredentialCache.DefaultCredentials;
        string sResponseHeader = Response.ContentEncoding; // get response header

        if (!string.IsNullOrEmpty(sResponseHeader))
        {
            if (sResponseHeader.ToLower().Contains("gzip"))
            {
                byte[] b = DecompressGzip(Response.GetResponseStream());
                response = System.Text.Encoding.GetEncoding(Response.ContentEncoding).GetString(b);
            }
            else if (sResponseHeader.ToLower().Contains("deflate"))
            {
                byte[] b = DecompressDeflate(Response.GetResponseStream());
                response = System.Text.Encoding.GetEncoding(Response.ContentEncoding).GetString(b);
            }
        }
        // uncompressed, standard response
        else
        {
            StreamReader ResponseReader = new StreamReader(Response.GetResponseStream());
            response = ResponseReader.ReadToEnd();
            ResponseReader.Close();
        }
    }
    catch (Exception e)
    {
        ErrorLog.AddToLog("Problem with comunication:");
        ErrorLog.AddToLog(e.Message);
        ErrorLog.ShowLogWindow();
    }

    if (response == "***")
    {
        SaveKeyFiles();
        WriteRegKey(regKey);
        RenewCounter();
        return true;
    }
    else
    {
        return false;
    }

}

My program logs it as:

[09:13:18] Searching for hardware ID
[09:13:56] Problem with response:
[09:13:56] The remote server returned an error: (407) Proxy Authentication Required.
[09:15:04] problem with comunication:
[09:15:04] Object reference not set to an object instance.

If they write user and pass into proxy.ini file, program works. But the problem is they cant do that. And somehow IE works without it. Is there any way to get those settings from IE or system?

Answer 1

Use GetSystemWebProxy to return what the system default proxy is.

    WebRequest.DefaultProxy = WebRequest.GetSystemWebProxy();

But every HttpWebRequest should automatically be filled out with this information by default. For example, the following snippet in a standalone console application should print the correct information on a system with a PAC file configured.

    HttpWebRequest myWebRequest=(HttpWebRequest)WebRequest.Create("http://www.microsoft.com");

    // Obtain the 'Proxy' of the  Default browser.  
    IWebProxy proxy = myWebRequest.Proxy;
    // Print the Proxy Url to the console.
    if (proxy != null)
    {
        Console.WriteLine("Proxy: {0}", proxy.GetProxy(myWebRequest.RequestUri));
    } 
    else
    {
        Console.WriteLine("Proxy is null; no proxy will be used");
    }

Answer 2

Use DefaultNetworkCredentials to return system proxy credentials.

request.Proxy.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;