C# cannot save file from url with proxy

Question

I'm trying to download a file from a url. I try two approachs but it isn't working with external files.

I think it's happening because I have internet over proxy. I can download internal network files (images, mp3, mp4, whatever...) but when I try to download something in external network it gives me timeout or 404 Not Found.

1st approach: System.Net.WebResponse, System.IO.FileStream

     try
        {
            var credentials = new NetworkCredential("myNetworkUserName", "myNetworkPassword", "myNetworkDomain");
            var proxy = WebProxy.GetDefaultProxy(); //new WebProxy("myNetworkProxy") <-- I TRY BOOTH WAYS
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://farm1.static.flickr.com/83/263570357_e1b9792c7a.jpg"); //External image link

            proxy.Credentials = credentials;

            request.Proxy = proxy;

            responseExternalImage = request.GetResponse();//explode here ex=""Unable to connect to the remote server""

            string fileName = GetFileName(response.ResponseUri.OriginalString);
                Stream stream = response.GetResponseStream();

                using (BinaryReader br = new BinaryReader(stream))
                {
                    content = br.ReadBytes(50000000);//perto de 50Mb
                    br.Close();
                }
                response.Close();

                FileStream fs = new FileStream(pathToSaveFile + "\\" + fileName, FileMode.Create);
                BinaryWriter bw = new BinaryWriter(fs);
                try
                {
                    bw.Write(content);
                }
                finally
                {
                    fs.Close();
                    bw.Close();
                }
        }
        catch (Exception ex)
        {

        }

The exception caught at GetResponse() says: "Unable to connect to the remote server", ""A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 77.238.160.184:80""

2nd approach: System.Net.WebClient, DownloadFile

      try
        {
            var credentials = new NetworkCredential("xpta264", ConfigurationManager.AppSettings["Xpta264Password"], "ptsi");
            var proxy = WebProxy.GetDefaultProxy();
            proxy.Credentials = credentials;

            // Create a new WebClient instance.
            using (WebClient myWebClient = new WebClient())
            {
                myWebClient.Proxy = proxy;
                // Download the Web resource and save it into the current filesystem folder.
                myWebClient.DownloadFile("http://farm1.static.flickr.com/83/263570357_e1b9792c7a.jpg", pathToSaveFile + "\\testImage.jpg");
            }
        }
        catch (Exception e)
        {

        }

The exception was caught at DownloadFile method and gives me the same error.

Hope someone can help me.

Sorry for my English

score 0 · Accepted Answer · answered Oct 07 '11 at 16:04

0

WebProxy.GetDefaultProxy() is obsolete and doesn't handle all cases. From the docs:

Note: This API is now obsolete.

The GetDefaultProxy method does not pick up any dynamic settings that are generated from scripts run by Internet Explorer, from automatic configuration entries, or from DHCP or DNS lookups.

Applications should use the WebRequest.DefaultWebProxy property and the WebRequest.GetSystemWebProxy method instead of the GetDefaultProxy method.

A better approach is to try to request a url and see if a proxy was used. I use this code in my own production system and it seems to work pretty well. Once you find the proxy, you can cache the address somewhere:

WebProxy proxy = null;

Uri testUri = new Uri("http://www.example.com/"); // replace with REAL url
Uri proxyEndpoint = WebRequest.GetSystemWebProxy().GetProxy(testUri);
if (!testUri.Equals(proxyEndpoint))
    proxy = new WebProxy(proxyEndPoint.ToString());

You can also just try calling WebRequest.GetSystemWebProxy() and see if that gives you the proxy, but I remember having problems with that which is why I went the request route above. YMMV.

answered Oct 07 '11 at 16:04

mellamokb

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I think I don't understand...What is the url to replace for your "http://www.example.com/"? The proxy url or the url of the file I try to download? In boot ways the 'proxy' variable never was fill... =( – Gelásio Oct 10 '11 at 09:35
proxyEndpoint value is exactly the same than testUri... =/ this means that my proxy is not found, correct? – Gelásio Oct 10 '11 at 13:28
Sounds like your proxy is not being found. You might have to set it up manually before each WebRequest. Does a web browser work on this machine, i.e., does it detect proxy settings properly? – mellamokb Oct 10 '11 at 14:11
Yes, everything is working on web browsers (IE, Firefox and Chrome...) I set up proxy manually doing `var proxy = new WebProxy("myProxyAddress from InternetOptions");` but gives me "The remote server returned an error: (404) Not Found." exception at GetResponse =( – Gelásio Oct 10 '11 at 16:06
Weird.. Are you sure the remote address actually exists? – mellamokb Oct 10 '11 at 16:40
Apparently my problem is even more stranger. I cannot ping any website out of my network. I try in a collegue's computer and the code works without any proxy. I already put this question to my company's helpdesk. =/ – Gelásio Oct 11 '11 at 10:21
**For the record**: I was using "Check Point Endpoint Connect", a VPN application to connect to network. I use it with a standalone application but the same application is available through browser. The standalone application block me internet connection in many ways. When I change to remote acess application in browser everything works perfectly without using any proxy. Thanks for all replys anyway. – Gelásio Oct 13 '11 at 14:28

C# cannot save file from url with proxy

1 Answers1