C# – Big files uploading (WebException: The connection was closed unexpectedly)



See post #3 below.

There is a need to upload a file to the web automatically (without browser). Host – Mini File Host v1.2 (if this does matter). Didn't find specific api in documentation, so at first i sniffed browser requests in Firebug as follows :

Params : do
Value : verify
POST /upload.php?do=verify HTTP/1.1
Host: webfile.ukrwest.net
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.2; ru; rv: Gecko/2009032609 Firefox/3.0.8 (.NET CLR 4.0.20506)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: ru,en-us;q=0.7,en;q=0.3
Accept-Encoding: gzip,deflate
Accept-Charset: windows-1251,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://filehoster.awardspace.com/index.php
Content-Type: multipart/form-data; boundary=---------------------------27368237179714
Content-Length: 445

Content-Disposition: form-data; name="upfile"; filename="Test.file"
Content-Type: application/octet-stream

12345678901011121314151617sample text
Content-Disposition: form-data; name="descr"

Content-Disposition: form-data; name="pprotect"


Here we can see parameter, headers, content type and chunks of information (1 – file name and type, 2 – file contents, 3 – additional params – description and password, not necessarily applied).
So i've created a class that emulates such a behaviour step by step : HttpWebRequest on the url, apply needed parameters to request, form request strings with StringBuilder and convert them to byte arrays, read a file using FileStream, putting all that stuff to MemoryStream and then writing it to request (took major part of a code from an article at CodeProject where it uploads a file to Rapidshare host).
Neat and tidy, but… It doesn't seem to work :(. As result it returns initial upload page, not a result page with links i could parse and present to a user…
Here are main methods of an Uploader class :

// Step 1 - request creation 
 private HttpWebRequest GetWebrequest(string boundary)
            Uri uri = new Uri("http://filehoster.awardspace.com/index.php?do=verify");
            System.Net.HttpWebRequest httpWebRequest = (System.Net.HttpWebRequest)System.Net.WebRequest.Create(uri);
            httpWebRequest.CookieContainer = _cookies;
            httpWebRequest.ContentType = "multipart/form-data; boundary=" + boundary;
            httpWebRequest.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.2; ru; rv: Gecko/2009032609 Firefox/3.0.8 (.NET CLR 4.0.20506)";
            httpWebRequest.Referer = "http://filehoster.awardspace.com/index.php";
            httpWebRequest.Method = "POST";
            httpWebRequest.KeepAlive = true;
            httpWebRequest.Timeout = -1;
            //httpWebRequest.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
            httpWebRequest.Headers.Add("Accept-Charset", "windows-1251,utf-8;q=0.7,*;q=0.7");
            httpWebRequest.Headers.Add("Accept-Encoding", "gzip,deflate");
            httpWebRequest.Headers.Add("Accept-Language", "ru,en-us;q=0.7,en;q=0.3");
            //httpWebRequest.AllowAutoRedirect = true;
            //httpWebRequest.ProtocolVersion = new Version(1,1);
            //httpWebRequest.SendChunked = true;
            //httpWebRequest.Headers.Add("Cache-Control", "no-cache");
            //httpWebRequest.ServicePoint.Expect100Continue = false;
            return httpWebRequest;
// Step 2 - first message part (before file contents)
private string GetRequestMessage(string boundary, string FName, string description, string password)
            System.Text.StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.Append("Content-Disposition: form-data; name=\"");
            stringBuilder.Append("\"; filename=\"");
            stringBuilder.Append("Content-Type: application/octet-stream");
            return stringBuilder.ToString();
// Step 4 - additional request parameters. Step 3 - reading file is in method below
private string GetRequestMessageEnd(string boundary)
            System.Text.StringBuilder stringBuilder = new StringBuilder();
            stringBuilder.Append("Content-Disposition: form-data; name=\"descr\"");
            stringBuilder.Append("Default description");
            stringBuilder.Append("Content-Disposition: form-data; name=\"pprotect\"");
            return stringBuilder.ToString();
// Main method
public string ProcessUpload(string FilePath, string description, string password)
            // Chosen file information
            FileSystemInfo _file = new FileInfo(FilePath);
            // Random boundary generation
            DateTime dateTime2 = DateTime.Now;
            long l2 = dateTime2.Ticks;
            string _generatedBoundary = "----------" + l2.ToString("x");
            // Web request creation
            System.Net.HttpWebRequest httpWebRequest = GetWebrequest(_generatedBoundary);
            // Main app block - form and send request
            using (System.IO.FileStream fileStream = new FileStream(_file.FullName, FileMode.Open, FileAccess.Read, FileShare.Read))
                byte[] bArr1 = Encoding.ASCII.GetBytes("\r\n--" + _generatedBoundary + "\r\n");
                // Generating pre-content post message
                string firstPostMessagePart = GetRequestMessage(_generatedBoundary, _file.Name, description, password);
                // Writing first part of request
                byte[] bArr2 = Encoding.UTF8.GetBytes(firstPostMessagePart);
                Stream memStream = new MemoryStream();
                memStream.Write(bArr1, 0, bArr1.Length);
                memStream.Write(bArr2, 0, bArr2.Length);
                // Writing file
                byte[] buffer = new byte[1024];
                int bytesRead = 0;
                while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
                    memStream.Write(buffer, 0, bytesRead);
                // Generating end of a post message
                string secondPostMessagePart = GetRequestMessageEnd(_generatedBoundary);
                byte[] bArr3 = Encoding.UTF8.GetBytes(secondPostMessagePart);
                memStream.Write(bArr3, 0, bArr3.Length);
                // Preparing to send
                httpWebRequest.ContentLength = memStream.Length;

                Stream requestStream = httpWebRequest.GetRequestStream();

                memStream.Position = 0;
                byte[] tempBuffer = new byte[memStream.Length];
                memStream.Read(tempBuffer, 0, tempBuffer.Length);
                // Sending request
                requestStream.Write(tempBuffer, 0, tempBuffer.Length);
            // Delay (?)
            // Getting response
            string strResponse = "";
            using (Stream stream = httpWebRequest.GetResponse().GetResponseStream())
            using (StreamReader streamReader = new StreamReader(stream/*, Encoding.GetEncoding(1251)*/))
                strResponse = streamReader.ReadToEnd();
            return strResponse;

Plays with ProtocolVersion (1.0, 1.1), AllowAutoRedirect (true/false), even known ServicePoint.Expect100Continue (false) didn't fix an issue. Even a 5sec timeout before getting response (thought in case of a big file it doesn't uploads so quick) didn't help.
Content type "octet-stream" was chosen by purpose to upload any file (could use some switch for most popular jpg/zip/rar/doc etc., but that one seems universal). Boundary is generated randomly from timer ticks, not a big deal. What else? :/
I could give up and forget this, but i feel i'm pretty close to solve and then forget about it :P.
In case you need the whole application to run and debug – here it is (70kb, zipped C# 2.0 VS2k8 solution, no ads, no viruses) :


Best Solution

Update : nope, there is no redirect.


Read RFC2388 few times, rewrote the code and it finally worked (i guess the trouble was in utf-read trailing boundary instead of correct 7 bit ascii). Hooray? Nope :(. Only small files are transfered, big ones throwing "The connection was closed unexpectedly".

System.Net.WebException was unhandled by user code
  Message="The underlying connection was closed: The connection was closed unexpectedly."
   at Uploader.Upload.ProcessUpload(String FilePath, String description, String password) in F:\MyDocuments\Visual Studio 2008\Projects\Uploader\Uploader.cs:line 96
   at Uploader.Form1.backgroundWorker1_DoWork(Object sender, DoWorkEventArgs e) in F:\MyDocuments\Visual Studio 2008\Projects\Uploader\Form1.cs:line 45
   at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument) 

I know that's a bug with .net stack and few solutions exists :

1) increase both Timeout and ReadWriteTimeout of request

2) assign request.KeepAlive = false and System.Net.ServicePointManager.Expect100Continue = false

3) set ProtocolVersion to 1.0 But neither one of them nor all of them altogether help in my case. Any ideas?

EDIT - Source code:

// .. request created, required params applied
httpWebRequest.ProtocolVersion = HttpVersion.Version10; // fix 1
httpWebRequest.KeepAlive = false; // fix 2
httpWebRequest.Timeout = 1000000000; // fix 3
httpWebRequest.ReadWriteTimeout = 1000000000; // fix 4
// .. request processed, data written to request stream
string strResponse = "";            
    using (WebResponse httpResponse = httpWebRequest.GetResponse()) // error here
            using (Stream responseStream = httpResponse.GetResponseStream())
                using (StreamReader streamReader = new StreamReader(responseStream))
                        strResponse = streamReader.ReadToEnd();
catch (WebException exception)
    throw exception;
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