C＃上传文件到FTP服务器

Question

I have a problem with uploading files to ftp server. I have a few buttons. Every button uploads different files to the ftp. The first time when a button is clicked the file is uploaded successfully, but the second and later tries fail. It gives me "The operation has timed out". When I close the site and then open it again I can upload again only one file. I am sure that I can override files on the ftp. Here's the code:

protected void btn_export_OnClick(object sender, EventArgs e)
{
  Stream stream = new MemoryStream();

  stream.Position = 0;

  // fill the stream

  bool res = this.UploadFile(stream, "test.csv", "dir");

  stream.Close();
}

private bool UploadFile(Stream stream, string filename, string ftp_dir)
{
        stream.Seek(0, SeekOrigin.Begin);

        string uri = String.Format("ftp://{0}/{1}/{2}", "host", ftp_dir, filename);

        try
        {
            FtpWebRequest reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));

            reqFTP.Credentials = new NetworkCredential("user", "pass");
            reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
            reqFTP.KeepAlive = false;
            reqFTP.UseBinary = true;
            reqFTP.UsePassive = true;
            reqFTP.ContentLength = stream.Length;
            reqFTP.EnableSsl = true; // it's FTPES type of ftp

            int buffLen = 2048;
            byte[] buff = new byte[buffLen];
            int contentLen;

            try
            {
                Stream ftpStream = reqFTP.GetRequestStream();
                contentLen = stream.Read(buff, 0, buffLen);
                while (contentLen != 0)
                {
                    ftpStream.Write(buff, 0, contentLen);
                    contentLen = stream.Read(buff, 0, buffLen);
                }
                ftpStream.Flush();
                ftpStream.Close();
            }
            catch (Exception exc)
            {
                this.lbl_error.Text = "Error:<br />" + exc.Message;
                this.lbl_error.Visible = true;

                return false;
            }
        }
        catch (Exception exc)
        {
            this.lbl_error.Text = "Error:<br />" + exc.Message;
            this.lbl_error.Visible = true;

            return false;
        }

        return true;    
    }

Does anyone have idea what may cause this strange behaviour? I think I'm closing all streams accurately. Could this be related with the ftp server settings? The admin said that the ftp handshake never happened second time.

Answer 1

start with wrapping your Stream creation in a using clause.

        using(Stream stream = new MemoryStream())
        {
            stream.Position = 0;

            // fill the stream

            bool res = this.UploadFile(stream, "test.csv", "dir");

        }

This will make sure that the stream is closed and that any unmanaged resources are disposed, whether an error occurs or not

Answer 2

I used your code, had the same problem, and fixed it.

After you close the stream, you have to read reqFTP response by calling GetResponse() then close the response . Here is the code that fixes the problem:

// Original code
ftpStream.Flush();
ftpStream.Close();

// Here is the missing part that you have to add to fix the problem
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
this.lbl_error.Text = "Response:<br />" + response.StatusDescription;
response.Close();
reqFTP = null;
this.lbl_error.Visible = true;

You don't have to display the response, you can just get it and close it, I am displaying it just for reference.