Develop Reference

File size detection before downloading from an ftp server? C# error

I have a C# homework, to create a download manager to download a file from an ftp server, with these conditions:
Selection of an audio file on a server.
Detection of file size.
Asynchronous transmission of the file to your work PC via ftp.
Representation of the progress of the download.
Actually, I have completed three of them, almost all, except some error occured with the second condition when I tried to get the file size before downloading, my program crashed and an error happened like this:
Error
This is the code for my downloader:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Net;
namespace DownloadDataFTP
{
public partial class ftpForm : Form
{
public ftpForm()
{
InitializeComponent();
}
private byte[] downloadedData;
//Connects to the FTP server and downloads the file
private void downloadFile(string FTPAddress, string filename, string username, string password)
{
downloadedData = new byte[0];
try
{
//Create FTP request
//Note: format is ftp://server.com/file.ext
FtpWebRequest request = FtpWebRequest.Create(FTPAddress + "/" + filename) as FtpWebRequest;
//Get the file size first (for progress bar)
request.Method = WebRequestMethods.Ftp.GetFileSize;
request.Credentials = new NetworkCredential(username, password);
request.UsePassive = true;
request.UseBinary = true;
request.KeepAlive = true; //don't close the connection
int dataLength = (int)request.GetResponse().ContentLength;
//Now get the actual data
request = FtpWebRequest.Create(FTPAddress + "/" + filename) as FtpWebRequest;
request.Method = WebRequestMethods.Ftp.DownloadFile;
request.Credentials = new NetworkCredential(username, password);
request.UsePassive = true;
request.UseBinary = true;
request.KeepAlive = false; //close the connection when done
//Set up progress bar
progressBar1.Value = 0;
progressBar1.Maximum = dataLength;
lbProgress.Text = "0/" + dataLength.ToString();
//Streams
FtpWebResponse response = request.GetResponse() as FtpWebResponse;
Stream reader = response.GetResponseStream();
//Download to memory
//Note: adjust the streams here to download directly to the hard drive
MemoryStream memStream = new MemoryStream();
byte[] buffer = new byte[1024]; //downloads in chuncks
while (true)
{
Application.DoEvents(); //prevent application from crashing
//Try to read the data
int bytesRead = reader.Read(buffer, 0, buffer.Length);
if (bytesRead == 0)
{
//Nothing was read, finished downloading
progressBar1.Value = progressBar1.Maximum;
lbProgress.Text = dataLength.ToString() + "/" + dataLength.ToString();
Application.DoEvents();
break;
}
else
{
//Write the downloaded data
memStream.Write(buffer, 0, bytesRead);
//Update the progress bar
if (progressBar1.Value + bytesRead <= progressBar1.Maximum)
{
progressBar1.Value += bytesRead;
lbProgress.Text = progressBar1.Value.ToString() + "/" + dataLength.ToString();
progressBar1.Refresh();
Application.DoEvents();
}
}
}
//Convert the downloaded stream to a byte array
downloadedData = memStream.ToArray();
//Clean up
reader.Close();
memStream.Close();
response.Close();
MessageBox.Show("Downloaded Successfully");
}
catch (Exception)
{
MessageBox.Show("There was an error connecting to the FTP Server.");
}
txtData.Text = downloadedData.Length.ToString();
this.Text = "Download and Upload Data through FTP";
username = string.Empty;
password = string.Empty;
}
//Upload file via FTP
private void Upload(string FTPAddress, string filePath, string username, string password)
{
//Create FTP request
FtpWebRequest request = (FtpWebRequest)FtpWebRequest.Create(FTPAddress + "/" + Path.GetFileName(filePath));
request.Method = WebRequestMethods.Ftp.UploadFile;
request.Credentials = new NetworkCredential(username, password);
request.UsePassive = true;
request.UseBinary = true;
request.KeepAlive = false;
//Load the file
FileStream stream = File.OpenRead(filePath);
byte[] buffer = new byte[stream.Length];
stream.Read(buffer, 0, buffer.Length);
stream.Close();
//Upload file
Stream reqStream = request.GetRequestStream();
reqStream.Write(buffer, 0, buffer.Length);
reqStream.Close();
MessageBox.Show("Uploaded Successfully");
}
//get file size for downloading
private void FileSize_down(string FTPAddress, string filename)
{
FtpWebRequest request = FtpWebRequest.Create(FTPAddress + "/" + filename) as FtpWebRequest;
request.Method = WebRequestMethods.Ftp.GetFileSize;
long dataLength = (long)request.GetResponse().ContentLength;
sizeFile.Text = dataLength.ToString();
}
//get file size for uploading
private void FileSize_up(string filename)
{
if (UpFile.Text != "")
{
//direction file
FileInfo f = new FileInfo(UpFile.Text);
//add size to text box
textBox1.Text = f.Length.ToString();
}
else
MessageBox.Show("Choose file to upload");
}
//Connects to the FTP server and request the list of available files
private void getFileList(string FTPAddress, string username, string password)
{
List<string> files = new List<string>();
try
{
//Create FTP request
FtpWebRequest request = FtpWebRequest.Create(FTPAddress) as FtpWebRequest;
request.Method = WebRequestMethods.Ftp.ListDirectory;
request.Credentials = new NetworkCredential(username, password);
request.UsePassive = true;
request.UseBinary = true;
request.KeepAlive = false;
FtpWebResponse response = request.GetResponse() as FtpWebResponse;
Stream responseStream = response.GetResponseStream();
StreamReader reader = new StreamReader(responseStream);
while (!reader.EndOfStream)
{
Application.DoEvents();
files.Add(reader.ReadLine());
}
//Clean-up
reader.Close();
responseStream.Close(); //redundant
response.Close();
}
catch (Exception)
{
MessageBox.Show("There was an error connecting to the FTP Server");
}
username = string.Empty;
password = string.Empty;
this.Text = "Download and Upload Data through FTP"; //Back to normal title
//If the list was successfully received, display it to the user
//through a dialog
if (files.Count != 0)
{
listDialogForm dialog = new listDialogForm(files);
if (dialog.ShowDialog() == DialogResult.OK)
{
//Update the File Name field
txtFileName.Text = dialog.ChosenFile;
}
}
}
//Make sure the FTP server address has ftp:// at the beginning
private void txtFTPAddress_Leave(object sender, EventArgs e)
{
if (!txtFTPAddress.Text.StartsWith("ftp://"))
txtFTPAddress.Text = "ftp://" + txtFTPAddress.Text;
}
This is the part that gets file size for download.
//get file size for downloading
private void FileSize_down(string FTPAddress, string filename)
{
FtpWebRequest request = FtpWebRequest.Create(FTPAddress + "/" + filename) as FtpWebRequest;
request.Method = WebRequestMethods.Ftp.GetFileSize;
long dataLength = (long)request.GetResponse().ContentLength;
sizeFile.Text = dataLength.ToString();
}
Thanks so much!

You are getting a 530 (not logged in) error. Seems like that is the issue. In your other methods(downloadFile, getFileList, etc) you include:
request.Credentials = new NetworkCredential(username, password);
request.UsePassive = true;
request.UseBinary = true;
request.KeepAlive = false;
in your Filesize_down you do not.

Why Ftp Downloading is so slow with c# / FtpWebRequest

I'm using the FTP function in c# in order to download somes files.
My problem is that the download is slow.
I don't have any problem with Filezilla, and my connection is OK.
I'm thinking about the FTP functions implementations, here is my code :
public static string DownloadFromList(string strParam,string filePath)
{
string[] FilesToDownload = strParam.Split('\n');
try
{
FtpWebRequest reqFTP;
foreach(string file in FilesToDownload)
{
string tmpfile = file;
if (tmpfile.Contains("\n"))
{
tmpfile = tmpfile.Replace('\n', ' ');
}
FileInfo fileToDownload = new FileInfo(tmpfile);
tmpfile = fileToDownload.Name;
FileStream outputStream = new FileStream(filePath.Trim() + "\\" + tmpfile.Trim(), FileMode.Create);
if (strDirectory.Trim() != "")
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + strHost.Trim() + "/" + strDirectory.Trim() + "/" + tmpfile.Trim()));
}
else
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + strHost.Trim() + "/" + tmpfile.Trim()));
}
reqFTP.ConnectionGroupName = "MyGroupName";
reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
reqFTP.UseBinary = true;
reqFTP.KeepAlive = true;
reqFTP.Timeout = -1;
reqFTP.Credentials = new NetworkCredential(strUser.Trim(), strPass.Trim());
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream();
StreamReader reader = new StreamReader(ftpStream, System.Text.Encoding.UTF8);
long cl = response.ContentLength;
int bufferSize = 8192;
char[] bytesInStream = new char[8192];
int readCount;
StreamWriter sw = new StreamWriter(outputStream);
int len;
while ((len = reader.Read(bytesInStream, 0, bytesInStream.Length)) > 0)
{
sw.Write(bytesInStream, 0, len);
}
sw.Close();
outputStream.Close();
ftpStream.Close();
response.Close();
}
return "ok";
}
catch (Exception ex)
{
return (ex.Message);
}
}
Is it necessary to set useBinary = true ?
KeepAlive is setted to true in order to use the same connection, but is it true ?
Is it possible to set the credential only one time ?
How can i improve this please?
Thanks a lot :)
Best regards,

FTP:Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host

I'm newbie to FTP.I am trying to write to a file in FTP using StreamWriter.Once after writing to the file,i dont want to close the stream as i have some work which has to be done.Later after some 1 hour,if i try to write using the same streamWriter i get the above error.
Below is my code snippet
public void WriteToFTP()
{
bool isConnectionEstablished = false;
StreamWriter stream = null;
try
{
for (int i = 1; i < 5; i++)
{
string message = string.Format("File - {0}.", i.ToString());
if (!isConnectionEstablished)
{
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(new Uri("My FTP path"));
request.Credentials = new NetworkCredential("asdf", "asdf#123");
request.Proxy = null;
request.UseBinary = true;
request.ConnectionGroupName = string.Empty;
request.UsePassive = true;
request.EnableSsl = false;
isConnectionEstablished = true;
stream = new StreamWriter(request.GetRequestStream()) { AutoFlush = true };
}
stream.WriteLine(message);//Here i am getting the error for the i = 2(after doing my work)
//Doing work which may take more than 1 hour.
}
}
catch (Exception exe)
{
//The Error "Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host" is being caught here.
}
finally
{
if (stream != null)
stream.Close();
}
}

you must set timout to infinity,-1 is the value for infinity, see this example:
FtpWebRequest reqFTP;
string fileName = #"c:\downloadDir\localFileName.txt";
FileInfo downloadFile = new FileInfo(fileName);
string uri = "ftp://ftp.myftpsite.com/ftpDir/remoteFileName.txt";
FileStream outputStream = new FileStream(fileName, FileMode.Append);
reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));
reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
reqFTP.UseBinary = true;
reqFTP.KeepAlive = false;
reqFTP.Timeout = -1;
reqFTP.UsePassive = true;
reqFTP.Credentials = new NetworkCredential("userName", "passWord");
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream();
long cl = response.ContentLength;
int bufferSize = 2048;
int readCount;
byte[] buffer = new byte[bufferSize];
readCount = ftpStream.Read(buffer, 0, bufferSize);
Console.WriteLine("Connected: Downloading File");
while (readCount > 0)
{
outputStream.Write(buffer, 0, readCount);
readCount = ftpStream.Read(buffer, 0, bufferSize);
Console.WriteLine(readCount.ToString());
}
ftpStream.Close();
outputStream.Close();
response.Close();
Console.WriteLine("Downloading Complete");

FtpWebRequest while writing to stream if network goes down then FTP Server gives access denied problem when tried to re upload

I am using FtpWebRequest to upload a file.
Facing a problem of which i am not getting solution.
While uploading a heavy file if network get disconnected then FTP server acquires lock on file being uploaded, now when user tries to re upload the same file then it get access denied error.
I have set TimeOut and ReadWriteTimeOut to 5 secs of FtpWebRequest on FTP Server it is 10 secs.
Even if i try to upload same file after an Hour then also same problem exist.
// Get the object used to communicate with the server.
request = (FtpWebRequest)WebRequest.Create(new Uri("ftp://" + FtpInfo.FtpServer.Trim() + "/" + FtpInfo.FtpFolderPath.Trim() + "/" + FileName.Trim()));
request.Method = WebRequestMethods.Ftp.UploadFile;
request.Proxy = null;
// FTP site uses anonymous logon.
request.Credentials = new NetworkCredential(FtpInfo.UserNameForFTP.Trim(), FtpInfo.PasswordForFTP.Trim());
request.UsePassive = FtpInfo.UsePassive;
request.KeepAlive = FtpInfo.KeepAlive;
request.Timeout = FtpInfo.TimeOut; //Milliseconds
request.UseBinary = true;
request.ReadWriteTimeout = FtpInfo.TimeOut; //Milliseconds
FileInfo fi = new FileInfo(SourceLocation);
long length = fi.Length;
BytesUploaded = length;
long uploadSize = 0;
if (chunks == 0)
{
chunks = 1024;
}
else
{
buffLength = chunks;
}
byte[] buff = new byte[buffLength];
int contentLen;
using (FileStream fs = fi.OpenRead())
{
using (Stream strm = request.GetRequestStream())
{
contentLen = fs.Read(buff, 0, buffLength);
try
{
while (contentLen != 0)
{
Dispatcher.Invoke(DispatcherPriority.Normal, (Action)delegate() { lblProgress.Content = "Uploading '" + FileName + "'......" + "Bytes Uploaded (" + uploadSize.ToString() + "/" + length.ToString() + ")"; });
strm.Write(buff, 0, contentLen);
uploadSize += contentLen;
contentLen = fs.Read(buff, 0, buffLength);
}
strm.Close();
}
catch (Exception ex)
{
if (strm!=null)
{
try
{
strm.Close();
}
catch
{
throw ex;
}
}
throw ex;
}
}
fs.Close();
}
try
{
//requestStream.Close(); -orignal
fi = null;
request=null;
}
catch { }

I don't know enough about your app (is the FTP upload on a separate thread for example) but try this:
bool DoneOK = false;
FtpWebRequest request = null;
FtpWebResponse response = null;
try {
// Get the object used to communicate with the server.
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(new Uri("ftp://" + FtpInfo.FtpServer.Trim() + "/" + FtpInfo.FtpFolderPath.Trim() + "/" + FileName.Trim()));
request.Method = WebRequestMethods.Ftp.UploadFile;
request.Proxy = null;
// FTP site uses anonymous logon.
request.Credentials = new NetworkCredential(FtpInfo.UserNameForFTP.Trim(), FtpInfo.PasswordForFTP.Trim());
request.UsePassive = FtpInfo.UsePassive;
request.KeepAlive = FtpInfo.KeepAlive;
request.Timeout = FtpInfo.TimeOut; //Milliseconds
request.UseBinary = true;
request.ReadWriteTimeout = FtpInfo.TimeOut; //Milliseconds
long length = new FileInfo(SourceLocation).Length;
long uploadSize = 0;
if ( chunks < 1 )
chunks = 1024;
buffLength = chunks;
byte[] buff = new byte[buffLength];
int contentLen = 0;
string MSG = "";
using (FileStream fs = File.OpenRead (SourceLocation))
using (Stream strm = request.GetRequestStream())
{
while ((contentLen = fs.Read(buff, 0, buffLength)) > 0 )
{
MSG = "Uploading '" + FileName + "'......" + "Bytes Uploaded (" + uploadSize.ToString() + "/" + length.ToString() + ")";
string tmp_MSG = MSG;
Dispatcher.Invoke(DispatcherPriority.Normal, () => { lblProgress.Content = tmpMSG; });
strm.Write(buff, 0, contentLen);
uploadSize += contentLen;
};
strm.Close();
// necessary - the upload occurs really here !
response = (FtpWebResponse) request.GetResponse();
// check the response codes... for example FileActionOK...
if ( response.StatusCode == System.Net.FtpStatusCode.FileActionOK )
DoneOK = true;
response.Close(); response = null;
request = null;
}
}
catch
{
};
if ( request != null )
{
if ( response != null )
{
try { response.Close(); } catch {};
response = null;
}
if ( !DoneOK )
{
try { request.Abort (); } catch {};
}
request = null;
}

This was problem related to the FTP Server we were using, when we switched FTP server to IIS then everything worked smoothly.
Thanks for all the help

How to download FTP files with automatic resume in case of disconnect

I can download FTP files, but the download code does not have a resume facility and multi part files download. Because there are file larger than 500 MB, I can't download them continuously, because the connection gets closed and it starts download from beginning. I wanted my code a resume facility if it gets disconnected.
The code I am using is:
public string[] GetFileList()
{
string[] downloadFiles;
StringBuilder result = new StringBuilder();
FtpWebRequest reqFTP;
try
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create(
new Uri("ftp://" + ftpServerIP + "/"));
reqFTP.UseBinary = true;
reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
WebResponse response = reqFTP.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream());
//MessageBox.Show(reader.ReadToEnd());
string line = reader.ReadLine();
while (line != null)
{
result.Append(line);
result.Append("\n");
line = reader.ReadLine();
}
result.Remove(result.ToString().LastIndexOf('\n'), 1);
reader.Close();
response.Close();
//MessageBox.Show(response.StatusDescription);
return result.ToString().Split('\n');
}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show(ex.Message);
downloadFiles = null;
return downloadFiles;
}
}
private void Download(string filePath, string fileName)
{
FtpWebRequest reqFTP;
try
{
//filePath = <<The full path where the file is to be created.>>,
//fileName = <<Name of the file to be created
// (Need not be the name of the file on FTP server).>>
FileStream outputStream =
new FileStream(filePath + "\\" + fileName, FileMode.Create);
reqFTP = (FtpWebRequest)FtpWebRequest.Create(
new Uri("ftp://" + ftpServerIP + "/" + fileName));
reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
reqFTP.UseBinary = true;
reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream();
long cl = response.ContentLength;
int bufferSize = 2048;
int readCount;
byte[] buffer = new byte[bufferSize];
readCount = ftpStream.Read(buffer, 0, bufferSize);
while (readCount > 0)
{
outputStream.Write(buffer, 0, readCount);
readCount = ftpStream.Read(buffer, 0, bufferSize);
}
ftpStream.Close();
outputStream.Close();
response.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}

Before you start downloading check for the existence of the file on the local filesystem. If it exists, then get the size and use that for the ContentOffset member of the FtpWebRequest object. This functionality may not be supported by the FTP server, though.

A native implementation of FTP download resumption using the FtpWebRequest:
bool resume = false;
do
{
try
{
FileMode mode = resume ? FileMode.Append : FileMode.Create;
resume = false;
using (Stream fileStream = File.Open(#"C:\local\path\file.dat", mode))
{
var url = "ftp://ftp.example.com/remote/path/file.dat";
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(url);
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.DownloadFile;
request.ContentOffset = fileStream.Position;
using (Stream ftpStream = request.GetResponse().GetResponseStream())
{
ftpStream.CopyTo(fileStream);
}
}
}
catch (WebException)
{
resume = true;
}
}
while (resume);
Or use an FTP library that can resume the transfer automatically.
For example WinSCP .NET assembly does. With it, a resumable download is as trivial as:
// Setup session options
var sessionOptions = new WinSCP.SessionOptions
{
Protocol = Protocol.Ftp,
HostName = "ftp.example.com",
UserName = "user",
Password = "mypassword"
};
using (var session = new Session())
{
// Connect
session.Open(sessionOptions);
// Resumable download
session.GetFileToDirectory("/home/user/file.zip", #"C:\path");
}
(I'm the author of WinSCP)