Read file from FTP to memory in C#

Question

I want to read a file from a FTP server without downloading it to a local file. I wrote a function but it does not work:

private string GetServerVersion()
{
         


        

Answer 1

Take a look at my FTP class, it might be exactly what you need.

Public Class FTP
        '-------------------------[BroCode]--------------------------
        '----------------------------FTP-----------------------------
        Private _credentials As System.Net.NetworkCredential
        Sub New(ByVal _FTPUser As String, ByVal _FTPPass As String)
            setCredentials(_FTPUser, _FTPPass)
        End Sub
        Public Sub UploadFile(ByVal _FileName As String, ByVal _UploadPath As String)
            Dim _FileInfo As New System.IO.FileInfo(_FileName)
            Dim _FtpWebRequest As System.Net.FtpWebRequest = CType(System.Net.FtpWebRequest.Create(New Uri(_UploadPath)), System.Net.FtpWebRequest)
            _FtpWebRequest.Credentials = _credentials
            _FtpWebRequest.KeepAlive = False
            _FtpWebRequest.Timeout = 20000
            _FtpWebRequest.Method = System.Net.WebRequestMethods.Ftp.UploadFile
            _FtpWebRequest.UseBinary = True
            _FtpWebRequest.ContentLength = _FileInfo.Length
            Dim buffLength As Integer = 2048
            Dim buff(buffLength - 1) As Byte
            Dim _FileStream As System.IO.FileStream = _FileInfo.OpenRead()
            Try
                Dim _Stream As System.IO.Stream = _FtpWebRequest.GetRequestStream()
                Dim contentLen As Integer = _FileStream.Read(buff, 0, buffLength)
                Do While contentLen <> 0
                    _Stream.Write(buff, 0, contentLen)
                    contentLen = _FileStream.Read(buff, 0, buffLength)
                Loop
                _Stream.Close()
                _Stream.Dispose()
                _FileStream.Close()
                _FileStream.Dispose()
            Catch ex As Exception
                MessageBox.Show(ex.Message, "Upload Error: ", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End Try
        End Sub
        Public Sub DownloadFile(ByVal _FileName As String, ByVal _ftpDownloadPath As String)
            Try
                Dim _request As System.Net.FtpWebRequest = System.Net.WebRequest.Create(_ftpDownloadPath)
                _request.KeepAlive = False
                _request.Method = System.Net.WebRequestMethods.Ftp.DownloadFile
                _request.Credentials = _credentials
                Dim _response As System.Net.FtpWebResponse = _request.GetResponse()
                Dim responseStream As System.IO.Stream = _response.GetResponseStream()
                Dim fs As New System.IO.FileStream(_FileName, System.IO.FileMode.Create)
                responseStream.CopyTo(fs)
                responseStream.Close()
                _response.Close()
            Catch ex As Exception
                MessageBox.Show(ex.Message, "Download Error: ", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End Try
        End Sub
        Public Function GetDirectory(ByVal _ftpPath As String) As List(Of String)
            Dim ret As New List(Of String)
            Try
                Dim _request As System.Net.FtpWebRequest = System.Net.WebRequest.Create(_ftpPath)
                _request.KeepAlive = False
                _request.Method = System.Net.WebRequestMethods.Ftp.ListDirectoryDetails
                _request.Credentials = _credentials
                Dim _response As System.Net.FtpWebResponse = _request.GetResponse()
                Dim responseStream As System.IO.Stream = _response.GetResponseStream()
                Dim _reader As System.IO.StreamReader = New System.IO.StreamReader(responseStream)
                Dim FileData As String = _reader.ReadToEnd
                Dim Lines() As String = FileData.Split(New String() {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries)
                For Each l As String In Lines
                    ret.Add(l)
                Next
                _reader.Close()
                _response.Close()
            Catch ex As Exception
                MessageBox.Show(ex.Message, "Directory Fetch Error: ", MessageBoxButtons.OK, MessageBoxIcon.Error)
            End Try
            Return ret
        End Function

        Private Sub setCredentials(ByVal _FTPUser As String, ByVal _FTPPass As String)
            _credentials = New System.Net.NetworkCredential(_FTPUser, _FTPPass)
        End Sub
    End Class

To initialize:

Dim ftp As New FORM.FTP("username", "password")

ftp.UploadFile("c:\file.jpeg", "ftp://domain/file.jpeg")

ftp.DownloadFile("c:\file.jpeg", "ftp://ftp://domain/file.jpeg")

Dim directory As List(Of String) = ftp.GetDirectory("ftp://ftp.domain.net/")
        ListBox1.Items.Clear()
        For Each item As String In directory
            ListBox1.Items.Add(item)
        Next

https://stackoverflow.com/a/28669746/2701974

Answer 2

WebClient request = new WebClient();
string url = "ftp://ftp.microsoft.com/developr/fortran/" +"README.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");
request.Proxy = null;

try
{
  byte[] newFileData = request.DownloadData(url);
  string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
  Console.WriteLine(fileString);
}
catch (WebException e)
{
  // Do something such as log error, but this is based on OP's original code
  // so for now we do nothing.
}

Answer 3

I know this is an old question, but I thought I'd suggest using path.combine for the next guy reading this. Helps clean up these kinds of issues.

        string url = Path.Combine("ftp://ftp.microsoft.com/developr/fortran", "README.TXT");

Answer 4

Small binary file

If the file is small, the easiest way is using WebClient.DownloadData:

WebClient client = new WebClient();
string url = "ftp://ftp.example.com/remote/path/file.zip";
client.Credentials = new NetworkCredential("username", "password");
byte[] contents = client.DownloadData(url);

---

Small text file

If the small file is a text file, use WebClient.DownloadString:

string contents = client.DownloadString(url);

It assumes that the file contents is in UTF-8 encoding (a plain ASCII file will do too). If you need to use a different encoding, use WebClient.Encoding property.

---

Large binary file

If the file is large, so that you need to process it in chunks, instead of loading it to memory whole, use FtpWebRequest:

FtpWebRequest request =
    (FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.zip");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.DownloadFile;

using (Stream stream = request.GetResponse().GetResponseStream())
{
    byte[] buffer = new byte[10240];
    int read;
    while ((read = stream.Read(buffer, 0, buffer.Length)) > 0)
    {
        // process the chunk in "buffer"
    }
}

---

Large text file

If the large file is a text file and you want to process it by lines, instead of by chunks of a fixed size, use StreamReader:

FtpWebRequest request =
    (FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.txt");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.DownloadFile;

using (Stream stream = request.GetResponse().GetResponseStream())
using (StreamReader reader = new StreamReader(stream))
{
    while (!reader.EndOfStream)
    {
        string line = reader.ReadLine();
        // process the line
        Console.WriteLine(line);
    }
}

Again, this assumes UTF-8 encoding. If you want to use another encoding, use an overload of StreamReader constructor that takes also Encoding.

Answer 5

Here's a simple working example using your code to grab a file from the Microsoft public FTP servers:

WebClient request = new WebClient();
string url = "ftp://ftp.microsoft.com/developr/fortran/" +"README.TXT";
request.Credentials = new NetworkCredential("anonymous", "anonymous@example.com");

try
{
  byte[] newFileData = request.DownloadData(url);
  string fileString = System.Text.Encoding.UTF8.GetString(newFileData);
  Console.WriteLine(fileString);
}
catch (WebException e)
{
  // Do something such as log error, but this is based on OP's original code
  // so for now we do nothing.
}

I reckon you're missing a slash on this line here in your code:

string url = FtpPath + FileName;

Perhaps between FtpPath and FileName ?

Answer 6

It is impossible to know what the issue is without details about the error/exception.

At a guess, you do not seem to be assigning a new value to version after the initial declaration

string version = "";

Try changing your code to

version = System.Text.Encoding.UTF8.GetString(newFileData);