asp.netvb.netftpclientftp-server

Zero size files uploaded with FTP FileUpload


I've been reading gobs of articles on FTP upload in ASP.NET recently and they all seem to make sense, but every time I've tried implementing them I either get an empty file uploaded, or no file at all. Here are some of the articles I've been reading:

They're all great articles, but like I said, having issues :(

I know exactly what the problem is but I don't know how to fix it. I can pass the file name from the FileUpload control, but the path does not exist for security concerns. However, the StreamReader object requires the fully qualified path of the file to be uploaded, so how the heck do I get that? I'm at my wits end! >.<

Let's use the example by John Peterson that I linked above. Here's the code:

Protected Sub btnUploadFile_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim myFtpWebRequest As FtpWebRequest
    Dim myFtpWebResponse As FtpWebResponse
    Dim myStreamWriter As StreamWriter

    myFtpWebRequest = WebRequest.Create("ftp://ftp_server_name/filename.ext")
    myFtpWebRequest.Method = WebRequestMethods.Ftp.UploadFile
    myFtpWebRequest.UseBinary = True

    myStreamWriter = New StreamWriter(myFtpWebRequest.GetRequestStream())

    'IT BREAKS HERE BECAUSE THE CLIENT PATH IS WRONG!!
    myStreamWriter.Write(New StreamReader(Server.MapPath("filename.ext")).ReadToEnd)
    myStreamWriter.Close()

    myFtpWebResponse = myFtpWebRequest.GetResponse()
    myFtpWebResponse.Close()
End Sub

See? No data in the uploaded file :(

enter image description here

Now my latest implementation looks like this, but the uploaded file is much larger than the source, and corrupted. Seriously, what the heck am I doing wrong? I've been two LONG days at this, grrr...

Protected Sub btnUploadFile2_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim myFtpWebRequest As FtpWebRequest
    Dim myFtpWebResponse As FtpWebResponse

    filename = Path.GetFileName(FileUpload1.FileName)

    myFtpWebRequest = CType(WebRequest.Create(ftpServer + ftpPath + filename), FtpWebRequest)
    myFtpWebRequest.Method = WebRequestMethods.Ftp.UploadFile
    myFtpWebRequest.UseBinary = True

    'NEW APPROACH USING THE STREAM OF THE FILE FROM THE FileUpload Control
    'CORRECT BYTE LENGTH - in sourceStream.BaseStream
    Dim sourceStream As New StreamReader(FileUpload1.FileContent)
    'WRONG BYTE LENGTH - in sourceStream.ReadToEnd()
    Dim fileContents As Byte() = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd())
    sourceStream.Close()
    myFtpWebRequest.ContentLength = fileContents.Length

    Dim requestStream As Stream = myFtpWebRequest.GetRequestStream()
    requestStream.Write(fileContents, 0, fileContents.Length)
    requestStream.Close()

    myFtpWebResponse = CType(myFtpWebRequest.GetResponse(), FtpWebResponse)
    myFtpWebResponse.Close()
End Sub

Thanks ever so much to Adam Maras for the amazing answer. I'll leave my blunders here for others to benefit who find this thread ;)


Solution

  • First of all, you must upload through the web server if you're going to use ASP.NET like this. Without installing a plugin on the client's browser or using an ActiveX control (or similar) you absolutely cannot upload directly from the client machine to the FTP server.

    I assume you're uploading binary files; if that's the case, the way you're using StreamReaders and StreamWriters could be corrupting the binary contents of the file. Instead, we can use the Stream.CopyTo method to move the data verbatim from one stream to the other.

    I've modified your method to use this pattern instead:

    Protected Sub btnUploadFile2_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim myFtpWebRequest As FtpWebRequest
        Dim myFtpWebResponse As FtpWebResponse
    
        filename = Path.GetFileName(FileUpload1.FileName)
    
        myFtpWebRequest = CType(WebRequest.Create(ftpServer + ftpPath + filename), FtpWebRequest)
        myFtpWebRequest.Method = WebRequestMethods.Ftp.UploadFile
        myFtpWebRequest.UseBinary = True
    
        Dim myFileStream As Stream = FileUpload1.FileContent
        myFtpWebRequest.ContentLength = myFileStream.Length
    
        Dim requestStream As Stream = myFtpWebRequest.GetRequestStream()
        myFileStream.CopyTo(requestStream)
        requestStream.Close()
    
        myFtpWebResponse = CType(myFtpWebRequest.GetResponse(), FtpWebResponse)
        myFtpWebResponse.Close()
    End Sub