Allow download of filenames with &'s in them

I want to allow users to download files that have names containing & characters.

We've escaped our way through the problem but cannot seem to get around one last obstacle.

Here in Download.asp.vb we have

Code:

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Imports System.IO

Partial Class Clients_Download
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim ctx As HttpContext = HttpContext.Current
        Dim response As HttpResponse = ctx.Response
        Dim sFile As String = Request.QueryString("filename".ToString)

        ' Buffer to read 10K bytes in chunk:
        Dim buffer(10000) As Byte
        ' Length of the file:
        Dim length As Integer
        ' Total bytes to read:
        Dim dataToRead As Long
        ' Identify the file to download including its path.
        Dim filepath As String = sFile
        ' Identify the file name.
        Dim filename As String = System.IO.Path.GetFileName(filepath)

        Using iStream As New FileStream(filepath, System.IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.Read)
            ' Total bytes to read:
            dataToRead = iStream.Length

            response.ContentType = "application/octet-stream"
            response.AddHeader("Content-Disposition", "attachment; filename=" & filename)

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And here is where it fails - the attachment; filename= line.

The filename vbl has the & character within it.

The pop-up that appears in the browser window asking for where to save the file shows a filename WITHOUT the &'s.

Here is the continuation of the code

Code:

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            ' Read the bytes.
            While dataToRead > 0
                ' Verify that the client is connected.
                If response.IsClientConnected Then
                    ' Read the data in buffer
                    length = iStream.Read(buffer, 0, 10000)

                    ' Write the data to the current output stream.
                    response.OutputStream.Write(buffer, 0, length)

                    ' Flush the data to the HTML output.
                    response.Flush()

                    ReDim buffer(10000) ' Clear the buffer
                    dataToRead = dataToRead - length
                Else
                    'prevent infinite loop if user disconnects
                    dataToRead = -1
                End If
            End While

            iStream.Close()

            'delete the file after downloading it
            If Request.QueryString("delfile") = "true" Then
                'make sure it contains \temp\ dir
                If sFile.Contains("\temp\") Then
                    File.Delete(sFile)
                End If
            End If
            response.End()
        End Using
    End Sub

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It works ok for me.

I assume this is a typo,
Dim sFile As String = Request.QueryString("filename".ToString)
and should be changed to:
Dim sFile As String = Request.QueryString("filename").ToString


This is what I get, running your code as it is.

In the first box, filename is in a label, so it assumes & as shortcut and shows as underscore. But in the actual box where I specify filename to save, I can see the "&" in filename.

Attachment 78701

Attachment 78702

Hey,

You can try your luck with HttpServerUtility.HtmlEncode Method. This will convert characters to their respective HTML Hex format.

BTW how big are your files? Why do you need to read/write in chunks?

This code is a simple one-liner and has always worked for me:

vb.net Code:

Sub TransmitFile(ByVal fileName As String)
    Response.ContentType = "application/octet-stream"
    Response.AddHeader("Content-Disposition", "attachment; filename=""" & System.IO.Path.GetFileName(fileName) & """")
    Try
        Response.TransmitFile(fileName)
    Catch ex As Exception
        Response.Write(ex.ToString)
    End Try
End Sub
 
Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim fileName As String = "C:\Temp\abc&d.txt"
    TransmitFile(fileName)
End Sub

I'd suggest the URLEncode instead... otherwise you'll get& in the file name. By URLEncoding it, you get the %XX where XX is the ascii code (for instance a space comes out as %20). the browser & client should be able to sort it out from there.

-tg

@pradeep - I see the initial pop up has the D underlined - which is what a
& character would do to a string - that stinks.

but you are seeing the & character in the actual filename.

What version of IE

Quote:

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Originally Posted by Pradeep1210

BTW how big are your files? Why do you need to read/write in chunks?

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They are huge - we do multi GB uploads and downloads

Quote:

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Originally Posted by szlamany

@pradeep - I see the initial pop up has the D underlined - which is what a
& character would do to a string - that stinks.

but you are seeing the & character in the actual filename.

What version of IE

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IE Version is: 6.0 :o

Yep. That underscore appearing there looks like a bug to me. Maybe it has been fixed in the latter versions of IE, but I'm not sure. I never use it other than development work.

Attachment 78703

Quote:

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Originally Posted by szlamany

They are huge - we do multi GB uploads and downloads

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OK. Then it makes a lot of sense to transfer file in chunks, otherwise just a handful of users can eat up all the server memory and maybe crash your server too. :)

Quote:

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Originally Posted by Pradeep1210

OK. Then it makes a lot of sense to transfer file in chunks, otherwise just a handful of users can eat up all the server memory and maybe crash your server too. :)

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Which is exactly what was happening!