Downloading File with Unicode File Name Causes Problem

Posted on 2006-11-05
Medium Priority
Last Modified: 2008-03-17
In order to track file download rates, for all the files available for download on my web page I've placed a link to an ASP page which increments the download counter. Within the same page, it reads the binary data from file and uses following code to display the prompt window so user can either choose to save or open the file.

Response.CharSet = "UTF-8"
Response.AddHeader "Content-disposition", "attachment;filename=" & stFileName

The code works fine but whenever the file name contains unicode characters, file name displayed and saved on the prompt window is not the original name, rather it displayed some alphanumeric characters.

If I use Response.Redirect to the given file name, the prompt windows gives the correct result, but I cannot prevent user browser from opening the know MIME types within the browser itself.

I would like to find out how I can solve the unicode filename problem.

Thanks in advance!
Question by:guest321
LVL 25

Expert Comment

ID: 17876724
interestign conundrum....

what happnes if you comment out this line:
Response.CharSet = "UTF-8"

also, I've found it best to stream the file to the browser using the ADO.Stream method.  This may be a better route and may cure the unciode filename issue

basically you pass the path to the file, and then specify the filename.

Here is the function, and how to use it:

Function DownloadFile( strFile, strDownloadFilename )
     Dim strFilename,objStream,objFilesystem,objFilestream
     Dim intFileLength
     strFilename = strFile
     Response.Buffer = True
     Set objStream = Server.CreateObject("ADODB.Stream")
     objStream.Type = 1
     Set objFilesystem = Server.CreateObject("Scripting.FileSystemObject")
     if not objFilesystem.FileExists(strFilename) then
          Response.Write("<h1>Error</h1>: " & strFilename & " does not exist<p>")
     end if
     Set objFilestream = objFilesystem.GetFile( strFilename )
     intFilelength = objFilestream.size
     objStream.LoadFromFile( strFilename )
     if err then
          Response.Write("<h1>Error: </h1>" & err.Description & "<p>")
     end if
     if Len( Trim(strDownloadFilename) ) > 0 then
          strDownloadFilename = Trim( strDownloadFilename )
          strDownloadFilename = objFilestream.name
     end if
     Response.AddHeader "Content-Disposition", "attachment; filename=" & strDownloadFilename
     Response.AddHeader "Content-Length", intFilelength
     Response.Charset = "UTF-8"
     for i = 0 to objStream.size
          i = i + 128000
     Set objFilestream = Nothing
End Function

to use it:
strPath = "c:\the\path\to\thefile.ext"
theFileToDownload = "thefilenameyouwanttocallit.ext"
Call downloadFile(strPath, theFileToDownload)

LVL 58

Expert Comment

ID: 17876773
I always  use..

strfileName = "someobject.pdf"

Response.ContentType = "application/octet-stream"
Response.AddHeader "content-disposition","attachment;filename=" & strfileName

Set objStream = Server.CreateObject("ADODB.Stream")
objStream.Type = 1 '1=binary 2=text
objStream.LoadFromfile Server.MapPath(strfileName)

Response.BinaryWrite objStream.Read

Set objStream = Nothing

Accepted Solution

gete earned 375 total points
ID: 17878717
RFC 2183, Section 2:

   NOTE ON PARAMETER VALUE LENGHTS: A short (length <= 78 characters)
   parameter value containing only non-`tspecials' characters SHOULD be
   represented as a single `token'.  A short parameter value containing
   only ASCII characters, but including `tspecials' characters, SHOULD
   be represented as `quoted-string'.  Parameter values longer than 78
   characters, or which contain non-ASCII characters, MUST be encoded as
   specified in [RFC 2184].

You can see the encoding spec in RFC 2231 (which obsoletes RFC 2184).

For more example about implementation, you can visit http://www.codeproject.com/aspnet/NonUSASCII.asp
(unfortunately, it's in ASP.NET/C#).

Author Comment

ID: 17887307
Thank you everyone for the help! The problem has been solved by enclosing the file name with Server.URLEncode() method (also mentioned as Encoded-word mechanism in gete's given url).
LVL 25

Expert Comment

ID: 17889158
glad we could help :|

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