Hide downloaded filename

relaytest49 · June 23rd, 2006, 03:29 PM

Our company posts PDF files on our server for clients. We would like to restrict access to the files to clients, but if an individual knows the URL for the file they can download it. We use long, randomly generated filenames already. We would like to hide the real filename or generate a temporary name at time of request to prevent users from saving the path to the file in favorites or using history to retrieve the file.

rrmarriott · June 24th, 2006, 04:05 AM

Hi There,

The a strategy you could take would be to load the file from the file system into a stream, and then BinaryWrite the file to the browser giving it a different filename. This would involve making a separate web form to which you would pass a the filename and probably a date/time to ensure the link can only be used once in say, 1 minute or so. This web form would then perform the BinaryWrite for you, presenting the file to the user.

The code to present the file to the user would be along the lines of the below. (No need to reinvent the wheel, this code is from http://www.eggheadcafe.com/articles/20011006.asp)

Code:

FileStream MyFileStream = new FileStream(@"d:\inetpub\wwwroot\small.pdf", FileMode.Open);
long FileSize;
FileSize = MyFileStream.Length;
byte[] Buffer = new byte[(int)FileSize];
MyFileStream.Read(Buffer, 0, (int)MyFileStream.Length);
MyFileStream.Close();
Response.ContentType="application/pdf";
Response.AddHeader( "content-disposition","attachment; filename=MyPDF.PDF");
Response.BinaryWrite(Buffer);

Notice the "filename=" in the header added to the Response.
This would be where you present your altered filename.

Hope this helps,
Rich