Forcing download in IE5.5 (PC) or IE Mac

Anon

This method of forcing a download

header("Content-type: application/octet-stream; name=\"$fn\"");
header("Content-Disposition: attachment; filename=\"$fn\"");
header("Content-Transfer-Encoding: binary");

passthru("cat \"$fn\"");

Works fine for Netscape 4.x (any platform)
and IE 5.0 on the PC.

It doesn't work for IE5.5 on the PC. It
always downloads the html source that originated the download. I tried a slight
adjustment that someone mentioned using:

header("Content-Disposition: filename=\"$fn\"");

but this has unpredictable results depending on whether IE knows what to do with the file. It seems that the suffix of "$fn" overrides any mime type passed in the Content-Type header.

I can get nothing to work reliably under Explorer on the MAC.

Anyone out there have any ideas or coroborating experience?

Neil

Anon

Yes, I had a "corroborating experience". IE is a big horror (to stay polite). It doesn't respect the HTTP norm and absolutely tries to guess the file format. Even if the mime-type is application/octet-stream ! It sounds crazy, but for Microsoft, this mime-type is "ambiguous"; the browser examines the beginning of the file to find out the format (they call it "datasniffing"). The trick is to give it an unknown mime-type, such as application/unknown, which is not considered as ambiguous ! BUT (there's a but...), if you give it a filename with Content-Disposition, it will guess the format from the extension. So there's no solution if you want to download a file and suggest a correct filename if the extension is known from IE. All you can do is give a false extension and let the user correct by himself.
For an application I recently made, I wanted to download a report in HTML format. I did the following :

test the browser
if it's not IE, set the mime-type to application/octet-stream and give report.htm filename
if it's IE, set the mime-type to application/unknown and give no filename. So the default was report.php3

By luck, most people of the company were using Netscape...

2 interesting URLs about this issue :

http://ppewww.ph.gla.ac.uk/~flavell/www/content-type.html
http://msdn.microsoft.com/workshop/networking/moniker/overview/appendix_a.asp

Anon

This works on ie5.5 but not sure about MAC.

Header("Content-Disposition: attachment; filename=\"$filename\"");
Header("Content-Type: application/octet-stream");

Anon

No it doesn't. I always get the text of the html file, not the asset I'm trying to download.

Anon

Complicating things even more is that if you have the "attachment" keyword in the Content-Disposition you always get the text of the source html file instead of the actual asset you are trying to save. This, at least, seems like an outright bug.

Anon

Actually, that did work fine for me (IE 5.5).
In JSP. Email me for details.