Talk:How Mozilla determines MIME Types

From MDC

Hello, I'm sorry that I may be annoying you, but you are probably among the best few persons who can effectively answer my query! I got you address on http://developer.mozilla.org/en/docs/How_Mozilla_determines_MIME_Types

I maintain a website, and it happened to me twice that a mp3 file was upload from Firefox with an invalid MIME-Type supplied.

The first time, using: Mozilla/5.0 (Windows; U; Windows NT 5.1; fr; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3 And the MIME type supplied by the browser was "application/force-download"

The second time: Mozilla/5.0 (Windows; U; Windows NT 5.1; fr; rv:1.8.0.11) Gecko/20070312 Firefox/1.5.0.11 Sent MIME type "application/mp3"

Both mp3 appeared to be valid audio/mp3 files, and both methods of content-sniffing and extension-sniffing on server-side returned audio/mp3

All I can see is that these erroneous MIME Types were probably given by another host from where the file had been downloaded, and it sticked to the file until it has been uploaded, probably within the same session (execution) of Firefox, to our website.

Can you confirm, or infirm my hypothesis? Does Firefox store the MIME types of the downloaded files? If yes, when and where does it happen? My main concern is to avoid the proliferation of erroneous mime types, and to develop an effective approach to control them. A better understanding of how can this happen will definitely help.

--Biguenique 01:21, 22 May 2007 (PDT)