Can I web-serve a document from one place and its content-type from another?

Question

Hi,

I am trying to write a web application that will serve uploaded files, and let the uploader specify the content type. For this to work, I need to be able to control the content-type when I serve the file. With most web-servers I'm aware of (e.g. Apache), the best I can do in that respect is set an appropriate suffix and hope that nobody uploads a file with an "unsupported" content-type. What I would like to do instead is set the content-type in my code processing the request -- e.g. have a database record describing the file and pull it from there. But then, it seems I would need to serve the whole file from my application, as if it were dynamic, and pay a severe performance penalty (among other things, losing the ability to serve it directly from CDNs such as Amazon S3).

So the question is --

1. Is there a way for me to tell a web browser "Take the file from that URL, but use the content-type supplied in the redirect response"?

2. Is there a less-optimal solution, which would still allow me to use a static-content-server for the file while using a dynamic application for the content-type?

Thanks, Shai.

Answer 1

Yes. You can write an Apache module (in your language of choice, including C, Perl, Python, etc.) that filters a request by replacing the content-type header with one fetched from your data store. For example, using mod_python, you can create a PythonTypeHandler that does exactly what you describe, but lets Apache do the heavy lifting of serving the static content.

Answer 2

You might also want to look into mod_mime_magic to take care of this. It will peek into the file to determine what type it is.

http://httpd.apache.org/docs/2.2/mod/mod%5Fmime%5Fmagic.html

Also, on the upload side you could check that the file extension matches the actual file type using whatever magic module is available for your preferred language.