How can I write a caching HTTP proxy in Perl?

Question

I intend to write a simple HTTP proxy in Perl using the HTTP::Proxy module. I'm clear with the very basic task of how to create a proxy and basic filters and stuff. But what I cannot understand is how to manually force-serve a file through cache.

Basically, the scenario is this that I run this proxy in computer A. The user on computer B accesses web uses this proxy. Now, this proxy will just act as a pass through for all B's requests, until he requests a particular URL (a file, say http://abc.com/file.zip). I need to intercept this request, and instead of allowing him to download the actual file.zip, give him an already downloaded file that I manually kept on computer A.

Also, note that I might not have a web server running on computer A, so I can't just redirect the url, I need to serve it from cache.

Any pointers for this would be appreciated. Thanks

Edit: Some more info. I started using HTTP::Daemon and LWP::UserAgent in combination instead of HTTP::Proxy So far, I intercept all requests successfully, and then I search the headers for the url. If the particular filename is not there, I just pass the request to actual destination using LWP:UserAgent (simple_request) and return the response to original sender using send_response. If I find the filename, I don't further forward the request, instead I'm trying to serve my particular file using "send_file_response" method. The problem is that all other requests are working fine and comp B is able to surf the net, but when it tries to download this file, it just keeps waiting for a response. About using squid, It is not an option for me to install squid on these machines.

Answer 1

I think from the distance, we can only guess as to while the send_file_response is not working. I'd recommend

• read and understand the documentation for the modules and methods you are using

• log the action somehow in the proxy server (start, end)

• trace the communication between client B and proxy server.

Answer 2

Wouldn't it be better to just use Squid for something like this?