May 26, 2018
Subclass of LWP::UserAgent that protects you from harm
LWPxParanoidAgent is a class subclassing LWPUserAgent, but paranoid against attackers. It’s to be used when you’re fetching a remote resource on behalf of a possibly malicious user.
This class can do whatever LWPUserAgent can callbacks, uploads from files, etc, except proxy support is explicitly removed, because in that case you should do your paranoia at your proxy.
Also, the schemes are limited to http and https, which are mapped to LWPxProtocolhttp_paranoid and LWPxProtocolhttps_paranoid, respectively, which are forked versions of the same ones without the “_paranoid”. Subclassing them didn’t look possible, as they were essentially just one huge function.
This class protects you from connecting to internal IP ranges unless you whitelist them, hostnames/IPs that you blacklist, remote webserver tarpitting your process the timeout parameter is changed to be a global timeout over the entire process, and all combinations of redirects and DNS tricks to otherwise tarpit and/or connect to internal resources.