Make an HTTP requestor Firefox extension for meek-client
Following the discussion at https://lists.torproject.org/pipermail/tor-dev/2014-February/006266.html and the summary at [[doc/meek#HowtolooklikebrowserHTTPS]], I think our best option for having TLS that looks like a browser is to make a browser extension that meek-client uses as a tool to make HTTPS requests.
To summarize: meek-client needs to make HTTPS requests, but needs to do so with a TLS signature that isn't trivially blockable. A browser doesn't have a blockable TLS signature, so we can have meek-client drive a browser to make requests on its behalf. Rather than ship an entire separate browser to users, we can use an extension in Tor Browser itself, one whose only purpose is to make HTTPS requests using the browser's networking code, bypassing the browser's proxy settings that would otherwise send all requests through Tor.
The communication goes:
There will need to be some kind of IPC between meek-client and the extension. I haven't figured out how that will work. Maybe the extension can be an HTTP proxy--that would be super easy to integrate with meek-client. But maybe you don't want an HTTP proxy running in your browser bundle, even if it's only intended for a specific purpose. Maybe the IPC needs to be authenticated somehow, and the extension needs to somehow inform the other process of how to contact it.