It's dumb that this needs to be two different options, but optparse doesn't
support optional arguments. It would be much nicer to just have "-c" for "all",
and "-c filter" for a specified filter.
Also add the --rheader command-line option to mitmdump to let the user specify
an arbitrary number of significant headers. The default is to treat no headers
as significant.
If this option is passed all requests that are not part of a replayed
conversation are killed. If the option is not passed, such requests are passed
through to the server as usual.
This is a big patch removing the assumption that there's one connection per
Request/Response pair. It touches pretty much every part of mitmproxy, so
expect glitches until everything is ironed out.
