How to add field to connection info from tls_clienthello

[terryltoms]

I wrote an addon that implements tls_clienthello. The addon calculate a something over the client hello, and I want to show this on the request (connection tab, marker, etc...). How do I do this from the hook?

[Ilke-dev]

Hi i think i have a solution for you. The ClientHelloData class is actually also accessible from the HTTPFlow class as a client connection.

Checkout this attribute of ClientHelloData: https://github.com/mitmproxy/mitmproxy/blob/main/mitmproxy/tls.py#L120

Then checkout this attribute of Flow: https://github.com/mitmproxy/mitmproxy/blob/main/mitmproxy/flow.py#L56

I think you can access the ClientHelloData from the Flow class as well.

(FYI Flow class is inherited by HTTPFlow that is passed along the hook: https://github.com/mitmproxy/mitmproxy/blob/main/mitmproxy/http.py#L1230)

[terryltoms]

I think it wouldn't work.
clientHelloData -> context -> client
flow -> client
Both hold client, but we cannot get to client hello data from flow. I tried to save a field there, but it is very hacky and didn't work

[mhils]

The current workaround to do this is to define a client_conn -> x WeakKeyDictionary. You can see this in action in the ProxyAuth addon. We should maybe add something like client_conn.metadata at some point, let's see. :)