The parsing in TRR::DohDecode is getting rather complicated.
Moreover, it would be nice to be able to reuse this code in the future, if we ever want to have a HTTPSVC implementation that works without TRR.

https://phabricator.services.mozilla.com/D71389#inline-430024

We should probably factor out parsing. I think we should have mResponse be a type that can parse itself.

(In reply to Dragana Damjanovic [:dragana] from bug 1641222 comment #2)

A general question that can be a follow up: I think we should structure trr a bit more. As an example what about trr request returns a response and does not follow CNAME or AliasForm.. And we have another layer that decides if it return a result (in case of A/AAAA ) answer or if it creates a new trr query. Basically to split TRR.cpp into 2 classes a simple request/response and a "recursive resolver"