onion-tunnel: Add TCP test coverage to parser
This commit adds almost full test coverage to the TCP related aspects of the parser, even including the IPv6 hop-by-hop feature.
It also tests various edge cases, including but not limited to malformed TCP and IP packets.
Finally, it also modifies the general return type of the parser to return a Result<>
instead of an Option<>
, which allows a more fine grained testing approach.
Based on: !291 (merged) See: #111
Edited by Clara Engler