Add TunUtils as utility to reflect packets

This patch adds a TunUtils class, allowing for packet capture over a TUN
interface, inspection of some basic header fields, and reflection of
packets with flipped src/dst headers.

Bug: 72950854
Test: Ran, passing
Change-Id: I9fdba4a905886c7a4820d86ef52c0cc1843215b2
Merged-In: I9fdba4a905886c7a4820d86ef52c0cc1843215b2
(cherry picked from commit 2f07cd8551d755a4076e94b9e620bc446a66bf54)
3 files changed
tree: 0119c7fb16cbd8d2903857c4656c0d440c0f095e
  1. tests/