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
3 files changed
tree: 04ddb55c10c91c66ac01412668a0aa931c397649
  1. tests/