HandlePacket and Inject now receive/take Packets. This is a handy
container for the packet, and the attached Trace method can be used
to print traces from custom packet handlers that integrate nicely
with natlab's internal traces.
Signed-off-by: David Anderson <danderson@tailscale.com>
The firewall provides a ProcessPacket handler, and implements an
address-and-port endpoint dependent firewall that allows all
traffic to egress from the trusted interface, and only allows
inbound traffic if corresponding outbound traffic was previously
seen.
Signed-off-by: David Anderson <danderson@tailscale.com>
