tree 2eec80bee71023e7ce26ee5efbc02f3537402017
parent a6d6184760a14485f0a8b66df99d9ba0675e8487
author Hungming Chen <nuccachen@google.com> 1672325235 +0800
committer Hungming Chen <nuccachen@google.com> 1672760190 +0800

BpfCoordinator: publish upstream interface mtu to v4 offload rule

Respect the upstream interface mtu instead of always setting
mtu 1500.

Using upstream interface mtu is probably not the best solution
for tether offload pmtu but it at least respects the upstream
interface mtu which may be less than 1500.

Test: manual test
1. Connect to carrier Taiwan Star.
2. Enable tethering and check the mtu 1434 in dumpsys.
IPv4 Upstream: proto [inDstMac] iif(iface) src -> nat ->
dst [outDstMac] pmtu age
  udp [02:10:45:32:ef:35] 54(54) 192.168.72.125:39034
  -> 15(rmnet1) 100.83.189.11:39034
  -> 142.251.43.14:443 [00:00:00:00:00:00] 1434 69657ms
IPv4 Downstream: proto [inDstMac] iif(iface) src -> nat
  -> dst [outDstMac] pmtu age
  udp [00:00:00:00:00:00] 15(rmnet1) 142.251.43.14:443
  -> 54(54) 100.83.189.11:39034
  -> 192.168.72.125:39034 [9a:8a:4d:ec:a4:7c] 1434 69633ms

Bug: 262860312
Test: atest BpfCoordinatorTest
Change-Id: Ic6dcb95ed76d5306053e4645b6baebc67ff082cf