The condition for deleting IPv4 forwarding rules.
1. When the tethering client has gone, deletes the client and its
rules.
2. When the upstream has gone, deletes all rules.
3. When the upstream has changed, deletes all rules.
Test: atest TetheringCoverageTests and check IPv4 offload rules
via dumpsys tethering in the following test cases.
Bug: 190783768
Test cases:
a. Loss upstream interface while tethering
1. Enable WIFI tethering
2. Disable upstream interface
3. Check the rules are removed.
b. Loss downstream interfaces while tethering
1. Enable WIFI tethering
2. Enable BT tethering
3. Disable BT tethering
4. Check the BT tether rules are removed.
5. Disable WIFI tethering
6. Check the WIFI tether rules are removed.
c. Switch upstream interface while tethering
1. Enable WIFI tethering
2. Enable BT tethering
3. Switch upstream interface from cellular to wifi.
4. Check all rules are removed.
d. Enable NAT failure (manual)
Log:
The rule deletion in each case.
- IpServer#stopIPv4: case b and case d.
- BpfCoordinator#updateUpstreamNetworkState: case a and case c.
Test case a
06-23 09:58:59.245 [...] Tethering: [BpfCoordinator]
updateUpstreamNetworkState tetherOffloadRule4Clear wlan2
Test case b
06-07 22:17:51.886 [..] Tethering: [bt-pan] cleanupUpstream bt-pan
06-07 22:17:51.888 [..] Tethering: [bt-pan] stopIPv4 bt-pan
06-07 22:18:23.769 [..] Tethering: [wlan2] cleanupUpstream wlan2
06-07 22:18:23.772 [..] Tethering: [wlan2] stopIPv4 wlan2
Test case c
06-08 11:11:48.277 [..] Tethering: [BpfCoordinator]
updateUpstreamNetworkState tetherOffloadRule4Clear bt-pan
06-08 11:11:48.396 [..] Tethering: [BpfCoordinator]
updateUpstreamNetworkState tetherOffloadRule4Clear wlan2
06-08 11:11:48.579 [..] Tethering: [wlan2] cleanupUpstreamInterface
wlan2
06-08 11:11:48.808 [..] Tethering: [bt-pan] cleanupUpstreamInterface
bt-pan
Enabling NAT failure
06-08 13:04:18.117 [..] Tethering: [wlan2] Exception enabling NAT [..]
06-08 13:04:18.234 [..] Tethering: [wlan2] cleanupUpstream wlan2
06-08 13:04:18.246 [..] Tethering: [wlan2] stopIPv4 wlan2
Change-Id: Id505a3deb277bbe0f44403234d8ca8bbf01eec80
a6e7869646