commit 6eacfb6b733e1d4dee3db3438f81c42d944d88f8
author Mark Chien <markchien@google.com> Wed Oct 07 09:55:32 2020 +0000
committer Mark Chien <markchien@google.com> Thu Oct 08 00:21:26 2020 +0000
tree c0420833486d060be1569143eab7e4cc2f30c157
parent 67c7a7868cbe45dd1f8a24f7b1c08d6c4f7af5c7

Make the IP subnet persistent till reboot

Make the IP subnet persistent if it do not conflict with upstream.
It allow client to reuse its IP that usually reduce DHCP procedure.

Bug: 168169687
Test: atest TetheringTests
Change-Id: Iddc5304730dce7b11c5d124b7eddce057d752bbd

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1432958

Change-Id: I60ed54651034f21ca1cd253d272ac3478881b4e0
Merged-In: Iddc5304730dce7b11c5d124b7eddce057d752bbd
(cherry picked from commit 177e2d8d1867d7e72d00c81d6fbbed756c9f0568)

Tethering/src/android/net/ip/IpServer.java

diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index 673cbf0..66f216b 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -605,7 +605,7 @@
         if (VDBG) Log.d(TAG, "configureIPv4(" + enabled + ")");
 
         if (enabled) {
-            mIpv4Address = requestIpv4Address();
+            mIpv4Address = requestIpv4Address(true /* useLastAddress */);
         }
 
         if (mIpv4Address == null) {
@@ -650,14 +650,14 @@
         return configureDhcp(enabled, mIpv4Address, mStaticIpv4ClientAddr);
     }
 
-    private LinkAddress requestIpv4Address() {
+    private LinkAddress requestIpv4Address(final boolean useLastAddress) {
         if (mStaticIpv4ServerAddr != null) return mStaticIpv4ServerAddr;
 
         if (mInterfaceType == TetheringManager.TETHERING_BLUETOOTH) {
             return new LinkAddress(BLUETOOTH_IFACE_ADDR);
         }
 
-        return mPrivateAddressCoordinator.requestDownstreamAddress(this);
+        return mPrivateAddressCoordinator.requestDownstreamAddress(this, useLastAddress);
     }
 
     private boolean startIPv6() {
@@ -928,7 +928,7 @@
         }
 
         final LinkAddress deprecatedLinkAddress = mIpv4Address;
-        mIpv4Address = requestIpv4Address();
+        mIpv4Address = requestIpv4Address(false);
         if (mIpv4Address == null) {
             mLog.e("Fail to request a new downstream prefix");
             return;