commit 6a3ba4f7a4b7c610f05529ffb3f8a7c6f3c0c568
author Maciej Żenczykowski <maze@google.com> Sat Sep 30 21:06:33 2023 +0000
committer Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> Sat Sep 30 21:06:33 2023 +0000
tree df4067cb836e9128c7e521afd52ee75d391ca25c
parent 761c9f17c5dfe54c70ead91b7b71908081dfd86c
parent 5d4d419b970780962007eb9d810e2dabcf48cfd8

Lower CLAT max MTU from 65536 to 1528. am: 9f94648b7f am: 5d4d419b97

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2677095

Change-Id: Ic1fac02898c47222e843c44e1b4b9c928ae97dd3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

service/src/com/android/server/connectivity/ClatCoordinator.java

diff --git a/service/src/com/android/server/connectivity/ClatCoordinator.java b/service/src/com/android/server/connectivity/ClatCoordinator.java
index eb3e7ce..17de146 100644
--- a/service/src/com/android/server/connectivity/ClatCoordinator.java
+++ b/service/src/com/android/server/connectivity/ClatCoordinator.java
@@ -78,7 +78,7 @@
     @VisibleForTesting
     static final int MTU_DELTA = 28;
     @VisibleForTesting
-    static final int CLAT_MAX_MTU = 65536;
+    static final int CLAT_MAX_MTU = 1500 + MTU_DELTA;
 
     // This must match the interface prefix in clatd.c.
     private static final String CLAT_PREFIX = "v4-";
@@ -673,7 +673,7 @@
             throw new IOException("Detect MTU on " + tunIface + " failed: " + e);
         }
         final int mtu = adjustMtu(detectedMtu);
-        Log.i(TAG, "ipv4 mtu is " + mtu);
+        Log.i(TAG, "detected ipv4 mtu of " + detectedMtu + " adjusted to " + mtu);
 
         // Config tun interface mtu, address and bring up.
         try {

tests/unit/java/com/android/server/connectivity/ClatCoordinatorTest.java

diff --git a/tests/unit/java/com/android/server/connectivity/ClatCoordinatorTest.java b/tests/unit/java/com/android/server/connectivity/ClatCoordinatorTest.java
index 4158663..88044be 100644
--- a/tests/unit/java/com/android/server/connectivity/ClatCoordinatorTest.java
+++ b/tests/unit/java/com/android/server/connectivity/ClatCoordinatorTest.java
@@ -508,10 +508,10 @@
         // Expected mtu is that the detected mtu minus MTU_DELTA(28).
         assertEquals(1372, ClatCoordinator.adjustMtu(1400));
         assertEquals(1472, ClatCoordinator.adjustMtu(ETHER_MTU));
-        assertEquals(65508, ClatCoordinator.adjustMtu(CLAT_MAX_MTU));
+        assertEquals(1500, ClatCoordinator.adjustMtu(CLAT_MAX_MTU));
 
-        // Expected mtu is that CLAT_MAX_MTU(65536) minus MTU_DELTA(28).
-        assertEquals(65508, ClatCoordinator.adjustMtu(CLAT_MAX_MTU + 1 /* over maximum mtu */));
+        // Expected mtu is that CLAT_MAX_MTU(1528) minus MTU_DELTA(28).
+        assertEquals(1500, ClatCoordinator.adjustMtu(CLAT_MAX_MTU + 1 /* over maximum mtu */));
     }
 
     private void verifyDump(final ClatCoordinator coordinator, boolean clatStarted) {