commit 04252031522382efb7bb56566898a69ea25739da
author Hansen Kurli <hkurli@google.com> Wed Dec 07 11:21:49 2022 +0000
committer Hansen Kurli <hkurli@google.com> Tue Dec 20 09:28:36 2022 +0000
tree d4048abf7273fdfc33a7bd08b2ec1471a96adc82
parent edbf34a18270262c20360e43be346d9bcd9d1379

Ensure MTU is set for new interfaces.

Setting the MTU for an interface should not be skipped when the
interface names are different. This occurs when a VPN network creates
a new interface with identical MTU.

Bug: 246398088
Test: atest ConnectivityServiceTest
Test: Manual test: Connect to VPN network and switch networks
Test: Confirm MTU of interface is set correctly with `adb shell ip addr`
Change-Id: I811a01feca2fb2130c57c6c924145314180434c5

service/src/com/android/server/ConnectivityService.java

diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index a44494c..80ec8ae 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -3116,22 +3116,23 @@
     private void updateMtu(@NonNull LinkProperties newLp, @Nullable LinkProperties oldLp) {
         final String iface = newLp.getInterfaceName();
         final int mtu = newLp.getMtu();
-        if (oldLp == null && mtu == 0) {
+        if (mtu == 0) {
             // Silently ignore unset MTU value.
             return;
         }
-        if (oldLp != null && newLp.isIdenticalMtu(oldLp)) {
-            if (VDBG) log("identical MTU - not setting");
+        if (oldLp != null && newLp.isIdenticalMtu(oldLp)
+                && TextUtils.equals(oldLp.getInterfaceName(), iface)) {
+            if (VDBG) log("identical MTU and iface - not setting");
             return;
         }
-        if (!LinkProperties.isValidMtu(mtu, newLp.hasGlobalIpv6Address())) {
-            if (mtu != 0) loge("Unexpected mtu value: " + mtu + ", " + iface);
+        // Cannot set MTU without interface name
+        if (TextUtils.isEmpty(iface)) {
+            if (VDBG) log("Setting MTU size with null iface.");
             return;
         }
 
-        // Cannot set MTU without interface name
-        if (TextUtils.isEmpty(iface)) {
-            loge("Setting MTU size with null iface.");
+        if (!LinkProperties.isValidMtu(mtu, newLp.hasGlobalIpv6Address())) {
+            loge("Unexpected mtu value: " + mtu + ", " + iface);
             return;
         }
 

tests/unit/java/com/android/server/ConnectivityServiceTest.java

diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index 16f7039..3d6ee09 100755
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -17155,7 +17155,6 @@
         mWiFiNetworkAgent.sendLinkProperties(new LinkProperties(lp2));
 
         waitForIdle();
-        // TODO(b/246398088): the MTU should be set on the new interface.
-        verify(mMockNetd, never()).interfaceSetMtu(eq(ifaceName2), eq(mtu));
+        verify(mMockNetd).interfaceSetMtu(eq(ifaceName2), eq(mtu));
     }
 }