Call netd to update the tcp buffer size

The system server is controlling the tcp buffer now by writing to
/sys/kernel/ipv4/tcp_{rmem,wmem}_{min,def,max}. Those files are
basically the same as /proc/sys/net/ipv4/tcp_{rmem,wmem} except those
latter ones contain all three values in one file. Netd can directly write
to those files so we no longer need to depend on these android specific
files.

Test: netd_integration_test
Bug: 118572798
Change-Id: I588b48be29ecf61fd5bbf94f97f63738be4eae25

services/core/java/com/android/server/ConnectivityService.java

@@ -274,7 +274,8 @@ public class ConnectivityService extends IConnectivityManager.Stub
     private int mDefaultInetConditionPublished = 0;
 
     private INetworkManagementService mNMS;
-    private INetd mNetd;
+    @VisibleForTesting
+    protected INetd mNetd;
     private INetworkStatsService mStatsService;
     private INetworkPolicyManager mPolicyManager;
     private NetworkPolicyManagerInternal mPolicyManagerInternal;
@@ -2064,7 +2065,8 @@ public class ConnectivityService extends IConnectivityManager.Stub
         }
     }
 
-    private static final String DEFAULT_TCP_BUFFER_SIZES = "4096,87380,110208,4096,16384,110208";
+    @VisibleForTesting
+    protected static final String DEFAULT_TCP_BUFFER_SIZES = "4096,87380,110208,4096,16384,110208";
     private static final String DEFAULT_TCP_RWND_KEY = "net.tcp.default_init_rwnd";
 
     // Overridden for testing purposes to avoid writing to SystemProperties.
@@ -2095,15 +2097,11 @@ public class ConnectivityService extends IConnectivityManager.Stub
         try {
             if (VDBG || DDBG) Slog.d(TAG, "Setting tx/rx TCP buffers to " + tcpBufferSizes);
 
-            final String prefix = "/sys/kernel/ipv4/tcp_";
+            String rmemValues = String.join(" ", values[0], values[1], values[2]);
-            FileUtils.stringToFile(prefix + "rmem_min", values[0]);
+            String wmemValues = String.join(" ", values[3], values[4], values[5]);
-            FileUtils.stringToFile(prefix + "rmem_def", values[1]);
+            mNetd.setTcpRWmemorySize(rmemValues, wmemValues);
-            FileUtils.stringToFile(prefix + "rmem_max", values[2]);
-            FileUtils.stringToFile(prefix + "wmem_min", values[3]);
-            FileUtils.stringToFile(prefix + "wmem_def", values[4]);
-            FileUtils.stringToFile(prefix + "wmem_max", values[5]);
             mCurrentTcpBufferSizes = tcpBufferSizes;
-        } catch (IOException e) {
+        } catch (RemoteException | ServiceSpecificException e) {
             loge("Can't set TCP buffer sizes:" + e);
         }
 

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

@@ -96,6 +96,7 @@ import android.net.ConnectivityManager.PacketKeepalive;
 import android.net.ConnectivityManager.PacketKeepaliveCallback;
 import android.net.ConnectivityManager.TooManyRequestsException;
 import android.net.ConnectivityThread;
+import android.net.INetd;
 import android.net.INetworkPolicyListener;
 import android.net.INetworkPolicyManager;
 import android.net.INetworkStatsService;
@@ -228,6 +229,7 @@ public class ConnectivityServiceTest {
     @Mock INetworkManagementService mNetworkManagementService;
     @Mock INetworkStatsService mStatsService;
     @Mock INetworkPolicyManager mNpm;
+    @Mock INetd mMockNetd;
 
     private ArgumentCaptor<String[]> mStringArrayCaptor = ArgumentCaptor.forClass(String[].class);
 
@@ -926,8 +928,9 @@ public class ConnectivityServiceTest {
 
         public WrappedConnectivityService(Context context, INetworkManagementService netManager,
                 INetworkStatsService statsService, INetworkPolicyManager policyManager,
-                IpConnectivityLog log) {
+                IpConnectivityLog log, INetd netd) {
             super(context, netManager, statsService, policyManager, log);
+            mNetd = netd;
             mLingerDelayMs = TEST_LINGER_DELAY_MS;
         }
 
@@ -1087,7 +1090,8 @@ public class ConnectivityServiceTest {
                 mNetworkManagementService,
                 mStatsService,
                 mNpm,
-                mock(IpConnectivityLog.class));
+                mock(IpConnectivityLog.class),
+                mMockNetd);
 
         final ArgumentCaptor<INetworkPolicyListener> policyListenerCaptor =
                 ArgumentCaptor.forClass(INetworkPolicyListener.class);
@@ -4766,4 +4770,30 @@ public class ConnectivityServiceTest {
         // Clean up
         mCm.unregisterNetworkCallback(networkCallback);
     }
+
+    private static final String TEST_TCP_BUFFER_SIZES = "1,2,3,4,5,6";
+
+    private void verifyTcpBufferSizeChange(String tcpBufferSizes) throws Exception {
+        String[] values = tcpBufferSizes.split(",");
+        String rmemValues = String.join(" ", values[0], values[1], values[2]);
+        String wmemValues = String.join(" ", values[3], values[4], values[5]);
+        waitForIdle();
+        verify(mMockNetd, atLeastOnce()).setTcpRWmemorySize(rmemValues, wmemValues);
+        reset(mMockNetd);
+    }
+
+    @Test
+    public void testTcpBufferReset() throws Exception {
+        mCellNetworkAgent = new MockNetworkAgent(TRANSPORT_CELLULAR);
+        reset(mMockNetd);
+        // Simple connection should have updated tcp buffer size.
+        mCellNetworkAgent.connect(false);
+        verifyTcpBufferSizeChange(ConnectivityService.DEFAULT_TCP_BUFFER_SIZES);
+
+        // Change link Properties should have updated tcp buffer size.
+        LinkProperties lp = new LinkProperties();
+        lp.setTcpBufferSizes(TEST_TCP_BUFFER_SIZES);
+        mCellNetworkAgent.sendLinkProperties(lp);
+        verifyTcpBufferSizeChange(TEST_TCP_BUFFER_SIZES);
+    }
 }