Add SkipNativeNetworkCreation flag in NetworkAgentConfig

This flag allows ConnectivityService to skip native network creation,
deferring this responsibility to Tethering. This is necessary because:

- ConnectivityService requires the NetworkAgent to be in the CONNECTED
  state to configure routing and invokes NetworkCallback#onAvailable
  once ready.
- Tethering requires lower-layer interactions to be completed before
  notifying applications.

This approach ensures proper synchronization between ConnectivityService
and Tethering during network setup.

Long-term, all netd operations should be handled by ConnectivityService
when it supports early native network creation in the CONNECTING state.

As a mid-term solution, this flag enables Tethering to manage native
network creation within the IpServer.

Test: atest ConnectivityCoverageTests:android.net.connectivity.android.net.NetworkAgentConfigTest
Bug: 349487600
Change-Id: I84da9c74dc4d40c7cd36c6657f17a158affed689

framework/src/android/net/NetworkAgentConfig.java

@@ -272,6 +272,27 @@ public final class NetworkAgentConfig implements Parcelable {
         return mVpnRequiresValidation;
     }
 
+    /**
+     * Whether the native network creation should be skipped.
+     *
+     * If set, the native network and routes should be maintained by the caller.
+     *
+     * @hide
+     */
+    private boolean mSkipNativeNetworkCreation = false;
+
+
+    /**
+     * @return Whether the native network creation should be skipped.
+     * @hide
+     */
+    // TODO: Expose API when ready.
+    // @FlaggedApi(Flags.FLAG_TETHERING_NETWORK_AGENT)
+    // @SystemApi(client = MODULE_LIBRARIES) when ready.
+    public boolean shouldSkipNativeNetworkCreation() {
+        return mSkipNativeNetworkCreation;
+    }
+
     /** @hide */
     public NetworkAgentConfig() {
     }
@@ -293,6 +314,7 @@ public final class NetworkAgentConfig implements Parcelable {
             mLegacyExtraInfo = nac.mLegacyExtraInfo;
             excludeLocalRouteVpn = nac.excludeLocalRouteVpn;
             mVpnRequiresValidation = nac.mVpnRequiresValidation;
+            mSkipNativeNetworkCreation = nac.mSkipNativeNetworkCreation;
         }
     }
 
@@ -483,6 +505,26 @@ public final class NetworkAgentConfig implements Parcelable {
             return this;
         }
 
+        /**
+         * Sets the native network creation should be skipped.
+         *
+         * @return this builder, to facilitate chaining.
+         * @hide
+         */
+        @NonNull
+        // TODO: Expose API when ready.
+        // @FlaggedApi(Flags.FLAG_TETHERING_NETWORK_AGENT)
+        // @SystemApi(client = MODULE_LIBRARIES) when ready.
+        public Builder setSkipNativeNetworkCreation(boolean skipNativeNetworkCreation) {
+            if (!SdkLevel.isAtLeastV()) {
+                // Local agents are supported starting on U on TVs and on V on everything else.
+                // Thus, only support this flag on V+.
+                throw new UnsupportedOperationException("Method is not supported");
+            }
+            mConfig.mSkipNativeNetworkCreation = skipNativeNetworkCreation;
+            return this;
+        }
+
         /**
          * Returns the constructed {@link NetworkAgentConfig} object.
          */
@@ -510,7 +552,8 @@ public final class NetworkAgentConfig implements Parcelable {
                 && Objects.equals(legacySubTypeName, that.legacySubTypeName)
                 && Objects.equals(mLegacyExtraInfo, that.mLegacyExtraInfo)
                 && excludeLocalRouteVpn == that.excludeLocalRouteVpn
-                && mVpnRequiresValidation == that.mVpnRequiresValidation;
+                && mVpnRequiresValidation == that.mVpnRequiresValidation
+                && mSkipNativeNetworkCreation == that.mSkipNativeNetworkCreation;
     }
 
     @Override
@@ -518,7 +561,8 @@ public final class NetworkAgentConfig implements Parcelable {
         return Objects.hash(allowBypass, explicitlySelected, acceptUnvalidated,
                 acceptPartialConnectivity, provisioningNotificationDisabled, subscriberId,
                 skip464xlat, legacyType, legacySubType, legacyTypeName, legacySubTypeName,
-                mLegacyExtraInfo, excludeLocalRouteVpn, mVpnRequiresValidation);
+                mLegacyExtraInfo, excludeLocalRouteVpn, mVpnRequiresValidation,
+                mSkipNativeNetworkCreation);
     }
 
     @Override
@@ -539,6 +583,7 @@ public final class NetworkAgentConfig implements Parcelable {
                 + ", legacyExtraInfo = '" + mLegacyExtraInfo + '\''
                 + ", excludeLocalRouteVpn = '" + excludeLocalRouteVpn + '\''
                 + ", vpnRequiresValidation = '" + mVpnRequiresValidation + '\''
+                + ", skipNativeNetworkCreation = '" + mSkipNativeNetworkCreation + '\''
                 + "}";
     }
 
@@ -563,33 +608,35 @@ public final class NetworkAgentConfig implements Parcelable {
         out.writeString(mLegacyExtraInfo);
         out.writeInt(excludeLocalRouteVpn ? 1 : 0);
         out.writeInt(mVpnRequiresValidation ? 1 : 0);
+        out.writeInt(mSkipNativeNetworkCreation ? 1 : 0);
     }
 
     public static final @NonNull Creator<NetworkAgentConfig> CREATOR =
             new Creator<NetworkAgentConfig>() {
-        @Override
-        public NetworkAgentConfig createFromParcel(Parcel in) {
-            NetworkAgentConfig networkAgentConfig = new NetworkAgentConfig();
-            networkAgentConfig.allowBypass = in.readInt() != 0;
-            networkAgentConfig.explicitlySelected = in.readInt() != 0;
-            networkAgentConfig.acceptUnvalidated = in.readInt() != 0;
-            networkAgentConfig.acceptPartialConnectivity = in.readInt() != 0;
-            networkAgentConfig.subscriberId = in.readString();
-            networkAgentConfig.provisioningNotificationDisabled = in.readInt() != 0;
-            networkAgentConfig.skip464xlat = in.readInt() != 0;
-            networkAgentConfig.legacyType = in.readInt();
-            networkAgentConfig.legacyTypeName = in.readString();
-            networkAgentConfig.legacySubType = in.readInt();
-            networkAgentConfig.legacySubTypeName = in.readString();
-            networkAgentConfig.mLegacyExtraInfo = in.readString();
-            networkAgentConfig.excludeLocalRouteVpn = in.readInt() != 0;
-            networkAgentConfig.mVpnRequiresValidation = in.readInt() != 0;
-            return networkAgentConfig;
-        }
+                @Override
+                public NetworkAgentConfig createFromParcel(Parcel in) {
+                    NetworkAgentConfig networkAgentConfig = new NetworkAgentConfig();
+                    networkAgentConfig.allowBypass = in.readInt() != 0;
+                    networkAgentConfig.explicitlySelected = in.readInt() != 0;
+                    networkAgentConfig.acceptUnvalidated = in.readInt() != 0;
+                    networkAgentConfig.acceptPartialConnectivity = in.readInt() != 0;
+                    networkAgentConfig.subscriberId = in.readString();
+                    networkAgentConfig.provisioningNotificationDisabled = in.readInt() != 0;
+                    networkAgentConfig.skip464xlat = in.readInt() != 0;
+                    networkAgentConfig.legacyType = in.readInt();
+                    networkAgentConfig.legacyTypeName = in.readString();
+                    networkAgentConfig.legacySubType = in.readInt();
+                    networkAgentConfig.legacySubTypeName = in.readString();
+                    networkAgentConfig.mLegacyExtraInfo = in.readString();
+                    networkAgentConfig.excludeLocalRouteVpn = in.readInt() != 0;
+                    networkAgentConfig.mVpnRequiresValidation = in.readInt() != 0;
+                    networkAgentConfig.mSkipNativeNetworkCreation = in.readInt() != 0;
+                    return networkAgentConfig;
+                }
 
-        @Override
-        public NetworkAgentConfig[] newArray(int size) {
-            return new NetworkAgentConfig[size];
-        }
-    };
+                @Override
+                public NetworkAgentConfig[] newArray(int size) {
+                    return new NetworkAgentConfig[size];
+                }
+            };
 }

tests/common/java/android/net/NetworkAgentConfigTest.kt

@@ -20,6 +20,7 @@ import androidx.test.filters.SmallTest
 import androidx.test.runner.AndroidJUnit4
 import com.android.modules.utils.build.SdkLevel.isAtLeastS
 import com.android.modules.utils.build.SdkLevel.isAtLeastT
+import com.android.modules.utils.build.SdkLevel.isAtLeastV
 import com.android.testutils.ConnectivityModuleTest
 import com.android.testutils.assertParcelingIsLossless
 import org.junit.Assert.assertEquals
@@ -47,6 +48,9 @@ class NetworkAgentConfigTest {
                 setLocalRoutesExcludedForVpn(true)
                 setVpnRequiresValidation(true)
             }
+            if (isAtLeastV()) {
+                setSkipNativeNetworkCreation(true)
+            }
         }.build()
         assertParcelingIsLossless(config)
     }
@@ -71,6 +75,9 @@ class NetworkAgentConfigTest {
                 setLocalRoutesExcludedForVpn(true)
                 setVpnRequiresValidation(true)
             }
+            if (isAtLeastV()) {
+                setSkipNativeNetworkCreation(true)
+            }
         }.build()
 
         assertTrue(config.isExplicitlySelected())
@@ -79,6 +86,9 @@ class NetworkAgentConfigTest {
         assertFalse(config.isPartialConnectivityAcceptable())
         assertTrue(config.isUnvalidatedConnectivityAcceptable())
         assertEquals("TEST_NETWORK", config.getLegacyTypeName())
+        if (isAtLeastV()) {
+            assertTrue(config.shouldSkipNativeNetworkCreation())
+        }
         if (isAtLeastT()) {
             assertTrue(config.areLocalRoutesExcludedForVpn())
             assertTrue(config.isVpnValidationRequired())