Skeleton for IVmTethering service

Bug: 340376953
Test: adb shell /apex/com.android.virt/bin/vm run-microdroid --network-supported
Change-Id: Idab701f3c684e62629bfe02b7a6ad7904d311f14
diff --git a/java/service/Android.bp b/java/service/Android.bp
index 8bac7be..814445c 100644
--- a/java/service/Android.bp
+++ b/java/service/Android.bp
@@ -31,6 +31,7 @@
     ],
     static_libs: [
         "android.system.virtualizationmaintenance-java",
+        "android.system.vmtethering-java",
     ],
     sdk_version: "core_platform",
     apex_available: ["com.android.virt"],
diff --git a/java/service/src/com/android/system/virtualmachine/VirtualizationSystemService.java b/java/service/src/com/android/system/virtualmachine/VirtualizationSystemService.java
index 2461755..4903b1c 100644
--- a/java/service/src/com/android/system/virtualmachine/VirtualizationSystemService.java
+++ b/java/service/src/com/android/system/virtualmachine/VirtualizationSystemService.java
@@ -26,6 +26,7 @@
 import android.os.ServiceManager;
 import android.os.UserHandle;
 import android.system.virtualizationmaintenance.IVirtualizationMaintenance;
+import android.system.vmtethering.IVmTethering;
 import android.util.Log;
 
 import com.android.internal.os.BackgroundThread;
@@ -40,17 +41,19 @@
  */
 public class VirtualizationSystemService extends SystemService {
     private static final String TAG = VirtualizationSystemService.class.getName();
-    private static final String SERVICE_NAME = "android.system.virtualizationmaintenance";
+    private static final String MAINTENANCE_SERVICE_NAME =
+            "android.system.virtualizationmaintenance";
     private Handler mHandler;
+    private final TetheringService mTetheringService;
 
     public VirtualizationSystemService(Context context) {
         super(context);
+        mTetheringService = new TetheringService();
     }
 
     @Override
     public void onStart() {
-        // Nothing needed here - we don't expose any binder service. The binder service we use is
-        // exposed as a lazy service by the virtualizationservice native binary.
+        publishBinderService(IVmTethering.DESCRIPTOR, mTetheringService);
     }
 
     @Override
@@ -82,11 +85,11 @@
     }
 
     static IVirtualizationMaintenance connectToMaintenanceService() {
-        IBinder binder = ServiceManager.waitForService(SERVICE_NAME);
+        IBinder binder = ServiceManager.waitForService(MAINTENANCE_SERVICE_NAME);
         IVirtualizationMaintenance maintenance =
                 IVirtualizationMaintenance.Stub.asInterface(binder);
         if (maintenance == null) {
-            throw new IllegalStateException("Failed to connect to " + SERVICE_NAME);
+            throw new IllegalStateException("Failed to connect to " + MAINTENANCE_SERVICE_NAME);
         }
         return maintenance;
     }
@@ -136,4 +139,11 @@
             }
         }
     }
+
+    private static final class TetheringService extends IVmTethering.Stub {
+        @Override
+        public void enableVmTethering() throws UnsupportedOperationException {
+            throw new UnsupportedOperationException("VM tethering is not supported yet");
+        }
+    }
 }
diff --git a/virtualizationservice/Android.bp b/virtualizationservice/Android.bp
index 0c39501..f9034af 100644
--- a/virtualizationservice/Android.bp
+++ b/virtualizationservice/Android.bp
@@ -30,6 +30,7 @@
         "android.system.virtualizationservice-rust",
         "android.system.virtualizationservice_internal-rust",
         "android.system.virtualmachineservice-rust",
+        "android.system.vmtethering-rust",
         "android.os.permissions_aidl-rust",
         "libandroid_logger",
         "libanyhow",
diff --git a/virtualizationservice/aidl/Android.bp b/virtualizationservice/aidl/Android.bp
index fb89772..bca4512 100644
--- a/virtualizationservice/aidl/Android.bp
+++ b/virtualizationservice/aidl/Android.bp
@@ -86,6 +86,26 @@
 }
 
 aidl_interface {
+    name: "android.system.vmtethering",
+    srcs: ["android/system/vmtethering/**/*.aidl"],
+    unstable: true,
+    backend: {
+        java: {
+            sdk_version: "module_current",
+            apex_available: [
+                "com.android.virt",
+            ],
+        },
+        rust: {
+            enabled: true,
+            apex_available: [
+                "com.android.virt",
+            ],
+        },
+    },
+}
+
+aidl_interface {
     name: "android.system.virtualmachineservice",
     srcs: ["android/system/virtualmachineservice/**/*.aidl"],
     imports: [
diff --git a/virtualizationservice/aidl/android/system/vmtethering/IVmTethering.aidl b/virtualizationservice/aidl/android/system/vmtethering/IVmTethering.aidl
new file mode 100644
index 0000000..732a515
--- /dev/null
+++ b/virtualizationservice/aidl/android/system/vmtethering/IVmTethering.aidl
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.system.vmtethering;
+
+interface IVmTethering {
+    /**
+     * Start VM tethering to provide external network to VM.
+     */
+    void enableVmTethering();
+}
diff --git a/virtualizationservice/src/aidl.rs b/virtualizationservice/src/aidl.rs
index 241baa5..833c535 100644
--- a/virtualizationservice/src/aidl.rs
+++ b/virtualizationservice/src/aidl.rs
@@ -25,6 +25,7 @@
 use android_system_virtualizationservice::aidl::android::system::virtualizationservice;
 use android_system_virtualizationservice_internal as android_vs_internal;
 use android_system_virtualmachineservice::aidl::android::system::virtualmachineservice;
+use android_system_vmtethering::aidl::android::system::vmtethering;
 use android_vs_internal::aidl::android::system::virtualizationservice_internal;
 use anyhow::{anyhow, ensure, Context, Result};
 use avflog::LogResult;
@@ -73,6 +74,7 @@
     IVmnic::{BpVmnic, IVmnic},
 };
 use virtualmachineservice::IVirtualMachineService::VM_TOMBSTONES_SERVICE_PORT;
+use vmtethering::IVmTethering::{BpVmTethering, IVmTethering};
 use vsock::{VsockListener, VsockStream};
 
 /// The unique ID of a VM used (together with a port number) for vsock communication.
@@ -163,6 +165,9 @@
     static ref NETWORK_SERVICE: Strong<dyn IVmnic> =
         wait_for_interface(<BpVmnic as IVmnic>::get_descriptor())
             .expect("Could not connect to Vmnic");
+    static ref TETHERING_SERVICE: Strong<dyn IVmTethering> =
+        wait_for_interface(<BpVmTethering as IVmTethering>::get_descriptor())
+            .expect("Could not connect to VmTethering");
 }
 
 fn is_valid_guest_cid(cid: Cid) -> bool {
@@ -519,7 +524,19 @@
             ))
             .with_log();
         }
-        NETWORK_SERVICE.createTapInterface(iface_name_suffix)
+        let tap_fd = NETWORK_SERVICE.createTapInterface(iface_name_suffix)?;
+
+        // TODO(340377643): Enabling tethering should be for bridge interface, not TAP interface.
+        let ret = TETHERING_SERVICE.enableVmTethering();
+        if let Err(e) = ret {
+            if e.exception_code() == ExceptionCode::UNSUPPORTED_OPERATION {
+                warn!("{}", e.get_description());
+            } else {
+                return Err(e);
+            }
+        }
+
+        Ok(tap_fd)
     }
 
     fn deleteTapInterface(&self, tap_fd: &ParcelFileDescriptor) -> binder::Result<()> {