Skeleton for IVmTethering service with flag guarding

This reverts commit f9676878292a49caa03e5270c3be2769b029db60.

Bug: 340376953
Test: adb shell /apex/com.android.virt/bin/vm run-microdroid --network-supported

Change-Id: I9c859dd43e7ba7c852a71afce8f36ca10477ad24
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 70da37b..c0e1cc7 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 {
@@ -523,7 +528,20 @@
             ))
             .with_log();
         }
-        NETWORK_SERVICE.createTapInterface(iface_name_suffix)
+        let tap_fd = NETWORK_SERVICE.createTapInterface(iface_name_suffix)?;
+
+        // TODO(340377643): Due to lack of implementation of creating bridge interface, tethering is
+        // enabled for TAP interface instead of bridge interface. After introducing creation of
+        // bridge interface in AVF, we should modify it.
+        if let Err(e) = TETHERING_SERVICE.enableVmTethering() {
+            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<()> {