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/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<()> {