diff --git a/tetheroffload/aidl/Android.bp b/tetheroffload/aidl/Android.bp
new file mode 100644
index 0000000..1d80586
--- /dev/null
+++ b/tetheroffload/aidl/Android.bp
@@ -0,0 +1,27 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+aidl_interface {
+    name: "android.hardware.tetheroffload",
+    vendor_available: true,
+    srcs: ["android/hardware/tetheroffload/*.aidl"],
+    stability: "vintf",
+    backend: {
+        cpp: {
+            enabled: false,
+        },
+        java: {
+            sdk_version: "module_current",
+            apex_available: [
+                "com.android.tethering",
+            ],
+            min_sdk_version: "30",
+            enabled: true,
+        },
+        ndk: {
+            apps_enabled: false,
+        },
+    },
+    frozen: false,
+}
diff --git a/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/ForwardedStats.aidl b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/ForwardedStats.aidl
new file mode 100644
index 0000000..493a698
--- /dev/null
+++ b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/ForwardedStats.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.tetheroffload;
+@VintfStability
+parcelable ForwardedStats {
+  long rxBytes;
+  long txBytes;
+}
diff --git a/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/IOffload.aidl b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/IOffload.aidl
new file mode 100644
index 0000000..9a58b1f
--- /dev/null
+++ b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/IOffload.aidl
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.tetheroffload;
+@VintfStability
+interface IOffload {
+  void initOffload(in ParcelFileDescriptor fd1, in ParcelFileDescriptor fd2, in android.hardware.tetheroffload.ITetheringOffloadCallback cb);
+  void stopOffload();
+  void setLocalPrefixes(in String[] prefixes);
+  android.hardware.tetheroffload.ForwardedStats getForwardedStats(in String upstream);
+  void setDataWarningAndLimit(in String upstream, in long warningBytes, in long limitBytes);
+  void setUpstreamParameters(in String iface, in String v4Addr, in String v4Gw, in String[] v6Gws);
+  void addDownstream(in String iface, in String prefix);
+  void removeDownstream(in String iface, in String prefix);
+  const int ERROR_CODE_UNUSED = 0;
+}
diff --git a/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/IPv4AddrPortPair.aidl b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/IPv4AddrPortPair.aidl
new file mode 100644
index 0000000..2b42f0c
--- /dev/null
+++ b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/IPv4AddrPortPair.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.tetheroffload;
+@VintfStability
+parcelable IPv4AddrPortPair {
+  String addr;
+  int port;
+}
diff --git a/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/ITetheringOffloadCallback.aidl b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/ITetheringOffloadCallback.aidl
new file mode 100644
index 0000000..4eb7d04
--- /dev/null
+++ b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/ITetheringOffloadCallback.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.tetheroffload;
+@VintfStability
+interface ITetheringOffloadCallback {
+  oneway void onEvent(in android.hardware.tetheroffload.OffloadCallbackEvent event);
+  oneway void updateTimeout(in android.hardware.tetheroffload.NatTimeoutUpdate params);
+}
diff --git a/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/NatTimeoutUpdate.aidl b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/NatTimeoutUpdate.aidl
new file mode 100644
index 0000000..9eddaa2
--- /dev/null
+++ b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/NatTimeoutUpdate.aidl
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.tetheroffload;
+@VintfStability
+parcelable NatTimeoutUpdate {
+  android.hardware.tetheroffload.IPv4AddrPortPair src;
+  android.hardware.tetheroffload.IPv4AddrPortPair dst;
+  android.hardware.tetheroffload.NetworkProtocol proto;
+}
diff --git a/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/NetworkProtocol.aidl b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/NetworkProtocol.aidl
new file mode 100644
index 0000000..52bd2a6
--- /dev/null
+++ b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/NetworkProtocol.aidl
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.tetheroffload;
+@Backing(type="int") @VintfStability
+enum NetworkProtocol {
+  TCP = 6,
+  UDP = 17,
+}
diff --git a/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/OffloadCallbackEvent.aidl b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/OffloadCallbackEvent.aidl
new file mode 100644
index 0000000..026e18e
--- /dev/null
+++ b/tetheroffload/aidl/aidl_api/android.hardware.tetheroffload/current/android/hardware/tetheroffload/OffloadCallbackEvent.aidl
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.tetheroffload;
+@Backing(type="int") @VintfStability
+enum OffloadCallbackEvent {
+  OFFLOAD_STARTED = 1,
+  OFFLOAD_STOPPED_ERROR = 2,
+  OFFLOAD_STOPPED_UNSUPPORTED = 3,
+  OFFLOAD_SUPPORT_AVAILABLE = 4,
+  OFFLOAD_STOPPED_LIMIT_REACHED = 5,
+  OFFLOAD_WARNING_REACHED = 6,
+}
diff --git a/tetheroffload/aidl/android/hardware/tetheroffload/ForwardedStats.aidl b/tetheroffload/aidl/android/hardware/tetheroffload/ForwardedStats.aidl
new file mode 100644
index 0000000..d2fe49b
--- /dev/null
+++ b/tetheroffload/aidl/android/hardware/tetheroffload/ForwardedStats.aidl
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2022 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.hardware.tetheroffload;
+
+@VintfStability
+parcelable ForwardedStats {
+    /**
+     * Tx/Rx forwarded bytes
+     */
+    long rxBytes;
+    long txBytes;
+}
diff --git a/tetheroffload/aidl/android/hardware/tetheroffload/IOffload.aidl b/tetheroffload/aidl/android/hardware/tetheroffload/IOffload.aidl
new file mode 100644
index 0000000..30b2c8d
--- /dev/null
+++ b/tetheroffload/aidl/android/hardware/tetheroffload/IOffload.aidl
@@ -0,0 +1,284 @@
+/*
+ * Copyright (C) 2022 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.hardware.tetheroffload;
+
+import android.hardware.tetheroffload.ForwardedStats;
+import android.hardware.tetheroffload.ITetheringOffloadCallback;
+
+/**
+ * Interface used to control tethering offload.
+ */
+@VintfStability
+interface IOffload {
+    /**
+     * Error code for all {@code ServiceSpecificException}s thrown by this interface.
+     */
+    const int ERROR_CODE_UNUSED = 0;
+
+    /**
+     * Indicates intent to start offload for tethering in immediate future.
+     *
+     * This API must be called exactly once the first time that Tethering is requested by
+     * the user.
+     *
+     * If this API is called multiple times without first calling stopOffload, then the subsequent
+     * calls must fail without changing the state of the server.
+     *
+     * If for some reason, the hardware is currently unable to support offload, this call must fail.
+     *
+     * @param fd1 A file descriptor bound to the following netlink groups
+     *            (NF_NETLINK_CONNTRACK_NEW | NF_NETLINK_CONNTRACK_DESTROY).
+     * @param fd2 A file descriptor bound to the following netlink groups
+     *            (NF_NETLINK_CONNTRACK_UPDATE | NF_NETLINK_CONNTRACK_DESTROY).
+     * @param cb Assuming success, this callback must provide unsolicited updates of offload status.
+     *           It is assumed to be valid until stopOffload is called.
+     *
+     * @throws:
+     *         - EX_ILLEGAL_ARGUMENT if any file descriptors are invalid.
+     *         - EX_ILLEGAL_STATE if this method previously succeeded and stopOffload() was not
+     *           later called.
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     *
+     * Remarks: Initializing offload does not imply that any upstreams or downstreams have yet been,
+     * or even will be, chosen.  This API is symmetrical with stopOffload.
+     */
+    void initOffload(in ParcelFileDescriptor fd1, in ParcelFileDescriptor fd2,
+            in ITetheringOffloadCallback cb);
+
+    /**
+     * Indicate desire to tear down all tethering offload.
+     *
+     * Called after tethering is no longer requested by the user. Any remaining offload must
+     * be subsequently torn down by the management process.  Upon success, the callback registered
+     * in initOffload must be released, and offload must be stopped.
+     *
+     * @throws:
+     *         - EX_ILLEGAL_STATE if initOffload() was not called, or if stopOffload() was already
+     *           called.
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     *
+     * Remarks: Statistics must be reset by this API.
+     */
+    void stopOffload();
+
+    /**
+     * Instruct management process not to forward traffic destined to or from the specified
+     * prefixes.
+     *
+     * This API may only be called after initOffload and before stopOffload.
+     *
+     * @param prefixes List containing fully specified prefixes. For e.g. 192.168.1.0/24
+     * or 2001:4860:684::/64
+     *
+     * @throws:
+     *         - EX_ILLEGAL_ARGUMENT if the IP prefixes are invalid.
+     *         - EX_ILLEGAL_STATE if this method is called before initOffload(), or if this method
+     *           is called after stopOffload().
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     *
+     * Remarks: This list overrides any previously specified list
+     */
+    void setLocalPrefixes(in String[] prefixes);
+
+    /**
+     * Query offloaded traffic statistics forwarded to an upstream address.
+     *
+     * Return statistics that have transpired since the last query.  This would include
+     * statistics from all offloaded downstream tether interfaces that have been forwarded to this
+     * upstream interface.  After returning the statistics, the counters are reset to zero.
+     *
+     * Only offloaded statistics must be returned by this API, software stats must not be
+     * returned.
+     *
+     * @param upstream Upstream interface on which traffic exited/entered
+     *
+     * @return ForwardedStats depicting the received and transmitted bytes
+     *
+     * @throws:
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     */
+    ForwardedStats getForwardedStats(in String upstream);
+
+    /**
+     * Instruct hardware to send callbacks, and possibly stop offload, after certain number of bytes
+     * have been transferred in either direction on this upstream interface.
+     *
+     * The specified quota bytes must be applied to all traffic on the given upstream interface.
+     * This includes hardware forwarded traffic, software forwarded traffic, and AP-originated
+     * traffic. IPv4 and IPv6 traffic both count towards the same quota. IP headers are included
+     * in the byte count quota, but, link-layer headers are not.
+     *
+     * This API may only be called while offload is occurring on this upstream. The hardware
+     * management process MUST NOT store the values when offload is not started and apply them
+     * once offload is started. This is because the quota values would likely become stale over
+     * time and would not reflect any new traffic that has occurred.
+     *
+     * The specified quota bytes MUST replace any previous quotas set by
+     * {@code setDataWarningAndLimit} specified on the same interface. It may be interpreted as
+     * "tell me when either <warningBytes> or <limitBytes> bytes have been transferred
+     * (in either direction), and stop offload when <limitBytes> bytes have been transferred,
+     * starting now and counting from zero on <upstream>."
+     *
+     * Once the {@code warningBytes} is reached, the callback registered in initOffload must be
+     * called with {@code OFFLOAD_WARNING_REACHED} to indicate this event. Once the event fires
+     * for this upstream, no further {@code OFFLOAD_WARNING_REACHED} event will be fired for this
+     * upstream unless this method is called again with the same interface. Note that there is
+     * no need to call initOffload again to resume offload if stopOffload was not called by the
+     * client.
+     *
+     * Similarly, Once the {@code limitBytes} is reached, the callback registered in initOffload
+     * must be called with {@code OFFLOAD_STOPPED_LIMIT_REACHED} to indicate this event. Once
+     * the event fires for this upstream, no further {@code OFFLOAD_STOPPED_LIMIT_REACHED}
+     * event will be fired for this upstream unless this method is called again with the same
+     * interface. However, unlike {@code warningBytes}, when {@code limitBytes} is reached,
+     * all offload must be stopped. If offload is desired again, the hardware management
+     * process must be completely reprogrammed by calling setUpstreamParameters and
+     * addDownstream again.
+     *
+     * Note that {@code warningBytes} must always be less than or equal to {@code limitBytes},
+     * when {@code warningBytes} is reached, {@code limitBytes} may still valid unless this method
+     * is called again with the same interface.
+     *
+     * @param upstream Upstream interface name that quota must apply to.
+     * @param warningBytes The quota of warning, defined as the number of bytes, starting from
+     *                     zero and counting from now.
+     * @param limitBytes The quota of limit, defined as the number of bytes, starting from zero
+     *                   and counting from now.
+     *
+     * @throws:
+     *         - EX_ILLEGAL_ARGUMENT if any parameters are invalid (such as invalid upstream
+     *           or negative number of bytes).
+     *         - EX_ILLEGAL_STATE if this method is called before initOffload(), or if this method
+     *           is called after stopOffload().
+     *         - EX_UNSUPPORTED_OPERATION if it is not supported.
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     */
+    void setDataWarningAndLimit(in String upstream, in long warningBytes, in long limitBytes);
+
+    /**
+     * Instruct hardware to start forwarding traffic to the specified upstream.
+     *
+     * When iface, v4Addr, and v4Gw are all non-null, the management process may begin forwarding
+     * any currently configured or future configured IPv4 downstreams to this upstream interface.
+     *
+     * If any of the previously three mentioned parameters are null, then any current IPv4 offload
+     * must be stopped.
+     *
+     * When iface and v6Gws are both non-null, and in the case of v6Gws, are not empty, the
+     * management process may begin forwarding any currently configured or future configured IPv6
+     * downstreams to this upstream interface.
+     *
+     * If either of the two above parameters are null, or no V6 Gateways are provided, then IPv6
+     * offload must be stopped.
+     *
+     * This API may only be called after initOffload and before stopOffload.
+     *
+     * @param iface  Upstream interface name.  Note that only one is needed because IPv4 and IPv6
+     *               interfaces cannot be different (only known that this can occur during software
+     *               xlat, which cannot be offloaded through hardware anyways).  If the iface is
+     *               null, offload must be stopped.
+     * @param v4Addr The local IPv4 address assigned to the provided upstream interface, i.e. the
+     *               IPv4 address the packets are NATed to. For e.g. 192.168.0.12.
+     * @param v4Gw   The IPv4 address of the IPv4 gateway on the upstream interface.
+     *               For e.g. 192.168.1.1
+     * @param v6Gws  A list of IPv6 addresses (for e.g. fe80::97be:9de7:b24b:9194) for possible IPv6
+     *               gateways on the upstream interface.
+     *
+     * @throws:
+     *         - EX_ILLEGAL_ARGUMENT if any parameters are invalid (such as invalid upstream
+     *           or IP addresses).
+     *         - EX_ILLEGAL_STATE if this method is called before initOffload(), or if this method
+     *           is called after stopOffload().
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     *
+     * Remarks: This overrides any previously configured parameters.
+     */
+    void setUpstreamParameters(
+            in String iface, in String v4Addr, in String v4Gw, in String[] v6Gws);
+
+    /**
+     * Configure a downstream interface and prefix in the hardware management process that may be
+     * forwarded.
+     *
+     * The prefix may be an IPv4 or an IPv6 prefix to signify which family can be offloaded from
+     * the specified tether interface.  The list of IPv4 and IPv6 downstreams that are configured
+     * may differ.
+     *
+     * If the given protocol, as determined by the prefix, has an upstream set,
+     * the hardware may begin forwarding traffic between the upstream and any devices on the
+     * downstream interface that have IP addresses within the specified prefix. Other traffic from
+     * the same downstream interfaces is unaffected and must be forwarded if and only if it was
+     * already being forwarded.
+     *
+     * If no upstream is currently configured, then these downstream interface and prefixes must be
+     * preserved so that offload may begin in the future when an upstream is set.
+     *
+     * This API does not replace any previously configured downstreams and any such downstreams must
+     * be explicitly removed by calling removeDownstream.
+     *
+     * This API may only be called after initOffload and before stopOffload.
+     *
+     * @param iface  Downstream interface
+     * @param prefix Downstream prefix depicting addresses that may be offloaded.
+     *               For e.g. 192.168.1.0/24 or 2001:4860:684::/64)
+     *
+     * @throws:
+     *         - EX_ILLEGAL_ARGUMENT if any parameters are invalid (such as invalid downstream
+     *           or IP prefix).
+     *         - EX_ILLEGAL_STATE if this method is called before initOffload(), or if this method
+     *           is called after stopOffload().
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     *
+     * Remarks: The hardware management process may fail this call in a normal situation.  This can
+     *          happen because the hardware cannot support the current number of prefixes, the
+     *          hardware cannot support concurrent offload on multiple interfaces, the hardware
+     *          cannot currently support offload on the tether interface for some reason, or any
+     *          other dynamic configuration issues which may occur.  In this case,
+     *          traffic must remain unaffected and must be forwarded if and only if it was already
+     *          being forwarded.
+     */
+    void addDownstream(in String iface, in String prefix);
+
+    /**
+     * Remove a downstream prefix that may be forwarded from the hardware management process.
+     *
+     * The prefix may be an IPv4 or an IPv6 prefix. If it was not previously configured using
+     * addDownstream, then this must be a no-op.
+     *
+     * This API may only be called after initOffload and before stopOffload.
+     *
+     * @param iface  Downstream interface
+     * @param prefix Downstream prefix depicting address that must no longer be offloaded
+     *               For e.g. 192.168.1.0/24 or 2001:4860:684::/64)
+     *
+     * @throws:
+     *         - EX_ILLEGAL_ARGUMENT if any parameters are invalid (such as invalid downstream
+     *           or IP prefix).
+     *         - EX_ILLEGAL_STATE if this method is called before initOffload(), or if this method
+     *           is called after stopOffload().
+     *         - EX_SERVICE_SPECIFIC with the error message set to a human-readable reason for the
+     *           error.
+     */
+    void removeDownstream(in String iface, in String prefix);
+}
diff --git a/tetheroffload/aidl/android/hardware/tetheroffload/IPv4AddrPortPair.aidl b/tetheroffload/aidl/android/hardware/tetheroffload/IPv4AddrPortPair.aidl
new file mode 100644
index 0000000..16d7d85
--- /dev/null
+++ b/tetheroffload/aidl/android/hardware/tetheroffload/IPv4AddrPortPair.aidl
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2022 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.hardware.tetheroffload;
+
+@VintfStability
+parcelable IPv4AddrPortPair {
+    /**
+     * IPv4 Address and Port
+     */
+    String addr;
+    int port;
+}
diff --git a/tetheroffload/aidl/android/hardware/tetheroffload/ITetheringOffloadCallback.aidl b/tetheroffload/aidl/android/hardware/tetheroffload/ITetheringOffloadCallback.aidl
new file mode 100644
index 0000000..5ee819b
--- /dev/null
+++ b/tetheroffload/aidl/android/hardware/tetheroffload/ITetheringOffloadCallback.aidl
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2022 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.hardware.tetheroffload;
+
+import android.hardware.tetheroffload.NatTimeoutUpdate;
+import android.hardware.tetheroffload.OffloadCallbackEvent;
+
+/**
+ * Callback providing information about status of hardware management process
+ * as well as providing a way to keep offloaded connections from timing out.
+ */
+@VintfStability
+oneway interface ITetheringOffloadCallback {
+    /**
+     * Called when an asynchronous event is generated by the hardware
+     * management process.
+     */
+    void onEvent(in OffloadCallbackEvent event);
+
+    /**
+     *  Provide a way for the management process to request that a connections
+     *  timeout be updated in kernel.
+     *
+     *  This is necessary to ensure that offloaded traffic is not cleaned up
+     *  by the kernel connection tracking module for IPv4.
+     */
+    void updateTimeout(in NatTimeoutUpdate params);
+}
diff --git a/tetheroffload/aidl/android/hardware/tetheroffload/NatTimeoutUpdate.aidl b/tetheroffload/aidl/android/hardware/tetheroffload/NatTimeoutUpdate.aidl
new file mode 100644
index 0000000..50805ef
--- /dev/null
+++ b/tetheroffload/aidl/android/hardware/tetheroffload/NatTimeoutUpdate.aidl
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2022 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.hardware.tetheroffload;
+
+import android.hardware.tetheroffload.IPv4AddrPortPair;
+import android.hardware.tetheroffload.NetworkProtocol;
+
+@VintfStability
+parcelable NatTimeoutUpdate {
+    IPv4AddrPortPair src;
+    IPv4AddrPortPair dst;
+    NetworkProtocol proto;
+}
diff --git a/tetheroffload/aidl/android/hardware/tetheroffload/NetworkProtocol.aidl b/tetheroffload/aidl/android/hardware/tetheroffload/NetworkProtocol.aidl
new file mode 100644
index 0000000..cc4f7ac
--- /dev/null
+++ b/tetheroffload/aidl/android/hardware/tetheroffload/NetworkProtocol.aidl
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2022 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.hardware.tetheroffload;
+
+@VintfStability
+@Backing(type="int")
+enum NetworkProtocol {
+    TCP = 6,
+    UDP = 17,
+}
diff --git a/tetheroffload/aidl/android/hardware/tetheroffload/OffloadCallbackEvent.aidl b/tetheroffload/aidl/android/hardware/tetheroffload/OffloadCallbackEvent.aidl
new file mode 100644
index 0000000..a95f674
--- /dev/null
+++ b/tetheroffload/aidl/android/hardware/tetheroffload/OffloadCallbackEvent.aidl
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2022 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.hardware.tetheroffload;
+
+@VintfStability
+@Backing(type="int")
+enum OffloadCallbackEvent {
+    /**
+     * Indicate that a working configuration has been programmed and the
+     * hardware management process has begun forwarding traffic.
+     */
+    OFFLOAD_STARTED = 1,
+    /**
+     * Indicate that an error has occurred which has disrupted hardware
+     * acceleration.  Software routing may still be attempted; however,
+     * statistics may be temporarily unavailable.  Statistics may be recovered
+     * after OFFLOAD_SUPPORT_AVAILABLE event is fired.
+     */
+    OFFLOAD_STOPPED_ERROR = 2,
+    /**
+     * Indicate that the device has moved to a RAT on which hardware
+     * acceleration is not supported.  Subsequent calls to setUpstreamParameters
+     * and add/removeDownstream will likely fail and cannot be presumed to be
+     * saved inside of the hardware management process.  Upon receiving
+     * OFFLOAD_SUPPORT_AVAILABLE, the client may reprogram the hardware
+     * management process to begin offload again.
+     */
+    OFFLOAD_STOPPED_UNSUPPORTED = 3,
+    /**
+     * Indicate that the hardware management process is willing and able to
+     * provide support for hardware acceleration at this time.  If applicable,
+     * the client may query for statistics.  If offload is desired, the client
+     * must reprogram the hardware management process.
+     */
+    OFFLOAD_SUPPORT_AVAILABLE = 4,
+    /**
+     * Hardware acceleration is no longer in effect and must be reprogrammed
+     * in order to resume.  This event is fired when the limit, applied in
+     * setDataLimit, has expired.  It is recommended that the client query for
+     * statistics immediately after receiving this event.
+     */
+    OFFLOAD_STOPPED_LIMIT_REACHED = 5,
+    /**
+     * This event is fired when the quota, applied in setDataWarning, has expired. It is
+     * recommended that the client query for statistics immediately after receiving this event.
+     * Any offloaded traffic will continue to be offloaded until offload is stopped or
+     * OFFLOAD_STOPPED_LIMIT_REACHED is sent.
+     */
+    OFFLOAD_WARNING_REACHED = 6,
+}
diff --git a/tetheroffload/aidl/default/Android.bp b/tetheroffload/aidl/default/Android.bp
new file mode 100644
index 0000000..8f0739c
--- /dev/null
+++ b/tetheroffload/aidl/default/Android.bp
@@ -0,0 +1,36 @@
+// Copyright (C) 2022 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 {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_binary {
+    name: "android.hardware.tetheroffload-service.example",
+    relative_install_path: "hw",
+    init_rc: ["tetheroffload-example.rc"],
+    vintf_fragments: ["tetheroffload-example.xml"],
+    vendor: true,
+    shared_libs: [
+        "android.hardware.tetheroffload-V1-ndk",
+        "libbase",
+        "libbinder_ndk",
+        "libcutils",
+        "libutils",
+    ],
+    srcs: [
+        "main.cpp",
+        "Offload.cpp",
+    ],
+}
diff --git a/tetheroffload/aidl/default/Offload.cpp b/tetheroffload/aidl/default/Offload.cpp
new file mode 100644
index 0000000..8aa6916
--- /dev/null
+++ b/tetheroffload/aidl/default/Offload.cpp
@@ -0,0 +1,246 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+#include <numeric>
+#include <string>
+
+#include <android-base/logging.h>
+#include <android-base/strings.h>
+#include <netdb.h>
+
+#include "Offload.h"
+
+namespace aidl::android::hardware::tetheroffload::impl::example {
+
+using ::android::base::Join;
+
+ndk::ScopedAStatus Offload::addDownstream(const std::string& in_iface,
+                                          const std::string& in_prefix) {
+    LOG(VERBOSE) << __func__ << " Interface: " << in_iface << ", Prefix: " << in_prefix;
+    if (!isInitialized()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(
+                EX_ILLEGAL_STATE, "Tetheroffload HAL not initialized");
+    }
+    if (!isValidInterface(in_iface)) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Invalid interface name");
+    }
+    if (!isValidIpPrefix(in_prefix)) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Invalid IP prefix");
+    }
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus Offload::getForwardedStats(const std::string& in_upstream,
+                                              ForwardedStats* _aidl_return) {
+    LOG(VERBOSE) << __func__ << " Upstream: " << in_upstream;
+    ForwardedStats stats;
+    stats.rxBytes = 0;
+    stats.txBytes = 0;
+    *_aidl_return = std::move(stats);
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus Offload::initOffload(const ndk::ScopedFileDescriptor& in_fd1,
+                                        const ndk::ScopedFileDescriptor& in_fd2,
+                                        const std::shared_ptr<ITetheringOffloadCallback>& in_cb) {
+    LOG(VERBOSE) << __func__ << " FileDescriptor1: " << std::to_string(in_fd1.get())
+                 << ", FileDescriptor2: " << std::to_string(in_fd2.get())
+                 << ", ITetheringOffloadCallback: " << in_cb;
+    if (isInitialized()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(
+                EX_ILLEGAL_STATE, "Tetheroffload HAL already initialized");
+    }
+    int fd1 = in_fd1.get();
+    int fd2 = in_fd2.get();
+    if (fd1 < 0 || fd2 < 0) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Invalid file descriptors");
+    }
+    mFd1 = ndk::ScopedFileDescriptor(dup(fd1));
+    mFd2 = ndk::ScopedFileDescriptor(dup(fd2));
+    mInitialized = true;
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus Offload::removeDownstream(const std::string& in_iface,
+                                             const std::string& in_prefix) {
+    LOG(VERBOSE) << __func__ << " Interface: " << in_iface << ", Prefix: " << in_prefix;
+    if (!isInitialized()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(
+                EX_ILLEGAL_STATE, "Tetheroffload HAL not initialized");
+    }
+    if (!isValidIpPrefix(in_prefix)) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Invalid IP prefix");
+    }
+    if (!isValidInterface(in_iface)) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Invalid interface name");
+    }
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus Offload::setDataWarningAndLimit(const std::string& in_upstream,
+                                                   int64_t in_warningBytes, int64_t in_limitBytes) {
+    LOG(VERBOSE) << __func__ << " Upstream: " << in_upstream
+                 << ", WarningBytes: " << in_warningBytes << ", LimitBytes: " << in_limitBytes;
+    if (!isInitialized()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(
+                EX_ILLEGAL_STATE, "Tetheroffload HAL not initialized");
+    }
+    if (!isValidInterface(in_upstream)) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Invalid interface name");
+    }
+    if (in_warningBytes < 0 || in_limitBytes < 0) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Threshold must be non-negative");
+    }
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus Offload::setLocalPrefixes(const std::vector<std::string>& in_prefixes) {
+    LOG(VERBOSE) << __func__ << " Prefixes: " << Join(in_prefixes, ',');
+    if (!isInitialized()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(
+                EX_ILLEGAL_STATE, "Tetheroffload HAL not initialized");
+    }
+    if (in_prefixes.empty()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "No IP prefix");
+    }
+    for (std::string prefix : in_prefixes) {
+        if (!isValidIpPrefix(prefix)) {
+            return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                    "Invalid IP prefix");
+        }
+    }
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus Offload::setUpstreamParameters(const std::string& in_iface,
+                                                  const std::string& in_v4Addr,
+                                                  const std::string& in_v4Gw,
+                                                  const std::vector<std::string>& in_v6Gws) {
+    LOG(VERBOSE) << __func__ << " Interface: " << in_iface << ", IPv4Address: " << in_v4Addr
+                 << ", IPv4Gateway: " << in_v4Gw << ", IPv6Gateways: " << Join(in_v6Gws, ',');
+    if (!isInitialized()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(
+                EX_ILLEGAL_STATE, "Tetheroffload HAL not initialized");
+    }
+    if (!isValidInterface(in_iface)) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "Invalid interface name");
+    }
+    if (in_v4Addr.empty() && in_v4Gw.empty() && in_v6Gws.empty()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                "No upstream IP address");
+    }
+    if (!in_v4Addr.empty() && !in_v4Gw.empty()) {
+        if (!isValidIpv4Address(in_v4Addr) || !isValidIpv4Address(in_v4Gw)) {
+            return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                    "Invalid IP address");
+        }
+    }
+    for (std::string ip : in_v6Gws) {
+        if (!isValidIpv6Address(ip)) {
+            return ndk::ScopedAStatus::fromExceptionCodeWithMessage(EX_ILLEGAL_ARGUMENT,
+                                                                    "Invalid IP address");
+        }
+    }
+    return ndk::ScopedAStatus::ok();
+}
+
+ndk::ScopedAStatus Offload::stopOffload() {
+    LOG(VERBOSE) << __func__;
+    if (!isInitialized()) {
+        return ndk::ScopedAStatus::fromExceptionCodeWithMessage(
+                EX_ILLEGAL_STATE, "Tetheroffload HAL not initialized");
+    }
+    mInitialized = false;
+    return ndk::ScopedAStatus::ok();
+};
+
+bool Offload::isInitialized() {
+    return (mInitialized == true);
+}
+
+bool Offload::isValidInterface(const std::string& iface) {
+    return !iface.empty() && iface != "invalid";
+}
+
+bool Offload::isValidIpv4Address(const std::string& repr) {
+    return validateIpAddressOrPrefix(repr, AF_INET, false);
+}
+
+bool Offload::isValidIpv4Prefix(const std::string& repr) {
+    return validateIpAddressOrPrefix(repr, AF_INET, true);
+}
+
+bool Offload::isValidIpv6Address(const std::string& repr) {
+    return validateIpAddressOrPrefix(repr, AF_INET6, false);
+}
+
+bool Offload::isValidIpv6Prefix(const std::string& repr) {
+    return validateIpAddressOrPrefix(repr, AF_INET6, true);
+}
+
+bool Offload::isValidIpAddress(const std::string& repr) {
+    return isValidIpv4Address(repr) || isValidIpv6Address(repr);
+}
+
+bool Offload::isValidIpPrefix(const std::string& repr) {
+    return isValidIpv4Prefix(repr) || isValidIpv6Prefix(repr);
+}
+
+// Refer to libnetdutils's IPAddress and IPPrefix classes.
+// Can't use them directly because libnetdutils is not "vendor_available".
+bool Offload::validateIpAddressOrPrefix(const std::string& repr, const int expectedFamily,
+                                        const bool isPrefix) {
+    const addrinfo hints = {
+            .ai_flags = AI_NUMERICHOST | AI_NUMERICSERV,
+    };
+    addrinfo* res;
+    size_t index = repr.find('/');
+    if (isPrefix && index == std::string::npos) return false;
+
+    // Parse the IP address.
+    const std::string ipAddress = isPrefix ? repr.substr(0, index) : repr;
+    const int ret = getaddrinfo(ipAddress.c_str(), nullptr, &hints, &res);
+    if (ret != 0) return false;
+
+    // Check the address family.
+    int family = res[0].ai_family;
+    freeaddrinfo(res);
+    if (family != expectedFamily) return false;
+    if (!isPrefix) return true;
+
+    // Parse the prefix length.
+    const char* prefixString = repr.c_str() + index + 1;
+    if (!isdigit(*prefixString)) return false;
+    char* endptr;
+    unsigned long prefixlen = strtoul(prefixString, &endptr, 10);
+    if (*endptr != '\0') return false;
+
+    uint8_t maxlen = (family == AF_INET) ? 32 : 128;
+    if (prefixlen > maxlen) return false;
+
+    return true;
+}
+
+}  // namespace aidl::android::hardware::tetheroffload::impl::example
diff --git a/tetheroffload/aidl/default/Offload.h b/tetheroffload/aidl/default/Offload.h
new file mode 100644
index 0000000..a1f6bce
--- /dev/null
+++ b/tetheroffload/aidl/default/Offload.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+#pragma once
+
+#include <aidl/android/hardware/tetheroffload/BnOffload.h>
+
+namespace aidl {
+namespace android {
+namespace hardware {
+namespace tetheroffload {
+namespace impl {
+namespace example {
+
+using aidl::android::hardware::tetheroffload::ForwardedStats;
+using aidl::android::hardware::tetheroffload::ITetheringOffloadCallback;
+
+class Offload : public BnOffload {
+  public:
+    ndk::ScopedAStatus addDownstream(const std::string& in_iface,
+                                     const std::string& in_prefix) override;
+    ndk::ScopedAStatus getForwardedStats(const std::string& in_upstream,
+                                         ForwardedStats* _aidl_return) override;
+    ndk::ScopedAStatus initOffload(
+            const ndk::ScopedFileDescriptor& in_fd1, const ndk::ScopedFileDescriptor& in_fd2,
+            const std::shared_ptr<ITetheringOffloadCallback>& in_cb) override;
+    ndk::ScopedAStatus removeDownstream(const std::string& in_iface,
+                                        const std::string& in_prefix) override;
+    ndk::ScopedAStatus setDataWarningAndLimit(const std::string& in_upstream,
+                                              int64_t in_warningBytes,
+                                              int64_t in_limitBytes) override;
+    ndk::ScopedAStatus setLocalPrefixes(const std::vector<std::string>& in_prefixes) override;
+    ndk::ScopedAStatus setUpstreamParameters(const std::string& in_iface,
+                                             const std::string& in_v4Addr,
+                                             const std::string& in_v4Gw,
+                                             const std::vector<std::string>& in_v6Gws) override;
+    ndk::ScopedAStatus stopOffload() override;
+
+  private:
+    bool isInitialized();
+    bool isValidInterface(const std::string& iface);
+    bool isValidIpv4Address(const std::string& repr);
+    bool isValidIpv4Prefix(const std::string& repr);
+    bool isValidIpv6Address(const std::string& repr);
+    bool isValidIpv6Prefix(const std::string& repr);
+    bool isValidIpAddress(const std::string& repr);
+    bool isValidIpPrefix(const std::string& repr);
+    bool validateIpAddressOrPrefix(const std::string& repr, const int expectedFamily,
+                                   const bool isPrefix);
+
+    bool mInitialized = false;
+    ndk::ScopedFileDescriptor mFd1;
+    ndk::ScopedFileDescriptor mFd2;
+};
+
+}  // namespace example
+}  // namespace impl
+}  // namespace tetheroffload
+}  // namespace hardware
+}  // namespace android
+}  // namespace aidl
diff --git a/tetheroffload/aidl/default/main.cpp b/tetheroffload/aidl/default/main.cpp
new file mode 100644
index 0000000..6633630
--- /dev/null
+++ b/tetheroffload/aidl/default/main.cpp
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+#include "Offload.h"
+
+#include <android-base/logging.h>
+#include <android/binder_manager.h>
+#include <android/binder_process.h>
+
+using aidl::android::hardware::tetheroffload::impl::example::Offload;
+
+int main() {
+    ABinderProcess_setThreadPoolMaxThreadCount(0);
+    std::shared_ptr<Offload> offload = ndk::SharedRefBase::make<Offload>();
+
+    binder_status_t status = AServiceManager_addService(
+            offload->asBinder().get(), Offload::makeServiceName("default").c_str());
+    CHECK_EQ(status, STATUS_OK);
+
+    ABinderProcess_joinThreadPool();
+    return EXIT_FAILURE;  // should not reach
+}
diff --git a/tetheroffload/aidl/default/tetheroffload-example.rc b/tetheroffload/aidl/default/tetheroffload-example.rc
new file mode 100644
index 0000000..46cda61
--- /dev/null
+++ b/tetheroffload/aidl/default/tetheroffload-example.rc
@@ -0,0 +1,4 @@
+service vendor.tetheroffload-example /vendor/bin/hw/android.hardware.tetheroffload-service.example
+    class hal
+    user nobody
+    group nobody
diff --git a/tetheroffload/aidl/default/tetheroffload-example.xml b/tetheroffload/aidl/default/tetheroffload-example.xml
new file mode 100644
index 0000000..9fe83f6
--- /dev/null
+++ b/tetheroffload/aidl/default/tetheroffload-example.xml
@@ -0,0 +1,7 @@
+<manifest version="1.0" type="device">
+    <hal format="aidl">
+        <name>android.hardware.tetheroffload</name>
+        <version>1</version>
+        <fqname>IOffload/default</fqname>
+    </hal>
+</manifest>
diff --git a/tetheroffload/aidl/vts/functional/Android.bp b/tetheroffload/aidl/vts/functional/Android.bp
new file mode 100644
index 0000000..c9c1845
--- /dev/null
+++ b/tetheroffload/aidl/vts/functional/Android.bp
@@ -0,0 +1,24 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_test {
+    name: "VtsHalTetheroffloadTargetTest",
+    defaults: [
+        "VtsHalTargetTestDefaults",
+        "use_libaidlvintf_gtest_helper_static",
+    ],
+    srcs: [
+        "VtsHalTetheroffloadTargetTest.cpp",
+    ],
+    shared_libs: [
+        "libbinder_ndk",
+    ],
+    static_libs: [
+        "android.hardware.tetheroffload-V1-ndk",
+        "libgmock_ndk",
+    ],
+    test_suites: [
+        "vts",
+    ],
+}
diff --git a/tetheroffload/aidl/vts/functional/VtsHalTetheroffloadTargetTest.cpp b/tetheroffload/aidl/vts/functional/VtsHalTetheroffloadTargetTest.cpp
new file mode 100644
index 0000000..fc8abbd
--- /dev/null
+++ b/tetheroffload/aidl/vts/functional/VtsHalTetheroffloadTargetTest.cpp
@@ -0,0 +1,689 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+#define LOG_TAG "tetheroffload_aidl_hal_test"
+
+#include <aidl/Gtest.h>
+#include <aidl/Vintf.h>
+#include <aidl/android/hardware/tetheroffload/BnOffload.h>
+#include <aidl/android/hardware/tetheroffload/BnTetheringOffloadCallback.h>
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+#include <android/binder_manager.h>
+#include <android/binder_process.h>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <log/log.h>
+#include <net/if.h>
+#include <sys/socket.h>
+
+namespace aidl::android::hardware::tetheroffload {
+
+namespace {
+
+using ::android::base::unique_fd;
+using android::hardware::tetheroffload::ForwardedStats;
+using android::hardware::tetheroffload::IOffload;
+using android::hardware::tetheroffload::NatTimeoutUpdate;
+using android::hardware::tetheroffload::OffloadCallbackEvent;
+using ::testing::AnyOf;
+using ::testing::Eq;
+
+const std::string TEST_IFACE = "rmnet_data0";
+const unsigned kFd1Groups = NF_NETLINK_CONNTRACK_NEW | NF_NETLINK_CONNTRACK_DESTROY;
+const unsigned kFd2Groups = NF_NETLINK_CONNTRACK_UPDATE | NF_NETLINK_CONNTRACK_DESTROY;
+
+enum class ExpectBoolean {
+    Ignored = -1,
+    False = 0,
+    True = 1,
+};
+
+inline const sockaddr* asSockaddr(const sockaddr_nl* nladdr) {
+    return reinterpret_cast<const sockaddr*>(nladdr);
+}
+
+int netlinkSocket(int protocol, unsigned groups) {
+    unique_fd s(socket(AF_NETLINK, SOCK_DGRAM, protocol));
+    if (s.get() < 0) {
+        return -errno;
+    }
+
+    const struct sockaddr_nl bind_addr = {
+            .nl_family = AF_NETLINK,
+            .nl_pad = 0,
+            .nl_pid = 0,
+            .nl_groups = groups,
+    };
+    if (bind(s.get(), asSockaddr(&bind_addr), sizeof(bind_addr)) != 0) {
+        return -errno;
+    }
+
+    const struct sockaddr_nl kernel_addr = {
+            .nl_family = AF_NETLINK,
+            .nl_pad = 0,
+            .nl_pid = 0,
+            .nl_groups = groups,
+    };
+    if (connect(s.get(), asSockaddr(&kernel_addr), sizeof(kernel_addr)) != 0) {
+        return -errno;
+    }
+
+    return s.release();
+}
+
+int netlinkSocket(unsigned groups) {
+    return netlinkSocket(NETLINK_NETFILTER, groups);
+}
+
+// Check whether the specified interface is up.
+bool interfaceIsUp(const std::string name) {
+    struct ifreq ifr = {};
+    strlcpy(ifr.ifr_name, name.c_str(), sizeof(ifr.ifr_name));
+    int sock = socket(AF_INET6, SOCK_DGRAM, 0);
+    if (sock == -1) return false;
+    int ret = ioctl(sock, SIOCGIFFLAGS, &ifr, sizeof(ifr));
+    close(sock);
+    return (ret == 0) && (ifr.ifr_flags & IFF_UP);
+}
+
+// Callback class for both events and NAT timeout updates.
+class TetheringOffloadCallback : public BnTetheringOffloadCallback {
+  public:
+    ndk::ScopedAStatus onEvent(OffloadCallbackEvent in_event) override {
+        auto lock = std::lock_guard{mMutex};
+        mOnEventInvoked = true;
+        mLastEvent = in_event;
+        mNotifyCv.notify_all();
+        return ndk::ScopedAStatus::ok();
+    }
+
+    ndk::ScopedAStatus updateTimeout(const NatTimeoutUpdate& in_params) override {
+        auto lock = std::lock_guard{mMutex};
+        mOnUpdateTimeoutInvoked = true;
+        mNatTimeout = in_params;
+        mNotifyCv.notify_all();
+        return ndk::ScopedAStatus::ok();
+    }
+
+  private:
+    std::mutex mMutex;
+    std::condition_variable mNotifyCv;
+    OffloadCallbackEvent mLastEvent;
+    NatTimeoutUpdate mNatTimeout;
+    bool mOnEventInvoked = false;
+    bool mOnUpdateTimeoutInvoked = false;
+};
+
+// The common base class for tetheroffload AIDL HAL tests.
+class TetheroffloadAidlTestBase : public testing::TestWithParam<std::string> {
+  public:
+    virtual void SetUp() override { getService(); }
+    virtual void TearDown() override {
+        // For good measure, the teardown should try stopOffload() once more, since
+        // different HAL call test cycles might enter this function. Also the
+        // return code cannot be actually expected for all cases, hence ignore it.
+        stopOffload(ExpectBoolean::Ignored);
+    };
+
+  protected:
+    void getService() {
+        AIBinder* binder = AServiceManager_waitForService(GetParam().c_str());
+        ASSERT_NE(binder, nullptr);
+        mOffload = IOffload::fromBinder(ndk::SpAIBinder(binder));
+    }
+
+    void initOffload(const bool expectedResult) {
+        unique_fd ufd1(netlinkSocket(kFd1Groups));
+        if (ufd1.get() < 0) {
+            ALOGE("Unable to create conntrack sockets: %d/%s", errno, strerror(errno));
+            FAIL();
+        }
+        ndk::ScopedFileDescriptor fd1 = ndk::ScopedFileDescriptor(ufd1.release());
+
+        unique_fd ufd2(netlinkSocket(kFd2Groups));
+        if (ufd2.get() < 0) {
+            ALOGE("Unable to create conntrack sockets: %d/%s", errno, strerror(errno));
+            FAIL();
+        }
+        ndk::ScopedFileDescriptor fd2 = ndk::ScopedFileDescriptor(ufd2.release());
+
+        mTetheringOffloadCallback = ndk::SharedRefBase::make<TetheringOffloadCallback>();
+        ASSERT_NE(mTetheringOffloadCallback, nullptr) << "Could not get offload callback";
+
+        ASSERT_EQ(mOffload->initOffload(fd1, fd2, mTetheringOffloadCallback).getExceptionCode(),
+                  expectedResult ? EX_NONE : EX_ILLEGAL_STATE);
+    }
+
+    void stopOffload(const ExpectBoolean expectedResult) {
+        ndk::ScopedAStatus status = mOffload->stopOffload();
+        if (expectedResult == ExpectBoolean::Ignored) return;
+        ASSERT_EQ(status.getExceptionCode(),
+                  expectedResult == ExpectBoolean::True ? EX_NONE : EX_ILLEGAL_STATE);
+    }
+
+    std::shared_ptr<IOffload> mOffload;
+    std::shared_ptr<TetheringOffloadCallback> mTetheringOffloadCallback;
+};
+
+// The test class for tetheroffload before initialization.
+class TetheroffloadAidlPreInitTest : public TetheroffloadAidlTestBase {
+  public:
+    virtual void SetUp() override { getService(); }
+};
+
+// The main test class for tetheroffload AIDL HAL.
+class TetheroffloadAidlGeneralTest : public TetheroffloadAidlTestBase {
+  public:
+    virtual void SetUp() override {
+        getService();
+        initOffload(true);
+    }
+};
+
+// Passing invalid file descriptor to initOffload() should return an error.
+// Check that this occurs when both FDs are empty.
+TEST_P(TetheroffloadAidlPreInitTest, TestInitOffloadInvalidFdsReturnsError) {
+    ndk::ScopedFileDescriptor fd1 = ndk::ScopedFileDescriptor(-1);
+    ndk::ScopedFileDescriptor fd2 = ndk::ScopedFileDescriptor(-1);
+    mTetheringOffloadCallback = ndk::SharedRefBase::make<TetheringOffloadCallback>();
+    ASSERT_NE(mTetheringOffloadCallback, nullptr) << "Could not get offload callback";
+    EXPECT_THAT(mOffload->initOffload(fd1, fd2, mTetheringOffloadCallback).getExceptionCode(),
+                AnyOf(Eq(EX_ILLEGAL_ARGUMENT), Eq(EX_TRANSACTION_FAILED)));
+}
+
+// Passing invalid file descriptor to initOffload() should return an error.
+// Check that this occurs when FD1 is empty.
+TEST_P(TetheroffloadAidlPreInitTest, TestInitOffloadInvalidFd1ReturnsError) {
+    ndk::ScopedFileDescriptor fd1 = ndk::ScopedFileDescriptor(-1);
+    unique_fd ufd2(netlinkSocket(kFd2Groups));
+    if (ufd2.get() < 0) {
+        ALOGE("Unable to create conntrack sockets: %d/%s", errno, strerror(errno));
+        FAIL();
+    }
+    ndk::ScopedFileDescriptor fd2 = ndk::ScopedFileDescriptor(ufd2.release());
+    mTetheringOffloadCallback = ndk::SharedRefBase::make<TetheringOffloadCallback>();
+    ASSERT_NE(mTetheringOffloadCallback, nullptr) << "Could not get offload callback";
+    EXPECT_THAT(mOffload->initOffload(fd1, fd2, mTetheringOffloadCallback).getExceptionCode(),
+                AnyOf(Eq(EX_ILLEGAL_ARGUMENT), Eq(EX_TRANSACTION_FAILED)));
+}
+
+// Passing invalid file descriptor to initOffload() should return an error.
+// Check that this occurs when FD2 is empty.
+TEST_P(TetheroffloadAidlPreInitTest, TestInitOffloadInvalidFd2ReturnsError) {
+    unique_fd ufd1(netlinkSocket(kFd1Groups));
+    if (ufd1.get() < 0) {
+        ALOGE("Unable to create conntrack sockets: %d/%s", errno, strerror(errno));
+        FAIL();
+    }
+    ndk::ScopedFileDescriptor fd1 = ndk::ScopedFileDescriptor(ufd1.release());
+    ndk::ScopedFileDescriptor fd2 = ndk::ScopedFileDescriptor(-1);
+    mTetheringOffloadCallback = ndk::SharedRefBase::make<TetheringOffloadCallback>();
+    ASSERT_NE(mTetheringOffloadCallback, nullptr) << "Could not get offload callback";
+    EXPECT_THAT(mOffload->initOffload(fd1, fd2, mTetheringOffloadCallback).getExceptionCode(),
+                AnyOf(Eq(EX_ILLEGAL_ARGUMENT), Eq(EX_TRANSACTION_FAILED)));
+}
+
+// Call initOffload() multiple times. Check that non-first initOffload() calls return error.
+TEST_P(TetheroffloadAidlPreInitTest, AdditionalInitsWithoutStopReturnError) {
+    initOffload(true);
+    initOffload(false);
+    initOffload(false);
+    initOffload(false);
+}
+
+// Check that calling stopOffload() without first having called initOffload() returns error.
+TEST_P(TetheroffloadAidlPreInitTest, MultipleStopsWithoutInitReturnError) {
+    stopOffload(ExpectBoolean::False);
+    stopOffload(ExpectBoolean::False);
+    stopOffload(ExpectBoolean::False);
+}
+
+// Check that calling stopOffload() after a complete init/stop cycle returns error.
+TEST_P(TetheroffloadAidlPreInitTest, AdditionalStopsWithInitReturnError) {
+    initOffload(true);
+    // Call setUpstreamParameters() so that "offload" can be reasonably said
+    // to be both requested and operational.
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("192.0.0.2");
+    const std::string v4Gw("192.0.0.1");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1"), std::string("fe80::db8:2")};
+    EXPECT_TRUE(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).isOk());
+    if (!interfaceIsUp(TEST_IFACE)) {
+        return;
+    }
+    SCOPED_TRACE("Expecting stopOffload to succeed");
+    stopOffload(ExpectBoolean::True);  // balance out initOffload(true)
+    SCOPED_TRACE("Expecting stopOffload to fail the first time");
+    stopOffload(ExpectBoolean::False);
+    SCOPED_TRACE("Expecting stopOffload to fail the second time");
+    stopOffload(ExpectBoolean::False);
+}
+
+// Check that calling setLocalPrefixes() without first having called initOffload() returns error.
+TEST_P(TetheroffloadAidlPreInitTest, SetLocalPrefixesWithoutInitReturnsError) {
+    const std::vector<std::string> prefixes{std::string("2001:db8::/64")};
+    EXPECT_EQ(mOffload->setLocalPrefixes(prefixes).getExceptionCode(), EX_ILLEGAL_STATE);
+}
+
+// Check that calling getForwardedStats() without first having called initOffload()
+// returns zero bytes statistics.
+TEST_P(TetheroffloadAidlPreInitTest, GetForwardedStatsWithoutInitReturnsZeroValues) {
+    const std::string upstream(TEST_IFACE);
+    ForwardedStats stats;
+    EXPECT_TRUE(mOffload->getForwardedStats(upstream, &stats).isOk());
+    EXPECT_EQ(stats.rxBytes, 0ULL);
+    EXPECT_EQ(stats.txBytes, 0ULL);
+}
+
+// Check that calling setDataWarningAndLimit() without first having called initOffload() returns
+// error.
+TEST_P(TetheroffloadAidlPreInitTest, SetDataWarningAndLimitWithoutInitReturnsError) {
+    const std::string upstream(TEST_IFACE);
+    const int64_t warning = 5000LL;
+    const int64_t limit = 5000LL;
+    EXPECT_EQ(mOffload->setDataWarningAndLimit(upstream, warning, limit).getExceptionCode(),
+              EX_ILLEGAL_STATE);
+}
+
+// Check that calling setUpstreamParameters() without first having called initOffload()
+// returns error.
+TEST_P(TetheroffloadAidlPreInitTest, SetUpstreamParametersWithoutInitReturnsError) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("192.0.2.0/24");
+    const std::string v4Gw("192.0.2.1");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1")};
+    EXPECT_EQ(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).getExceptionCode(),
+              EX_ILLEGAL_STATE);
+}
+
+// Check that calling addDownstream() with an IPv4 prefix without first having called
+// initOffload() returns error.
+TEST_P(TetheroffloadAidlPreInitTest, AddIPv4DownstreamWithoutInitReturnsError) {
+    const std::string iface(TEST_IFACE);
+    const std::string prefix("192.0.2.0/24");
+    EXPECT_EQ(mOffload->addDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_STATE);
+}
+
+// Check that calling addDownstream() with an IPv6 prefix without first having called
+// initOffload() returns error.
+TEST_P(TetheroffloadAidlPreInitTest, AddIPv6DownstreamWithoutInitReturnsError) {
+    const std::string iface(TEST_IFACE);
+    const std::string prefix("2001:db8::/64");
+    EXPECT_EQ(mOffload->addDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_STATE);
+}
+
+// Check that calling removeDownstream() with an IPv4 prefix without first having called
+// initOffload() returns error.
+TEST_P(TetheroffloadAidlPreInitTest, RemoveIPv4DownstreamWithoutInitReturnsError) {
+    const std::string iface(TEST_IFACE);
+    const std::string prefix("192.0.2.0/24");
+    EXPECT_EQ(mOffload->removeDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_STATE);
+}
+
+// Check that calling removeDownstream() with an IPv6 prefix without first having called
+// initOffload() returns error.
+TEST_P(TetheroffloadAidlPreInitTest, RemoveIPv6DownstreamWithoutInitReturnsError) {
+    const std::string iface(TEST_IFACE);
+    const std::string prefix("2001:db8::/64");
+    EXPECT_EQ(mOffload->removeDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_STATE);
+}
+
+/*
+ * Tests for IOffload::setLocalPrefixes().
+ */
+
+// Test setLocalPrefixes() rejects an IPv4 address.
+TEST_P(TetheroffloadAidlGeneralTest, SetLocalPrefixesIPv4AddressFails) {
+    const std::vector<std::string> prefixes{std::string("192.0.2.1")};
+    EXPECT_EQ(mOffload->setLocalPrefixes(prefixes).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+}
+
+// Test setLocalPrefixes() rejects an IPv6 address.
+TEST_P(TetheroffloadAidlGeneralTest, SetLocalPrefixesIPv6AddressFails) {
+    const std::vector<std::string> prefixes{std::string("fe80::1")};
+    EXPECT_EQ(mOffload->setLocalPrefixes(prefixes).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+}
+
+// Test setLocalPrefixes() accepts both IPv4 and IPv6 prefixes.
+TEST_P(TetheroffloadAidlGeneralTest, SetLocalPrefixesIPv4v6PrefixesOk) {
+    const std::vector<std::string> prefixes{std::string("192.0.2.0/24"), std::string("fe80::/64")};
+    EXPECT_TRUE(mOffload->setLocalPrefixes(prefixes).isOk());
+}
+
+// Test that setLocalPrefixes() fails given empty input. There is always
+// a non-empty set of local prefixes; when all networking interfaces are down
+// we still apply {127.0.0.0/8, ::1/128, fe80::/64} here.
+TEST_P(TetheroffloadAidlGeneralTest, SetLocalPrefixesEmptyFails) {
+    const std::vector<std::string> prefixes{};
+    EXPECT_EQ(mOffload->setLocalPrefixes(prefixes).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+}
+
+// Test setLocalPrefixes() fails on incorrectly formed input strings.
+TEST_P(TetheroffloadAidlGeneralTest, SetLocalPrefixesInvalidFails) {
+    const std::vector<std::string> prefixes{std::string("192.0.2.0/24"), std::string("invalid")};
+    EXPECT_EQ(mOffload->setLocalPrefixes(prefixes).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+}
+
+/*
+ * Tests for IOffload::getForwardedStats().
+ */
+
+// Test that getForwardedStats() for a non-existent upstream yields zero bytes statistics.
+TEST_P(TetheroffloadAidlGeneralTest, GetForwardedStatsInvalidUpstreamIface) {
+    const std::string upstream("invalid");
+    ForwardedStats stats;
+    EXPECT_TRUE(mOffload->getForwardedStats(upstream, &stats).isOk());
+    EXPECT_EQ(stats.rxBytes, 0ULL);
+    EXPECT_EQ(stats.txBytes, 0ULL);
+}
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, GetForwardedStatsDummyIface) {
+    const std::string upstream(TEST_IFACE);
+    ForwardedStats stats;
+    EXPECT_TRUE(mOffload->getForwardedStats(upstream, &stats).isOk());
+    EXPECT_EQ(stats.rxBytes, 0ULL);
+    EXPECT_EQ(stats.txBytes, 0ULL);
+}
+
+/*
+ * Tests for IOffload::setDataWarningAndLimit().
+ */
+
+// Test that setDataWarningAndLimit() for an empty interface name fails.
+TEST_P(TetheroffloadAidlGeneralTest, SetDataWarningAndLimitEmptyUpstreamIfaceFails) {
+    const std::string upstream("");
+    const int64_t warning = 12345LL;
+    const int64_t limit = 67890LL;
+    EXPECT_THAT(mOffload->setDataWarningAndLimit(upstream, warning, limit).getExceptionCode(),
+                AnyOf(Eq(EX_ILLEGAL_ARGUMENT), Eq(EX_UNSUPPORTED_OPERATION)));
+}
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, SetDataWarningAndLimitNonZeroOk) {
+    const std::string upstream(TEST_IFACE);
+    const int64_t warning = 4000LL;
+    const int64_t limit = 5000LL;
+    EXPECT_THAT(mOffload->setDataWarningAndLimit(upstream, warning, limit).getExceptionCode(),
+                AnyOf(Eq(EX_NONE), Eq(EX_UNSUPPORTED_OPERATION)));
+}
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, SetDataWarningAndLimitZeroOk) {
+    const std::string upstream(TEST_IFACE);
+    const int64_t warning = 0LL;
+    const int64_t limit = 0LL;
+    EXPECT_THAT(mOffload->setDataWarningAndLimit(upstream, warning, limit).getExceptionCode(),
+                AnyOf(Eq(EX_NONE), Eq(EX_UNSUPPORTED_OPERATION)));
+}
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, SetDataWarningAndLimitUnlimitedWarningOk) {
+    const std::string upstream(TEST_IFACE);
+    const int64_t warning = LLONG_MAX;
+    const int64_t limit = 5000LL;
+    EXPECT_TRUE(mOffload->setDataWarningAndLimit(upstream, warning, limit).isOk());
+}
+
+// Test that setDataWarningAndLimit() with negative thresholds fails.
+TEST_P(TetheroffloadAidlGeneralTest, SetDataWarningAndLimitNegativeFails) {
+    const std::string upstream(TEST_IFACE);
+    const int64_t warning = -1LL;
+    const int64_t limit = -1LL;
+    EXPECT_THAT(mOffload->setDataWarningAndLimit(upstream, warning, limit).getExceptionCode(),
+                AnyOf(Eq(EX_ILLEGAL_ARGUMENT), Eq(EX_UNSUPPORTED_OPERATION)));
+}
+
+/*
+ * Tests for IOffload::setUpstreamParameters().
+ */
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersIPv6OnlyOk) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("");
+    const std::string v4Gw("");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1"), std::string("fe80::db8:2")};
+    EXPECT_TRUE(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).isOk());
+}
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersAlternateIPv6OnlyOk) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("");
+    const std::string v4Gw("");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1"), std::string("fe80::db8:3")};
+    EXPECT_TRUE(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).isOk());
+}
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersIPv4OnlyOk) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("192.0.2.2");
+    const std::string v4Gw("192.0.2.1");
+    const std::vector<std::string> v6Gws{};
+    EXPECT_TRUE(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).isOk());
+}
+
+// TEST_IFACE is presumed to exist on the device and be up. No packets
+// are ever actually caused to be forwarded.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersIPv4v6Ok) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("192.0.2.2");
+    const std::string v4Gw("192.0.2.1");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1"), std::string("fe80::db8:2")};
+    EXPECT_TRUE(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).isOk());
+}
+
+// Test that setUpstreamParameters() fails when all parameters are empty.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersEmptyFails) {
+    const std::string iface("");
+    const std::string v4Addr("");
+    const std::string v4Gw("");
+    const std::vector<std::string> v6Gws{};
+    EXPECT_EQ(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).getExceptionCode(),
+              EX_ILLEGAL_ARGUMENT);
+}
+
+// Test that setUpstreamParameters() fails when given empty or non-existent interface names.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersBogusIfaceFails) {
+    const std::string v4Addr("192.0.2.2");
+    const std::string v4Gw("192.0.2.1");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1")};
+    for (const auto& bogus : {"", "invalid"}) {
+        SCOPED_TRACE(testing::Message() << "upstream: " << bogus);
+        const std::string iface(bogus);
+        EXPECT_EQ(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).getExceptionCode(),
+                  EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+// Test that setUpstreamParameters() fails when given unparseable IPv4 addresses.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersInvalidIPv4AddrFails) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Gw("192.0.2.1");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1")};
+    for (const auto& bogus : {"invalid", "192.0.2"}) {
+        SCOPED_TRACE(testing::Message() << "v4addr: " << bogus);
+        const std::string v4Addr(bogus);
+        EXPECT_EQ(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).getExceptionCode(),
+                  EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+// Test that setUpstreamParameters() fails when given unparseable IPv4 gateways.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersInvalidIPv4GatewayFails) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("192.0.2.2");
+    const std::vector<std::string> v6Gws{std::string("fe80::db8:1")};
+    for (const auto& bogus : {"invalid", "192.0.2"}) {
+        SCOPED_TRACE(testing::Message() << "v4gateway: " << bogus);
+        const std::string v4Gw(bogus);
+        EXPECT_EQ(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).getExceptionCode(),
+                  EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+// Test that setUpstreamParameters() fails when given unparseable IPv6 gateways.
+TEST_P(TetheroffloadAidlGeneralTest, SetUpstreamParametersBadIPv6GatewaysFail) {
+    const std::string iface(TEST_IFACE);
+    const std::string v4Addr("192.0.2.2");
+    const std::string v4Gw("192.0.2.1");
+    for (const auto& bogus : {"", "invalid", "fe80::bogus", "192.0.2.66"}) {
+        SCOPED_TRACE(testing::Message() << "v6gateway: " << bogus);
+        const std::vector<std::string> v6Gws{std::string("fe80::1"), std::string(bogus)};
+        EXPECT_EQ(mOffload->setUpstreamParameters(iface, v4Addr, v4Gw, v6Gws).getExceptionCode(),
+                  EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+/*
+ * Tests for IOffload::addDownstream().
+ */
+
+// Test addDownstream() works given an IPv4 prefix.
+TEST_P(TetheroffloadAidlGeneralTest, AddDownstreamIPv4) {
+    const std::string iface("dummy0");
+    const std::string prefix("192.0.2.0/24");
+    EXPECT_TRUE(mOffload->addDownstream(iface, prefix).isOk());
+}
+
+// Test addDownstream() works given an IPv6 prefix.
+TEST_P(TetheroffloadAidlGeneralTest, AddDownstreamIPv6) {
+    const std::string iface("dummy0");
+    const std::string prefix("2001:db8::/64");
+    EXPECT_TRUE(mOffload->addDownstream(iface, prefix).isOk());
+}
+
+// Test addDownstream() fails given all empty parameters.
+TEST_P(TetheroffloadAidlGeneralTest, AddDownstreamEmptyFails) {
+    const std::string iface("");
+    const std::string prefix("");
+    EXPECT_EQ(mOffload->addDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+}
+
+// Test addDownstream() fails given empty or non-existent interface names.
+TEST_P(TetheroffloadAidlGeneralTest, AddDownstreamInvalidIfaceFails) {
+    const std::string prefix("192.0.2.0/24");
+    for (const auto& bogus : {"", "invalid"}) {
+        SCOPED_TRACE(testing::Message() << "iface: " << bogus);
+        const std::string iface(bogus);
+        EXPECT_EQ(mOffload->addDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+// Test addDownstream() fails given unparseable prefix arguments.
+TEST_P(TetheroffloadAidlGeneralTest, AddDownstreamBogusPrefixFails) {
+    const std::string iface("dummy0");
+    for (const auto& bogus : {"", "192.0.2/24", "2001:db8/64"}) {
+        SCOPED_TRACE(testing::Message() << "prefix: " << bogus);
+        const std::string prefix(bogus);
+        EXPECT_EQ(mOffload->addDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+/*
+ * Tests for IOffload::removeDownstream().
+ */
+
+// Test removeDownstream() works given an IPv4 prefix.
+TEST_P(TetheroffloadAidlGeneralTest, RemoveDownstreamIPv4) {
+    const std::string iface("dummy0");
+    const std::string prefix("192.0.2.0/24");
+    // First add the downstream, otherwise removeDownstream logic can reasonably
+    // return error for downstreams not previously added.
+    EXPECT_TRUE(mOffload->addDownstream(iface, prefix).isOk());
+    EXPECT_TRUE(mOffload->removeDownstream(iface, prefix).isOk());
+}
+
+// Test removeDownstream() works given an IPv6 prefix.
+TEST_P(TetheroffloadAidlGeneralTest, RemoveDownstreamIPv6) {
+    const std::string iface("dummy0");
+    const std::string prefix("2001:db8::/64");
+    // First add the downstream, otherwise removeDownstream logic can reasonably
+    // return error for downstreams not previously added.
+    EXPECT_TRUE(mOffload->addDownstream(iface, prefix).isOk());
+    EXPECT_TRUE(mOffload->removeDownstream(iface, prefix).isOk());
+}
+
+// Test removeDownstream() fails given all empty parameters.
+TEST_P(TetheroffloadAidlGeneralTest, RemoveDownstreamEmptyFails) {
+    const std::string iface("");
+    const std::string prefix("");
+    EXPECT_EQ(mOffload->removeDownstream(iface, prefix).getExceptionCode(), EX_ILLEGAL_ARGUMENT);
+}
+
+// Test removeDownstream() fails given empty or non-existent interface names.
+TEST_P(TetheroffloadAidlGeneralTest, RemoveDownstreamBogusIfaceFails) {
+    const std::string prefix("192.0.2.0/24");
+    for (const auto& bogus : {"", "invalid"}) {
+        SCOPED_TRACE(testing::Message() << "iface: " << bogus);
+        const std::string iface(bogus);
+        EXPECT_EQ(mOffload->removeDownstream(iface, prefix).getExceptionCode(),
+                  EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+// Test removeDownstream() fails given unparseable prefix arguments.
+TEST_P(TetheroffloadAidlGeneralTest, RemoveDownstreamBogusPrefixFails) {
+    const std::string iface("dummy0");
+    for (const auto& bogus : {"", "192.0.2/24", "2001:db8/64"}) {
+        SCOPED_TRACE(testing::Message() << "prefix: " << bogus);
+        const std::string prefix(bogus);
+        EXPECT_EQ(mOffload->removeDownstream(iface, prefix).getExceptionCode(),
+                  EX_ILLEGAL_ARGUMENT);
+    }
+}
+
+GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(TetheroffloadAidlTestBase);
+INSTANTIATE_TEST_SUITE_P(
+        IOffload, TetheroffloadAidlTestBase,
+        testing::ValuesIn(::android::getAidlHalInstanceNames(IOffload::descriptor)),
+        ::android::PrintInstanceNameToString);
+
+GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(TetheroffloadAidlPreInitTest);
+INSTANTIATE_TEST_SUITE_P(
+        IOffload, TetheroffloadAidlPreInitTest,
+        testing::ValuesIn(::android::getAidlHalInstanceNames(IOffload::descriptor)),
+        ::android::PrintInstanceNameToString);
+
+GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(TetheroffloadAidlGeneralTest);
+INSTANTIATE_TEST_SUITE_P(
+        IOffload, TetheroffloadAidlGeneralTest,
+        testing::ValuesIn(::android::getAidlHalInstanceNames(IOffload::descriptor)),
+        ::android::PrintInstanceNameToString);
+
+}  // namespace
+
+int main(int argc, char** argv) {
+    ::testing::InitGoogleTest(&argc, argv);
+    ABinderProcess_setThreadPoolMaxThreadCount(1);
+    ABinderProcess_startThreadPool();
+    return RUN_ALL_TESTS();
+}
+
+}  // namespace aidl::android::hardware::tetheroffload