diff --git a/wifi/1.0/default/hidl_return_util.h b/wifi/1.0/default/hidl_return_util.h
new file mode 100644
index 0000000..2986165
--- /dev/null
+++ b/wifi/1.0/default/hidl_return_util.h
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#ifndef HIDL_RETURN_UTIL_H_
+#define HIDL_RETURN_UTIL_H_
+
+#include "wifi_status_util.h"
+
+namespace android {
+namespace hardware {
+namespace wifi {
+namespace V1_0 {
+namespace implementation {
+namespace hidl_return_util {
+
+/**
+ * These utility functions are used to invoke a method on the provided
+ * HIDL interface object.
+ * These functions checks if the provided HIDL interface object is valid.
+ * a) if valid, Invokes the corresponding internal implementation function of
+ * the HIDL method. It then invokes the HIDL continuation callback with
+ * the status and any returned values.
+ * b) if invalid, invokes the HIDL continuation callback with the
+ * provided error status and default values.
+ */
+// Use for HIDL methods which return only an instance of WifiStatus.
+template <typename ObjT, typename WorkFuncT, typename... Args>
+Return<void> validateAndCall(
+    ObjT* obj,
+    WifiStatusCode status_code_if_invalid,
+    WorkFuncT&& work,
+    const std::function<void(const WifiStatus&)>& hidl_cb,
+    Args&&... args) {
+  if (obj->isValid()) {
+    hidl_cb((obj->*work)(std::forward<Args>(args)...));
+  } else {
+    hidl_cb(createWifiStatus(status_code_if_invalid));
+  }
+  return Void();
+}
+
+// Use for HIDL methods which return instance of WifiStatus and a single return
+// value.
+template <typename ObjT, typename WorkFuncT, typename ReturnT, typename... Args>
+Return<void> validateAndCall(
+    ObjT* obj,
+    WifiStatusCode status_code_if_invalid,
+    WorkFuncT&& work,
+    const std::function<void(const WifiStatus&, ReturnT)>& hidl_cb,
+    Args&&... args) {
+  if (obj->isValid()) {
+    const auto& ret_pair = (obj->*work)(std::forward<Args>(args)...);
+    const WifiStatus& status = std::get<0>(ret_pair);
+    const auto& ret_value = std::get<1>(ret_pair);
+    hidl_cb(status, ret_value);
+  } else {
+    hidl_cb(createWifiStatus(status_code_if_invalid),
+            typename std::remove_reference<ReturnT>::type());
+  }
+  return Void();
+}
+
+// Use for HIDL methods which return instance of WifiStatus and 2 return
+// values.
+template <typename ObjT,
+          typename WorkFuncT,
+          typename ReturnT1,
+          typename ReturnT2,
+          typename... Args>
+Return<void> validateAndCall(
+    ObjT* obj,
+    WifiStatusCode status_code_if_invalid,
+    WorkFuncT&& work,
+    const std::function<void(const WifiStatus&, ReturnT1, ReturnT2)>& hidl_cb,
+    Args&&... args) {
+  if (obj->isValid()) {
+    const auto& ret_tuple = (obj->*work)(std::forward<Args>(args)...);
+    const WifiStatus& status = std::get<0>(ret_tuple);
+    const auto& ret_value1 = std::get<1>(ret_tuple);
+    const auto& ret_value2 = std::get<2>(ret_tuple);
+    hidl_cb(status, ret_value1, ret_value2);
+  } else {
+    hidl_cb(createWifiStatus(status_code_if_invalid),
+            typename std::remove_reference<ReturnT1>::type(),
+            typename std::remove_reference<ReturnT2>::type());
+  }
+  return Void();
+}
+
+}  // namespace hidl_util
+}  // namespace implementation
+}  // namespace V1_0
+}  // namespace wifi
+}  // namespace hardware
+}  // namespace android
+#endif  // HIDL_RETURN_UTIL_H_
diff --git a/wifi/1.0/default/wifi.cpp b/wifi/1.0/default/wifi.cpp
index e10826b..73b921a 100644
--- a/wifi/1.0/default/wifi.cpp
+++ b/wifi/1.0/default/wifi.cpp
@@ -14,11 +14,10 @@
  * limitations under the License.
  */
 
-#include "wifi.h"
-
 #include <android-base/logging.h>
 
-#include "wifi_chip.h"
+#include "hidl_return_util.h"
+#include "wifi.h"
 #include "wifi_status_util.h"
 
 namespace {
@@ -31,15 +30,24 @@
 namespace wifi {
 namespace V1_0 {
 namespace implementation {
+using hidl_return_util::validateAndCall;
 
 Wifi::Wifi()
     : legacy_hal_(new WifiLegacyHal()), run_state_(RunState::STOPPED) {}
 
+bool Wifi::isValid() {
+  // This object is always valid.
+  return true;
+}
+
 Return<void> Wifi::registerEventCallback(
-    const sp<IWifiEventCallback>& event_callback) {
-  // TODO(b/31632518): remove the callback when the client is destroyed
-  event_callbacks_.emplace_back(event_callback);
-  return Void();
+    const sp<IWifiEventCallback>& event_callback,
+    registerEventCallback_cb hidl_status_cb) {
+  return validateAndCall(this,
+                         WifiStatusCode::ERROR_UNKNOWN,
+                         &Wifi::registerEventCallbackInternal,
+                         hidl_status_cb,
+                         event_callback);
 }
 
 Return<bool> Wifi::isStarted() {
@@ -47,22 +55,53 @@
 }
 
 Return<void> Wifi::start(start_cb hidl_status_cb) {
+  return validateAndCall(this,
+                         WifiStatusCode::ERROR_UNKNOWN,
+                         &Wifi::startInternal,
+                         hidl_status_cb);
+}
+
+Return<void> Wifi::stop(stop_cb hidl_status_cb) {
+  return validateAndCall(
+      this, WifiStatusCode::ERROR_UNKNOWN, &Wifi::stopInternal, hidl_status_cb);
+}
+
+Return<void> Wifi::getChipIds(getChipIds_cb hidl_status_cb) {
+  return validateAndCall(this,
+                         WifiStatusCode::ERROR_UNKNOWN,
+                         &Wifi::getChipIdsInternal,
+                         hidl_status_cb);
+}
+
+Return<void> Wifi::getChip(ChipId chip_id, getChip_cb hidl_status_cb) {
+  return validateAndCall(this,
+                         WifiStatusCode::ERROR_UNKNOWN,
+                         &Wifi::getChipInternal,
+                         hidl_status_cb,
+                         chip_id);
+}
+
+WifiStatus Wifi::registerEventCallbackInternal(
+    const sp<IWifiEventCallback>& event_callback) {
+  // TODO(b/31632518): remove the callback when the client is destroyed
+  event_callbacks_.emplace_back(event_callback);
+  return createWifiStatus(WifiStatusCode::SUCCESS);
+}
+
+WifiStatus Wifi::startInternal() {
   if (run_state_ == RunState::STARTED) {
-    hidl_status_cb(createWifiStatus(WifiStatusCode::SUCCESS));
-    return Void();
+    return createWifiStatus(WifiStatusCode::SUCCESS);
   } else if (run_state_ == RunState::STOPPING) {
-    hidl_status_cb(createWifiStatus(WifiStatusCode::ERROR_NOT_AVAILABLE,
-                                    "HAL is stopping"));
-    return Void();
+    return createWifiStatus(WifiStatusCode::ERROR_NOT_AVAILABLE,
+                            "HAL is stopping");
   }
 
   LOG(INFO) << "Starting HAL";
   wifi_error legacy_status = legacy_hal_->start();
   if (legacy_status != WIFI_SUCCESS) {
     LOG(ERROR) << "Failed to start Wifi HAL";
-    hidl_status_cb(
-        createWifiStatusFromLegacyError(legacy_status, "Failed to start HAL"));
-    return Void();
+    return createWifiStatusFromLegacyError(legacy_status,
+                                           "Failed to start HAL");
   }
 
   // Create the chip instance once the HAL is started.
@@ -73,18 +112,15 @@
       LOG(ERROR) << "Failed to invoke onStart callback";
     };
   }
-  hidl_status_cb(createWifiStatus(WifiStatusCode::SUCCESS));
-  return Void();
+  return createWifiStatus(WifiStatusCode::SUCCESS);
 }
 
-Return<void> Wifi::stop(stop_cb hidl_status_cb) {
+WifiStatus Wifi::stopInternal() {
   if (run_state_ == RunState::STOPPED) {
-    hidl_status_cb(createWifiStatus(WifiStatusCode::SUCCESS));
-    return Void();
+    return createWifiStatus(WifiStatusCode::SUCCESS);
   } else if (run_state_ == RunState::STOPPING) {
-    hidl_status_cb(createWifiStatus(WifiStatusCode::ERROR_NOT_AVAILABLE,
-                                    "HAL is stopping"));
-    return Void();
+    return createWifiStatus(WifiStatusCode::ERROR_NOT_AVAILABLE,
+                            "HAL is stopping");
   }
 
   LOG(INFO) << "Stopping HAL";
@@ -109,33 +145,28 @@
     for (const auto& callback : event_callbacks_) {
       callback->onFailure(wifi_status);
     }
-    hidl_status_cb(wifi_status);
-    return Void();
+    return wifi_status;
   }
-  hidl_status_cb(createWifiStatus(WifiStatusCode::SUCCESS));
-  return Void();
+  return createWifiStatus(WifiStatusCode::SUCCESS);
 }
 
-Return<void> Wifi::getChipIds(getChipIds_cb hidl_status_cb) {
+std::pair<WifiStatus, std::vector<ChipId>> Wifi::getChipIdsInternal() {
   std::vector<ChipId> chip_ids;
   if (chip_.get()) {
     chip_ids.emplace_back(kChipId);
   }
-  hidl_vec<ChipId> hidl_data;
-  hidl_data.setToExternal(chip_ids.data(), chip_ids.size());
-  hidl_status_cb(hidl_data);
-  return Void();
+  return {createWifiStatus(WifiStatusCode::SUCCESS), std::move(chip_ids)};
 }
 
-Return<void> Wifi::getChip(ChipId chip_id, getChip_cb hidl_status_cb) {
-  if (chip_.get() && chip_id == kChipId) {
-    hidl_status_cb(chip_);
-  } else {
-    hidl_status_cb(nullptr);
+std::pair<WifiStatus, sp<IWifiChip>> Wifi::getChipInternal(ChipId chip_id) {
+  if (!chip_.get()) {
+    return {createWifiStatus(WifiStatusCode::ERROR_NOT_STARTED), nullptr};
   }
-  return Void();
+  if (chip_id != kChipId) {
+    return {createWifiStatus(WifiStatusCode::ERROR_INVALID_ARGS), nullptr};
+  }
+  return {createWifiStatus(WifiStatusCode::SUCCESS), chip_};
 }
-
 }  // namespace implementation
 }  // namespace V1_0
 }  // namespace wifi
diff --git a/wifi/1.0/default/wifi.h b/wifi/1.0/default/wifi.h
index 989b630..c682116 100644
--- a/wifi/1.0/default/wifi.h
+++ b/wifi/1.0/default/wifi.h
@@ -39,9 +39,12 @@
  public:
   Wifi();
 
+  bool isValid();
+
   // HIDL methods exposed.
   Return<void> registerEventCallback(
-      const sp<IWifiEventCallback>& event_callback) override;
+      const sp<IWifiEventCallback>& event_callback,
+      registerEventCallback_cb hidl_status_cb) override;
   Return<bool> isStarted() override;
   Return<void> start(start_cb hidl_status_cb) override;
   Return<void> stop(stop_cb hidl_status_cb) override;
@@ -51,6 +54,14 @@
  private:
   enum class RunState { STOPPED, STARTED, STOPPING };
 
+  // Corresponding worker functions for the HIDL methods.
+  WifiStatus registerEventCallbackInternal(
+      const sp<IWifiEventCallback>& event_callback);
+  WifiStatus startInternal();
+  WifiStatus stopInternal();
+  std::pair<WifiStatus, std::vector<ChipId>> getChipIdsInternal();
+  std::pair<WifiStatus, sp<IWifiChip>> getChipInternal(ChipId chip_id);
+
   // Instance is created in this root level |IWifi| HIDL interface object
   // and shared with all the child HIDL interface objects.
   std::shared_ptr<WifiLegacyHal> legacy_hal_;
diff --git a/wifi/1.0/default/wifi_status_util.cpp b/wifi/1.0/default/wifi_status_util.cpp
index 21b4eeb..34a1c1d 100644
--- a/wifi/1.0/default/wifi_status_util.cpp
+++ b/wifi/1.0/default/wifi_status_util.cpp
@@ -50,10 +50,7 @@
 
 WifiStatus createWifiStatus(WifiStatusCode code,
                             const std::string& description) {
-  WifiStatus result;
-  result.code = code;
-  result.description = description.data();
-  return result;
+  return {code, description};
 }
 
 WifiStatus createWifiStatus(WifiStatusCode code) {