Get the pal event handler from pal gattclient

features/FEATURE_BLE/ble/pal/PalGattClient.h

@@ -601,8 +601,27 @@ public:
          _transaction_timeout_cb = cb;
      }
 
+     /**
+      * Sets the event handler that us called by the PAL porters to notify the stack of events
+      * which will in turn be passed onto the user application when appropriate.
+      *
+      * @param event_handler The new event handler interface implementation.
+      */
+     void set_event_handler(EventHandler* event_handler) {
+         _event_handler = event_handler;
+     }
+
+     /**
+      * Get the currently registered event handler.
+      *
+      * @return Currently registered event handler. NULL if no event handler is present.
+      */
+     EventHandler* get_event_handler() {
+         return _event_handler;
+     }
+
 protected:
-    GattClient() { }
+    GattClient() : _event_handler(NULL) { }
 
     virtual ~GattClient() { }
 
@@ -640,6 +659,8 @@ protected:
     }
 
 private:
+    EventHandler* _event_handler;
+
     /**
      * Callback called when the client receive a message from the server.
      */

features/FEATURE_BLE/targets/TARGET_CORDIO/CordioBLE.h

@@ -107,6 +107,13 @@ public:
      */
     virtual generic::GenericGattClient &getGattClient();
 
+    /**
+     * Get the PAL Gatt Client.
+     *
+     * @return PAL Gatt Client.
+     */
+    pal::AttClientToGattClientAdapter &BLE::getPalGattClient();
+
     /**
      * @see BLEInstanceBase::getSecurityManager
      */

features/FEATURE_BLE/targets/TARGET_CORDIO/CordioPalAttClient.cpp

@@ -26,8 +26,10 @@ void CordioAttClient::att_client_handler(const attEvt_t* event)
 {
     if (event->hdr.status == ATT_SUCCESS && event->hdr.event == ATT_MTU_UPDATE_IND) {
         ble::vendor::cordio::BLE& ble = ble::vendor::cordio::BLE::deviceInstance();
-        ble::pal::GattClient::EventHandler &handler = ble.getGattClient();
-        handler.on_att_mtu_change(event->hdr.param, event->mtu);
+        ble::pal::GattClient::EventHandler *handler = ble.getPalGattClient().get_event_handler();
+        if (handler) {
+            handler->on_att_mtu_change(event->hdr.param, event->mtu);
+        }
     } else {
         // all handlers are stored in a static array
         static const event_handler_t handlers[] = {

features/FEATURE_BLE/targets/TARGET_CORDIO/source/CordioBLE.cpp

@@ -199,13 +199,19 @@ const GattServer& BLE::getGattServer() const
 }
 
 generic::GenericGattClient& BLE::getGattClient()
+{
+    static generic::GenericGattClient gatt_client(&getPalGattClient());
+
+    return gatt_client;
+}
+
+pal::AttClientToGattClientAdapter& BLE::getPalGattClient()
 {
     static pal::AttClientToGattClientAdapter pal_client(
         pal::vendor::cordio::CordioAttClient::get_client()
     );
-    static generic::GenericGattClient client(&pal_client);
 
-    return client;
+    return pal_client;
 }
 
 SecurityManager& BLE::getSecurityManager()