Function IoTHubModuleClient_SetInputMessageCallback 

pub unsafe extern "C" fn IoTHubModuleClient_SetInputMessageCallback(
    iotHubModuleClientHandle: IOTHUB_MODULE_CLIENT_HANDLE,
    inputName: *const c_char,
    eventHandlerCallback: IOTHUB_CLIENT_MESSAGE_CALLBACK_ASYNC,
    userContextCallback: *mut c_void,
) -> IOTHUB_CLIENT_RESULT

@brief This API sets callback for method call that is directed to specified ‘inputName’ queue (e.g. messages from IoTHubModuleClient_SendEventToOutputAsync)

@param iotHubModuleClientHandle The handle created by a call to the create function. @param inputName The name of the queue to listen on for this moduleMethodCallback/userContextCallback. @param eventHandlerCallback The callback which will be called by IoT Hub. @param userContextCallback User specified context that will be provided to the callback. This can be @c NULL.

@return IOTHUB_CLIENT_OK upon success or an error code upon failure.