public static extern CURLcode RegisterDebugCallback( SafeCurlHandle curl, DebugCallback callback, IntPtr userPointer, ref SafeCallbackHandle callbackHandle);
public static extern void RegisterSeekCallback( SafeCurlHandle curl, SeekCallback callback, IntPtr userPointer, ref SafeCallbackHandle callbackHandle);
public static extern void RegisterReadWriteCallback( SafeCurlHandle curl, ReadWriteFunction functionType, ReadWriteCallback callback, IntPtr userPointer, ref SafeCallbackHandle callbackHandle);
public static extern CURLcode RegisterSslCtxCallback( SafeCurlHandle curl, SslCtxCallback callback, ref SafeCallbackHandle callbackHandle);