Member openvpn::ClientProto::Session::do_acc_certcheck (const std::string &msg_str): std::string is perfectly OK for storing buffers containing null bytes but it's atypical.
Member openvpn::ConstBufferType< T >::reset_impl (const size_t min_capacity, const BufferFlags flags): Look into this odd one-off virtual dispatch + leakage of the flags parameter.
Member openvpn::intrusive_ptr_add_ref (R *rcptr) noexcept: consider removing debug cout
Member openvpn::intrusive_ptr_release (R *rcptr) noexcept: consider removing debug cout