Refactored ngx_quic_close_connection(). The function is split into three: ngx_quic_close_connection() itself cleans up all core nginx things ngx_quic_close_quic() deals with everything inside c->quic ngx_quic_close_streams() deals with streams cleanup The quic and streams cleanup functions may return NGX_AGAIN, thus signalling that cleanup is not ready yet, and the close cannot continue to next step.