Function has_must_staple_extension 

pub fn has_must_staple_extension(cert_der: &[u8]) -> bool

Check whether a DER-encoded certificate contains the TLS Feature Extension (must-staple, OID 1.3.6.1.5.5.7.1.24).

RFC 7633 Section 4: if this extension is present with value status_request(5), the TLS server MUST provide a stapled OCSP response during every handshake.