c - Getting common name efficiently from tls certificate with openssl -

i have pointer tls certificate , need commonname property;

i @ first create x509 object function d2i_x509 ;

x = d2i_x509(null, &p, certificate_lenght); if (x == null)     return https_failure; 

than call function x509_name_get_text_by_nid getting commonname

x509_name_get_text_by_nid(x509_get_subject_name(x),nid_commonname, hc->https_domain_name, 256); 

it works me worried performance . think, certificate object parsed when need commonname . there better method getting commonname more efficiency .

there no more efficient way using openssl high-level api. if interested in having best performance possible, you'll need use low-level asn.1 parsing api. keep in mind cannot validate certificate without parsing entirely, concerned security implications of extracting cn.