X509_EXTENSION_create_by_NID
ext = X509_EXTENSION_create_by_NID(NULL, ext_nid, crit, ext_oct);
X509_EXTENSION *X509_EXTENSION_create_by_NID(X509_EXTENSION **ex,
ext = X509_EXTENSION_create_by_NID(NULL, NID_subject_alt_name, 0, data);