X509V3_EXT_i2d
if ((ext = X509V3_EXT_i2d(nid, crit, ex)) == NULL)
x = X509V3_EXT_i2d(NID_id_pkix_OCSP_CrlID, 0, cid);
x = X509V3_EXT_i2d(NID_id_pkix_OCSP_acceptableResponses, 0, sk);
x = X509V3_EXT_i2d(NID_id_pkix_OCSP_archiveCutoff, 0, gt);
x = X509V3_EXT_i2d(NID_id_pkix_OCSP_serviceLocator, 0, sloc);
ext = X509V3_EXT_i2d(nid, crit, value);
X509_EXTENSION *X509V3_EXT_i2d(int ext_nid, int crit, void *ext_struc);