create_ext

static VALUE
ossl_x509extfactory_create_ext(int argc, VALUE *argv, VALUE self)
{
    X509V3_CTX *ctx;
    X509_EXTENSION *ext;
    VALUE oid, value, critical, valstr, obj;
    int nid;
    VALUE rconf;
    CONF *conf;

    rb_scan_args(argc, argv, "21", &oid, &value, &critical);
    StringValueCStr(oid);
    StringValue(value);
    if(NIL_P(critical)) critical = Qfalse;

    nid = OBJ_ln2nid(RSTRING_PTR(oid));
    if(!nid) nid = OBJ_sn2nid(RSTRING_PTR(oid));
    if(!nid) ossl_raise(eX509ExtError, "unknown OID `%"PRIsVALUE"'", oid);

    valstr = rb_str_new2(RTEST(critical) ? "critical," : "");
    rb_str_append(valstr, value);
    StringValueCStr(valstr);

    GetX509ExtFactory(self, ctx);
    obj = NewX509Ext(cX509Ext);
    rconf = rb_iv_get(self, "@config");
    conf = NIL_P(rconf) ? NULL : DupConfigPtr(rconf);
    X509V3_set_nconf(ctx, conf);
    ext = X509V3_EXT_nconf_nid(conf, ctx, nid, RSTRING_PTR(valstr));
    X509V3_set_ctx_nodb(ctx);
    NCONF_free(conf);
    if (!ext){
        ossl_raise(eX509ExtError, "%"PRIsVALUE" = %"PRIsVALUE, oid, valstr);
    }
    SetX509Ext(obj, ext);

    return obj;
}