asn1: prohibit indefinite length form for primitive encoding

The setter method #indefinite_length= for OpenSSL::ASN1::Primitive is
undef-ed, but we can still set 'indefinite_length' to true illegally
when constructing an object with the raw OpenSSL::ASN1::ASN1Data.

Indefinite length form is not possible in primitive encoding. Raise an
exception in OpenSSL::ASN1::ASN1Data#to_der if specified.

Author: rhenium

ext/openssl/ossl_asn1.c

@@ -716,6 +716,8 @@ ossl_asn1data_to_der(VALUE self)
     tag_class = ossl_asn1_tag_class(self);
     inf_length = ossl_asn1_get_indefinite_length(self);
     if (inf_length == Qtrue) {
+	if (is_cons == 0)
+	    ossl_raise(eASN1Error, "indefinite form used for primitive encoding");
 	is_cons = 2;
     }
     if((length = ASN1_object_size(is_cons, RSTRING_LENINT(value), tag)) <= 0)

test/test_asn1.rb

@@ -426,6 +426,9 @@ def test_basic_asn1data
     ], 1, :APPLICATION)
     obj.indefinite_length = true
     encode_decode_test B(%w{ 61 80 C2 02 AB CD 00 00 }), obj
+    obj = OpenSSL::ASN1::ASN1Data.new(B(%w{ AB CD }), 1, :UNIVERSAL)
+    obj.indefinite_length = true
+    assert_raise(OpenSSL::ASN1::ASN1Error) { obj.to_der }
   end
 
   def test_basic_primitive