fix dn parsing without attr or value

fixes #114

dn.go

@@ -143,6 +143,9 @@ func ParseDN(str string) (*DN, error) {
 			}
 		} else if char == ',' || char == '+' {
 			// We're done with this RDN or value, push it
+			if len(attribute.Type) == 0 {
+				return nil, errors.New("incomplete type, value pair")
+			}
 			attribute.Value = stringFromBuffer()
 			rdn.Attributes = append(rdn.Attributes, attribute)
 			attribute = new(AttributeTypeAndValue)

dn_test.go

@@ -75,11 +75,12 @@ func TestSuccessfulDNParsing(t *testing.T) {
 
 func TestErrorDNParsing(t *testing.T) {
 	testcases := map[string]string{
-		"*":               "DN ended with incomplete type, value pair",
-		"cn=Jim\\0Test":   "Failed to decode escaped character: encoding/hex: invalid byte: U+0054 'T'",
-		"cn=Jim\\0":       "Got corrupted escaped character",
-		"DC=example,=net": "DN ended with incomplete type, value pair",
-		"1=#0402486":      "Failed to decode BER encoding: encoding/hex: odd length hex string",
+		"*":                      "DN ended with incomplete type, value pair",
+		"cn=Jim\\0Test":          "Failed to decode escaped character: encoding/hex: invalid byte: U+0054 'T'",
+		"cn=Jim\\0":              "Got corrupted escaped character",
+		"DC=example,=net":        "DN ended with incomplete type, value pair",
+		"1=#0402486":             "Failed to decode BER encoding: encoding/hex: odd length hex string",
+		"test,DC=example,DC=com": "incomplete type, value pair",
 	}
 
 	for test, answer := range testcases {