Add ErrAlreadyExists

dnsfilter/dnsfilter.go

@@ -33,9 +33,12 @@ const defaultSafebrowsingURL = "http://%s/safebrowsing-lookup-hash.html?prefixes
 const defaultParentalServer = "pctrl.adguard.com"
 const defaultParentalURL = "http://%s/check-parental-control-hash?prefixes=%s&sensitivity=%d"
 
-// ErrInvalidSyntax is returned by AddRule when rule is invalid
+// ErrInvalidSyntax is returned by AddRule when the rule is invalid
 var ErrInvalidSyntax = errors.New("dnsfilter: invalid rule syntax")
 
+// ErrInvalidSyntax is returned by AddRule when the rule was already added to the filter
+var ErrAlreadyExists = errors.New("dnsfilter: rule was already added")
+
 // ErrInvalidParental is returned by EnableParental when sensitivity is not a valid value
 var ErrInvalidParental = errors.New("dnsfilter: invalid parental sensitivity, must be either 3, 10, 13 or 17")
 
@@ -737,8 +740,7 @@ func (d *Dnsfilter) AddRule(input string, filterListID uint32) error {
 	d.storageMutex.RUnlock()
 	if exists {
 		// already added
-		// TODO: Change the error type
-		return ErrInvalidSyntax
+		return ErrAlreadyExists
 	}
 
 	if !isValidRule(input) {

dnsfilter/dnsfilter_test.go

@@ -261,7 +261,7 @@ func (d *Dnsfilter) checkAddRule(t *testing.T, rule string) {
 func (d *Dnsfilter) checkAddRuleFail(t *testing.T, rule string) {
 	t.Helper()
 	err := d.AddRule(rule, 0)
-	if err == ErrInvalidSyntax {
+	if err == ErrInvalidSyntax || err == ErrAlreadyExists {
 		return
 	}
 	if err != nil {
@@ -318,7 +318,7 @@ func loadTestRules(d *Dnsfilter) error {
 	for scanner.Scan() {
 		rule := scanner.Text()
 		err = d.AddRule(rule, 0)
-		if err == ErrInvalidSyntax {
+		if err == ErrInvalidSyntax || err == ErrAlreadyExists {
 			continue
 		}
 		if err != nil {
@@ -724,6 +724,7 @@ func BenchmarkAddRule(b *testing.B) {
 		err := d.AddRule(rule, 0)
 		switch err {
 		case nil:
+		case ErrAlreadyExists: // ignore rules which were already added
 		case ErrInvalidSyntax: // ignore invalid syntax
 		default:
 			b.Fatalf("Error while adding rule %s: %s", rule, err)
@@ -743,6 +744,7 @@ func BenchmarkAddRuleParallel(b *testing.B) {
 		}
 		switch err {
 		case nil:
+		case ErrAlreadyExists: // ignore rules which were already added
 		case ErrInvalidSyntax: // ignore invalid syntax
 		default:
 			b.Fatalf("Error while adding rule %s: %s", rule, err)