filtering: imp cognit

internal/filtering/filtering.go

@@ -651,32 +651,14 @@ func hostsRewrites(
 	host string,
 	hs hostsfile.Storage,
 ) (vals []rules.RRValue, rs []*ResultRule) {
+	var isValidProto func(netip.Addr) (ok bool)
 	switch qtype {
 	case dns.TypeA:
-		for _, addr := range hs.ByName(host) {
-			if !addr.Is4() {
-				continue
-			}
-
-			vals = append(vals, addr)
-			rs = append(rs, &ResultRule{
-				Text:         fmt.Sprintf("%s %s", addr, host),
-				FilterListID: SysHostsListID,
-			})
-		}
+		isValidProto = netip.Addr.Is4
 	case dns.TypeAAAA:
-		for _, addr := range hs.ByName(host) {
-			if !addr.Is6() {
-				continue
-			}
-
-			vals = append(vals, addr)
-			rs = append(rs, &ResultRule{
-				Text:         fmt.Sprintf("%s %s", addr, host),
-				FilterListID: SysHostsListID,
-			})
-		}
+		isValidProto = netip.Addr.Is6
 	case dns.TypePTR:
+		// TODO(e.burkov):  Add some [netip]-aware alternative to [netutil].
 		ip, err := netutil.IPFromReversedAddr(host)
 		if err != nil {
 			log.Debug("filtering: failed to parse PTR record %q: %s", host, err)
@@ -693,8 +675,22 @@ func hostsRewrites(
 				FilterListID: SysHostsListID,
 			})
 		}
+
+		return vals, rs
 	default:
 		log.Debug("filtering: unsupported qtype %d", qtype)
+
+		return nil, nil
+	}
+
+	for _, addr := range hs.ByName(host) {
+		if isValidProto(addr) {
+			vals = append(vals, addr)
+			rs = append(rs, &ResultRule{
+				Text:         fmt.Sprintf("%s %s", addr, host),
+				FilterListID: SysHostsListID,
+			})
+		}
 	}
 
 	return vals, rs