[client] Add TCP DNS support for local listener (#5758)

client/internal/dns/service.go

@@ -4,15 +4,25 @@ import (
 	"net/netip"
 
 	"github.com/miekg/dns"
+
+	firewall "github.com/netbirdio/netbird/client/firewall/manager"
 )
 
 const (
 	DefaultPort = 53
 )
 
+// Firewall provides DNAT capabilities for DNS port redirection.
+// This is used when the DNS server cannot bind port 53 directly
+// and needs firewall rules to redirect traffic.
+type Firewall interface {
+	AddOutputDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error
+	RemoveOutputDNAT(localAddr netip.Addr, protocol firewall.Protocol, sourcePort, targetPort uint16) error
+}
+
 type service interface {
 	Listen() error
-	Stop()
+	Stop() error
 	RegisterMux(domain string, handler dns.Handler)
 	DeregisterMux(key string)
 	RuntimePort() int