package dns import ( "errors" "net" "github.com/Dreamacro/clash/common/sockopt" "github.com/Dreamacro/clash/context" "github.com/Dreamacro/clash/log" D "github.com/miekg/dns" ) var ( address string server = &Server{} dnsDefaultTTL uint32 = 600 ) type Server struct { *D.Server handler handler } // ServeDNS implement D.Handler ServeDNS func (s *Server) ServeDNS(w D.ResponseWriter, r *D.Msg) { msg, err := handlerWithContext(s.handler, r) if err != nil { D.HandleFailed(w, r) return } msg.Compress = true w.WriteMsg(msg) } func handlerWithContext(handler handler, msg *D.Msg) (*D.Msg, error) { if len(msg.Question) == 0 { return nil, errors.New("at least one question is required") } ctx := context.NewDNSContext(msg) return handler(ctx, msg) } func (s *Server) setHandler(handler handler) { s.handler = handler } func ReCreateServer(addr string, resolver *Resolver, mapper *ResolverEnhancer) { if addr == address && resolver != nil { handler := newHandler(resolver, mapper) server.setHandler(handler) return } if server.Server != nil { server.Shutdown() server = &Server{} address = "" } if addr == "" { return } var err error defer func() { if err != nil { log.Errorln("Start DNS server error: %s", err.Error()) } }() _, port, err := net.SplitHostPort(addr) if port == "0" || port == "" || err != nil { return } udpAddr, err := net.ResolveUDPAddr("udp", addr) if err != nil { return } p, err := net.ListenUDP("udp", udpAddr) if err != nil { return } err = sockopt.UDPReuseaddr(p) if err != nil { log.Warnln("Failed to Reuse UDP Address: %s", err) err = nil } address = addr handler := newHandler(resolver, mapper) server = &Server{handler: handler} server.Server = &D.Server{Addr: addr, PacketConn: p, Handler: server} go func() { server.ActivateAndServe() }() log.Infoln("DNS server listening at: %s", p.LocalAddr().String()) }