package dns import ( "errors" "fmt" "net" "time" "github.com/Dreamacro/clash/log" "github.com/miekg/dns" D "github.com/miekg/dns" ) var ( address string server = &Server{} dnsDefaultTTL uint32 = 600 ) type Server struct { *D.Server r *Resolver } func (s *Server) ServeDNS(w D.ResponseWriter, r *D.Msg) { if s.r.IsFakeIP() { msg, err := s.handleFakeIP(r) if err != nil { D.HandleFailed(w, r) return } msg.SetReply(r) w.WriteMsg(msg) return } msg, err := s.r.Exchange(r) if err != nil { if len(r.Question) > 0 { q := r.Question[0] qString := fmt.Sprintf("%s %s %s", q.Name, D.Class(q.Qclass).String(), D.Type(q.Qtype).String()) log.Debugln("[DNS Server] Exchange %s failed: %v", qString, err) } D.HandleFailed(w, r) return } msg.SetReply(r) w.WriteMsg(msg) } func (s *Server) handleFakeIP(r *D.Msg) (msg *D.Msg, err error) { if len(r.Question) == 0 { err = errors.New("should have one question at least") return } q := r.Question[0] cache, expireTime := s.r.cache.GetWithExpire("fakeip:" + q.String()) if cache != nil { msg = cache.(*D.Msg).Copy() setMsgTTL(msg, uint32(expireTime.Sub(time.Now()).Seconds())) return } var ip net.IP defer func() { if msg == nil { return } putMsgToCache(s.r.cache, "fakeip:"+q.String(), msg) putMsgToCache(s.r.cache, ip.String(), msg) }() rr := &D.A{} rr.Hdr = dns.RR_Header{Name: r.Question[0].Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: dnsDefaultTTL} ip = s.r.pool.Get() rr.A = ip msg = r.Copy() msg.Answer = []D.RR{rr} return } func (s *Server) setReslover(r *Resolver) { s.r = r } func ReCreateServer(addr string, resolver *Resolver) error { if addr == address { server.setReslover(resolver) return nil } if server.Server != nil { server.Shutdown() } _, port, err := net.SplitHostPort(addr) if port == "0" || port == "" || err != nil { return nil } udpAddr, err := net.ResolveUDPAddr("udp", addr) if err != nil { return err } p, err := net.ListenUDP("udp", udpAddr) if err != nil { return err } address = addr server = &Server{r: resolver} server.Server = &D.Server{Addr: addr, PacketConn: p, Handler: server} go func() { server.ActivateAndServe() }() return nil }