package dns import ( "context" "crypto/tls" "errors" "fmt" "net" "net/netip" "strings" "time" "github.com/Dreamacro/clash/common/cache" N "github.com/Dreamacro/clash/common/net" "github.com/Dreamacro/clash/common/nnip" "github.com/Dreamacro/clash/common/picker" "github.com/Dreamacro/clash/component/dialer" "github.com/Dreamacro/clash/component/resolver" C "github.com/Dreamacro/clash/constant" "github.com/Dreamacro/clash/log" "github.com/Dreamacro/clash/tunnel" D "github.com/miekg/dns" ) const ( MaxMsgSize = 65535 ) func putMsgToCache(c *cache.LruCache[string, *D.Msg], key string, msg *D.Msg) { // skip dns cache for acme challenge if len(msg.Question) != 0 { if q := msg.Question[0]; q.Qtype == D.TypeTXT && strings.HasPrefix(q.Name, "_acme-challenge") { log.Debugln("[DNS] dns cache ignored because of acme challenge for: %s", q.Name) return } } var ttl uint32 switch { case len(msg.Answer) != 0: ttl = msg.Answer[0].Header().Ttl case len(msg.Ns) != 0: ttl = msg.Ns[0].Header().Ttl case len(msg.Extra) != 0: ttl = msg.Extra[0].Header().Ttl default: log.Debugln("[DNS] response msg empty: %#v", msg) return } c.SetWithExpire(key, msg.Copy(), time.Now().Add(time.Second*time.Duration(ttl))) } func setMsgTTL(msg *D.Msg, ttl uint32) { for _, answer := range msg.Answer { answer.Header().Ttl = ttl } for _, ns := range msg.Ns { ns.Header().Ttl = ttl } for _, extra := range msg.Extra { extra.Header().Ttl = ttl } } func isIPRequest(q D.Question) bool { return q.Qclass == D.ClassINET && (q.Qtype == D.TypeA || q.Qtype == D.TypeAAAA) } func transform(servers []NameServer, resolver *Resolver) []dnsClient { ret := []dnsClient{} for _, s := range servers { switch s.Net { case "https": ret = append(ret, newDoHClient(s.Addr, resolver, s.PreferH3, s.Params, s.ProxyAdapter)) continue case "dhcp": ret = append(ret, newDHCPClient(s.Addr)) continue case "quic": if doq, err := newDoQ(resolver, s.Addr, s.ProxyAdapter); err == nil { ret = append(ret, doq) } else { log.Fatalln("DoQ format error: %v", err) } continue } host, port, _ := net.SplitHostPort(s.Addr) ret = append(ret, &client{ Client: &D.Client{ Net: s.Net, TLSConfig: &tls.Config{ ServerName: host, }, UDPSize: 4096, Timeout: 5 * time.Second, }, port: port, host: host, iface: s.Interface, r: resolver, proxyAdapter: s.ProxyAdapter, }) } return ret } func handleMsgWithEmptyAnswer(r *D.Msg) *D.Msg { msg := &D.Msg{} msg.Answer = []D.RR{} msg.SetRcode(r, D.RcodeSuccess) msg.Authoritative = true msg.RecursionAvailable = true return msg } func msgToIP(msg *D.Msg) []netip.Addr { ips := []netip.Addr{} for _, answer := range msg.Answer { switch ans := answer.(type) { case *D.AAAA: ips = append(ips, nnip.IpToAddr(ans.AAAA)) case *D.A: ips = append(ips, nnip.IpToAddr(ans.A)) } } return ips } func msgToDomain(msg *D.Msg) string { if len(msg.Question) > 0 { return strings.TrimRight(msg.Question[0].Name, ".") } return "" } type dialHandler func(ctx context.Context, network, addr string) (net.Conn, error) func getDialHandler(r *Resolver, proxyAdapter string, opts ...dialer.Option) dialHandler { return func(ctx context.Context, network, addr string) (net.Conn, error) { if len(proxyAdapter) == 0 { opts = append(opts, dialer.WithResolver(r)) return dialer.DialContext(ctx, network, addr, opts...) } else { host, port, err := net.SplitHostPort(addr) if err != nil { return nil, err } adapter, ok := tunnel.Proxies()[proxyAdapter] if !ok { opts = append(opts, dialer.WithInterface(proxyAdapter)) } if strings.Contains(network, "tcp") { // tcp can resolve host by remote metadata := &C.Metadata{ NetWork: C.TCP, Host: host, DstPort: port, } if ok { return adapter.DialContext(ctx, metadata, opts...) } opts = append(opts, dialer.WithResolver(r)) return dialer.DialContext(ctx, network, addr, opts...) } else { // udp must resolve host first dstIP, err := resolver.ResolveIPWithResolver(ctx, host, r) if err != nil { return nil, err } metadata := &C.Metadata{ NetWork: C.UDP, Host: "", DstIP: dstIP, DstPort: port, } if !ok { return dialer.DialContext(ctx, network, addr, opts...) } if !adapter.SupportUDP() { return nil, fmt.Errorf("proxy adapter [%s] UDP is not supported", proxyAdapter) } packetConn, err := adapter.ListenPacketContext(ctx, metadata, opts...) if err != nil { return nil, err } return N.NewBindPacketConn(packetConn, metadata.UDPAddr()), nil } } } } func listenPacket(ctx context.Context, proxyAdapter string, network string, addr string, r *Resolver, opts ...dialer.Option) (net.PacketConn, error) { host, port, err := net.SplitHostPort(addr) if err != nil { return nil, err } adapter, ok := tunnel.Proxies()[proxyAdapter] if !ok && len(proxyAdapter) != 0 { opts = append(opts, dialer.WithInterface(proxyAdapter)) } // udp must resolve host first dstIP, err := resolver.ResolveIPWithResolver(ctx, host, r) if err != nil { return nil, err } metadata := &C.Metadata{ NetWork: C.UDP, Host: "", DstIP: dstIP, DstPort: port, } if !ok { return dialer.ListenPacket(ctx, dialer.ParseNetwork(network, dstIP), "", opts...) } if !adapter.SupportUDP() { return nil, fmt.Errorf("proxy adapter [%s] UDP is not supported", proxyAdapter) } return adapter.ListenPacketContext(ctx, metadata, opts...) } func batchExchange(ctx context.Context, clients []dnsClient, m *D.Msg) (msg *D.Msg, err error) { fast, ctx := picker.WithTimeout[*D.Msg](ctx, resolver.DefaultDNSTimeout) for _, client := range clients { r := client fast.Go(func() (*D.Msg, error) { m, err := r.ExchangeContext(ctx, m) if err != nil { return nil, err } else if m.Rcode == D.RcodeServerFailure || m.Rcode == D.RcodeRefused { return nil, errors.New("server failure") } return m, nil }) } elm := fast.Wait() if elm == nil { err := errors.New("all DNS requests failed") if fErr := fast.Error(); fErr != nil { err = fmt.Errorf("%w, first error: %s", err, fErr.Error()) } return nil, err } msg = elm return }