v1.0.0

app/dns/udpns.go

@@ -0,0 +1,289 @@
+// +build !confonly
+
+package dns
+
+import (
+	"context"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/xtls/xray-core/v1/common"
+	"github.com/xtls/xray-core/v1/common/net"
+	"github.com/xtls/xray-core/v1/common/protocol/dns"
+	udp_proto "github.com/xtls/xray-core/v1/common/protocol/udp"
+	"github.com/xtls/xray-core/v1/common/session"
+	"github.com/xtls/xray-core/v1/common/signal/pubsub"
+	"github.com/xtls/xray-core/v1/common/task"
+	dns_feature "github.com/xtls/xray-core/v1/features/dns"
+	"github.com/xtls/xray-core/v1/features/routing"
+	"github.com/xtls/xray-core/v1/transport/internet/udp"
+	"golang.org/x/net/dns/dnsmessage"
+)
+
+type ClassicNameServer struct {
+	sync.RWMutex
+	name      string
+	address   net.Destination
+	ips       map[string]record
+	requests  map[uint16]dnsRequest
+	pub       *pubsub.Service
+	udpServer *udp.Dispatcher
+	cleanup   *task.Periodic
+	reqID     uint32
+	clientIP  net.IP
+}
+
+func NewClassicNameServer(address net.Destination, dispatcher routing.Dispatcher, clientIP net.IP) *ClassicNameServer {
+	// default to 53 if unspecific
+	if address.Port == 0 {
+		address.Port = net.Port(53)
+	}
+
+	s := &ClassicNameServer{
+		address:  address,
+		ips:      make(map[string]record),
+		requests: make(map[uint16]dnsRequest),
+		clientIP: clientIP,
+		pub:      pubsub.NewService(),
+		name:     strings.ToUpper(address.String()),
+	}
+	s.cleanup = &task.Periodic{
+		Interval: time.Minute,
+		Execute:  s.Cleanup,
+	}
+	s.udpServer = udp.NewDispatcher(dispatcher, s.HandleResponse)
+	newError("DNS: created udp client inited for ", address.NetAddr()).AtInfo().WriteToLog()
+	return s
+}
+
+func (s *ClassicNameServer) Name() string {
+	return s.name
+}
+
+func (s *ClassicNameServer) Cleanup() error {
+	now := time.Now()
+	s.Lock()
+	defer s.Unlock()
+
+	if len(s.ips) == 0 && len(s.requests) == 0 {
+		return newError(s.name, " nothing to do. stopping...")
+	}
+
+	for domain, record := range s.ips {
+		if record.A != nil && record.A.Expire.Before(now) {
+			record.A = nil
+		}
+		if record.AAAA != nil && record.AAAA.Expire.Before(now) {
+			record.AAAA = nil
+		}
+
+		if record.A == nil && record.AAAA == nil {
+			delete(s.ips, domain)
+		} else {
+			s.ips[domain] = record
+		}
+	}
+
+	if len(s.ips) == 0 {
+		s.ips = make(map[string]record)
+	}
+
+	for id, req := range s.requests {
+		if req.expire.Before(now) {
+			delete(s.requests, id)
+		}
+	}
+
+	if len(s.requests) == 0 {
+		s.requests = make(map[uint16]dnsRequest)
+	}
+
+	return nil
+}
+
+func (s *ClassicNameServer) HandleResponse(ctx context.Context, packet *udp_proto.Packet) {
+	ipRec, err := parseResponse(packet.Payload.Bytes())
+	if err != nil {
+		newError(s.name, " fail to parse responded DNS udp").AtError().WriteToLog()
+		return
+	}
+
+	s.Lock()
+	id := ipRec.ReqID
+	req, ok := s.requests[id]
+	if ok {
+		// remove the pending request
+		delete(s.requests, id)
+	}
+	s.Unlock()
+	if !ok {
+		newError(s.name, " cannot find the pending request").AtError().WriteToLog()
+		return
+	}
+
+	var rec record
+	switch req.reqType {
+	case dnsmessage.TypeA:
+		rec.A = ipRec
+	case dnsmessage.TypeAAAA:
+		rec.AAAA = ipRec
+	}
+
+	elapsed := time.Since(req.start)
+	newError(s.name, " got answer: ", req.domain, " ", req.reqType, " -> ", ipRec.IP, " ", elapsed).AtInfo().WriteToLog()
+	if len(req.domain) > 0 && (rec.A != nil || rec.AAAA != nil) {
+		s.updateIP(req.domain, rec)
+	}
+}
+
+func (s *ClassicNameServer) updateIP(domain string, newRec record) {
+	s.Lock()
+
+	newError(s.name, " updating IP records for domain:", domain).AtDebug().WriteToLog()
+	rec := s.ips[domain]
+
+	updated := false
+	if isNewer(rec.A, newRec.A) {
+		rec.A = newRec.A
+		updated = true
+	}
+	if isNewer(rec.AAAA, newRec.AAAA) {
+		rec.AAAA = newRec.AAAA
+		updated = true
+	}
+
+	if updated {
+		s.ips[domain] = rec
+	}
+	if newRec.A != nil {
+		s.pub.Publish(domain+"4", nil)
+	}
+	if newRec.AAAA != nil {
+		s.pub.Publish(domain+"6", nil)
+	}
+	s.Unlock()
+	common.Must(s.cleanup.Start())
+}
+
+func (s *ClassicNameServer) newReqID() uint16 {
+	return uint16(atomic.AddUint32(&s.reqID, 1))
+}
+
+func (s *ClassicNameServer) addPendingRequest(req *dnsRequest) {
+	s.Lock()
+	defer s.Unlock()
+
+	id := req.msg.ID
+	req.expire = time.Now().Add(time.Second * 8)
+	s.requests[id] = *req
+}
+
+func (s *ClassicNameServer) sendQuery(ctx context.Context, domain string, option IPOption) {
+	newError(s.name, " querying DNS for: ", domain).AtDebug().WriteToLog(session.ExportIDToError(ctx))
+
+	reqs := buildReqMsgs(domain, option, s.newReqID, genEDNS0Options(s.clientIP))
+
+	for _, req := range reqs {
+		s.addPendingRequest(req)
+		b, _ := dns.PackMessage(req.msg)
+		udpCtx := context.Background()
+		if inbound := session.InboundFromContext(ctx); inbound != nil {
+			udpCtx = session.ContextWithInbound(udpCtx, inbound)
+		}
+		udpCtx = session.ContextWithContent(udpCtx, &session.Content{
+			Protocol: "dns",
+		})
+		s.udpServer.Dispatch(udpCtx, s.address, b)
+	}
+}
+
+func (s *ClassicNameServer) findIPsForDomain(domain string, option IPOption) ([]net.IP, error) {
+	s.RLock()
+	record, found := s.ips[domain]
+	s.RUnlock()
+
+	if !found {
+		return nil, errRecordNotFound
+	}
+
+	var ips []net.Address
+	var lastErr error
+	if option.IPv4Enable {
+		a, err := record.A.getIPs()
+		if err != nil {
+			lastErr = err
+		}
+		ips = append(ips, a...)
+	}
+
+	if option.IPv6Enable {
+		aaaa, err := record.AAAA.getIPs()
+		if err != nil {
+			lastErr = err
+		}
+		ips = append(ips, aaaa...)
+	}
+
+	if len(ips) > 0 {
+		return toNetIP(ips), nil
+	}
+
+	if lastErr != nil {
+		return nil, lastErr
+	}
+
+	return nil, dns_feature.ErrEmptyResponse
+}
+
+func (s *ClassicNameServer) QueryIP(ctx context.Context, domain string, option IPOption) ([]net.IP, error) {
+	fqdn := Fqdn(domain)
+
+	ips, err := s.findIPsForDomain(fqdn, option)
+	if err != errRecordNotFound {
+		newError(s.name, " cache HIT ", domain, " -> ", ips).Base(err).AtDebug().WriteToLog()
+		return ips, err
+	}
+
+	// ipv4 and ipv6 belong to different subscription groups
+	var sub4, sub6 *pubsub.Subscriber
+	if option.IPv4Enable {
+		sub4 = s.pub.Subscribe(fqdn + "4")
+		defer sub4.Close()
+	}
+	if option.IPv6Enable {
+		sub6 = s.pub.Subscribe(fqdn + "6")
+		defer sub6.Close()
+	}
+	done := make(chan interface{})
+	go func() {
+		if sub4 != nil {
+			select {
+			case <-sub4.Wait():
+			case <-ctx.Done():
+			}
+		}
+		if sub6 != nil {
+			select {
+			case <-sub6.Wait():
+			case <-ctx.Done():
+			}
+		}
+		close(done)
+	}()
+	s.sendQuery(ctx, fqdn, option)
+
+	for {
+		ips, err := s.findIPsForDomain(fqdn, option)
+		if err != errRecordNotFound {
+			return ips, err
+		}
+
+		select {
+		case <-ctx.Done():
+			return nil, ctx.Err()
+		case <-done:
+		}
+	}
+}