mirror of https://github.com/v2fly/v2ray-core.git
298 lines
6.8 KiB
Go
298 lines
6.8 KiB
Go
package dns
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import (
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"context"
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"strings"
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"sync"
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"sync/atomic"
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"time"
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"golang.org/x/net/dns/dnsmessage"
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core "github.com/v2fly/v2ray-core/v4"
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"github.com/v2fly/v2ray-core/v4/common"
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"github.com/v2fly/v2ray-core/v4/common/net"
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"github.com/v2fly/v2ray-core/v4/common/protocol/dns"
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udp_proto "github.com/v2fly/v2ray-core/v4/common/protocol/udp"
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"github.com/v2fly/v2ray-core/v4/common/session"
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"github.com/v2fly/v2ray-core/v4/common/signal/pubsub"
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"github.com/v2fly/v2ray-core/v4/common/task"
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dns_feature "github.com/v2fly/v2ray-core/v4/features/dns"
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"github.com/v2fly/v2ray-core/v4/features/routing"
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"github.com/v2fly/v2ray-core/v4/transport/internet/udp"
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)
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// ClassicNameServer implemented traditional UDP DNS.
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type ClassicNameServer struct {
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sync.RWMutex
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name string
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address net.Destination
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ips map[string]record
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requests map[uint16]dnsRequest
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pub *pubsub.Service
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udpServer *udp.Dispatcher
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cleanup *task.Periodic
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reqID uint32
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}
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// NewClassicNameServer creates udp server object for remote resolving.
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func NewClassicNameServer(address net.Destination, dispatcher routing.Dispatcher) *ClassicNameServer {
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// default to 53 if unspecific
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if address.Port == 0 {
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address.Port = net.Port(53)
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}
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s := &ClassicNameServer{
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address: address,
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ips: make(map[string]record),
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requests: make(map[uint16]dnsRequest),
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pub: pubsub.NewService(),
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name: strings.ToUpper(address.String()),
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}
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s.cleanup = &task.Periodic{
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Interval: time.Minute,
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Execute: s.Cleanup,
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}
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s.udpServer = udp.NewDispatcher(dispatcher, s.HandleResponse)
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newError("DNS: created UDP client initialized for ", address.NetAddr()).AtInfo().WriteToLog()
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return s
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}
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// Name implements Server.
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func (s *ClassicNameServer) Name() string {
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return s.name
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}
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// Cleanup clears expired items from cache
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func (s *ClassicNameServer) Cleanup() error {
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now := time.Now()
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s.Lock()
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defer s.Unlock()
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if len(s.ips) == 0 && len(s.requests) == 0 {
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return newError(s.name, " nothing to do. stopping...")
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}
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for domain, record := range s.ips {
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if record.A != nil && record.A.Expire.Before(now) {
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record.A = nil
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}
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if record.AAAA != nil && record.AAAA.Expire.Before(now) {
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record.AAAA = nil
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}
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if record.A == nil && record.AAAA == nil {
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delete(s.ips, domain)
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} else {
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s.ips[domain] = record
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}
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}
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if len(s.ips) == 0 {
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s.ips = make(map[string]record)
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}
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for id, req := range s.requests {
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if req.expire.Before(now) {
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delete(s.requests, id)
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}
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}
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if len(s.requests) == 0 {
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s.requests = make(map[uint16]dnsRequest)
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}
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return nil
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}
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// HandleResponse handles udp response packet from remote DNS server.
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func (s *ClassicNameServer) HandleResponse(ctx context.Context, packet *udp_proto.Packet) {
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ipRec, err := parseResponse(packet.Payload.Bytes())
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if err != nil {
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newError(s.name, " fail to parse responded DNS udp").AtError().WriteToLog()
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return
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}
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s.Lock()
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id := ipRec.ReqID
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req, ok := s.requests[id]
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if ok {
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// remove the pending request
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delete(s.requests, id)
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}
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s.Unlock()
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if !ok {
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newError(s.name, " cannot find the pending request").AtError().WriteToLog()
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return
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}
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var rec record
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switch req.reqType {
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case dnsmessage.TypeA:
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rec.A = ipRec
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case dnsmessage.TypeAAAA:
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rec.AAAA = ipRec
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}
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elapsed := time.Since(req.start)
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newError(s.name, " got answer: ", req.domain, " ", req.reqType, " -> ", ipRec.IP, " ", elapsed).AtInfo().WriteToLog()
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if len(req.domain) > 0 && (rec.A != nil || rec.AAAA != nil) {
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s.updateIP(req.domain, rec)
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}
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}
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func (s *ClassicNameServer) updateIP(domain string, newRec record) {
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s.Lock()
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newError(s.name, " updating IP records for domain:", domain).AtDebug().WriteToLog()
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rec := s.ips[domain]
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updated := false
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if isNewer(rec.A, newRec.A) {
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rec.A = newRec.A
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updated = true
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}
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if isNewer(rec.AAAA, newRec.AAAA) {
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rec.AAAA = newRec.AAAA
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updated = true
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}
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if updated {
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s.ips[domain] = rec
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}
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if newRec.A != nil {
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s.pub.Publish(domain+"4", nil)
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}
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if newRec.AAAA != nil {
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s.pub.Publish(domain+"6", nil)
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}
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s.Unlock()
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common.Must(s.cleanup.Start())
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}
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func (s *ClassicNameServer) newReqID() uint16 {
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return uint16(atomic.AddUint32(&s.reqID, 1))
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}
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func (s *ClassicNameServer) addPendingRequest(req *dnsRequest) {
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s.Lock()
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defer s.Unlock()
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id := req.msg.ID
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req.expire = time.Now().Add(time.Second * 8)
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s.requests[id] = *req
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}
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func (s *ClassicNameServer) sendQuery(ctx context.Context, domain string, clientIP net.IP, option dns_feature.IPOption) {
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newError(s.name, " querying DNS for: ", domain).AtDebug().WriteToLog(session.ExportIDToError(ctx))
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reqs := buildReqMsgs(domain, option, s.newReqID, genEDNS0Options(clientIP))
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for _, req := range reqs {
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s.addPendingRequest(req)
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b, _ := dns.PackMessage(req.msg)
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udpCtx := core.ToBackgroundDetachedContext(ctx)
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if inbound := session.InboundFromContext(ctx); inbound != nil {
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udpCtx = session.ContextWithInbound(udpCtx, inbound)
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}
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udpCtx = session.ContextWithContent(udpCtx, &session.Content{
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Protocol: "dns",
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})
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s.udpServer.Dispatch(udpCtx, s.address, b)
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}
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}
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func (s *ClassicNameServer) findIPsForDomain(domain string, option dns_feature.IPOption) ([]net.IP, error) {
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s.RLock()
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record, found := s.ips[domain]
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s.RUnlock()
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if !found {
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return nil, errRecordNotFound
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}
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var ips []net.Address
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var lastErr error
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if option.IPv4Enable {
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a, err := record.A.getIPs()
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if err != nil {
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lastErr = err
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}
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ips = append(ips, a...)
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}
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if option.IPv6Enable {
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aaaa, err := record.AAAA.getIPs()
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if err != nil {
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lastErr = err
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}
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ips = append(ips, aaaa...)
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}
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if len(ips) > 0 {
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return toNetIP(ips)
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}
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if lastErr != nil {
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return nil, lastErr
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}
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return nil, dns_feature.ErrEmptyResponse
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}
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// QueryIP implements Server.
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func (s *ClassicNameServer) QueryIP(ctx context.Context, domain string, clientIP net.IP, option dns_feature.IPOption, disableCache bool) ([]net.IP, error) {
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fqdn := Fqdn(domain)
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if disableCache {
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newError("DNS cache is disabled. Querying IP for ", domain, " at ", s.name).AtDebug().WriteToLog()
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} else {
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ips, err := s.findIPsForDomain(fqdn, option)
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if err != errRecordNotFound {
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newError(s.name, " cache HIT ", domain, " -> ", ips).Base(err).AtDebug().WriteToLog()
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return ips, err
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}
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}
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// ipv4 and ipv6 belong to different subscription groups
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var sub4, sub6 *pubsub.Subscriber
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if option.IPv4Enable {
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sub4 = s.pub.Subscribe(fqdn + "4")
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defer sub4.Close()
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}
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if option.IPv6Enable {
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sub6 = s.pub.Subscribe(fqdn + "6")
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defer sub6.Close()
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}
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done := make(chan interface{})
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go func() {
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if sub4 != nil {
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select {
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case <-sub4.Wait():
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case <-ctx.Done():
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}
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}
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if sub6 != nil {
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select {
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case <-sub6.Wait():
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case <-ctx.Done():
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}
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}
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close(done)
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}()
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s.sendQuery(ctx, fqdn, clientIP, option)
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for {
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ips, err := s.findIPsForDomain(fqdn, option)
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if err != errRecordNotFound {
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return ips, err
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}
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select {
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case <-ctx.Done():
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return nil, ctx.Err()
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case <-done:
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}
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}
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}
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