mirror of https://github.com/XTLS/Xray-core
382 lines
9.4 KiB
Go
382 lines
9.4 KiB
Go
package dns
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"io/ioutil"
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"net/http"
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"net/url"
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"sync"
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"sync/atomic"
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"time"
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"github.com/xtls/xray-core/common"
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"github.com/xtls/xray-core/common/net"
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"github.com/xtls/xray-core/common/protocol/dns"
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"github.com/xtls/xray-core/common/session"
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"github.com/xtls/xray-core/common/signal/pubsub"
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"github.com/xtls/xray-core/common/task"
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dns_feature "github.com/xtls/xray-core/features/dns"
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"github.com/xtls/xray-core/features/routing"
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"github.com/xtls/xray-core/transport/internet"
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"golang.org/x/net/dns/dnsmessage"
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)
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// DoHNameServer implemented DNS over HTTPS (RFC8484) Wire Format,
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// which is compatible with traditional dns over udp(RFC1035),
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// thus most of the DOH implementation is copied from udpns.go
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type DoHNameServer struct {
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sync.RWMutex
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ips map[string]record
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pub *pubsub.Service
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cleanup *task.Periodic
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reqID uint32
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clientIP net.IP
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httpClient *http.Client
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dohURL string
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name string
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}
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// NewDoHNameServer creates DOH client object for remote resolving
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func NewDoHNameServer(url *url.URL, dispatcher routing.Dispatcher, clientIP net.IP) (*DoHNameServer, error) {
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newError("DNS: created Remote DOH client for ", url.String()).AtInfo().WriteToLog()
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s := baseDOHNameServer(url, "DOH", clientIP)
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// Dispatched connection will be closed (interrupted) after each request
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// This makes DOH inefficient without a keep-alived connection
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// See: core/app/proxyman/outbound/handler.go:113
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// Using mux (https request wrapped in a stream layer) improves the situation.
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// Recommend to use NewDoHLocalNameServer (DOHL:) if xray instance is running on
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// a normal network eg. the server side of xray
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tr := &http.Transport{
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MaxIdleConns: 30,
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IdleConnTimeout: 90 * time.Second,
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TLSHandshakeTimeout: 30 * time.Second,
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ForceAttemptHTTP2: true,
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DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
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dest, err := net.ParseDestination(network + ":" + addr)
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if err != nil {
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return nil, err
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}
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link, err := dispatcher.Dispatch(ctx, dest)
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if err != nil {
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return nil, err
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}
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return net.NewConnection(
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net.ConnectionInputMulti(link.Writer),
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net.ConnectionOutputMulti(link.Reader),
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), nil
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},
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}
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dispatchedClient := &http.Client{
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Transport: tr,
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Timeout: 60 * time.Second,
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}
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s.httpClient = dispatchedClient
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return s, nil
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}
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// NewDoHLocalNameServer creates DOH client object for local resolving
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func NewDoHLocalNameServer(url *url.URL, clientIP net.IP) *DoHNameServer {
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url.Scheme = "https"
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s := baseDOHNameServer(url, "DOHL", clientIP)
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tr := &http.Transport{
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IdleConnTimeout: 90 * time.Second,
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ForceAttemptHTTP2: true,
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DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
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dest, err := net.ParseDestination(network + ":" + addr)
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if err != nil {
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return nil, err
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}
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conn, err := internet.DialSystem(ctx, dest, nil)
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if err != nil {
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return nil, err
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}
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return conn, nil
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},
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}
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s.httpClient = &http.Client{
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Timeout: time.Second * 180,
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Transport: tr,
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}
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newError("DNS: created Local DOH client for ", url.String()).AtInfo().WriteToLog()
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return s
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}
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func baseDOHNameServer(url *url.URL, prefix string, clientIP net.IP) *DoHNameServer {
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s := &DoHNameServer{
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ips: make(map[string]record),
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clientIP: clientIP,
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pub: pubsub.NewService(),
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name: prefix + "//" + url.Host,
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dohURL: url.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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return s
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}
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// Name returns client name
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func (s *DoHNameServer) 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 *DoHNameServer) 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 {
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return newError("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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newError(s.name, " cleanup ", domain).AtDebug().WriteToLog()
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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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return nil
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}
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func (s *DoHNameServer) updateIP(req *dnsRequest, ipRec *IPRecord) {
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elapsed := time.Since(req.start)
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s.Lock()
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rec := s.ips[req.domain]
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updated := false
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switch req.reqType {
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case dnsmessage.TypeA:
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if isNewer(rec.A, ipRec) {
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rec.A = ipRec
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updated = true
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}
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case dnsmessage.TypeAAAA:
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addr := make([]net.Address, 0)
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for _, ip := range ipRec.IP {
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if len(ip.IP()) == net.IPv6len {
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addr = append(addr, ip)
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}
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}
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ipRec.IP = addr
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if isNewer(rec.AAAA, ipRec) {
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rec.AAAA = ipRec
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updated = true
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}
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}
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newError(s.name, " got answer: ", req.domain, " ", req.reqType, " -> ", ipRec.IP, " ", elapsed).AtInfo().WriteToLog()
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if updated {
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s.ips[req.domain] = rec
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}
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switch req.reqType {
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case dnsmessage.TypeA:
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s.pub.Publish(req.domain+"4", nil)
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case dnsmessage.TypeAAAA:
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s.pub.Publish(req.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 *DoHNameServer) newReqID() uint16 {
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return uint16(atomic.AddUint32(&s.reqID, 1))
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}
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func (s *DoHNameServer) sendQuery(ctx context.Context, domain string, option IPOption) {
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newError(s.name, " querying: ", domain).AtInfo().WriteToLog(session.ExportIDToError(ctx))
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reqs := buildReqMsgs(domain, option, s.newReqID, genEDNS0Options(s.clientIP))
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var deadline time.Time
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if d, ok := ctx.Deadline(); ok {
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deadline = d
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} else {
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deadline = time.Now().Add(time.Second * 5)
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}
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for _, req := range reqs {
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go func(r *dnsRequest) {
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// generate new context for each req, using same context
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// may cause reqs all aborted if any one encounter an error
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dnsCtx := context.Background()
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// reserve internal dns server requested Inbound
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if inbound := session.InboundFromContext(ctx); inbound != nil {
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dnsCtx = session.ContextWithInbound(dnsCtx, inbound)
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}
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dnsCtx = session.ContextWithContent(dnsCtx, &session.Content{
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Protocol: "https",
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SkipRoutePick: true,
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})
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// forced to use mux for DOH
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dnsCtx = session.ContextWithMuxPrefered(dnsCtx, true)
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var cancel context.CancelFunc
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dnsCtx, cancel = context.WithDeadline(dnsCtx, deadline)
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defer cancel()
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b, err := dns.PackMessage(r.msg)
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if err != nil {
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newError("failed to pack dns query").Base(err).AtError().WriteToLog()
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return
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}
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resp, err := s.dohHTTPSContext(dnsCtx, b.Bytes())
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if err != nil {
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newError("failed to retrieve response").Base(err).AtError().WriteToLog()
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return
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}
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rec, err := parseResponse(resp)
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if err != nil {
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newError("failed to handle DOH response").Base(err).AtError().WriteToLog()
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return
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}
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s.updateIP(r, rec)
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}(req)
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}
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}
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func (s *DoHNameServer) dohHTTPSContext(ctx context.Context, b []byte) ([]byte, error) {
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body := bytes.NewBuffer(b)
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req, err := http.NewRequest("POST", s.dohURL, body)
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if err != nil {
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return nil, err
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}
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req.Header.Add("Accept", "application/dns-message")
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req.Header.Add("Content-Type", "application/dns-message")
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resp, err := s.httpClient.Do(req.WithContext(ctx))
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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io.Copy(ioutil.Discard, resp.Body) // flush resp.Body so that the conn is reusable
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return nil, fmt.Errorf("DOH server returned code %d", resp.StatusCode)
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}
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return ioutil.ReadAll(resp.Body)
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}
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func (s *DoHNameServer) findIPsForDomain(domain string, option 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.IPv6Enable && record.AAAA != nil && record.AAAA.RCode == dnsmessage.RCodeSuccess {
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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 option.IPv4Enable && record.A != nil && record.A.RCode == dnsmessage.RCodeSuccess {
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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 len(ips) > 0 {
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return toNetIP(ips), nil
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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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if (option.IPv4Enable && record.A != nil) || (option.IPv6Enable && record.AAAA != nil) {
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return nil, dns_feature.ErrEmptyResponse
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}
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return nil, errRecordNotFound
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}
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// QueryIP is called from dns.Server->queryIPTimeout
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func (s *DoHNameServer) QueryIP(ctx context.Context, domain string, option IPOption) ([]net.IP, error) {
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fqdn := Fqdn(domain)
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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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// 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, 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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