initial commit
This commit is contained in:
ginuerzh
280
handler/dns/handler.go
Normal file
280
handler/dns/handler.go
Normal file
@ -0,0 +1,280 @@
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package dns
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import (
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"bytes"
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"context"
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"errors"
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"fmt"
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"net"
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"strconv"
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"strings"
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"time"
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"github.com/go-gost/gost/v3/pkg/chain"
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"github.com/go-gost/gost/v3/pkg/common/bufpool"
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resolver_util "github.com/go-gost/gost/v3/pkg/common/util/resolver"
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"github.com/go-gost/gost/v3/pkg/handler"
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"github.com/go-gost/gost/v3/pkg/hosts"
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"github.com/go-gost/gost/v3/pkg/logger"
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md "github.com/go-gost/gost/v3/pkg/metadata"
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"github.com/go-gost/gost/v3/pkg/registry"
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"github.com/go-gost/gost/v3/pkg/resolver/exchanger"
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"github.com/miekg/dns"
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)
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const (
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defaultNameserver = "udp://127.0.0.1:53"
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)
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func init() {
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registry.HandlerRegistry().Register("dns", NewHandler)
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}
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type dnsHandler struct {
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exchangers []exchanger.Exchanger
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cache *resolver_util.Cache
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router *chain.Router
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hosts hosts.HostMapper
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md metadata
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options handler.Options
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}
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func NewHandler(opts ...handler.Option) handler.Handler {
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options := handler.Options{}
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for _, opt := range opts {
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opt(&options)
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}
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return &dnsHandler{
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options: options,
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}
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}
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func (h *dnsHandler) Init(md md.Metadata) (err error) {
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if err = h.parseMetadata(md); err != nil {
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return
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}
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log := h.options.Logger
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h.cache = resolver_util.NewCache().WithLogger(log)
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h.router = h.options.Router
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if h.router == nil {
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h.router = (&chain.Router{}).WithLogger(log)
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}
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h.hosts = h.router.Hosts()
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for _, server := range h.md.dns {
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server = strings.TrimSpace(server)
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if server == "" {
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continue
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}
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ex, err := exchanger.NewExchanger(
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server,
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exchanger.RouterOption(h.router),
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exchanger.TimeoutOption(h.md.timeout),
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exchanger.LoggerOption(log),
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)
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if err != nil {
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log.Warnf("parse %s: %v", server, err)
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continue
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}
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h.exchangers = append(h.exchangers, ex)
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}
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if len(h.exchangers) == 0 {
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ex, err := exchanger.NewExchanger(
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defaultNameserver,
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exchanger.RouterOption(h.router),
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exchanger.TimeoutOption(h.md.timeout),
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exchanger.LoggerOption(log),
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)
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log.Warnf("resolver not found, default to %s", defaultNameserver)
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if err != nil {
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return err
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}
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h.exchangers = append(h.exchangers, ex)
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}
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return
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}
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func (h *dnsHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
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defer conn.Close()
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start := time.Now()
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log := h.options.Logger.WithFields(map[string]any{
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"remote": conn.RemoteAddr().String(),
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"local": conn.LocalAddr().String(),
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})
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log.Infof("%s <> %s", conn.RemoteAddr(), conn.LocalAddr())
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defer func() {
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log.WithFields(map[string]any{
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"duration": time.Since(start),
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}).Infof("%s >< %s", conn.RemoteAddr(), conn.LocalAddr())
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}()
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b := bufpool.Get(4096)
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defer bufpool.Put(b)
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n, err := conn.Read(*b)
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if err != nil {
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log.Error(err)
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return err
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}
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reply, err := h.exchange(ctx, (*b)[:n], log)
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if err != nil {
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return err
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}
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defer bufpool.Put(&reply)
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if _, err = conn.Write(reply); err != nil {
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log.Error(err)
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return err
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}
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return nil
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}
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func (h *dnsHandler) exchange(ctx context.Context, msg []byte, log logger.Logger) ([]byte, error) {
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mq := dns.Msg{}
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if err := mq.Unpack(msg); err != nil {
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log.Error(err)
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return nil, err
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}
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if len(mq.Question) == 0 {
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return nil, errors.New("msg: empty question")
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}
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resolver_util.AddSubnetOpt(&mq, h.md.clientIP)
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if log.IsLevelEnabled(logger.DebugLevel) {
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log.Debug(mq.String())
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}
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var mr *dns.Msg
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if log.IsLevelEnabled(logger.DebugLevel) {
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defer func() {
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if mr != nil {
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log.Debug(mr.String())
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}
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}()
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}
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mr = h.lookupHosts(&mq, log)
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if mr != nil {
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b := bufpool.Get(4096)
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return mr.PackBuffer(*b)
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}
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// only cache for single question message.
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if len(mq.Question) == 1 {
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key := resolver_util.NewCacheKey(&mq.Question[0])
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mr = h.cache.Load(key)
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if mr != nil {
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log.Debugf("exchange message %d (cached): %s", mq.Id, mq.Question[0].String())
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mr.Id = mq.Id
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b := bufpool.Get(4096)
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return mr.PackBuffer(*b)
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}
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defer func() {
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if mr != nil {
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h.cache.Store(key, mr, h.md.ttl)
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}
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}()
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}
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b := bufpool.Get(4096)
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defer bufpool.Put(b)
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query, err := mq.PackBuffer(*b)
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if err != nil {
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log.Error(err)
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return nil, err
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}
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var reply []byte
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for _, ex := range h.exchangers {
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log.Debugf("exchange message %d via %s: %s", mq.Id, ex.String(), mq.Question[0].String())
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reply, err = ex.Exchange(ctx, query)
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if err == nil {
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break
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}
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log.Error(err)
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}
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if err != nil {
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return nil, err
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}
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mr = &dns.Msg{}
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if err = mr.Unpack(reply); err != nil {
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log.Error(err)
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return nil, err
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}
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return reply, nil
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}
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// lookup host mapper
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func (h *dnsHandler) lookupHosts(r *dns.Msg, log logger.Logger) (m *dns.Msg) {
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if h.hosts == nil ||
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r.Question[0].Qclass != dns.ClassINET ||
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(r.Question[0].Qtype != dns.TypeA && r.Question[0].Qtype != dns.TypeAAAA) {
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return nil
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}
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m = &dns.Msg{}
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m.SetReply(r)
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host := strings.TrimSuffix(r.Question[0].Name, ".")
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switch r.Question[0].Qtype {
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case dns.TypeA:
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ips, _ := h.hosts.Lookup("ip4", host)
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if len(ips) == 0 {
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return nil
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}
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log.Debugf("hit host mapper: %s -> %s", host, ips)
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for _, ip := range ips {
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rr, err := dns.NewRR(fmt.Sprintf("%s IN A %s\n", r.Question[0].Name, ip.String()))
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if err != nil {
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log.Error(err)
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return nil
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}
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m.Answer = append(m.Answer, rr)
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}
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case dns.TypeAAAA:
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ips, _ := h.hosts.Lookup("ip6", host)
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if len(ips) == 0 {
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return nil
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}
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log.Debugf("hit host mapper: %s -> %s", host, ips)
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for _, ip := range ips {
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rr, err := dns.NewRR(fmt.Sprintf("%s IN AAAA %s\n", r.Question[0].Name, ip.String()))
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if err != nil {
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log.Error(err)
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return nil
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}
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m.Answer = append(m.Answer, rr)
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}
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}
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return
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}
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func (h *dnsHandler) dumpMsgHeader(m *dns.Msg) string {
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buf := new(bytes.Buffer)
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buf.WriteString(m.MsgHdr.String() + " ")
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buf.WriteString("QUERY: " + strconv.Itoa(len(m.Question)) + ", ")
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buf.WriteString("ANSWER: " + strconv.Itoa(len(m.Answer)) + ", ")
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buf.WriteString("AUTHORITY: " + strconv.Itoa(len(m.Ns)) + ", ")
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buf.WriteString("ADDITIONAL: " + strconv.Itoa(len(m.Extra)))
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return buf.String()
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}
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41
handler/dns/metadata.go
Normal file
41
handler/dns/metadata.go
Normal file
@ -0,0 +1,41 @@
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package dns
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import (
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"net"
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"time"
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mdata "github.com/go-gost/gost/v3/pkg/metadata"
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)
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type metadata struct {
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readTimeout time.Duration
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ttl time.Duration
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timeout time.Duration
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clientIP net.IP
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// nameservers
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dns []string
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}
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func (h *dnsHandler) parseMetadata(md mdata.Metadata) (err error) {
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const (
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readTimeout = "readTimeout"
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ttl = "ttl"
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timeout = "timeout"
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clientIP = "clientIP"
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dns = "dns"
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)
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h.md.readTimeout = mdata.GetDuration(md, readTimeout)
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h.md.ttl = mdata.GetDuration(md, ttl)
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h.md.timeout = mdata.GetDuration(md, timeout)
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if h.md.timeout <= 0 {
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h.md.timeout = 5 * time.Second
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}
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sip := mdata.GetString(md, clientIP)
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if sip != "" {
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h.md.clientIP = net.ParseIP(sip)
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}
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h.md.dns = mdata.GetStrings(md, dns)
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return
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}
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