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tcp.go
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tcp.go
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// Copyright (C) 2020-2021, IrineSistiana
//
// This file is part of mosdns.
//
// mosdns is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// mosdns is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package server
import (
"context"
"crypto/tls"
"errors"
"fmt"
"github.com/IrineSistiana/mosdns/dispatcher/handler"
"github.com/IrineSistiana/mosdns/dispatcher/pkg/dnsutils"
"github.com/miekg/dns"
"go.uber.org/zap"
"net"
"time"
)
const (
serverTCPWriteTimeout = time.Second
)
type tcpResponseWriter struct {
c net.Conn
}
func (t *tcpResponseWriter) Write(m *dns.Msg) (n int, err error) {
t.c.SetWriteDeadline(time.Now().Add(serverTCPWriteTimeout))
return dnsutils.WriteMsgToTCP(t.c, m)
}
func (s *Server) startTCP() error {
if s.Listener == nil {
return errors.New("tcp server has a nil listener")
}
l := s.Listener
isDoT := s.Protocol == ProtocolDoT
if isDoT {
if err := checkTLSConfig(s.TLSConfig); err != nil {
return err
}
l = tls.NewListener(l, s.TLSConfig)
}
listenerCtx, cancel := context.WithCancel(context.Background())
defer cancel()
for {
c, err := l.Accept()
if err != nil {
netErr, ok := err.(net.Error)
if ok && netErr.Temporary() {
s.logger.Warn("listener temporary err", zap.Error(err))
time.Sleep(time.Second * 5)
continue
} else {
return fmt.Errorf("unexpected listener err: %w", err)
}
}
tcpConnCtx, cancelConn := context.WithCancel(listenerCtx)
go func() {
defer c.Close()
defer cancelConn()
for {
c.SetReadDeadline(time.Now().Add(s.idleTimeout()))
q, _, err := dnsutils.ReadMsgFromTCP(c)
if err != nil {
return // read err, close the connection
}
go func() {
qCtx := handler.NewContext(q, c.RemoteAddr())
qCtx.SetTCPClient(true)
s.handleQueryTimeout(tcpConnCtx, qCtx, &tcpResponseWriter{c: c})
}()
}
}()
}
}