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tcp.go
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tcp.go
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// Copyright (C) 2020, 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/utils"
"github.com/miekg/dns"
"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 utils.WriteMsgToTCP(t.c, m)
}
func (s *Server) serveTCP(isDoT bool) error {
l, err := net.Listen("tcp", s.Config.Addr)
if err != nil {
return err
}
s.l.Lock()
s.listener = l
s.l.Unlock()
defer func() {
s.l.Lock()
l.Close()
s.l.Unlock()
}()
if isDoT {
if len(s.Config.Cert) == 0 || len(s.Config.Key) == 0 {
return errors.New("dot server needs cert and key")
}
tlsConfig := new(tls.Config)
tlsConfig.Certificates = make([]tls.Certificate, 1)
tlsConfig.Certificates[0], err = tls.LoadX509KeyPair(s.Config.Cert, s.Config.Key)
if err != nil {
return err
}
l = tls.NewListener(l, tlsConfig)
}
listenerCtx, cancel := context.WithCancel(context.Background())
defer cancel()
for {
c, err := l.Accept()
if err != nil {
if s.isDone() {
return nil
}
netErr, ok := err.(net.Error)
if ok && netErr.Temporary() {
s.Logger.Warnf("listener: temporary err: %v", err)
time.Sleep(time.Second * 5)
continue
} else {
return fmt.Errorf("unexpected listener err: %w", err)
}
}
tcpConnCtx, cancel := context.WithCancel(listenerCtx)
go func() {
defer c.Close()
defer cancel()
for {
c.SetReadDeadline(time.Now().Add(s.idleTimeout))
q, _, err := utils.ReadMsgFromTCP(c)
if err != nil {
return // read err, close the conn
}
w := &tcpResponseWriter{c: c}
qCtx := handler.NewContext(q)
qCtx.From = c.RemoteAddr()
ctx, cancel := context.WithTimeout(tcpConnCtx, s.queryTimeout)
go func() {
defer cancel()
s.Handler.ServeDNS(ctx, qCtx, w)
}()
}
}()
}
}