mirror of
https://github.com/MetaCubeX/mihomo.git
synced 2024-07-07 13:27:49 +00:00
203 lines
5.1 KiB
Go
203 lines
5.1 KiB
Go
package sing_tun
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import (
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"context"
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"encoding/binary"
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"io"
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"net"
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"net/netip"
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"sync"
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"time"
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"github.com/metacubex/mihomo/common/pool"
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"github.com/metacubex/mihomo/component/resolver"
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"github.com/metacubex/mihomo/listener/sing"
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"github.com/metacubex/mihomo/log"
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D "github.com/miekg/dns"
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"github.com/sagernet/sing/common/buf"
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"github.com/sagernet/sing/common/bufio"
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M "github.com/sagernet/sing/common/metadata"
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"github.com/sagernet/sing/common/network"
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)
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const DefaultDnsReadTimeout = time.Second * 10
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const DefaultDnsRelayTimeout = time.Second * 5
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type ListenerHandler struct {
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*sing.ListenerHandler
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DnsAdds []netip.AddrPort
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}
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func (h *ListenerHandler) ShouldHijackDns(targetAddr netip.AddrPort) bool {
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if targetAddr.Addr().IsLoopback() && targetAddr.Port() == 53 { // cause by system stack
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return true
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}
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for _, addrPort := range h.DnsAdds {
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if addrPort == targetAddr || (addrPort.Addr().IsUnspecified() && targetAddr.Port() == 53) {
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return true
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}
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}
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return false
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}
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func (h *ListenerHandler) NewConnection(ctx context.Context, conn net.Conn, metadata M.Metadata) error {
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if h.ShouldHijackDns(metadata.Destination.AddrPort()) {
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log.Debugln("[DNS] hijack tcp:%s", metadata.Destination.String())
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buff := pool.Get(pool.UDPBufferSize)
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defer func() {
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_ = pool.Put(buff)
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_ = conn.Close()
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}()
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for {
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if conn.SetReadDeadline(time.Now().Add(DefaultDnsReadTimeout)) != nil {
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break
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}
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length := uint16(0)
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if err := binary.Read(conn, binary.BigEndian, &length); err != nil {
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break
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}
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if int(length) > len(buff) {
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break
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}
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n, err := io.ReadFull(conn, buff[:length])
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if err != nil {
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break
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}
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err = func() error {
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ctx, cancel := context.WithTimeout(ctx, DefaultDnsRelayTimeout)
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defer cancel()
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inData := buff[:n]
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msg, err := RelayDnsPacket(ctx, inData, buff)
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if err != nil {
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return err
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}
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err = binary.Write(conn, binary.BigEndian, uint16(len(msg)))
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if err != nil {
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return err
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}
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_, err = conn.Write(msg)
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if err != nil {
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return err
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}
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return nil
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}()
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if err != nil {
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return err
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}
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}
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return nil
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}
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return h.ListenerHandler.NewConnection(ctx, conn, metadata)
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}
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const SafeDnsPacketSize = 2 * 1024 // safe size which is 1232 from https://dnsflagday.net/2020/, so 2048 is enough
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func (h *ListenerHandler) NewPacketConnection(ctx context.Context, conn network.PacketConn, metadata M.Metadata) error {
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if h.ShouldHijackDns(metadata.Destination.AddrPort()) {
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log.Debugln("[DNS] hijack udp:%s from %s", metadata.Destination.String(), metadata.Source.String())
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defer func() { _ = conn.Close() }()
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mutex := sync.Mutex{}
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conn2 := conn // a new interface to set nil in defer
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defer func() {
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mutex.Lock() // this goroutine must exit after all conn.WritePacket() is not running
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defer mutex.Unlock()
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conn2 = nil
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}()
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rwOptions := network.ReadWaitOptions{
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FrontHeadroom: network.CalculateFrontHeadroom(conn),
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RearHeadroom: network.CalculateRearHeadroom(conn),
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MTU: SafeDnsPacketSize,
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}
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readWaiter, isReadWaiter := bufio.CreatePacketReadWaiter(conn)
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if isReadWaiter {
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readWaiter.InitializeReadWaiter(rwOptions)
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}
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for {
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var (
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readBuff *buf.Buffer
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dest M.Socksaddr
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err error
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)
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_ = conn.SetReadDeadline(time.Now().Add(DefaultDnsReadTimeout))
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readBuff = nil // clear last loop status, avoid repeat release
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if isReadWaiter {
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readBuff, dest, err = readWaiter.WaitReadPacket()
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} else {
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readBuff = rwOptions.NewPacketBuffer()
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dest, err = conn.ReadPacket(readBuff)
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if readBuff != nil {
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rwOptions.PostReturn(readBuff)
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}
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}
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if err != nil {
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if readBuff != nil {
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readBuff.Release()
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}
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if sing.ShouldIgnorePacketError(err) {
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break
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}
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return err
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}
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go func() {
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ctx, cancel := context.WithTimeout(ctx, DefaultDnsRelayTimeout)
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defer cancel()
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inData := readBuff.Bytes()
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writeBuff := readBuff
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writeBuff.Resize(writeBuff.Start(), 0)
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if len(writeBuff.FreeBytes()) < SafeDnsPacketSize { // only create a new buffer when space don't enough
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writeBuff = rwOptions.NewPacketBuffer()
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}
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msg, err := RelayDnsPacket(ctx, inData, writeBuff.FreeBytes())
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if writeBuff != readBuff {
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readBuff.Release()
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}
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if err != nil {
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writeBuff.Release()
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return
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}
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writeBuff.Truncate(len(msg))
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mutex.Lock()
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defer mutex.Unlock()
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conn := conn2
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if conn == nil {
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writeBuff.Release()
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return
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}
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err = conn.WritePacket(writeBuff, dest) // WritePacket will release writeBuff
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if err != nil {
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writeBuff.Release()
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return
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}
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}()
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}
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return nil
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}
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return h.ListenerHandler.NewPacketConnection(ctx, conn, metadata)
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}
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func RelayDnsPacket(ctx context.Context, payload []byte, target []byte) ([]byte, error) {
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msg := &D.Msg{}
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if err := msg.Unpack(payload); err != nil {
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return nil, err
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}
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r, err := resolver.ServeMsg(ctx, msg)
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if err != nil {
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m := new(D.Msg)
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m.SetRcode(msg, D.RcodeServerFailure)
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return m.PackBuffer(target)
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}
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r.SetRcode(msg, r.Rcode)
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r.Compress = true
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return r.PackBuffer(target)
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}
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