120 lines
3.3 KiB
Go
120 lines
3.3 KiB
Go
package tproxy
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import (
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"errors"
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"fmt"
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"net"
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"net/netip"
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"github.com/Dreamacro/clash/adapter/inbound"
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"github.com/Dreamacro/clash/common/pool"
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C "github.com/Dreamacro/clash/constant"
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"github.com/Dreamacro/clash/log"
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)
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type packet struct {
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pc net.PacketConn
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lAddr netip.AddrPort
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buf []byte
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in chan<- C.PacketAdapter
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natTable C.NatTable
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}
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func (c *packet) Data() []byte {
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return c.buf
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}
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// WriteBack opens a new socket binding `addr` to write UDP packet back
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func (c *packet) WriteBack(b []byte, addr net.Addr) (n int, err error) {
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tc, err := createOrGetLocalConn(addr, c.LocalAddr(), c.in, c.natTable)
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if err != nil {
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n = 0
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return
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}
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n, err = tc.Write(b)
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return
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}
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// LocalAddr returns the source IP/Port of UDP Packet
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func (c *packet) LocalAddr() net.Addr {
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return &net.UDPAddr{IP: c.lAddr.Addr().AsSlice(), Port: int(c.lAddr.Port()), Zone: c.lAddr.Addr().Zone()}
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}
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func (c *packet) Drop() {
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pool.Put(c.buf)
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}
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func (c *packet) InAddr() net.Addr {
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return c.pc.LocalAddr()
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}
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// this function listen at rAddr and write to lAddr
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// for here, rAddr is the ip/port client want to access
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// lAddr is the ip/port client opened
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func createOrGetLocalConn(rAddr, lAddr net.Addr, in chan<- C.PacketAdapter, natTable C.NatTable) (*net.UDPConn, error) {
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remote := rAddr.String()
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local := lAddr.String()
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localConn := natTable.GetLocalConn(local, remote)
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// localConn not exist
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if localConn == nil {
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lockKey := remote + "-lock"
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cond, loaded := natTable.GetOrCreateLockForLocalConn(local, lockKey)
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if loaded {
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cond.L.Lock()
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cond.Wait()
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// we should get localConn here
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localConn = natTable.GetLocalConn(local, remote)
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if localConn == nil {
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return nil, fmt.Errorf("localConn is nil, nat entry not exist")
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}
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cond.L.Unlock()
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} else {
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if cond == nil {
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return nil, fmt.Errorf("cond is nil, nat entry not exist")
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}
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defer func() {
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natTable.DeleteLocalConnMap(local, lockKey)
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cond.Broadcast()
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}()
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conn, err := listenLocalConn(rAddr, lAddr, in, natTable)
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if err != nil {
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log.Errorln("listenLocalConn failed with error: %s, packet loss", err.Error())
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return nil, err
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}
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natTable.AddLocalConn(local, remote, conn)
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localConn = conn
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}
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}
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return localConn, nil
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}
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// this function listen at rAddr
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// and send what received to program itself, then send to real remote
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func listenLocalConn(rAddr, lAddr net.Addr, in chan<- C.PacketAdapter, natTable C.NatTable) (*net.UDPConn, error) {
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additions := []inbound.Addition{
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inbound.WithInName("DEFAULT-TPROXY"),
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inbound.WithSpecialRules(""),
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}
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lc, err := dialUDP("udp", rAddr.(*net.UDPAddr).AddrPort(), lAddr.(*net.UDPAddr).AddrPort())
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if err != nil {
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return nil, err
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}
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go func() {
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log.Debugln("TProxy listenLocalConn rAddr=%s lAddr=%s", rAddr.String(), lAddr.String())
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for {
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buf := pool.Get(pool.UDPBufferSize)
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br, err := lc.Read(buf)
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if err != nil {
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pool.Put(buf)
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if errors.Is(err, net.ErrClosed) {
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log.Debugln("TProxy local conn listener exit.. rAddr=%s lAddr=%s", rAddr.String(), lAddr.String())
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return
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}
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}
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// since following localPackets are pass through this socket which listen rAddr
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// I choose current listener as packet's packet conn
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handlePacketConn(lc, in, natTable, buf[:br], lAddr.(*net.UDPAddr).AddrPort(), rAddr.(*net.UDPAddr).AddrPort(), additions...)
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}
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}()
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return lc, nil
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}
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