Clash.Meta/listener/tproxy/packet.go

121 lines
3.3 KiB
Go

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