mirror of
https://github.com/SagerNet/sing.git
synced 2025-04-04 20:37:40 +03:00
420 lines
12 KiB
Go
420 lines
12 KiB
Go
package system
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import (
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"context"
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"net"
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"net/netip"
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"os"
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"github.com/sagernet/sing/common"
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"github.com/sagernet/sing/common/buf"
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"github.com/sagernet/sing/common/cache"
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E "github.com/sagernet/sing/common/exceptions"
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"github.com/sagernet/sing/common/log"
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M "github.com/sagernet/sing/common/metadata"
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N "github.com/sagernet/sing/common/network"
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"github.com/sagernet/sing/common/rw"
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"github.com/sagernet/sing/common/tun"
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"github.com/sagernet/sing/common/udpnat"
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"gvisor.dev/gvisor/pkg/tcpip"
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tcpipBuffer "gvisor.dev/gvisor/pkg/tcpip/buffer"
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"gvisor.dev/gvisor/pkg/tcpip/header"
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"gvisor.dev/gvisor/pkg/tcpip/header/parse"
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"gvisor.dev/gvisor/pkg/tcpip/stack"
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)
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var logger = log.NewLogger("tun <system>")
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type Stack struct {
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tunFd uintptr
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tunMtu int
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inetAddress netip.Prefix
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inet6Address netip.Prefix
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handler tun.Handler
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tunFile *os.File
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tcpForwarder *net.TCPListener
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tcpPort uint16
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tcpSessions *cache.LruCache[netip.AddrPort, netip.AddrPort]
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udpNat *udpnat.Service[netip.AddrPort]
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}
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func New(tunFd uintptr, tunMtu int, inetAddress netip.Prefix, inet6Address netip.Prefix, packetTimeout int64, handler tun.Handler) tun.Stack {
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return &Stack{
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tunFd: tunFd,
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tunMtu: tunMtu,
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inetAddress: inetAddress,
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inet6Address: inet6Address,
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handler: handler,
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tunFile: os.NewFile(tunFd, "tun"),
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tcpSessions: cache.New(
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cache.WithAge[netip.AddrPort, netip.AddrPort](packetTimeout),
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cache.WithUpdateAgeOnGet[netip.AddrPort, netip.AddrPort](),
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),
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udpNat: udpnat.New[netip.AddrPort](packetTimeout, handler),
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}
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}
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func (t *Stack) Start() error {
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var network string
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var address net.TCPAddr
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if !t.inet6Address.IsValid() {
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network = "tcp4"
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address.IP = t.inetAddress.Addr().AsSlice()
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} else {
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network = "tcp"
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address.IP = net.IPv6zero
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}
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tcpListener, err := net.ListenTCP(network, &address)
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if err != nil {
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return err
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}
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t.tcpForwarder = tcpListener
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go t.tcpLoop()
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go t.tunLoop()
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return nil
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}
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func (t *Stack) Close() error {
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t.tcpForwarder.Close()
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t.tunFile.Close()
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return nil
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}
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func (t *Stack) tunLoop() {
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_buffer := buf.Make(t.tunMtu)
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buffer := common.Dup(_buffer)
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for {
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n, err := t.tunFile.Read(buffer)
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if err != nil {
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t.handler.HandleError(err)
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break
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}
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packet := buffer[:n]
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t.deliverPacket(packet)
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}
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}
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func (t *Stack) deliverPacket(packet []byte) {
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var err error
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switch header.IPVersion(packet) {
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case header.IPv4Version:
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ipHdr := header.IPv4(packet)
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switch ipHdr.TransportProtocol() {
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case header.TCPProtocolNumber:
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err = t.processIPv4TCP(ipHdr, ipHdr.Payload())
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case header.UDPProtocolNumber:
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err = t.processIPv4UDP(ipHdr, ipHdr.Payload())
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default:
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_, err = t.tunFile.Write(packet)
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}
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case header.IPv6Version:
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pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
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Data: tcpipBuffer.View(packet).ToVectorisedView(),
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})
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proto, _, _, _, ok := parse.IPv6(pkt)
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pkt.DecRef()
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if !ok {
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return
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}
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ipHdr := header.IPv6(packet)
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switch proto {
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case header.TCPProtocolNumber:
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err = t.processIPv6TCP(ipHdr, ipHdr.Payload())
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case header.UDPProtocolNumber:
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err = t.processIPv6UDP(ipHdr, ipHdr.Payload())
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default:
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_, err = t.tunFile.Write(packet)
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}
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}
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if err != nil {
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t.handler.HandleError(err)
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}
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}
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func (t *Stack) processIPv4TCP(ipHdr header.IPv4, tcpHdr header.TCP) error {
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sourceAddress := ipHdr.SourceAddress()
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destinationAddress := ipHdr.DestinationAddress()
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sourcePort := tcpHdr.SourcePort()
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destinationPort := tcpHdr.DestinationPort()
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logger.Trace(sourceAddress, ":", sourcePort, " => ", destinationAddress, ":", destinationPort)
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if sourcePort != t.tcpPort {
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key := M.AddrPortFrom(net.IP(destinationAddress), sourcePort)
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t.tcpSessions.LoadOrStore(key, func() netip.AddrPort {
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return M.AddrPortFrom(net.IP(sourceAddress), destinationPort)
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})
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ipHdr.SetSourceAddress(destinationAddress)
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ipHdr.SetDestinationAddress(tcpip.Address(t.inetAddress.Addr().AsSlice()))
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tcpHdr.SetDestinationPort(t.tcpPort)
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} else {
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key := M.AddrPortFrom(net.IP(destinationAddress), destinationPort)
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session, loaded := t.tcpSessions.Load(key)
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if !loaded {
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return E.New("unknown tcp session with source port ", destinationPort, " to destination address ", destinationAddress)
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}
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ipHdr.SetSourceAddress(destinationAddress)
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tcpHdr.SetSourcePort(session.Port())
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ipHdr.SetDestinationAddress(tcpip.Address(session.Addr().AsSlice()))
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}
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ipHdr.SetChecksum(0)
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ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
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tcpHdr.SetChecksum(0)
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tcpHdr.SetChecksum(^tcpHdr.CalculateChecksum(header.ChecksumCombine(
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header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddress(), ipHdr.DestinationAddress(), uint16(len(tcpHdr))),
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header.Checksum(tcpHdr.Payload(), 0),
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)))
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_, err := t.tunFile.Write(ipHdr)
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return err
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}
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func (t *Stack) processIPv6TCP(ipHdr header.IPv6, tcpHdr header.TCP) error {
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sourceAddress := ipHdr.SourceAddress()
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destinationAddress := ipHdr.DestinationAddress()
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sourcePort := tcpHdr.SourcePort()
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destinationPort := tcpHdr.DestinationPort()
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if sourcePort != t.tcpPort {
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key := M.AddrPortFrom(net.IP(destinationAddress), sourcePort)
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t.tcpSessions.LoadOrStore(key, func() netip.AddrPort {
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return M.AddrPortFrom(net.IP(sourceAddress), destinationPort)
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})
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ipHdr.SetSourceAddress(destinationAddress)
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ipHdr.SetDestinationAddress(tcpip.Address(t.inet6Address.Addr().AsSlice()))
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tcpHdr.SetDestinationPort(t.tcpPort)
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} else {
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key := M.AddrPortFrom(net.IP(destinationAddress), destinationPort)
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session, loaded := t.tcpSessions.Load(key)
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if !loaded {
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return E.New("unknown tcp session with source port ", destinationPort, " to destination address ", destinationAddress)
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}
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ipHdr.SetSourceAddress(destinationAddress)
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tcpHdr.SetSourcePort(session.Port())
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ipHdr.SetDestinationAddress(tcpip.Address(session.Addr().AsSlice()))
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}
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tcpHdr.SetChecksum(0)
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tcpHdr.SetChecksum(^tcpHdr.CalculateChecksum(header.ChecksumCombine(
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header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddress(), ipHdr.DestinationAddress(), uint16(len(tcpHdr))),
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header.Checksum(tcpHdr.Payload(), 0),
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)))
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_, err := t.tunFile.Write(ipHdr)
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return err
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}
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func (t *Stack) tcpLoop() {
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for {
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logger.Trace("tcp start")
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tcpConn, err := t.tcpForwarder.AcceptTCP()
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logger.Trace("tcp accept")
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if err != nil {
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t.handler.HandleError(err)
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return
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}
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key := M.AddrPortFromNet(tcpConn.RemoteAddr())
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session, ok := t.tcpSessions.Load(key)
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if !ok {
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tcpConn.Close()
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logger.Warn("dropped unknown tcp session from ", key)
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continue
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}
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var metadata M.Metadata
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metadata.Protocol = "tun"
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metadata.Source.Addr = session.Addr()
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metadata.Source.Port = key.Port()
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metadata.Destination.Addr = key.Addr()
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metadata.Destination.Port = session.Port()
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go t.processConn(tcpConn, metadata, key)
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}
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}
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func (t *Stack) processConn(conn *net.TCPConn, metadata M.Metadata, key netip.AddrPort) {
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err := t.handler.NewConnection(context.Background(), conn, metadata)
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if err != nil {
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t.handler.HandleError(err)
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}
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t.tcpSessions.Delete(key)
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}
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func (t *Stack) processIPv4UDP(ipHdr header.IPv4, hdr header.UDP) error {
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var metadata M.Metadata
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metadata.Protocol = "tun"
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metadata.Source = M.SocksaddrFrom(net.IP(ipHdr.SourceAddress()), hdr.SourcePort())
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metadata.Source = M.SocksaddrFrom(net.IP(ipHdr.DestinationAddress()), hdr.DestinationPort())
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headerCache := buf.New()
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_, err := headerCache.Write(ipHdr[:ipHdr.HeaderLength()+header.UDPMinimumSize])
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if err != nil {
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return err
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}
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logger.Trace("[UDP] ", metadata.Source, "=>", metadata.Destination)
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t.udpNat.NewPacket(metadata.Source.AddrPort(), func() N.PacketWriter {
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return &inetPacketWriter{
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tun: t,
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headerCache: headerCache,
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sourceAddress: ipHdr.SourceAddress(),
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destination: ipHdr.DestinationAddress(),
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destinationPort: hdr.DestinationPort(),
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}
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}, buf.With(hdr), metadata)
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return nil
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}
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type inetPacketWriter struct {
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tun *Stack
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headerCache *buf.Buffer
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sourceAddress tcpip.Address
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destination tcpip.Address
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destinationPort uint16
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}
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func (w *inetPacketWriter) WritePacket(buffer *buf.Buffer, destination M.Socksaddr) error {
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index := w.headerCache.Len()
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newHeader := w.headerCache.Extend(w.headerCache.Len())
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copy(newHeader, w.headerCache.Bytes())
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w.headerCache.Advance(index)
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defer func() {
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w.headerCache.FullReset()
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w.headerCache.Resize(0, index)
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}()
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var newSourceAddress tcpip.Address
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var newSourcePort uint16
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if destination.IsValid() {
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newSourceAddress = tcpip.Address(destination.Addr.AsSlice())
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newSourcePort = destination.Port
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} else {
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newSourceAddress = w.destination
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newSourcePort = w.destinationPort
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}
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newIpHdr := header.IPv4(newHeader)
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newIpHdr.SetSourceAddress(newSourceAddress)
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newIpHdr.SetTotalLength(uint16(int(w.headerCache.Len()) + buffer.Len()))
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newIpHdr.SetChecksum(0)
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newIpHdr.SetChecksum(^newIpHdr.CalculateChecksum())
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udpHdr := header.UDP(w.headerCache.From(w.headerCache.Len() - header.UDPMinimumSize))
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udpHdr.SetSourcePort(newSourcePort)
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udpHdr.SetLength(uint16(header.UDPMinimumSize + buffer.Len()))
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udpHdr.SetChecksum(0)
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udpHdr.SetChecksum(^udpHdr.CalculateChecksum(header.Checksum(buffer.Bytes(), header.PseudoHeaderChecksum(header.UDPProtocolNumber, newSourceAddress, w.sourceAddress, uint16(header.UDPMinimumSize+buffer.Len())))))
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replyVV := tcpipBuffer.VectorisedView{}
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replyVV.AppendView(newHeader)
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replyVV.AppendView(buffer.Bytes())
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return w.tun.WriteVV(replyVV)
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}
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func (w *inetPacketWriter) Close() error {
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w.headerCache.Release()
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return nil
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}
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func (t *Stack) processIPv6UDP(ipHdr header.IPv6, hdr header.UDP) error {
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var metadata M.Metadata
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metadata.Protocol = "tun"
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metadata.Source = M.SocksaddrFrom(net.IP(ipHdr.SourceAddress()), hdr.SourcePort())
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metadata.Destination = M.SocksaddrFrom(net.IP(ipHdr.DestinationAddress()), hdr.DestinationPort())
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headerCache := buf.New()
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_, err := headerCache.Write(ipHdr[:uint16(len(ipHdr))-ipHdr.PayloadLength()+header.UDPMinimumSize])
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if err != nil {
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return err
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}
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t.udpNat.NewPacket(metadata.Source.AddrPort(), func() N.PacketWriter {
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return &inet6PacketWriter{
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tun: t,
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headerCache: headerCache,
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sourceAddress: ipHdr.SourceAddress(),
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destination: ipHdr.DestinationAddress(),
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destinationPort: hdr.DestinationPort(),
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}
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}, buf.With(hdr), metadata)
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return nil
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}
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type inet6PacketWriter struct {
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tun *Stack
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headerCache *buf.Buffer
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sourceAddress tcpip.Address
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destination tcpip.Address
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destinationPort uint16
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}
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func (w *inet6PacketWriter) WritePacket(buffer *buf.Buffer, destination M.Socksaddr) error {
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index := w.headerCache.Len()
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newHeader := w.headerCache.Extend(w.headerCache.Len())
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copy(newHeader, w.headerCache.Bytes())
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w.headerCache.Advance(index)
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defer func() {
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w.headerCache.FullReset()
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w.headerCache.Resize(0, index)
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}()
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var newSourceAddress tcpip.Address
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var newSourcePort uint16
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if destination.IsValid() {
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newSourceAddress = tcpip.Address(destination.Addr.AsSlice())
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newSourcePort = destination.Port
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} else {
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newSourceAddress = w.destination
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newSourcePort = w.destinationPort
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}
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newIpHdr := header.IPv6(newHeader)
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newIpHdr.SetSourceAddress(newSourceAddress)
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newIpHdr.SetPayloadLength(uint16(header.UDPMinimumSize + buffer.Len()))
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udpHdr := header.UDP(w.headerCache.From(w.headerCache.Len() - header.UDPMinimumSize))
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udpHdr.SetSourcePort(newSourcePort)
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udpHdr.SetLength(uint16(header.UDPMinimumSize + buffer.Len()))
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udpHdr.SetChecksum(0)
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udpHdr.SetChecksum(^udpHdr.CalculateChecksum(header.Checksum(buffer.Bytes(), header.PseudoHeaderChecksum(header.UDPProtocolNumber, newSourceAddress, w.sourceAddress, uint16(header.UDPMinimumSize+buffer.Len())))))
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replyVV := tcpipBuffer.VectorisedView{}
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replyVV.AppendView(newHeader)
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replyVV.AppendView(buffer.Bytes())
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return w.tun.WriteVV(replyVV)
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}
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func (t *Stack) WriteVV(vv tcpipBuffer.VectorisedView) error {
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data := make([][]byte, 0, len(vv.Views()))
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for _, view := range vv.Views() {
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data = append(data, view)
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}
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return common.Error(rw.WriteV(t.tunFd, data...))
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}
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func (w *inet6PacketWriter) Close() error {
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w.headerCache.Release()
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return nil
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}
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type tcpipError struct {
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Err tcpip.Error
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}
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func (e *tcpipError) Error() string {
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return e.Err.String()
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}
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