mirror of
https://github.com/SagerNet/sing-tun.git
synced 2025-09-27 04:55:53 +08:00
96 lines
3.4 KiB
Go
96 lines
3.4 KiB
Go
//go:build with_gvisor
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package tun
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import (
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"context"
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"errors"
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"net/netip"
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"github.com/sagernet/gvisor/pkg/tcpip"
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"github.com/sagernet/gvisor/pkg/tcpip/header"
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"github.com/sagernet/gvisor/pkg/tcpip/stack"
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"github.com/sagernet/gvisor/pkg/tcpip/transport/tcp"
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"github.com/sagernet/sing-tun/internal/gtcpip/checksum"
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"github.com/sagernet/sing/common"
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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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)
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type TCPForwarder struct {
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ctx context.Context
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stack *stack.Stack
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handler Handler
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inet4LoopbackAddress []tcpip.Address
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inet6LoopbackAddress []tcpip.Address
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tun GVisorTun
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forwarder *tcp.Forwarder
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}
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func NewTCPForwarder(ctx context.Context, stack *stack.Stack, handler Handler) *TCPForwarder {
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return NewTCPForwarderWithLoopback(ctx, stack, handler, nil, nil, nil)
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}
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func NewTCPForwarderWithLoopback(ctx context.Context, stack *stack.Stack, handler Handler, inet4LoopbackAddress []netip.Addr, inet6LoopbackAddress []netip.Addr, tun GVisorTun) *TCPForwarder {
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forwarder := &TCPForwarder{
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ctx: ctx,
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stack: stack,
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handler: handler,
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inet4LoopbackAddress: common.Map(inet4LoopbackAddress, AddressFromAddr),
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inet6LoopbackAddress: common.Map(inet6LoopbackAddress, AddressFromAddr),
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tun: tun,
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}
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forwarder.forwarder = tcp.NewForwarder(stack, 0, 1024, forwarder.Forward)
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return forwarder
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}
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func (f *TCPForwarder) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketBuffer) bool {
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for _, inet4LoopbackAddress := range f.inet4LoopbackAddress {
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if id.LocalAddress == inet4LoopbackAddress {
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ipHdr := pkt.Network().(header.IPv4)
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ipHdr.SetDestinationAddressWithChecksumUpdate(ipHdr.SourceAddress())
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ipHdr.SetSourceAddressWithChecksumUpdate(inet4LoopbackAddress)
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tcpHdr := header.TCP(pkt.TransportHeader().Slice())
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tcpHdr.SetChecksum(0)
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tcpHdr.SetChecksum(^checksum.Checksum(tcpHdr.Payload(), tcpHdr.CalculateChecksum(
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header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddress(), ipHdr.DestinationAddress(), ipHdr.PayloadLength()),
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)))
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f.tun.WritePacket(pkt)
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return true
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}
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}
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for _, inet6LoopbackAddress := range f.inet6LoopbackAddress {
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if id.LocalAddress == inet6LoopbackAddress {
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ipHdr := pkt.Network().(header.IPv6)
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ipHdr.SetDestinationAddress(ipHdr.SourceAddress())
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ipHdr.SetSourceAddress(inet6LoopbackAddress)
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tcpHdr := header.TCP(pkt.TransportHeader().Slice())
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tcpHdr.SetChecksum(0)
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tcpHdr.SetChecksum(^checksum.Checksum(tcpHdr.Payload(), tcpHdr.CalculateChecksum(
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header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddress(), ipHdr.DestinationAddress(), ipHdr.PayloadLength()),
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)))
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f.tun.WritePacket(pkt)
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return true
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}
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}
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return f.forwarder.HandlePacket(id, pkt)
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}
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func (f *TCPForwarder) Forward(r *tcp.ForwarderRequest) {
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source := M.SocksaddrFrom(AddrFromAddress(r.ID().RemoteAddress), r.ID().RemotePort)
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destination := M.SocksaddrFrom(AddrFromAddress(r.ID().LocalAddress), r.ID().LocalPort)
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_, pErr := f.handler.PrepareConnection(N.NetworkTCP, source, destination, nil)
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if pErr != nil {
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r.Complete(!errors.Is(pErr, ErrDrop))
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return
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}
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conn := &gLazyConn{
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parentCtx: f.ctx,
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stack: f.stack,
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request: r,
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localAddr: source.TCPAddr(),
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remoteAddr: destination.TCPAddr(),
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}
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go f.handler.NewConnectionEx(f.ctx, conn, source, destination, nil)
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}
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