rename vtun to tungo

2025-07-26 16:17:04 +08:00
parent 281295d02f
commit 35a049fb03
30 changed files with 801 additions and 307 deletions
@@ -0,0 +1,147 @@
+package tungo
+
+import (
+	"context"
+	"io"
+	"sync"
+
+	"github.com/go-gost/core/logger"
+	"gvisor.dev/gvisor/pkg/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
+
+const (
+	// Queue length for outbound packet, arriving for read. Overflow
+	// causes packet drops.
+	defaultOutQueueLen = 1 << 10
+)
+
+// Endpoint implements the interface of stack.LinkEndpoint from io.ReadWriter.
+type endpoint struct {
+	*channel.Endpoint
+
+	// rw is the io.ReadWriter for reading and writing packets.
+	rw io.ReadWriter
+
+	// mtu (maximum transmission unit) is the maximum size of a packet.
+	mtu uint32
+
+	// offset can be useful when perform TUN device I/O with TUN_PI enabled.
+	offset int
+
+	// once is used to perform the init action once when attaching.
+	once sync.Once
+
+	// wg keeps track of running goroutines.
+	wg sync.WaitGroup
+
+	log logger.Logger
+}
+
+// New returns stack.LinkEndpoint(.*Endpoint) and error.
+func newEndpoint(rw io.ReadWriter, mtu int, log logger.Logger) *endpoint {
+	return &endpoint{
+		Endpoint: channel.New(defaultOutQueueLen, uint32(mtu), ""),
+		rw:       rw,
+		mtu:      uint32(mtu),
+		log:      log,
+	}
+}
+
+// Attach launches the goroutine that reads packets from io.Reader and
+// dispatches them via the provided dispatcher.
+func (e *endpoint) Attach(dispatcher stack.NetworkDispatcher) {
+	e.Endpoint.Attach(dispatcher)
+	e.once.Do(func() {
+		ctx, cancel := context.WithCancel(context.Background())
+		e.wg.Add(2)
+		go func() {
+			e.outboundLoop(ctx)
+			e.wg.Done()
+		}()
+		go func() {
+			e.dispatchLoop(cancel)
+			e.wg.Done()
+		}()
+	})
+}
+
+func (e *endpoint) Wait() {
+	e.wg.Wait()
+}
+
+// dispatchLoop dispatches packets to upper layer.
+func (e *endpoint) dispatchLoop(cancel context.CancelFunc) {
+	// Call cancel() to ensure (*Endpoint).outboundLoop(context.Context) exits
+	// gracefully after (*Endpoint).dispatchLoop(context.CancelFunc) returns.
+	defer cancel()
+
+	offset, mtu := e.offset, int(e.mtu)
+
+	for {
+		data := make([]byte, offset+mtu)
+
+		n, err := e.rw.Read(data)
+		if err != nil {
+			e.log.Error(err)
+			break
+		}
+
+		if e.log.IsLevelEnabled(logger.TraceLevel) {
+			e.log.Tracef("read: (%d) % x", n, data[:n])
+		}
+
+		if n == 0 || n > mtu {
+			continue
+		}
+
+		if !e.IsAttached() {
+			continue /* unattached, drop packet */
+		}
+
+		pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
+			Payload: buffer.MakeWithData(data[offset : offset+n]),
+		})
+
+		switch header.IPVersion(data[offset:]) {
+		case header.IPv4Version:
+			e.InjectInbound(header.IPv4ProtocolNumber, pkt)
+		case header.IPv6Version:
+			e.InjectInbound(header.IPv6ProtocolNumber, pkt)
+		}
+		pkt.DecRef()
+	}
+}
+
+// outboundLoop reads outbound packets from channel, and then it calls
+// writePacket to send those packets back to lower layer.
+func (e *endpoint) outboundLoop(ctx context.Context) {
+	for {
+		pkt := e.ReadContext(ctx)
+		if pkt == nil {
+			break
+		}
+		e.writePacket(pkt)
+	}
+}
+
+// writePacket writes outbound packets to the io.Writer.
+func (e *endpoint) writePacket(pkt *stack.PacketBuffer) tcpip.Error {
+	defer pkt.DecRef()
+
+	buf := pkt.ToBuffer()
+	defer buf.Release()
+	if e.offset != 0 {
+		v := buffer.NewViewWithData(make([]byte, e.offset))
+		_ = buf.Prepend(v)
+	}
+
+	if _, err := e.rw.Write(buf.Flatten()); err != nil {
+		return &tcpip.ErrInvalidEndpointState{}
+	}
+
+	return nil
+}