Move all of tun into overlay (#577)

overlay/tun_android.go

@@ -0,0 +1,86 @@
+//go:build !e2e_testing
+// +build !e2e_testing
+
+package overlay
+
+import (
+	"fmt"
+	"io"
+	"net"
+	"os"
+
+	"github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+type Tun struct {
+	io.ReadWriteCloser
+	fd           int
+	Device       string
+	Cidr         *net.IPNet
+	MaxMTU       int
+	DefaultMTU   int
+	TXQueueLen   int
+	Routes       []Route
+	UnsafeRoutes []Route
+	l            *logrus.Logger
+}
+
+func newTunFromFd(l *logrus.Logger, deviceFd int, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int) (ifce *Tun, err error) {
+	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
+
+	ifce = &Tun{
+		ReadWriteCloser: file,
+		fd:              int(file.Fd()),
+		Device:          "android",
+		Cidr:            cidr,
+		DefaultMTU:      defaultMTU,
+		TXQueueLen:      txQueueLen,
+		Routes:          routes,
+		UnsafeRoutes:    unsafeRoutes,
+		l:               l,
+	}
+	return
+}
+
+func newTun(l *logrus.Logger, deviceName string, cidr *net.IPNet, defaultMTU int, routes []Route, unsafeRoutes []Route, txQueueLen int, multiqueue bool) (ifce *Tun, err error) {
+	return nil, fmt.Errorf("newTun not supported in Android")
+}
+
+func (c *Tun) WriteRaw(b []byte) error {
+	var nn int
+	for {
+		max := len(b)
+		n, err := unix.Write(c.fd, b[nn:max])
+		if n > 0 {
+			nn += n
+		}
+		if nn == len(b) {
+			return err
+		}
+
+		if err != nil {
+			return err
+		}
+
+		if n == 0 {
+			return io.ErrUnexpectedEOF
+		}
+	}
+}
+
+func (c Tun) Activate() error {
+	return nil
+}
+
+func (c *Tun) CidrNet() *net.IPNet {
+	return c.Cidr
+}
+
+func (c *Tun) DeviceName() string {
+	return c.Device
+}
+
+func (t *Tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+	return nil, fmt.Errorf("TODO: multiqueue not implemented for android")
+}