Be more like a library to support mobile (#247)

tun_ios.go

@@ -0,0 +1,105 @@
+// +build ios
+
+package nebula
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"os"
+	"sync"
+	"syscall"
+)
+
+type Tun struct {
+	io.ReadWriteCloser
+	Device string
+	Cidr   *net.IPNet
+}
+
+func newTun(deviceName string, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int) (ifce *Tun, err error) {
+	return nil, fmt.Errorf("newTun not supported in iOS")
+}
+
+func newTunFromFd(deviceFd int, cidr *net.IPNet, defaultMTU int, routes []route, unsafeRoutes []route, txQueueLen int) (ifce *Tun, err error) {
+	if len(routes) > 0 {
+		return nil, fmt.Errorf("route MTU not supported in Darwin")
+	}
+
+	file := os.NewFile(uintptr(deviceFd), "/dev/tun")
+	ifce = &Tun{
+		Cidr:            cidr,
+		ReadWriteCloser: &tunReadCloser{f: file},
+	}
+	return
+}
+
+func (c *Tun) Activate() error {
+	c.Device = "iOS"
+	return nil
+}
+
+func (c *Tun) WriteRaw(b []byte) error {
+	_, err := c.Write(b)
+	return err
+}
+
+// The following is hoisted up from water, we do this so we can inject our own fd on iOS
+type tunReadCloser struct {
+	f io.ReadWriteCloser
+
+	rMu  sync.Mutex
+	rBuf []byte
+
+	wMu  sync.Mutex
+	wBuf []byte
+}
+
+func (t *tunReadCloser) Read(to []byte) (int, error) {
+	t.rMu.Lock()
+	defer t.rMu.Unlock()
+
+	if cap(t.rBuf) < len(to)+4 {
+		t.rBuf = make([]byte, len(to)+4)
+	}
+	t.rBuf = t.rBuf[:len(to)+4]
+
+	n, err := t.f.Read(t.rBuf)
+	copy(to, t.rBuf[4:])
+	return n - 4, err
+}
+
+func (t *tunReadCloser) Write(from []byte) (int, error) {
+
+	if len(from) == 0 {
+		return 0, syscall.EIO
+	}
+
+	t.wMu.Lock()
+	defer t.wMu.Unlock()
+
+	if cap(t.wBuf) < len(from)+4 {
+		t.wBuf = make([]byte, len(from)+4)
+	}
+	t.wBuf = t.wBuf[:len(from)+4]
+
+	// Determine the IP Family for the NULL L2 Header
+	ipVer := from[0] >> 4
+	if ipVer == 4 {
+		t.wBuf[3] = syscall.AF_INET
+	} else if ipVer == 6 {
+		t.wBuf[3] = syscall.AF_INET6
+	} else {
+		return 0, errors.New("unable to determine IP version from packet")
+	}
+
+	copy(t.wBuf[4:], from)
+
+	n, err := t.f.Write(t.wBuf)
+	return n - 4, err
+}
+
+func (t *tunReadCloser) Close() error {
+	return t.f.Close()
+}