diff --git a/syscalls_darwin.go b/syscalls_darwin.go index 4f53283..260d2cb 100644 --- a/syscalls_darwin.go +++ b/syscalls_darwin.go @@ -5,7 +5,9 @@ package water import ( "errors" "fmt" + "io" "os" + "sync" "syscall" "unsafe" ) @@ -112,12 +114,68 @@ func newTUN(string) (ifce *Interface, err error) { } return &Interface{ - isTAP: false, - name: string(ifName.name[:ifNameSize-1 /* -1 is for \0 */]), - ReadWriteCloser: os.NewFile(uintptr(fd), string(ifName.name[:])), + isTAP: false, + name: string(ifName.name[:ifNameSize-1 /* -1 is for \0 */]), + ReadWriteCloser: &tunReadCloser{ + f: os.NewFile(uintptr(fd), string(ifName.name[:])), + }, }, nil } +// tunReadCloser is a hack to work around the first 4 bytes "packet +// information" because there doesn't seem to be an IFF_NO_PI for darwin. +type tunReadCloser struct { + f io.ReadWriteCloser + + rMu sync.Mutex + rBuf []byte + + wMu sync.Mutex + wBuf []byte +} + +var _ io.ReadWriteCloser = (*tunReadCloser)(nil) + +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) { + 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] + + t.wBuf[0] = 2 // Family: IP (2) + copy(t.wBuf[4:], from) + + n, err := t.f.Write(t.wBuf) + return n - 4, err +} + +func (t *tunReadCloser) Close() error { + // lock to make sure no read/write is in process. + t.rMu.Lock() + defer t.rMu.Unlock() + t.wMu.Lock() + defer t.wMu.Unlock() + + return t.f.Close() +} + func newTAP(ifName string) (ifce *Interface, err error) { return nil, errors.New("tap interface not implemented on this platform") }