ReadBatch is named Read now

interface.go

@@ -350,7 +350,7 @@ func (f *Interface) listenIn(reader overlay.Queue, i int) {
 	conntrackCache := firewall.NewConntrackCacheTicker(f.conntrackCacheTimeout)
 
 	for {
-		pkts, err := reader.ReadBatch()
+		pkts, err := reader.Read()
 		if err != nil {
 			if !f.closed.Load() {
 				f.l.WithError(err).WithField("reader", i).Error("Error while reading outbound packet, closing")

overlay/device.go

@@ -7,18 +7,27 @@ import (
 	"github.com/slackhq/nebula/routing"
 )
 
-// defaultBatchBufSize is the per-Queue scratch size for ReadBatch on backends
+// defaultBatchBufSize is the per-Queue scratch size for Read on backends
 // that don't do TSO segmentation. 65535 covers any single IP packet.
 const defaultBatchBufSize = 65535
 
-// Queue is a readable/writable tun queue. ReadBatch returns one or more
-// packets; the returned slices are borrowed from the queue's internal buffer
-// and are only valid until the next ReadBatch / Read / Close on this Queue.
-// Callers must encrypt or copy each slice before the next call. Not safe for
-// concurrent use — one goroutine per Queue.
+// Queue is a readable/writable tun queue. One Queue is driven by a single
+// read goroutine plus concurrent writers (see Write / WriteReject below).
 type Queue interface {
-	io.ReadWriteCloser
-	ReadBatch() ([][]byte, error)
+	io.Closer
+
+	// Read returns one or more packets. The returned slices are borrowed
+	// from the Queue's internal buffer and are only valid until the next
+	// Read or Close on this Queue — callers must encrypt or copy each
+	// slice before the next call. Not safe for concurrent Reads; exactly
+	// one goroutine per Queue reads.
+	Read() ([][]byte, error)
+
+	// Write emits a single packet on the plaintext (outside→inside)
+	// delivery path. May run concurrently with WriteReject on the same
+	// Queue, but not with itself.
+	Write(p []byte) (int, error)
+
 	// WriteReject writes a single packet that originated from the inside
 	// path (reject replies or self-forward) using scratch state distinct
 	// from Write, so it can run concurrently with Write on the same Queue

overlay/noop.go

@@ -25,11 +25,7 @@ func (NoopTun) Name() string {
 	return "noop"
 }
 
-func (NoopTun) Read([]byte) (int, error) {
-	return 0, nil
-}
-
-func (NoopTun) ReadBatch() ([][]byte, error) {
+func (NoopTun) Read() ([][]byte, error) {
 	return nil, nil
 }
 

overlay/tun_android.go

@@ -18,7 +18,7 @@ import (
 )
 
 type tun struct {
-	io.ReadWriteCloser
+	rwc         io.ReadWriteCloser
 	fd          int
 	vpnNetworks []netip.Prefix
 	Routes      atomic.Pointer[[]Route]
@@ -29,11 +29,11 @@ type tun struct {
 	batchRet [1][]byte
 }
 
-func (t *tun) ReadBatch() ([][]byte, error) {
+func (t *tun) Read() ([][]byte, error) {
 	if t.readBuf == nil {
 		t.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := t.Read(t.readBuf)
+	n, err := t.rwc.Read(t.readBuf)
 	if err != nil {
 		return nil, err
 	}
@@ -41,8 +41,16 @@ func (t *tun) ReadBatch() ([][]byte, error) {
 	return t.batchRet[:], nil
 }
 
+func (t *tun) Write(p []byte) (int, error) {
+	return t.rwc.Write(p)
+}
+
 func (t *tun) WriteReject(p []byte) (int, error) {
-	return t.Write(p)
+	return t.rwc.Write(p)
+}
+
+func (t *tun) Close() error {
+	return t.rwc.Close()
 }
 
 func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
@@ -51,10 +59,10 @@ func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, vpnNetworks []net
 	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
 	t := &tun{
-		ReadWriteCloser: file,
-		fd:              deviceFd,
-		vpnNetworks:     vpnNetworks,
-		l:               l,
+		rwc:         file,
+		fd:          deviceFd,
+		vpnNetworks: vpnNetworks,
+		l:           l,
 	}
 
 	err := t.reload(c, true)

overlay/tun_darwin.go

@@ -23,7 +23,7 @@ import (
 )
 
 type tun struct {
-	io.ReadWriteCloser
+	rwc         io.ReadWriteCloser
 	Device      string
 	vpnNetworks []netip.Prefix
 	DefaultMTU  int
@@ -127,11 +127,11 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, _ bool) (
 	}
 
 	t := &tun{
-		ReadWriteCloser: os.NewFile(uintptr(fd), ""),
-		Device:          name,
-		vpnNetworks:     vpnNetworks,
-		DefaultMTU:      c.GetInt("tun.mtu", DefaultMTU),
-		l:               l,
+		rwc:         os.NewFile(uintptr(fd), ""),
+		Device:      name,
+		vpnNetworks: vpnNetworks,
+		DefaultMTU:  c.GetInt("tun.mtu", DefaultMTU),
+		l:           l,
 	}
 
 	err = t.reload(c, true)
@@ -161,8 +161,8 @@ func newTunFromFd(_ *config.C, _ *logrus.Logger, _ int, _ []netip.Prefix) (*tun,
 }
 
 func (t *tun) Close() error {
-	if t.ReadWriteCloser != nil {
-		return t.ReadWriteCloser.Close()
+	if t.rwc != nil {
+		return t.rwc.Close()
 	}
 	return nil
 }
@@ -506,20 +506,20 @@ func delRoute(prefix netip.Prefix, gateway netroute.Addr) error {
 	return nil
 }
 
-func (t *tun) Read(to []byte) (int, error) {
+func (t *tun) readOne(to []byte) (int, error) {
 	buf := make([]byte, len(to)+4)
 
-	n, err := t.ReadWriteCloser.Read(buf)
+	n, err := t.rwc.Read(buf)
 
 	copy(to, buf[4:])
 	return n - 4, err
 }
 
-func (t *tun) ReadBatch() ([][]byte, error) {
+func (t *tun) Read() ([][]byte, error) {
 	if t.readBuf == nil {
 		t.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := t.Read(t.readBuf)
+	n, err := t.readOne(t.readBuf)
 	if err != nil {
 		return nil, err
 	}
@@ -556,7 +556,7 @@ func (t *tun) Write(from []byte) (int, error) {
 
 	copy(buf[4:], from)
 
-	n, err := t.ReadWriteCloser.Write(buf)
+	n, err := t.rwc.Write(buf)
 	return n - 4, err
 }
 

overlay/tun_disabled.go

@@ -21,19 +21,21 @@ type disabledTun struct {
 	rx metrics.Counter
 	l  *logrus.Logger
 
-	readBuf  []byte
 	batchRet [1][]byte
 }
 
-func (t *disabledTun) ReadBatch() ([][]byte, error) {
-	if t.readBuf == nil {
-		t.readBuf = make([]byte, defaultBatchBufSize)
+func (t *disabledTun) Read() ([][]byte, error) {
+	r, ok := <-t.read
+	if !ok {
+		return nil, io.EOF
 	}
-	n, err := t.Read(t.readBuf)
-	if err != nil {
-		return nil, err
+
+	t.tx.Inc(1)
+	if t.l.Level >= logrus.DebugLevel {
+		t.l.WithField("raw", prettyPacket(r)).Debugf("Write payload")
 	}
-	t.batchRet[0] = t.readBuf[:n]
+
+	t.batchRet[0] = r
 	return t.batchRet[:], nil
 }
 
@@ -71,24 +73,6 @@ func (*disabledTun) Name() string {
 	return "disabled"
 }
 
-func (t *disabledTun) Read(b []byte) (int, error) {
-	r, ok := <-t.read
-	if !ok {
-		return 0, io.EOF
-	}
-
-	if len(r) > len(b) {
-		return 0, fmt.Errorf("packet larger than mtu: %d > %d bytes", len(r), len(b))
-	}
-
-	t.tx.Inc(1)
-	if t.l.Level >= logrus.DebugLevel {
-		t.l.WithField("raw", prettyPacket(r)).Debugf("Write payload")
-	}
-
-	return copy(b, r), nil
-}
-
 func (t *disabledTun) handleICMPEchoRequest(b []byte) bool {
 	out := make([]byte, len(b))
 	out = iputil.CreateICMPEchoResponse(b, out)

overlay/tun_freebsd.go

@@ -98,11 +98,11 @@ type tun struct {
 	batchRet [1][]byte
 }
 
-func (t *tun) ReadBatch() ([][]byte, error) {
+func (t *tun) Read() ([][]byte, error) {
 	if t.readBuf == nil {
 		t.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := t.Read(t.readBuf)
+	n, err := t.readOne(t.readBuf)
 	if err != nil {
 		return nil, err
 	}
@@ -114,7 +114,7 @@ func (t *tun) WriteReject(p []byte) (int, error) {
 	return t.Write(p)
 }
 
-func (t *tun) Read(to []byte) (int, error) {
+func (t *tun) readOne(to []byte) (int, error) {
 	// use readv() to read from the tunnel device, to eliminate the need for copying the buffer
 	if t.devFd < 0 {
 		return -1, syscall.EINVAL

overlay/tun_ios.go

@@ -21,7 +21,7 @@ import (
 )
 
 type tun struct {
-	io.ReadWriteCloser
+	rwc         io.ReadWriteCloser
 	vpnNetworks []netip.Prefix
 	Routes      atomic.Pointer[[]Route]
 	routeTree   atomic.Pointer[bart.Table[routing.Gateways]]
@@ -31,11 +31,11 @@ type tun struct {
 	batchRet [1][]byte
 }
 
-func (t *tun) ReadBatch() ([][]byte, error) {
+func (t *tun) Read() ([][]byte, error) {
 	if t.readBuf == nil {
 		t.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := t.Read(t.readBuf)
+	n, err := t.rwc.Read(t.readBuf)
 	if err != nil {
 		return nil, err
 	}
@@ -43,8 +43,16 @@ func (t *tun) ReadBatch() ([][]byte, error) {
 	return t.batchRet[:], nil
 }
 
+func (t *tun) Write(p []byte) (int, error) {
+	return t.rwc.Write(p)
+}
+
 func (t *tun) WriteReject(p []byte) (int, error) {
-	return t.Write(p)
+	return t.rwc.Write(p)
+}
+
+func (t *tun) Close() error {
+	return t.rwc.Close()
 }
 
 func newTun(_ *config.C, _ *logrus.Logger, _ []netip.Prefix, _ bool) (*tun, error) {
@@ -54,9 +62,9 @@ func newTun(_ *config.C, _ *logrus.Logger, _ []netip.Prefix, _ bool) (*tun, erro
 func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
 	file := os.NewFile(uintptr(deviceFd), "/dev/tun")
 	t := &tun{
-		vpnNetworks:     vpnNetworks,
-		ReadWriteCloser: &tunReadCloser{f: file},
-		l:               l,
+		vpnNetworks: vpnNetworks,
+		rwc:         &tunReadCloser{f: file},
+		l:           l,
 	}
 
 	err := t.reload(c, true)

overlay/tun_linux.go

@@ -41,13 +41,12 @@ type tunFile struct {
 	// kernel successfully accepted TUNSETOFFLOAD. Reads include a leading
 	// virtio_net_hdr and may carry a TSO superpacket we must segment;
 	// writes must prepend a zeroed virtio_net_hdr.
-	vnetHdr    bool
-	readBuf    []byte   // scratch for a single raw read (virtio hdr + superpacket)
-	segBuf     []byte   // backing store for segmented output
-	segOff     int      // cursor into segBuf for the current ReadBatch drain
-	pending    [][]byte // segments waiting to be drained by Read
-	pendingIdx int
-	writeIovs  [2]unix.Iovec // preallocated iovecs for Write (coalescer passthrough); iovs[0] is fixed to validVnetHdr
+	vnetHdr   bool
+	readBuf   []byte        // scratch for a single raw read (virtio hdr + superpacket)
+	segBuf    []byte        // backing store for segmented output
+	segOff    int           // cursor into segBuf for the current Read drain
+	pending   [][]byte      // segments returned from the most recent Read
+	writeIovs [2]unix.Iovec // preallocated iovecs for Write (coalescer passthrough); iovs[0] is fixed to validVnetHdr
 	// rejectIovs is a second preallocated iovec scratch used exclusively by
 	// WriteReject (reject + self-forward from the inside path). It mirrors
 	// writeIovs but lets listenIn goroutines emit reject packets without
@@ -217,16 +216,15 @@ func (r *tunFile) readRaw(buf []byte) (int, error) {
 	}
 }
 
-// ReadBatch reads one or more superpackets from the tun and returns the
+// Read reads one or more superpackets from the tun and returns the
 // resulting packets. The first read blocks via poll; once the fd is known
 // readable we drain additional packets non-blocking until the kernel queue
 // is empty (EAGAIN), we've collected tunDrainCap packets, or we're out of
 // segBuf headroom. This amortizes the poll wake over bursts of small
 // packets (e.g. TCP ACKs). Slices point into the tunFile's internal buffers
-// and are only valid until the next ReadBatch / Read / Close on this Queue.
-func (r *tunFile) ReadBatch() ([][]byte, error) {
+// and are only valid until the next Read or Close on this Queue.
+func (r *tunFile) Read() ([][]byte, error) {
 	r.pending = r.pending[:0]
-	r.pendingIdx = 0
 	r.segOff = 0
 
 	// Initial (blocking) read. Retry on decode errors so a single bad
@@ -291,25 +289,6 @@ func (r *tunFile) decodeRead(n int) error {
 	return nil
 }
 
-// Read drains segments produced by the last ReadBatch one at a time; when the
-// batch is exhausted it fetches a fresh one. Kept for io.Reader compatibility;
-// batch-aware callers should use ReadBatch directly.
-func (r *tunFile) Read(buf []byte) (int, error) {
-	for {
-		if r.pendingIdx < len(r.pending) {
-			seg := r.pending[r.pendingIdx]
-			r.pendingIdx++
-			if len(seg) > len(buf) {
-				return 0, io.ErrShortBuffer
-			}
-			return copy(buf, seg), nil
-		}
-		if _, err := r.ReadBatch(); err != nil {
-			return 0, err
-		}
-	}
-}
-
 func (r *tunFile) Write(buf []byte) (int, error) {
 	return r.writeWithScratch(buf, &r.writeIovs)
 }

overlay/tun_linux_offload.go

@@ -25,11 +25,11 @@ const tunSegBufSize = 131072
 
 // tunSegBufCap is the total size we allocate for the per-reader segment
 // buffer. It is sized as one worst-case TSO superpacket (tunSegBufSize) plus
-// the same again as drain headroom so a ReadBatch wake can accumulate
+// the same again as drain headroom so a Read wake can accumulate
 // additional packets after an initial big read without overflowing.
 const tunSegBufCap = tunSegBufSize * 2
 
-// tunDrainCap caps how many packets a single ReadBatch will accumulate via
+// tunDrainCap caps how many packets a single Read will accumulate via
 // the post-wake drain loop. Sized to soak up a burst of small ACKs while
 // bounding how much work a single caller holds before handing off.
 const tunDrainCap = 64

overlay/tun_netbsd.go

@@ -70,11 +70,11 @@ type tun struct {
 	batchRet [1][]byte
 }
 
-func (t *tun) ReadBatch() ([][]byte, error) {
+func (t *tun) Read() ([][]byte, error) {
 	if t.readBuf == nil {
 		t.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := t.Read(t.readBuf)
+	n, err := t.readOne(t.readBuf)
 	if err != nil {
 		return nil, err
 	}
@@ -159,7 +159,7 @@ func (t *tun) Close() error {
 	return nil
 }
 
-func (t *tun) Read(to []byte) (int, error) {
+func (t *tun) readOne(to []byte) (int, error) {
 	rc, err := t.f.SyscallConn()
 	if err != nil {
 		return 0, fmt.Errorf("failed to get syscall conn for tun: %w", err)

overlay/tun_openbsd.go

@@ -63,11 +63,11 @@ type tun struct {
 	batchRet [1][]byte
 }
 
-func (t *tun) ReadBatch() ([][]byte, error) {
+func (t *tun) Read() ([][]byte, error) {
 	if t.readBuf == nil {
 		t.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := t.Read(t.readBuf)
+	n, err := t.readOne(t.readBuf)
 	if err != nil {
 		return nil, err
 	}
@@ -142,7 +142,7 @@ func (t *tun) Close() error {
 	return nil
 }
 
-func (t *tun) Read(to []byte) (int, error) {
+func (t *tun) readOne(to []byte) (int, error) {
 	buf := make([]byte, len(to)+4)
 
 	n, err := t.f.Read(buf)

overlay/tun_tester.go

@@ -27,19 +27,15 @@ type TestTun struct {
 	rxPackets chan []byte // Packets to receive into nebula
 	TxPackets chan []byte // Packets transmitted outside by nebula
 
-	readBuf  []byte
 	batchRet [1][]byte
 }
 
-func (t *TestTun) ReadBatch() ([][]byte, error) {
-	if t.readBuf == nil {
-		t.readBuf = make([]byte, defaultBatchBufSize)
-	}
-	n, err := t.Read(t.readBuf)
-	if err != nil {
-		return nil, err
+func (t *TestTun) Read() ([][]byte, error) {
+	p, ok := <-t.rxPackets
+	if !ok {
+		return nil, os.ErrClosed
 	}
-	t.batchRet[0] = t.readBuf[:n]
+	t.batchRet[0] = p
 	return t.batchRet[:], nil
 }
 
@@ -142,15 +138,6 @@ func (t *TestTun) Close() error {
 	return nil
 }
 
-func (t *TestTun) Read(b []byte) (int, error) {
-	p, ok := <-t.rxPackets
-	if !ok {
-		return 0, os.ErrClosed
-	}
-	copy(b, p)
-	return len(p), nil
-}
-
 func (t *TestTun) SupportsMultiqueue() bool {
 	return false
 }

overlay/tun_windows.go

@@ -40,11 +40,11 @@ type winTun struct {
 	batchRet [1][]byte
 }
 
-func (t *winTun) ReadBatch() ([][]byte, error) {
+func (t *winTun) Read() ([][]byte, error) {
 	if t.readBuf == nil {
 		t.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := t.Read(t.readBuf)
+	n, err := t.tun.Read(t.readBuf, 0)
 	if err != nil {
 		return nil, err
 	}
@@ -247,10 +247,6 @@ func (t *winTun) Name() string {
 	return t.Device
 }
 
-func (t *winTun) Read(b []byte) (int, error) {
-	return t.tun.Read(b, 0)
-}
-
 func (t *winTun) Write(b []byte) (int, error) {
 	return t.tun.Write(b, 0)
 }

overlay/user.go

@@ -39,11 +39,11 @@ type UserDevice struct {
 	batchRet [1][]byte
 }
 
-func (d *UserDevice) ReadBatch() ([][]byte, error) {
+func (d *UserDevice) Read() ([][]byte, error) {
 	if d.readBuf == nil {
 		d.readBuf = make([]byte, defaultBatchBufSize)
 	}
-	n, err := d.Read(d.readBuf)
+	n, err := d.outboundReader.Read(d.readBuf)
 	if err != nil {
 		return nil, err
 	}
@@ -73,9 +73,6 @@ func (d *UserDevice) Pipe() (*io.PipeReader, *io.PipeWriter) {
 	return d.inboundReader, d.outboundWriter
 }
 
-func (d *UserDevice) Read(p []byte) (n int, err error) {
-	return d.outboundReader.Read(p)
-}
 func (d *UserDevice) Write(p []byte) (n int, err error) {
 	return d.inboundWriter.Write(p)
 }