change Queue.Read signature

overlay/tio/tio.go

@@ -2,6 +2,8 @@ package tio
 
 import (
 	"io"
+
+	"github.com/slackhq/nebula/wire"
 )
 
 // QueueSet holds one or many Queue objects and helps close them in an orderly way.
@@ -13,17 +15,10 @@ type QueueSet interface {
 	Add(fd int) error
 }
 
-// Capabilities advertises which kernel offload features a Queue
-// successfully negotiated. Callers consult this to decide which coalescers
-// to wire onto the write path — a Queue without TSO can't usefully accept a
-// TCPCoalescer, and a Queue without USO can't accept a UDPCoalescer.
+// Capabilities advertises which kernel offload features a Queue successfully negotiated.
+// Callers consult this to decide which coalescers to wire onto the write path.
 type Capabilities struct {
-	// TSO means the FD was opened with IFF_VNET_HDR and the kernel agreed
-	// to TUN_F_TSO4|TSO6 — i.e. WriteGSO with GSOProtoTCP is safe.
-	TSO bool
-	// USO means the kernel additionally agreed to TUN_F_USO4|USO6, so
-	// WriteGSO with GSOProtoUDP is safe. Linux ≥ 6.2.
-	USO bool
+	//none yet!
 }
 
 // Queue is a readable/writable Poll queue. One Queue is driven by a single
@@ -31,62 +26,16 @@ type Capabilities struct {
 type Queue interface {
 	io.Closer
 
-	// Read returns one or more packets. The returned Packet.Bytes 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.
-	Read() ([]Packet, error)
+	// Read will read at least 1 packet from the tun (up to len(p))
+	// mem will be used to provide the backing for each of p[n].Bytes
+	// Returns the number of packets actually read, or error
+	Read(p []wire.TunPacket, mem []byte) (int, error)
 
 	// Write emits a single packet on the plaintext (outside→inside)
-	// delivery path. Not safe for concurrent Writes.
+	// delivery path.
 	Write(p []byte) (int, error)
 
 	// Capabilities returns the Queue's negotiated offload capabilities,
 	// or the zero value when q does not advertise any.
 	Capabilities() Capabilities
 }
-
-// Packet is the unit Queue.Read returns. Bytes points into the queue's
-// internal buffer and is only valid until the next Read or Close on the
-// queue that produced it. GSO is the zero value for an already-segmented
-// IP datagram; when non-zero it describes a kernel-supplied TSO/USO
-// superpacket the caller must segment before consuming.
-type Packet struct {
-	Bytes []byte
-	GSO   GSOInfo
-}
-
-// GSOInfo describes a kernel-supplied superpacket sitting in Packet.Bytes.
-// The zero value means "not a superpacket" — Bytes is one regular IP
-// datagram and no segmentation is required.
-type GSOInfo struct {
-	// Size is the GSO segment size: max payload bytes per segment
-	// (== TCP MSS for TSO, == UDP payload chunk for USO). Zero means
-	// not a superpacket.
-	Size uint16
-	// HdrLen is the total L3+L4 header length within Bytes (already
-	// corrected via correctHdrLen, so safe to slice on).
-	HdrLen uint16
-	// CsumStart is the L4 header offset inside Bytes (== L3 header
-	// length).
-	CsumStart uint16
-	// Proto picks the L4 protocol (TCP or UDP) so the segmenter knows
-	// which checksum/header layout to apply.
-	Proto GSOProto
-}
-
-// IsSuperpacket reports whether g describes a multi-segment GSO/USO
-// superpacket that needs segmentation before its bytes can be encrypted
-// and sent on the wire.
-func (g GSOInfo) IsSuperpacket() bool { return g.Size > 0 }
-
-// GSOProto selects the L4 protocol for a GSO superpacket. Determines which
-// VIRTIO_NET_HDR_GSO_* type the writer stamps and which checksum offset
-// inside the transport header virtio NEEDS_CSUM expects.
-type GSOProto uint8
-
-const (
-	GSOProtoNone GSOProto = iota
-	GSOProtoTCP
-	GSOProtoUDP
-)

overlay/tio/tio_poll_linux.go

@@ -6,6 +6,7 @@ import (
 	"sync"
 	"sync/atomic"
 
+	"github.com/slackhq/nebula/wire"
 	"golang.org/x/sys/unix"
 )
 
@@ -16,9 +17,6 @@ type Poll struct {
 	writePoll [2]unix.PollFd
 	writeLock sync.Mutex
 	closed    atomic.Bool
-
-	readBuf  []byte
-	batchRet [1]Packet
 }
 
 func newPoll(fd int, shutdownFd int) (*Poll, error) {
@@ -28,8 +26,7 @@ func newPoll(fd int, shutdownFd int) (*Poll, error) {
 	}
 
 	out := &Poll{
-		fd:      fd,
-		readBuf: make([]byte, 65535),
+		fd: fd,
 		readPoll: [2]unix.PollFd{
 			{Fd: int32(fd), Events: unix.POLLIN},
 			{Fd: int32(shutdownFd), Events: unix.POLLIN},
@@ -97,13 +94,17 @@ func (t *Poll) blockOnWrite() error {
 	return nil
 }
 
-func (t *Poll) Read() ([]Packet, error) {
-	n, err := t.readOne(t.readBuf)
-	if err != nil {
-		return nil, err
+func (t *Poll) Read(p []wire.TunPacket, mem []byte) (int, error) {
+	if len(p) == 0 || len(mem) == 0 {
+		return 0, nil //todo should this be an err?
 	}
-	t.batchRet[0] = Packet{Bytes: t.readBuf[:n]}
-	return t.batchRet[:], nil
+	p[0].Meta = struct{}{}
+	n, err := t.readOne(mem)
+	if err != nil {
+		return 0, err
+	}
+	p[0].Bytes = mem[:n]
+	return 1, nil
 }
 
 func (t *Poll) readOne(to []byte) (int, error) {
@@ -163,5 +164,5 @@ func (t *Poll) Close() error {
 }
 
 func (t *Poll) Capabilities() Capabilities {
-	return Capabilities{TSO: false, USO: false}
+	return Capabilities{}
 }