hmm

This reverts commit fa098c551a.

bits.go

@@ -5,6 +5,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+// TODO: Pretty sure this is just all sorts of racy now, we need it to be atomic
 type Bits struct {
 	length             uint64
 	current            uint64
@@ -43,7 +44,7 @@ func (b *Bits) Check(l logrus.FieldLogger, i uint64) bool {
 	}
 
 	// Not within the window
-	l.Debugf("rejected a packet (top) %d %d\n", b.current, i)
+	l.Error("rejected a packet (top) %d %d\n", b.current, i)
 	return false
 }
 

cmd/nebula-service/main.go

@@ -65,8 +65,16 @@ func main() {
 	}
 
 	if !*configTest {
-		ctrl.Start()
+		wait, err := ctrl.Start()
-		ctrl.ShutdownBlock()
+		if err != nil {
+			util.LogWithContextIfNeeded("Error while running", err, l)
+			os.Exit(1)
+		}
+
+		go ctrl.ShutdownBlock()
+		wait()
+
+		l.Info("Goodbye")
 	}
 
 	os.Exit(0)

cmd/nebula/main.go

@@ -3,6 +3,9 @@ package main
 import (
 	"flag"
 	"fmt"
+	"log"
+	"net/http"
+	_ "net/http/pprof"
 	"os"
 
 	"github.com/sirupsen/logrus"
@@ -58,10 +61,22 @@ func main() {
 		os.Exit(1)
 	}
 
+	go func() {
+		log.Println(http.ListenAndServe("0.0.0.0:6060", nil))
+	}()
+
 	if !*configTest {
-		ctrl.Start()
+		wait, err := ctrl.Start()
+		if err != nil {
+			util.LogWithContextIfNeeded("Error while running", err, l)
+			os.Exit(1)
+		}
+
+		go ctrl.ShutdownBlock()
 		notifyReady(l)
-		ctrl.ShutdownBlock()
+		wait()
+
+		l.Info("Goodbye")
 	}
 
 	os.Exit(0)

connection_state.go

@@ -13,7 +13,9 @@ import (
 	"github.com/slackhq/nebula/noiseutil"
 )
 
-const ReplayWindow = 1024
+// TODO: In a 5Gbps test, 1024 is not sufficient. With a 1400 MTU this is about 1.4Gbps of window, assuming full packets.
+// 4092 should be sufficient for 5Gbps
+const ReplayWindow = 8192
 
 type ConnectionState struct {
 	eKey           *NebulaCipherState

control.go

@@ -2,9 +2,11 @@ package nebula
 
 import (
 	"context"
+	"errors"
 	"net/netip"
 	"os"
 	"os/signal"
+	"sync"
 	"syscall"
 
 	"github.com/sirupsen/logrus"
@@ -13,6 +15,16 @@ import (
 	"github.com/slackhq/nebula/overlay"
 )
 
+type RunState int
+
+const (
+	Stopped  RunState = 0 // The control has yet to be started
+	Started  RunState = 1 // The control has been started
+	Stopping RunState = 2 // The control is stopping
+)
+
+var ErrAlreadyStarted = errors.New("nebula is already started")
+
 // Every interaction here needs to take extra care to copy memory and not return or use arguments "as is" when touching
 // core. This means copying IP objects, slices, de-referencing pointers and taking the actual value, etc
 
@@ -26,6 +38,9 @@ type controlHostLister interface {
 }
 
 type Control struct {
+	stateLock sync.Mutex
+	state     RunState
+
 	f                      *Interface
 	l                      *logrus.Logger
 	ctx                    context.Context
@@ -49,10 +64,21 @@ type ControlHostInfo struct {
 	CurrentRelaysThroughMe []netip.Addr     `json:"currentRelaysThroughMe"`
 }
 
-// Start actually runs nebula, this is a nonblocking call. To block use Control.ShutdownBlock()
+// Start actually runs nebula, this is a nonblocking call.
-func (c *Control) Start() {
+// The returned function can be used to wait for nebula to fully stop.
+func (c *Control) Start() (func(), error) {
+	c.stateLock.Lock()
+	if c.state != Stopped {
+		c.stateLock.Unlock()
+		return nil, ErrAlreadyStarted
+	}
+
 	// Activate the interface
-	c.f.activate()
+	err := c.f.activate()
+	if err != nil {
+		c.stateLock.Unlock()
+		return nil, err
+	}
 
 	// Call all the delayed funcs that waited patiently for the interface to be created.
 	if c.sshStart != nil {
@@ -72,15 +98,33 @@ func (c *Control) Start() {
 	}
 
 	// Start reading packets.
-	c.f.run()
+	c.state = Started
+	c.stateLock.Unlock()
+	return c.f.run(c.ctx)
+}
+
+func (c *Control) State() RunState {
+	c.stateLock.Lock()
+	defer c.stateLock.Unlock()
+	return c.state
 }
 
 func (c *Control) Context() context.Context {
 	return c.ctx
 }
 
-// Stop signals nebula to shutdown and close all tunnels, returns after the shutdown is complete
+// Stop is a non-blocking call that signals nebula to close all tunnels and shut down
 func (c *Control) Stop() {
+	c.stateLock.Lock()
+	if c.state != Started {
+		c.stateLock.Unlock()
+		// We are stopping or stopped already
+		return
+	}
+
+	c.state = Stopping
+	c.stateLock.Unlock()
+
 	// Stop the handshakeManager (and other services), to prevent new tunnels from
 	// being created while we're shutting them all down.
 	c.cancel()
@@ -89,7 +133,7 @@ func (c *Control) Stop() {
 	if err := c.f.Close(); err != nil {
 		c.l.WithError(err).Error("Close interface failed")
 	}
-	c.l.Info("Goodbye")
+	c.state = Stopped
 }
 
 // ShutdownBlock will listen for and block on term and interrupt signals, calling Control.Stop() once signalled

interface.go

@@ -6,8 +6,8 @@ import (
 	"fmt"
 	"io"
 	"net/netip"
-	"os"
 	"runtime"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -18,6 +18,7 @@ import (
 	"github.com/slackhq/nebula/firewall"
 	"github.com/slackhq/nebula/header"
 	"github.com/slackhq/nebula/overlay"
+	"github.com/slackhq/nebula/packet"
 	"github.com/slackhq/nebula/udp"
 )
 
@@ -87,12 +88,17 @@ type Interface struct {
 
 	writers []udp.Conn
 	readers []io.ReadWriteCloser
+	wg      sync.WaitGroup
 
 	metricHandshakes    metrics.Histogram
 	messageMetrics      *MessageMetrics
 	cachedPacketMetrics *cachedPacketMetrics
 
 	l *logrus.Logger
+
+	pktPool  *packet.Pool
+	inbound  chan *packet.Packet
+	outbound chan *packet.Packet
 }
 
 type EncWriter interface {
@@ -194,9 +200,15 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 			dropped: metrics.GetOrRegisterCounter("hostinfo.cached_packets.dropped", nil),
 		},
 
+		//TODO: configurable size
+		inbound:  make(chan *packet.Packet, 2048),
+		outbound: make(chan *packet.Packet, 2048),
+
 		l: c.l,
 	}
 
+	ifce.pktPool = packet.NewPool()
+
 	ifce.tryPromoteEvery.Store(c.tryPromoteEvery)
 	ifce.reQueryEvery.Store(c.reQueryEvery)
 	ifce.reQueryWait.Store(int64(c.reQueryWait))
@@ -209,7 +221,7 @@ func NewInterface(ctx context.Context, c *InterfaceConfig) (*Interface, error) {
 // activate creates the interface on the host. After the interface is created, any
 // other services that want to bind listeners to its IP may do so successfully. However,
 // the interface isn't going to process anything until run() is called.
-func (f *Interface) activate() {
+func (f *Interface) activate() error {
 	// actually turn on tun dev
 
 	addr, err := f.outside.LocalAddr()
@@ -230,33 +242,46 @@ func (f *Interface) activate() {
 		if i > 0 {
 			reader, err = f.inside.NewMultiQueueReader()
 			if err != nil {
-				f.l.Fatal(err)
+				return err
 			}
 		}
 		f.readers[i] = reader
 	}
 
-	if err := f.inside.Activate(); err != nil {
+	if err = f.inside.Activate(); err != nil {
 		f.inside.Close()
-		f.l.Fatal(err)
+		return err
 	}
+
+	return nil
 }
 
-func (f *Interface) run() {
+func (f *Interface) run(c context.Context) (func(), error) {
-	// Launch n queues to read packets from udp
 	for i := 0; i < f.routines; i++ {
+		// read packets from udp and queue to f.inbound
+		f.wg.Add(1)
 		go f.listenOut(i)
+
+		// Launch n queues to read packets from inside tun dev and queue to f.outbound
+		//todo this never stops f.wg.Add(1)
+		go f.listenIn(f.readers[i], i)
+
+		// Launch n workers to process traffic from f.inbound and smash it onto the inside of the tun
+		f.wg.Add(1)
+		go f.workerIn(i, c)
+		f.wg.Add(1)
+		go f.workerIn(i, c)
+
+		// read from f.outbound and write to UDP (outside the tun)
+		f.wg.Add(1)
+		go f.workerOut(i, c)
 	}
 
-	// Launch n queues to read packets from tun dev
+	return f.wg.Wait, nil
-	for i := 0; i < f.routines; i++ {
-		go f.listenIn(f.readers[i], i)
-	}
 }
 
 func (f *Interface) listenOut(i int) {
 	runtime.LockOSThread()
-
 	var li udp.Conn
 	if i > 0 {
 		li = f.writers[i]
@@ -264,41 +289,79 @@ func (f *Interface) listenOut(i int) {
 		li = f.outside
 	}
 
-	ctCache := firewall.NewConntrackCacheTicker(f.conntrackCacheTimeout)
+	err := li.ListenOut(f.pktPool.Get, f.inbound)
-	lhh := f.lightHouse.NewRequestHandler()
+	if err != nil && !f.closed.Load() {
-	plaintext := make([]byte, udp.MTU)
+		f.l.WithError(err).Error("Error while reading packet inbound packet, closing")
-	h := &header.H{}
+		//TODO: Trigger Control to close
-	fwPacket := &firewall.Packet{}
+	}
-	nb := make([]byte, 12, 12)
 
-	li.ListenOut(func(fromUdpAddr netip.AddrPort, payload []byte) {
+	f.l.Debugf("underlay reader %v is done", i)
-		f.readOutsidePackets(fromUdpAddr, nil, plaintext[:0], payload, h, fwPacket, lhh, nb, i, ctCache.Get(f.l))
+	f.wg.Done()
-	})
 }
 
 func (f *Interface) listenIn(reader io.ReadWriteCloser, i int) {
 	runtime.LockOSThread()
 
-	packet := make([]byte, mtu)
+	for {
-	out := make([]byte, mtu)
+		p := f.pktPool.Get()
-	fwPacket := &firewall.Packet{}
+		n, err := reader.Read(p.Payload)
-	nb := make([]byte, 12, 12)
+		if err != nil {
+			if !f.closed.Load() {
+				f.l.WithError(err).Error("Error while reading outbound packet, closing")
+				//TODO: Trigger Control to close
+			}
+			break
+		}
 
+		p.Payload = (p.Payload)[:n]
+		//TODO: nonblocking channel write
+		f.outbound <- p
+		//select {
+		//case f.outbound <- p:
+		//default:
+		//	f.l.Error("Dropped packet from outbound channel")
+		//}
+	}
+
+	f.l.Debugf("overlay reader %v is done", i)
+	f.wg.Done()
+}
+
+func (f *Interface) workerIn(i int, ctx context.Context) {
+	lhh := f.lightHouse.NewRequestHandler()
 	conntrackCache := firewall.NewConntrackCacheTicker(f.conntrackCacheTimeout)
+	fwPacket2 := &firewall.Packet{}
+	nb2 := make([]byte, 12, 12)
+	result2 := make([]byte, mtu)
+	h := &header.H{}
 
 	for {
-		n, err := reader.Read(packet)
+		select {
-		if err != nil {
+		case p := <-f.inbound:
-			if errors.Is(err, os.ErrClosed) && f.closed.Load() {
+			f.readOutsidePackets(p.Addr, nil, result2[:0], p.Payload, h, fwPacket2, lhh, nb2, i, conntrackCache.Get(f.l))
+			f.pktPool.Put(p)
+		case <-ctx.Done():
+			f.wg.Done()
 			return
 		}
-
-			f.l.WithError(err).Error("Error while reading outbound packet")
-			// This only seems to happen when something fatal happens to the fd, so exit.
-			os.Exit(2)
 	}
+}
 
-		f.consumeInsidePacket(packet[:n], fwPacket, nb, out, i, conntrackCache.Get(f.l))
+func (f *Interface) workerOut(i int, ctx context.Context) {
+	conntrackCache := firewall.NewConntrackCacheTicker(f.conntrackCacheTimeout)
+	fwPacket1 := &firewall.Packet{}
+	nb1 := make([]byte, 12, 12)
+	result1 := make([]byte, mtu)
+
+	for {
+		select {
+		case data := <-f.outbound:
+			f.consumeInsidePacket(data.Payload, fwPacket1, nb1, result1, i, conntrackCache.Get(f.l))
+			f.pktPool.Put(data)
+		case <-ctx.Done():
+			f.wg.Done()
+			return
+		}
 	}
 }
 
@@ -451,6 +514,7 @@ func (f *Interface) GetCertState() *CertState {
 func (f *Interface) Close() error {
 	f.closed.Store(true)
 
+	// Release the udp readers
 	for _, u := range f.writers {
 		err := u.Close()
 		if err != nil {
@@ -458,6 +522,13 @@ func (f *Interface) Close() error {
 		}
 	}
 
-	// Release the tun device
+	// Release the tun readers
-	return f.inside.Close()
+	for _, u := range f.readers {
+		err := u.Close()
+		if err != nil {
+			f.l.WithError(err).Error("Error while closing tun device")
+		}
+	}
+
+	return nil
 }

main.go

@@ -284,14 +284,14 @@ func Main(c *config.C, configTest bool, buildVersion string, logger *logrus.Logg
 	}
 
 	return &Control{
-		ifce,
+		f:                      ifce,
-		l,
+		l:                      l,
-		ctx,
+		ctx:                    ctx,
-		cancel,
+		cancel:                 cancel,
-		sshStart,
+		sshStart:               sshStart,
-		statsStart,
+		statsStart:             statsStart,
-		dnsStart,
+		dnsStart:               dnsStart,
-		lightHouse.StartUpdateWorker,
+		lighthouseStart:        lightHouse.StartUpdateWorker,
-		connManager.Start,
+		connectionManagerStart: connManager.Start,
 	}, nil
 }

outside.go

@@ -29,7 +29,7 @@ func (f *Interface) readOutsidePackets(ip netip.AddrPort, via *ViaSender, out []
 		return
 	}
 
-	//l.Error("in packet ", header, packet[HeaderLen:])
+	//f.l.Error("in packet ", h)
 	if ip.IsValid() {
 		if f.myVpnNetworksTable.Contains(ip.Addr()) {
 			if f.l.Level >= logrus.DebugLevel {
@@ -245,6 +245,7 @@ func (f *Interface) handleHostRoaming(hostinfo *HostInfo, udpAddr netip.AddrPort
 			return
 		}
 
+		//TODO: Seems we have a bunch of stuff racing here, since we don't have a lock on hostinfo anymore we announce roaming in bursts
 		hostinfo.logger(f.l).WithField("udpAddr", hostinfo.remote).WithField("newAddr", udpAddr).
 			Info("Host roamed to new udp ip/port.")
 		hostinfo.lastRoam = time.Now()
@@ -470,7 +471,7 @@ func (f *Interface) decryptToTun(hostinfo *HostInfo, messageCounter uint64, out
 
 	out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, packet[:header.Len], packet[header.Len:], messageCounter, nb)
 	if err != nil {
-		hostinfo.logger(f.l).WithError(err).Error("Failed to decrypt packet")
+		hostinfo.logger(f.l).WithError(err).WithField("fwPacket", fwPacket).Error("Failed to decrypt packet")
 		return false
 	}
 

packet/packet.go

@@ -0,0 +1,36 @@
+package packet
+
+import (
+	"net/netip"
+	"sync"
+)
+
+const Size = 9001
+
+type Packet struct {
+	Payload []byte
+	Addr    netip.AddrPort
+}
+
+func New() *Packet {
+	return &Packet{Payload: make([]byte, Size)}
+}
+
+type Pool struct {
+	pool sync.Pool
+}
+
+func NewPool() *Pool {
+	return &Pool{
+		pool: sync.Pool{New: func() any { return New() }},
+	}
+}
+
+func (p *Pool) Get() *Packet {
+	return p.pool.Get().(*Packet)
+}
+
+func (p *Pool) Put(x *Packet) {
+	x.Payload = x.Payload[:Size]
+	p.pool.Put(x)
+}

service/service.go

@@ -9,10 +9,13 @@ import (
 	"math"
 	"net"
 	"net/netip"
+	"os"
 	"strings"
 	"sync"
 
+	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula"
+	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/overlay"
 	"golang.org/x/sync/errgroup"
 	"gvisor.dev/gvisor/pkg/buffer"
@@ -43,8 +46,19 @@ type Service struct {
 	}
 }
 
-func New(control *nebula.Control) (*Service, error) {
+func New(config *config.C) (*Service, error) {
-	control.Start()
+	logger := logrus.New()
+	logger.Out = os.Stdout
+
+	control, err := nebula.Main(config, false, "custom-app", logger, overlay.NewUserDeviceFromConfig)
+	if err != nil {
+		return nil, err
+	}
+
+	wait, err := control.Start()
+	if err != nil {
+		return nil, err
+	}
 
 	ctx := control.Context()
 	eg, ctx := errgroup.WithContext(ctx)
@@ -141,6 +155,12 @@ func New(control *nebula.Control) (*Service, error) {
 		}
 	})
 
+	// Add the nebula wait function to the group
+	eg.Go(func() error {
+		wait()
+		return nil
+	})
+
 	return &s, nil
 }
 

udp/conn.go

@@ -4,19 +4,19 @@ import (
 	"net/netip"
 
 	"github.com/slackhq/nebula/config"
+	"github.com/slackhq/nebula/packet"
 )
 
 const MTU = 9001
 
-type EncReader func(
+type EncReader func(*packet.Packet)
-	addr netip.AddrPort,
+
-	payload []byte,
+type PacketBufferGetter func() *packet.Packet
-)
 
 type Conn interface {
 	Rebind() error
 	LocalAddr() (netip.AddrPort, error)
-	ListenOut(r EncReader)
+	ListenOut(pg PacketBufferGetter, pc chan *packet.Packet) error
 	WriteTo(b []byte, addr netip.AddrPort) error
 	ReloadConfig(c *config.C)
 	Close() error

udp/udp_generic.go

@@ -71,15 +71,14 @@ type rawMessage struct {
 	Len uint32
 }
 
-func (u *GenericConn) ListenOut(r EncReader) {
+func (u *GenericConn) ListenOut(r EncReader) error {
 	buffer := make([]byte, MTU)
 
 	for {
 		// Just read one packet at a time
 		n, rua, err := u.ReadFromUDPAddrPort(buffer)
 		if err != nil {
-			u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
+			return err
-			return
 		}
 
 		r(netip.AddrPortFrom(rua.Addr().Unmap(), rua.Port()), buffer[:n])

udp/udp_linux.go

@@ -9,14 +9,18 @@ import (
 	"net"
 	"net/netip"
 	"syscall"
+	"time"
 	"unsafe"
 
 	"github.com/rcrowley/go-metrics"
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/config"
+	"github.com/slackhq/nebula/packet"
 	"golang.org/x/sys/unix"
 )
 
+var readTimeout = unix.NsecToTimeval(int64(time.Millisecond * 500))
+
 type StdConn struct {
 	sysFd int
 	isV4  bool
@@ -24,14 +28,6 @@ type StdConn struct {
 	batch int
 }
 
-func maybeIPV4(ip net.IP) (net.IP, bool) {
-	ip4 := ip.To4()
-	if ip4 != nil {
-		return ip4, true
-	}
-	return ip, false
-}
-
 func NewListener(l *logrus.Logger, ip netip.Addr, port int, multi bool, batch int) (Conn, error) {
 	af := unix.AF_INET6
 	if ip.Is4() {
@@ -55,6 +51,11 @@ func NewListener(l *logrus.Logger, ip netip.Addr, port int, multi bool, batch in
 		}
 	}
 
+	// Set a read timeout
+	if err = unix.SetsockoptTimeval(fd, unix.SOL_SOCKET, unix.SO_RCVTIMEO, &readTimeout); err != nil {
+		return nil, fmt.Errorf("unable to set SO_RCVTIMEO: %s", err)
+	}
+
 	var sa unix.Sockaddr
 	if ip.Is4() {
 		sa4 := &unix.SockaddrInet4{Port: port}
@@ -118,10 +119,10 @@ func (u *StdConn) LocalAddr() (netip.AddrPort, error) {
 	}
 }
 
-func (u *StdConn) ListenOut(r EncReader) {
+func (u *StdConn) ListenOut(pg PacketBufferGetter, pc chan *packet.Packet) error {
 	var ip netip.Addr
 
-	msgs, buffers, names := u.PrepareRawMessages(u.batch)
+	msgs, packets, names := u.PrepareRawMessages(u.batch, pg)
 	read := u.ReadMulti
 	if u.batch == 1 {
 		read = u.ReadSingle
@@ -130,18 +131,25 @@ func (u *StdConn) ListenOut(r EncReader) {
 	for {
 		n, err := read(msgs)
 		if err != nil {
-			u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
+			return err
-			return
 		}
 
 		for i := 0; i < n; i++ {
+			out := packets[i]
+			out.Payload = out.Payload[:msgs[i].Len]
+
 			// Its ok to skip the ok check here, the slicing is the only error that can occur and it will panic
 			if u.isV4 {
 				ip, _ = netip.AddrFromSlice(names[i][4:8])
 			} else {
 				ip, _ = netip.AddrFromSlice(names[i][8:24])
 			}
-			r(netip.AddrPortFrom(ip.Unmap(), binary.BigEndian.Uint16(names[i][2:4])), buffers[i][:msgs[i].Len])
+			out.Addr = netip.AddrPortFrom(ip.Unmap(), binary.BigEndian.Uint16(names[i][2:4]))
+			pc <- out
+
+			//rotate this packet out so we don't overwrite it
+			packets[i] = pg()
+			msgs[i].Hdr.Iov.Base = &packets[i].Payload[0]
 		}
 	}
 }
@@ -159,6 +167,9 @@ func (u *StdConn) ReadSingle(msgs []rawMessage) (int, error) {
 		)
 
 		if err != 0 {
+			if err == unix.EAGAIN || err == unix.EINTR {
+				continue
+			}
 			return 0, &net.OpError{Op: "recvmsg", Err: err}
 		}
 
@@ -180,6 +191,9 @@ func (u *StdConn) ReadMulti(msgs []rawMessage) (int, error) {
 		)
 
 		if err != 0 {
+			if err == unix.EAGAIN || err == unix.EINTR {
+				continue
+			}
 			return 0, &net.OpError{Op: "recvmmsg", Err: err}
 		}
 
@@ -221,7 +235,7 @@ func (u *StdConn) writeTo6(b []byte, ip netip.AddrPort) error {
 
 func (u *StdConn) writeTo4(b []byte, ip netip.AddrPort) error {
 	if !ip.Addr().Is4() {
-		return ErrInvalidIPv6RemoteForSocket
+		return fmt.Errorf("Listener is IPv4, but writing to IPv6 remote")
 	}
 
 	var rsa unix.RawSockaddrInet4

udp/udp_linux_64.go

@@ -7,6 +7,7 @@
 package udp
 
 import (
+	"github.com/slackhq/nebula/packet"
 	"golang.org/x/sys/unix"
 )
 
@@ -33,17 +34,20 @@ type rawMessage struct {
 	Pad0 [4]byte
 }
 
-func (u *StdConn) PrepareRawMessages(n int) ([]rawMessage, [][]byte, [][]byte) {
+func (u *StdConn) PrepareRawMessages(n int, pg PacketBufferGetter) ([]rawMessage, []*packet.Packet, [][]byte) {
 	msgs := make([]rawMessage, n)
-	buffers := make([][]byte, n)
 	names := make([][]byte, n)
 
+	packets := make([]*packet.Packet, n)
+	for i := range packets {
+		packets[i] = pg()
+	}
+
 	for i := range msgs {
-		buffers[i] = make([]byte, MTU)
 		names[i] = make([]byte, unix.SizeofSockaddrInet6)
 
 		vs := []iovec{
-			{Base: &buffers[i][0], Len: uint64(len(buffers[i]))},
+			{Base: &packets[i].Payload[0], Len: uint64(packet.Size)},
 		}
 
 		msgs[i].Hdr.Iov = &vs[0]
@@ -53,5 +57,5 @@ func (u *StdConn) PrepareRawMessages(n int) ([]rawMessage, [][]byte, [][]byte) {
 		msgs[i].Hdr.Namelen = uint32(len(names[i]))
 	}
 
-	return msgs, buffers, names
+	return msgs, packets, names
 }

udp/udp_rio_windows.go

@@ -134,7 +134,7 @@ func (u *RIOConn) bind(sa windows.Sockaddr) error {
 	return nil
 }
 
-func (u *RIOConn) ListenOut(r EncReader) {
+func (u *RIOConn) ListenOut(r EncReader) error {
 	buffer := make([]byte, MTU)
 
 	for {