faster and more secure junk creation

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.23.6 as awg
+FROM golang:1.24 as awg
 COPY . /awg
 WORKDIR /awg
 RUN go mod download && \

device/device.go

@@ -95,6 +95,7 @@ type Device struct {
 	isASecOn abool.AtomicBool
 	aSecMux  sync.RWMutex
 	aSecCfg  aSecCfgType
+	junkCreator junkCreator
 }
 
 type aSecCfgType struct {
@@ -799,6 +800,7 @@ func (device *Device) handlePostConfig(tempASecCfg *aSecCfgType) (err error) {
 	}
 
 	device.isASecOn.SetTo(isASecOn)
+	device.junkCreator, err = NewJunkCreator(device)
 	device.aSecMux.Unlock()
 
 	return err

device/device_test.go

@@ -109,7 +109,7 @@ func genASecurityConfigs(tb testing.TB) (cfgs, endpointCfgs [2]string) {
 		"replace_peers", "true",
 		"jc", "5",
 		"jmin", "500",
-		"jmax", "501",
+		"jmax", "1000",
 		"s1", "30",
 		"s2", "40",
 		"h1", "123456",
@@ -131,7 +131,7 @@ func genASecurityConfigs(tb testing.TB) (cfgs, endpointCfgs [2]string) {
 		"replace_peers", "true",
 		"jc", "5",
 		"jmin", "500",
-		"jmax", "501",
+		"jmax", "1000",
 		"s1", "30",
 		"s2", "40",
 		"h1", "123456",
@@ -274,7 +274,7 @@ func TestTwoDevicePing(t *testing.T) {
 	})
 }
 
-func TestTwoDevicePingASecurity(t *testing.T) {
+func TestASecurityTwoDevicePing(t *testing.T) {
 	goroutineLeakCheck(t)
 	pair := genTestPair(t, true, true)
 	t.Run("ping 1.0.0.1", func(t *testing.T) {

device/junk_creator.go

@@ -0,0 +1,69 @@
+package device
+
+import (
+	"bytes"
+	crand "crypto/rand"
+	"fmt"
+	v2 "math/rand/v2"
+)
+
+type junkCreator struct {
+	device   *Device
+	cha8Rand *v2.ChaCha8
+}
+
+func NewJunkCreator(d *Device) (junkCreator, error) {
+	buf := make([]byte, 32)
+	_, err := crand.Read(buf)
+	if err != nil {
+		return junkCreator{}, err
+	}
+	return junkCreator{device: d, cha8Rand: v2.NewChaCha8([32]byte(buf))}, nil
+}
+
+// Should be called with aSecMux RLocked
+func (jc *junkCreator) createJunkPackets() ([][]byte, error) {
+	if jc.device.aSecCfg.junkPacketCount == 0 {
+		return nil, nil
+	}
+
+	junks := make([][]byte, 0, jc.device.aSecCfg.junkPacketCount)
+	for i := 0; i < jc.device.aSecCfg.junkPacketCount; i++ {
+		packetSize := jc.randomPacketSize()
+		junk, err := jc.randomJunkWithSize(packetSize)
+		if err != nil {
+			return nil, fmt.Errorf("Failed to create junk packet: %v", err)
+		}
+		junks = append(junks, junk)
+	}
+	return junks, nil
+}
+
+// Should be called with aSecMux RLocked
+func (jc *junkCreator) randomPacketSize() int {
+	return int(
+		jc.cha8Rand.Uint64()%uint64(
+			jc.device.aSecCfg.junkPacketMaxSize-jc.device.aSecCfg.junkPacketMinSize,
+		),
+	) + jc.device.aSecCfg.junkPacketMinSize
+}
+
+// Should be called with aSecMux RLocked
+func (jc *junkCreator) appendJunk(writer *bytes.Buffer, size int) error {
+	headerJunk, err := jc.randomJunkWithSize(size)
+	if err != nil {
+		return fmt.Errorf("failed to create header junk: %v", err)
+	}
+	_, err = writer.Write(headerJunk)
+	if err != nil {
+		return fmt.Errorf("failed to write header junk: %v", err)
+	}
+	return nil
+}
+
+// Should be called with aSecMux RLocked
+func (jc *junkCreator) randomJunkWithSize(size int) ([]byte, error) {
+	junk := make([]byte, size)
+	_, err := jc.cha8Rand.Read(junk)
+	return junk, err
+}

device/junk_creator_test.go

@@ -0,0 +1,124 @@
+package device
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+
+	"github.com/amnezia-vpn/amneziawg-go/conn/bindtest"
+	"github.com/amnezia-vpn/amneziawg-go/tun/tuntest"
+)
+
+func setUpJunkCreator(t *testing.T) (junkCreator, error) {
+	cfg, _ := genASecurityConfigs(t)
+	tun := tuntest.NewChannelTUN()
+	binds := bindtest.NewChannelBinds()
+	level := LogLevelVerbose
+	dev := NewDevice(
+		tun.TUN(),
+		binds[0],
+		NewLogger(level, ""),
+	)
+
+	if err := dev.IpcSet(cfg[0]); err != nil {
+		t.Errorf("failed to configure device %v", err)
+		dev.Close()
+		return junkCreator{}, err
+	}
+
+	jc, err := NewJunkCreator(dev)
+
+	if err != nil {
+		t.Errorf("failed to create junk creator %v", err)
+		dev.Close()
+		return junkCreator{}, err
+	}
+
+	return jc, nil
+}
+
+func Test_junkCreator_createJunkPackets(t *testing.T) {
+	jc, err := setUpJunkCreator(t)
+	if err != nil {
+		return
+	}
+	t.Run("", func(t *testing.T) {
+		got, err := jc.createJunkPackets()
+		if err != nil {
+			t.Errorf(
+				"junkCreator.createJunkPackets() = %v; failed",
+				err,
+			)
+			return
+		}
+		seen := make(map[string]bool)
+		for _, junk := range got {
+			key := string(junk)
+			if seen[key] {
+				t.Errorf(
+					"junkCreator.createJunkPackets() = %v, duplicate key: %v",
+					got,
+					junk,
+				)
+				return
+			}
+			seen[key] = true
+		}
+	})
+}
+
+func Test_junkCreator_randomJunkWithSize(t *testing.T) {
+	t.Run("", func(t *testing.T) {
+		jc, err := setUpJunkCreator(t)
+		if err != nil {
+			return
+		}
+		r1, _ := jc.randomJunkWithSize(10)
+		r2, _ := jc.randomJunkWithSize(10)
+		fmt.Printf("%v\n%v\n", r1, r2)
+		if bytes.Equal(r1, r2) {
+			t.Errorf("same junks %v", err)
+			jc.device.Close()
+			return
+		}
+	})
+}
+
+func Test_junkCreator_randomPacketSize(t *testing.T) {
+	jc, err := setUpJunkCreator(t)
+	if err != nil {
+		return
+	}
+	for range [30]struct{}{} {
+		t.Run("", func(t *testing.T) {
+			if got := jc.randomPacketSize(); jc.device.aSecCfg.junkPacketMinSize > got ||
+				got > jc.device.aSecCfg.junkPacketMaxSize {
+				t.Errorf(
+					"junkCreator.randomPacketSize() = %v, not between range [%v,%v]",
+					got,
+					jc.device.aSecCfg.junkPacketMinSize,
+					jc.device.aSecCfg.junkPacketMaxSize,
+				)
+			}
+		})
+	}
+}
+
+func Test_junkCreator_appendJunk(t *testing.T) {
+	jc, err := setUpJunkCreator(t)
+	if err != nil {
+		return
+	}
+	t.Run("", func(t *testing.T) {
+		s := "apple"
+		buffer := bytes.NewBuffer([]byte(s))
+		err := jc.appendJunk(buffer, 30)
+		if err != nil &&
+			buffer.Len() != len(s)+30 {
+			t.Errorf("appendWithJunk() size don't match")
+		}
+		read := make([]byte, 50)
+		buffer.Read(read)
+		fmt.Println(string(read))
+	})
+}

device/send.go

@@ -9,7 +9,6 @@ import (
 	"bytes"
 	"encoding/binary"
 	"errors"
-	"math/rand"
 	"net"
 	"os"
 	"sync"
@@ -129,7 +128,7 @@ func (peer *Peer) SendHandshakeInitiation(isRetry bool) error {
 	var junkedHeader []byte
 	if peer.device.isAdvancedSecurityOn() {
 		peer.device.aSecMux.RLock()
-		junks, err := peer.createJunkPackets()
+		junks, err := peer.device.junkCreator.createJunkPackets()
 		peer.device.aSecMux.RUnlock()
 
 		if err != nil {
@@ -150,7 +149,7 @@ func (peer *Peer) SendHandshakeInitiation(isRetry bool) error {
 		if peer.device.aSecCfg.initPacketJunkSize != 0 {
 			buf := make([]byte, 0, peer.device.aSecCfg.initPacketJunkSize)
 			writer := bytes.NewBuffer(buf[:0])
-			err = appendJunk(writer, peer.device.aSecCfg.initPacketJunkSize)
+			err = peer.device.junkCreator.appendJunk(writer, peer.device.aSecCfg.initPacketJunkSize)
 			if err != nil {
 				peer.device.log.Errorf("%v - %v", peer, err)
 				peer.device.aSecMux.RUnlock()
@@ -200,7 +199,7 @@ func (peer *Peer) SendHandshakeResponse() error {
 		if peer.device.aSecCfg.responsePacketJunkSize != 0 {
 			buf := make([]byte, 0, peer.device.aSecCfg.responsePacketJunkSize)
 			writer := bytes.NewBuffer(buf[:0])
-			err = appendJunk(writer, peer.device.aSecCfg.responsePacketJunkSize)
+			err = peer.device.junkCreator.appendJunk(writer, peer.device.aSecCfg.responsePacketJunkSize)
 			if err != nil {
 				peer.device.aSecMux.RUnlock()
 				peer.device.log.Errorf("%v - %v", peer, err)
@@ -469,31 +468,6 @@ top:
 	}
 }
 
-func (peer *Peer) createJunkPackets() ([][]byte, error) {
-	if peer.device.aSecCfg.junkPacketCount == 0 {
-		return nil, nil
-	}
-
-	junks := make([][]byte, 0, peer.device.aSecCfg.junkPacketCount)
-	for i := 0; i < peer.device.aSecCfg.junkPacketCount; i++ {
-		packetSize := rand.Intn(
-			peer.device.aSecCfg.junkPacketMaxSize-peer.device.aSecCfg.junkPacketMinSize,
-		) + peer.device.aSecCfg.junkPacketMinSize
-
-		junk, err := randomJunkWithSize(packetSize)
-		if err != nil {
-			peer.device.log.Errorf(
-				"%v - Failed to create junk packet: %v",
-				peer,
-				err,
-			)
-			return nil, err
-		}
-		junks = append(junks, junk)
-	}
-	return junks, nil
-}
-
 func (peer *Peer) FlushStagedPackets() {
 	for {
 		select {

device/util.go

@@ -1,25 +0,0 @@
-package device
-
-import (
-	"bytes"
-	crand "crypto/rand"
-	"fmt"
-)
-
-func appendJunk(writer *bytes.Buffer, size int) error {
-	headerJunk, err := randomJunkWithSize(size)
-	if err != nil {
-		return fmt.Errorf("failed to create header junk: %v", err)
-	}
-	_, err = writer.Write(headerJunk)
-	if err != nil {
-		return fmt.Errorf("failed to write header junk: %v", err)
-	}
-	return nil
-}
-
-func randomJunkWithSize(size int) ([]byte, error) {
-	junk := make([]byte, size)
-	_, err := crand.Read(junk)
-	return junk, err
-}

device/util_test.go

@@ -1,27 +0,0 @@
-package device
-
-import (
-	"bytes"
-	"fmt"
-	"testing"
-)
-
-func Test_randomJunktWithSize(t *testing.T) {
-	junk, err := randomJunkWithSize(30)
-	fmt.Println(string(junk), len(junk), err)
-}
-
-func Test_appendJunk(t *testing.T) {
-	t.Run("", func(t *testing.T) {
-		s := "apple"
-		buffer := bytes.NewBuffer([]byte(s))
-		err := appendJunk(buffer, 30)
-		if err != nil &&
-			buffer.Len() != len(s)+30 {
-			t.Errorf("appendWithJunk() size don't match")
-		}
-		read := make([]byte, 50)
-		buffer.Read(read)
-		fmt.Println(string(read))
-	})
-}

go.mod

@@ -1,12 +1,12 @@
 module github.com/amnezia-vpn/amneziawg-go
 
-go 1.23.6
+go 1.24
 
 require (
 	github.com/tevino/abool/v2 v2.1.0
-	golang.org/x/crypto v0.32.0
+	golang.org/x/crypto v0.36.0
-	golang.org/x/net v0.34.0
+	golang.org/x/net v0.37.0
-	golang.org/x/sys v0.29.0
+	golang.org/x/sys v0.31.0
 	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2
 	gvisor.dev/gvisor v0.0.0-20250130013005-04f9204697c6
 )

go.sum

@@ -4,14 +4,14 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/tevino/abool/v2 v2.1.0 h1:7w+Vf9f/5gmKT4m4qkayb33/92M+Um45F2BkHOR+L/c=
 github.com/tevino/abool/v2 v2.1.0/go.mod h1:+Lmlqk6bHDWHqN1cbxqhwEAwMPXgc8I1SDEamtseuXY=
-golang.org/x/crypto v0.32.0 h1:euUpcYgM8WcP71gNpTqQCn6rC2t6ULUPiOzfWaXVVfc=
+golang.org/x/crypto v0.36.0 h1:AnAEvhDddvBdpY+uR+MyHmuZzzNqXSe/GvuDeob5L34=
-golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
+golang.org/x/crypto v0.36.0/go.mod h1:Y4J0ReaxCR1IMaabaSMugxJES1EpwhBHhv2bDHklZvc=
 golang.org/x/mod v0.21.0 h1:vvrHzRwRfVKSiLrG+d4FMl/Qi4ukBCE6kZlTUkDYRT0=
 golang.org/x/mod v0.21.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
-golang.org/x/net v0.34.0 h1:Mb7Mrk043xzHgnRM88suvJFwzVrRfHEHJEl5/71CKw0=
+golang.org/x/net v0.37.0 h1:1zLorHbz+LYj7MQlSf1+2tPIIgibq2eL5xkrGk6f+2c=
-golang.org/x/net v0.34.0/go.mod h1:di0qlW3YNM5oh6GqDGQr92MyTozJPmybPK4Ev/Gm31k=
+golang.org/x/net v0.37.0/go.mod h1:ivrbrMbzFq5J41QOQh0siUuly180yBYtLp+CKbEaFx8=
-golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
+golang.org/x/sys v0.31.0 h1:ioabZlmFYtWhL+TRYpcnNlLwhyxaM9kWTDEmfnprqik=
-golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.31.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
 golang.org/x/time v0.9.0 h1:EsRrnYcQiGH+5FfbgvV4AP7qEZstoyrHB0DzarOQ4ZY=
 golang.org/x/time v0.9.0/go.mod h1:3BpzKBy/shNhVucY/MWOyx10tF3SFh9QdLuxbVysPQM=
 golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 h1:B82qJJgjvYKsXS9jeunTOisW56dUokqW/FOteYJJ/yg=