device: test up/down using virtual conn

This prevents port clashing bugs.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 155 insertions, 24 deletions

diff --git a/conn/bindtest/bindtest.go b/conn/bindtest/bindtest.go
new file mode 100644
index 0000000..ad8fa05
--- /dev/null
+++ b/conn/bindtest/bindtest.go
@@ -0,0 +1,136 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019-2021 WireGuard LLC. All Rights Reserved.
+ */
+
+package bindtest
+
+import (
+	"fmt"
+	"math/rand"
+	"net"
+	"os"
+	"strconv"
+
+	"golang.zx2c4.com/wireguard/conn"
+)
+
+type ChannelBind struct {
+	rx4, tx4         *chan []byte
+	rx6, tx6         *chan []byte
+	closeSignal      chan bool
+	source4, source6 ChannelEndpoint
+	target4, target6 ChannelEndpoint
+}
+
+type ChannelEndpoint uint16
+
+var _ conn.Bind = (*ChannelBind)(nil)
+var _ conn.Endpoint = (*ChannelEndpoint)(nil)
+
+func NewChannelBinds() [2]conn.Bind {
+	arx4 := make(chan []byte, 8192)
+	brx4 := make(chan []byte, 8192)
+	arx6 := make(chan []byte, 8192)
+	brx6 := make(chan []byte, 8192)
+	var binds [2]ChannelBind
+	binds[0].rx4 = &arx4
+	binds[0].tx4 = &brx4
+	binds[1].rx4 = &brx4
+	binds[1].tx4 = &arx4
+	binds[0].rx6 = &arx6
+	binds[0].tx6 = &brx6
+	binds[1].rx6 = &brx6
+	binds[1].tx6 = &arx6
+	binds[0].target4 = ChannelEndpoint(1)
+	binds[1].target4 = ChannelEndpoint(2)
+	binds[0].target6 = ChannelEndpoint(3)
+	binds[1].target6 = ChannelEndpoint(4)
+	binds[0].source4 = binds[1].target4
+	binds[0].source6 = binds[1].target6
+	binds[1].source4 = binds[0].target4
+	binds[1].source6 = binds[0].target6
+	return [2]conn.Bind{&binds[0], &binds[1]}
+}
+
+func (c ChannelEndpoint) ClearSrc() {}
+
+func (c ChannelEndpoint) SrcToString() string { return "" }
+
+func (c ChannelEndpoint) DstToString() string { return fmt.Sprintf("127.0.0.1:%d", c) }
+
+func (c ChannelEndpoint) DstToBytes() []byte { return []byte{byte(c)} }
+
+func (c ChannelEndpoint) DstIP() net.IP { return net.IPv4(127, 0, 0, 1) }
+
+func (c ChannelEndpoint) SrcIP() net.IP { return nil }
+
+func (c *ChannelBind) Open(port uint16) (actualPort uint16, err error) {
+	c.closeSignal = make(chan bool)
+	if rand.Uint32()&1 == 0 {
+		return uint16(c.source4), nil
+	} else {
+		return uint16(c.source6), nil
+	}
+}
+
+func (c *ChannelBind) Close() error {
+	if c.closeSignal != nil {
+		select {
+		case <-c.closeSignal:
+		default:
+			close(c.closeSignal)
+		}
+	}
+	return nil
+}
+
+func (c *ChannelBind) SetMark(mark uint32) error { return nil }
+
+func (c *ChannelBind) ReceiveIPv6(b []byte) (n int, ep conn.Endpoint, err error) {
+	select {
+	case <-c.closeSignal:
+		return 0, nil, net.ErrClosed
+	case rx := <-*c.rx6:
+		return copy(b, rx), c.target6, nil
+	}
+}
+
+func (c *ChannelBind) ReceiveIPv4(b []byte) (n int, ep conn.Endpoint, err error) {
+	select {
+	case <-c.closeSignal:
+		return 0, nil, net.ErrClosed
+	case rx := <-*c.rx4:
+		return copy(b, rx), c.target4, nil
+	}
+}
+
+func (c *ChannelBind) Send(b []byte, ep conn.Endpoint) error {
+	select {
+	case <-c.closeSignal:
+		return net.ErrClosed
+	default:
+		bc := make([]byte, len(b))
+		copy(bc, b)
+		if ep.(ChannelEndpoint) == c.target4 {
+			*c.tx4 <- bc
+		} else if ep.(ChannelEndpoint) == c.target6 {
+			*c.tx6 <- bc
+		} else {
+			return os.ErrInvalid
+		}
+	}
+	return nil
+}
+
+func (c *ChannelBind) ParseEndpoint(s string) (conn.Endpoint, error) {
+	_, port, err := net.SplitHostPort(s)
+	if err != nil {
+		return nil, err
+	}
+	i, err := strconv.ParseUint(port, 10, 16)
+	if err != nil {
+		return nil, err
+	}
+	return ChannelEndpoint(i), nil
+}
diff --git a/device/device_test.go b/device/device_test.go
index 1716f92..29daeb9 100644
--- a/device/device_test.go
+++ b/device/device_test.go
@@ -8,7 +8,6 @@ package device
 import (
 	"bytes"
 	"encoding/hex"
-	"errors"
 	"fmt"
 	"io"
 	"math/rand"
@@ -17,11 +16,11 @@ import (
 	"runtime/pprof"
 	"sync"
 	"sync/atomic"
-	"syscall"
 	"testing"
 	"time"
 
 	"golang.zx2c4.com/wireguard/conn"
+	"golang.zx2c4.com/wireguard/conn/bindtest"
 	"golang.zx2c4.com/wireguard/tun/tuntest"
 )
 
@@ -148,8 +147,14 @@ func (pair *testPair) Send(tb testing.TB, ping SendDirection, done chan struct{}
 }
 
 // genTestPair creates a testPair.
-func genTestPair(tb testing.TB) (pair testPair) {
+func genTestPair(tb testing.TB, realSocket bool) (pair testPair) {
 	cfg, endpointCfg := genConfigs(tb)
+	var binds [2]conn.Bind
+	if realSocket {
+		binds[0], binds[1] = conn.NewDefaultBind(), conn.NewDefaultBind()
+	} else {
+		binds = bindtest.NewChannelBinds()
+	}
 	// Bring up a ChannelTun for each config.
 	for i := range pair {
 		p := &pair[i]
@@ -159,7 +164,7 @@ func genTestPair(tb testing.TB) (pair testPair) {
 		if _, ok := tb.(*testing.B); ok && !testing.Verbose() {
 			level = LogLevelError
 		}
-		p.dev = NewDevice(p.tun.TUN(), conn.NewDefaultBind(), NewLogger(level, fmt.Sprintf("dev%d: ", i)))
+		p.dev = NewDevice(p.tun.TUN(), binds[i], NewLogger(level, fmt.Sprintf("dev%d: ", i)))
 		if err := p.dev.IpcSet(cfg[i]); err != nil {
 			tb.Errorf("failed to configure device %d: %v", i, err)
 			p.dev.Close()
@@ -187,7 +192,7 @@ func genTestPair(tb testing.TB) (pair testPair) {
 
 func TestTwoDevicePing(t *testing.T) {
 	goroutineLeakCheck(t)
-	pair := genTestPair(t)
+	pair := genTestPair(t, true)
 	t.Run("ping 1.0.0.1", func(t *testing.T) {
 		pair.Send(t, Ping, nil)
 	})
@@ -198,11 +203,11 @@ func TestTwoDevicePing(t *testing.T) {
 
 func TestUpDown(t *testing.T) {
 	goroutineLeakCheck(t)
-	const itrials = 20
-	const otrials = 1
+	const itrials = 50
+	const otrials = 10
 
 	for n := 0; n < otrials; n++ {
-		pair := genTestPair(t)
+		pair := genTestPair(t, false)
 		for i := range pair {
 			for k := range pair[i].dev.peers.keyMap {
 				pair[i].dev.IpcSet(fmt.Sprintf("public_key=%s\npersistent_keepalive_interval=1\n", hex.EncodeToString(k[:])))
@@ -214,17 +219,8 @@ func TestUpDown(t *testing.T) {
 			go func(d *Device) {
 				defer wg.Done()
 				for i := 0; i < itrials; i++ {
-					start := time.Now()
-					for {
-						if err := d.Up(); err != nil {
-							if errors.Is(err, syscall.EADDRINUSE) && time.Now().Sub(start) < time.Second*4 {
-								// Some other test process is racing with us, so try again.
-								time.Sleep(time.Millisecond * 10)
-								continue
-							}
-							t.Errorf("failed up bring up device: %v", err)
-						}
-						break
+					if err := d.Up(); err != nil {
+						t.Errorf("failed up bring up device: %v", err)
 					}
 					time.Sleep(time.Duration(rand.Intn(int(time.Nanosecond * (0x10000 - 1)))))
 					if err := d.Down(); err != nil {
@@ -245,7 +241,7 @@ func TestUpDown(t *testing.T) {
 // TestConcurrencySafety does other things concurrently with tunnel use.
 // It is intended to be used with the race detector to catch data races.
 func TestConcurrencySafety(t *testing.T) {
-	pair := genTestPair(t)
+	pair := genTestPair(t, true)
 	done := make(chan struct{})
 
 	const warmupIters = 10
@@ -315,7 +311,7 @@ func TestConcurrencySafety(t *testing.T) {
 }
 
 func BenchmarkLatency(b *testing.B) {
-	pair := genTestPair(b)
+	pair := genTestPair(b, true)
 
 	// Establish a connection.
 	pair.Send(b, Ping, nil)
@@ -329,7 +325,7 @@ func BenchmarkLatency(b *testing.B) {
 }
 
 func BenchmarkThroughput(b *testing.B) {
-	pair := genTestPair(b)
+	pair := genTestPair(b, true)
 
 	// Establish a connection.
 	pair.Send(b, Ping, nil)
@@ -373,7 +369,7 @@ func BenchmarkThroughput(b *testing.B) {
 }
 
 func BenchmarkUAPIGet(b *testing.B) {
-	pair := genTestPair(b)
+	pair := genTestPair(b, true)
 	pair.Send(b, Ping, nil)
 	pair.Send(b, Pong, nil)
 	b.ReportAllocs()
diff --git a/tun/tuntest/tuntest.go b/tun/tuntest/tuntest.go
index 80ccdf9..92aa9d8 100644
--- a/tun/tuntest/tuntest.go
+++ b/tun/tuntest/tuntest.go
@@ -79,7 +79,6 @@ func genICMPv4(payload []byte, dst, src net.IP) []byte {
 	return pkt
 }
 
-// TODO(crawshaw): find a reusable home for this. package devicetest?
 type ChannelTUN struct {
 	Inbound  chan []byte // incoming packets, closed on TUN close
 	Outbound chan []byte // outbound packets, blocks forever on TUN close