device: make test setup more robust

Picking two free ports to use for a test is difficult.
The free port we selected might no longer be free when we reach
for it a second time.

On my machine, this failure mode led to failures approximately
once per thousand test runs.

Since failures are rare, and threading through and checking for
all possible errors is complicated, fix this with a big hammer:
Retry if either device fails to come up.

Also, if you accidentally pick the same port twice, delightful confusion ensues.
The handshake failures manifest as crypto errors, which look scary.
Again, fix with retries.

To make these retries easier to implement, use testing.T.Cleanup
instead of defer to close devices. This requires Go 1.14.
Update go.mod accordingly. Go 1.13 is no longer supported anyway.

With these fixes, 'go test -race' ran 100,000 times without failure.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This commit is contained in:
Josh Bleecher Snyder 2020-12-08 19:23:56 -08:00 committed by Jason A. Donenfeld
parent ca9edf1c63
commit 3591acba76
2 changed files with 65 additions and 29 deletions

View file

@ -26,11 +26,11 @@ func getFreePort(t *testing.T) string {
return fmt.Sprintf("%d", l.LocalAddr().(*net.UDPAddr).Port) return fmt.Sprintf("%d", l.LocalAddr().(*net.UDPAddr).Port)
} }
func TestTwoDevicePing(t *testing.T) { // genConfigs generates a pair of configs that connect to each other.
port1 := getFreePort(t) // The configs use distinct, probably-usable ports.
port2 := getFreePort(t) func genConfigs(t *testing.T) (cfgs [2]*bufio.Reader) {
const (
cfg1 := `private_key=481eb0d8113a4a5da532d2c3e9c14b53c8454b34ab109676f6b58c2245e37b58 cfg1 = `private_key=481eb0d8113a4a5da532d2c3e9c14b53c8454b34ab109676f6b58c2245e37b58
listen_port={{PORT1}} listen_port={{PORT1}}
replace_peers=true replace_peers=true
public_key=f70dbb6b1b92a1dde1c783b297016af3f572fef13b0abb16a2623d89a58e9725 public_key=f70dbb6b1b92a1dde1c783b297016af3f572fef13b0abb16a2623d89a58e9725
@ -38,18 +38,8 @@ protocol_version=1
replace_allowed_ips=true replace_allowed_ips=true
allowed_ip=1.0.0.2/32 allowed_ip=1.0.0.2/32
endpoint=127.0.0.1:{{PORT2}}` endpoint=127.0.0.1:{{PORT2}}`
cfg1 = strings.ReplaceAll(cfg1, "{{PORT1}}", port1)
cfg1 = strings.ReplaceAll(cfg1, "{{PORT2}}", port2)
tun1 := tuntest.NewChannelTUN() cfg2 = `private_key=98c7989b1661a0d64fd6af3502000f87716b7c4bbcf00d04fc6073aa7b539768
dev1 := NewDevice(tun1.TUN(), NewLogger(LogLevelDebug, "dev1: "))
dev1.Up()
defer dev1.Close()
if err := dev1.IpcSetOperation(bufio.NewReader(strings.NewReader(cfg1))); err != nil {
t.Fatal(err)
}
cfg2 := `private_key=98c7989b1661a0d64fd6af3502000f87716b7c4bbcf00d04fc6073aa7b539768
listen_port={{PORT2}} listen_port={{PORT2}}
replace_peers=true replace_peers=true
public_key=49e80929259cebdda4f322d6d2b1a6fad819d603acd26fd5d845e7a123036427 public_key=49e80929259cebdda4f322d6d2b1a6fad819d603acd26fd5d845e7a123036427
@ -57,22 +47,68 @@ protocol_version=1
replace_allowed_ips=true replace_allowed_ips=true
allowed_ip=1.0.0.1/32 allowed_ip=1.0.0.1/32
endpoint=127.0.0.1:{{PORT1}}` endpoint=127.0.0.1:{{PORT1}}`
cfg2 = strings.ReplaceAll(cfg2, "{{PORT1}}", port1) )
cfg2 = strings.ReplaceAll(cfg2, "{{PORT2}}", port2)
tun2 := tuntest.NewChannelTUN() var port1, port2 string
dev2 := NewDevice(tun2.TUN(), NewLogger(LogLevelDebug, "dev2: ")) for port1 == port2 {
dev2.Up() port1 = getFreePort(t)
defer dev2.Close() port2 = getFreePort(t)
if err := dev2.IpcSetOperation(bufio.NewReader(strings.NewReader(cfg2))); err != nil {
t.Fatal(err)
} }
for i, cfg := range []string{cfg1, cfg2} {
cfg = strings.ReplaceAll(cfg, "{{PORT1}}", port1)
cfg = strings.ReplaceAll(cfg, "{{PORT2}}", port2)
cfgs[i] = bufio.NewReader(strings.NewReader(cfg))
}
return
}
// genChannelTUNs creates a usable pair of ChannelTUNs for use in a test.
func genChannelTUNs(t *testing.T) (tun [2]*tuntest.ChannelTUN) {
const maxAttempts = 10
NextAttempt:
for i := 0; i < maxAttempts; i++ {
cfg := genConfigs(t)
// Bring up a ChannelTun for each config.
for i := range tun {
tun[i] = tuntest.NewChannelTUN()
dev := NewDevice(tun[i].TUN(), NewLogger(LogLevelDebug, fmt.Sprintf("dev%d: ", i)))
dev.Up()
if err := dev.IpcSetOperation(cfg[i]); err != nil {
// genConfigs attempted to pick ports that were free.
// There's a tiny window between genConfigs closing the port
// and us opening it, during which another process could
// start using it. We probably just lost that race.
// Try again from the beginning.
// If there's something permanent wrong,
// we'll see that when we run out of attempts.
t.Logf("failed to configure device %d: %v", i, err)
continue NextAttempt
}
// The device might still not be up, e.g. due to an error
// in RoutineTUNEventReader's call to dev.Up that got swallowed.
// Assume it's due to a transient error (port in use), and retry.
if !dev.isUp.Get() {
t.Logf("%v did not come up, trying again", dev)
continue NextAttempt
}
// The device is up. Close it when the test completes.
t.Cleanup(dev.Close)
}
return // success
}
t.Fatalf("genChannelTUNs: failed %d times", maxAttempts)
return
}
func TestTwoDevicePing(t *testing.T) {
tun := genChannelTUNs(t)
t.Run("ping 1.0.0.1", func(t *testing.T) { t.Run("ping 1.0.0.1", func(t *testing.T) {
msg2to1 := tuntest.Ping(net.ParseIP("1.0.0.1"), net.ParseIP("1.0.0.2")) msg2to1 := tuntest.Ping(net.ParseIP("1.0.0.1"), net.ParseIP("1.0.0.2"))
tun2.Outbound <- msg2to1 tun[1].Outbound <- msg2to1
select { select {
case msgRecv := <-tun1.Inbound: case msgRecv := <-tun[0].Inbound:
if !bytes.Equal(msg2to1, msgRecv) { if !bytes.Equal(msg2to1, msgRecv) {
t.Error("ping did not transit correctly") t.Error("ping did not transit correctly")
} }
@ -83,9 +119,9 @@ endpoint=127.0.0.1:{{PORT1}}`
t.Run("ping 1.0.0.2", func(t *testing.T) { t.Run("ping 1.0.0.2", func(t *testing.T) {
msg1to2 := tuntest.Ping(net.ParseIP("1.0.0.2"), net.ParseIP("1.0.0.1")) msg1to2 := tuntest.Ping(net.ParseIP("1.0.0.2"), net.ParseIP("1.0.0.1"))
tun1.Outbound <- msg1to2 tun[0].Outbound <- msg1to2
select { select {
case msgRecv := <-tun2.Inbound: case msgRecv := <-tun[1].Inbound:
if !bytes.Equal(msg1to2, msgRecv) { if !bytes.Equal(msg1to2, msgRecv) {
t.Error("return ping did not transit correctly") t.Error("return ping did not transit correctly")
} }

2
go.mod
View file

@ -1,6 +1,6 @@
module golang.zx2c4.com/wireguard module golang.zx2c4.com/wireguard
go 1.13 go 1.14
require ( require (
golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392 golang.org/x/crypto v0.0.0-20201124201722-c8d3bf9c5392