tstest/integration/vms: add in-process DERP server (#2108)

Previously this test would reach out to the public DERP servers in order
to help machines connect with eachother. This is not ideal given our
plans to run these tests completely disconnected from the internet. This
patch introduces an in-process DERP server running on its own randomly
assigned HTTP port.

Updates #1988

Signed-off-by: Christine Dodrill <xe@tailscale.com>

tstest/integration/integration_test.go

@@ -7,8 +7,6 @@ package integration
 import (
 	"bytes"
 	"context"
-	crand "crypto/rand"
-	"crypto/tls"
 	"encoding/json"
 	"errors"
 	"flag"
@@ -16,7 +14,6 @@ import (
 	"io"
 	"io/ioutil"
 	"log"
-	"net"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -31,18 +28,13 @@ import (
 	"time"
 
 	"go4.org/mem"
-	"tailscale.com/derp"
-	"tailscale.com/derp/derphttp"
 	"tailscale.com/ipn/ipnstate"
-	"tailscale.com/net/stun/stuntest"
 	"tailscale.com/safesocket"
 	"tailscale.com/smallzstd"
 	"tailscale.com/tailcfg"
 	"tailscale.com/tstest"
 	"tailscale.com/tstest/integration/testcontrol"
-	"tailscale.com/types/key"
 	"tailscale.com/types/logger"
-	"tailscale.com/types/nettype"
 )
 
 var (
@@ -301,8 +293,6 @@ type testEnv struct {
 
 	TrafficTrap       *trafficTrap
 	TrafficTrapServer *httptest.Server
-
-	derpShutdown func()
 }
 
 type testEnvOpt interface {
@@ -323,7 +313,7 @@ func newTestEnv(t testing.TB, bins *Binaries, opts ...testEnvOpt) *testEnv {
 	if runtime.GOOS == "windows" {
 		t.Skip("not tested/working on Windows yet")
 	}
-	derpMap, derpShutdown := runDERPAndStun(t, logger.Discard)
+	derpMap := RunDERPAndSTUN(t, logger.Discard, "127.0.0.1")
 	logc := new(logCatcher)
 	control := &testcontrol.Server{
 		DERPMap: derpMap,
@@ -339,7 +329,6 @@ func newTestEnv(t testing.TB, bins *Binaries, opts ...testEnvOpt) *testEnv {
 		ControlServer:     control.HTTPTestServer,
 		TrafficTrap:       trafficTrap,
 		TrafficTrapServer: httptest.NewServer(trafficTrap),
-		derpShutdown:      derpShutdown,
 	}
 	for _, o := range opts {
 		o.modifyTestEnv(e)
@@ -357,7 +346,6 @@ func (e *testEnv) Close() error {
 	e.LogCatcherServer.Close()
 	e.TrafficTrapServer.Close()
 	e.ControlServer.Close()
-	e.derpShutdown()
 	return nil
 }
 
@@ -620,51 +608,6 @@ func (tt *trafficTrap) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(403)
 }
 
-func runDERPAndStun(t testing.TB, logf logger.Logf) (derpMap *tailcfg.DERPMap, cleanup func()) {
-	var serverPrivateKey key.Private
-	if _, err := crand.Read(serverPrivateKey[:]); err != nil {
-		t.Fatal(err)
-	}
-	d := derp.NewServer(serverPrivateKey, logf)
-
-	httpsrv := httptest.NewUnstartedServer(derphttp.Handler(d))
-	httpsrv.Config.ErrorLog = logger.StdLogger(logf)
-	httpsrv.Config.TLSNextProto = make(map[string]func(*http.Server, *tls.Conn, http.Handler))
-	httpsrv.StartTLS()
-
-	stunAddr, stunCleanup := stuntest.ServeWithPacketListener(t, nettype.Std{})
-
-	m := &tailcfg.DERPMap{
-		Regions: map[int]*tailcfg.DERPRegion{
-			1: {
-				RegionID:   1,
-				RegionCode: "test",
-				Nodes: []*tailcfg.DERPNode{
-					{
-						Name:         "t1",
-						RegionID:     1,
-						HostName:     "127.0.0.1", // to bypass HTTP proxy
-						IPv4:         "127.0.0.1",
-						IPv6:         "none",
-						STUNPort:     stunAddr.Port,
-						DERPTestPort: httpsrv.Listener.Addr().(*net.TCPAddr).Port,
-						STUNTestIP:   stunAddr.IP.String(),
-					},
-				},
-			},
-		},
-	}
-
-	cleanup = func() {
-		httpsrv.CloseClientConnections()
-		httpsrv.Close()
-		d.Close()
-		stunCleanup()
-	}
-
-	return m, cleanup
-}
-
 type authURLParserWriter struct {
 	buf bytes.Buffer
 	fn  func(urlStr string) error