tstest/integration/vms: split up test framework into files (#2396)

My spatial memory functions poorly with large files and the vms_test.go
file recently surpassed the point where it functions adequately. This
patch splits up vms_test.go into more files to make my spatial memory
function like I need it to.

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

tstest/integration/vms/harness_test.go

@@ -0,0 +1,125 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux
+
+package vms
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"net"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/gliderlabs/ssh"
+	"golang.org/x/net/proxy"
+	"inet.af/netaddr"
+	"tailscale.com/tstest/integration"
+	"tailscale.com/tstest/integration/testcontrol"
+)
+
+type Harness struct {
+	testerDialer   proxy.Dialer
+	testerDir      string
+	bins           *integration.Binaries
+	signer         ssh.Signer
+	cs             *testcontrol.Server
+	loginServerURL string
+	testerV4       netaddr.IP
+}
+
+func (h *Harness) Tailscale(t *testing.T, args ...string) []byte {
+	t.Helper()
+
+	args = append([]string{"--socket=" + filepath.Join(h.testerDir, "sock")}, args...)
+
+	cmd := exec.Command(h.bins.CLI, args...)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return out
+}
+
+// makeTestNode creates a userspace tailscaled running in netstack mode that
+// enables us to make connections to and from the tailscale network being
+// tested. This mutates the Harness to allow tests to dial into the tailscale
+// network as well as control the tester's tailscaled.
+func (h *Harness) makeTestNode(t *testing.T, bins *integration.Binaries, controlURL string) {
+	dir := t.TempDir()
+	h.testerDir = dir
+
+	port, err := getProbablyFreePortNumber()
+	if err != nil {
+		t.Fatalf("can't get free port: %v", err)
+	}
+
+	cmd := exec.Command(
+		bins.Daemon,
+		"--tun=userspace-networking",
+		"--state="+filepath.Join(dir, "state.json"),
+		"--socket="+filepath.Join(dir, "sock"),
+		fmt.Sprintf("--socks5-server=localhost:%d", port),
+	)
+
+	cmd.Env = append(
+		os.Environ(),
+		"NOTIFY_SOCKET="+filepath.Join(dir, "notify_socket"),
+		"TS_LOG_TARGET="+h.loginServerURL,
+	)
+
+	err = cmd.Start()
+	if err != nil {
+		t.Fatalf("can't start tailscaled: %v", err)
+	}
+
+	t.Cleanup(func() {
+		cmd.Process.Kill()
+	})
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	ticker := time.NewTicker(100 * time.Millisecond)
+
+outer:
+	for {
+		select {
+		case <-ctx.Done():
+			t.Fatal("timed out waiting for tailscaled to come up")
+			return
+		case <-ticker.C:
+			conn, err := net.Dial("unix", filepath.Join(dir, "sock"))
+			if err != nil {
+				continue
+			}
+
+			conn.Close()
+			break outer
+		}
+	}
+
+	run(t, dir, bins.CLI,
+		"--socket="+filepath.Join(dir, "sock"),
+		"up",
+		"--login-server="+controlURL,
+		"--hostname=tester",
+	)
+
+	dialer, err := proxy.SOCKS5("tcp", net.JoinHostPort("127.0.0.1", fmt.Sprint(port)), nil, &net.Dialer{})
+	if err != nil {
+		t.Fatalf("can't make netstack proxy dialer: %v", err)
+	}
+	h.testerDialer = dialer
+	h.testerV4 = bytes2Netaddr(h.Tailscale(t, "ip", "-4"))
+}
+
+func bytes2Netaddr(inp []byte) netaddr.IP {
+	return netaddr.MustParseIP(string(bytes.TrimSpace(inp)))
+}