feat: support client verify for derp (add integration tests) (#2046)

* feat: support client verify for derp

* docs: fix doc for integration test

* tests: add integration test for DERP verify endpoint

* tests: use `tailcfg.DERPMap` instead of `[]byte`

* refactor: introduce func `ContainsNodeKey`

* tests(dsic): use string builder for cmd args

* ci: fix tests order

* tests: fix derper failure

* chore: cleanup

* tests(verify-client): perfer to use `CreateHeadscaleEnv`

* refactor(verify-client): simplify error handling

* tests: fix `TestDERPVerifyEndpoint`

* refactor: make `doVerify` a seperated func

---------

Co-authored-by: 117503445 <t117503445@gmail.com>

integration/derp_verify_endpoint_test.go

@@ -0,0 +1,96 @@
+package integration
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/juanfont/headscale/hscontrol/util"
+	"github.com/juanfont/headscale/integration/dsic"
+	"github.com/juanfont/headscale/integration/hsic"
+	"github.com/juanfont/headscale/integration/integrationutil"
+	"github.com/juanfont/headscale/integration/tsic"
+	"tailscale.com/tailcfg"
+)
+
+func TestDERPVerifyEndpoint(t *testing.T) {
+	IntegrationSkip(t)
+
+	// Generate random hostname for the headscale instance
+	hash, err := util.GenerateRandomStringDNSSafe(6)
+	assertNoErr(t, err)
+	testName := "derpverify"
+	hostname := fmt.Sprintf("hs-%s-%s", testName, hash)
+
+	headscalePort := 8080
+
+	// Create cert for headscale
+	certHeadscale, keyHeadscale, err := integrationutil.CreateCertificate(hostname)
+	assertNoErr(t, err)
+
+	scenario, err := NewScenario(dockertestMaxWait())
+	assertNoErr(t, err)
+	defer scenario.ShutdownAssertNoPanics(t)
+
+	spec := map[string]int{
+		"user1": len(MustTestVersions),
+	}
+
+	derper, err := scenario.CreateDERPServer("head",
+		dsic.WithCACert(certHeadscale),
+		dsic.WithVerifyClientURL(fmt.Sprintf("https://%s/verify", net.JoinHostPort(hostname, strconv.Itoa(headscalePort)))),
+	)
+	assertNoErr(t, err)
+
+	derpMap := tailcfg.DERPMap{
+		Regions: map[int]*tailcfg.DERPRegion{
+			900: {
+				RegionID:   900,
+				RegionCode: "test-derpverify",
+				RegionName: "TestDerpVerify",
+				Nodes: []*tailcfg.DERPNode{
+					{
+						Name:     "TestDerpVerify",
+						RegionID: 900,
+						HostName: derper.GetHostname(),
+						STUNPort: derper.GetSTUNPort(),
+						STUNOnly: false,
+						DERPPort: derper.GetDERPPort(),
+					},
+				},
+			},
+		},
+	}
+
+	err = scenario.CreateHeadscaleEnv(spec, []tsic.Option{tsic.WithCACert(derper.GetCert())},
+		hsic.WithHostname(hostname),
+		hsic.WithPort(headscalePort),
+		hsic.WithCustomTLS(certHeadscale, keyHeadscale),
+		hsic.WithHostnameAsServerURL(),
+		hsic.WithDERPConfig(derpMap))
+	assertNoErrHeadscaleEnv(t, err)
+
+	allClients, err := scenario.ListTailscaleClients()
+	assertNoErrListClients(t, err)
+
+	for _, client := range allClients {
+		report, err := client.DebugDERPRegion("test-derpverify")
+		assertNoErr(t, err)
+		successful := false
+		for _, line := range report.Info {
+			if strings.Contains(line, "Successfully established a DERP connection with node") {
+				successful = true
+
+				break
+			}
+		}
+		if !successful {
+			stJSON, err := json.Marshal(report)
+			assertNoErr(t, err)
+			t.Errorf("Client %s could not establish a DERP connection: %s", client.Hostname(), string(stJSON))
+		}
+	}
+}