Mask target config on the source detail page (closes #113)

The page rendered the stored target config verbatim, exposing the Slack
incoming-webhook URL, which is a bearer credential: anyone holding it can
post to the channel indefinitely, and it cannot be scoped or revoked
per-holder.

Target config now reaches the template only as a TargetView carrying
labelled fields, so no code path can render the raw blob. maskURL keeps
scheme and host and elides the path, and drops query, fragment and
userinfo; every parse failure yields a neutral placeholder rather than
falling back to the stored string. HTTP header values are never rendered,
only a count.

Rendering change only: the stored config format and the delivery path are
unchanged.

internal/handlers/source_detail_test.go

@@ -0,0 +1,185 @@
+package handlers_test
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/go-chi/chi"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/gorm/clause"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/handlers"
+	"sneak.berlin/go/webhooker/internal/session"
+)
+
+// The secret path segments of a Slack incoming webhook URL.
+// Holding them is enough to post to the channel forever, so
+// they must never reach the rendered page.
+const (
+	slackSecretPath = "/services/T00000000/B00000000/" +
+		"XXXXXXXXXXXXXXXXXXXXXXXX"
+	slackWebhookURL = "https://hooks.slack.com" +
+		slackSecretPath
+)
+
+// seedConfiguredTarget inserts a target with a stored config
+// blob.
+func seedConfiguredTarget(
+	t *testing.T,
+	db *database.Database,
+	webhookID string,
+	targetType database.TargetType,
+	config string,
+) {
+	t.Helper()
+
+	tgt := &database.Target{
+		WebhookID: webhookID,
+		Name:      "t-" + string(targetType),
+		Type:      targetType,
+		Active:    true,
+		Config:    config,
+	}
+
+	require.NoError(
+		t,
+		db.DB().Omit(clause.Associations).Create(tgt).Error,
+	)
+}
+
+// renderSourceDetailPage runs the real source detail handler
+// for a webhook and returns the rendered HTML.
+func renderSourceDetailPage(
+	t *testing.T,
+	h *handlers.Handlers,
+	sess *session.Session,
+	webhookID string,
+) string {
+	t.Helper()
+
+	req := httptest.NewRequestWithContext(
+		context.Background(),
+		http.MethodGet,
+		"/source/"+webhookID,
+		nil,
+	)
+
+	for _, c := range authenticatedCookies(
+		t, sess, deleteTestUserID, deleteTestUsername,
+	) {
+		req.AddCookie(c)
+	}
+
+	rctx := chi.NewRouteContext()
+	rctx.URLParams.Add(paramSourceID, webhookID)
+
+	req = req.WithContext(
+		context.WithValue(
+			req.Context(), chi.RouteCtxKey, rctx,
+		),
+	)
+
+	w := httptest.NewRecorder()
+	h.HandleSourceDetail().ServeHTTP(w, req)
+
+	require.Equal(t, http.StatusOK, w.Code)
+
+	return w.Body.String()
+}
+
+// TestHandleSourceDetail_MasksSlackWebhookURL is the
+// load-bearing regression test for the credential leak: the
+// rendered page must show the Slack target without any of the
+// secret path segments of its webhook URL.
+func TestHandleSourceDetail_MasksSlackWebhookURL(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h    *handlers.Handlers
+		sess *session.Session
+		db   *database.Database
+	)
+
+	app := newTestApp(t, &h, &sess, &db)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+	seedConfiguredTarget(
+		t, db, wh.ID,
+		database.TargetTypeSlack,
+		`{"webhookUrl":"`+slackWebhookURL+`"}`,
+	)
+
+	body := renderSourceDetailPage(t, h, sess, wh.ID)
+
+	assert.NotContains(t, body, slackSecretPath)
+	assert.NotContains(t, body, "T00000000")
+	assert.NotContains(t, body, "B00000000")
+	assert.NotContains(
+		t, body, "XXXXXXXXXXXXXXXXXXXXXXXX",
+	)
+	assert.NotContains(t, body, "webhookUrl")
+
+	assert.Contains(t, body, "Webhook URL")
+	assert.Contains(t, body, "https://hooks.slack.com/...")
+}
+
+// TestHandleSourceDetail_RendersNamedTargetFields proves the
+// other target types render labelled fields rather than the
+// stored blob.
+func TestHandleSourceDetail_RendersNamedTargetFields(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	var (
+		h    *handlers.Handlers
+		sess *session.Session
+		db   *database.Database
+	)
+
+	app := newTestApp(t, &h, &sess, &db)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+
+	seedConfiguredTarget(
+		t, db, wh.ID,
+		database.TargetTypeHTTP,
+		`{"url":"https://example.com/hook","timeout":30,`+
+			`"headers":{"Authorization":"Bearer sekrit"}}`,
+	)
+	seedConfiguredTarget(
+		t, db, wh.ID,
+		database.TargetTypeDatabase,
+		`{"expiry":"720h"}`,
+	)
+	seedConfiguredTarget(
+		t, db, wh.ID,
+		database.TargetType("carrier-pigeon"),
+		`{"beak":"sharp"}`,
+	)
+
+	body := renderSourceDetailPage(t, h, sess, wh.ID)
+
+	assert.Contains(t, body, "Destination URL")
+	assert.Contains(t, body, "https://example.com/hook")
+	assert.Contains(t, body, "Timeout")
+	assert.Contains(t, body, "1 configured")
+	assert.NotContains(t, body, "sekrit")
+
+	assert.Contains(t, body, "Archive Expiry")
+	assert.Contains(t, body, "720h")
+
+	// An unknown type gets the neutral placeholder, never the
+	// stored blob.
+	assert.Contains(t, body, "(unavailable)")
+	assert.NotContains(t, body, "beak")
+}