Exports: Added rate limits for UI exports

Just as a measure to prevent potential abuse of these potentially
longer-running endpoints.
Adds test to cover for ZIP exports, but applied to all formats.

app/App/Providers/RouteServiceProvider.php

@@ -85,5 +85,12 @@ class RouteServiceProvider extends ServiceProvider
         RateLimiter::for('public', function (Request $request) {
             return Limit::perMinute(10)->by($request->ip());
         });
+
+        RateLimiter::for('exports', function (Request $request) {
+            $user = user();
+            $attempts = $user->isGuest() ? 4 : 10;
+            $key = $user->isGuest() ? $request->ip() : $user->id;
+            return Limit::perMinute($attempts)->by($key);
+        });
     }
 }

app/Exports/Controllers/BookExportController.php

@@ -16,6 +16,7 @@ class BookExportController extends Controller
         protected ExportFormatter $exportFormatter,
     ) {
         $this->middleware('can:content-export');
+        $this->middleware('throttle:exports');
     }
 
     /**

app/Exports/Controllers/ChapterExportController.php

@@ -16,6 +16,7 @@ class ChapterExportController extends Controller
         protected ExportFormatter $exportFormatter,
     ) {
         $this->middleware('can:content-export');
+        $this->middleware('throttle:exports');
     }
 
     /**

app/Exports/Controllers/PageExportController.php

@@ -17,6 +17,7 @@ class PageExportController extends Controller
         protected ExportFormatter $exportFormatter,
     ) {
         $this->middleware('can:content-export');
+        $this->middleware('throttle:exports');
     }
 
     /**

tests/Exports/ZipExportTest.php

@@ -423,6 +423,28 @@ class ZipExportTest extends TestCase
         $this->assertStringContainsString("[Link to chapter]([[bsexport:chapter:{$chapter->id}]])", $pageData['markdown']);
     }
 
+    public function test_exports_rate_limited_low_for_guest_viewers()
+    {
+        $this->setSettings(['app-public' => 'true']);
+
+        $page = $this->entities->page();
+        for ($i = 0; $i < 4; $i++) {
+            $this->get($page->getUrl("/export/zip"))->assertOk();
+        }
+        $this->get($page->getUrl("/export/zip"))->assertStatus(429);
+    }
+
+    public function test_exports_rate_limited_higher_for_logged_in_viewers()
+    {
+        $this->asAdmin();
+
+        $page = $this->entities->page();
+        for ($i = 0; $i < 10; $i++) {
+            $this->get($page->getUrl("/export/zip"))->assertOk();
+        }
+        $this->get($page->getUrl("/export/zip"))->assertStatus(429);
+    }
+
     protected function extractZipResponse(TestResponse $response): ZipResultData
     {
         $zipData = $response->streamedContent();