Search: Set limits on the amount of search terms

Sets some reasonable limits, which are higher when logged in since that
infers a little extra trust.
Helps prevent against large resource consuption attacks via super heavy
search queries.

Thanks to Gabriel Rodrigues AKA TEXUGO for reporting.

Author: ssddanbrown

app/Search/SearchController.php

@@ -78,8 +78,9 @@ public function searchForSelector(Request $request, QueryPopular $queryPopular)
 
         // Search for entities otherwise show most popular
         if ($searchTerm !== false) {
-            $searchTerm .= ' {type:' . implode('|', $entityTypes) . '}';
-            $entities = $this->searchRunner->searchEntities(SearchOptions::fromString($searchTerm), 'all', 1, 20)['results'];
+            $options = SearchOptions::fromString($searchTerm);
+            $options->setFilter('type', implode('|', $entityTypes));
+            $entities = $this->searchRunner->searchEntities($options, 'all', 1, 20)['results'];
         } else {
             $entities = $queryPopular->run(20, 0, $entityTypes);
         }

app/Search/SearchOptionSet.php

@@ -82,4 +82,12 @@ public function nonNegated(): self
         $values = array_values(array_filter($this->options, fn (SearchOption $option) => !$option->negated));
         return new self($values);
     }
+
+    /**
+     * @return self<T>
+     */
+    public function limit(int $limit): self
+    {
+        return new self(array_slice(array_values($this->options), 0, $limit));
+    }
 }

app/Search/SearchOptions.php

@@ -35,6 +35,7 @@ public static function fromString(string $search): self
     {
         $instance = new self();
         $instance->addOptionsFromString($search);
+        $instance->limitOptions();
         return $instance;
     }
 
@@ -87,6 +88,8 @@ public static function fromRequest(Request $request): self
             $instance->filters = $instance->filters->merge($extras->filters);
         }
 
+        $instance->limitOptions();
+
         return $instance;
     }
 
@@ -147,6 +150,25 @@ protected function addOptionsFromString(string $searchString): void
         $this->filters = $this->filters->merge(new SearchOptionSet($terms['filters']));
     }
 
+    /**
+     * Limit the amount of search options to reasonable levels.
+     * Provides higher limits to logged-in users since that signals a slightly
+     * higher level of trust.
+     */
+    protected function limitOptions(): void
+    {
+        $userLoggedIn = !user()->isGuest();
+        $searchLimit = $userLoggedIn ? 10 : 5;
+        $exactLimit = $userLoggedIn ? 4 : 2;
+        $tagLimit = $userLoggedIn ? 8 : 4;
+        $filterLimit = $userLoggedIn ? 10 : 5;
+
+        $this->searches = $this->searches->limit($searchLimit);
+        $this->exacts = $this->exacts->limit($exactLimit);
+        $this->tags = $this->tags->limit($tagLimit);
+        $this->filters = $this->filters->limit($filterLimit);
+    }
+
     /**
      * Decode backslash escaping within the input string.
      */

tests/Search/SearchOptionsTest.php

@@ -142,4 +142,53 @@ public function test_from_request_properly_parses_out_extras_as_string()
         $this->assertEquals('dino', $options->exacts->all()[0]->value);
         $this->assertTrue($options->exacts->all()[0]->negated);
     }
+
+    public function test_from_string_results_are_count_limited_and_larger_for_logged_in_users()
+    {
+        $terms = [
+            ...array_fill(0, 40, 'cat'),
+            ...array_fill(0, 50, '"bees"'),
+            ...array_fill(0, 50, '{is_template}'),
+            ...array_fill(0, 50, '[a=b]'),
+        ];
+
+        $options = SearchOptions::fromString(implode(' ', $terms));
+
+        $this->assertCount(5, $options->searches->all());
+        $this->assertCount(2, $options->exacts->all());
+        $this->assertCount(4, $options->tags->all());
+        $this->assertCount(5, $options->filters->all());
+
+        $this->asEditor();
+        $options = SearchOptions::fromString(implode(' ', $terms));
+
+        $this->assertCount(10, $options->searches->all());
+        $this->assertCount(4, $options->exacts->all());
+        $this->assertCount(8, $options->tags->all());
+        $this->assertCount(10, $options->filters->all());
+    }
+
+    public function test_from_request_results_are_count_limited_and_larger_for_logged_in_users()
+    {
+        $request = new Request([
+            'search' => str_repeat('hello ', 20),
+            'tags' => array_fill(0, 20, 'a=b'),
+            'extras' => str_repeat('-[b=c] -{viewed_by_me} -"dino"', 20),
+        ]);
+
+        $options = SearchOptions::fromRequest($request);
+
+        $this->assertCount(5, $options->searches->all());
+        $this->assertCount(2, $options->exacts->all());
+        $this->assertCount(4, $options->tags->all());
+        $this->assertCount(5, $options->filters->all());
+
+        $this->asEditor();
+        $options = SearchOptions::fromRequest($request);
+
+        $this->assertCount(10, $options->searches->all());
+        $this->assertCount(4, $options->exacts->all());
+        $this->assertCount(8, $options->tags->all());
+        $this->assertCount(10, $options->filters->all());
+    }
 }