Add upload security: size limit, per-user and site-wide post caps

Reject base64 payloads over 10 MB, limit users to 50 posts each,
and cap total posts at 10,000 (~650 MB on disk). Document upload
security model in README.

1 files changed, 28 insertions, 0 deletions

diff --git a/src/app/Controllers/EditorController.php b/src/app/Controllers/EditorController.php
index c7dd9fc..c8cae0d 100644
--- a/src/app/Controllers/EditorController.php
+++ b/src/app/Controllers/EditorController.php
@@ -12,6 +12,13 @@ use App\Models\Post;
 
 class EditorController
 {
+    // Per-user and site-wide caps prevent disk exhaustion — even if someone
+    // creates multiple accounts, the total limit still applies.
+    // Each composited image is a 640×640 JPEG at quality 85, averaging ~65 KB.
+    // 50 posts/user ≈ 3.2 MB per user, 10 000 total ≈ 650 MB on disk.
+    private const MAX_POSTS_PER_USER = 50;
+    private const MAX_POSTS_TOTAL = 10000;
+
     private Post $post;
 
     public function __construct()
@@ -60,7 +67,28 @@ class EditorController
             return;
         }
 
+        if ($this->post->countByUserId($_SESSION['user_id']) >= self::MAX_POSTS_PER_USER) {
+            http_response_code(400);
+            echo json_encode(['error' => 'You have reached the maximum number of posts.']);
+            return;
+        }
+
+        if ($this->post->countAll() >= self::MAX_POSTS_TOTAL) {
+            http_response_code(400);
+            echo json_encode(['error' => 'The site has reached its storage limit.']);
+            return;
+        }
+
         $imageData = $input['image_data'] ?? '';
+
+        // Reject oversized payloads before doing any processing — base64 adds ~33%
+        // overhead, so 10 MB base64 ≈ 7.5 MB image, which is more than enough
+        if (\strlen($imageData) > 10 * 1024 * 1024) {
+            http_response_code(400);
+            echo json_encode(['error' => 'Image too large.']);
+            return;
+        }
+
         $overlayName = $input['overlay'] ?? '';
         $overlayScale = (float) ($input['overlay_scale'] ?? 1.0);