rudimentary "spam filter"

app/Http/Middleware/GuestbookValidate.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class GuestbookValidate
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        if (
+            !$request->validate([
+                'name' => 'required',
+                'message' => 'required'
+            ]) ||
+            $this->containsUrl($request->get('message')) ||
+            $this->containsUrl($request->get('name'))
+        ) {
+            return response()->view('errors.guestbook-invalid', [], 400);
+        }
+        return $next($request);
+    }
+
+    public function containsUrl($str) {
+        $matches = [];
+        $pattern = '/\b(?:https?|ftp|www)(:\/\/)*[-A-Z0-9+&@#\/%?=~_|$!:,.;]*[A-Z0-9+&@#\/%=~_|$]/i';
+        preg_match_all($pattern, $str, $matches);
+        return count($matches[0]);
+    }
+}