Disable problem creation when not logged in

modules/problem.js

@@ -84,6 +84,7 @@ app.get('/problem/:id/edit', async (req, res) => {
     let problem = await Problem.fromID(id);
 
     if (!problem) {
+      if (!res.locals.user) throw 'Permission denied.';
       problem = await Problem.create();
       problem.id = id;
       problem.allowedEdit = true;

views/problems.ejs

@@ -1,13 +1,15 @@
 <% this.title = '题库' %>
 <% include header %>
 <div class="padding">
-  <div class="ui grid">
-    <div class="row">
-      <div class="column">
-        <a href="<%= syzoj.utils.makeUrl(['problem', 0, 'edit']) %>" class="ui mini right floated button">添加题目</a>
+  <% if (user) { %>
+    <div class="ui grid">
+      <div class="row">
+        <div class="column">
+          <a href="<%= syzoj.utils.makeUrl(['problem', 0, 'edit']) %>" class="ui mini right floated button">添加题目</a>
+        </div>
       </div>
     </div>
-  </div>
+  <% } %>
   <table class="ui very basic center aligned table">
     <thead>
       <tr>