perf: 重构敏感词过滤为DFA算法，并引入WebSocket房间频道鉴权Redis缓存

app/Services/MessageFilterService.php

@@ -20,6 +20,35 @@ class MessageFilterService
         '外挂', '刷单', '脚本', // 示例黑名单
     ];
 
+    /**
+     * Trie 字典树实例，用于 DFA 过滤
+     */
+    private ?array $trie = null;
+
+    /**
+     * 构建 Trie 字典树
+     */
+    private function buildTrie(): void
+    {
+        if ($this->trie !== null) {
+            return;
+        }
+
+        $this->trie = [];
+        foreach ($this->badWords as $word) {
+            $temp = &$this->trie;
+            $len = mb_strlen($word);
+            for ($i = 0; $i < $len; $i++) {
+                $char = mb_substr($word, $i, 1);
+                if (! isset($temp[$char])) {
+                    $temp[$char] = [];
+                }
+                $temp = &$temp[$char];
+            }
+            $temp['is_end'] = true;
+        }
+    }
+
     /**
      * 执行过滤净化，保障入库和显示安全。
      *
@@ -35,16 +64,46 @@ class MessageFilterService
         // 1. HTML 标签全量脱除，阻绝任意 XSS/HTML 注入
         $content = strip_tags($content);
 
-        // 2. 敏感词替换
-        foreach ($this->badWords as $word) {
-            if (mb_strpos($content, $word) !== false) {
-                // 将脏字替换为相同长度的 星号 或 提示
-                $replacement = str_repeat('*', mb_strlen($word));
-                $content = str_replace($word, $replacement, $content);
+        // 2. 惰性初始化并构建 DFA 字典树
+        $this->buildTrie();
+
+        // 3. 将字符串转为多字节字符数组，进行 DFA 扫描与替换
+        $len = mb_strlen($content);
+        $chars = [];
+        for ($i = 0; $i < $len; $i++) {
+            $chars[] = mb_substr($content, $i, 1);
+        }
+
+        $result = [];
+        $i = 0;
+        while ($i < $len) {
+            $temp = &$this->trie;
+            $matchLength = 0;
+            $j = $i;
+
+            while ($j < $len && isset($temp[$chars[$j]])) {
+                $temp = &$temp[$chars[$j]];
+                if (isset($temp['is_end']) && $temp['is_end'] === true) {
+                    $matchLength = $j - $i + 1; // 匹配到最长敏感词
+                }
+                $j++;
+            }
+
+            if ($matchLength > 0) {
+                // 替换为相同长度的 *
+                for ($k = 0; $k < $matchLength; $k++) {
+                    $result[] = '*';
+                }
+                $i += $matchLength; // 跳过敏感词
+            } else {
+                $result[] = $chars[$i];
+                $i++;
             }
         }
 
-        // 3. 将连续的空格去重，只保留一个真正的空格
+        $content = implode('', $result);
+
+        // 4. 将连续的空格去重，只保留一个真正的空格
         $content = preg_replace('/\s+/', ' ', $content);
 
         return trim($content);