pllx
112 lines
2.9 KiB
PHP
112 lines
2.9 KiB
PHP
<?php
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/**
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* 文件功能：聊天内容过滤器 (敏感词与 HTML 净化)
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* 替代旧版 ASP中的 TrStr() / SHTM() 等各种过滤函数。
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*
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* @author ChatRoom Laravel
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*
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* @version 1.0.0
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*/
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namespace App\Services;
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class MessageFilterService
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{
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/**
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* 简单的关键词黑名单，未来可放到数据库或 Redis 动态加载
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*/
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private array $badWords = [
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'外挂', '刷单', '脚本', // 示例黑名单
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];
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/**
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* Trie 字典树实例，用于 DFA 过滤
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*/
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private ?array $trie = null;
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/**
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* 构建 Trie 字典树
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*/
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private function buildTrie(): void
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{
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if ($this->trie !== null) {
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return;
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}
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$this->trie = [];
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foreach ($this->badWords as $word) {
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$temp = &$this->trie;
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$len = mb_strlen($word);
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for ($i = 0; $i < $len; $i++) {
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$char = mb_substr($word, $i, 1);
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if (! isset($temp[$char])) {
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$temp[$char] = [];
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}
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$temp = &$temp[$char];
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}
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$temp['is_end'] = true;
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}
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}
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/**
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* 执行过滤净化，保障入库和显示安全。
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*
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* @param string $content 原始用户发送内容
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* @return string 净化后的内容
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*/
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public function filter(string $content): string
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{
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if ($content === '') {
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return '';
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}
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// 1. HTML 标签全量脱除，阻绝任意 XSS/HTML 注入
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$content = strip_tags($content);
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// 2. 惰性初始化并构建 DFA 字典树
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$this->buildTrie();
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// 3. 将字符串转为多字节字符数组，进行 DFA 扫描与替换
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$len = mb_strlen($content);
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$chars = [];
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for ($i = 0; $i < $len; $i++) {
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$chars[] = mb_substr($content, $i, 1);
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}
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$result = [];
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$i = 0;
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while ($i < $len) {
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$temp = &$this->trie;
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$matchLength = 0;
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$j = $i;
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while ($j < $len && isset($temp[$chars[$j]])) {
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$temp = &$temp[$chars[$j]];
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if (isset($temp['is_end']) && $temp['is_end'] === true) {
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$matchLength = $j - $i + 1; // 匹配到最长敏感词
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}
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$j++;
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}
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if ($matchLength > 0) {
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// 替换为相同长度的 *
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for ($k = 0; $k < $matchLength; $k++) {
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$result[] = '*';
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}
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$i += $matchLength; // 跳过敏感词
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} else {
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$result[] = $chars[$i];
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$i++;
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}
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}
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$content = implode('', $result);
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// 4. 将连续的空格去重，只保留一个真正的空格
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$content = preg_replace('/\s+/', ' ', $content);
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return trim($content);
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}
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}
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