feat(core): regex engine config (#10013)

docs/en/install/README.md

@@ -557,6 +557,8 @@ Configs in this sections are in beta stage, and are turn off by default. Please
 
 `ALLOW_USER_HOTLINK_TEMPLATE`: [Parameters->Multimedia processing](/en/parameter.html#multimedia-processing)
 
+`FILTER_REGEX_ENGINE`: Define Regex engine used in [Parameters->filtering](/en/parameter.html#filtering). Valid value are `[re, regexp]`. Default value is `re`. We suggest public instance should leave this value to default, and this option right now is mainly for backward compatibility.
+
 ### Other Application Configurations
 
 `DISALLOW_ROBOT`: prevent indexing by search engine, default to enable, set false or 0 to disable

docs/en/parameter.md

@@ -26,6 +26,16 @@ Please make sure you've [fully URL-encoded](https://gchq.github.io/CyberChef/#re
 
 :::
 
+::: warning Warning
+
+filter supports Regex, and due to the fact that some Regex are vulnerable to DoS (ReDoS), default engine `re` blocks some of these functionalities available in node `Regexp`. These two engines also behaves a bit different in some corner cases. [Details](https://github.com/uhop/node-re2#limitations-things-re2-does-not-support)
+
+
+If you need to use a different engine, please refer to [Deploy->Features->FILTER_REGEX_ENGINE](/en/install/#configuration-features).
+
+:::
+
+
 The following URL query parameters are supported, Regex support is built-in.
 
 Set `filter` to include the content
@@ -102,7 +112,7 @@ E.g. <https://rsshub.app/dcard/posts/popular?opencc=t2s>
 
 ## Multimedia processing
 
-::: warning 注意
+::: warning Warning
 
 This is an experimental API
 

docs/install/README.md

@@ -563,6 +563,8 @@ RSSHub 支持使用访问密钥 / 码，白名单和黑名单三种方式进行
 
 `ALLOW_USER_HOTLINK_TEMPLATE`: [通用参数 -> 多媒体处理](/parameter.html#duo-mei-ti-chu-li)特性控制
 
+`FILTER_REGEX_ENGINE`: 控制 [通用参数 -> 内容过滤](/parameter.html#nei-rong-guo-lu) 使用的正则引擎。可选`[re, regexp]`，默认`re`。我们推荐公开实例不要调整这个选项，这个选项目前主要用于向后兼容。
+
 ### 其他应用配置
 
 `DISALLOW_ROBOT`: 阻止搜索引擎收录，默认开启，设置 false 或 0 关闭

docs/parameter.md

@@ -26,6 +26,14 @@
 
 :::
 
+::: warning 注意
+
+filter 支持正则表达式。由于正则部分特性可被利用于 DoS (ReDOS)，默认引擎`RE`屏蔽了部分`Regexp`功能，且在部分情况下表现不一致。具体差异可以[查看文档](https://github.com/uhop/node-re2#limitations-things-re2-does-not-support)
+
+如果需要指定不同的引擎，请参考[功能特性 -> FILTER_REGEX_ENGINE](install/#pei-zhi-gong-neng-te-xing)。
+
+:::
+
 可以使用以下 URL query 过滤内容，支持通过正则表达式过滤
 
 `filter` 选出想要的内容

lib/config.js

@@ -93,6 +93,7 @@ const calculateValue = () => {
         },
         feature: {
             allow_user_hotlink_template: envs.ALLOW_USER_HOTLINK_TEMPLATE === 'true',
+            filter_regex_engine: envs.FILTER_REGEX_ENGINE || 're',
         },
         suffix: envs.SUFFIX,
         titleLengthLimit: parseInt(envs.TITLE_LENGTH_LIMIT) || 150,

lib/middleware/parameter.js

@@ -152,10 +152,25 @@ module.exports = async (ctx, next) => {
             // filter
             const makeRegex = (string) => {
                 // default: case_senstivie = true
+                const engine = config.feature.filter_regex_engine;
                 if (ctx.query.filter_case_sensitive === 'false') {
-                    return new RE2(string, 'i');
+                    switch (engine) {
+                        case 'regexp':
+                            return new RegExp(string, 'i');
+                        case 're':
+                            return new RE2(string, 'i');
+                        default:
+                            throw Error(`Invalid Engine Value: ${engine}, please check your config.`);
+                    }
                 } else {
-                    return new RE2(string);
+                    switch (engine) {
+                        case 'regexp':
+                            return new RegExp(string);
+                        case 're':
+                            return new RE2(string);
+                        default:
+                            throw Error(`Invalid Engine Value: ${engine}, please check your config.`);
+                    }
                 }
             };