Support for specifying getRedirectedUrl

README.md

@@ -76,7 +76,8 @@ new Purlfy({
         redirected: Number, // Number of URLs redirected (`redirect` mode)
         char: Number, // Number of characters deleted
     },
-    log: Function, // Log function (default: `console.log.bind(console, "\x1b[38;2;220;20;60m[pURLfy]\x1b[0m")`)
+    log: Function, // Log function (default is using `console.log` for output)
+    getRedirectedUrl: async Function, // Function to get redirected URL (default is using `fetch` for `HEAD` request, refer to [redirect mode](#-redirect-mode-redirect) for more details)
 })
 ```
 
@@ -287,16 +288,12 @@ If you'd like to learn more about the syntax of the "replacement string", please
 | --- | --- | --- |
 | `continue` | `Boolean` | `true` |
 
-Under Redirect mode, pURLfy will:
-
-1. Attempt to fire a `HEAD` request to the matched URL.
-2. If the status code is `3xx`, the `Location` header will be used as the new URL.
-3. If `continue` is not set to `false`, purify the new URL again.
+Under Redirect mode, pURLfy will call passed-in parameter `getRedirectedUrl` to get the redirected URL. The `getRedirectedUrl` should be an async function, accept a single `string` parameter `url`, and return a new `string` representing the redirected URL. The default implementation is to fire a `HEAD` request to the matched URL and return the `Location` header. If `continue` is not set to `false`, the new URL will be purified again.
 
 #### 🔵 Lambda Mode `lambda`
 
 > [!CAUTION]
-> For security reasons, the `lambda` mode is disabled by default. Refer to the [API documentation](#-API) for enabling it.
+> For security reasons, the `lambda` mode is disabled by default. If you **trust the rules provider**, refer to the [API documentation](#-API) for enabling it.
 
 | Param | Type | Default |
 | --- | --- | --- |

README_zh.md

@@ -76,7 +76,8 @@ new Purlfy({
         redirected: Number, // 重定向的网址数量 (`redirect` 模式)
         char: Number, // 移除的字符数量
     },
-    log: Function, // 日志函数 (默认: `console.log.bind(console, "\x1b[38;2;220;20;60m[pURLfy]\x1b[0m")`)
+    log: Function, // 日志函数 (默认通过 `console.log` 输出)
+    getRedirectedUrl: async Function, // 获取重定向后的 URL 的函数 (默认使用 `fetch` 发送 `HEAD` 请求，详见 [重定向模式](#-重定向模式-redirect))
 })
 ```
 
@@ -281,22 +282,18 @@ new Purlfy({
 #### 🟡 重定向模式 `redirect`
 
 > [!CAUTION]
-> 出于兼容性考虑，此模式默认禁用。若您想要启用此模式并且 **执行环境支持跨域**，请参照 [API 文档](#-API) 开启此模式。
+> 出于兼容性考虑，此模式默认禁用。请参照 [API 文档](#-API) 开启此模式。
 
 | 参数 | 类型 | 默认值 |
 | --- | --- | --- |
 | `continue` | `Boolean` | `true` |
 
-重定向模式下，pURLfy 会:
-
-1. 向匹配到的网址发起 `HEAD` 请求
-2. 若返回的状态码为 `3xx`，则会将头部信息中的 `Location` 作为新的 URL
-3. 若 `continue` 未被设置为 `false`，则再次净化新的 URL
+重定向模式下，pURLfy 会调用传入参数 `getRedirectedUrl` 来获取重定向后的 URL。`getRedirectedUrl` 应为一个异步函数，接受一个类型为 `string` 的参数 `url`，并返回一个新的 `string` 类型的 URL 作为重定向后的 URL。默认情况下，pURLfy 会使用 `fetch` 发送 `HEAD` 请求来获取重定向后的 URL。若 `continue` 未被设置为 `false`，则再次净化新的 URL。
 
 #### 🔵 匿名函数模式 `lambda`
 
 > [!CAUTION]
-> 出于安全考虑，此模式默认禁用。若您想要启用此模式并且 **信任规则来源**，请参照 [API 文档](#-API) 开启此模式。
+> 出于安全考虑，此模式默认禁用。若您 **信任规则来源**，请参照 [API 文档](#-API) 开启此模式。
 
 | 参数 | 类型 | 默认值 |
 | --- | --- | --- |

purlfy.js

@@ -3,6 +3,17 @@ class Purlfy extends EventTarget {
     lambdaEnabled = false;
     maxIterations = 5;
     #log = console.log.bind(console, "\x1b[38;2;220;20;60m[pURLfy]\x1b[0m");
+    #getRedirectedUrl = async url => {
+        const r = await fetch(url, {
+            method: "HEAD",
+            redirect: "manual"
+        });
+        if ((r.status === 301 || r.status === 302) && r.headers.has("location")) {
+            const dest = r.headers.get("location");
+            return dest;
+        }
+        return null;
+    };
     #paramDecoders = {
         "url": decodeURIComponent,
         "base64": s => decodeURIComponent(escape(atob(s.replaceAll('_', '/').replaceAll('-', '+')))),
@@ -26,6 +37,7 @@ class Purlfy extends EventTarget {
         this.maxIterations = options?.maxIterations ?? this.maxIterations;
         Object.assign(this.#statistics, options?.statistics);
         this.#log = options?.log ?? this.#log;
+        this.#getRedirectedUrl = options?.getRedirectedUrl ?? this.#getRedirectedUrl;
     }
 
     clearStatistics() {
@@ -203,21 +215,19 @@ class Purlfy extends EventTarget {
                     logFunc("Redirect mode is disabled.");
                     break;
                 }
-                let r = null;
+                let dest = null;
                 try {
-                    r = await fetch(urlObj.href, {
-                        method: "HEAD",
-                        redirect: "manual"
-                    });
+                    dest = await this.#getRedirectedUrl(urlObj.href);
                 } catch (e) {
-                    logFunc("Error fetching URL:", e);
+                    logFunc("Error following redirect:", e);
                     break;
                 }
-                if ((r.status === 301 || r.status === 302) && r.headers.has("location")) {
-                    let dest = r.headers.get("location");
-                    urlObj = new URL(dest);
+                if (dest && URL.canParse(dest, urlObj.href)) {
+                    urlObj = new URL(dest, urlObj.href);
                     shallContinue = rule.continue ?? true;
                     increment.redirected++;
+                } else {
+                    logFunc("Invalid redirect destination:", dest);
                 }
                 break;
             }