refactor: 改进音乐API代理的重定向和URL请求处理

- 新增对 type=url 请求的特殊处理逻辑
- 解析JSON响应中的url字段并自动跟随
- 提取 buildHeaders() 函数统一请求头构建
- 新增 requestStream() 函数处理流式请求和重定向
- 限制最大重定向次数为5次
- 改进 Range 和 If-Range 头部传递

sync-server/server.js

@@ -311,20 +311,132 @@ function downloadFile(url, dest) {
 // --- Music API Proxy Function ---
 function proxyRequest(targetUrl, req, res) {
     const parsedTarget = url.parse(targetUrl, true);
-    const isPicRequest = parsedTarget.query && parsedTarget.query.type === 'pic';
+    const requestType = parsedTarget.query && parsedTarget.query.type;
+    const isPicRequest = requestType === 'pic';
+    const isUrlRequest = requestType === 'url';
+    const maxRedirects = 5;
+
+    const buildHeaders = () => {
+        const headers = {
+            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
+            'Accept': '*/*',
+            'Accept-Encoding': 'identity'
+        };
+        if (req.headers.range) headers['Range'] = req.headers.range;
+        if (req.headers['if-range']) headers['If-Range'] = req.headers['if-range'];
+        return headers;
+    };
+
+    const requestStream = (nextUrl, redirectCount = 0) => {
+        if (redirectCount > maxRedirects) {
+            res.writeHead(502, { 'Content-Type': 'application/json' });
+            res.end(JSON.stringify({ error: 'Too many redirects' }));
+            return;
+        }
+
+        const parsedNext = url.parse(nextUrl);
+        const isHttps = parsedNext.protocol === 'https:';
+        const requestModule = isHttps ? https : http;
+        const options = {
+            hostname: parsedNext.hostname,
+            port: parsedNext.port || (isHttps ? 443 : 80),
+            path: parsedNext.path,
+            method: req.method,
+            headers: buildHeaders()
+        };
+
+        const proxyReq = requestModule.request(options, (proxyRes) => {
+            if (proxyRes.statusCode >= 300 && proxyRes.statusCode < 400 && proxyRes.headers.location) {
+                const resolved = url.resolve(nextUrl, proxyRes.headers.location);
+                proxyRes.resume();
+                requestStream(resolved, redirectCount + 1);
+                return;
+            }
+
+            const headers = { ...proxyRes.headers };
+            delete headers['content-encoding'];
+            delete headers['transfer-encoding'];
+            res.writeHead(proxyRes.statusCode || 200, headers);
+            proxyRes.pipe(res);
+        });
+
+        proxyReq.on('error', (e) => {
+            console.error('[Proxy] Stream error:', e.message);
+            res.writeHead(502, { 'Content-Type': 'application/json' });
+            res.end(JSON.stringify({ error: 'Proxy stream failed', message: e.message }));
+        });
+
+        if (req.method === 'POST') {
+            req.pipe(proxyReq);
+        } else {
+            proxyReq.end();
+        }
+    };
     
     const options = {
         hostname: parsedTarget.hostname,
         port: 443,
         path: parsedTarget.path,
         method: req.method,
-        headers: {
-            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
-            'Accept': '*/*',
-            'Accept-Encoding': 'identity'
-        }
+        headers: buildHeaders()
     };
 
+    if (isUrlRequest) {
+        const proxyReq = https.request(options, (proxyRes) => {
+            if (proxyRes.statusCode >= 300 && proxyRes.statusCode < 400 && proxyRes.headers.location) {
+                const resolved = url.resolve(targetUrl, proxyRes.headers.location);
+                proxyRes.resume();
+                requestStream(resolved, 1);
+                return;
+            }
+
+            const contentType = proxyRes.headers['content-type'] || '';
+            const shouldInspectBody = contentType.includes('application/json') || contentType.startsWith('text/');
+
+            if (shouldInspectBody) {
+                let body = '';
+                proxyRes.setEncoding('utf8');
+                proxyRes.on('data', chunk => body += chunk);
+                proxyRes.on('end', () => {
+                    try {
+                        const parsedBody = JSON.parse(body);
+                        if (parsedBody && parsedBody.url) {
+                            requestStream(parsedBody.url, 1);
+                            return;
+                        }
+                    } catch (e) {
+                        // fall through to return original body
+                    }
+
+                    res.writeHead(proxyRes.statusCode || 200, {
+                        'Content-Type': proxyRes.headers['content-type'] || 'application/json'
+                    });
+                    res.end(body);
+                });
+                return;
+            }
+
+            const headers = { ...proxyRes.headers };
+            delete headers['content-encoding'];
+            delete headers['transfer-encoding'];
+            res.writeHead(proxyRes.statusCode || 200, headers);
+            proxyRes.pipe(res);
+        });
+
+        proxyReq.on('error', (e) => {
+            console.error('[Proxy] Request error:', e.message);
+            res.writeHead(502, { 'Content-Type': 'application/json' });
+            res.end(JSON.stringify({ error: 'Proxy request failed', message: e.message }));
+        });
+
+        if (req.method === 'POST') {
+            req.pipe(proxyReq);
+        } else {
+            proxyReq.end();
+        }
+        return;
+    }
+
     const proxyReq = https.request(options, (proxyRes) => {
         const passThrough = () => {
             const headers = { ...proxyRes.headers };