import { parseURL } from "./urlParser.js";
import { isValidHostName } from "./utils.js";
import { withCORS } from "./cors.js";
import { onRequestStart, onRequestEnd, onError, renderPrometheus } from "./metrics.js";
/**
* 创建代理处理器
* @param {object} options
* @param {import('http-proxy').default} proxy
* @returns {(req, res) => void}
*/
export function createProxyHandler(options, proxy) {
const {
originBlacklist = [],
originWhitelist = [],
requireHeader = [],
removeHeaders = [],
setHeaders = {},
checkRateLimit = null,
redirectSameOrigin = false,
} = options || {};
// 根路径文档页渲染（KISS/YAGNI：仅提供必要说明）
const renderLandingHTML = (req) => {
const host = req.headers.host || `localhost:${process.env.PORT || 4399}`;
const base = `http://${host}`;
return `\n\n\n \n \n CORS Proxy 服务\n \n\n\n CORS Proxy Server
\n 通过在目标 URL 前加上代理前缀来解决跨域。
\n 用法
\n ${base}/<目标URL>
\n 示例
\n GET ${base}/https://api.github.com/users/octocat\nGET ${base}/https://jsonplaceholder.typicode.com/posts/1
\n 说明
\n \n - 支持
GET/POST/PUT/DELETE 等常见方法。 \n - 自动添加 CORS 响应头。
\n - 可设置
PORT 环境变量修改端口（默认 4399）。 \n
\n 将真实 API 地址拼接在 ${base}/ 后即可。
\n\n`;
};
return (req, res) => {
const start = Date.now();
const reqId = Math.random().toString(36).slice(2, 10);
onRequestStart();
const log = (level, data) => {
try {
console.log(JSON.stringify({ level, reqId, method: req.method, path: req.url, origin: req.headers.origin || null, ...data }));
} catch {}
};
// 健康检查与指标
if (req.url === "/healthz") {
const headers = withCORS({ "Content-Type": "application/json" }, req);
res.writeHead(200, headers);
res.end(JSON.stringify({ status: "ok", uptime: process.uptime() }));
onRequestEnd();
return;
}
if (req.url === "/metrics") {
const text = renderPrometheus();
res.writeHead(200, { "Content-Type": "text/plain; version=0.0.4" });
res.end(text);
onRequestEnd();
return;
}
// 0. 处理 OPTIONS 预检请求
if (req.method === "OPTIONS") {
const headers = withCORS({}, req);
res.writeHead(200, headers);
res.end();
return;
}
// 0.1 检查来源黑/白名单
const origin = req.headers.origin || "";
if (originBlacklist.length && originBlacklist.includes(origin)) {
onError();
res.writeHead(403, withCORS({ "Content-Type": "application/json" }, req));
res.end(JSON.stringify({ error: "origin_blacklisted" }));
onRequestEnd();
return;
}
if (originWhitelist.length && !originWhitelist.includes(origin)) {
onError();
res.writeHead(403, withCORS({ "Content-Type": "application/json" }, req));
res.end(JSON.stringify({ error: "origin_not_whitelisted" }));
onRequestEnd();
return;
}
// 0.2 检查必需头部
if (
requireHeader.length &&
!requireHeader.every((h) => req.headers[h.toLowerCase()])
) {
onError();
res.writeHead(400, withCORS({ "Content-Type": "application/json" }, req));
res.end(JSON.stringify({ error: "missing_required_header" }));
onRequestEnd();
return;
}
// 0.3 检查限流
if (typeof checkRateLimit === "function" && !checkRateLimit(req)) {
onError();
res.writeHead(429, withCORS({ "Content-Type": "application/json" }, req));
res.end(JSON.stringify({ error: "rate_limit_exceeded" }));
onRequestEnd();
return;
}
// 1. 提取目标 URL
const url = decodeURIComponent(req.url.substring(1));
if (!url || req.url === "/") {
const headers = withCORS({ "Content-Type": "text/html; charset=utf-8" }, req);
res.writeHead(200, headers);
res.end(renderLandingHTML(req));
onRequestEnd();
return;
}
const targetLocation = parseURL(url);
if (!targetLocation) {
onError();
res.writeHead(400, withCORS({ "Content-Type": "application/json" }, req));
res.end(JSON.stringify({ error: "invalid_target_url" }));
onRequestEnd();
return;
}
// 2. 主机名校验
if (!isValidHostName(targetLocation.hostname)) {
onError();
res.writeHead(404, withCORS({ "Content-Type": "application/json" }, req));
res.end(JSON.stringify({ error: "invalid_host" }));
onRequestEnd();
return;
}
// 2.1 移除指定头部
removeHeaders.forEach((h) => {
delete req.headers[h.toLowerCase()];
});
// 2.2 设置指定头部
Object.entries(setHeaders).forEach(([k, v]) => {
req.headers[k.toLowerCase()] = v;
});
// 3. 代理请求
proxy.once("proxyRes", (proxyRes, req2, res2) => {
// 处理重定向
if ([301, 302, 303, 307, 308].includes(proxyRes.statusCode)) {
const loc = proxyRes.headers["location"];
if (loc) {
const newUrl = new URL(loc, targetLocation);
// redirectSameOrigin: 只重定向同源
if (!redirectSameOrigin || newUrl.origin === targetLocation.origin) {
proxyRes.headers["location"] = "/" + newUrl.href;
}
}
}
// 添加 CORS 头
Object.entries(withCORS({}, req2)).forEach(([k, v]) => {
res2.setHeader(k, v);
});
// 记录成功日志
try { console.log(JSON.stringify({ level: "info", reqId, status: proxyRes.statusCode, target: targetLocation.href, duration_ms: Date.now() - start })); } catch {}
});
proxy.web(req, res, {
target: targetLocation.href,
ignorePath: true,
changeOrigin: true,
});
res.on("close", () => {
onRequestEnd();
});
};
}
// 基础可靠性：socket 超时（15s 默认）
try {
req.socket.setTimeout(15000, () => {
onError();
try {
res.writeHead(504, withCORS({ "Content-Type": "application/json" }, req));
res.end(JSON.stringify({ error: "client_timeout" }));
} catch {}
try { req.destroy(); } catch {}
onRequestEnd();
});
} catch {}