省钱秘笈之巧用Cloudflare免费做个镜像网站

偶然看到一个利用 Cloudflare Workers 做镜像的方法，无须购买服务器了，留作备用。
GitHub 项目：https://github.com/Siujoeng-Lau/Workers-Proxy

如果已经注册了 Cloudflare 账号，直接在左上 Products->Workers，没有就注册一个账号再说。
填写一个唯一子域名，Set up：
选择免费版：
点击 Create a Worker 创建一个 Worker：
自动生成一串名称，有 hello world 示例代码：

删除示例，拷贝下方代码，看预览，保存部署：

// 代理网站.
const upstream = 'www.google.com'

// 代理网站的目录.
const upstream_path = '/'

// 手机用户代理网站.
const upstream_mobile = 'www.google.com'

// 屏蔽国家和地区.
const blocked_region = ['KP', 'SY', 'PK', 'CU']

// 屏蔽 IP 地址.
const blocked_ip_address = ['0.0.0.0', '127.0.0.1']

// 源站是否开启 HTTPS.
const https = true

// 文本替换.
const replace_dict = {
    '$upstream': '$custom_domain',
    '//google.com': ''
}

addEventListener('fetch', event => {
    event.respondWith(fetchAndApply(event.request));
})

async function fetchAndApply(request) {

    const region = request.headers.get('cf-ipcountry').toUpperCase();
    const ip_address = request.headers.get('cf-connecting-ip');
    const user_agent = request.headers.get('user-agent');

    let response = null;
    let url = new URL(request.url);
    let url_hostname = url.hostname;

    if (https == true) {
        url.protocol = 'https:';
    } else {
        url.protocol = 'http:';
    }

    if (await device_status(user_agent)) {
        var upstream_domain = upstream;
    } else {
        var upstream_domain = upstream_mobile;
    }

    url.host = upstream_domain;
    if (url.pathname == '/') {
        url.pathname = upstream_path;
    } else {
        url.pathname = upstream_path + url.pathname;
    }

    if (blocked_region.includes(region)) {
        response = new Response('Access denied: WorkersProxy is not available in your region    yet.', {
            status: 403
        });
    } else if (blocked_ip_address.includes(ip_address)) {
        response = new Response('Access denied: Your IP address is blocked by WorkersProxy.',   {
            status: 403
        });
    } else {
        let method = request.method;
        let request_headers = request.headers;
        let new_request_headers = new Headers(request_headers);

        new_request_headers.set('Host', url.hostname);
        new_request_headers.set('Referer', url.hostname);

        let original_response = await fetch(url.href, {
            method: method,
            headers: new_request_headers
        })

        let original_response_clone = original_response.clone();
        let original_text = null;
        let response_headers = original_response.headers;
        let new_response_headers = new Headers(response_headers);
        let status = original_response.status;

        new_response_headers.set('access-control-allow-origin', '*');
        new_response_headers.set('access-control-allow-credentials', true);
        new_response_headers.delete('content-security-policy');
        new_response_headers.delete('content-security-policy-report-only');
        new_response_headers.delete('clear-site-data');

        const content_type = new_response_headers.get('content-type');
        if (content_type.includes('text/html') && content_type.includes('UTF-8')) {
            original_text = await replace_response_text(original_response_clone,    upstream_domain, url_hostname);
        } else {
            original_text = original_response_clone.body
        }

        response = new Response(original_text, {
            status,
            headers: new_response_headers
        })
    }
    return response;
}

async function replace_response_text(response, upstream_domain, host_name) {
    let text = await response.text()

    var i, j;
    for (i in replace_dict) {
        j = replace_dict[i]
        if (i == '$upstream') {
            i = upstream_domain
        } else if (i == '$custom_domain') {
            i = host_name
        }

        if (j == '$upstream') {
            j = upstream_domain
        } else if (j == '$custom_domain') {
            j = host_name
        }

        let re = new RegExp(i, 'g')
        text = text.replace(re, j);
    }
    return text;
}


async function device_status(user_agent_info) {
    var agents = ["Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod"];
    var flag = true;
    for (var v = 0; v < agents.length; v++) {
        if (user_agent_info.indexOf(agents[v]) > 0) {
            flag = false;
            break;
        }
    }
    return flag;
}

返回可重命名，这时就可以直接访问 WorkerName.Subdomain.workers.dev 了：
觉得域名太长不太好记，可以用自己的域名，前提是要在 cloudflare 解析，选择域名，点击 Workers->Add router：
Route 填 subdomain.yourdomain.com/* ，Worker 选择前面的部署：
在域名 DNS 解析里新建一个 CNAME 记录指向 WorkerName.Subdomain.workers.dev，等待生效后就可以用自己的域名访问了：
有时候会出现下面这个界面，等一会或者换个浏览器再看看：