使用Cloudflare创建镜像站

最近使用Unsplash的API，但是速度太慢了，简直受不了，本来打算搞一台国外服务器来中转，忽然发现可以利用Cloudflare的Worker来制作镜像站，Workers 每天有免费的 10 万次请求，个人使用绰绰有余了，还可以绑定自定义域名。

创建镜像站

首先登录cloudflare.com，进入控制台 - Works - 创建服务 - 选择HTTP处理程序

创建完成后，点击快速编辑

拷贝进下方的代码：

// 你要镜像的网站.
const upstream = 'www.google.com'
// 镜像网站的目录，比如你想镜像某个网站的二级目录则填写二级目录的目录名，镜像 google 用不到，默认即可.
const upstream_path = '/'
// 镜像站是否有手机访问专用网址，没有则填一样的.
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']
// 镜像站是否开启 HTTPS.
const https = true
// 文本替换.
const replace_dict = {
    '$upstream': '$custom_domain',
    '//www.google.com': ''
}
// 以下保持默认，不要动
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;
}