利用cloudflareWorkers制作Google镜像站

// Website you intended to retrieve for users.
const upstream = 'www.google.com'

// Custom pathname for the upstream website.
const upstream_path = '/'

// Website you intended to retrieve for users using mobile devices.
const upstream_mobile = 'www.google.com'

// Countries and regions where you wish to suspend your service.
const blocked_region = ['KP', 'SY', 'PK', 'CU']

// IP addresses which you wish to block from using your service.
const blocked_ip_address = ['0.0.0.0', '127.0.0.1']

// Whether to use HTTPS protocol for upstream address.
const https = true

// Whether to disable cache.
const disable_cache = true

// Replace texts.
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;
​        
​        if (disable_cache) {
​            new_response_headers.set('Cache-Control', 'no-store');
​        }
​    
​        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');
​        
​        if(new_response_headers.get("x-pjax-url")) {
​            new_response_headers.set("x-pjax-url", response_headers.get("x-pjax-url").replace("//" + upstream_domain, "//" + url_hostname));
​        }
​        
​        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;
}