使用cloudflare workers搭建谷歌镜像的方法

众所周知，由于谷歌的民用服务大多数退出了中国大陆，导致访问谷歌时需要一些其它技术手段来访问，下面笔者就介绍一下利用cloudflare workers搭建谷歌镜像的方法。

在cloudflare的管理后台dash.cloudflare.com中找到workers选项

进入以后，选择建立worker

在进去以后的页面把指令码改为以下内容

// 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;
}