反代github解决gitalk网络问题

gitalk网络问题的根源是gitalk基于github仓库进行评论记录和展示，如果无法访问到github的地址就没办法使用gitalk评论。

0x1 反代github

秉着少花钱甚至不花钱的基本原则，解决方法的原理就是使用cloudflare的workers对github进行代理，但是默认的workers.dev域名已经被墙，所以还需要申请一个免费的域名，然后再cloudflare上托管，再配置域名访问workers服务。

1 注册免费域名

参考：https://www.youtube.com/watch?v=mC8H4Y05ccM

• 域名申请：https://www.freenom.com/

• 当前ip查询：https://www.ipaddress.com/

• 美国身份证生成：https://www.meiguodizhi.com/

• cloudflare：https://www.cloudflare.com/zh-cn/

美国节点，最好是原生相对干净的节点，全局模式或者浏览器全局代理，这里不过多解释，浏览器无痕模式，先打开当前ip查询一下自己ip的城市（挂代理下的美国ip），然后根据ip的城市在美国身份证生成网址生成美国身份信息，然后去申请免费域名，输入域名之后会让填邮箱验证，建议使用gmail邮箱，同样在全局代理下，去邮箱打开freenom邮件的链接，会让填写信息，照着生成的美国身份填就行，手机号记得把“-”去掉再输入。

然后在自己的domain中将dns服务器修改为clouflare的域名服务器，然后在cloudflare里面接管一下，不知道的可以在网上搜索一下·，挺简单的。

2 创建反代workers

参考：https://www.j000e.com/cloudflare/cfworkers_reverse_proxy.html

这里直接丢workers的代码，我这里是反代的api.github.com。

// Website you intended to retrieve for users.
const upstream = 'api.github.com'

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

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

// Countries and regions where you wish to suspend your service.
const blocked_region = []

// 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',
}

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);
        let body = request.body

        new_request_headers.set('Host', upstream_domain);
        new_request_headers.set('Referer', url.protocol + '//' + url_hostname);

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

        connection_upgrade = new_request_headers.get("Upgrade");
        if (connection_upgrade && connection_upgrade.toLowerCase() == "websocket") {
            return original_response;
        }

        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 != null && 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;
}

3 域名指向workers

在workers的配置页面有个触发器，可以设置自定义域名，但是要求必须是当前cloudflare账户托管的域名才行。

0x02 魔改gitalk

魔改的方法很多种，最简单的就是将gitalk的js文件中的api.github.com改成自己的workers域名，另一种方法就是在页面上增加ajax-hook，自定义规则将api.github.com的请求域名改成自己的workers域名，这样以后更新gitalk或者使用cdn加载时，不用动js文件，下面是简单的代码示例。

ajax-hook: https://github.com/wendux/ajax-hook

<script src="https://unpkg.com/[email protected]/dist/ajaxhook.min.js"></script>
<script>
    ah.proxy({
        onRequest: (config,handler) => {
            let api = '自己的反代workers域名';
            config.url = config.url.replace("api.github.com", api);
            handler.next(config);
        }
    });
</script>