Reverse-proxying blynk-server by Nginx with simple WAF

_etc_nginx_conf.d_default.conf

# empty

_etc_nginx_conf.d_default.stream

stream {
    js_import conf.d/waf.js;

    upstream blynk_https {
        server blynk:9443;
    }

    server {
        listen                    443 ssl;
        js_filter                 waf.inspect;

        proxy_pass                blynk_https;
        proxy_ssl                 on;
        proxy_ssl_verify          off;

        ssl_certificate           conf.d/star.YOURDOMAIN.com.cert.pem;
        ssl_certificate_key       conf.d/star.YOURDOMAIN.com.pkey.pem;

        ssl_session_cache         builtin:1000 shared:SSL:10m;
        ssl_protocols             TLSv1.2 TLSv1.3;
        ssl_ciphers               ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;
        ssl_prefer_server_ciphers off;
    }

    upstream blynk_http {
        server blynk:8080;
    }

    server {
        listen                    80;
        proxy_pass                blynk_http;
    }
}

_etc_nginx_conf.d_waf.js

/* !!! This is compatible with Nginx **1.19.2** or later !!! */

var ALLOW_LIST = [
    /sakurai\.youhei@gmail\.com/,
];

// https://github.com/blynkkk/blynk-server/blob/master/server/core/src/main/java/cc/blynk/server/core/protocol/enums/Command.java
var REGISTER = 1;
var LOGIN = 2;

function inspect(s) {
    s.on('upload', function(data, flags) {
        var header = parse(data);
        if (header.isAppPipeline) {
            if ((header.firstbyte === REGISTER || header.firstbyte === LOGIN) &&
                    !ALLOW_LIST.some(function(r) {return r.exec(data);})) {
                s.log('Jamming command=' + header.firstbyte + ': ' + data);
                data = data.replace(/@[^.]+\./, '@..');
                s.warn('Command was jammed: ' + data);
            }
        }
        s.off('upload');
        s.send(data);
    });
}

function parse(data) {
    var uint8array = new TextEncoder('ascii').encode(data.slice(0, 5));

    var isHttp;
    var isHardwarePipeline;
    var isAppPipeline;
    try {
        // https://github.com/blynkkk/blynk-server/blob/master/server/http-api/src/main/java/cc/blynk/server/api/http/handlers/BaseHttpAndBlynkUnificationHandler.java
        var header4Bytes = 0;
        for (var i=0; i < 4; i++) {
            header4Bytes += uint8array[i] << (8 * (3 - i));
        }
        var lastByteOfHeader = uint8array[4];

        isHttp = (header4Bytes === 1195725856 || // 'GET '
                  header4Bytes === 1347375956 || // 'POST'
                  header4Bytes === 1347769376 || // 'PUT '
                  header4Bytes === 1212498244 || // 'HEAD'
                  header4Bytes === 1330664521 || // 'OPTI'
                  header4Bytes === 1346458691 || // 'PATC'
                  header4Bytes === 1145392197 || // 'DELE'
                  header4Bytes === 1414676803 || // 'TRAC'
                  header4Bytes === 1129270862);  // 'CONN'
        isHardwarePipeline = (lastByteOfHeader === 32 &&
                              (header4Bytes === 486539520 || header4Bytes === 33554688));
        isAppPipeline = !isHttp && !isHardwarePipeline;
    } catch (e) {
        isHttp = isHardwarePipeline = isAppPipeline = false;
    }

    return {firstbyte: uint8array[0],
            isHttp: isHttp,
            isHardwarePipeline: isHardwarePipeline,
            isAppPipeline: isAppPipeline};
}

export default {inspect}

docker-compose.yml

version: "3.5"

services:

  blynk:
    image: YOUR-BLYNK-IMAGE
    restart: unless-stopped
    entrypoint: java -jar /blynk/server.jar

  nginx:
    image: nginx:1.19.2
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - /YOUR/PATH/TO/etc/nginx/conf.d:/etc/nginx/conf.d
      - /var/log/nginx:/var/log/nginx
    restart: unless-stopped
    command: >-
        nginx -g "
        load_module modules/ngx_stream_js_module.so;
        include /etc/nginx/conf.d/default.stream;
        daemon off;
        "
 

I guess http block is not possible here. Packet doesn't have HTTP specifications ( https://github.com/blynkkk/blynk-server/blob/v0.41.15/server/http-api/src/main/java/cc/blynk/server/api/http/handlers/BaseHttpAndBlynkUnificationHandler.java ). For instance you can't use Host header (server_name) to combine this with other domains in Nginx configuration.

It's stream solution provided via Nginx.