Corrosion

Titanium Networks main web proxy. Successor to Alloy.

Corrosion
- Table of Contents
Installation
Basic Example
Public Deployment Example
Advanced Configuration
Middleware
- Default middleware
- Available Middleware
  - address (Request)
  - blacklist
Contributing
- Needs Improvement
Todo

Installation

npm i corrosion

Basic Example

const Corrosion = require('corrosion');
const proxy = new Corrosion();
const http = require('http')
http.createServer((req, res) => 
  proxy.request(req, res) // Request Proxy
).on('upgrade', (req, socket, head) => 
  proxy.upgrade(req, socket, head) // WebSocket Proxy
).listen(80);

Access a website by going to /prefix/gateway?url=URL.

Much more in depth one is in the demo folder.

Public Deployment Example

For implementing a Corrosion server into your production website, we recommend you follow the below configuration.

Initial Setup

index.html

<!DOCTYPE html>
<html>
    <head>
        <style>
            body {
                text-align: center;
            }
        </style>
    </head>
    <body>
        <form action="/get/gateway/" method="POST">
            <input name="url" placeholder="Search the web">
            <input type="submit" value="Go">
        </form>
    </body>
</html>

index.js

// https here is necesary for some features to work, even if this is going to be behind an SSL-providing reverse proxy.
const https = require('https');
const fs = require('fs');
const path = require('path');
const Corrosion = require('corrosion');

// you are free to use self-signed certificates here, if you plan to route through an SSL-providing reverse proxy.
const ssl = {
    key: fs.readFileSync(path.join(__dirname, '/ssl.key')),
    cert: fs.readFileSync(path.join(__dirname, '/ssl.cert')),
};
const server = https.createServer(ssl);
const proxy = new Corrosion({
    codec: 'xor', // apply basic xor encryption to url parameters in an effort to evade filters. Optional.
    prefix: '/get/' // specify the endpoint (prefix). Optional.
});

proxy.bundleScripts();

server.on('request', (request, response) => {
    if (request.url.startsWith(proxy.prefix)) return proxy.request(request, response);
    response.end(fs.readFileSync(__dirname + '/index.html', 'utf-8'));
}).on('upgrade', (clientRequest, clientSocket, clientHead) => proxy.upgrade(clientRequest, clientSocket, clientHead)).listen(8443); // port other than 443 if it is needed by other software.

In the same directory in which you saved the above files, generate some self-signed SSL certificates.

root@corrosion:~$ openssl req -nodes -new -x509 -keyout ssl.key -out ssl.cert

Testing

Run the server to ensure everything is working.

root@corrosion:~$ node index.js &; cpid=$!
root@corrosion:~$ curl -k "https://localhost:8443/get/hvtrs8%2F-ezaopne%2Ccmm" 
<html>
<head>
    <title>Example Domain</title>
...
user@corrosion:~$ kill $cpid

Now, you can setup this server to run as a service. Two popular options are PM2 (tailored for NodeJS applications) and systemd.

Persistence

PM2

root@corrosion:~$ npm i pm2 -g
root@corrosion:~$ pm2 start index.js
root@corrosion:~$ pm2 startup
root@corrosion:~$ pm2 save

systemd

[Unit]
Description=Corrosion
After=network-online.target
Wants=network-online.target systemd-networkd-wait-online.service

StartLimitIntervalSec=500
StartLimitBurst=5

[Service]
Restart=on-failure
RestartSec=5s

WorkingDirectory=/root/corrosion/path/to/server
ExecStart=/usr/bin/env node index.js

[Install]
WantedBy=multi-user.target

Save the above in /lib/systemd/system/corrosion.service

root@corrosion:~$ chmod 644 /lib/systemd/system/corrosion.service
root@corrosion:~$ systemctl daemon-reload
root@corrosion:~$ systemctl start corrosion
root@corrosion:~$ systemctl enable corrosion

Nginx Setup

Setup the Nginx reverse proxy to serve Corrosion and certbot to obtain Letsencrypt certificates.

root@corrosion:~$ apt install -y nginx python3 python3-venv libaugeas0
root@corrosion:~$ python3 -m venv /opt/certbot/
root@corrosion:~$ /opt/certbot/bin/pip install --upgrade pip
root@corrosion:~$ /opt/certbot/bin/pip install certbot certbot-nginx
root@corrosion:~$ ln -s /opt/certbot/bin/certbot /usr/bin/certbot

Now, create the following Nginx config in /etc/nginx/sites-enabled/corrosion. All of the header options are important and necesary.

server {
    root /var/www/path/to/webroot;
    server_name your.domain.com;

    location / {
        proxy_set_header Accept-Encoding "";
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Host $host:$server_port;
        proxy_set_header X-Forwarded-Server $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";   
        proxy_pass https://127.0.0.1:8443;  # the port it's listening on
        proxy_http_version 1.1; 
        proxy_set_header Host $host;
    }

    listen 80;
}

Letsencrypt

Finally, get our Letsencrypt certificates and restart nginx!

root@corrosion:~$ certbot --nginx -d <your domain>
root@corrosion:~$ systemctl restart nginx

Your site should be working now. If you want to add a custom frontend to make it usable, you should expand the index.js to serve your frontend. This can be easily integrated with Express and other NodeJS webserver frameworks. See some examples of proxy frontends that use Corrosion.

Frontend Examples

Advanced Configuration

{
   'prefix': '/get/', // String - URL Prefix
   'title': 'Woah Corrosion', // (Boolean / String) - Title used for HTML documents
   'ws': true, // Boolean - WebSocket rewriting
   'cookie': true, // Boolean - Request Cookies
   'codec': 'base64', // String - URL encoding (base64, plain, xor).
   'requestMiddleware': [Corrosion.middleware.address([0.0.0.0])] // Array - Array of [middleware](../README.md#middleware) functions for proxy request (Server). 
   'responseMiddleware': [myCustomMiddleware()] // Array - Array of [middleware](../README.md#middleware) functions for proxy response (Server).
   'standardMiddleware': true // Boolean - Use the prebuilt [middleware](../README.md#middleware) used by default (Server). 
}

Middleware

Middleware are functions that will be executed either before request or after response. These can alter the way a request is made or response is sent.

function(ctx) {r
  ctx.body; // (Request / Response) Body (Will return null if none)
  ctx.headers; // (Request / Response) Headers
  ctx.url; // WHATWG URL
  ctx.flags; // URL Flags
  ctx.origin; // Request origin
  ctx.method; // Request method
  ctx.rewrite; // Corrosion object
  ctx.statusCode; // Response status (Only available on response)
  ctx.agent; // HTTP agent
  ctx.address; // Address used to make remote request
  ctx.clientSocket; // Node.js Server Socket (Only available on upgrade)
  ctx.clientRequest; // Node.js Server Request
  ctx.clientResponse; // Node.js Server Response
  ctx.remoteResponse; // Node.js Remote Response (Only available on response)
};

Default middleware

Request
- requestHeaders
Response
- responseHeaders
- decompress
- rewriteBody

Available Middleware

address (Request)

arr Array of IP addresses to use in request.

const Corrosion = require('corrosion');
const proxy = new Corrosion({
  requestMiddleware: [
    Corrosion.middleware.address([ 
      0.0.0.0, 
      0.0.0.0 
    ]),  
  ],
});

blacklist

arr Array of hostnames to block clients from seeing.
page Block page.

const Corrosion = require('corrosion');
const proxy = new Corrosion({
  requestMiddleware: [
    Corrosion.middleware.blacklist([ 
      'example.org',
      'example.com',
    ], 'Page is blocked'),  
  ],
});

Contributing

API Documentation.

See something lacking in Corrosion that you can fix? Fork the repo, make some changes, and send in a pull request.

Needs Improvement

Code readability/commenting
Documentation (wiki)
JS Rewriter
Uniform error codes

Todo

JS Rewriter: Inject header properties (due to import statements).

Tiega91/Corrosion