Little faye server with hmac authentication

application_helper.rb

  def hmac_token(channel)
    ident = {
      user: current_user.id,
      timestamp: Time.now.to_i,
      channel: channel
    }
    puts "#{ident[:user]}:#{ident[:timestamp]}:#{ident[:channel]}"
    digest = OpenSSL::HMAC.new(ENV['FAYE_SECRET_KEY'] || 'whocares?', 'SHA512')
    digest << "#{ident[:user]}:#{ident[:timestamp]}:#{ident[:channel]}"
    ident[:token] = digest.hexdigest
    raw ident.to_json
  end

client.js

  var ident = <%= hmac_token '/channel' %>
  var Logger = {
    incoming: function(message, callback) {
      console.log('incoming', message);
      callback(message);
    },
    outgoing: function(message, callback) {
      console.log('outgoing', message);
      if (message.channel !== '/meta/subscribe') return callback(message);
      message.ext = message.ext || {};
      message.ext.ident = ident;
      callback(message);
    }
  };

  var client = new Faye.Client('http://localhost:8080/');
  client.addExtension(Logger);
  client.subscribe('/channel',
    function(message) {
      console.log(message)
    }
  ).then(
    function() {
      console.log('connected')
    }
  );

faye.rb

require 'faye'
require 'openssl'

module Rack #disable rack:lint which crashes when using faye
  class Lint
    def call(env = nil)
      @app.call(env)
    end
  end
end

Faye::WebSocket.load_adapter('thin') #TODO resolve issue with rainbows


class HMACAuth

  def incoming(message, callback)

    unless message['channel'] == '/meta/subscribe'
      return callback.call(message)
    end

    begin
      subscription = message['subscription']
      ident = message['ext'] && message['ext']['ident']

      if ident['timestamp'] + 86400 < Time.now.to_i
          message['error'] = 'Invalid timestap, to old'
      end

      if ident['channel'] != subscription
        message['error'] = 'Invalid channel for given token'
      end

      if token(ident) != ident['token']
        message['error'] = 'Invalid subscription auth token'
      end

    rescue Exception => e
      message['error'] = e.to_s
    end

    callback.call(message)
  end

  private

  def token(ident, secret=ENV['FAYE_SECRET_KEY'] || 'whocares?')
    digest = OpenSSL::HMAC.new(secret, 'SHA512')
    digest << "#{ident['user']}:#{ident['timestamp']}:#{ident['channel']}"
    digest.hexdigest
  end

end

server = Faye::RackAdapter.new(mount: '/', timeout: 25, extensions:[HMACAuth.new])
run server