Module: Ramaze::Helper::CSRF

### Home Classes Methods

### In Files

- lib/ramaze/helper/csrf.rb

### Methods

- #csrf_protection
- #generate_csrf_token
- #get_csrf_token
- #validate_csrf_token

### Included Modules

- Innate::Optioned

### Files

- Gemfile
- Rakefile

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No matching classes.

# Ramaze::Helper::CSRF

A relatively basic yet useful helper that can be used to protect your application from CSRF attacks/exploits. Note that this helper merely generates the required data, and provides several methods. You still need to manually add the token to each form.

The reason for this is because this is quite simple. Ramaze is meant as a framework that works with any given helper, ORM, template engine and so on. If we were to automatically load this helper and include (a perhaps more advanced) CSRF system that would mean that every form helper, official or third-party, would have to support that specific system. However, there's no need to panic as it's very easy to setup a basic anti CSRF system.

## Usage

In order to enable CSRF protection we need to do two things. Load the helper and create a before_all block in a controller. Take a look at the following code:

    class BaseController < Ramaze::Controller
      before_all do
        puts "Hello, before_all!"
      end
    end

This would output "Hello, before_all!" to the console upon each request. Not very useful but it does show what the before_all block can do. On to actual CSRF related code!

    class BaseController < Ramaze::Controller
      before_all do
        csrf_protection :save do
          # ....
        end
      end
    end

This example introduces an extra block that validates the current request. Whenever a user requests a controller that either extends BaseController or has it's own before_all block Ramaze will check if the current request data contains a CSRF token. Of course an if/end isn't very useful if it doesn't do anything, let's add some code.

    class BaseController < Ramaze::Controller
      before_all do
        csrf_protection :save do
          puts "Hello, unsafe data!"
        end
      end
    end

The code above checks if the current method is "save" (or any other of the provided methods) and checks if an CSRF token is supplied if the method matches. Protected methods require a token in ALL HTTP requests (GET, POST, etc). While this may seem weird since GET is generally used for safe actions it actually makes sense. Ramaze stores both the POST and GET parameters in the request.params hash. While this makes it easy to work with POST/GET data this also makes it easier to spoof POST requests using a GET request, thus this helper protects ALL request methods.

If you're a lazy person you can copy-paste the example below and adapt it to your needs.

    class BaseController < Ramaze::Controller
      before_all do
        csrf_protection :save do
          respond("The supplied CSRF token is invalid.", 401)
        end
      end
    end

### Public Instance Methods

csrf_protection(*methods, &block) click to toggle source

Method that can be used to protect the specified methods against CSRF exploits. Each protected method will require the token to be stored in a field called "csrf_token". This method will then validate that token against the current token in the session.

@param [Array] methods Array of method names that should be checked. @param [Proc] block Block that will be executed if the token is

    invalid.

@example

    # Protect "create" and "save" against CSRF exploits
    before_all do
      csrf_protection :create, :save do
        respond("GET TO DA CHOPPA!", 401)
      end
    end

    # File lib/ramaze/helper/csrf.rb, line 102
    def csrf_protection(*methods, &block)
      if methods.include?(action.name)          or methods.include?(action.name.to_sym)
        unless validate_csrf_token(request.params[CSRF.options.field_name])
          yield
        end
      end
    end

generate_csrf_token(args = {}) click to toggle source

Generate a new token and create the session array that will be used to validate the client.

Note that this method will be automatically called if no CSRF token exists.

@param [Hash] args Additional arguments that can be set such as the

    TTL.

    # File lib/ramaze/helper/csrf.rb, line 121
    def generate_csrf_token(args = {})
      random = SecureRandom.random_bytes(512)
      time   = Time.now.to_f
      token  = Digest::SHA512.hexdigest(random + time.to_s)

      # Time to store all the data we want to check later.
      session[:_csrf] = {
        :token => token,
        :ip    => request.ip,
        :agent => request.env['HTTP_USER_AGENT'],
        :host  => request.host
      }

      return
    end

get_csrf_token() click to toggle source

Retrieves the current value of the CSRF token.

@return [String] The current CSRF token. @example

    form(@data, :method => :post) do |f|
      f.input_hidden :csrf_token, get_csrf_token()
    end

    # File lib/ramaze/helper/csrf.rb, line 146
    def get_csrf_token
      if !session[:_csrf] || !self.validate_csrf_token(session[:_csrf][:token])
        self.generate_csrf_token
      end

      return session[:_csrf][:token]
    end

validate_csrf_token(input_token) click to toggle source

Validates the request based on the current session date stored in _csrf.

@param [String] input_token The CSRF token to validate. @return [TrueClass|FalseClass] @example

    before_all do
      if validate_csrf_token(request.params['csrf_token']) != true
        respond("Invalid CSRF token", 401)
      end
    end

    # File lib/ramaze/helper/csrf.rb, line 167
    def validate_csrf_token(input_token)
      # Check if the CSRF data has been generated and generate it if this
      # hasn't been done already (usually on the first request).
      if !session[:_csrf] or session[:_csrf].empty?
        self.generate_csrf_token
      end

      _csrf = session[:_csrf]

      valid = session[:_csrf][:token] == input_token &&
        _csrf[:host]  == request.host &&
        _csrf[:ip]    == request.ip &&
        _csrf[:agent] == request.env['HTTP_USER_AGENT']

      if valid
        generate_csrf_token

        return true
      else
        return false
      end
    end

[Validate]

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