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HTTP Token authentication

Simple Token example

class PostsController < ApplicationController
  TOKEN = "secret"

  before_action :authenticate, except: [ :index ]

  def index
    render plain: "Everyone can see me!"
  end

  def edit
    render plain: "I'm only accessible if you know the password"
  end

  private
    def authenticate
      authenticate_or_request_with_http_token do |token, options|
        # Compare the tokens in a time-constant manner, to mitigate
        # timing attacks.
        ActiveSupport::SecurityUtils.secure_compare(token, TOKEN)
      end
    end
end

Here is a more advanced Token example where only Atom feeds and the XML API are protected by HTTP token authentication. The regular HTML interface is protected by a session approach:

class ApplicationController < ActionController::Base
  before_action :set_account, :authenticate

  private
    def set_account
      @account = Account.find_by(url_name: request.subdomains.first)
    end

    def authenticate
      case request.format
      when Mime[:xml], Mime[:atom]
        if user = authenticate_with_http_token { |t, o| @account.users.authenticate(t, o) }
          @current_user = user
        else
          request_http_token_authentication
        end
      else
        if session_authenticated?
          @current_user = @account.users.find(session[:authenticated][:user_id])
        else
          redirect_to(login_url) and return false
        end
      end
    end
end

In your integration tests, you can do something like this:

def test_access_granted_from_xml
  authorization = ActionController::HttpAuthentication::Token.encode_credentials(users(:dhh).token)

  get "/notes/1.xml", headers: { 'HTTP_AUTHORIZATION' => authorization }

  assert_equal 200, status
end

On shared hosts, Apache sometimes doesn’t pass authentication headers to FCGI instances. If your environment matches this description and you cannot authenticate, try this rule in your Apache setup:

RewriteRule ^(.*)$ dispatch.fcgi [E=X-HTTP_AUTHORIZATION:%{HTTP:Authorization},QSA,L]
Namespace
Methods
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Constants

AUTHN_PAIR_DELIMITERS = /(?:,|;|\t)/
 
TOKEN_KEY = "token="
 
TOKEN_REGEX = /^(Token|Bearer)\s+/
 

Instance Public methods

authenticate(controller, &login_procedure)

If token Authorization header is present, call the login procedure with the present token and options.

Returns the return value of login_procedure if a token is found. Returns nil if no token is found.

Parameters

  • controller - ActionController::Base instance for the current request.

  • login_procedure - Proc to call if a token is present. The Proc should take two arguments:

    authenticate(controller) { |token, options| ... }

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 464
def authenticate(controller, &login_procedure)
  token, options = token_and_options(controller.request)
  unless token.blank?
    login_procedure.call(token, options)
  end
end

authentication_request(controller, realm, message = nil)

Sets a WWW-Authenticate header to let the client know a token is desired.

Returns nothing.

Parameters

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 548
def authentication_request(controller, realm, message = nil)
  message ||= "HTTP Token: Access denied.\n"
  controller.headers["WWW-Authenticate"] = %(Token realm="#{realm.tr('"', "")}")
  controller.__send__ :render, plain: message, status: :unauthorized
end

encode_credentials(token, options = {})

Encodes the given token and options into an Authorization header value.

Returns String.

Parameters

  • token - String token.

  • options - Optional Hash of the options.

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 533
def encode_credentials(token, options = {})
  values = ["#{TOKEN_KEY}#{token.to_s.inspect}"] + options.map do |key, value|
    "#{key}=#{value.to_s.inspect}"
  end
  "Token #{values * ", "}"
end

params_array_from(raw_params)

Takes raw_params and turns it into an array of parameters.

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 499
def params_array_from(raw_params)
  raw_params.map { |param| param.split %r/=(.+)?/ }
end

raw_params(auth)

This method takes an authorization body and splits up the key-value pairs by the standardized :, ;, or \t delimiters defined in AUTHN_PAIR_DELIMITERS.

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 514
def raw_params(auth)
  _raw_params = auth.sub(TOKEN_REGEX, "").split(WHITESPACED_AUTHN_PAIR_DELIMITERS)
  _raw_params.reject!(&:empty?)

  if !_raw_params.first&.start_with?(TOKEN_KEY)
    _raw_params[0] = "#{TOKEN_KEY}#{_raw_params.first}"
  end

  _raw_params
end

rewrite_param_values(array_params)

This removes the " characters wrapping the value.

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 504
def rewrite_param_values(array_params)
  array_params.each { |param| (param[1] || +"").gsub! %r/^"|"$/, "" }
end

token_and_options(request)

Parses the token and options out of the token Authorization header. The value for the Authorization header is expected to have the prefix "Token" or "Bearer". If the header looks like this:

Authorization: Token token="abc", nonce="def"

Then the returned token is "abc", and the options are {nonce: "def"}.

Returns an Array of [String, Hash] if a token is present. Returns nil if no token is found.

Parameters

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 486
def token_and_options(request)
  authorization_request = request.authorization.to_s
  if authorization_request[TOKEN_REGEX]
    params = token_params_from authorization_request
    [params.shift[1], Hash[params].with_indifferent_access]
  end
end

token_params_from(auth)

Source: show 

# File actionpack/lib/action_controller/metal/http_authentication.rb, line 494
def token_params_from(auth)
  rewrite_param_values params_array_from raw_params auth
end