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|
# Guard API with OAuth 2.0 Access Token
require 'rack/oauth2'
module APIGuard
extend ActiveSupport::Concern
included do |base|
# OAuth2 Resource Server Authentication
use Rack::OAuth2::Server::Resource::Bearer, 'The API' do |request|
# The authenticator only fetches the raw token string
# Must yield access token to store it in the env
request.access_token
end
helpers HelperMethods
install_error_responders(base)
end
# Helper Methods for Grape Endpoint
module HelperMethods
# Invokes the doorkeeper guard.
#
# If token is presented and valid, then it sets @current_user.
#
# If the token does not have sufficient scopes to cover the requred scopes,
# then it raises InsufficientScopeError.
#
# If the token is expired, then it raises ExpiredError.
#
# If the token is revoked, then it raises RevokedError.
#
# If the token is not found (nil), then it raises TokenNotFoundError.
#
# Arguments:
#
# scopes: (optional) scopes required for this guard.
# Defaults to empty array.
#
def doorkeeper_guard!(scopes: [])
if (access_token = find_access_token).nil?
raise TokenNotFoundError
else
case validate_access_token(access_token, scopes)
when Oauth2::AccessTokenValidationService::INSUFFICIENT_SCOPE
raise InsufficientScopeError.new(scopes)
when Oauth2::AccessTokenValidationService::EXPIRED
raise ExpiredError
when Oauth2::AccessTokenValidationService::REVOKED
raise RevokedError
when Oauth2::AccessTokenValidationService::VALID
@current_user = User.find(access_token.resource_owner_id)
end
end
end
def doorkeeper_guard(scopes: [])
if access_token = find_access_token
case validate_access_token(access_token, scopes)
when Oauth2::AccessTokenValidationService::INSUFFICIENT_SCOPE
raise InsufficientScopeError.new(scopes)
when Oauth2::AccessTokenValidationService::EXPIRED
raise ExpiredError
when Oauth2::AccessTokenValidationService::REVOKED
raise RevokedError
when Oauth2::AccessTokenValidationService::VALID
@current_user = User.find(access_token.resource_owner_id)
end
end
end
def current_user
@current_user
end
private
def find_access_token
@access_token ||= Doorkeeper.authenticate(doorkeeper_request, Doorkeeper.configuration.access_token_methods)
end
def doorkeeper_request
@doorkeeper_request ||= ActionDispatch::Request.new(env)
end
def validate_access_token(access_token, scopes)
Oauth2::AccessTokenValidationService.validate(access_token, scopes: scopes)
end
end
module ClassMethods
# Installs the doorkeeper guard on the whole Grape API endpoint.
#
# Arguments:
#
# scopes: (optional) scopes required for this guard.
# Defaults to empty array.
#
def guard_all!(scopes: [])
before do
guard! scopes: scopes
end
end
private
def install_error_responders(base)
error_classes = [ MissingTokenError, TokenNotFoundError,
ExpiredError, RevokedError, InsufficientScopeError]
base.send :rescue_from, *error_classes, oauth2_bearer_token_error_handler
end
def oauth2_bearer_token_error_handler
Proc.new do |e|
response = case e
when MissingTokenError
Rack::OAuth2::Server::Resource::Bearer::Unauthorized.new
when TokenNotFoundError
Rack::OAuth2::Server::Resource::Bearer::Unauthorized.new(
:invalid_token,
"Bad Access Token.")
when ExpiredError
Rack::OAuth2::Server::Resource::Bearer::Unauthorized.new(
:invalid_token,
"Token is expired. You can either do re-authorization or token refresh.")
when RevokedError
Rack::OAuth2::Server::Resource::Bearer::Unauthorized.new(
:invalid_token,
"Token was revoked. You have to re-authorize from the user.")
when InsufficientScopeError
# FIXME: ForbiddenError (inherited from Bearer::Forbidden of Rack::Oauth2)
# does not include WWW-Authenticate header, which breaks the standard.
Rack::OAuth2::Server::Resource::Bearer::Forbidden.new(
:insufficient_scope,
Rack::OAuth2::Server::Resource::ErrorMethods::DEFAULT_DESCRIPTION[:insufficient_scope],
{ scope: e.scopes })
end
response.finish
end
end
end
#
# Exceptions
#
class MissingTokenError < StandardError; end
class TokenNotFoundError < StandardError; end
class ExpiredError < StandardError; end
class RevokedError < StandardError; end
class InsufficientScopeError < StandardError
attr_reader :scopes
def initialize(scopes)
@scopes = scopes
end
end
end
|
