Implements basic claims request parameter (Closes #11)

.rubocop.yml

@@ -0,0 +1,10 @@
+AllCops:
+  NewCops: enable
+  TargetRubyVersion: 3.0
+
+Naming/RescuedExceptionsVariableName:
+  Enabled: Yes
+  PreferredName: error
+
+Style/Documentation:
+  Enabled: No

app/controllers/oidc_provider/authorizations_controller.rb

@@ -6,14 +6,14 @@ class AuthorizationsController < ApplicationController
 
     before_action :require_oauth_request
     before_action :require_response_type_code
+    before_action :ensure_claims_is_valid
     before_action :require_client
     before_action :reset_login_if_necessary
     before_action :require_authentication
+    before_action :print_scopes_and_claims
 
     def create
-      Rails.logger.info "scopes: #{requested_scopes}"
-
-      authorization = build_authorization_with(requested_scopes)
+      authorization = build_authorization
 
       oauth_response.code = authorization.code
       oauth_response.redirect_uri = @redirect_uri
@@ -26,13 +26,39 @@ def create
 
     private
 
-    def build_authorization_with(scopes)
-      Authorization.create(
+    def build_authorization
+      authorization = Authorization.new(
         client_id: @client.identifier,
         nonce: oauth_request.nonce,
-        scopes: scopes,
+        scopes: requested_scopes,
         account: oidc_current_account
       )
+
+      oauth_request.claims && authorization.claims = JSON.parse(oauth_request.claims)
+
+      authorization.save
+      authorization
+    end
+
+    def ensure_claims_is_valid
+      return true unless oauth_request.claims
+
+      validate_json_is_a_hash!(parse_claims_as_json!)
+    rescue Errors::InvalidClaimsFormatError => error
+      Rails.logger.error "Invalid claims passed: #{error.message}"
+      oauth_request.invalid_request! 'invalid claims format'
+    end
+
+    def parse_claims_as_json!
+      JSON.parse(oauth_request.claims)
+    rescue JSON::ParserError => error
+      Rails.logger.error "Invalid claims passed: #{error.message}"
+      oauth_request.invalid_request! 'claims just be a JSON'
+    end
+
+    def print_scopes_and_claims
+      Rails.logger.info "scopes: #{requested_scopes}"
+      Rails.logger.info "claims: #{oauth_request.claims}"
     end
 
     def require_client
@@ -60,5 +86,20 @@ def reset_login_if_necessary
         redirect_to url_for(request.query_parameters.except(:prompt))
       end
     end
+
+    # Recursive method validating the given `json` is a hash of hashes
+    def validate_json_is_a_hash!(json)
+      # When reaching the end of the json/hash path, we're getting a `nil`, or
+      # a String (hard coded value) or the `essential` boolean value (not yet
+      # implemented).
+      #
+      # For example, when the previous call of this method received
+      # `{ email: nil }`, the current call of this method receives `nil`.
+      return if json.nil? || json.is_a?(String)
+
+      raise Errors::InvalidClaimsFormatError unless json.is_a?(Hash)
+
+      json.each_key { |key| validate_json_is_a_hash!(json[key]) }
+    end
   end
 end

app/controllers/oidc_provider/discovery_controller.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module OIDCProvider
   class DiscoveryController < ApplicationController
     def show
@@ -7,7 +9,7 @@ def show
       when 'openid-configuration'
         openid_configuration
       else
-        render plain: "Not found", status: :not_found
+        render plain: 'Not found', status: :not_found
       end
     end
 
@@ -21,27 +23,27 @@ def webfinger_discovery
         }]
       }
       jrd[:subject] = params[:resource] if params[:resource].present?
-      render json: jrd, content_type: "application/jrd+json"
+      render json: jrd, content_type: 'application/jrd+json'
     end
 
     def openid_configuration
       config = OpenIDConnect::Discovery::Provider::Config::Response.new(
-        issuer: OIDCProvider.issuer,
         authorization_endpoint: authorizations_url(host: OIDCProvider.issuer),
-        token_endpoint: tokens_url(host: OIDCProvider.issuer),
-        userinfo_endpoint: user_info_url(host: OIDCProvider.issuer),
+        claims_parameter_supported: true,
+        claims_supported: OIDCProvider.supported_claims,
         end_session_endpoint: end_session_url(host: OIDCProvider.issuer),
+        grant_types_supported: [:authorization_code],
+        id_token_signing_alg_values_supported: [:RS256],
+        issuer: OIDCProvider.issuer,
         jwks_uri: jwks_url(host: OIDCProvider.issuer),
-        scopes_supported: ["openid"] + OIDCProvider.supported_scopes.map(&:name),
         response_types_supported: [:code],
-        grant_types_supported: [:authorization_code],
+        scopes_supported: OIDCProvider.supported_scopes.map(&:name),
         subject_types_supported: [:public],
-        id_token_signing_alg_values_supported: [:RS256],
-        token_endpoint_auth_methods_supported: ['client_secret_basic', 'client_secret_post'],
-        claims_supported: ['sub', 'iss', 'name', 'email']
+        token_endpoint: tokens_url(host: OIDCProvider.issuer),
+        token_endpoint_auth_methods_supported: %w[client_secret_basic client_secret_post],
+        userinfo_endpoint: user_info_url(host: OIDCProvider.issuer)
       )
       render json: config
     end
   end
-
-end
+end

app/controllers/oidc_provider/user_infos_controller.rb

@@ -1,9 +1,18 @@
+# frozen_string_literal: true
+
 module OIDCProvider
   class UserInfosController < ApplicationController
     before_action :require_access_token
 
     def show
-      render json: AccountToUserInfo.new.(current_token.authorization.account, current_token.authorization.scopes)
+      render json: user_info
+    end
+
+    private
+
+    def user_info
+      AccountToUserInfo.new(current_token.authorization.user_info_scopes)
+                       .call(current_token.authorization.account)
     end
   end
-end
+end

app/models/oidc_provider/authorization.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module OIDCProvider
   class Authorization < ApplicationRecord
     belongs_to :account, class_name: OIDCProvider.account_class
@@ -10,25 +12,72 @@ class Authorization < ApplicationRecord
     attribute :expires_at, :datetime, default: -> { 5.minutes.from_now }
 
     serialize :scopes, JSON
+    serialize :claims, JSON
+
+    def access_token
+      super || (expire! && generate_access_token!)
+    end
+
+    def scope_configs_for(type)
+      if claims_request_for?(type)
+        build_scope_configs_from_claims_request_for(type)
+      else
+        type == :id_token ? [open_id_scope_config] : user_info_scope_configs
+      end
+    end
 
     def expire!
       self.expires_at = Time.now
-      self.save!
-    end
 
-    def access_token
-      super || expire! && generate_access_token!
+      save!
     end
 
     def id_token
       super || generate_id_token!
     end
 
+    def user_info_scopes
+      scopes - ['openid']
+    end
+
     private
 
+    def build_scope_config_for(scope, type, key)
+      ScopeConfig.new(scope, [key.to_sym]).tap do |scope_config|
+        scope_config.add_force_claim(key.to_sym => claims[type.to_s][key])
+      end
+    end
+
+    def build_scope_configs_from_claims_request_for(type)
+      # No matter the `claims` config, when we are about to create an IdToken
+      # response, we need the OpenID scope claims since there's mandatory ones
+      scope_configs = type == :id_token ? [open_id_scope_config] : []
+
+      claims[type.to_s].each_key do |key|
+        scopes_with_claim = OIDCProvider.find_all_scopes_with_claim(key)
+
+        next unless scope_found?(scopes_with_claim, key)
+
+        warn_when_many_scopes_found_in(scopes_with_claim, key, type)
+
+        scope = scopes_with_claim.first
+
+        next unless scope_has_been_requested?(scope)
+
+        scope_configs << build_scope_config_for(scope, type, key)
+      end
+
+      scope_configs
+    end
+
+    def claims_request_for?(type)
+      return false unless claims
+
+      claims.keys.include?(type.to_s)
+    end
+
     def generate_access_token!
-      token = create_access_token!
-      token
+      create_access_token!
     end
 
     def generate_id_token!
@@ -37,5 +86,51 @@ def generate_id_token!
       token.save!
       token
     end
+
+    def open_id_scope_config
+      scope = OIDCProvider.find_scope(OIDCProvider::Scopes::OpenID)
+
+      ScopeConfig.new(scope, scope.claims)
+    end
+
+    def scope_found?(scopes_with_claim, key)
+      return true unless scopes_with_claim.empty?
+
+      Rails.logger.warn(
+        "WARNING: No scope found providing the '#{key}' claim. " \
+        'OIDCProvider will skip it.'
+      )
+
+      false
+    end
+
+    def scope_has_been_requested?(scope)
+      return true if scopes.include?(scope.name)
+
+      Rails.logger.warn(
+        "WARNING: The scope #{scope.name} has not being requested " \
+        'on authorization creation, there fore OIDCProvider will skip it.'
+      )
+
+      false
+    end
+
+    def user_info_scope_configs
+      user_info_scopes.map do |scope_name|
+        scope = OIDCProvider.find_scope(scope_name)
+
+        ScopeConfig.new(scope, scope.claims)
+      end
+    end
+
+    def warn_when_many_scopes_found_in(scopes_with_claim, key, type)
+      return unless scopes_with_claim.size > 1
+
+      Rails.logger.warn(
+        "WARNING: Scopes #{scopes_with_claim.map(&:name).to_sentence} " \
+        "have the #{key} claim declared. OIDCProvider will use the first " \
+        "one to populate the #{type} response."
+      )
+    end
   end
 end

app/models/oidc_provider/id_token.rb

@@ -11,14 +11,7 @@ class IdToken < ApplicationRecord
     delegate :account, to: :authorization
 
     def to_response_object
-      OpenIDConnect::ResponseObject::IdToken.new(
-        iss: OIDCProvider.issuer,
-        sub: account.send(OIDCProvider.account_identifier),
-        aud: authorization.client_id,
-        nonce: nonce,
-        exp: expires_at.to_i,
-        iat: created_at.to_i
-      )
+      OpenIDConnect::ResponseObject::IdToken.new(id_token_attributes)
     end
 
     def to_jwt
@@ -27,6 +20,57 @@ def to_jwt
 
     private
 
+    # Return a Struct accepting all the possible attributes from an instance of
+    # the OpenIDConnect::ResponseObject::IdToken class used to collect the scope
+    # values and populate the OpenIDConnect::ResponseObject::IdToken instance
+    # that will be returned by the above `to_response_object`.
+    #
+    # At first I used an OpenStruct but since it has been officially discouraged
+    # for performance, version compatibility, and potential security issues,
+    # a `Struct` with predefined attributes is used instead.
+    # See https://docs.ruby-lang.org/en/3.0/OpenStruct.html#class-OpenStruct-label-Caveats
+    def build_id_token_struct
+      Struct.new(*OpenIDConnect::ResponseObject::IdToken.all_attributes)
+    end
+
+    def build_user_info_struct
+      Struct.new(*OpenIDConnect::ResponseObject::UserInfo.all_attributes)
+    end
+
+    def build_values_from_scope(scope_config)
+      attributes, context = prepare_response_object_builder_from(scope_config)
+
+      ResponseObjectBuilder.new(attributes, context, scope_config.requested_claims)
+                           .run(&scope_config.scope.work)
+
+      response_attributes = attributes.to_h.compact
+
+      scope_config.force_claim.each do |key, value|
+        response_attributes[key] = value
+      end
+
+      response_attributes
+    end
+
+    def id_token_attributes
+      scope_configs.each_with_object({}) do |scope_config, memo|
+        output = build_values_from_scope(scope_config)
+        memo.merge!(output)
+      end
+    end
+
+    def prepare_response_object_builder_from(scope_config)
+      if scope_config.name == OIDCProvider::Scopes::OpenID
+        [build_id_token_struct.new, self]
+      else
+        [build_user_info_struct.new, account]
+      end
+    end
+
+    def scope_configs
+      authorization.scope_configs_for(:id_token)
+    end
+
     class << self
       def config
         {

db/migrate/20170928211111_create_oidc_provider_authorizations.rb

@@ -1,11 +1,14 @@
+# frozen_string_literal: true
+
 class CreateOIDCProviderAuthorizations < ActiveRecord::Migration[5.1]
   def change
     create_table :oidc_provider_authorizations do |t|
-      t.references :account, foreign_key: {to_table: OIDCProvider.account_class.tableize}, null: false
+      t.references :account, foreign_key: { to_table: OIDCProvider.account_class.tableize }, null: false
       t.string :client_id, null: false
       t.string :nonce
       t.string :code, null: false
       t.text :scopes, null: false
+      t.text :claims
       t.datetime :expires_at, null: false
 
       t.timestamps