class OpenID::Consumer
OpenID
support for Relying Parties (aka Consumers).
This module documents the main interface with the OpenID
consumer library. The only part of the library which has to be used and isn't documented in full here is the store required to create an Consumer
instance.
OVERVIEW¶ ↑
The OpenID
identity verification process most commonly uses the following steps, as visible to the user of this library:
-
The user enters their
OpenID
into a field on the consumer's site, and hits a login button. -
The consumer site discovers the user's
OpenID
provider using theYadis
protocol. -
The consumer site sends the browser a redirect to the
OpenID
provider. This is the authentication request as described in theOpenID
specification. -
The
OpenID
provider's site sends the browser a redirect back to the consumer site. This redirect contains the provider's response to the authentication request.
The most important part of the flow to note is the consumer's site must handle two separate HTTP requests in order to perform the full identity check.
LIBRARY DESIGN¶ ↑
This consumer library is designed with that flow in mind. The goal is to make it as easy as possible to perform the above steps securely.
At a high level, there are two important parts in the consumer library. The first important part is this module, which contains the interface to actually use this library. The second is openid/store/interface.rb, which describes the interface to use if you need to create a custom method for storing the state this library needs to maintain between requests.
In general, the second part is less important for users of the library to know about, as several implementations are provided which cover a wide variety of situations in which consumers may use the library.
The Consumer
class has methods corresponding to the actions necessary in each of steps 2, 3, and 4 described in the overview. Use of this library should be as easy as creating an Consumer
instance and calling the methods appropriate for the action the site wants to take.
This library automatically detects which version of the OpenID
protocol should be used for a transaction and constructs the proper requests and responses. Users of this library do not need to worry about supporting multiple protocol versions; the library supports them implicitly. Depending on the version of the protocol in use, the OpenID
transaction may be more secure. See the OpenID
specifications for more information.
SESSIONS, STORES, AND STATELESS MODE¶ ↑
The Consumer
object keeps track of two types of state:
-
State of the user's current authentication attempt. Things like the identity URL, the list of endpoints discovered for that URL, and in case where some endpoints are unreachable, the list of endpoints already tried. This state needs to be held from
Consumer.begin()
toConsumer.complete()
, but it is only applicable to a single session with a single user agent, and at the end of the authentication process (i.e. when an OP replies with eitherid_res
. orcancel
it may be discarded. -
State of relationships with servers, i.e. shared secrets (associations) with servers and nonces seen on signed messages. This information should persist from one session to the next and should not be bound to a particular user-agent.
These two types of storage are reflected in the first two arguments of Consumer's constructor, session
and store
. session
is a dict-like object and we hope your web framework provides you with one of these bound to the user agent. store
is an instance of Store
.
Since the store does hold secrets shared between your application and the OpenID
provider, you should be careful about how you use it in a shared hosting environment. If the filesystem or database permissions of your web host allow strangers to read from them, do not store your data there! If you have no safe place to store your data, construct your consumer with nil for the store, and it will operate only in stateless mode. Stateless mode may be slower, put more load on the OpenID
provider, and trusts the provider to keep you safe from replay attacks.
Several store implementation are provided, and the interface is fully documented so that custom stores can be used as well. See the documentation for the Consumer
class for more information on the interface for stores. The implementations that are provided allow the consumer site to store the necessary data in several different ways, including several SQL databases and normal files on disk.
IMMEDIATE MODE¶ ↑
In the flow described above, the user may need to confirm to the OpenID
provider that it's ok to disclose his or her identity. The provider may draw pages asking for information from the user before it redirects the browser back to the consumer's site. This is generally transparent to the consumer site, so it is typically ignored as an implementation detail.
There can be times, however, where the consumer site wants to get a response immediately. When this is the case, the consumer can put the library in immediate mode. In immediate mode, there is an extra response possible from the server, which is essentially the server reporting that it doesn't have enough information to answer the question yet.
USING THIS LIBRARY¶ ↑
Integrating this library into an application is usually a relatively straightforward process. The process should basically follow this plan:
Add an OpenID
login field somewhere on your site. When an OpenID
is entered in that field and the form is submitted, it should make a request to the site that includes that OpenID
URL.
First, the application should instantiate a Consumer
with a session for per-user state and store for shared state using the store of choice.
Next, the application should call the begin
method of Consumer
instance. This method takes the OpenID
URL as entered by the user. The begin
method returns a CheckIDRequest
object.
Next, the application should call the redirect_url method on the CheckIDRequest
object. The parameter return_to
is the URL that the OpenID
server will send the user back to after attempting to verify his or her identity. The realm
parameter is the URL (or URL pattern) that identifies your web site to the user when he or she is authorizing it. Send a redirect to the resulting URL to the user's browser.
That's the first half of the authentication process. The second half of the process is done after the user's OpenID
Provider sends the user's browser a redirect back to your site to complete their login.
When that happens, the user will contact your site at the URL given as the return_to
URL to the redirect_url call made above. The request will have several query parameters added to the URL by the OpenID
provider as the information necessary to finish the request.
Get a Consumer
instance with the same session and store as before and call its complete() method, passing in all the received query arguments and URL currently being handled.
There are multiple possible return types possible from that method. These indicate the whether or not the login was successful, and include any additional information appropriate for their type.
Constants
- CANCEL
Code returned by OpenIDConsumer.complete_auth when the user cancels the operation from the server.
- FAILURE
Code OpenID::OpenIDConsumer.complete_auth returns when the value it received indicated an invalid login.
- SETUP_NEEDED
Code returned by OpenID::OpenIDConsumer.complete_auth when the OpenIDConsumer instance is in immediate mode and ther server sends back a URL for the user to login with.
- SUCCESS
Code returned when either the of the OpenID::OpenIDConsumer.begin_auth or OpenID::OpenIDConsumer.complete_auth methods return successfully.
Attributes
Public Class Methods
Initialize a Consumer
instance.
You should create a new instance of the Consumer
object with every HTTP request that handles OpenID
transactions.
session: the session object to use to store request information. The session should behave like a hash.
store: an object that implements the interface in Store
.
# File lib/openid/consumer.rb, line 192 def initialize(session, store) @origin_session = session @session = Session.new(session, OpenID::OpenIDServiceEndpoint) @store = store @session_key_prefix = 'OpenID::Consumer::' end
See openid1_return_to_claimed_id_name
=
# File lib/openid/consumer/idres.rb, line 42 def self.openid1_return_to_claimed_id_name @openid1_return_to_claimed_id_name end
Set the name of the query parameter that this library will use to thread the requested URL through an OpenID
1 transaction (for use when verifying discovered information). It will be appended to the return_to URL.
# File lib/openid/consumer/idres.rb, line 37 def self.openid1_return_to_claimed_id_name=(query_arg_name) @openid1_return_to_claimed_id_name = query_arg_name end
See openid1_return_to_nonce_name
= documentation
# File lib/openid/consumer/idres.rb, line 29 def self.openid1_return_to_nonce_name @openid1_return_to_nonce_name end
Set the name of the query parameter that this library will use to thread a nonce through an OpenID
1 transaction. It will be appended to the return_to URL.
# File lib/openid/consumer/idres.rb, line 24 def self.openid1_return_to_nonce_name=(query_arg_name) @openid1_return_to_nonce_name = query_arg_name end
Public Instance Methods
Start the OpenID
authentication process. See steps 1-2 in the overview for the Consumer
class.
user_url: Identity URL given by the user. This method performs a textual transformation of the URL to try and make sure it is normalized. For example, a user_url of example.com will be normalized to example.com/ normalizing and resolving any redirects the server might issue.
anonymous: A boolean value. Whether to make an anonymous request of the OpenID
provider. Such a request does not ask for an authorization assertion for an OpenID
identifier, but may be used with extensions to pass other data. e.g. “I don't care who you are, but I'd like to know your time zone.”
Returns a CheckIDRequest
object containing the discovered information, with a method for building a redirect URL to the server, as described in step 3 of the overview. This object may also be used to add extension arguments to the request, using its add_extension_arg method.
Raises DiscoveryFailure
when no OpenID
server can be found for this URL.
# File lib/openid/consumer.rb, line 222 def begin(openid_identifier, anonymous=false) manager = discovery_manager(openid_identifier) service = manager.get_next_service(&method(:discover)) if service.nil? raise DiscoveryFailure.new("No usable OpenID services were found "\ "for #{openid_identifier.inspect}", nil) else begin_without_discovery(service, anonymous) end end
Start OpenID
verification without doing OpenID
server discovery. This method is used internally by Consumer.begin()
after discovery is performed, and exists to provide an interface for library users needing to perform their own discovery.
service: an OpenID
service endpoint descriptor. This object and factories for it are found in the openid/consumer/discovery.rb module.
Returns an OpenID
authentication request object.
# File lib/openid/consumer.rb, line 244 def begin_without_discovery(service, anonymous) assoc = association_manager(service).get_association checkid_request = CheckIDRequest.new(assoc, service) checkid_request.anonymous = anonymous if service.compatibility_mode rt_args = checkid_request.return_to_args rt_args[Consumer.openid1_return_to_nonce_name] = Nonce.mk_nonce rt_args[Consumer.openid1_return_to_claimed_id_name] = service.claimed_id end self.last_requested_endpoint = service return checkid_request end
Returns a subclass of Response
. The type of response is indicated by the status attribute, which will be one of SUCCESS
, CANCEL
, FAILURE
, or SETUP_NEEDED
.
# File lib/openid/consumer.rb, line 283 def complete(query, current_url) message = Message.from_post_args(query) mode = message.get_arg(OPENID_NS, 'mode', 'invalid') begin meth = method('complete_' + mode) rescue NameError meth = method(:complete_invalid) end response = meth.call(message, current_url) cleanup_last_requested_endpoint if [SUCCESS, CANCEL].member?(response.status) cleanup_session end return response end
Protected Instance Methods
# File lib/openid/consumer.rb, line 342 def association_manager(service) AssociationManager.new(@store, service.server_url, service.compatibility_mode, negotiator) end
# File lib/openid/consumer.rb, line 321 def cleanup_last_requested_endpoint @session[session_key('last_requested_endpoint')] = nil end
# File lib/openid/consumer.rb, line 329 def cleanup_session discovery_manager(nil).cleanup(true) end
# File lib/openid/consumer.rb, line 357 def complete_cancel(unused_message, unused_return_to) return CancelResponse.new(last_requested_endpoint) end
# File lib/openid/consumer.rb, line 361 def complete_error(message, unused_return_to) error = message.get_arg(OPENID_NS, 'error') contact = message.get_arg(OPENID_NS, 'contact') reference = message.get_arg(OPENID_NS, 'reference') return FailureResponse.new(last_requested_endpoint, error, contact, reference) end
# File lib/openid/consumer.rb, line 379 def complete_id_res(message, current_url) if message.is_openid1 setup_url = message.get_arg(OPENID_NS, 'user_setup_url') if !setup_url.nil? return SetupNeededResponse.new(last_requested_endpoint, setup_url) end end begin idres = handle_idres(message, current_url) rescue OpenIDError => why return FailureResponse.new(last_requested_endpoint, why.message) else return SuccessResponse.new(idres.endpoint, message, idres.signed_fields) end end
# File lib/openid/consumer.rb, line 351 def complete_invalid(message, unused_return_to) mode = message.get_arg(OPENID_NS, 'mode', '<No mode set>') return FailureResponse.new(last_requested_endpoint, "Invalid openid.mode: #{mode}") end
# File lib/openid/consumer.rb, line 370 def complete_setup_needed(message, unused_return_to) if message.is_openid1 return complete_invalid(message, nil) else setup_url = message.get_arg(OPENID2_NS, 'user_setup_url') return SetupNeededResponse.new(last_requested_endpoint, setup_url) end end
# File lib/openid/consumer.rb, line 334 def discover(identifier) OpenID.discover(identifier) end
# File lib/openid/consumer.rb, line 325 def discovery_manager(openid_identifier) DiscoveryManager.new(@origin_session, openid_identifier, @session_key_prefix) end
# File lib/openid/consumer.rb, line 347 def handle_idres(message, current_url) IdResHandler.new(message, current_url, @store, last_requested_endpoint) end
# File lib/openid/consumer.rb, line 313 def last_requested_endpoint session_get('last_requested_endpoint') end
# File lib/openid/consumer.rb, line 317 def last_requested_endpoint=(endpoint) session_set('last_requested_endpoint', endpoint) end
# File lib/openid/consumer.rb, line 338 def negotiator DefaultNegotiator end
# File lib/openid/consumer.rb, line 301 def session_get(name) @session[session_key(name)] end
# File lib/openid/consumer.rb, line 309 def session_key(suffix) @session_key_prefix + suffix end
# File lib/openid/consumer.rb, line 305 def session_set(name, val) @session[session_key(name)] = val end