NAME

LWP::Authen::OAuth2::ServiceProvider - ServiceProvider base class

VERSION

version 0.19

SYNOPSIS

This is a base module for representing an OAuth 2 service provider. It is implicitly constructed from the parameters to LWP::Authen::OAuth2->new, and is automatically delegated to when needed.

The first way to try to specify the service provider is with the parameters service_provider and possibly client_type:

    LWP::Authen::OAuth2->new(
        ...
        service_provider => "Foo",
        client_type => "bar", # optional
        ...
    );

The first parameter will cause LWP::Authen::OAuth2::ServiceProvider to look for either LWP::Authen::OAuth2::ServiceProvider::Foo, or if that is not found, for Foo. (If neither is present, an exception will be thrown.) The second parameter will be passed to that module which can choose to customize the service provider behavior based on the client_type.

The other way to specify the service provider is by passing in sufficient parameters to create a custom one on the fly:

    LWP::Authen::OAuth2->new(
        ...
        authorization_endpoint => $authorization_endpoint,
        token_endpoint => $token_endpoint,

        # These are optional but let you get the typo checks of strict mode
        authorization_required_params => [...],
        authorization_optional_params => [...],
        ...
    );

See LWP::Authen::OAuth2::Overview if you are uncertain how to figure out the Authorization Endpoint and Token Endpoint from the service provider's documentation.

KNOWN SERVICE PROVIDERS

The following service providers are provided in this distribution, with hopefully useful configuration and documentation:

LWP::Authen::OAuth2::ServiceProvider::Dwolla

LWP::Authen::OAuth2::ServiceProvider::Google

LWP::Authen::OAuth2::ServiceProvider::Line

LWP::Authen::OAuth2::ServiceProvider::Strava

LWP::Authen::OAuth2::ServiceProvider::Withings

LWP::Authen::OAuth2::ServiceProvider::Yahoo

SUBCLASSING

Support for new service providers can be added with subclasses. To do that it is useful to understand how things get delegated under the hood.

First LWP::Authen::OAuth2 asks LWP::Authen::OAuth2::ServiceProvider to construct a service provider. Based on the service_provider argument, it figures out that it needs to load and use your base class. A service provider might need different behaviors for different client types. You are free to take the client type and dynamically decide which subclass of yours will be loaded instead to get the correct flow. Should your subclass need to, it can decide that that a subclass of LWP::Authen::OAuth2 should be used that actually knows about request types that are specific to your service provider. Hopefully most service providers do not need this, but some do.

For all of the potential complexity that is supported, most service provider subclasses should be simple. Just state what fields differ from the specification for specific requests and client types, then include documentation. However even crazy service providers should be supportable.

Here are the methods that were designed to be useful to override. See the source if you have a need that none of these address. But if you can do what you need to do through these, please do.

authorization_endpoint

Takes no arguments, returns the URL for the Authorization Endpoint for the service provider. Your subclass cannot function without this.

token_endpoint

Takes no arguments, returns the URL for the Token Endpoint for the service provider. Your subclass cannot function without this.

client_type_class

This method receives your class name and the passed in client_type. It is supposed to make sure that the class that handles that client_type is loaded, and then return it. This lets you handle service providers with different behavior for different types of clients.

The base implementation just returns your class name.

If the programmer does not pass an explicit client_type the value that is passed in is default. So that should be mapped to a reasonable client type. This likely is something along the line of "webserver". That way your module can be used without specifying a client_type.

init

After new has figured out the right class to load, it immediately calls $self-e<gtinit($opts)> with $opts being a hashref of all options passed to LWP::Authen::OAuth2->new(...) that were not consumed in figuring out the service provider. This method can then extract any parameters that it wants to before anything else happens.

If you only want to require/allow a few parameters to be extracted into the service provider object, then there is no need to write your own init. But if you want additional logic depending on passed in parameters, you can.

To consume options and copy them to $self please use the following methods:

    $self->copy_option($opts, $required_field);
    $self->copy_option($opts, $optional_field, $default);

If you want to consume options and return them as values instead:

    my $value1 = $self->extract_option($opts, $required_field);
    my $value2 = $self->extract_option($opts, $optional_field, $default);

These methods delete from the hash, so do not try to consume an option twice.

required_init

The parameters that must be passed into LWP::Authen::OAuth2->new(...) to initialize the service provider object. The default required parameters are client_id and client_secret, which in turn get used as default arguments inside of methods that need them. In general it is good to only require arguments that are needed to generate refreshed tokens. If you will not get a refresh_token in your flow, then you should require nothing.

optional_init

The parameters that can be passed into LWP::Authen::OAuth2->new(...) to initialize the service provider object. The default optional parameters are redirect_uri and scope which, if passed, do not have to be passed into other method calls.

The state is not included as an explicit hint that you should not simply use a default value.

Note that these lists are deduped, so there is no harm in parameters being both required and optional, or appearing multiple times.

{authorization,request,refresh}_required_params

These three methods list parameters that must be included in the authorization url, the post to request tokens, and the post to refresh tokens respectively. If you explicitly provide these lists of required parameters, and a user fails to provide one (or more) of the parameters, the generated error message can tell the user which parameters are missing.

{authorization,request,refresh}_optional_params

These three methods list parameters that can be included in the authorization url, the post to request tokens, and the post to refresh tokens respectively. In strict mode, supplying any parameters not included in more or required params will be an error. Otherwise this has little effect.

{authorization,request,refresh}_default_params

These three methods returns a list of key/value pairs mapping parameters to default values in the authorization url, the post to request tokens, and the post to get refreshed tokens respectively. Supplying these can stop people from having to supply the parameters themselves.

An example where this could be useful is to support a flow that uses different types of requests than normal. For example with some client types and service providers, you might use a type of request with a grant_type of password or client_credentials.

post_to_token_endpoint

When a post to a token endpoint is constructed, this actually sends the request. The specification allows service providers to require authentication beyond what the specification requires, which may require cookies, specific headers, etc. This method allows you to address that case.

access_token_class

Given a token_type, what class implements access tokens of that type? If your provider creates a new token type, or implements an existing token type in a quirky way that requires a nonstandard model to handle, this method can let you add support for that.

The specification says that all the token_type must be case insensitive, so all types are lower cased for you.

If the return value does not look like a package name, it is assumed to be an error message. As long as you have spaces in your error messages and normal looking class names, this should DWIM.

See LWP::Authen::OAuth2::AccessToken for a description of the interface that your access token class needs to meet. (You do not have to subclass that - just duck typing here.)

oauth2_class

Override this to cause LWP::Authen::OAuth2->new(...) to return an object in a custom class. This would be appropriate if people using your service provider need methods exposed that are not in LWP::Authen::OAuth2.

Few service provider classes should find a reason to do this, but it can be done if you need.

collect_action_params

This is the method that processes parameters for a given action. Should your service provider support a new kind of request, you can use this along with the *_{required,more,default}_params functions to support it.

The implementation of request_tokens in this module give an example of how to use it.

CONTRIBUTING

Patches contributing new service provider subclasses to this distributions are encouraged. Should you wish to do so, please submit a git pull request that does the following:

Implement your provider

The more completely implemented, the better.

Name it properly

The name should be of the form:

    LWP::Authen::OAuth2::ServiceProvider::$ServiceProvider

List it

It needs to be listed as a known service provider in this module.

Test it

It is impossible to usefully test a service provider module without client secrets. However you can have public tests that it compiles, and private tests that will, if someone supplies the necessary secrets, run fuller tests that all works. See the existing unit tests for examples.

Include it

Your files need to be included in the MANIFEST in the root directory.

Document Client Registration

A developer should be able to read your module and know how to register themselves as a client of the service provider.

List Client Types

Please list the client types that the service provider uses, with just enough detail that a developer can figure out which one to use. Listed types should, of course, either be implemented or be documented as not implemented.

Document important quirks

If the service provider requires or allows useful parameters, try to mention them in your documentation.

Document limitations

If there are known limitations in your implementation, please state them.

Link to official documentation

If the service provider provides official OAuth 2 documentation, please link to it. Ideally a developer will not need to refer to it, but should know how to find it.

AUTHORS

• Ben Tilly, <btilly at gmail.com>

• Thomas Klausner <domm@plix.at>

COPYRIGHT AND LICENSE

This software is copyright (c) 2013 - 2022 by Ben Tilly, Rent.com, Thomas Klausner.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.