LWP::Authen::OAuth2(3) Make requests to OAuth2 APIs.

VERSION

Version 0.10

SYNOPSIS

OAuth 2 is a protocol that lets a user tell a service provider that a consumer has permission to use the service provider's APIs to do things that require access to the user's account. This module tries to make life easier for someone who wants to write a consumer in Perl.

Specifically it provides convenience methods for all of the requests that are made to the service provider as part of the permission handshake, and after that will proxy off of LWP::UserAgent to let you send properly authenticated requests to the API that you are trying to use. When possible, this will include transparent refresh/retry logic for access tokens expiration.

For a full explanation of OAuth 2, common terminology, the requests that get made, and the necessary tasks that this module does not address, please see LWP::Authen::OAuth2::Overview

This module will not help with OAuth 1. See the similarly named but unrelated LWP::Authen::OAuth for a module that can help with that.

Currently LWP::Authen::OAuth2 provides ready-to-use classes to use OAuth2 with

You can also access any other OAuth2 service by setting up a plain "LWP::Authen::OAuth2" object. If you do, and the service provider might be of interest to other people, please submit a patch so we can include it in this distribution, or release it as a standalone package.

Here are examples of simple usage.


use LWP::Authen::OAuth2;
# Constructor
my $oauth2 = LWP::Authen::OAuth2->new(
client_id => "Public from service provider",
client_secret => "s3cr3t fr0m svc prov",
service_provider => "Google",
redirect_uri => "https://your.url.com/",
# Optional hook, but recommended.
save_tokens => \&save_tokens,
save_tokens_args => [ $dbh ],
# This is for when you have tokens from last time.
token_string => $token_string.
);
# URL for user to go to to start the process.
my $url = $oauth2->authorization_url();
# The authorization_url sends the user to the service provider to
# say that you want to be authorized. After the user confirms that
# request, the service provider sends the user back to you with a
# code. This might be a CGI parameter, something that the user is
# supposed to paste to you - that's between you and the service
# provider.
# Assuming that you have your code, get your tokens from the service
# provider.
$oauth2->request_tokens(code => $code);
# Get your token as a string you can easily store, pass around, etc.
# If you have a save_tokens callback, that gets passed this string
# whenever the tokens change.
#
# This string bears a suspicious resemblance to serialized JSON.
my $token_string = $oauth2->token_string,
# Access the API. Consult the service_provider's documentation for when
# to use which type of request. Note that argument processing is the
# same as in LWP. Thus the parameters array and headers hash are both
# optional.
$oauth2->get($url, %header);
$oauth2->post($url, \@parameters, %header);
$oauth2->put($url, %header);
$oauth2->delete($url, %header);
$oauth2->head($url, %header);
# And if you need more flexibility, you can use LWP::UserAgent's request
# method
$oauth2->request($http_request, $content_file);
# In some flows you can refresh tokens, in others you have to go through
# the handshake yourself. This method lets you know whether a refresh
# looks possible.
$oauth2->can_refresh_tokens();
# This method lets you know when it is time to reauthorize so that you
# can find out in a nicer way than failing an API call.
$oauth2->should_refresh();

CONSTRUCTOR

When you call "LWP::Authen::OAuth2->new(...)", arguments are passed as a key/value list. They are processed in the following phases:
Construct service provider
Service provider collects arguments it wants
LWP::Authen::OAuth2 overrides defaults from arguments
Sanity check

Here are those phases in more detail.

Construct service provider
There are two ways to construct a service provider.
Prebuilt class
To load a prebuilt class you just need one or two arguments.
"service_provider => $Foo,"
In the above construct, $Foo identifies the base class for your service provider. The actual class will be the first of the following two classes that can be loaded. Failure to find either is an error. 

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

A list of prebuilt service provider classes is in LWP::Authen::OAuth2::ServiceProvider as well as instructions for making a new one.

"client_type => $name_of_client_type"
Some service providers will keep track of your client type (``webserver'' application, ``installed'' application, etc), and will treat them differently. A base service provider class can choose to accept a "client_type" parameter to let it know what to expect.

Whether this is done, and the allowable values, are up to the service provider class.

Built on the fly
The behavior of simple service providers can be described on the fly without needing a prebuilt class. To do that, the following arguments can be filled with arguments from your service provider:
"authorization_endpoint => $auth_url,"
This is the URL which the user is directed to in the authorization request.
"token_endpoint => $token_url,"
This is the URL which the consumer goes to for tokens.
Various optional fields
LWP::Authen::OAuth2::ServiceProvider documents many methods that are available to customize the actual requests made, and defaults available. Simple service providers can likely get by without this, but here is a list of those methods that can be specified instead in the constructor: 

    # Arrayrefs
    required_init
    optional_init
    authorization_required_params
    authorization_optional_params
    request_required_params
    request_optional_params
    refresh_required_params
    refresh_optional_params
    # Hashrefs
    authorization_default_params
    request_default_params
    refresh_default_params
Service provider collects arguments it wants
In general, arguments passed into the constructor do not have to be passed into individual method calls. Furthermore in order to be able to do the automatic token refresh for you, the constructor must include the arguments that will be required.

By default you are required to pass your "client_id" and "client_secret". And optionally can pass a "redirect_uri" and "scope". (The omission of "state" is a deliberate hint that if you use that field, you should be generating random values on the fly. And not trying to go to some reasonable default.)

However what is required is up to the service provider.

LWP::Authen::OAuth2 overrides defaults from arguments
The following defaults are available to be overridden in the constructor, or can be overridden later. In the unlikely event that there is a conflict with the service provider's arguments, these will have to be overridden later.
"error_handler => \&error_handler,"
Specifies the function that will be called when errors happen. The default is "Carp::croak".
"is_strict => $bool,"
Is strict mode on? If it is, then excess parameters to requests that are part of the authorization process will trigger errors. If it is not, then excess arguments are passed to the service provider as is, who according to the specification is supposed to ignore them.

Strict mode is the default.

"early_refresh_time => $seconds,"
How many seconds before the end of estimated access token expiration you will have "should_refresh" start returning true.
"prerefresh => \&prerefresh,"
A handler to be called before attempting to refresh tokens. It is passed the $oauth2 object. If it returns a token string, that will be used to generate tokens instead of going to the service provider.

The purpose of this hook is so that, even if you have multiple processes accessing an API simultaneously, only one of them will try to refresh tokens with the service provider. (Service providers may dislike having multiple refresh requests arrive at once from the same consumer for the same user.)

By default this is not provided.

"save_tokens => \&save_tokens,"
Whenever tokens are returned from the service provider, this callback will receive a token string that can be stored and then retrieved in another process that needs to construct a $oauth2 object.

By default this is not provided. However if you intend to access the API multiple times from multiple processes, it is recommended.

"save_tokens_args => [ args ],"
Additional arguments passed to the save_tokens callback function after the token string. This can be used to pass things like database handles or other data to the callback along with the token string. Provide a reference to an array of arguments in the constructure. When the callback is called the arguments are passed to the callback as an array, so in the example below $arg1 will be ``foo'' and $arg2 will be ``bar'' 

    ...
    save_tokens => \&save_tokens,
    save_tokens_args => [ "foo", "bar" ],
    ...
    sub save_tokens {
        my ($token_string, $arg1, $arg2) = @_;
        ...
    }
"token_string => $token_string,"
Supply tokens generated in a previous request so that you don't have to ask the service provider for new ones. Some service providers refuse to hand out tokens too quickly, so this can be important.
"user_agent => $ua,"
What user agent gets used under the hood? Defaults to a new lWP::UserAgent created on the fly.
Sanity check
Any arguments that are left over are assumed to be mistakes and a fatal warning is generated.

METHODS

Once you have an object, the following methods may be useful for writing a consumer.

$oauth2->authorization_url(%opts)

Generate a URL for the user to go to to request permissions. By default the "response_type" and "client_id" are defaulted, and all of "redirect_uri", "state" and "scope" are optional but not required. However in practice this all varies by service provider and client type, so look for documentation on that for the actual list that you need.

$oauth2->request_tokens(%opts)

Request tokens from the service provider (if possible). By default the "grant_type", "client_id" and "client_secret" are defaulted, and the "scope" is required. However in practice this all varies by service provider and client type, so look for documentation on that for the actual list that you need.

$oauth2->get(...)

Issue a "get" request to an OAuth 2 protected URL, just like you would using LWP::UserAgent to a normal URL.

$oauth2->head(...)

Issue a "head" request to an OAuth 2 protected URL, just like you would using LWP::UserAgent to a normal URL.

$oauth2->post(...)

Issue a "post" request to an OAuth 2 protected URL, just like you would using LWP::UserAgent to a normal URL.

$oauth2->delete(...)

Issue a "delete" request to an OAuth 2 protected URL, similar to the previous examples. (This shortcut is not by default available with LWP::UserAgent.)

$oauth2->put(...)

Issue a "put" request to an OAuth 2 protected URL, similar to the previous examples. (This shortcut is not by default available with LWP::UserAgent.)

$oauth2->request(...)

Issue any "request" that you could issue with LWP::UserAgent, except that it will be properly signed to go to an OAuth 2 protected URL.

$oauth2->can_refresh_tokens

Is sufficient information available to try to refresh tokens?

$oauth2->should_refresh()

Is it time to refresh tokens?

$oauth2->set_early_refresh_time($seconds)

Set how many seconds before the end of token expiration the method "should_refresh" will start turning true. Values over half the initial expiration time of access tokens will be ignored to avoid refreshing too often. This defaults to 300.

$oauth2->set_is_strict($mode)

Set strict mode on/off. See the discussion of "is_strict" in the constructor for an explanation of what it does.

$oauth2->set_error_handler(\&error_handler)

Set the error handler. See the discussion of "error_handler" in the constructor for an explanation of what it does.

$oauth2->set_prerefresh(\&prerefresh)

Set the prerefresh handler. See the discussion of "prerefresh_handler" in the constructor for an explanation of what it does.

$oauth2->set_save_tokens($ua)

Set the save tokens handler. See the discussion of "save_tokens" in the constructor for an explanation of what it does.

$oauth2->set_user_agent($ua)

Set the user agent. This should respond to the same methods that a LWP::UserAgent responds to.

$oauth2->user_agent()

Get the user agent. The default if none was explicitly set is a new LWP::UserAgent object.

AUTHOR

Ben Tilly, "<btilly at gmail.com>"

currently maintained by Thomas Klausner, "<[email protected]>"

Contributors

BUGS

Please report any bugs or feature requests to "bug-lwp-authen-oauth2 at rt.cpan.org", or through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=LWP-Authen-OAuth2>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command. 

    perldoc LWP::Authen::OAuth2

You can also look for information at:

Github (submit patches here)
<https://github.com/btilly/perl-oauth2>
RT: CPAN's request tracker (report bugs here)
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=LWP-Authen-OAuth2>
AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/LWP-Authen-OAuth2>
CPAN Ratings
<http://cpanratings.perl.org/d/LWP-Authen-OAuth2>
Search CPAN
<http://search.cpan.org/dist/LWP-Authen-OAuth2/>

ACKNOWLEDGEMENTS

Thanks to Rent.com <http://www.rent.com> for their generous support in letting me develop and release this module. My thanks also to Nick Wellnhofer <[email protected]> for Net::Google::Analytics::OAuth2 which was very enlightening while I was trying to figure out the details of how to connect to Google with OAuth2.

Thanks to

LICENSE AND COPYRIGHT

Copyright 2013 Rent.com.

This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:

<http://www.perlfoundation.org/artistic_license_2_0>

Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made by someone other than you, you are nevertheless required to ensure that your Modified Version complies with the requirements of this license.

This license does not grant you the right to use any trademark, service mark, tradename, or logo of the Copyright Holder.

This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed.

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