Re: Obtaining OAuth2 Access Token

Here is a bit more meat on the question with a working Twitter example:

I have a simple working system - written a long time ago so go easy on my code! - that allows any Twitter user to see who they follow and who follows them back and follow/unfollow them from that list. You can see this on my website and it demonstrates the workflow for OAuth2 albeit using Net::Twitter to do the connection work.

Here is the code that does the work with Twitter taken from the live site:

#!/usr/bin/perl

use cPanelUserConfig;
use Net::Twitter;
use Data::Dumper;
use JSON;
use POSIX qw(strftime);

require "incl/common.pl";
require "incl/html.pl";

$page_size    = 140;
$login_days    = 10;

my $twitter=Net::Twitter->new(     
    traits                => ['API::RESTv1_1'],
    consumer_key        => 'xxxxxxxxxx',
    consumer_secret     => 'xxxxxxxxxxxxxxxxxxxx',
    callback            => "https://$ENV{'SERVER_NAME'}/cgi-bin/twitte
+r.pl?command=authorize",
    ssl                    => 1,
    source                => 'BodBot',
);

if ($cookie{'Twitter_tok'} and $cookie{'Twitter_sec'}) {
    $twitter->access_token($cookie{'Twitter_tok'});
    $twitter->access_token_secret($cookie{'Twitter_sec'});
}

# Code to start the authorisation process
sub twitter {    
    $auth_url=$twitter->get_authorization_url(callback => "http://$ENV
+{'SERVER_NAME'}/cgi-bin/twitter.pl?command=authorize");
    print "Location: $auth_url\n\n";
    exit 0;
}

# Callback from Twitter
sub authorize {
    eval{($access_token, $access_token_secret, $user_id, $screen_name)
+=$twitter->request_access_token(token => $data{'oauth_token'}, token_
+secret => 'xxxxxxxxxxxxxxxxxxxx', verifier => $data{'oauth_verifier'}
+);};
    if ($@) {
        print "content-type: text/plain\n\n";
        print "ERROR:\n$@\n";
        exit 1;
    }
    &log("Access token obtained for \@$screen_name");
    $twitter->access_token($access_token);
    $twitter->access_token_secret($access_token_secret);
    $expiry="; expires=".(strftime "%a, %d-%b-%Y %H:%M:%S",(gmtime(tim
+e() + $login_days*24*3600)))." GMT";
    print "Set-cookie: Twitter_tok=$access_token; path=/; expires=$exp
+iry\n";
    print "Set-cookie: Twitter_sec=$access_token_secret; path=/; expir
+es=$expiry\n";
    print "Location: http://$ENV{'SERVER_NAME'}/cgi-bin/twitter.pl\n\n
+";
    exit 0;
}

# Logout and interact with Twitter
sub logout {
    print "Set-cookie: Twitter_tok=xxx; path=/; expires=Thu, 01-Jan-19
+70 00:00:01 GMT\n";
    print "Set-cookie: Twitter_sec=xxx; path=/; expires=Thu, 01-Jan-19
+70 00:00:01 GMT\n";
    print "Location: http://$ENV{'SERVER_NAME'}/cgi-bin/twitter.pl\n\n
+";
    exit 0;
}
    

sub XHRfollow {
    $result=$twitter->create_friend({ user_id => $data{'user'} });
    exit 0;
}


sub XHRunfollow {
    $result=$twitter->destroy_friend({ user_id => $data{'user'} });
    exit 0;
}
[download]

That shows an OAuth2 workflow that functions as it should.

For LinkedIn the general arrangement should work the same. Except that LinkedIn only passes back a code parameter - it doesn't pass back oauth_token or oauth_verifier. Instead the error is Token endpoint missing expected token_type in successful response. with a payload of:

{
    "serviceErrorCode": 65604,
    "message":          "Empty oauth2 access token",
    "status":           401
}
[download]

The LinkedIn API documentation doesn't seem very helpful to me.

Here is what I am trying...you can see this working on my test website. This runs exactly this code but with real keys. The callback URL is authorised to be used within LinkedIn.

#!/usr/bin/perl

use CGI::Carp qw(fatalsToBrowser);

use cPanelUserConfig;
use LWP::Authen::OAuth2;
use Data::Dumper;

use strict;
use warnings;

our %data;
require "incl/common.pl";

my $linkedin = LWP::Authen::OAuth2->new(
    client_id                => 'xxxxxxxxxx',
    client_secret            => 'xxxxxxxxxx',
    authorization_endpoint    => 'https://api.linkedin.com/uas/oauth2/
+authorization',
    token_endpoint             => 'https://api.linkedin.com/v2/accessT
+oken',
    redirect_uri            => "https://$ENV{'HTTP_HOST'}/cgi-bin/link
+edin.pl?command=authorize_linkedin",
    scope                    => 'w_member_social',
);

if ($data{'command'} eq 'linkedin') {
    my $auth_url = $linkedin->authorization_url;
    print "Location: $auth_url\n\n";
    exit 0;
}

if ($data{'command'} eq 'authorize_linkedin') {
    print "Content-type: text-plain\n\n";
    my $token = $linkedin->request_tokens(
        code        => $data{'code'},
    );
    print "TOKEN: $token\n";
}

print<<"END_HTML";
Content-type: text/html

<html>
<body>
<input type="button" value="LinkedIn" onClick="document.location.href=
+'?command=linkedin';">
</body>
</html>
END_HTML
[download]

The require just populates %data with the key/value pairs from the query string.

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