Dancer2::Plugin::Github::Auth

dancer2_plugin_gh_auth.pl

package Dancer2::Plugin::Auth::Github;

use strict;
use warnings FATAL => 'all';
use Carp 'croak';

use Dancer2;
use Dancer2::Plugin;

use Digest::SHA qw(sha256_hex);
use LWP::UserAgent;
use JSON qw(decode_json);

our $VERSION = '0.01';

my $client_id;
my $client_secret;
my $scope = "";
my $github_redirect_url = 'https://github.com/login/oauth/authorize/';
my $github_post_url = 'https://github.com/login/oauth/access_token/';
my $github_auth_failed = '/auth/github/failed';
my $github_auth_success = '/';
my $state_salt = "RandomSalt";

#dancer2 stuff.


#A method to initialize everything
register 'auth_github_init' => sub {
  warn "auth github loaded";
    my $dsl = shift;
    
	my $config = plugin_setting;
	
	$client_id 		  = $config->{client_id};
    $client_secret    = $config->{client_secret};
    	
	for my $param (qw/client_id client_secret/) {
        croak "$param is expected but not found in configuration" 
            unless $config->{$param};
    }
	#sthe following configs are optional.
 	if($config->{scope}) 
    {
		$scope = $config->{scope};
	}
	#these configs have default values.
	if($config->{github_auth_failed})
	{
		$github_auth_failed = $config->{github_auth_failed};
	}
	if($config->{github_auth_success})
	{
		$github_auth_success = $config->{github_auth_success};
	}
	#$dsl->debug 'Loaded config..';
    
    #registers this as a callback url
    $dsl->app->add_route(
	    regexp => '/auth/github/callback',
	    code => sub {
		my $generate_state = sha256_hex($client_id.$client_secret.$state_salt);
		my $state_received = $dsl->params->{'state'};
		if($state_received eq $generate_state) { 
			warn("State received correctly.");
		    my $code                   = $dsl->params->{'code'};
		    my $browser                = LWP::UserAgent->new;
		    my $resp                   = $browser->post($github_post_url,
		    [
		    	client_id                  => $client_id,
			    client_secret              => $client_secret, 
			    code                       => $code,
			    state                      => $state_received
		    ]);
		    die "error while fetching: ", $resp->status_line
		    unless $resp->is_success;
		    
		    my %querystr = parse_query_str($resp->decoded_content);
		    my $acc = $querystr{access_token};
		    warn "got access token? $acc";
		
		    if($acc) {
				my $jresp  = $browser->get("https://api.github.com/user?access_token=$acc");
				my $json = decode_json($jresp->decoded_content);
				warn("setting session");
				$dsl->session(github_user =>  $json);
				warn Data::Dumper::Dumper($dsl->app->session('github_user'));
				$dsl->session(github_access_token => $acc);
				#session 'logged_in' => true;
				warn("before redirect");
				$dsl->redirect($github_auth_success);
				return;
		    } 
		}
		$dsl->redirect($github_auth_failed);
	    },
	method => 'get');
};
#returns the url you need to redirect to to authenticate on github
register 'auth_github_authenticate_url'  => sub {
	my $generate_state = sha256_hex($client_id.$client_secret.$state_salt);
	return "$github_redirect_url?&client_id=$client_id&scope=$scope&state=$generate_state";
};

#helper method to parse query string.
sub parse_query_str {
	my $str = shift;
	my %in = ();
	if (length ($str) > 0){
	      my $buffer = $str;
	      my @pairs = split(/&/, $buffer);
	      foreach my $pair (@pairs){
	           my ($name, $value) = split(/=/, $pair);
	           $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
	           $in{$name} = $value; 
	      }
	 }
	return %in;
}
register_plugin;

1; # End of Dancer::Plugin::Auth::Github