OATHAuthKey.php

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<?php
class OATHAuthKey {
    const MAIN_TOKEN = 1;
 
    const SCRATCH_TOKEN = -1;
 
    private $secret;
 
    private $scratchTokens;
 
    public static function newFromRandom() {
        $object = new self(
            Base32::encode( random_bytes( 10 ) ),
            []
        );
 
        $object->regenerateScratchTokens();
 
        return $object;
    }
 
    public function __construct( $secret, array $scratchTokens ) {
        // Currently harcoded values; might be used in future
        $this->secret = [
            'mode' => 'hotp',
            'secret' => $secret,
            'period' => 30,
            'algorithm' => 'SHA1',
        ];
        $this->scratchTokens = $scratchTokens;
    }
 
    public function getSecret() {
        return $this->secret['secret'];
    }
 
    public function getScratchTokens() {
        return $this->scratchTokens;
    }
 
    public function verifyToken( $token, OATHUser $user ) {
        global $wgOATHAuthWindowRadius;
 
        if ( $this->secret['mode'] !== 'hotp' ) {
            throw new \DomainException( 'OATHAuth extension does not support non-HOTP tokens' );
        }
 
        // Prevent replay attacks
        $memc = ObjectCache::newAnything( [] );
        $uid = CentralIdLookup::factory()->centralIdFromLocalUser( $user->getUser() );
        $memcKey = wfMemcKey( 'oathauth', 'usedtokens', $uid );
        $lastWindow = (int)$memc->get( $memcKey );
 
        $retval = false;
        $results = HOTP::generateByTimeWindow(
            Base32::decode( $this->secret['secret'] ),
            $this->secret['period'], -$wgOATHAuthWindowRadius, $wgOATHAuthWindowRadius
        );
 
        // Remove any whitespace from the received token, which can be an intended group seperator
        // or trimmeable whitespace
        $token = preg_replace( '/\s+/', '', $token );
 
        // Check to see if the user's given token is in the list of tokens generated
        // for the time window.
        foreach ( $results as $window => $result ) {
            if ( $window > $lastWindow && $result->toHOTP( 6 ) === $token ) {
                $lastWindow = $window;
                $retval = self::MAIN_TOKEN;
                break;
            }
        }
 
        // See if the user is using a scratch token
        if ( !$retval ) {
            $length = count( $this->scratchTokens );
            // Detect condition where all scratch tokens have been used
            if ( $length == 1 && "" === $this->scratchTokens[0] ) {
                $retval = false;
            } else {
                for ( $i = 0; $i < $length; $i++ ) {
                    if ( $token === $this->scratchTokens[$i] ) {
                        // If there is a scratch token, remove it from the scratch token list
                        unset( $this->scratchTokens[$i] );
                        $oathrepo = OATHAuthHooks::getOATHUserRepository();
                        $user->setKey( $this );
                        $oathrepo->persist( $user );
                        // Only return true if we removed it from the database
                        $retval = self::SCRATCH_TOKEN;
                        break;
                    }
                }
            }
        }
 
        if ( $retval ) {
            $memc->set(
                $memcKey,
                $lastWindow,
                $this->secret['period'] * ( 1 + 2 * $wgOATHAuthWindowRadius )
            );
        } else {
            // Increase rate limit counter for failed request
            $user->getUser()->pingLimiter( 'badoath' );
        }
 
        return $retval;
    }
 
    public function regenerateScratchTokens() {
        $scratchTokens = [];
        for ( $i = 0; $i < 5; $i++ ) {
            $scratchTokens[] = Base32::encode( random_bytes( 10 ) );
        }
        $this->scratchTokens = $scratchTokens;
    }
 
    public function isScratchToken( $token ) {
        $token = preg_replace( '/\s+/', '', $token );
        return in_array( $token, $this->scratchTokens, true );
    }
}