fulcrm_uuid/fulcrm_uuid.module

<?php /* -*- php -*- */

function fulcrm_uuid_stir_mt_srand() {
    if ( function_exists( 'drupal_random_bytes' ) )
        mt_srand( crc32( drupal_random_bytes( 4 ) ) );
    else if ( function_exists( 'microtime' ) )
        mt_srand( crc32( microtime() ) );
    else {
        $e1 = variable_get( 'fulcrm_uuid_entropy_1', '' );
        mt_srand( crc32( $e1 ) );
    }
}

function fulcrm_uuid_stir_entropy() {
    fulcrm_uuid_stir_mt_srand();

    $entropy = '';

    if ( function_exists( 'drupal_random_bytes' ) ) {
        $entropy .= drupal_random_bytes( 32 );
    } else {
        $entropy .= mt_rand();
        $entropy .= rand();

        $entropy .= time();
        if ( function_exists( 'microtime' ) )
            $entropy .= microtime();

        $entropy .= variable_get( 'cron_key', '' );
        $entropy .= variable_get( 'cron_last', '' );
        $entropy .= variable_get( 'drupal_private_key', '' );
        $entropy .= variable_get( 'site_name', '' );

        if ( function_exists( 'openssl_random_pseudo_bytes' ) )
            $entropy .= openssl_random_pseudo_bytes( 32 );

        $handle = fopen( '/dev/urandom', 'r' );
        $entropy .= fread( $handle, 32 );
        fclose( $handle );
    }

    $old_entropy = ( variable_get( 'fulcrm_uuid_entropy_1', '' ) .
                     variable_get( 'fulcrm_uuid_entropy_2', '' ) );
    variable_set( 'fulcrm_uuid_entropy_1', sha1( $entropy ) );
    variable_set( 'fulcrm_uuid_entropy_2', md5( $old_entropy . $entropy ) );

    fulcrm_uuid_stir_mt_srand();
}

function fulcrm_uuid_cron() {
    fulcrm_uuid_stir_entropy();
}

function fulcrm_uuid_uuid4() {
    static $data = '';

    if ( function_exists( 'drupal_random_bytes' ) )
        $data = $data . drupal_random_bytes( 4 );
    else
        $data = $data . uniqid( $more_entropy = true );

    $data = ( variable_get( 'fulcrm_uuid_entropy_2', '' ) .
              $data .
              variable_get( 'fulcrm_uuid_entropy_2', '' ) );

    $data = md5( $data );
    $rdata = hex2bin( $data );
    $rdata[ 6 ] = chr( ord( $rdata[ 6 ] ) & 0x0f | 0x40 );
    $rdata[ 8 ] = chr( ord( $rdata[ 8 ] ) & 0x3f | 0x80 );
    return vsprintf( '%s%s-%s-%s-%s-%s%s%s', str_split( bin2hex( $rdata ), 4 ) );
}