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MDL-61038 setuplib: Fixed PECL UUID extension support

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generate_uuid() has been refactored into \core\uuid::generate()
This commit is contained in:
Matteo Scaramuccia 2019-06-08 22:35:37 +02:00
parent f3507273e9
commit c7321899c9
5 changed files with 217 additions and 37 deletions
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2
lib/classes/lock/db_record_lock_factory.php
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@ -103,7 +103,7 @@ class db_record_lock_factory implements lock_factory {
* to duplicates in a clustered environment (especially on VMs due to poor time precision).
*/
protected function generate_unique_token() {
return generate_uuid();
return \core\uuid::generate();
}
/**

144
lib/classes/uuid.php Normal file
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@ -0,0 +1,144 @@
<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* V4 UUID generator.
*
* @package core
* @copyright 2019 Matteo Scaramuccia <moodle@matteoscaramuccia.com>
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core;
use Exception;
defined('MOODLE_INTERNAL') || die();
/**
* V4 UUID generator class.
*
* @package core
* @copyright 2019 Matteo Scaramuccia <moodle@matteoscaramuccia.com>
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class uuid {
/**
* Generate a V4 UUID using PECL UUID extension.
* @see https://github.com/php/pecl-networking-uuid PECL uuid
* @see https://tools.ietf.org/html/rfc4122
*
* @return string|bool The UUID when PECL UUID extension is available;
* otherwise, false.
*/
protected static function generate_uuid_via_pecl_uuid_extension() {
$uuid = false;
// Check if PECL uuid extension has been actually installed.
if (function_exists('\uuid_time')) {
// Set V4 version.
$uuid = \uuid_create(UUID_TYPE_RANDOM);
}
return $uuid;
}
/**
* Generate a V4 UUID using PHP 7+ features.
*
* @see https://www.php.net/manual/en/function.random-bytes.php
* @see https://tools.ietf.org/html/rfc4122
*
* @return string|bool The UUID when random_bytes() function is available;
* otherwise, false when missing the sources of randomness used by random_bytes().
*/
protected static function generate_uuid_via_random_bytes() {
$uuid = false;
// If none of the sources of randomness are available,
// then an Exception will be thrown.
try {
$data = random_bytes(16);
$data[6] = chr((ord($data[6]) & 0x0f) | 0x40); // Set version to 0100.
$data[8] = chr((ord($data[8]) & 0x3f) | 0x80); // Set bits 6-7 to 10.
$uuid = vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
} catch (Exception $e) {
// Could not generate a random string. Is this OS secure?
$uuid = false;
}
return $uuid;
}
/**
* Generate a V4 UUID.
*
* Unique is hard. Very hard. Attempt to use the PECL UUID function if available, and if not then revert to
* constructing the uuid using random_bytes or mt_rand.
*
* It is important that this token is not solely based on time as this could lead
* to duplicates in a clustered environment (especially on VMs due to poor time precision).
*
* UUIDs are just 128 bits long but with different supported versions (RFC 4122), mainly two:
* - V1: the goal is uniqueness, at the cost of anonymity since it is coupled to the host generating it, via its MAC address.
* - V4: the goal is randomness, at the cost of (rare) collisions.
* Here, the V4 type is the preferred choice.
*
* The format is:
* xxxxxxxx-xxxx-4xxx-Yxxx-xxxxxxxxxxxx
* where x is any hexadecimal digit and Y is a random choice from 8, 9, a, or b.
*
* @see https://tools.ietf.org/html/rfc4122
*
* @return string The V4 UUID.
*/
public static function generate() {
// Try PHP UUID extensions first.
$uuid = self::generate_uuid_via_pecl_uuid_extension();
// Fall back to better random features, when possible.
if (empty($uuid)) {
$uuid = self::generate_uuid_via_random_bytes();
}
// Finally, create it with the available randomness.
if (empty($uuid)) {
// Fallback uuid generation based on:
// "http://www.php.net/manual/en/function.uniqid.php#94959".
$uuid = sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
// 32 bits for "time_low".
mt_rand(0, 0xffff), mt_rand(0, 0xffff),
// 16 bits for "time_mid".
mt_rand(0, 0xffff),
// 16 bits for "time_hi_and_version",
// four most significant bits holds version number 4.
mt_rand(0, 0x0fff) | 0x4000,
// 16 bits, 8 bits for "clk_seq_hi_res",
// 8 bits for "clk_seq_low",
// two most significant bits holds zero and one for variant DCE1.1.
mt_rand(0, 0x3fff) | 0x8000,
// 48 bits for "node".
mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff));
}
return trim($uuid);
}
}

45
lib/setuplib.php
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@ -610,49 +610,24 @@ function get_exception_info($ex) {
}
/**
* Generate a uuid.
* Generate a V4 UUID.
*
* Unique is hard. Very hard. Attempt to use the PECL UUID functions if available, and if not then revert to
* Unique is hard. Very hard. Attempt to use the PECL UUID function if available, and if not then revert to
* constructing the uuid using mt_rand.
*
* It is important that this token is not solely based on time as this could lead
* to duplicates in a clustered environment (especially on VMs due to poor time precision).
*
* @see https://tools.ietf.org/html/rfc4122
*
* @deprecated since Moodle 3.8 MDL-61038 - please do not use this function any more.
* @see \core\uuid::generate()
*
* @return string The uuid.
*/
function generate_uuid() {
$uuid = '';
if (function_exists("uuid_create")) {
$context = null;
uuid_create($context);
uuid_make($context, UUID_MAKE_V4);
uuid_export($context, UUID_FMT_STR, $uuid);
} else {
// Fallback uuid generation based on:
// "http://www.php.net/manual/en/function.uniqid.php#94959".
$uuid = sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',
// 32 bits for "time_low".
mt_rand(0, 0xffff), mt_rand(0, 0xffff),
// 16 bits for "time_mid".
mt_rand(0, 0xffff),
// 16 bits for "time_hi_and_version",
// four most significant bits holds version number 4.
mt_rand(0, 0x0fff) | 0x4000,
// 16 bits, 8 bits for "clk_seq_hi_res",
// 8 bits for "clk_seq_low",
// two most significant bits holds zero and one for variant DCE1.1.
mt_rand(0, 0x3fff) | 0x8000,
// 48 bits for "node".
mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff));
}
return trim($uuid);
debugging('generate_uuid() is deprecated. Please use \core\uuid::generate() instead.', DEBUG_DEVELOPER);
return \core\uuid::generate();
}
/**
@ -1513,7 +1488,7 @@ function make_unique_writable_directory($basedir, $exceptiononerror = true) {
do {
// Generate a new (hopefully unique) directory name.
$uniquedir = $basedir . DIRECTORY_SEPARATOR . generate_uuid();
$uniquedir = $basedir . DIRECTORY_SEPARATOR . \core\uuid::generate();
} while (
// Ensure that basedir is still writable - if we do not check, we could get stuck in a loop here.
is_writable($basedir) &&

62
lib/tests/setuplib_test.php
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@ -25,7 +25,6 @@
defined('MOODLE_INTERNAL') || die();
/**
* Unit tests for setuplib.php
*
@ -476,4 +475,65 @@ class core_setuplib_testcase extends advanced_testcase {
public function test_get_real_size($input, $expectedbytes) {
$this->assertEquals($expectedbytes, get_real_size($input));
}
/**
* Validate the given V4 UUID.
*
* @param string $value The candidate V4 UUID
* @return bool True if valid; otherwise, false.
*/
protected static function is_valid_uuid_v4($value) {
// Version 4 UUIDs have the form xxxxxxxx-xxxx-4xxx-Yxxx-xxxxxxxxxxxx
// where x is any hexadecimal digit and Y is one of 8, 9, aA, or bB.
// First, the size is 36 (32 + 4 dashes).
if (strlen($value) != 36) {
return false;
}
// Finally, check the format.
$uuidv4pattern = '/^[0-9A-F]{8}-[0-9A-F]{4}-4[0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}$/i';
return (preg_match($uuidv4pattern, $value) === 1);
}
/**
* Test the \core\uuid::generate_uuid_via_pecl_uuid_extension() function.
*/
public function test_core_uuid_generate_uuid_via_pecl_uuid_extension() {
if (!extension_loaded('uuid')) {
$this->markTestSkipped("PHP 'uuid' extension not loaded.");
}
if (!function_exists('uuid_time')) {
$this->markTestSkipped("PHP PECL 'uuid' extension not loaded.");
}
// The \core\uuid::generate_uuid_via_pecl_uuid_extension static method is protected. Use Reflection to call the method.
$method = new ReflectionMethod('\core\uuid', 'generate_uuid_via_pecl_uuid_extension');
$method->setAccessible(true);
$uuid = $method->invoke(null);
$this->assertTrue(self::is_valid_uuid_v4($uuid), "Invalid v4 uuid: '$uuid'");
}
/**
* Test the \core\uuid::generate_uuid_via_random_bytes() function.
*/
public function test_core_uuid_generate_uuid_via_random_bytes() {
try {
random_bytes(1);
} catch (Exception $e) {
$this->markTestSkipped('No source of entropy for random_bytes. ' . $e->getMessage());
}
// The \core\uuid::generate_uuid_via_random_bytes static method is protected. Use Reflection to call the method.
$method = new ReflectionMethod('\core\uuid', 'generate_uuid_via_random_bytes');
$method->setAccessible(true);
$uuid = $method->invoke(null);
$this->assertTrue(self::is_valid_uuid_v4($uuid), "Invalid v4 uuid: '$uuid'");
}
/**
* Test the \core\uuid::generate() function.
*/
public function test_core_uuid_generate() {
$uuid = \core\uuid::generate();
$this->assertTrue(self::is_valid_uuid_v4($uuid), "Invalid v4 UUID: '$uuid'");
}
}

1
lib/upgrade.txt
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@ -3,6 +3,7 @@ information provided here is intended especially for developers.
=== 3.8 ===
* The yui checknet module is removed. Call \core\session\manager::keepalive instead.
* The generate_uuid() function has been deprecated. Please use \core\uuid::generate() instead.
=== 3.7 ===
* Nodes in the navigation api can have labels for each group. See set/get_collectionlabel().