lib/externallib.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17
  18 /**
  19  * Support for external API
  20  *
  21  * @package    core_webservice
  22  * @copyright  2009 Petr Skodak
  23  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24  */
  25
  26 defined('MOODLE_INTERNAL') || die();
  27
  28 /**
  29  * Exception indicating user is not allowed to use external function in the current context.
  30  *
  31  * @package    core_webservice
  32  * @copyright  2009 Petr Skodak
  33  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  34  * @since Moodle 2.0
  35  */
  36 class restricted_context_exception extends moodle_exception {
  37     /**
  38      * Constructor
  39      *
  40      * @since Moodle 2.0
  41      */
  42     function __construct() {
  43         parent::__construct('restrictedcontextexception', 'error');
  44     }
  45 }
  46
  47 /**
  48  * Base class for external api methods.
  49  *
  50  * @package    core_webservice
  51  * @copyright  2009 Petr Skodak
  52  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  53  * @since Moodle 2.0
  54  */
  55 class external_api {
  56
  57     /** @var stdClass context where the function calls will be restricted */
  58     private static $contextrestriction;
  59
  60     /**
  61      * Returns detailed function information
  62      *
  63      * @param string|object $function name of external function or record from external_function
  64      * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
  65      *                        MUST_EXIST means throw exception if no record or multiple records found
  66      * @return stdClass description or false if not found or exception thrown
  67      * @since Moodle 2.0
  68      */
  69     public static function external_function_info($function, $strictness=MUST_EXIST) {
  70         global $DB, $CFG;
  71
  72         if (!is_object($function)) {
  73             if (!$function = $DB->get_record('external_functions', array('name' => $function), '*', $strictness)) {
  74                 return false;
  75             }
  76         }
  77
  78         // First try class autoloading.
  79         if (!class_exists($function->classname)) {
  80             // Fallback to explicit include of externallib.php.
  81             if (empty($function->classpath)) {
  82                 $function->classpath = core_component::get_component_directory($function->component).'/externallib.php';
  83             } else {
  84                 $function->classpath = $CFG->dirroot.'/'.$function->classpath;
  85             }
  86             if (!file_exists($function->classpath)) {
  87                 throw new coding_exception('Cannot find file with external function implementation');
  88             }
  89             require_once($function->classpath);
  90             if (!class_exists($function->classname)) {
  91                 throw new coding_exception('Cannot find external class');
  92             }
  93         }
  94
  95         $function->ajax_method = $function->methodname.'_is_allowed_from_ajax';
  96         $function->parameters_method = $function->methodname.'_parameters';
  97         $function->returns_method    = $function->methodname.'_returns';
  98         $function->deprecated_method = $function->methodname.'_is_deprecated';
  99
 100         // Make sure the implementaion class is ok.
 101         if (!method_exists($function->classname, $function->methodname)) {
 102             throw new coding_exception('Missing implementation method of '.$function->classname.'::'.$function->methodname);
 103         }
 104         if (!method_exists($function->classname, $function->parameters_method)) {
 105             throw new coding_exception('Missing parameters description');
 106         }
 107         if (!method_exists($function->classname, $function->returns_method)) {
 108             throw new coding_exception('Missing returned values description');
 109         }
 110         if (method_exists($function->classname, $function->deprecated_method)) {
 111             if (call_user_func(array($function->classname, $function->deprecated_method)) === true) {
 112                 $function->deprecated = true;
 113             }
 114         }
 115         $function->allowed_from_ajax = false;
 116
 117         // Fetch the parameters description.
 118         $function->parameters_desc = call_user_func(array($function->classname, $function->parameters_method));
 119         if (!($function->parameters_desc instanceof external_function_parameters)) {
 120             throw new coding_exception('Invalid parameters description');
 121         }
 122
 123         // Fetch the return values description.
 124         $function->returns_desc = call_user_func(array($function->classname, $function->returns_method));
 125         // Null means void result or result is ignored.
 126         if (!is_null($function->returns_desc) and !($function->returns_desc instanceof external_description)) {
 127             throw new coding_exception('Invalid return description');
 128         }
 129
 130         // Now get the function description.
 131
 132         // TODO MDL-31115 use localised lang pack descriptions, it would be nice to have
 133         // easy to understand descriptions in admin UI,
 134         // on the other hand this is still a bit in a flux and we need to find some new naming
 135         // conventions for these descriptions in lang packs.
 136         $function->description = null;
 137         $servicesfile = core_component::get_component_directory($function->component).'/db/services.php';
 138         if (file_exists($servicesfile)) {
 139             $functions = null;
 140             include($servicesfile);
 141             if (isset($functions[$function->name]['description'])) {
 142                 $function->description = $functions[$function->name]['description'];
 143             }
 144             if (isset($functions[$function->name]['testclientpath'])) {
 145                 $function->testclientpath = $functions[$function->name]['testclientpath'];
 146             }
 147             if (isset($functions[$function->name]['type'])) {
 148                 $function->type = $functions[$function->name]['type'];
 149             }
 150             if (isset($functions[$function->name]['ajax'])) {
 151                 $function->allowed_from_ajax = $functions[$function->name]['ajax'];
 152             } else if (method_exists($function->classname, $function->ajax_method)) {
 153                 if (call_user_func(array($function->classname, $function->ajax_method)) === true) {
 154                     debugging('External function ' . $function->ajax_method . '() function is deprecated.' .
 155                               'Set ajax=>true in db/service.php instead.', DEBUG_DEVELOPER);
 156                     $function->allowed_from_ajax = true;
 157                 }
 158             }
 159             if (isset($functions[$function->name]['loginrequired'])) {
 160                 $function->loginrequired = $functions[$function->name]['loginrequired'];
 161             } else {
 162                 $function->loginrequired = true;
 163             }
 164         }
 165
 166         return $function;
 167     }
 168
 169     /**
 170      * Call an external function validating all params/returns correctly.
 171      *
 172      * Note that an external function may modify the state of the current page, so this wrapper
 173      * saves and restores tha PAGE and COURSE global variables before/after calling the external function.
 174      *
 175      * @param string $function A webservice function name.
 176      * @param array $args Params array (named params)
 177      * @param boolean $ajaxonly If true, an extra check will be peformed to see if ajax is required.
 178      * @return array containing keys for error (bool), exception and data.
 179      */
 180     public static function call_external_function($function, $args, $ajaxonly=false) {
 181         global $PAGE, $COURSE, $CFG, $SITE;
 182
 183         require_once($CFG->libdir . "/pagelib.php");
 184
 185         $externalfunctioninfo = self::external_function_info($function);
 186
 187         $currentpage = $PAGE;
 188         $currentcourse = $COURSE;
 189         $response = array();
 190
 191         try {
 192             // Taken straight from from setup.php.
 193             if (!empty($CFG->moodlepageclass)) {
 194                 if (!empty($CFG->moodlepageclassfile)) {
 195                     require_once($CFG->moodlepageclassfile);
 196                 }
 197                 $classname = $CFG->moodlepageclass;
 198             } else {
 199                 $classname = 'moodle_page';
 200             }
 201             $PAGE = new $classname();
 202             $COURSE = clone($SITE);
 203
 204             if ($ajaxonly && !$externalfunctioninfo->allowed_from_ajax) {
 205                 throw new moodle_exception('servicenotavailable', 'webservice');
 206             }
 207
 208             // Do not allow access to write or delete webservices as a public user.
 209             if ($externalfunctioninfo->loginrequired) {
 210                 if (defined('NO_MOODLE_COOKIES') && NO_MOODLE_COOKIES && !PHPUNIT_TEST) {
 211                     throw new moodle_exception('servicenotavailable', 'webservice');
 212                 }
 213                 if (!isloggedin()) {
 214                     throw new moodle_exception('servicenotavailable', 'webservice');
 215                 } else {
 216                     require_sesskey();
 217                 }
 218             }
 219
 220             // Validate params, this also sorts the params properly, we need the correct order in the next part.
 221             $callable = array($externalfunctioninfo->classname, 'validate_parameters');
 222             $params = call_user_func($callable,
 223                                      $externalfunctioninfo->parameters_desc,
 224                                      $args);
 225
 226             // Execute - gulp!
 227             $callable = array($externalfunctioninfo->classname, $externalfunctioninfo->methodname);
 228             $result = call_user_func_array($callable,
 229                                            array_values($params));
 230
 231             // Validate the return parameters.
 232             if ($externalfunctioninfo->returns_desc !== null) {
 233                 $callable = array($externalfunctioninfo->classname, 'clean_returnvalue');
 234                 $result = call_user_func($callable, $externalfunctioninfo->returns_desc, $result);
 235             }
 236
 237             $response['error'] = false;
 238             $response['data'] = $result;
 239         } catch (Exception $e) {
 240             $exception = get_exception_info($e);
 241             unset($exception->a);
 242             $exception->backtrace = format_backtrace($exception->backtrace, true);
 243             if (!debugging('', DEBUG_DEVELOPER)) {
 244                 unset($exception->debuginfo);
 245                 unset($exception->backtrace);
 246             }
 247             $response['error'] = true;
 248             $response['exception'] = $exception;
 249             // Do not process the remaining requests.
 250         }
 251
 252         $PAGE = $currentpage;
 253         $COURSE = $currentcourse;
 254
 255         return $response;
 256     }
 257
 258     /**
 259      * Set context restriction for all following subsequent function calls.
 260      *
 261      * @param stdClass $context the context restriction
 262      * @since Moodle 2.0
 263      */
 264     public static function set_context_restriction($context) {
 265         self::$contextrestriction = $context;
 266     }
 267
 268     /**
 269      * This method has to be called before every operation
 270      * that takes a longer time to finish!
 271      *
 272      * @param int $seconds max expected time the next operation needs
 273      * @since Moodle 2.0
 274      */
 275     public static function set_timeout($seconds=360) {
 276         $seconds = ($seconds < 300) ? 300 : $seconds;
 277         core_php_time_limit::raise($seconds);
 278     }
 279
 280     /**
 281      * Validates submitted function parameters, if anything is incorrect
 282      * invalid_parameter_exception is thrown.
 283      * This is a simple recursive method which is intended to be called from
 284      * each implementation method of external API.
 285      *
 286      * @param external_description $description description of parameters
 287      * @param mixed $params the actual parameters
 288      * @return mixed params with added defaults for optional items, invalid_parameters_exception thrown if any problem found
 289      * @since Moodle 2.0
 290      */
 291     public static function validate_parameters(external_description $description, $params) {
 292         if ($description instanceof external_value) {
 293             if (is_array($params) or is_object($params)) {
 294                 throw new invalid_parameter_exception('Scalar type expected, array or object received.');
 295             }
 296
 297             if ($description->type == PARAM_BOOL) {
 298                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 299                 if (is_bool($params) or $params === 0 or $params === 1 or $params === '0' or $params === '1') {
 300                     return (bool)$params;
 301                 }
 302             }
 303             $debuginfo = 'Invalid external api parameter: the value is "' . $params .
 304                     '", the server was expecting "' . $description->type . '" type';
 305             return validate_param($params, $description->type, $description->allownull, $debuginfo);
 306
 307         } else if ($description instanceof external_single_structure) {
 308             if (!is_array($params)) {
 309                 throw new invalid_parameter_exception('Only arrays accepted. The bad value is: \''
 310                         . print_r($params, true) . '\'');
 311             }
 312             $result = array();
 313             foreach ($description->keys as $key=>$subdesc) {
 314                 if (!array_key_exists($key, $params)) {
 315                     if ($subdesc->required == VALUE_REQUIRED) {
 316                         throw new invalid_parameter_exception('Missing required key in single structure: '. $key);
 317                     }
 318                     if ($subdesc->required == VALUE_DEFAULT) {
 319                         try {
 320                             $result[$key] = self::validate_parameters($subdesc, $subdesc->default);
 321                         } catch (invalid_parameter_exception $e) {
 322                             //we are only interested by exceptions returned by validate_param() and validate_parameters()
 323                             //(in order to build the path to the faulty attribut)
 324                             throw new invalid_parameter_exception($key." => ".$e->getMessage() . ': ' .$e->debuginfo);
 325                         }
 326                     }
 327                 } else {
 328                     try {
 329                         $result[$key] = self::validate_parameters($subdesc, $params[$key]);
 330                     } catch (invalid_parameter_exception $e) {
 331                         //we are only interested by exceptions returned by validate_param() and validate_parameters()
 332                         //(in order to build the path to the faulty attribut)
 333                         throw new invalid_parameter_exception($key." => ".$e->getMessage() . ': ' .$e->debuginfo);
 334                     }
 335                 }
 336                 unset($params[$key]);
 337             }
 338             if (!empty($params)) {
 339                 throw new invalid_parameter_exception('Unexpected keys (' . implode(', ', array_keys($params)) . ') detected in parameter array.');
 340             }
 341             return $result;
 342
 343         } else if ($description instanceof external_multiple_structure) {
 344             if (!is_array($params)) {
 345                 throw new invalid_parameter_exception('Only arrays accepted. The bad value is: \''
 346                         . print_r($params, true) . '\'');
 347             }
 348             $result = array();
 349             foreach ($params as $param) {
 350                 $result[] = self::validate_parameters($description->content, $param);
 351             }
 352             return $result;
 353
 354         } else {
 355             throw new invalid_parameter_exception('Invalid external api description');
 356         }
 357     }
 358
 359     /**
 360      * Clean response
 361      * If a response attribute is unknown from the description, we just ignore the attribute.
 362      * If a response attribute is incorrect, invalid_response_exception is thrown.
 363      * Note: this function is similar to validate parameters, however it is distinct because
 364      * parameters validation must be distinct from cleaning return values.
 365      *
 366      * @param external_description $description description of the return values
 367      * @param mixed $response the actual response
 368      * @return mixed response with added defaults for optional items, invalid_response_exception thrown if any problem found
 369      * @author 2010 Jerome Mouneyrac
 370      * @since Moodle 2.0
 371      */
 372     public static function clean_returnvalue(external_description $description, $response) {
 373         if ($description instanceof external_value) {
 374             if (is_array($response) or is_object($response)) {
 375                 throw new invalid_response_exception('Scalar type expected, array or object received.');
 376             }
 377
 378             if ($description->type == PARAM_BOOL) {
 379                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 380                 if (is_bool($response) or $response === 0 or $response === 1 or $response === '0' or $response === '1') {
 381                     return (bool)$response;
 382                 }
 383             }
 384             $debuginfo = 'Invalid external api response: the value is "' . $response .
 385                     '", the server was expecting "' . $description->type . '" type';
 386             try {
 387                 return validate_param($response, $description->type, $description->allownull, $debuginfo);
 388             } catch (invalid_parameter_exception $e) {
 389                 //proper exception name, to be recursively catched to build the path to the faulty attribut
 390                 throw new invalid_response_exception($e->debuginfo);
 391             }
 392
 393         } else if ($description instanceof external_single_structure) {
 394             if (!is_array($response) && !is_object($response)) {
 395                 throw new invalid_response_exception('Only arrays/objects accepted. The bad value is: \'' .
 396                         print_r($response, true) . '\'');
 397             }
 398
 399             // Cast objects into arrays.
 400             if (is_object($response)) {
 401                 $response = (array) $response;
 402             }
 403
 404             $result = array();
 405             foreach ($description->keys as $key=>$subdesc) {
 406                 if (!array_key_exists($key, $response)) {
 407                     if ($subdesc->required == VALUE_REQUIRED) {
 408                         throw new invalid_response_exception('Error in response - Missing following required key in a single structure: ' . $key);
 409                     }
 410                     if ($subdesc instanceof external_value) {
 411                         if ($subdesc->required == VALUE_DEFAULT) {
 412                             try {
 413                                     $result[$key] = self::clean_returnvalue($subdesc, $subdesc->default);
 414                             } catch (invalid_response_exception $e) {
 415                                 //build the path to the faulty attribut
 416                                 throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 417                             }
 418                         }
 419                     }
 420                 } else {
 421                     try {
 422                         $result[$key] = self::clean_returnvalue($subdesc, $response[$key]);
 423                     } catch (invalid_response_exception $e) {
 424                         //build the path to the faulty attribut
 425                         throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 426                     }
 427                 }
 428                 unset($response[$key]);
 429             }
 430
 431             return $result;
 432
 433         } else if ($description instanceof external_multiple_structure) {
 434             if (!is_array($response)) {
 435                 throw new invalid_response_exception('Only arrays accepted. The bad value is: \'' .
 436                         print_r($response, true) . '\'');
 437             }
 438             $result = array();
 439             foreach ($response as $param) {
 440                 $result[] = self::clean_returnvalue($description->content, $param);
 441             }
 442             return $result;
 443
 444         } else {
 445             throw new invalid_response_exception('Invalid external api response description');
 446         }
 447     }
 448
 449     /**
 450      * Makes sure user may execute functions in this context.
 451      *
 452      * @param stdClass $context
 453      * @since Moodle 2.0
 454      */
 455     public static function validate_context($context) {
 456         global $CFG, $PAGE;
 457
 458         if (empty($context)) {
 459             throw new invalid_parameter_exception('Context does not exist');
 460         }
 461         if (empty(self::$contextrestriction)) {
 462             self::$contextrestriction = context_system::instance();
 463         }
 464         $rcontext = self::$contextrestriction;
 465
 466         if ($rcontext->contextlevel == $context->contextlevel) {
 467             if ($rcontext->id != $context->id) {
 468                 throw new restricted_context_exception();
 469             }
 470         } else if ($rcontext->contextlevel > $context->contextlevel) {
 471             throw new restricted_context_exception();
 472         } else {
 473             $parents = $context->get_parent_context_ids();
 474             if (!in_array($rcontext->id, $parents)) {
 475                 throw new restricted_context_exception();
 476             }
 477         }
 478
 479         $PAGE->reset_theme_and_output();
 480         list($unused, $course, $cm) = get_context_info_array($context->id);
 481         require_login($course, false, $cm, false, true);
 482         $PAGE->set_context($context);
 483     }
 484
 485     /**
 486      * Get context from passed parameters.
 487      * The passed array must either contain a contextid or a combination of context level and instance id to fetch the context.
 488      * For example, the context level can be "course" and instanceid can be courseid.
 489      *
 490      * See context_helper::get_all_levels() for a list of valid context levels.
 491      *
 492      * @param array $param
 493      * @since Moodle 2.6
 494      * @throws invalid_parameter_exception
 495      * @return context
 496      */
 497     protected static function get_context_from_params($param) {
 498         $levels = context_helper::get_all_levels();
 499         if (!empty($param['contextid'])) {
 500             return context::instance_by_id($param['contextid'], IGNORE_MISSING);
 501         } else if (!empty($param['contextlevel']) && isset($param['instanceid'])) {
 502             $contextlevel = "context_".$param['contextlevel'];
 503             if (!array_search($contextlevel, $levels)) {
 504                 throw new invalid_parameter_exception('Invalid context level = '.$param['contextlevel']);
 505             }
 506            return $contextlevel::instance($param['instanceid'], IGNORE_MISSING);
 507         } else {
 508             // No valid context info was found.
 509             throw new invalid_parameter_exception('Missing parameters, please provide either context level with instance id or contextid');
 510         }
 511     }
 512 }
 513
 514 /**
 515  * Common ancestor of all parameter description classes
 516  *
 517  * @package    core_webservice
 518  * @copyright  2009 Petr Skodak
 519  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 520  * @since Moodle 2.0
 521  */
 522 abstract class external_description {
 523     /** @var string Description of element */
 524     public $desc;
 525
 526     /** @var bool Element value required, null not allowed */
 527     public $required;
 528
 529     /** @var mixed Default value */
 530     public $default;
 531
 532     /**
 533      * Contructor
 534      *
 535      * @param string $desc
 536      * @param bool $required
 537      * @param mixed $default
 538      * @since Moodle 2.0
 539      */
 540     public function __construct($desc, $required, $default) {
 541         $this->desc = $desc;
 542         $this->required = $required;
 543         $this->default = $default;
 544     }
 545 }
 546
 547 /**
 548  * Scalar value description class
 549  *
 550  * @package    core_webservice
 551  * @copyright  2009 Petr Skodak
 552  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 553  * @since Moodle 2.0
 554  */
 555 class external_value extends external_description {
 556
 557     /** @var mixed Value type PARAM_XX */
 558     public $type;
 559
 560     /** @var bool Allow null values */
 561     public $allownull;
 562
 563     /**
 564      * Constructor
 565      *
 566      * @param mixed $type
 567      * @param string $desc
 568      * @param bool $required
 569      * @param mixed $default
 570      * @param bool $allownull
 571      * @since Moodle 2.0
 572      */
 573     public function __construct($type, $desc='', $required=VALUE_REQUIRED,
 574             $default=null, $allownull=NULL_ALLOWED) {
 575         parent::__construct($desc, $required, $default);
 576         $this->type      = $type;
 577         $this->allownull = $allownull;
 578     }
 579 }
 580
 581 /**
 582  * Associative array description class
 583  *
 584  * @package    core_webservice
 585  * @copyright  2009 Petr Skodak
 586  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 587  * @since Moodle 2.0
 588  */
 589 class external_single_structure extends external_description {
 590
 591      /** @var array Description of array keys key=>external_description */
 592     public $keys;
 593
 594     /**
 595      * Constructor
 596      *
 597      * @param array $keys
 598      * @param string $desc
 599      * @param bool $required
 600      * @param array $default
 601      * @since Moodle 2.0
 602      */
 603     public function __construct(array $keys, $desc='',
 604             $required=VALUE_REQUIRED, $default=null) {
 605         parent::__construct($desc, $required, $default);
 606         $this->keys = $keys;
 607     }
 608 }
 609
 610 /**
 611  * Bulk array description class.
 612  *
 613  * @package    core_webservice
 614  * @copyright  2009 Petr Skodak
 615  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 616  * @since Moodle 2.0
 617  */
 618 class external_multiple_structure extends external_description {
 619
 620      /** @var external_description content */
 621     public $content;
 622
 623     /**
 624      * Constructor
 625      *
 626      * @param external_description $content
 627      * @param string $desc
 628      * @param bool $required
 629      * @param array $default
 630      * @since Moodle 2.0
 631      */
 632     public function __construct(external_description $content, $desc='',
 633             $required=VALUE_REQUIRED, $default=null) {
 634         parent::__construct($desc, $required, $default);
 635         $this->content = $content;
 636     }
 637 }
 638
 639 /**
 640  * Description of top level - PHP function parameters.
 641  *
 642  * @package    core_webservice
 643  * @copyright  2009 Petr Skodak
 644  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 645  * @since Moodle 2.0
 646  */
 647 class external_function_parameters extends external_single_structure {
 648
 649     /**
 650      * Constructor - does extra checking to prevent top level optional parameters.
 651      *
 652      * @param array $keys
 653      * @param string $desc
 654      * @param bool $required
 655      * @param array $default
 656      */
 657     public function __construct(array $keys, $desc='', $required=VALUE_REQUIRED, $default=null) {
 658         global $CFG;
 659
 660         if ($CFG->debugdeveloper) {
 661             foreach ($keys as $key => $value) {
 662                 if ($value instanceof external_value) {
 663                     if ($value->required == VALUE_OPTIONAL) {
 664                         debugging('External function parameters: invalid OPTIONAL value specified.', DEBUG_DEVELOPER);
 665                         break;
 666                     }
 667                 }
 668             }
 669         }
 670         parent::__construct($keys, $desc, $required, $default);
 671     }
 672 }
 673
 674 /**
 675  * Generate a token
 676  *
 677  * @param string $tokentype EXTERNAL_TOKEN_EMBEDDED|EXTERNAL_TOKEN_PERMANENT
 678  * @param stdClass|int $serviceorid service linked to the token
 679  * @param int $userid user linked to the token
 680  * @param stdClass|int $contextorid
 681  * @param int $validuntil date when the token expired
 682  * @param string $iprestriction allowed ip - if 0 or empty then all ips are allowed
 683  * @return string generated token
 684  * @author  2010 Jamie Pratt
 685  * @since Moodle 2.0
 686  */
 687 function external_generate_token($tokentype, $serviceorid, $userid, $contextorid, $validuntil=0, $iprestriction=''){
 688     global $DB, $USER;
 689     // make sure the token doesn't exist (even if it should be almost impossible with the random generation)
 690     $numtries = 0;
 691     do {
 692         $numtries ++;
 693         $generatedtoken = md5(uniqid(rand(),1));
 694         if ($numtries > 5){
 695             throw new moodle_exception('tokengenerationfailed');
 696         }
 697     } while ($DB->record_exists('external_tokens', array('token'=>$generatedtoken)));
 698     $newtoken = new stdClass();
 699     $newtoken->token = $generatedtoken;
 700     if (!is_object($serviceorid)){
 701         $service = $DB->get_record('external_services', array('id' => $serviceorid));
 702     } else {
 703         $service = $serviceorid;
 704     }
 705     if (!is_object($contextorid)){
 706         $context = context::instance_by_id($contextorid, MUST_EXIST);
 707     } else {
 708         $context = $contextorid;
 709     }
 710     if (empty($service->requiredcapability) || has_capability($service->requiredcapability, $context, $userid)) {
 711         $newtoken->externalserviceid = $service->id;
 712     } else {
 713         throw new moodle_exception('nocapabilitytousethisservice');
 714     }
 715     $newtoken->tokentype = $tokentype;
 716     $newtoken->userid = $userid;
 717     if ($tokentype == EXTERNAL_TOKEN_EMBEDDED){
 718         $newtoken->sid = session_id();
 719     }
 720
 721     $newtoken->contextid = $context->id;
 722     $newtoken->creatorid = $USER->id;
 723     $newtoken->timecreated = time();
 724     $newtoken->validuntil = $validuntil;
 725     if (!empty($iprestriction)) {
 726         $newtoken->iprestriction = $iprestriction;
 727     }
 728     $DB->insert_record('external_tokens', $newtoken);
 729     return $newtoken->token;
 730 }
 731
 732 /**
 733  * Create and return a session linked token. Token to be used for html embedded client apps that want to communicate
 734  * with the Moodle server through web services. The token is linked to the current session for the current page request.
 735  * It is expected this will be called in the script generating the html page that is embedding the client app and that the
 736  * returned token will be somehow passed into the client app being embedded in the page.
 737  *
 738  * @param string $servicename name of the web service. Service name as defined in db/services.php
 739  * @param int $context context within which the web service can operate.
 740  * @return int returns token id.
 741  * @since Moodle 2.0
 742  */
 743 function external_create_service_token($servicename, $context){
 744     global $USER, $DB;
 745     $service = $DB->get_record('external_services', array('name'=>$servicename), '*', MUST_EXIST);
 746     return external_generate_token(EXTERNAL_TOKEN_EMBEDDED, $service, $USER->id, $context, 0);
 747 }
 748
 749 /**
 750  * Delete all pre-built services (+ related tokens) and external functions information defined in the specified component.
 751  *
 752  * @param string $component name of component (moodle, mod_assignment, etc.)
 753  */
 754 function external_delete_descriptions($component) {
 755     global $DB;
 756
 757     $params = array($component);
 758
 759     $DB->delete_records_select('external_tokens',
 760             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 761     $DB->delete_records_select('external_services_users',
 762             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 763     $DB->delete_records_select('external_services_functions',
 764             "functionname IN (SELECT name FROM {external_functions} WHERE component = ?)", $params);
 765     $DB->delete_records('external_services', array('component'=>$component));
 766     $DB->delete_records('external_functions', array('component'=>$component));
 767 }
 768
 769 /**
 770  * Standard Moodle web service warnings
 771  *
 772  * @package    core_webservice
 773  * @copyright  2012 Jerome Mouneyrac
 774  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 775  * @since Moodle 2.3
 776  */
 777 class external_warnings extends external_multiple_structure {
 778
 779     /**
 780      * Constructor
 781      *
 782      * @since Moodle 2.3
 783      */
 784     public function __construct($itemdesc = 'item', $itemiddesc = 'item id',
 785         $warningcodedesc = 'the warning code can be used by the client app to implement specific behaviour') {
 786
 787         parent::__construct(
 788             new external_single_structure(
 789                 array(
 790                     'item' => new external_value(PARAM_TEXT, $itemdesc, VALUE_OPTIONAL),
 791                     'itemid' => new external_value(PARAM_INT, $itemiddesc, VALUE_OPTIONAL),
 792                     'warningcode' => new external_value(PARAM_ALPHANUM, $warningcodedesc),
 793                     'message' => new external_value(PARAM_TEXT,
 794                             'untranslated english message to explain the warning')
 795                 ), 'warning'),
 796             'list of warnings', VALUE_OPTIONAL);
 797     }
 798 }
 799
 800 /**
 801  * A pre-filled external_value class for text format.
 802  *
 803  * Default is FORMAT_HTML
 804  * This should be used all the time in external xxx_params()/xxx_returns functions
 805  * as it is the standard way to implement text format param/return values.
 806  *
 807  * @package    core_webservice
 808  * @copyright  2012 Jerome Mouneyrac
 809  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 810  * @since Moodle 2.3
 811  */
 812 class external_format_value extends external_value {
 813
 814     /**
 815      * Constructor
 816      *
 817      * @param string $textfieldname Name of the text field
 818      * @param int $required if VALUE_REQUIRED then set standard default FORMAT_HTML
 819      * @since Moodle 2.3
 820      */
 821     public function __construct($textfieldname, $required = VALUE_REQUIRED) {
 822
 823         $default = ($required == VALUE_DEFAULT) ? FORMAT_HTML : null;
 824
 825         $desc = $textfieldname . ' format (' . FORMAT_HTML . ' = HTML, '
 826                 . FORMAT_MOODLE . ' = MOODLE, '
 827                 . FORMAT_PLAIN . ' = PLAIN or '
 828                 . FORMAT_MARKDOWN . ' = MARKDOWN)';
 829
 830         parent::__construct(PARAM_INT, $desc, $required, $default);
 831     }
 832 }
 833
 834 /**
 835  * Validate text field format against known FORMAT_XXX
 836  *
 837  * @param array $format the format to validate
 838  * @return the validated format
 839  * @throws coding_exception
 840  * @since Moodle 2.3
 841  */
 842 function external_validate_format($format) {
 843     $allowedformats = array(FORMAT_HTML, FORMAT_MOODLE, FORMAT_PLAIN, FORMAT_MARKDOWN);
 844     if (!in_array($format, $allowedformats)) {
 845         throw new moodle_exception('formatnotsupported', 'webservice', '' , null,
 846                 'The format with value=' . $format . ' is not supported by this Moodle site');
 847     }
 848     return $format;
 849 }
 850
 851 /**
 852  * Format the string to be returned properly as requested by the either the web service server,
 853  * either by an internally call.
 854  * The caller can change the format (raw) with the external_settings singleton
 855  * All web service servers must set this singleton when parsing the $_GET and $_POST.
 856  *
 857  * <pre>
 858  * Options are the same that in {@link format_string()} with some changes:
 859  *      filter      : Can be set to false to force filters off, else observes {@link external_settings}.
 860  * </pre>
 861  *
 862  * @param string $str The string to be filtered. Should be plain text, expect
 863  * possibly for multilang tags.
 864  * @param boolean $striplinks To strip any link in the result text. Moodle 1.8 default changed from false to true! MDL-8713
 865  * @param int $contextid The id of the context for the string (affects filters).
 866  * @param array $options options array/object or courseid
 867  * @return string text
 868  * @since Moodle 3.0
 869  */
 870 function external_format_string($str, $contextid, $striplinks = true, $options = array()) {
 871
 872     // Get settings (singleton).
 873     $settings = external_settings::get_instance();
 874     if (empty($contextid)) {
 875         throw new coding_exception('contextid is required');
 876     }
 877
 878     if (!$settings->get_raw()) {
 879         $context = context::instance_by_id($contextid);
 880         $options['context'] = $context;
 881         $options['filter'] = isset($options['filter']) && !$options['filter'] ? false : $settings->get_filter();
 882         $str = format_string($str, $striplinks, $options);
 883     }
 884
 885     return $str;
 886 }
 887
 888 /**
 889  * Format the text to be returned properly as requested by the either the web service server,
 890  * either by an internally call.
 891  * The caller can change the format (raw, filter, file, fileurl) with the external_settings singleton
 892  * All web service servers must set this singleton when parsing the $_GET and $_POST.
 893  *
 894  * <pre>
 895  * Options are the same that in {@link format_text()} with some changes in defaults to provide backwards compatibility:
 896  *      trusted     :   If true the string won't be cleaned. Default false.
 897  *      noclean     :   If true the string won't be cleaned only if trusted is also true. Default false.
 898  *      nocache     :   If true the string will not be cached and will be formatted every call. Default false.
 899  *      filter      :   Can be set to false to force filters off, else observes {@link external_settings}.
 900  *      para        :   If true then the returned string will be wrapped in div tags. Default (different from format_text) false.
 901  *                      Default changed because div tags are not commonly needed.
 902  *      newlines    :   If true then lines newline breaks will be converted to HTML newline breaks. Default true.
 903  *      context     :   Not used! Using contextid parameter instead.
 904  *      overflowdiv :   If set to true the formatted text will be encased in a div with the class no-overflow before being
 905  *                      returned. Default false.
 906  *      allowid     :   If true then id attributes will not be removed, even when using htmlpurifier. Default (different from
 907  *                      format_text) true. Default changed id attributes are commonly needed.
 908  *      blanktarget :   If true all <a> tags will have target="_blank" added unless target is explicitly specified.
 909  * </pre>
 910  *
 911  * @param string $text The content that may contain ULRs in need of rewriting.
 912  * @param int $textformat The text format.
 913  * @param int $contextid This parameter and the next two identify the file area to use.
 914  * @param string $component
 915  * @param string $filearea helps identify the file area.
 916  * @param int $itemid helps identify the file area.
 917  * @param object/array $options text formatting options
 918  * @return array text + textformat
 919  * @since Moodle 2.3
 920  */
 921 function external_format_text($text, $textformat, $contextid, $component, $filearea, $itemid, $options = null) {
 922     global $CFG;
 923
 924     // Get settings (singleton).
 925     $settings = external_settings::get_instance();
 926
 927     if ($settings->get_fileurl()) {
 928         require_once($CFG->libdir . "/filelib.php");
 929         $text = file_rewrite_pluginfile_urls($text, $settings->get_file(), $contextid, $component, $filearea, $itemid);
 930     }
 931
 932     if (!$settings->get_raw()) {
 933         $options = (array)$options;
 934
 935         // If context is passed in options, check that is the same to show a debug message.
 936         if (isset($options['context'])) {
 937             if ((is_object($options['context']) && $options['context']->id != $contextid)
 938                     || (!is_object($options['context']) && $options['context'] != $contextid)) {
 939                 debugging('Different contexts found in external_format_text parameters. $options[\'context\'] not allowed.
 940                     Using $contextid parameter...', DEBUG_DEVELOPER);
 941             }
 942         }
 943
 944         $options['filter'] = isset($options['filter']) && !$options['filter'] ? false : $settings->get_filter();
 945         $options['para'] = isset($options['para']) ? $options['para'] : false;
 946         $options['context'] = context::instance_by_id($contextid);
 947         $options['allowid'] = isset($options['allowid']) ? $options['allowid'] : true;
 948
 949         $text = format_text($text, $textformat, $options);
 950         $textformat = FORMAT_HTML; // Once converted to html (from markdown, plain... lets inform consumer this is already HTML).
 951     }
 952
 953     return array($text, $textformat);
 954 }
 955
 956 /**
 957  * Singleton to handle the external settings.
 958  *
 959  * We use singleton to encapsulate the "logic"
 960  *
 961  * @package    core_webservice
 962  * @copyright  2012 Jerome Mouneyrac
 963  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 964  * @since Moodle 2.3
 965  */
 966 class external_settings {
 967
 968     /** @var object the singleton instance */
 969     public static $instance = null;
 970
 971     /** @var boolean Should the external function return raw text or formatted */
 972     private $raw = false;
 973
 974     /** @var boolean Should the external function filter the text */
 975     private $filter = false;
 976
 977     /** @var boolean Should the external function rewrite plugin file url */
 978     private $fileurl = true;
 979
 980     /** @var string In which file should the urls be rewritten */
 981     private $file = 'webservice/pluginfile.php';
 982
 983     /**
 984      * Constructor - protected - can not be instanciated
 985      */
 986     protected function __construct() {
 987         if ((AJAX_SCRIPT == false) && (CLI_SCRIPT == false) && (WS_SERVER == false)) {
 988             // For normal pages, the default should match the default for format_text.
 989             $this->filter = true;
 990             // Use pluginfile.php for web requests.
 991             $this->file = 'pluginfile.php';
 992         }
 993     }
 994
 995     /**
 996      * Clone - private - can not be cloned
 997      */
 998     private final function __clone() {
 999     }
1000
1001     /**
1002      * Return only one instance
1003      *
1004      * @return \external_settings
1005      */
1006     public static function get_instance() {
1007         if (self::$instance === null) {
1008             self::$instance = new external_settings;
1009         }
1010
1011         return self::$instance;
1012     }
1013
1014     /**
1015      * Set raw
1016      *
1017      * @param boolean $raw
1018      */
1019     public function set_raw($raw) {
1020         $this->raw = $raw;
1021     }
1022
1023     /**
1024      * Get raw
1025      *
1026      * @return boolean
1027      */
1028     public function get_raw() {
1029         return $this->raw;
1030     }
1031
1032     /**
1033      * Set filter
1034      *
1035      * @param boolean $filter
1036      */
1037     public function set_filter($filter) {
1038         $this->filter = $filter;
1039     }
1040
1041     /**
1042      * Get filter
1043      *
1044      * @return boolean
1045      */
1046     public function get_filter() {
1047         return $this->filter;
1048     }
1049
1050     /**
1051      * Set fileurl
1052      *
1053      * @param boolean $fileurl
1054      */
1055     public function set_fileurl($fileurl) {
1056         $this->fileurl = $fileurl;
1057     }
1058
1059     /**
1060      * Get fileurl
1061      *
1062      * @return boolean
1063      */
1064     public function get_fileurl() {
1065         return $this->fileurl;
1066     }
1067
1068     /**
1069      * Set file
1070      *
1071      * @param string $file
1072      */
1073     public function set_file($file) {
1074         $this->file = $file;
1075     }
1076
1077     /**
1078      * Get file
1079      *
1080      * @return string
1081      */
1082     public function get_file() {
1083         return $this->file;
1084     }
1085 }
1086
1087 /**
1088  * Utility functions for the external API.
1089  *
1090  * @package    core_webservice
1091  * @copyright  2015 Juan Leyva
1092  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
1093  * @since Moodle 3.0
1094  */
1095 class external_util {
1096
1097     /**
1098      * Validate a list of courses, returning the complete course objects for valid courses.
1099      *
1100      * @param  array $courseids A list of course ids
1101      * @param  array $courses   An array of courses already pre-fetched, indexed by course id.
1102      * @return array            An array of courses and the validation warnings
1103      */
1104     public static function validate_courses($courseids, $courses = array()) {
1105         // Delete duplicates.
1106         $courseids = array_unique($courseids);
1107         $warnings = array();
1108
1109         // Remove courses which are not even requested.
1110         $courses =  array_intersect_key($courses, array_flip($courseids));
1111
1112         foreach ($courseids as $cid) {
1113             // Check the user can function in this context.
1114             try {
1115                 $context = context_course::instance($cid);
1116                 external_api::validate_context($context);
1117
1118                 if (!isset($courses[$cid])) {
1119                     $courses[$cid] = get_course($cid);
1120                 }
1121             } catch (Exception $e) {
1122                 unset($courses[$cid]);
1123                 $warnings[] = array(
1124                     'item' => 'course',
1125                     'itemid' => $cid,
1126                     'warningcode' => '1',
1127                     'message' => 'No access rights in course context'
1128                 );
1129             }
1130         }
1131
1132         return array($courses, $warnings);
1133     }
1134
1135 }