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  * Returns detailed function information
  30  *
  31  * @param string|object $function name of external function or record from external_function
  32  * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
  33  *                        MUST_EXIST means throw exception if no record or multiple records found
  34  * @return stdClass description or false if not found or exception thrown
  35  * @since Moodle 2.0
  36  */
  37 function external_function_info($function, $strictness=MUST_EXIST) {
  38     global $DB, $CFG;
  39
  40     if (!is_object($function)) {
  41         if (!$function = $DB->get_record('external_functions', array('name'=>$function), '*', $strictness)) {
  42             return false;
  43         }
  44     }
  45
  46     //first find and include the ext implementation class
  47     $function->classpath = empty($function->classpath) ? get_component_directory($function->component).'/externallib.php' : $CFG->dirroot.'/'.$function->classpath;
  48     if (!file_exists($function->classpath)) {
  49         throw new coding_exception('Can not find file with external function implementation');
  50     }
  51     require_once($function->classpath);
  52
  53     $function->parameters_method = $function->methodname.'_parameters';
  54     $function->returns_method    = $function->methodname.'_returns';
  55
  56     // make sure the implementaion class is ok
  57     if (!method_exists($function->classname, $function->methodname)) {
  58         throw new coding_exception('Missing implementation method of '.$function->classname.'::'.$function->methodname);
  59     }
  60     if (!method_exists($function->classname, $function->parameters_method)) {
  61         throw new coding_exception('Missing parameters description');
  62     }
  63     if (!method_exists($function->classname, $function->returns_method)) {
  64         throw new coding_exception('Missing returned values description');
  65     }
  66
  67     // fetch the parameters description
  68     $function->parameters_desc = call_user_func(array($function->classname, $function->parameters_method));
  69     if (!($function->parameters_desc instanceof external_function_parameters)) {
  70         throw new coding_exception('Invalid parameters description');
  71     }
  72
  73     // fetch the return values description
  74     $function->returns_desc = call_user_func(array($function->classname, $function->returns_method));
  75     // null means void result or result is ignored
  76     if (!is_null($function->returns_desc) and !($function->returns_desc instanceof external_description)) {
  77         throw new coding_exception('Invalid return description');
  78     }
  79
  80     //now get the function description
  81     //TODO MDL-31115 use localised lang pack descriptions, it would be nice to have
  82     //      easy to understand descriptions in admin UI,
  83     //      on the other hand this is still a bit in a flux and we need to find some new naming
  84     //      conventions for these descriptions in lang packs
  85     $function->description = null;
  86     $servicesfile = get_component_directory($function->component).'/db/services.php';
  87     if (file_exists($servicesfile)) {
  88         $functions = null;
  89         include($servicesfile);
  90         if (isset($functions[$function->name]['description'])) {
  91             $function->description = $functions[$function->name]['description'];
  92         }
  93         if (isset($functions[$function->name]['testclientpath'])) {
  94             $function->testclientpath = $functions[$function->name]['testclientpath'];
  95         }
  96     }
  97
  98     return $function;
  99 }
 100
 101 /**
 102  * Exception indicating user is not allowed to use external function in the current context.
 103  *
 104  * @package    core_webservice
 105  * @copyright  2009 Petr Skodak
 106  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 107  * @since Moodle 2.0
 108  */
 109 class restricted_context_exception extends moodle_exception {
 110     /**
 111      * Constructor
 112      *
 113      * @since Moodle 2.0
 114      */
 115     function __construct() {
 116         parent::__construct('restrictedcontextexception', 'error');
 117     }
 118 }
 119
 120 /**
 121  * Base class for external api methods.
 122  *
 123  * @package    core_webservice
 124  * @copyright  2009 Petr Skodak
 125  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 126  * @since Moodle 2.0
 127  */
 128 class external_api {
 129
 130     /** @var stdClass context where the function calls will be restricted */
 131     private static $contextrestriction;
 132
 133     /**
 134      * Set context restriction for all following subsequent function calls.
 135      *
 136      * @param stdClass $context the context restriction
 137      * @since Moodle 2.0
 138      */
 139     public static function set_context_restriction($context) {
 140         self::$contextrestriction = $context;
 141     }
 142
 143     /**
 144      * This method has to be called before every operation
 145      * that takes a longer time to finish!
 146      *
 147      * @param int $seconds max expected time the next operation needs
 148      * @since Moodle 2.0
 149      */
 150     public static function set_timeout($seconds=360) {
 151         $seconds = ($seconds < 300) ? 300 : $seconds;
 152         set_time_limit($seconds);
 153     }
 154
 155     /**
 156      * Validates submitted function parameters, if anything is incorrect
 157      * invalid_parameter_exception is thrown.
 158      * This is a simple recursive method which is intended to be called from
 159      * each implementation method of external API.
 160      *
 161      * @param external_description $description description of parameters
 162      * @param mixed $params the actual parameters
 163      * @return mixed params with added defaults for optional items, invalid_parameters_exception thrown if any problem found
 164      * @since Moodle 2.0
 165      */
 166     public static function validate_parameters(external_description $description, $params) {
 167         if ($description instanceof external_value) {
 168             if (is_array($params) or is_object($params)) {
 169                 throw new invalid_parameter_exception('Scalar type expected, array or object received.');
 170             }
 171
 172             if ($description->type == PARAM_BOOL) {
 173                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 174                 if (is_bool($params) or $params === 0 or $params === 1 or $params === '0' or $params === '1') {
 175                     return (bool)$params;
 176                 }
 177             }
 178             $debuginfo = 'Invalid external api parameter: the value is "' . $params .
 179                     '", the server was expecting "' . $description->type . '" type';
 180             return validate_param($params, $description->type, $description->allownull, $debuginfo);
 181
 182         } else if ($description instanceof external_single_structure) {
 183             if (!is_array($params)) {
 184                 throw new invalid_parameter_exception('Only arrays accepted. The bad value is: \''
 185                         . print_r($params, true) . '\'');
 186             }
 187             $result = array();
 188             foreach ($description->keys as $key=>$subdesc) {
 189                 if (!array_key_exists($key, $params)) {
 190                     if ($subdesc->required == VALUE_REQUIRED) {
 191                         throw new invalid_parameter_exception('Missing required key in single structure: '. $key);
 192                     }
 193                     if ($subdesc->required == VALUE_DEFAULT) {
 194                         try {
 195                             $result[$key] = self::validate_parameters($subdesc, $subdesc->default);
 196                         } catch (invalid_parameter_exception $e) {
 197                             //we are only interested by exceptions returned by validate_param() and validate_parameters()
 198                             //(in order to build the path to the faulty attribut)
 199                             throw new invalid_parameter_exception($key." => ".$e->getMessage() . ': ' .$e->debuginfo);
 200                         }
 201                     }
 202                 } else {
 203                     try {
 204                         $result[$key] = self::validate_parameters($subdesc, $params[$key]);
 205                     } catch (invalid_parameter_exception $e) {
 206                         //we are only interested by exceptions returned by validate_param() and validate_parameters()
 207                         //(in order to build the path to the faulty attribut)
 208                         throw new invalid_parameter_exception($key." => ".$e->getMessage() . ': ' .$e->debuginfo);
 209                     }
 210                 }
 211                 unset($params[$key]);
 212             }
 213             if (!empty($params)) {
 214                 throw new invalid_parameter_exception('Unexpected keys (' . implode(', ', array_keys($params)) . ') detected in parameter array.');
 215             }
 216             return $result;
 217
 218         } else if ($description instanceof external_multiple_structure) {
 219             if (!is_array($params)) {
 220                 throw new invalid_parameter_exception('Only arrays accepted. The bad value is: \''
 221                         . print_r($params, true) . '\'');
 222             }
 223             $result = array();
 224             foreach ($params as $param) {
 225                 $result[] = self::validate_parameters($description->content, $param);
 226             }
 227             return $result;
 228
 229         } else {
 230             throw new invalid_parameter_exception('Invalid external api description');
 231         }
 232     }
 233
 234     /**
 235      * Clean response
 236      * If a response attribute is unknown from the description, we just ignore the attribute.
 237      * If a response attribute is incorrect, invalid_response_exception is thrown.
 238      * Note: this function is similar to validate parameters, however it is distinct because
 239      * parameters validation must be distinct from cleaning return values.
 240      *
 241      * @param external_description $description description of the return values
 242      * @param mixed $response the actual response
 243      * @return mixed response with added defaults for optional items, invalid_response_exception thrown if any problem found
 244      * @author 2010 Jerome Mouneyrac
 245      * @since Moodle 2.0
 246      */
 247     public static function clean_returnvalue(external_description $description, $response) {
 248         if ($description instanceof external_value) {
 249             if (is_array($response) or is_object($response)) {
 250                 throw new invalid_response_exception('Scalar type expected, array or object received.');
 251             }
 252
 253             if ($description->type == PARAM_BOOL) {
 254                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 255                 if (is_bool($response) or $response === 0 or $response === 1 or $response === '0' or $response === '1') {
 256                     return (bool)$response;
 257                 }
 258             }
 259             $debuginfo = 'Invalid external api response: the value is "' . $response .
 260                     '", the server was expecting "' . $description->type . '" type';
 261             try {
 262                 return validate_param($response, $description->type, $description->allownull, $debuginfo);
 263             } catch (invalid_parameter_exception $e) {
 264                 //proper exception name, to be recursively catched to build the path to the faulty attribut
 265                 throw new invalid_response_exception($e->debuginfo);
 266             }
 267
 268         } else if ($description instanceof external_single_structure) {
 269             if (!is_array($response) && !is_object($response)) {
 270                 throw new invalid_response_exception('Only arrays/objects accepted. The bad value is: \'' .
 271                         print_r($response, true) . '\'');
 272             }
 273
 274             // Cast objects into arrays.
 275             if (is_object($response)) {
 276                 $response = (array) $response;
 277             }
 278
 279             $result = array();
 280             foreach ($description->keys as $key=>$subdesc) {
 281                 if (!array_key_exists($key, $response)) {
 282                     if ($subdesc->required == VALUE_REQUIRED) {
 283                         throw new invalid_response_exception('Error in response - Missing following required key in a single structure: ' . $key);
 284                     }
 285                     if ($subdesc instanceof external_value) {
 286                         if ($subdesc->required == VALUE_DEFAULT) {
 287                             try {
 288                                     $result[$key] = self::clean_returnvalue($subdesc, $subdesc->default);
 289                             } catch (invalid_response_exception $e) {
 290                                 //build the path to the faulty attribut
 291                                 throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 292                             }
 293                         }
 294                     }
 295                 } else {
 296                     try {
 297                         $result[$key] = self::clean_returnvalue($subdesc, $response[$key]);
 298                     } catch (invalid_response_exception $e) {
 299                         //build the path to the faulty attribut
 300                         throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 301                     }
 302                 }
 303                 unset($response[$key]);
 304             }
 305
 306             return $result;
 307
 308         } else if ($description instanceof external_multiple_structure) {
 309             if (!is_array($response)) {
 310                 throw new invalid_response_exception('Only arrays accepted. The bad value is: \'' .
 311                         print_r($response, true) . '\'');
 312             }
 313             $result = array();
 314             foreach ($response as $param) {
 315                 $result[] = self::clean_returnvalue($description->content, $param);
 316             }
 317             return $result;
 318
 319         } else {
 320             throw new invalid_response_exception('Invalid external api response description');
 321         }
 322     }
 323
 324     /**
 325      * Makes sure user may execute functions in this context.
 326      *
 327      * @param stdClass $context
 328      * @since Moodle 2.0
 329      */
 330     protected static function validate_context($context) {
 331         global $CFG;
 332
 333         if (empty($context)) {
 334             throw new invalid_parameter_exception('Context does not exist');
 335         }
 336         if (empty(self::$contextrestriction)) {
 337             self::$contextrestriction = context_system::instance();
 338         }
 339         $rcontext = self::$contextrestriction;
 340
 341         if ($rcontext->contextlevel == $context->contextlevel) {
 342             if ($rcontext->id != $context->id) {
 343                 throw new restricted_context_exception();
 344             }
 345         } else if ($rcontext->contextlevel > $context->contextlevel) {
 346             throw new restricted_context_exception();
 347         } else {
 348             $parents = get_parent_contexts($context);
 349             if (!in_array($rcontext->id, $parents)) {
 350                 throw new restricted_context_exception();
 351             }
 352         }
 353
 354         if ($context->contextlevel >= CONTEXT_COURSE) {
 355             list($context, $course, $cm) = get_context_info_array($context->id);
 356             require_login($course, false, $cm, false, true);
 357         }
 358     }
 359 }
 360
 361 /**
 362  * Common ancestor of all parameter description classes
 363  *
 364  * @package    core_webservice
 365  * @copyright  2009 Petr Skodak
 366  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 367  * @since Moodle 2.0
 368  */
 369 abstract class external_description {
 370     /** @var string Description of element */
 371     public $desc;
 372
 373     /** @var bool Element value required, null not allowed */
 374     public $required;
 375
 376     /** @var mixed Default value */
 377     public $default;
 378
 379     /**
 380      * Contructor
 381      *
 382      * @param string $desc
 383      * @param bool $required
 384      * @param mixed $default
 385      * @since Moodle 2.0
 386      */
 387     public function __construct($desc, $required, $default) {
 388         $this->desc = $desc;
 389         $this->required = $required;
 390         $this->default = $default;
 391     }
 392 }
 393
 394 /**
 395  * Scalar value description class
 396  *
 397  * @package    core_webservice
 398  * @copyright  2009 Petr Skodak
 399  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 400  * @since Moodle 2.0
 401  */
 402 class external_value extends external_description {
 403
 404     /** @var mixed Value type PARAM_XX */
 405     public $type;
 406
 407     /** @var bool Allow null values */
 408     public $allownull;
 409
 410     /**
 411      * Constructor
 412      *
 413      * @param mixed $type
 414      * @param string $desc
 415      * @param bool $required
 416      * @param mixed $default
 417      * @param bool $allownull
 418      * @since Moodle 2.0
 419      */
 420     public function __construct($type, $desc='', $required=VALUE_REQUIRED,
 421             $default=null, $allownull=NULL_ALLOWED) {
 422         parent::__construct($desc, $required, $default);
 423         $this->type      = $type;
 424         $this->allownull = $allownull;
 425     }
 426 }
 427
 428 /**
 429  * Associative array description class
 430  *
 431  * @package    core_webservice
 432  * @copyright  2009 Petr Skodak
 433  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 434  * @since Moodle 2.0
 435  */
 436 class external_single_structure extends external_description {
 437
 438      /** @var array Description of array keys key=>external_description */
 439     public $keys;
 440
 441     /**
 442      * Constructor
 443      *
 444      * @param array $keys
 445      * @param string $desc
 446      * @param bool $required
 447      * @param array $default
 448      * @since Moodle 2.0
 449      */
 450     public function __construct(array $keys, $desc='',
 451             $required=VALUE_REQUIRED, $default=null) {
 452         parent::__construct($desc, $required, $default);
 453         $this->keys = $keys;
 454     }
 455 }
 456
 457 /**
 458  * Bulk array description class.
 459  *
 460  * @package    core_webservice
 461  * @copyright  2009 Petr Skodak
 462  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 463  * @since Moodle 2.0
 464  */
 465 class external_multiple_structure extends external_description {
 466
 467      /** @var external_description content */
 468     public $content;
 469
 470     /**
 471      * Constructor
 472      *
 473      * @param external_description $content
 474      * @param string $desc
 475      * @param bool $required
 476      * @param array $default
 477      * @since Moodle 2.0
 478      */
 479     public function __construct(external_description $content, $desc='',
 480             $required=VALUE_REQUIRED, $default=null) {
 481         parent::__construct($desc, $required, $default);
 482         $this->content = $content;
 483     }
 484 }
 485
 486 /**
 487  * Description of top level - PHP function parameters.
 488  *
 489  * @package    core_webservice
 490  * @copyright  2009 Petr Skodak
 491  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 492  * @since Moodle 2.0
 493  */
 494 class external_function_parameters extends external_single_structure {
 495 }
 496
 497 /**
 498  * Generate a token
 499  *
 500  * @param string $tokentype EXTERNAL_TOKEN_EMBEDDED|EXTERNAL_TOKEN_PERMANENT
 501  * @param stdClass|int $serviceorid service linked to the token
 502  * @param int $userid user linked to the token
 503  * @param stdClass|int $contextorid
 504  * @param int $validuntil date when the token expired
 505  * @param string $iprestriction allowed ip - if 0 or empty then all ips are allowed
 506  * @return string generated token
 507  * @author  2010 Jamie Pratt
 508  * @since Moodle 2.0
 509  */
 510 function external_generate_token($tokentype, $serviceorid, $userid, $contextorid, $validuntil=0, $iprestriction=''){
 511     global $DB, $USER;
 512     // make sure the token doesn't exist (even if it should be almost impossible with the random generation)
 513     $numtries = 0;
 514     do {
 515         $numtries ++;
 516         $generatedtoken = md5(uniqid(rand(),1));
 517         if ($numtries > 5){
 518             throw new moodle_exception('tokengenerationfailed');
 519         }
 520     } while ($DB->record_exists('external_tokens', array('token'=>$generatedtoken)));
 521     $newtoken = new stdClass();
 522     $newtoken->token = $generatedtoken;
 523     if (!is_object($serviceorid)){
 524         $service = $DB->get_record('external_services', array('id' => $serviceorid));
 525     } else {
 526         $service = $serviceorid;
 527     }
 528     if (!is_object($contextorid)){
 529         $context = context::instance_by_id($contextorid, MUST_EXIST);
 530     } else {
 531         $context = $contextorid;
 532     }
 533     if (empty($service->requiredcapability) || has_capability($service->requiredcapability, $context, $userid)) {
 534         $newtoken->externalserviceid = $service->id;
 535     } else {
 536         throw new moodle_exception('nocapabilitytousethisservice');
 537     }
 538     $newtoken->tokentype = $tokentype;
 539     $newtoken->userid = $userid;
 540     if ($tokentype == EXTERNAL_TOKEN_EMBEDDED){
 541         $newtoken->sid = session_id();
 542     }
 543
 544     $newtoken->contextid = $context->id;
 545     $newtoken->creatorid = $USER->id;
 546     $newtoken->timecreated = time();
 547     $newtoken->validuntil = $validuntil;
 548     if (!empty($iprestriction)) {
 549         $newtoken->iprestriction = $iprestriction;
 550     }
 551     $DB->insert_record('external_tokens', $newtoken);
 552     return $newtoken->token;
 553 }
 554
 555 /**
 556  * Create and return a session linked token. Token to be used for html embedded client apps that want to communicate
 557  * with the Moodle server through web services. The token is linked to the current session for the current page request.
 558  * It is expected this will be called in the script generating the html page that is embedding the client app and that the
 559  * returned token will be somehow passed into the client app being embedded in the page.
 560  *
 561  * @param string $servicename name of the web service. Service name as defined in db/services.php
 562  * @param int $context context within which the web service can operate.
 563  * @return int returns token id.
 564  * @since Moodle 2.0
 565  */
 566 function external_create_service_token($servicename, $context){
 567     global $USER, $DB;
 568     $service = $DB->get_record('external_services', array('name'=>$servicename), '*', MUST_EXIST);
 569     return external_generate_token(EXTERNAL_TOKEN_EMBEDDED, $service, $USER->id, $context, 0);
 570 }
 571
 572 /**
 573  * Delete all pre-built services (+ related tokens) and external functions information defined in the specified component.
 574  *
 575  * @param string $component name of component (moodle, mod_assignment, etc.)
 576  */
 577 function external_delete_descriptions($component) {
 578     global $DB;
 579
 580     $params = array($component);
 581
 582     $DB->delete_records_select('external_tokens',
 583             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 584     $DB->delete_records_select('external_services_users',
 585             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 586     $DB->delete_records_select('external_services_functions',
 587             "functionname IN (SELECT name FROM {external_functions} WHERE component = ?)", $params);
 588     $DB->delete_records('external_services', array('component'=>$component));
 589     $DB->delete_records('external_functions', array('component'=>$component));
 590 }
 591
 592 /**
 593  * Standard Moodle web service warnings
 594  *
 595  * @package    core_webservice
 596  * @copyright  2012 Jerome Mouneyrac
 597  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 598  * @since Moodle 2.3
 599  */
 600 class external_warnings extends external_multiple_structure {
 601
 602     /**
 603      * Constructor
 604      *
 605      * @since Moodle 2.3
 606      */
 607     public function __construct($itemdesc = 'item', $itemiddesc = 'item id',
 608         $warningcodedesc = 'the warning code can be used by the client app to implement specific behaviour') {
 609
 610         parent::__construct(
 611             new external_single_structure(
 612                 array(
 613                     'item' => new external_value(PARAM_TEXT, $itemdesc, VALUE_OPTIONAL),
 614                     'itemid' => new external_value(PARAM_INT, $itemiddesc, VALUE_OPTIONAL),
 615                     'warningcode' => new external_value(PARAM_ALPHANUM, $warningcodedesc),
 616                     'message' => new external_value(PARAM_TEXT,
 617                             'untranslated english message to explain the warning')
 618                 ), 'warning'),
 619             'list of warnings', VALUE_OPTIONAL);
 620     }
 621 }
 622
 623 /**
 624  * A pre-filled external_value class for text format.
 625  *
 626  * Default is FORMAT_HTML
 627  * This should be used all the time in external xxx_params()/xxx_returns functions
 628  * as it is the standard way to implement text format param/return values.
 629  *
 630  * @package    core_webservice
 631  * @copyright  2012 Jerome Mouneyrac
 632  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 633  * @since Moodle 2.3
 634  */
 635 class external_format_value extends external_value {
 636
 637     /**
 638      * Constructor
 639      *
 640      * @param string $textfieldname Name of the text field
 641      * @param int $required if VALUE_REQUIRED then set standard default FORMAT_HTML
 642      * @since Moodle 2.3
 643      */
 644     public function __construct($textfieldname, $required = VALUE_REQUIRED) {
 645
 646         $default = ($required == VALUE_DEFAULT) ? FORMAT_HTML : null;
 647
 648         $desc = $textfieldname . ' format (' . FORMAT_HTML . ' = HTML, '
 649                 . FORMAT_MOODLE . ' = MOODLE, '
 650                 . FORMAT_PLAIN . ' = PLAIN or '
 651                 . FORMAT_MARKDOWN . ' = MARKDOWN)';
 652
 653         parent::__construct(PARAM_INT, $desc, $required, $default);
 654     }
 655 }
 656
 657 /**
 658  * Validate text field format against known FORMAT_XXX
 659  *
 660  * @param array $format the format to validate
 661  * @return the validated format
 662  * @throws coding_exception
 663  * @since 2.3
 664  */
 665 function external_validate_format($format) {
 666     $allowedformats = array(FORMAT_HTML, FORMAT_MOODLE, FORMAT_PLAIN, FORMAT_MARKDOWN);
 667     if (!in_array($format, $allowedformats)) {
 668         throw new moodle_exception('formatnotsupported', 'webservice', '' , null,
 669                 'The format with value=' . $format . ' is not supported by this Moodle site');
 670     }
 671     return $format;
 672 }
 673
 674 /**
 675  * Format the text to be returned properly as requested by the either the web service server,
 676  * either by an internally call.
 677  * The caller can change the format (raw, filter, file, fileurl) with the external_settings singleton
 678  * All web service servers must set this singleton when parsing the $_GET and $_POST.
 679  *
 680  * @param string $text The content that may contain ULRs in need of rewriting.
 681  * @param int $textformat The text format, by default FORMAT_HTML.
 682  * @param int $contextid This parameter and the next two identify the file area to use.
 683  * @param string $component
 684  * @param string $filearea helps identify the file area.
 685  * @param int $itemid helps identify the file area.
 686  * @return array text + textformat
 687  * @since Moodle 2.3
 688  */
 689 function external_format_text($text, $textformat, $contextid, $component, $filearea, $itemid) {
 690     global $CFG;
 691
 692     // Get settings (singleton).
 693     $settings = external_settings::get_instance();
 694
 695     if ($settings->get_fileurl()) {
 696         require_once($CFG->libdir . "/filelib.php");
 697         $text = file_rewrite_pluginfile_urls($text, $settings->get_file(), $contextid, $component, $filearea, $itemid);
 698     }
 699
 700     if (!$settings->get_raw()) {
 701         $textformat = FORMAT_HTML; // Force format to HTML when not raw.
 702         $text = format_text($text, $textformat,
 703                 array('noclean' => true, 'para' => false, 'filter' => $settings->get_filter()));
 704     }
 705
 706     return array($text, $textformat);
 707 }
 708
 709 /**
 710  * Singleton to handle the external settings.
 711  *
 712  * We use singleton to encapsulate the "logic"
 713  *
 714  * @package    core_webservice
 715  * @copyright  2012 Jerome Mouneyrac
 716  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 717  * @since Moodle 2.3
 718  */
 719 class external_settings {
 720
 721     /** @var object the singleton instance */
 722     public static $instance = null;
 723
 724     /** @var boolean Should the external function return raw text or formatted */
 725     private $raw = false;
 726
 727     /** @var boolean Should the external function filter the text */
 728     private $filter = false;
 729
 730     /** @var boolean Should the external function rewrite plugin file url */
 731     private $fileurl = true;
 732
 733     /** @var string In which file should the urls be rewritten */
 734     private $file = 'webservice/pluginfile.php';
 735
 736     /**
 737      * Constructor - protected - can not be instanciated
 738      */
 739     protected function __construct() {
 740     }
 741
 742     /**
 743      * Clone - private - can not be cloned
 744      */
 745     private final function __clone() {
 746     }
 747
 748     /**
 749      * Return only one instance
 750      *
 751      * @return object
 752      */
 753     public static function get_instance() {
 754         if (self::$instance === null) {
 755             self::$instance = new external_settings;
 756         }
 757
 758         return self::$instance;
 759     }
 760
 761     /**
 762      * Set raw
 763      *
 764      * @param boolean $raw
 765      */
 766     public function set_raw($raw) {
 767         $this->raw = $raw;
 768     }
 769
 770     /**
 771      * Get raw
 772      *
 773      * @return boolean
 774      */
 775     public function get_raw() {
 776         return $this->raw;
 777     }
 778
 779     /**
 780      * Set filter
 781      *
 782      * @param boolean $filter
 783      */
 784     public function set_filter($filter) {
 785         $this->filter = $filter;
 786     }
 787
 788     /**
 789      * Get filter
 790      *
 791      * @return boolean
 792      */
 793     public function get_filter() {
 794         return $this->filter;
 795     }
 796
 797     /**
 798      * Set fileurl
 799      *
 800      * @param boolean $fileurl
 801      */
 802     public function set_fileurl($fileurl) {
 803         $this->fileurl = $fileurl;
 804     }
 805
 806     /**
 807      * Get fileurl
 808      *
 809      * @return boolean
 810      */
 811     public function get_fileurl() {
 812         return $this->fileurl;
 813     }
 814
 815     /**
 816      * Set file
 817      *
 818      * @param string $file
 819      */
 820     public function set_file($file) {
 821         $this->file = $file;
 822     }
 823
 824     /**
 825      * Get file
 826      *
 827      * @return string
 828      */
 829     public function get_file() {
 830         return $this->file;
 831     }
 832 }