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)) {
 270                 throw new invalid_response_exception('Only arrays accepted. The bad value is: \'' .
 271                         print_r($response, true) . '\'');
 272             }
 273             $result = array();
 274             foreach ($description->keys as $key=>$subdesc) {
 275                 if (!array_key_exists($key, $response)) {
 276                     if ($subdesc->required == VALUE_REQUIRED) {
 277                         throw new invalid_response_exception('Error in response - Missing following required key in a single structure: ' . $key);
 278                     }
 279                     if ($subdesc instanceof external_value) {
 280                         if ($subdesc->required == VALUE_DEFAULT) {
 281                             try {
 282                                     $result[$key] = self::clean_returnvalue($subdesc, $subdesc->default);
 283                             } catch (invalid_response_exception $e) {
 284                                 //build the path to the faulty attribut
 285                                 throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 286                             }
 287                         }
 288                     }
 289                 } else {
 290                     try {
 291                         $result[$key] = self::clean_returnvalue($subdesc, $response[$key]);
 292                     } catch (invalid_response_exception $e) {
 293                         //build the path to the faulty attribut
 294                         throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 295                     }
 296                 }
 297                 unset($response[$key]);
 298             }
 299
 300             return $result;
 301
 302         } else if ($description instanceof external_multiple_structure) {
 303             if (!is_array($response)) {
 304                 throw new invalid_response_exception('Only arrays accepted. The bad value is: \'' .
 305                         print_r($response, true) . '\'');
 306             }
 307             $result = array();
 308             foreach ($response as $param) {
 309                 $result[] = self::clean_returnvalue($description->content, $param);
 310             }
 311             return $result;
 312
 313         } else {
 314             throw new invalid_response_exception('Invalid external api response description');
 315         }
 316     }
 317
 318     /**
 319      * Makes sure user may execute functions in this context.
 320      *
 321      * @param stdClass $context
 322      * @since Moodle 2.0
 323      */
 324     protected static function validate_context($context) {
 325         global $CFG;
 326
 327         if (empty($context)) {
 328             throw new invalid_parameter_exception('Context does not exist');
 329         }
 330         if (empty(self::$contextrestriction)) {
 331             self::$contextrestriction = get_context_instance(CONTEXT_SYSTEM);
 332         }
 333         $rcontext = self::$contextrestriction;
 334
 335         if ($rcontext->contextlevel == $context->contextlevel) {
 336             if ($rcontext->id != $context->id) {
 337                 throw new restricted_context_exception();
 338             }
 339         } else if ($rcontext->contextlevel > $context->contextlevel) {
 340             throw new restricted_context_exception();
 341         } else {
 342             $parents = get_parent_contexts($context);
 343             if (!in_array($rcontext->id, $parents)) {
 344                 throw new restricted_context_exception();
 345             }
 346         }
 347
 348         if ($context->contextlevel >= CONTEXT_COURSE) {
 349             list($context, $course, $cm) = get_context_info_array($context->id);
 350             require_login($course, false, $cm, false, true);
 351         }
 352     }
 353 }
 354
 355 /**
 356  * Common ancestor of all parameter description classes
 357  *
 358  * @package    core_webservice
 359  * @copyright  2009 Petr Skodak
 360  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 361  * @since Moodle 2.0
 362  */
 363 abstract class external_description {
 364     /** @var string Description of element */
 365     public $desc;
 366
 367     /** @var bool Element value required, null not allowed */
 368     public $required;
 369
 370     /** @var mixed Default value */
 371     public $default;
 372
 373     /**
 374      * Contructor
 375      *
 376      * @param string $desc
 377      * @param bool $required
 378      * @param mixed $default
 379      * @since Moodle 2.0
 380      */
 381     public function __construct($desc, $required, $default) {
 382         $this->desc = $desc;
 383         $this->required = $required;
 384         $this->default = $default;
 385     }
 386 }
 387
 388 /**
 389  * Scalar value description class
 390  *
 391  * @package    core_webservice
 392  * @copyright  2009 Petr Skodak
 393  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 394  * @since Moodle 2.0
 395  */
 396 class external_value extends external_description {
 397
 398     /** @var mixed Value type PARAM_XX */
 399     public $type;
 400
 401     /** @var bool Allow null values */
 402     public $allownull;
 403
 404     /**
 405      * Constructor
 406      *
 407      * @param mixed $type
 408      * @param string $desc
 409      * @param bool $required
 410      * @param mixed $default
 411      * @param bool $allownull
 412      * @since Moodle 2.0
 413      */
 414     public function __construct($type, $desc='', $required=VALUE_REQUIRED,
 415             $default=null, $allownull=NULL_ALLOWED) {
 416         parent::__construct($desc, $required, $default);
 417         $this->type      = $type;
 418         $this->allownull = $allownull;
 419     }
 420 }
 421
 422 /**
 423  * Associative array description class
 424  *
 425  * @package    core_webservice
 426  * @copyright  2009 Petr Skodak
 427  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 428  * @since Moodle 2.0
 429  */
 430 class external_single_structure extends external_description {
 431
 432      /** @var array Description of array keys key=>external_description */
 433     public $keys;
 434
 435     /**
 436      * Constructor
 437      *
 438      * @param array $keys
 439      * @param string $desc
 440      * @param bool $required
 441      * @param array $default
 442      * @since Moodle 2.0
 443      */
 444     public function __construct(array $keys, $desc='',
 445             $required=VALUE_REQUIRED, $default=null) {
 446         parent::__construct($desc, $required, $default);
 447         $this->keys = $keys;
 448     }
 449 }
 450
 451 /**
 452  * Bulk array description class.
 453  *
 454  * @package    core_webservice
 455  * @copyright  2009 Petr Skodak
 456  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 457  * @since Moodle 2.0
 458  */
 459 class external_multiple_structure extends external_description {
 460
 461      /** @var external_description content */
 462     public $content;
 463
 464     /**
 465      * Constructor
 466      *
 467      * @param external_description $content
 468      * @param string $desc
 469      * @param bool $required
 470      * @param array $default
 471      * @since Moodle 2.0
 472      */
 473     public function __construct(external_description $content, $desc='',
 474             $required=VALUE_REQUIRED, $default=null) {
 475         parent::__construct($desc, $required, $default);
 476         $this->content = $content;
 477     }
 478 }
 479
 480 /**
 481  * Description of top level - PHP function parameters.
 482  *
 483  * @package    core_webservice
 484  * @copyright  2009 Petr Skodak
 485  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 486  * @since Moodle 2.0
 487  */
 488 class external_function_parameters extends external_single_structure {
 489 }
 490
 491 /**
 492  * Generate a token
 493  *
 494  * @param string $tokentype EXTERNAL_TOKEN_EMBEDDED|EXTERNAL_TOKEN_PERMANENT
 495  * @param stdClass|int $serviceorid service linked to the token
 496  * @param int $userid user linked to the token
 497  * @param stdClass|int $contextorid
 498  * @param int $validuntil date when the token expired
 499  * @param string $iprestriction allowed ip - if 0 or empty then all ips are allowed
 500  * @return string generated token
 501  * @author  2010 Jamie Pratt
 502  * @since Moodle 2.0
 503  */
 504 function external_generate_token($tokentype, $serviceorid, $userid, $contextorid, $validuntil=0, $iprestriction=''){
 505     global $DB, $USER;
 506     // make sure the token doesn't exist (even if it should be almost impossible with the random generation)
 507     $numtries = 0;
 508     do {
 509         $numtries ++;
 510         $generatedtoken = md5(uniqid(rand(),1));
 511         if ($numtries > 5){
 512             throw new moodle_exception('tokengenerationfailed');
 513         }
 514     } while ($DB->record_exists('external_tokens', array('token'=>$generatedtoken)));
 515     $newtoken = new stdClass();
 516     $newtoken->token = $generatedtoken;
 517     if (!is_object($serviceorid)){
 518         $service = $DB->get_record('external_services', array('id' => $serviceorid));
 519     } else {
 520         $service = $serviceorid;
 521     }
 522     if (!is_object($contextorid)){
 523         $context = get_context_instance_by_id($contextorid, MUST_EXIST);
 524     } else {
 525         $context = $contextorid;
 526     }
 527     if (empty($service->requiredcapability) || has_capability($service->requiredcapability, $context, $userid)) {
 528         $newtoken->externalserviceid = $service->id;
 529     } else {
 530         throw new moodle_exception('nocapabilitytousethisservice');
 531     }
 532     $newtoken->tokentype = $tokentype;
 533     $newtoken->userid = $userid;
 534     if ($tokentype == EXTERNAL_TOKEN_EMBEDDED){
 535         $newtoken->sid = session_id();
 536     }
 537
 538     $newtoken->contextid = $context->id;
 539     $newtoken->creatorid = $USER->id;
 540     $newtoken->timecreated = time();
 541     $newtoken->validuntil = $validuntil;
 542     if (!empty($iprestriction)) {
 543         $newtoken->iprestriction = $iprestriction;
 544     }
 545     $DB->insert_record('external_tokens', $newtoken);
 546     return $newtoken->token;
 547 }
 548
 549 /**
 550  * Create and return a session linked token. Token to be used for html embedded client apps that want to communicate
 551  * with the Moodle server through web services. The token is linked to the current session for the current page request.
 552  * It is expected this will be called in the script generating the html page that is embedding the client app and that the
 553  * returned token will be somehow passed into the client app being embedded in the page.
 554  *
 555  * @param string $servicename name of the web service. Service name as defined in db/services.php
 556  * @param int $context context within which the web service can operate.
 557  * @return int returns token id.
 558  * @since Moodle 2.0
 559  */
 560 function external_create_service_token($servicename, $context){
 561     global $USER, $DB;
 562     $service = $DB->get_record('external_services', array('name'=>$servicename), '*', MUST_EXIST);
 563     return external_generate_token(EXTERNAL_TOKEN_EMBEDDED, $service, $USER->id, $context, 0);
 564 }
 565
 566 /**
 567  * Delete all pre-built services (+ related tokens) and external functions information defined in the specified component.
 568  *
 569  * @param string $component name of component (moodle, mod_assignment, etc.)
 570  */
 571 function external_delete_descriptions($component) {
 572     global $DB;
 573
 574     $params = array($component);
 575
 576     $DB->delete_records_select('external_tokens',
 577             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 578     $DB->delete_records_select('external_services_users',
 579             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 580     $DB->delete_records_select('external_services_functions',
 581             "functionname IN (SELECT name FROM {external_functions} WHERE component = ?)", $params);
 582     $DB->delete_records('external_services', array('component'=>$component));
 583     $DB->delete_records('external_functions', array('component'=>$component));
 584 }