lib/externallib.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 /**
  19  * Support for external API
  20  *
  21  * @package    core
  22  * @subpackage webservice
  23  * @copyright  2009 Moodle Pty Ltd (http://moodle.com)
  24  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25  */
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 /**
  30  * Returns detailed function information
  31  * @param string|object $function name of external function or record from external_function
  32  * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
  33  *                        MUST_EXIST means throw exception if no record or multiple records found
  34  * @return object description or false if not found or exception thrown
  35  */
  36 function external_function_info($function, $strictness=MUST_EXIST) {
  37     global $DB, $CFG;
  38
  39     if (!is_object($function)) {
  40         if (!$function = $DB->get_record('external_functions', array('name'=>$function), '*', $strictness)) {
  41             return false;
  42         }
  43     }
  44
  45     //first find and include the ext implementation class
  46     $function->classpath = empty($function->classpath) ? get_component_directory($function->component).'/externallib.php' : $CFG->dirroot.'/'.$function->classpath;
  47     if (!file_exists($function->classpath)) {
  48         throw new coding_exception('Can not find file with external function implementation');
  49     }
  50     require_once($function->classpath);
  51
  52     $function->parameters_method = $function->methodname.'_parameters';
  53     $function->returns_method    = $function->methodname.'_returns';
  54
  55     // make sure the implementaion class is ok
  56     if (!method_exists($function->classname, $function->methodname)) {
  57         throw new coding_exception('Missing implementation method of '.$function->classname.'::'.$function->methodname);
  58     }
  59     if (!method_exists($function->classname, $function->parameters_method)) {
  60         throw new coding_exception('Missing parameters description');
  61     }
  62     if (!method_exists($function->classname, $function->returns_method)) {
  63         throw new coding_exception('Missing returned values description');
  64     }
  65
  66     // fetch the parameters description
  67     $function->parameters_desc = call_user_func(array($function->classname, $function->parameters_method));
  68     if (!($function->parameters_desc instanceof external_function_parameters)) {
  69         throw new coding_exception('Invalid parameters description');
  70     }
  71
  72     // fetch the return values description
  73     $function->returns_desc = call_user_func(array($function->classname, $function->returns_method));
  74     // null means void result or result is ignored
  75     if (!is_null($function->returns_desc) and !($function->returns_desc instanceof external_description)) {
  76         throw new coding_exception('Invalid return description');
  77     }
  78
  79     //now get the function description
  80     //TODO: use localised lang pack descriptions, it would be nice to have
  81     //      easy to understand descriptions in admin UI,
  82     //      on the other hand this is still a bit in a flux and we need to find some new naming
  83     //      conventions for these descriptions in lang packs
  84     $function->description = null;
  85     $servicesfile = get_component_directory($function->component).'/db/services.php';
  86     if (file_exists($servicesfile)) {
  87         $functions = null;
  88         include($servicesfile);
  89         if (isset($functions[$function->name]['description'])) {
  90             $function->description = $functions[$function->name]['description'];
  91         }
  92         if (isset($functions[$function->name]['testclientpath'])) {
  93             $function->testclientpath = $functions[$function->name]['testclientpath'];
  94         }
  95     }
  96
  97     return $function;
  98 }
  99
 100 /**
 101  * Exception indicating user is not allowed to use external function in
 102  * the current context.
 103  */
 104 class restricted_context_exception extends moodle_exception {
 105     /**
 106      * Constructor
 107      */
 108     function __construct() {
 109         parent::__construct('restrictedcontextexception', 'error');
 110     }
 111 }
 112
 113 /**
 114  * Base class for external api methods.
 115  */
 116 class external_api {
 117     private static $contextrestriction;
 118
 119     /**
 120      * Set context restriction for all following subsequent function calls.
 121      * @param stdClass $contex
 122      * @return void
 123      */
 124     public static function set_context_restriction($context) {
 125         self::$contextrestriction = $context;
 126     }
 127
 128     /**
 129      * This method has to be called before every operation
 130      * that takes a longer time to finish!
 131      *
 132      * @param int $seconds max expected time the next operation needs
 133      * @return void
 134      */
 135     public static function set_timeout($seconds=360) {
 136         $seconds = ($seconds < 300) ? 300 : $seconds;
 137         set_time_limit($seconds);
 138     }
 139
 140     /**
 141      * Validates submitted function parameters, if anything is incorrect
 142      * invalid_parameter_exception is thrown.
 143      * This is a simple recursive method which is intended to be called from
 144      * each implementation method of external API.
 145      * @param external_description $description description of parameters
 146      * @param mixed $params the actual parameters
 147      * @return mixed params with added defaults for optional items, invalid_parameters_exception thrown if any problem found
 148      */
 149     public static function validate_parameters(external_description $description, $params) {
 150         if ($description instanceof external_value) {
 151             if (is_array($params) or is_object($params)) {
 152                 throw new invalid_parameter_exception('Scalar type expected, array or object received.');
 153             }
 154
 155             if ($description->type == PARAM_BOOL) {
 156                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 157                 if (is_bool($params) or $params === 0 or $params === 1 or $params === '0' or $params === '1') {
 158                     return (bool)$params;
 159                 }
 160             }
 161             $debuginfo = 'Invalid external api parameter: the value is "' . $params .
 162                     '", the server was expecting "' . $description->type . '" type';
 163             return validate_param($params, $description->type, $description->allownull, $debuginfo);
 164
 165         } else if ($description instanceof external_single_structure) {
 166             if (!is_array($params)) {
 167                 throw new invalid_parameter_exception('Only arrays accepted. The bad value is: \''
 168                         . print_r($params, true) . '\'');
 169             }
 170             $result = array();
 171             foreach ($description->keys as $key=>$subdesc) {
 172                 if (!array_key_exists($key, $params)) {
 173                     if ($subdesc->required == VALUE_REQUIRED) {
 174                         throw new invalid_parameter_exception('Missing required key in single structure: '. $key);
 175                     }
 176                     if ($subdesc->required == VALUE_DEFAULT) {
 177                         try {
 178                             $result[$key] = self::validate_parameters($subdesc, $subdesc->default);
 179                         } catch (invalid_parameter_exception $e) {
 180                             //we are only interested by exceptions returned by validate_param() and validate_parameters()
 181                             //(in order to build the path to the faulty attribut)
 182                             throw new invalid_parameter_exception($key." => ".$e->getMessage() . ': ' .$e->debuginfo);
 183                         }
 184                     }
 185                 } else {
 186                     try {
 187                         $result[$key] = self::validate_parameters($subdesc, $params[$key]);
 188                     } catch (invalid_parameter_exception $e) {
 189                         //we are only interested by exceptions returned by validate_param() and validate_parameters()
 190                         //(in order to build the path to the faulty attribut)
 191                         throw new invalid_parameter_exception($key." => ".$e->getMessage() . ': ' .$e->debuginfo);
 192                     }
 193                 }
 194                 unset($params[$key]);
 195             }
 196             if (!empty($params)) {
 197                 throw new invalid_parameter_exception('Unexpected keys (' . implode(', ', array_keys($params)) . ') detected in parameter array.');
 198             }
 199             return $result;
 200
 201         } else if ($description instanceof external_multiple_structure) {
 202             if (!is_array($params)) {
 203                 throw new invalid_parameter_exception('Only arrays accepted. The bad value is: \''
 204                         . print_r($params, true) . '\'');
 205             }
 206             $result = array();
 207             foreach ($params as $param) {
 208                 $result[] = self::validate_parameters($description->content, $param);
 209             }
 210             return $result;
 211
 212         } else {
 213             throw new invalid_parameter_exception('Invalid external api description');
 214         }
 215     }
 216
 217     /**
 218      * Clean response
 219      * If a response attribute is unknown from the description, we just ignore the attribute.
 220      * If a response attribute is incorrect, invalid_response_exception is thrown.
 221      * Note: this function is similar to validate parameters, however it is distinct because
 222      * parameters validation must be distinct from cleaning return values.
 223      * @param external_description $description description of the return values
 224      * @param mixed $response the actual response
 225      * @return mixed response with added defaults for optional items, invalid_response_exception thrown if any problem found
 226      */
 227     public static function clean_returnvalue(external_description $description, $response) {
 228         if ($description instanceof external_value) {
 229             if (is_array($response) or is_object($response)) {
 230                 throw new invalid_response_exception('Scalar type expected, array or object received.');
 231             }
 232
 233             if ($description->type == PARAM_BOOL) {
 234                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 235                 if (is_bool($response) or $response === 0 or $response === 1 or $response === '0' or $response === '1') {
 236                     return (bool)$response;
 237                 }
 238             }
 239             $debuginfo = 'Invalid external api response: the value is "' . $response .
 240                     '", the server was expecting "' . $description->type . '" type';
 241             try {
 242                 return validate_param($response, $description->type, $description->allownull, $debuginfo);
 243             } catch (invalid_parameter_exception $e) {
 244                 //proper exception name, to be recursively catched to build the path to the faulty attribut
 245                 throw new invalid_response_exception($e->debuginfo);
 246             }
 247
 248         } else if ($description instanceof external_single_structure) {
 249             if (!is_array($response)) {
 250                 throw new invalid_response_exception('Only arrays accepted. The bad value is: \'' .
 251                         print_r($response, true) . '\'');
 252             }
 253             $result = array();
 254             foreach ($description->keys as $key=>$subdesc) {
 255                 if (!array_key_exists($key, $response)) {
 256                     if ($subdesc->required == VALUE_REQUIRED) {
 257                         throw new invalid_response_exception('Error in response - Missing following required key in a single structure: ' . $key);
 258                     }
 259                     if ($subdesc instanceof external_value) {
 260                         if ($subdesc->required == VALUE_DEFAULT) {
 261                             try {
 262                                     $result[$key] = self::clean_returnvalue($subdesc, $subdesc->default);
 263                             } catch (invalid_response_exception $e) {
 264                                 //build the path to the faulty attribut
 265                                 throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 266                             }
 267                         }
 268                     }
 269                 } else {
 270                     try {
 271                         $result[$key] = self::clean_returnvalue($subdesc, $response[$key]);
 272                     } catch (invalid_response_exception $e) {
 273                         //build the path to the faulty attribut
 274                         throw new invalid_response_exception($key." => ".$e->getMessage() . ': ' . $e->debuginfo);
 275                     }
 276                 }
 277                 unset($response[$key]);
 278             }
 279
 280             return $result;
 281
 282         } else if ($description instanceof external_multiple_structure) {
 283             if (!is_array($response)) {
 284                 throw new invalid_response_exception('Only arrays accepted. The bad value is: \'' .
 285                         print_r($response, true) . '\'');
 286             }
 287             $result = array();
 288             foreach ($response as $param) {
 289                 $result[] = self::clean_returnvalue($description->content, $param);
 290             }
 291             return $result;
 292
 293         } else {
 294             throw new invalid_response_exception('Invalid external api response description');
 295         }
 296     }
 297
 298     /**
 299      * Makes sure user may execute functions in this context.
 300      * @param object $context
 301      * @return void
 302      */
 303     protected static function validate_context($context) {
 304         global $CFG;
 305
 306         if (empty($context)) {
 307             throw new invalid_parameter_exception('Context does not exist');
 308         }
 309         if (empty(self::$contextrestriction)) {
 310             self::$contextrestriction = get_context_instance(CONTEXT_SYSTEM);
 311         }
 312         $rcontext = self::$contextrestriction;
 313
 314         if ($rcontext->contextlevel == $context->contextlevel) {
 315             if ($rcontext->id != $context->id) {
 316                 throw new restricted_context_exception();
 317             }
 318         } else if ($rcontext->contextlevel > $context->contextlevel) {
 319             throw new restricted_context_exception();
 320         } else {
 321             $parents = get_parent_contexts($context);
 322             if (!in_array($rcontext->id, $parents)) {
 323                 throw new restricted_context_exception();
 324             }
 325         }
 326
 327         if ($context->contextlevel >= CONTEXT_COURSE) {
 328             list($context, $course, $cm) = get_context_info_array($context->id);
 329             require_login($course, false, $cm, false, true);
 330         }
 331     }
 332 }
 333
 334 /**
 335  * Common ancestor of all parameter description classes
 336  */
 337 abstract class external_description {
 338     /** @property string $description description of element */
 339     public $desc;
 340     /** @property bool $required element value required, null not allowed */
 341     public $required;
 342     /** @property mixed $default default value */
 343     public $default;
 344
 345     /**
 346      * Contructor
 347      * @param string $desc
 348      * @param bool $required
 349      * @param mixed $default
 350      */
 351     public function __construct($desc, $required, $default) {
 352         $this->desc = $desc;
 353         $this->required = $required;
 354         $this->default = $default;
 355     }
 356 }
 357
 358 /**
 359  * Scalar alue description class
 360  */
 361 class external_value extends external_description {
 362     /** @property mixed $type value type PARAM_XX */
 363     public $type;
 364     /** @property bool $allownull allow null values */
 365     public $allownull;
 366
 367     /**
 368      * Constructor
 369      * @param mixed $type
 370      * @param string $desc
 371      * @param bool $required
 372      * @param mixed $default
 373      * @param bool $allownull
 374      */
 375     public function __construct($type, $desc='', $required=VALUE_REQUIRED,
 376             $default=null, $allownull=NULL_ALLOWED) {
 377         parent::__construct($desc, $required, $default);
 378         $this->type      = $type;
 379         $this->allownull = $allownull;
 380     }
 381 }
 382
 383 /**
 384  * Associative array description class
 385  */
 386 class external_single_structure extends external_description {
 387      /** @property array $keys description of array keys key=>external_description */
 388     public $keys;
 389
 390     /**
 391      * Constructor
 392      * @param array $keys
 393      * @param string $desc
 394      * @param bool $required
 395      * @param array $default
 396      */
 397     public function __construct(array $keys, $desc='',
 398             $required=VALUE_REQUIRED, $default=null) {
 399         parent::__construct($desc, $required, $default);
 400         $this->keys = $keys;
 401     }
 402 }
 403
 404 /**
 405  * Bulk array description class.
 406  */
 407 class external_multiple_structure extends external_description {
 408      /** @property external_description $content */
 409     public $content;
 410
 411     /**
 412      * Constructor
 413      * @param external_description $content
 414      * @param string $desc
 415      * @param bool $required
 416      * @param array $default
 417      */
 418     public function __construct(external_description $content, $desc='',
 419             $required=VALUE_REQUIRED, $default=null) {
 420         parent::__construct($desc, $required, $default);
 421         $this->content = $content;
 422     }
 423 }
 424
 425 /**
 426  * Description of top level - PHP function parameters.
 427  * @author skodak
 428  *
 429  */
 430 class external_function_parameters extends external_single_structure {
 431 }
 432
 433 function external_generate_token($tokentype, $serviceorid, $userid, $contextorid, $validuntil=0, $iprestriction=''){
 434     global $DB, $USER;
 435     // make sure the token doesn't exist (even if it should be almost impossible with the random generation)
 436     $numtries = 0;
 437     do {
 438         $numtries ++;
 439         $generatedtoken = md5(uniqid(rand(),1));
 440         if ($numtries > 5){
 441             throw new moodle_exception('tokengenerationfailed');
 442         }
 443     } while ($DB->record_exists('external_tokens', array('token'=>$generatedtoken)));
 444     $newtoken = new stdClass();
 445     $newtoken->token = $generatedtoken;
 446     if (!is_object($serviceorid)){
 447         $service = $DB->get_record('external_services', array('id' => $serviceorid));
 448     } else {
 449         $service = $serviceorid;
 450     }
 451     if (!is_object($contextorid)){
 452         $context = get_context_instance_by_id($contextorid, MUST_EXIST);
 453     } else {
 454         $context = $contextorid;
 455     }
 456     if (empty($service->requiredcapability) || has_capability($service->requiredcapability, $context, $userid)) {
 457         $newtoken->externalserviceid = $service->id;
 458     } else {
 459         throw new moodle_exception('nocapabilitytousethisservice');
 460     }
 461     $newtoken->tokentype = $tokentype;
 462     $newtoken->userid = $userid;
 463     if ($tokentype == EXTERNAL_TOKEN_EMBEDDED){
 464         $newtoken->sid = session_id();
 465     }
 466
 467     $newtoken->contextid = $context->id;
 468     $newtoken->creatorid = $USER->id;
 469     $newtoken->timecreated = time();
 470     $newtoken->validuntil = $validuntil;
 471     if (!empty($iprestriction)) {
 472         $newtoken->iprestriction = $iprestriction;
 473     }
 474     $DB->insert_record('external_tokens', $newtoken);
 475     return $newtoken->token;
 476 }
 477 /**
 478  * Create and return a session linked token. Token to be used for html embedded client apps that want to communicate
 479  * with the Moodle server through web services. The token is linked to the current session for the current page request.
 480  * It is expected this will be called in the script generating the html page that is embedding the client app and that the
 481  * returned token will be somehow passed into the client app being embedded in the page.
 482  * @param string $servicename name of the web service. Service name as defined in db/services.php
 483  * @param int $context context within which the web service can operate.
 484  * @return int returns token id.
 485  */
 486 function external_create_service_token($servicename, $context){
 487     global $USER, $DB;
 488     $service = $DB->get_record('external_services', array('name'=>$servicename), '*', MUST_EXIST);
 489     return external_generate_token(EXTERNAL_TOKEN_EMBEDDED, $service, $USER->id, $context, 0);
 490 }
 491
 492 /**
 493  * Delete all pre-built services (+ related tokens) and external functions information defined in the specified component.
 494  *
 495  * @param string $component name of component (moodle, mod_assignment, etc.)
 496  */
 497 function external_delete_descriptions($component) {
 498     global $DB;
 499
 500     $params = array($component);
 501
 502     $DB->delete_records_select('external_tokens',
 503             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 504     $DB->delete_records_select('external_services_users',
 505             "externalserviceid IN (SELECT id FROM {external_services} WHERE component = ?)", $params);
 506     $DB->delete_records_select('external_services_functions',
 507             "functionname IN (SELECT name FROM {external_functions} WHERE component = ?)", $params);
 508     $DB->delete_records('external_services', array('component'=>$component));
 509     $DB->delete_records('external_functions', array('component'=>$component));
 510 }