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(get_string('errorscalartype', 'webservice'));
 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             return validate_param($params, $description->type, $description->allownull, get_string('errorinvalidparamsapi', 'webservice'));
 162
 163         } else if ($description instanceof external_single_structure) {
 164             if (!is_array($params)) {
 165                 throw new invalid_parameter_exception(get_string('erroronlyarray', 'webservice'));
 166             }
 167             $result = array();
 168             foreach ($description->keys as $key=>$subdesc) {
 169                 if (!array_key_exists($key, $params)) {
 170                     if ($subdesc->required == VALUE_REQUIRED) {
 171                         throw new invalid_parameter_exception(get_string('errormissingkey', 'webservice', $key));
 172                     }
 173                     if ($subdesc->required == VALUE_DEFAULT) {
 174                         try {
 175                             $result[$key] = self::validate_parameters($subdesc, $subdesc->default);
 176                         } catch (invalid_parameter_exception $e) {
 177                             throw new webservice_parameter_exception('invalidextparam',$key);
 178                         }
 179                     }
 180                 } else {
 181                     try {
 182                         $result[$key] = self::validate_parameters($subdesc, $params[$key]);
 183                     } catch (invalid_parameter_exception $e) {
 184                         //it's ok to display debug info as here the information is useful for ws client/dev
 185                         throw new webservice_parameter_exception('invalidextparam',$key." (".$e->debuginfo.")");
 186                     }
 187                 }
 188                 unset($params[$key]);
 189             }
 190             if (!empty($params)) {
 191                 //list all unexpected keys
 192                 $keys = '';
 193                 foreach($params as $key => $value) {
 194                     $keys .= $key . ',';
 195                 }
 196                 throw new invalid_parameter_exception(get_string('errorunexpectedkey', 'webservice', $keys));
 197             }
 198             return $result;
 199
 200         } else if ($description instanceof external_multiple_structure) {
 201             if (!is_array($params)) {
 202                 throw new invalid_parameter_exception(get_string('erroronlyarray', 'webservice'));
 203             }
 204             $result = array();
 205             foreach ($params as $param) {
 206                 $result[] = self::validate_parameters($description->content, $param);
 207             }
 208             return $result;
 209
 210         } else {
 211             throw new invalid_parameter_exception(get_string('errorinvalidparamsdesc', 'webservice'));
 212         }
 213     }
 214
 215     /**
 216      * Clean response
 217      * If a response attribute is unknown from the description, we just ignore the attribute.
 218      * If a response attribute is incorrect, invalid_response_exception is thrown.
 219      * Note: this function is similar to validate parameters, however it is distinct because
 220      * parameters validation must be distinct from cleaning return values.
 221      * @param external_description $description description of the return values
 222      * @param mixed $response the actual response
 223      * @return mixed response with added defaults for optional items, invalid_response_exception thrown if any problem found
 224      */
 225     public static function clean_returnvalue(external_description $description, $response) {
 226         if ($description instanceof external_value) {
 227             if (is_array($response) or is_object($response)) {
 228                 throw new invalid_response_exception(get_string('errorscalartype', 'webservice'));
 229             }
 230
 231             if ($description->type == PARAM_BOOL) {
 232                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 233                 if (is_bool($response) or $response === 0 or $response === 1 or $response === '0' or $response === '1') {
 234                     return (bool)$response;
 235                 }
 236             }
 237             return validate_param($response, $description->type, $description->allownull, get_string('errorinvalidresponseapi', 'webservice'));
 238
 239         } else if ($description instanceof external_single_structure) {
 240             if (!is_array($response)) {
 241                 throw new invalid_response_exception(get_string('erroronlyarray', 'webservice'));
 242             }
 243             $result = array();
 244             foreach ($description->keys as $key=>$subdesc) {
 245                 if (!array_key_exists($key, $response)) {
 246                     if ($subdesc->required == VALUE_REQUIRED) {
 247                         throw new webservice_parameter_exception('errorresponsemissingkey', $key);
 248                     }
 249                     if ($subdesc instanceof external_value) {
 250                         if ($subdesc->required == VALUE_DEFAULT) {
 251                             try {
 252                                     $result[$key] = self::clean_returnvalue($subdesc, $subdesc->default);
 253                             } catch (Exception $e) {
 254                                     throw new webservice_parameter_exception('invalidextresponse',$key." (".$e->debuginfo.")");
 255                             }
 256                         }
 257                     }
 258                 } else {
 259                     try {
 260                         $result[$key] = self::clean_returnvalue($subdesc, $response[$key]);
 261                     } catch (Exception $e) {
 262                         //it's ok to display debug info as here the information is useful for ws client/dev
 263                         throw new webservice_parameter_exception('invalidextresponse',$key." (".$e->debuginfo.")");
 264                     }
 265                 }
 266                 unset($response[$key]);
 267             }
 268
 269             return $result;
 270
 271         } else if ($description instanceof external_multiple_structure) {
 272             if (!is_array($response)) {
 273                 throw new invalid_response_exception(get_string('erroronlyarray', 'webservice'));
 274             }
 275             $result = array();
 276             foreach ($response as $param) {
 277                 $result[] = self::clean_returnvalue($description->content, $param);
 278             }
 279             return $result;
 280
 281         } else {
 282             throw new invalid_response_exception(get_string('errorinvalidresponsedesc', 'webservice'));
 283         }
 284     }
 285
 286     /**
 287      * Makes sure user may execute functions in this context.
 288      * @param object $context
 289      * @return void
 290      */
 291     protected static function validate_context($context) {
 292         global $CFG;
 293
 294         if (empty($context)) {
 295             throw new invalid_parameter_exception('Context does not exist');
 296         }
 297         if (empty(self::$contextrestriction)) {
 298             self::$contextrestriction = get_context_instance(CONTEXT_SYSTEM);
 299         }
 300         $rcontext = self::$contextrestriction;
 301
 302         if ($rcontext->contextlevel == $context->contextlevel) {
 303             if ($rcontext->id != $context->id) {
 304                 throw new restricted_context_exception();
 305             }
 306         } else if ($rcontext->contextlevel > $context->contextlevel) {
 307             throw new restricted_context_exception();
 308         } else {
 309             $parents = get_parent_contexts($context);
 310             if (!in_array($rcontext->id, $parents)) {
 311                 throw new restricted_context_exception();
 312             }
 313         }
 314
 315         if ($context->contextlevel >= CONTEXT_COURSE) {
 316             list($context, $course, $cm) = get_context_info_array($context->id);
 317             require_login($course, false, $cm, false, true);
 318         }
 319     }
 320 }
 321
 322 /**
 323  * Common ancestor of all parameter description classes
 324  */
 325 abstract class external_description {
 326     /** @property string $description description of element */
 327     public $desc;
 328     /** @property bool $required element value required, null not allowed */
 329     public $required;
 330     /** @property mixed $default default value */
 331     public $default;
 332
 333     /**
 334      * Contructor
 335      * @param string $desc
 336      * @param bool $required
 337      * @param mixed $default
 338      */
 339     public function __construct($desc, $required, $default) {
 340         $this->desc = $desc;
 341         $this->required = $required;
 342         $this->default = $default;
 343     }
 344 }
 345
 346 /**
 347  * Scalar alue description class
 348  */
 349 class external_value extends external_description {
 350     /** @property mixed $type value type PARAM_XX */
 351     public $type;
 352     /** @property bool $allownull allow null values */
 353     public $allownull;
 354
 355     /**
 356      * Constructor
 357      * @param mixed $type
 358      * @param string $desc
 359      * @param bool $required
 360      * @param mixed $default
 361      * @param bool $allownull
 362      */
 363     public function __construct($type, $desc='', $required=VALUE_REQUIRED,
 364             $default=null, $allownull=NULL_ALLOWED) {
 365         parent::__construct($desc, $required, $default);
 366         $this->type      = $type;
 367         $this->allownull = $allownull;
 368     }
 369 }
 370
 371 /**
 372  * Associative array description class
 373  */
 374 class external_single_structure extends external_description {
 375      /** @property array $keys description of array keys key=>external_description */
 376     public $keys;
 377
 378     /**
 379      * Constructor
 380      * @param array $keys
 381      * @param string $desc
 382      * @param bool $required
 383      * @param array $default
 384      */
 385     public function __construct(array $keys, $desc='',
 386             $required=VALUE_REQUIRED, $default=null) {
 387         parent::__construct($desc, $required, $default);
 388         $this->keys = $keys;
 389     }
 390 }
 391
 392 /**
 393  * Bulk array description class.
 394  */
 395 class external_multiple_structure extends external_description {
 396      /** @property external_description $content */
 397     public $content;
 398
 399     /**
 400      * Constructor
 401      * @param external_description $content
 402      * @param string $desc
 403      * @param bool $required
 404      * @param array $default
 405      */
 406     public function __construct(external_description $content, $desc='',
 407             $required=VALUE_REQUIRED, $default=null) {
 408         parent::__construct($desc, $required, $default);
 409         $this->content = $content;
 410     }
 411 }
 412
 413 /**
 414  * Description of top level - PHP function parameters.
 415  * @author skodak
 416  *
 417  */
 418 class external_function_parameters extends external_single_structure {
 419 }
 420
 421 function external_generate_token($tokentype, $serviceorid, $userid, $contextorid, $validuntil=0, $iprestriction=''){
 422     global $DB, $USER;
 423     // make sure the token doesn't exist (even if it should be almost impossible with the random generation)
 424     $numtries = 0;
 425     do {
 426         $numtries ++;
 427         $generatedtoken = md5(uniqid(rand(),1));
 428         if ($numtries > 5){
 429             throw new moodle_exception('tokengenerationfailed');
 430         }
 431     } while ($DB->record_exists('external_tokens', array('token'=>$generatedtoken)));
 432     $newtoken = new stdClass();
 433     $newtoken->token = $generatedtoken;
 434     if (!is_object($serviceorid)){
 435         $service = $DB->get_record('external_services', array('id' => $serviceorid));
 436     } else {
 437         $service = $serviceorid;
 438     }
 439     if (!is_object($contextorid)){
 440         $context = get_context_instance_by_id($contextorid, MUST_EXIST);
 441     } else {
 442         $context = $contextorid;
 443     }
 444     if (empty($service->requiredcapability) || has_capability($service->requiredcapability, $context, $userid)) {
 445         $newtoken->externalserviceid = $service->id;
 446     } else {
 447         throw new moodle_exception('nocapabilitytousethisservice');
 448     }
 449     $newtoken->tokentype = $tokentype;
 450     $newtoken->userid = $userid;
 451     if ($tokentype == EXTERNAL_TOKEN_EMBEDDED){
 452         $newtoken->sid = session_id();
 453     }
 454
 455     $newtoken->contextid = $context->id;
 456     $newtoken->creatorid = $USER->id;
 457     $newtoken->timecreated = time();
 458     $newtoken->validuntil = $validuntil;
 459     if (!empty($iprestriction)) {
 460         $newtoken->iprestriction = $iprestriction;
 461     }
 462     $DB->insert_record('external_tokens', $newtoken);
 463     return $newtoken->token;
 464 }
 465 /**
 466  * Create and return a session linked token. Token to be used for html embedded client apps that want to communicate
 467  * with the Moodle server through web services. The token is linked to the current session for the current page request.
 468  * It is expected this will be called in the script generating the html page that is embedding the client app and that the
 469  * returned token will be somehow passed into the client app being embedded in the page.
 470  * @param string $servicename name of the web service. Service name as defined in db/services.php
 471  * @param int $context context within which the web service can operate.
 472  * @return int returns token id.
 473  */
 474 function external_create_service_token($servicename, $context){
 475     global $USER, $DB;
 476     $service = $DB->get_record('external_services', array('name'=>$servicename), '*', MUST_EXIST);
 477     return external_generate_token(EXTERNAL_TOKEN_EMBEDDED, $service, $USER->id, $context, 0);
 478 }