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     }
  93
  94     return $function;
  95 }
  96
  97 /**
  98  * Exception indicating user is not allowed to use external function in
  99  * the current context.
 100  */
 101 class restricted_context_exception extends moodle_exception {
 102     /**
 103      * Constructor
 104      */
 105     function __construct() {
 106         parent::__construct('restrictedcontextexception', 'error');
 107     }
 108 }
 109
 110 /**
 111  * Base class for external api methods.
 112  */
 113 class external_api {
 114     private static $contextrestriction;
 115
 116     /**
 117      * Set context restriction for all following subsequent function calls.
 118      * @param stdClass $contex
 119      * @return void
 120      */
 121     public static function set_context_restriction($context) {
 122         self::$contextrestriction = $context;
 123     }
 124
 125     /**
 126      * This method has to be called before every operation
 127      * that takes a longer time to finish!
 128      *
 129      * @param int $seconds max expected time the next operation needs
 130      * @return void
 131      */
 132     public static function set_timeout($seconds=360) {
 133         $seconds = ($seconds < 300) ? 300 : $seconds;
 134         set_time_limit($seconds);
 135     }
 136
 137     /**
 138      * Validates submitted function parameters, if anything is incorrect
 139      * invalid_parameter_exception is thrown.
 140      * This is a simple recursive method which is intended to be called from
 141      * each implementation method of external API.
 142      * @param external_description $description description of parameters
 143      * @param mixed $params the actual parameters
 144      * @return mixed params with added defaults for optional items, invalid_parameters_exception thrown if any problem found
 145      */
 146     public static function validate_parameters(external_description $description, $params) {
 147         if ($description instanceof external_value) {
 148             if (is_array($params) or is_object($params)) {
 149                 throw new invalid_parameter_exception(get_string('errorscalartype', 'webservice'));
 150             }
 151
 152             if ($description->type == PARAM_BOOL) {
 153                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 154                 if (is_bool($params) or $params === 0 or $params === 1 or $params === '0' or $params === '1') {
 155                     return (bool)$params;
 156                 }
 157             }
 158             return validate_param($params, $description->type, $description->allownull, get_string('errorinvalidparamsapi', 'webservice'));
 159
 160         } else if ($description instanceof external_single_structure) {
 161             if (!is_array($params)) {
 162                 throw new invalid_parameter_exception(get_string('erroronlyarray', 'webservice'));
 163             }
 164             $result = array();
 165             foreach ($description->keys as $key=>$subdesc) {
 166                 if (!array_key_exists($key, $params)) {
 167                     if ($subdesc->required == VALUE_REQUIRED) {
 168                         throw new invalid_parameter_exception(get_string('errormissingkey', 'webservice', $key));
 169                     }
 170                     if ($subdesc->required == VALUE_DEFAULT) {
 171                         try {
 172                             $result[$key] = self::validate_parameters($subdesc, $subdesc->default);
 173                         } catch (invalid_parameter_exception $e) {
 174                             throw new webservice_parameter_exception('invalidextparam',$key);
 175                         }
 176                     }
 177                 } else {
 178                     try {
 179                         $result[$key] = self::validate_parameters($subdesc, $params[$key]);
 180                     } catch (invalid_parameter_exception $e) {
 181                         //it's ok to display debug info as here the information is useful for ws client/dev
 182                         throw new webservice_parameter_exception('invalidextparam',$key." (".$e->debuginfo.")");
 183                     }
 184                 }
 185                 unset($params[$key]);
 186             }
 187             if (!empty($params)) {
 188                 //list all unexpected keys
 189                 $keys = '';
 190                 foreach($params as $key => $value) {
 191                     $keys .= $key . ',';
 192                 }
 193                 throw new invalid_parameter_exception(get_string('errorunexpectedkey', 'webservice', $keys));
 194             }
 195             return $result;
 196
 197         } else if ($description instanceof external_multiple_structure) {
 198             if (!is_array($params)) {
 199                 throw new invalid_parameter_exception(get_string('erroronlyarray', 'webservice'));
 200             }
 201             $result = array();
 202             foreach ($params as $param) {
 203                 $result[] = self::validate_parameters($description->content, $param);
 204             }
 205             return $result;
 206
 207         } else {
 208             throw new invalid_parameter_exception(get_string('errorinvalidparamsdesc', 'webservice'));
 209         }
 210     }
 211
 212     /**
 213      * Clean response
 214      * If a response attribute is unknown from the description, we just ignore the attribute.
 215      * If a response attribute is incorrect, invalid_response_exception is thrown.
 216      * Note: this function is similar to validate parameters, however it is distinct because
 217      * parameters validation must be distinct from cleaning return values.
 218      * @param external_description $description description of the return values
 219      * @param mixed $response the actual response
 220      * @return mixed response with added defaults for optional items, invalid_response_exception thrown if any problem found
 221      */
 222     public static function clean_returnvalue(external_description $description, $response) {
 223         if ($description instanceof external_value) {
 224             if (is_array($response) or is_object($response)) {
 225                 throw new invalid_response_exception(get_string('errorscalartype', 'webservice'));
 226             }
 227
 228             if ($description->type == PARAM_BOOL) {
 229                 // special case for PARAM_BOOL - we want true/false instead of the usual 1/0 - we can not be too strict here ;-)
 230                 if (is_bool($response) or $response === 0 or $response === 1 or $response === '0' or $response === '1') {
 231                     return (bool)$response;
 232                 }
 233             }
 234             return validate_param($response, $description->type, $description->allownull, get_string('errorinvalidresponseapi', 'webservice'));
 235
 236         } else if ($description instanceof external_single_structure) {
 237             if (!is_array($response)) {
 238                 throw new invalid_response_exception(get_string('erroronlyarray', 'webservice'));
 239             }
 240             $result = array();
 241             foreach ($description->keys as $key=>$subdesc) {
 242                 if (!array_key_exists($key, $response)) {
 243                     if ($subdesc->required == VALUE_REQUIRED) {
 244                         throw new webservice_parameter_exception('errorresponsemissingkey', $key);
 245                     }
 246                     if ($subdesc instanceof external_value) {
 247                         if ($subdesc->required == VALUE_DEFAULT) {
 248                             try {
 249                                     $result[$key] = self::clean_returnvalue($subdesc, $subdesc->default);
 250                             } catch (Exception $e) {
 251                                     throw new webservice_parameter_exception('invalidextresponse',$key." (".$e->debuginfo.")");
 252                             }
 253                         }
 254                     }
 255                 } else {
 256                     try {
 257                         $result[$key] = self::clean_returnvalue($subdesc, $response[$key]);
 258                     } catch (Exception $e) {
 259                         //it's ok to display debug info as here the information is useful for ws client/dev
 260                         throw new webservice_parameter_exception('invalidextresponse',$key." (".$e->debuginfo.")");
 261                     }
 262                 }
 263                 unset($response[$key]);
 264             }
 265
 266             return $result;
 267
 268         } else if ($description instanceof external_multiple_structure) {
 269             if (!is_array($response)) {
 270                 throw new invalid_response_exception(get_string('erroronlyarray', 'webservice'));
 271             }
 272             $result = array();
 273             foreach ($response as $param) {
 274                 $result[] = self::clean_returnvalue($description->content, $param);
 275             }
 276             return $result;
 277
 278         } else {
 279             throw new invalid_response_exception(get_string('errorinvalidresponsedesc', 'webservice'));
 280         }
 281     }
 282
 283     /**
 284      * Makes sure user may execute functions in this context.
 285      * @param object $context
 286      * @return void
 287      */
 288     protected static function validate_context($context) {
 289         global $CFG;
 290
 291         if (empty($context)) {
 292             throw new invalid_parameter_exception('Context does not exist');
 293         }
 294         if (empty(self::$contextrestriction)) {
 295             self::$contextrestriction = get_context_instance(CONTEXT_SYSTEM);
 296         }
 297         $rcontext = self::$contextrestriction;
 298
 299         if ($rcontext->contextlevel == $context->contextlevel) {
 300             if ($rcontext->id != $context->id) {
 301                 throw new restricted_context_exception();
 302             }
 303         } else if ($rcontext->contextlevel > $context->contextlevel) {
 304             throw new restricted_context_exception();
 305         } else {
 306             $parents = get_parent_contexts($context);
 307             if (!in_array($rcontext->id, $parents)) {
 308                 throw new restricted_context_exception();
 309             }
 310         }
 311
 312         if ($context->contextlevel >= CONTEXT_COURSE) {
 313             list($context, $course, $cm) = get_context_info_array($context->id);
 314             require_login($course, false, $cm, false, true);
 315         }
 316     }
 317 }
 318
 319 /**
 320  * Common ancestor of all parameter description classes
 321  */
 322 abstract class external_description {
 323     /** @property string $description description of element */
 324     public $desc;
 325     /** @property bool $required element value required, null not allowed */
 326     public $required;
 327     /** @property mixed $default default value */
 328     public $default;
 329
 330     /**
 331      * Contructor
 332      * @param string $desc
 333      * @param bool $required
 334      * @param mixed $default
 335      */
 336     public function __construct($desc, $required, $default) {
 337         $this->desc = $desc;
 338         $this->required = $required;
 339         $this->default = $default;
 340     }
 341 }
 342
 343 /**
 344  * Scalar alue description class
 345  */
 346 class external_value extends external_description {
 347     /** @property mixed $type value type PARAM_XX */
 348     public $type;
 349     /** @property bool $allownull allow null values */
 350     public $allownull;
 351
 352     /**
 353      * Constructor
 354      * @param mixed $type
 355      * @param string $desc
 356      * @param bool $required
 357      * @param mixed $default
 358      * @param bool $allownull
 359      */
 360     public function __construct($type, $desc='', $required=VALUE_REQUIRED,
 361             $default=null, $allownull=NULL_ALLOWED) {
 362         parent::__construct($desc, $required, $default);
 363         $this->type      = $type;
 364         $this->allownull = $allownull;
 365     }
 366 }
 367
 368 /**
 369  * Associative array description class
 370  */
 371 class external_single_structure extends external_description {
 372      /** @property array $keys description of array keys key=>external_description */
 373     public $keys;
 374
 375     /**
 376      * Constructor
 377      * @param array $keys
 378      * @param string $desc
 379      * @param bool $required
 380      * @param array $default
 381      */
 382     public function __construct(array $keys, $desc='',
 383             $required=VALUE_REQUIRED, $default=null) {
 384         parent::__construct($desc, $required, $default);
 385         $this->keys = $keys;
 386     }
 387 }
 388
 389 /**
 390  * Bulk array description class.
 391  */
 392 class external_multiple_structure extends external_description {
 393      /** @property external_description $content */
 394     public $content;
 395
 396     /**
 397      * Constructor
 398      * @param external_description $content
 399      * @param string $desc
 400      * @param bool $required
 401      * @param array $default
 402      */
 403     public function __construct(external_description $content, $desc='',
 404             $required=VALUE_REQUIRED, $default=null) {
 405         parent::__construct($desc, $required, $default);
 406         $this->content = $content;
 407     }
 408 }
 409
 410 /**
 411  * Description of top level - PHP function parameters.
 412  * @author skodak
 413  *
 414  */
 415 class external_function_parameters extends external_single_structure {
 416 }
 417
 418 function external_generate_token($tokentype, $serviceorid, $userid, $contextorid, $validuntil=0, $iprestriction=''){
 419     global $DB, $USER;
 420     // make sure the token doesn't exist (even if it should be almost impossible with the random generation)
 421     $numtries = 0;
 422     do {
 423         $numtries ++;
 424         $generatedtoken = md5(uniqid(rand(),1));
 425         if ($numtries > 5){
 426             throw new moodle_exception('tokengenerationfailed');
 427         }
 428     } while ($DB->record_exists('external_tokens', array('token'=>$generatedtoken)));
 429     $newtoken = new stdClass();
 430     $newtoken->token = $generatedtoken;
 431     if (!is_object($serviceorid)){
 432         $service = $DB->get_record('external_services', array('id' => $serviceorid));
 433     } else {
 434         $service = $serviceorid;
 435     }
 436     if (!is_object($contextorid)){
 437         $context = get_context_instance_by_id($contextorid, MUST_EXIST);
 438     } else {
 439         $context = $contextorid;
 440     }
 441     if (empty($service->requiredcapability) || has_capability($service->requiredcapability, $context, $userid)) {
 442         $newtoken->externalserviceid = $service->id;
 443     } else {
 444         throw new moodle_exception('nocapabilitytousethisservice');
 445     }
 446     $newtoken->tokentype = $tokentype;
 447     $newtoken->userid = $userid;
 448     if ($tokentype == EXTERNAL_TOKEN_EMBEDDED){
 449         $newtoken->sid = session_id();
 450     }
 451
 452     $newtoken->contextid = $context->id;
 453     $newtoken->creatorid = $USER->id;
 454     $newtoken->timecreated = time();
 455     $newtoken->validuntil = $validuntil;
 456     if (!empty($iprestriction)) {
 457         $newtoken->iprestriction = $iprestriction;
 458     }
 459     $DB->insert_record('external_tokens', $newtoken);
 460     return $newtoken->token;
 461 }
 462 /**
 463  * Create and return a session linked token. Token to be used for html embedded client apps that want to communicate
 464  * with the Moodle server through web services. The token is linked to the current session for the current page request.
 465  * It is expected this will be called in the script generating the html page that is embedding the client app and that the
 466  * returned token will be somehow passed into the client app being embedded in the page.
 467  * @param string $servicename name of the web service. Service name as defined in db/services.php
 468  * @param int $context context within which the web service can operate.
 469  * @return int returns token id.
 470  */
 471 function external_create_service_token($servicename, $context){
 472     global $USER, $DB;
 473     $service = $DB->get_record('external_services', array('name'=>$servicename), '*', MUST_EXIST);
 474     return external_generate_token(EXTERNAL_TOKEN_EMBEDDED, $service, $USER->id, $context, 0);
 475 }