* @copyright Curverider Ltd 2008 * @link http://elgg.org/ */ // Result classes ///////////////////////////////////////////////////////////////////////// /** * @class GenericResult Result superclass. * @author Marcus Povey */ abstract class GenericResult { /** * The status of the result. * @var int */ private $status_code; /** * Message returned along with the status which is almost always an error message. * This must be human readable, understandable and localised. * @var string */ private $message; /** * Result store. * Attach result specific informaton here. * * @var mixed. Should probably be an object of some sort. */ private $result; /** * Set a status code and optional message. * * @param int $status The status code. * @param string $message The message. */ protected function setStatusCode($status, $message = "") { $this->status_code = $status; $this->message = $message; } /** * Set the result. * * @param mixed $result */ protected function setResult($result) { $this->result = $result; } protected function getStatusCode() { return $this->status_code; } protected function getStatusMessage() { return $this->message; } protected function getResult() { return $this->result; } /** * Serialise to a standard class. * * DEVNOTE: The API is only interested in data, we can not easily serialise * custom classes without the need for 1) the other side being PHP, 2) you need to have the class * definition installed, 3) its the right version! * * Therefore, I'm not bothering. * * Override this to include any more specific information, however api results should be attached to the * class using setResult(). * * if $CONFIG->debug is set then additional information about the runtime environment and authentication will be * returned. * * @return stdClass Object containing the serialised result. */ public function export() { global $ERRORS, $CONFIG, $PAM_HANDLER_MSG; $result = new stdClass; $result->status = $this->getStatusCode(); if ($this->getStatusMessage()!="") $result->message = $this->getStatusMessage(); $resultdata = $this->getResult(); if (isset($resultdata)) $result->result = $resultdata; if ((isset($CONFIG->debug)) && ($CONFIG->debug == true)) { if (count($ERRORS)) $result->runtime_errors = $ERRORS; if (count($PAM_HANDLER_MSG)) $result->pam = $PAM_HANDLER_MSG; } return $result; } } /** * @class SuccessResult * Generic success result class, extend if you want to do something special. * @author Marcus Povey */ class SuccessResult extends GenericResult { public static $RESULT_SUCCESS = 0; // Do not change this from 0 public function SuccessResult($result) { $this->setResult($result); $this->setStatusCode(SuccessResult::$RESULT_SUCCESS); } public static function getInstance($result) { // Return a new error object. return new SuccessResult($result); } } /** * @class ErrorResult * The error result class. * @author Marcus Povey */ class ErrorResult extends GenericResult { public static $RESULT_FAIL = -1 ; // Fail with no specific code public static $RESULT_FAIL_APIKEY_DISABLED = -30; public static $RESULT_FAIL_APIKEY_INACTIVE = -31; public static $RESULT_FAIL_APIKEY_INVALID = -32; public static $RESULT_FAIL_AUTHTOKEN = -20; // Invalid, expired or missing auth token public function ErrorResult($message, $code = "", Exception $exception = NULL) { if ($code == "") $code = GenericResult::$RESULT_FAIL; if ($exception!=NULL) $this->setResult($exception->__toString()); $this->setStatusCode($code, $message); } /** * Get a new instance of the ErrorResult. * * @param string $message * @param int $code * @param Exception $exception Optional exception for generating a stack trace. */ public static function getInstance($message, $code = "", Exception $exception = NULL) { // Return a new error object. return new ErrorResult($message, $code, $exception); } } // API Call functions ///////////////////////////////////////////////////////////////////// /** * An array holding methods. * The structure of this is * $METHODS = array ( * "api.method" => array ( * "function" = 'my_function_callback' * "call_method" = 'GET' | 'POST' * "parameters" = array ( * "variable" = array ( // NB, the order is the same as defined by your function callback * type => 'int' | 'bool' | 'float' | 'string' * required => true (default) | false * ) * ) * "require_auth" => true (default) | false * "description" => "Some human readable description" * ) * ) */ $METHODS = array(); /** * Get the request method. */ function get_call_method() { return $_SERVER['REQUEST_METHOD']; } /** * Validate a token against a given site. * * A token registered with one site can not be used from a different apikey(site), so be aware of this * during development. * * @param int $site The ID of the site * @param string $token The Token. * @return mixed The user id attached to the token or false. */ function validate_user_token($site, $token) { global $CONFIG; $site = (int)$site; $token = sanitise_string($token); if (!$site) throw new ConfigurationException("No site ID has been specified."); $time = time(); $user = get_data_row("SELECT * from {$CONFIG->dbprefix}users_apisessions where token='$token' and site_guid=$site and expires>$time"); if ($user) return $user->user_id; return false; } /** * Expose an arbitrary function as an api call. * * Limitations: Currently can not expose functions which expect objects or arrays. * * @param string $method The api name to expose this as, eg "myapi.dosomething" * @param string $function Your function callback. * @param array $parameters Optional list of parameters in the same order as in your function, with optional parameters last. * This array should be in the format * "variable" = array ( * type => 'int' | 'bool' | 'float' | 'string' | 'array' * required => true (default) | false * ) * @param string $call_method Define what call method should be used for this function. * @param bool $require_auth Whether this requires a user authentication token or not (default is true) * @param string $description Optional human readable description of the function. * @return bool */ function expose_function($method, $function, array $parameters = NULL, $call_method = "GET", $require_auth = true, $description = "") { global $METHODS; if ( ($method!="") && ($function!="") ) { $METHODS[$method] = array(); $METHODS[$method]["function"] = $function; if ($parameters!=NULL) $METHODS[$method]["parameters"] = $parameters; $call_method = strtoupper($call_method); switch ($call_method) { case 'POST' : $METHODS[$method]["call_method"] = 'POST'; break; case 'GET' : $METHODS[$method]["call_method"] = 'GET'; break; default : throw new InvalidParameterException("Unrecognised call method '$call_method'"); } $METHODS[$method]["description"] = $description; $METHODS[$method]["require_auth"] = $require_auth; return true; } return false; } /** * Executes a method. * A method is a function which you have previously exposed using expose_function. * * @param string $method Method, e.g. "foo.bar" * @param array $parameters Array of parameters in the format "variable" => "value", thse will be sanitised before being fed to your handler. * @param string $token The authentication token to authorise this method call. * @return GenericResult The result of the execution. * @throws APIException, SecurityException */ function execute_method($method, array $parameters, $token = "") { global $METHODS, $CONFIG; // Sanity check $method = sanitise_string($method); $token = sanitise_string($token); // See if we can find the method handler if ((isset($METHODS[$method]["function"])) && (is_callable($METHODS[$method]["function"]))) { // See if this is being made with the right call method if (strcmp(get_call_method(), $METHODS[$method]["call_method"])==0) { $serialised_parameters = ""; $validated_userid = validate_user_token($CONFIG->site_id, $token); if ((!$METHODS[$method]["require_auth"]) || ($validated_userid) || (isloggedin())) { // If we have parameters then we need to sanitise the parameters. if ((isset($METHODS[$method]["parameters"])) && (is_array($METHODS[$method]["parameters"]))) { foreach ($METHODS[$method]["parameters"] as $key => $value) { if ( (is_array($value)) // Check that this is an array && (isset($value['type'])) // Check we have a type defined ) { // Check that the variable is present in the request if ( (!isset($parameters[$key])) && // No parameter ((!isset($value['required'])) || ($value['required']!=true)) // and not optional ) throw new APIException("Missing parameter $key in method $method"); else { // Avoid debug error if (isset($parameters[$key])) { // Set variables casting to type. switch (strtolower($value['type'])) { case 'int': case 'integer' : $serialised_parameters .= "," . (int)trim($parameters[$key]); break; case 'bool': case 'boolean': if (strcasecmp(trim($parameters[$key]), "false")==0) $parameters[$key]=''; $serialised_parameters .= "," . (bool)trim($parameters[$key]); break; case 'string': $serialised_parameters .= ",'" . (string)mysql_real_escape_string(trim($parameters[$key])) . "'"; break; case 'float': $serialised_parameters .= "," . (float)trim($parameters[$key]); break; case 'array': $array = "array("; if (is_array($parameters[$key])) { foreach ($parameters[$key] as $k => $v) { $k = sanitise_string($k); $v = sanitise_string($v); $array .= "'$k'=>'$v',"; } $array = trim($array,","); } else throw APIException("$key does not appear to be an array."); $array .= ")"; $serialised_parameters .= $array; break; default : throw new APIException("Unrecognised type in cast {$value['type']} for variable '$key' in method '$method'"); } } } } else throw new APIException("Invalid parameter found for '$key' in method '$method'."); } } // Execute function: Construct function and calling parameters $function = $METHODS[$method]["function"]; $serialised_parameters = trim($serialised_parameters, ", "); $result = eval("return $function($serialised_parameters);"); // Sanity check result if ($result instanceof GenericResult) // If this function returns an api result itself, just return it return $result; if ($result === FALSE) throw new APIException("$function($serialised_parameters) has a parsing error."); if ($result === NULL) throw new APIException("$function($serialised_parameters) returned no value."); // If no value return SuccessResult::getInstance($result); // Otherwise assume that the call was successful and return it as a success object. } else throw new SecurityException("Authentication token either missing, invalid or expired.", GenericResult::$RESULT_FAIL_AUTHTOKEN); } else throw new CallException("$method must be called using '{$METHODS[$method]["call_method"]}'"); } // Return an error if not found throw new APIException("Method call '$method' has not been implemented."); } // System functions /////////////////////////////////////////////////////////////////////// /** * Simple api to return a list of all api's installed on the system. */ function list_all_apis() { global $METHODS; return $METHODS; } // Expose some system api functions expose_function("system.api.list", "list_all_apis", NULL, "GET", false, "List all available API calls on the system."); // PAM AUTH HMAC functions //////////////////////////////////////////////////////////////// /** * Map various algorithms to their PHP equivs. * This also gives us an easy way to disable algorithms. * * @param string $algo The algorithm * @return string The php algorithm * @throws APIException if an algorithm is not supported. */ function map_api_hash($algo) { $algo = strtolower(sanitise_string($algo)); $supported_algos = array( "md5" => "md5", // TODO: Consider phasing this out "sha" => "sha1", // alias for sha1 "sha1" => "sha1", "sha256" => "sha256" ); if (array_key_exists($algo, $supported_algos)) return $supported_algos[$algo]; throw new APIException("Algorithm '$algo' is not supported or has been disabled."); } /** * Calculate the HMAC for the query. * This function signs an api request using the information provided and is then verified by * searunner. * * @param $algo string The HMAC algorithm used as stored in X-Searunner-hmac-algo. * @param $time string String representation of unix time as stored in X-Searunner-time. * @param $api_key string Your api key. * @param $secret string Your secret key. * @param $get_variables string URLEncoded string representation of the get variable parameters, eg "format=php&method=searunner.test". * @param $post_hash string Optional sha1 hash of the post data. * @return string The HMAC string. */ function calculate_hmac($algo, $time, $api_key, $secret_key, $get_variables, $post_hash = "") { $ctx = hash_init(map_api_hash($algo), HASH_HMAC, $secret_key); hash_update($ctx, trim($time)); hash_update($ctx, trim($api_key)); hash_update($ctx, trim($get_variables)); if (trim($post_hash)!="") hash_update($ctx, trim($post_hash)); return hash_final($ctx); } /** * Calculate a hash for some post data. * * TODO: Work out how to handle really large bits of data. * * @param $postdata string The post data. * @param $algo string The algorithm used. * @return string The hash. */ function calculate_posthash($postdata, $algo) { $ctx = hash_init(map_api_hash($algo)); hash_update($ctx, $postdata); return hash_final($ctx); } /** * This function will do two things. Firstly it verifys that a $hmac hasn't been seen before, and * secondly it will add the given hmac to the cache. * * TODO : REWRITE TO NOT USE ZEND * * @param $hmac The hmac string. * @return bool True if replay detected, false if not. */ function cache_hmac_check_replay($hmac) { global $CONFIG; $cache_dir = $CONFIG->cache_path; if (!$cache_dir) throw new ConfigurationException("Cache directory 'cache_path' not set."); $cache = new ElggFileCache($cache_dir, 90000); // cache lifetime is 25 hours (see time window in get_and_validate_api_headers() ) if (!$result = $cache->load($hmac)) { $cache->save($hmac, $hmac); return false; } return true; } /** * Find an API User's details based on the provided public api key. * * @param int $site_guid The GUID of the site. * @param string $api_key The API Key * @return mixed stdClass representing the database row or false. */ function get_api_user($site_guid, $api_key) { global $CONFIG; $api_key = sanitise_string($api_key); $site_guid = (int)$site_guid; return get_data_row("SELECT * from {$CONFIG->dbprefix}api_users where api_key='$api_key' and site_guid=$site_guid and active=1"); } /** * This function looks at the super-global variable $_SERVER and extracts the various * header variables needed to pass to the validation functions after performing basic validation. * * @return stdClass Containing all the values. * @throws APIException Detailing any error. */ function get_and_validate_api_headers() { $result = new stdClass; $result->method = $_SERVER['REQUEST_METHOD']; if (($result->method != "GET") && ($result->method!= "POST")) // Only allow these methods throw new APIException("Request method must be GET or POST"); $result->api_key = $_SERVER['HTTP_X_ELGG_APIKEY']; if ($result->api_key == "") throw new APIException("Missing X-Elgg-apikey HTTP header"); $result->hmac = $_SERVER['HTTP_X_ELGG_HMAC']; if ($result->hmac == "") throw new APIException("Missing X-Elgg-hmac header"); $result->hmac_algo = $_SERVER['HTTP_X_ELGG_HMAC_ALGO']; if ($result->hmac_algo == "") throw new APIException("Missing X-Elgg-hmac-algo header"); $result->time = $_SERVER['HTTP_X_ELGG_TIME']; if ($result->time == "") throw new APIException("Missing X-Elgg-time header"); if (($result->time<(microtime(true)-86400.00)) || ($result->time>(microtime(true)+86400.00))) // Basic timecheck, think about making this smaller if we get loads of users and the cache gets really big. throw new APIException("X-Elgg-time is too far in the past or future"); $result->get_variables = $_SERVER['QUERY_STRING']; if ($result->get_variables == "") throw new APIException("No data on the query string"); if ($result->method=="POST") { $result->posthash = $_SERVER['HTTP_X_ELGG_POSTHASH']; if ($result->posthash == "") throw new APIException("Missing X-Elgg-posthash header"); $result->posthash_algo = $_SERVER['HTTP_X_ELGG_POSTHASH_ALGO']; if ($result->posthash_algo == "") throw new APIException("Missing X-Elgg-posthash_algo header"); $result->content_type = $_SERVER['CONTENT_TYPE']; if ($result->content_type == "") throw new APIException("Missing content type for post data"); } return $result; } /** * Return a sanitised form of the POST data sent to the script * * @return string */ function get_post_data() { global $GLOBALS; return $GLOBALS['HTTP_RAW_POST_DATA']; } // PAM functions ////////////////////////////////////////////////////////////////////////// $PAM_HANDLERS = array(); $PAM_HANDLER_MSG = array(); // Messages /** * Register a method of authenticating an incoming API request. * This function registers a PAM handler which is a function that matches the desciption pam_handler_name() * and returns either 'true' if an incoming api request was authorised, false or throws an exception if not. * * The handlers are tried in turn until one of them successfully authenticates the session. * * This architecture lets an administrator choose what methods to accept for API authentication or * * @param unknown_type $handler */ function register_api_pam_handler($handler) { global $PAM_HANDLERS; if (is_callable($handler)) { $PAM_HANDLERS[$handler] = $handler; return true; } return false; } /** * Magically authenticate an API session using one of the registered methods. * * This function will return true if authentication was possible, otherwise it'll throw an exception. * * If $CONFIG->debug is set then additional debug information will be returned. */ function api_pam_authenticate() { global $PAM_HANDLERS, $PAM_HANDLER_MSG; global $CONFIG; $dbg_msgs = array(); foreach ($PAM_HANDLERS as $k => $v) { try { // Execute the handler if ($v()) { // Explicitly returned true $PAM_HANDLER_MSG[$k] = "Authenticated!"; return true; } else $PAM_HANDLER_MSG[$k] = "Not Authenticated."; } catch (Exception $e) { $PAM_HANDLER_MSG[$k] = "$e"; } } // Got this far, so no methods could be found to authenticate the session throw new SecurityException("No authentication methods were found that could authenticate this request."); } /** * See if the user has a valid login sesson. */ function pam_auth_session() { return isloggedin(); } /** * Secure authentication through headers and HMAC. */ function pam_auth_hmac() { global $CONFIG; $api_header = get_and_validate_api_headers(); // Get api header $api_user = get_api_user($CONFIG->site_id, $api_header->api_key); // Pull API user details if ($api_user) { // Get the secret key $secret_key = $api_user->secret; // Validate HMAC $hmac = calculate_hmac($api_header->hmac_algo, $api_header->time, $api_header->api_key, $secret_key, $api_header->get_variables, $api_header->method == 'POST' ? $api_header->posthash : ""); if (strcmp( $api_header->hmac, $hmac )==0) { // Now make sure this is not a replay if (!cache_hmac_check_replay($hmac)) { // Validate post data if ($api_header->method=="POST") { $postdata = get_post_data(); $calculated_posthash = calculate_posthash($postdata, $api_header->posthash_algo); if (strcmp($api_header->posthash, $calculated_posthash)!=0) throw new SecurityException("POST data hash is invalid - Expected $calculated_posthash but got {$api_header->posthash}."); } // If we've passed all the checks so far then we can be reasonably certain that the request is authentic, so return this fact to the PAM engine. return true; } else throw new SecurityException("Packet signature already seen."); } else throw new SecurityException("HMAC is invalid. {$api_header->hmac} != [calc]$hmac = {$api_header->hmac_algo}(**SECRET KEY**, time:{$api_header->time}, apikey:{$api_header->api_key}, get_vars:{$api_header->get_variables}" . ($api_header->method=="POST"? "posthash:$api_header->posthash}" : ")")); } else throw new SecurityException("Invalid or missing API Key.",ErrorResult::$RESULT_FAIL_APIKEY_INVALID); return false; } // Output functions /////////////////////////////////////////////////////////////////////// $API_OUTPUT_FUNCTIONS = array(); /** * Register an API output handler. * This function is used by the system and the plugins to register an output encoding method for * returning API results. * * @param string $form The format string, eg 'xml' or 'php' * @param string $function The function, which must be in the format function_name(stdClass $result) and return a string. * @return bool */ function register_api_outputhandler($form, $function) { global $API_OUTPUT_FUNCTIONS; if ( ($form!="") && ($function!="")) { $API_OUTPUT_FUNCTIONS[$form] = $function; return true; } return false; } /** * Output the result, with the given fault. * * @param GenericResult $result Result object. * @param string $format The format * @return string */ function output_result(GenericResult $result, $format) { global $API_OUTPUT_FUNCTIONS; if ( (array_key_exists($format, $API_OUTPUT_FUNCTIONS)) && (is_callable($API_OUTPUT_FUNCTIONS[$format])) ) return $API_OUTPUT_FUNCTIONS[$format]($result->export()); // We got here, so no output format was found. Output an error $result = print_r($result->export(), true); return <<< END Something went wrong...

API Output Error

Something went badly wrong while outputting the result of your request in '$format' format. The result and any errors are displayed in raw text below.

$result
END; } function xml_result_handler(stdClass $result) { header("Content-Type: text/xml"); return serialise_object_to_xml($result, "elgg"); } function php_result_handler(stdClass $result) { return serialize($result); } function json_result_handler(stdClass $result) { return json_encode($result); } function csv_result_handler(stdClass $result) { throw new NotImplementedException("CSV View currently not implemented"); } // Register some format handlers register_api_outputhandler('xml', 'xml_result_handler'); register_api_outputhandler('php', 'php_result_handler'); register_api_outputhandler('json', 'json_result_handler'); register_api_outputhandler('csv', 'csv_result_handler'); // Error handler functions //////////////////////////////////////////////////////////////// /** Define a global array of errors */ $ERRORS = array(); /** * PHP Error handler function. * This function acts as a wrapper to catch and report PHP error messages. * * @see http://uk3.php.net/set-error-handler * @param unknown_type $errno * @param unknown_type $errmsg * @param unknown_type $filename * @param unknown_type $linenum * @param unknown_type $vars */ function __php_api_error_handler($errno, $errmsg, $filename, $linenum, $vars) { global $ERRORS; $error = date("Y-m-d H:i:s (T)") . ": \"" . $errmsg . "\" in file " . $filename . " (line " . $linenum . ")"; switch ($errno) { case E_USER_ERROR: error_log("ERROR: " . $error); $ERRORS[] = "ERROR: " .$error; // Since this is a fatal error, we want to stop any further execution but do so gracefully. throw new Exception("ERROR: " . $error); break; case E_WARNING : case E_USER_WARNING : error_log("WARNING: " . $error); $ERRORS[] = "WARNING: " .$error; break; default: error_log("DEBUG: " . $error); $ERRORS[] = "DEBUG: " .$error; } } /** * PHP Exception handler. * This is a generic exception handler for PHP exceptions. This will catch any * uncaught exception and return it as an ErrorResult in the requested format. * * @param Exception $exception */ function __php_api_exception_handler($exception) { error_log("*** FATAL EXCEPTION (API) *** : " . $exception); echo output_result( ErrorResult::getInstance( $exception->getMessage(), $exception->getCode() == 0 ? ErrorResult::$RESULT_FAIL : $exception->getCode(), $exception), get_input('format','php') // Attempt to get the requested format if passed. ); } ?>