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<?php
/**
* -----XML-Envelope---------------------------------
* | |
* | Encrypted-Symmetric-key---------------- |
* | |_____________________________________| |
* | |
* | Encrypted data------------------------- |
* | | | |
* | | -XML-Envelope------------------ | |
* | | | | | |
* | | | --Signature------------- | | |
* | | | |______________________| | | |
* | | | | | |
* | | | --Signed-Payload-------- | | |
* | | | | | | | |
* | | | | XML-RPC Request | | | |
* | | | |______________________| | | |
* | | | | | |
* | | |_____________________________| | |
* | |_____________________________________| |
* | |
* |________________________________________________|
*
*/
/* Strip encryption envelope (if present) and decrypt data
*
* @param string $HTTP_RAW_POST_DATA The XML that the client sent
*
* @throws mnet_server_exception
*
* @return string XML with any encryption envolope removed
*/
function mnet_server_strip_encryption($HTTP_RAW_POST_DATA) {
$remoteclient = get_mnet_remote_client();
$crypt_parser = new mnet_encxml_parser();
$crypt_parser->parse($HTTP_RAW_POST_DATA);
$mnet = get_mnet_environment();
if (!$crypt_parser->payload_encrypted) {
return $HTTP_RAW_POST_DATA;
}
// Make sure we know who we're talking to
$host_record_exists = $remoteclient->set_wwwroot($crypt_parser->remote_wwwroot);
if (false == $host_record_exists) {
throw new mnet_server_exception(7020, 'wrong-wwwroot', $crypt_parser->remote_wwwroot);
}
// This key is symmetric, and is itself encrypted. Can be decrypted using our private key
$key = array_pop($crypt_parser->cipher);
// This data is symmetrically encrypted, can be decrypted using the above key
$data = array_pop($crypt_parser->cipher);
$crypt_parser->free_resource();
$payload = ''; // Initialize payload var
// &$payload
$isOpen = openssl_open(base64_decode($data), $payload, base64_decode($key), $mnet->get_private_key());
if ($isOpen) {
$remoteclient->was_encrypted();
return $payload;
}
// Decryption failed... let's try our archived keys
$openssl_history = get_config('mnet', 'openssl_history');
if(empty($openssl_history)) {
$openssl_history = array();
set_config('openssl_history', serialize($openssl_history), 'mnet');
} else {
$openssl_history = unserialize($openssl_history);
}
foreach($openssl_history as $keyset) {
$keyresource = openssl_pkey_get_private($keyset['keypair_PEM']);
$isOpen = openssl_open(base64_decode($data), $payload, base64_decode($key), $keyresource);
if ($isOpen) {
// It's an older code, sir, but it checks out
$remoteclient->was_encrypted();
$remoteclient->encrypted_to($keyresource);
$remoteclient->set_pushkey();
return $payload;
}
}
//If after all that we still couldn't decrypt the message, error out.
throw new mnet_server_exception(7023, 'encryption-invalid');
}
/* Strip signature envelope (if present), try to verify any signature using our record of remote peer's public key.
*
* @param string $plaintextmessage XML envelope containing XMLRPC request and signature
*
* @return string XMLRPC request
*/
function mnet_server_strip_signature($plaintextmessage) {
$remoteclient = get_mnet_remote_client();
$sig_parser = new mnet_encxml_parser();
$sig_parser->parse($plaintextmessage);
if ($sig_parser->signature == '') {
return $plaintextmessage;
}
// Record that the request was signed in some way
$remoteclient->was_signed();
// Load any information we have about this mnet peer
$remoteclient->set_wwwroot($sig_parser->remote_wwwroot);
$payload = base64_decode($sig_parser->data_object);
$signature = base64_decode($sig_parser->signature);
$certificate = $remoteclient->public_key;
// If we don't have any certificate for the host, don't try to check the signature
// Just return the parsed request
if ($certificate == false) {
return $payload;
}
// Does the signature match the data and the public cert?
$signature_verified = openssl_verify($payload, $signature, $certificate);
if ($signature_verified == 0) {
// $signature was not generated for $payload using $certificate
// Get the key the remote peer is currently publishing:
$currkey = mnet_get_public_key($remoteclient->wwwroot, $remoteclient->application);
// If the key the remote peer is currently publishing is different to $certificate
if($currkey != $certificate) {
// if pushkey is already set, it means the request was encrypted to an old key
// in mnet_server_strip_encryption.
// if we call refresh_key() here before pushing out our new key,
// and the other site ALSO has a new key,
// we'll get into an infinite keyswap loop
// so push just bail here, and push out the new key.
// the next request will get through to refresh_key
if ($remoteclient->pushkey) {
return false;
}
// Try and get the server's new key through trusted means
$remoteclient->refresh_key();
// If we did manage to re-key, try to verify the signature again using the new public key.
$certificate = $remoteclient->public_key;
$signature_verified = openssl_verify($payload, $signature, $certificate);
}
}
if ($signature_verified == 1) {
$remoteclient->signature_verified();
$remoteclient->touch();
}
$sig_parser->free_resource();
return $payload;
}
/**
* Return the proper XML-RPC content to report an error in the local language.
*
* @param int $code The ID code of the error message
* @param string $text The full string of the error message (get_string will <b>not be called</b>)
* @param string $param The $a param for the error message in the lang file
* @return string $text The text of the error message
*/
function mnet_server_fault($code, $text, $param = null) {
if (!is_numeric($code)) {
$code = 0;
}
$code = intval($code);
return mnet_server_fault_xml($code, $text);
}
/**
* Return the proper XML-RPC content to report an error.
*
* @param int $code The ID code of the error message
* @param string $text The error message
* @param resource $privatekey The private key that should be used to sign the response
* @return string $text The XML text of the error message
*/
function mnet_server_fault_xml($code, $text, $privatekey = null) {
global $CFG;
// Replace illegal XML chars - is this already in a lib somewhere?
$text = str_replace(array('<','>','&','"',"'"), array('&lt;','&gt;','&amp;','&quot;','&apos;'), $text);
$return = mnet_server_prepare_response('<?xml version="1.0"?>
<methodResponse>
<fault>
<value>
<struct>
<member>
<name>faultCode</name>
<value><int>'.$code.'</int></value>
</member>
<member>
<name>faultString</name>
<value><string>'.$text.'</string></value>
</member>
</struct>
</value>
</fault>
</methodResponse>', $privatekey);
if ($code != 7025) { // new key responses
mnet_debug("XMLRPC Error Response $code: $text");
//mnet_debug($return);
}
return $return;
}
/**
* Package a response in any required envelope, and return it to the client
*
* @param string $response The XMLRPC response string
* @param resource $privatekey The private key to sign the response with
* @return string The encoded response string
*/
function mnet_server_prepare_response($response, $privatekey = null) {
$remoteclient = get_mnet_remote_client();
if ($remoteclient->request_was_signed) {
$response = mnet_sign_message($response, $privatekey);
}
if ($remoteclient->request_was_encrypted) {
$response = mnet_encrypt_message($response, $remoteclient->public_key);
}
return $response;
}
/**
* If security checks are passed, dispatch the request to the function/method
*
* The config variable 'mnet_dispatcher_mode' can be:
* strict: Only execute functions that are in specific files
* off: The default - don't execute anything
*
* @param string $payload The XML-RPC request
*
* @throws mnet_server_exception
*
* @return No return val - just echo the response
*/
function mnet_server_dispatch($payload) {
global $CFG, $DB;
$remoteclient = get_mnet_remote_client();
// xmlrpc_decode_request returns an array of parameters, and the $method
// variable (which is passed by reference) is instantiated with the value from
// the methodName tag in the xml payload
// xmlrpc_decode_request($xml, &$method)
$params = xmlrpc_decode_request($payload, $method);
// $method is something like: "mod/forum/lib.php/forum_add_instance"
// $params is an array of parameters. A parameter might itself be an array.
// Whitelist characters that are permitted in a method name
// The method name must not begin with a / - avoid absolute paths
// A dot character . is only allowed in the filename, i.e. something.php
if (0 == preg_match("@^[A-Za-z0-9]+/[A-Za-z0-9/_\.-]+(\.php/)?[A-Za-z0-9_-]+$@",$method)) {
throw new mnet_server_exception(713, 'nosuchfunction');
}
if(preg_match("/^system\./", $method)) {
$callstack = explode('.', $method);
} else {
$callstack = explode('/', $method);
// callstack will look like array('mod', 'forum', 'lib.php', 'forum_add_instance');
}
/**
* What has the site administrator chosen as his dispatcher setting?
* strict: Only execute functions that are in specific files
* off: The default - don't execute anything
*/
////////////////////////////////////// OFF
if (!isset($CFG->mnet_dispatcher_mode) ) {
set_config('mnet_dispatcher_mode', 'off');
throw new mnet_server_exception(704, 'nosuchservice');
} elseif ('off' == $CFG->mnet_dispatcher_mode) {
throw new mnet_server_exception(704, 'nosuchservice');
////////////////////////////////////// SYSTEM METHODS
} elseif ($callstack[0] == 'system') {
$functionname = $callstack[1];
$xmlrpcserver = xmlrpc_server_create();
// register all the system methods
$systemmethods = array('listMethods', 'methodSignature', 'methodHelp', 'listServices', 'listFiles', 'retrieveFile', 'keyswap');
foreach ($systemmethods as $m) {
// I'm adding the canonical xmlrpc references here, however we've
// already forbidden that the period (.) should be allowed in the call
// stack, so if someone tries to access our XMLRPC in the normal way,
// they'll already have received a RPC server fault message.
// Maybe we should allow an easement so that regular XMLRPC clients can
// call our system methods, and find out what we have to offer?
$handler = 'mnet_system';
if ($m == 'keyswap') {
$handler = 'mnet_keyswap';
}
if ($method == 'system.' . $m || $method == 'system/' . $m) {
xmlrpc_server_register_method($xmlrpcserver, $method, $handler);
$response = xmlrpc_server_call_method($xmlrpcserver, $payload, $remoteclient, array("encoding" => "utf-8"));
$response = mnet_server_prepare_response($response);
echo $response;
xmlrpc_server_destroy($xmlrpcserver);
return;
}
}
throw new mnet_server_exception(7018, 'nosuchfunction');
//////////////////////////////////// NORMAL PLUGIN DISPATCHER
} else {
// anything else comes from some sort of plugin
if ($rpcrecord = $DB->get_record('mnet_rpc', array('xmlrpcpath' => $method))) {
$response = mnet_server_invoke_plugin_method($method, $callstack, $rpcrecord, $payload);
$response = mnet_server_prepare_response($response);
echo $response;
return;
// if the rpc record isn't found, check to see if dangerous mode is on
////////////////////////////////////// DANGEROUS
} else if ('dangerous' == $CFG->mnet_dispatcher_mode && $remoteclient->plaintext_is_ok()) {
$functionname = array_pop($callstack);
$filename = clean_param(implode('/',$callstack), PARAM_PATH);
if (0 == preg_match("/php$/", $filename)) {
// Filename doesn't end in 'php'; possible attack?
// Generate error response - unable to locate function
throw new mnet_server_exception(7012, 'nosuchfunction');
}
// The call stack holds the path to any include file
$includefile = $CFG->dirroot.'/'.$filename;
$response = mnet_server_invoke_dangerous_method($includefile, $functionname, $method, $payload);
echo $response;
return;
}
}
throw new mnet_server_exception(7012, 'nosuchfunction');
}
/**
* Execute the system functions - mostly for introspection
*
* @param string $method XMLRPC method name, e.g. system.listMethods
* @param array $params Array of parameters from the XMLRPC request
* @param string $hostinfo Hostinfo object from the mnet_host table
*
* @throws mnet_server_exception
*
* @return mixed Response data - any kind of PHP variable
*/
function mnet_system($method, $params, $hostinfo) {
global $CFG, $DB;
if (empty($hostinfo)) return array();
$id_list = $hostinfo->id;
if (!empty($CFG->mnet_all_hosts_id)) {
$id_list .= ', '.$CFG->mnet_all_hosts_id;
}
if ('system.listMethods' == $method || 'system/listMethods' == $method) {
$query = '
SELECT DISTINCT
rpc.functionname,
rpc.xmlrpcpath
FROM
{mnet_host2service} h2s
JOIN {mnet_service2rpc} s2r ON h2s.serviceid = s2r.serviceid
JOIN {mnet_rpc} rpc ON s2r.rpcid = rpc.id
JOIN {mnet_service} svc ON svc.id = s2r.serviceid
WHERE
h2s.hostid in ('.$id_list .') AND
h2s.publish = 1 AND rpc.enabled = 1
' . ((count($params) > 0) ? 'AND svc.name = ? ' : '') . '
ORDER BY
rpc.xmlrpcpath ASC';
if (count($params) > 0) {
$params = array($params[0]);
}
$methods = array();
foreach ($DB->get_records_sql($query, $params) as $result) {
$methods[] = $result->xmlrpcpath;
}
return $methods;
} elseif (in_array($method, array('system.methodSignature', 'system/methodSignature', 'system.methodHelp', 'system/methodHelp'))) {
$query = '
SELECT DISTINCT
rpc.functionname,
rpc.help,
rpc.profile
FROM
{mnet_host2service} h2s,
{mnet_service2rpc} s2r,
{mnet_rpc} rpc
WHERE
rpc.xmlrpcpath = ? AND
s2r.rpcid = rpc.id AND
h2s.publish = 1 AND rpc.enabled = 1 AND
h2s.serviceid = s2r.serviceid AND
h2s.hostid in ('.$id_list .')';
$params = array($params[0]);
if (!$result = $DB->get_record_sql($query, $params)) {
return false;
}
if (strpos($method, 'methodSignature') !== false) {
return unserialize($result->profile);
}
return $result->help;
} elseif ('system.listServices' == $method || 'system/listServices' == $method) {
$query = '
SELECT DISTINCT
s.id,
s.name,
s.apiversion,
h2s.publish,
h2s.subscribe
FROM
{mnet_host2service} h2s,
{mnet_service} s
WHERE
h2s.serviceid = s.id AND
(h2s.publish = 1 OR h2s.subscribe = 1) AND
h2s.hostid in ('.$id_list .')
ORDER BY
s.name ASC';
$params = array();
$result = $DB->get_records_sql($query, $params);
$services = array();
if (is_array($result)) {
foreach($result as $service) {
$services[] = array('name' => $service->name,
'apiversion' => $service->apiversion,
'publish' => $service->publish,
'subscribe' => $service->subscribe);
}
}
return $services;
}
throw new mnet_server_exception(7019, 'nosuchfunction');
}
/**
* Invoke a normal style plugin method
* This will verify permissions first.
*
* @param string $method the full xmlrpc method that was called eg auth/mnet/auth.php/user_authorise
* @param array $callstack the exploded callstack
* @param stdclass $rpcrecord the record from mnet_rpc
*
* @return mixed the response from the invoked method
*/
function mnet_server_invoke_plugin_method($method, $callstack, $rpcrecord, $payload) {
mnet_verify_permissions($rpcrecord); // will throw exceptions
mnet_setup_dummy_method($method, $callstack, $rpcrecord);
$methodname = array_pop($callstack);
$xmlrpcserver = xmlrpc_server_create();
xmlrpc_server_register_method($xmlrpcserver, $method, 'mnet_server_dummy_method');
$response = xmlrpc_server_call_method($xmlrpcserver, $payload, $methodname, array("encoding" => "utf-8"));
xmlrpc_server_destroy($xmlrpcserver);
return $response;
}
/**
* Initialize the object (if necessary), execute the method or function, and
* return the response
*
* @param string $includefile The file that contains the object definition
* @param string $methodname The name of the method to execute
* @param string $method The full path to the method
* @param string $payload The XML-RPC request payload
* @param string $class The name of the class to instantiate (or false)
*
* @throws mnet_server_exception
*
* @return string The XML-RPC response
*/
function mnet_server_invoke_dangerous_method($includefile, $methodname, $method, $payload) {
if (file_exists($CFG->dirroot . $includefile)) {
require_once $CFG->dirroot . $includefile;
// $callprefix matches the rpc convention
// of not having a leading slash
$callprefix = preg_replace('!^/!', '', $includefile);
} else {
throw new mnet_server_exception(705, "nosuchfile");
}
if ($functionname != clean_param($functionname, PARAM_PATH)) {
throw new mnet_server_exception(7012, "nosuchfunction");
}
if (!function_exists($functionname)) {
throw new mnet_server_exception(7012, "nosuchfunction");
}
$xmlrpcserver = xmlrpc_server_create();
xmlrpc_server_register_method($xmlrpcserver, $method, 'mnet_server_dummy_method');
$response = xmlrpc_server_call_method($xmlrpcserver, $payload, $methodname, array("encoding" => "utf-8"));
xmlrpc_server_destroy($xmlrpcserver);
return $response;
}
/**
* Accepts a public key from a new remote host and returns the public key for
* this host. If 'register all hosts' is turned on, it will bootstrap a record
* for the remote host in the mnet_host table (if it's not already there)
*
* @param string $function XML-RPC requires this but we don't... discard!
* @param array $params Array of parameters
* $params[0] is the remote wwwroot
* $params[1] is the remote public key
* @return string The XML-RPC response
*/
function mnet_keyswap($function, $params) {
global $CFG;
$return = array();
$mnet = get_mnet_environment();
if (!empty($CFG->mnet_register_allhosts)) {
$mnet_peer = new mnet_peer();
@list($wwwroot, $pubkey, $application) = each($params);
$keyok = $mnet_peer->bootstrap($wwwroot, $pubkey, $application);
if ($keyok) {
$mnet_peer->commit();
}
}
return $mnet->public_key;
}
/**
* Verify that the requested xmlrpc method can be called
* This just checks the method exists in the rpc table and is enabled.
*
* @param stdclass $rpcrecord the record from mnet_rpc
*
* @throws mnet_server_exception
*/
function mnet_verify_permissions($rpcrecord) {
global $CFG, $DB;
$remoteclient = get_mnet_remote_client();
$id_list = $remoteclient->id;
if (!empty($CFG->mnet_all_hosts_id)) {
$id_list .= ', '.$CFG->mnet_all_hosts_id;
}
$sql = "SELECT
r.*, h2s.publish
FROM
{mnet_rpc} r
JOIN {mnet_service2rpc} s2r ON s2r.rpcid = r.id
LEFT JOIN {mnet_host2service} h2s ON h2s.serviceid = s2r.serviceid
WHERE
r.id = ? AND
h2s.hostid in ($id_list)";
$params = array($rpcrecord->id);
if (!$permission = $DB->get_record_sql($sql, $params)) {
throw new mnet_server_exception(7012, "nosuchfunction");
} else if (!$permission->publish || !$permission->enabled) {
throw new mnet_server_exception(707, "nosuchfunction");
}
}
/**
* Figure out exactly what needs to be called and stashes it in $remoteclient
* Does some further verification that the method is callable
*
* @param string $method the full xmlrpc method that was called eg auth/mnet/auth.php/user_authorise
* @param array $callstack the exploded callstack
* @param stdclass $rpcrecord the record from mnet_rpc
*
* @throws mnet_server_exception
*/
function mnet_setup_dummy_method($method, $callstack, $rpcrecord) {
global $CFG;
$remoteclient = get_mnet_remote_client();
// verify that the callpath in the stack matches our records
// callstack will look like array('mod', 'forum', 'lib.php', 'forum_add_instance');
$path = get_plugin_directory($rpcrecord->plugintype, $rpcrecord->pluginname);
$path = substr($path, strlen($CFG->dirroot)+1); // this is a bit hacky and fragile, it is not guaranteed that plugins are in dirroot
array_pop($callstack);
$providedpath = implode('/', $callstack);
if ($providedpath != $path . '/' . $rpcrecord->filename) {
throw new mnet_server_exception(705, "nosuchfile");
}
if (!file_exists($CFG->dirroot . '/' . $providedpath)) {
throw new mnet_server_exception(705, "nosuchfile");
}
require_once($CFG->dirroot . '/' . $providedpath);
if (!empty($rpcrecord->classname)) {
if (!class_exists($rpcrecord->classname)) {
throw new mnet_server_exception(708, 'nosuchclass');
}
if (!$rpcrecord->static) {
try {
$object = new $rpcrecord->classname;
} catch (Exception $e) {
throw new mnet_server_exception(709, "classerror");
}
if (!is_callable(array($object, $rpcrecord->functionname))) {
throw new mnet_server_exception(706, "nosuchfunction");
}
$remoteclient->object_to_call($object);
} else {
if (!is_callable(array($rpcrecord->classname, $rpcrecord->functionname))) {
throw new mnet_server_exception(706, "nosuchfunction");
}
$remoteclient->static_location($rpcrecord->classname);
}
}
}
/**
* Dummy function for the XML-RPC dispatcher - use to call a method on an object
* or to call a function
*
* Translate XML-RPC's strange function call syntax into a more straightforward
* PHP-friendly alternative. This dummy function will be called by the
* dispatcher, and can be used to call a method on an object, or just a function
*
* The methodName argument (eg. mnet/testlib/mnet_concatenate_strings)
* is ignored.
*
* @throws mnet_server_exception
*
* @param string $methodname We discard this - see 'functionname'
* @param array $argsarray Each element is an argument to the real
* function
* @param string $functionname The name of the PHP function you want to call
* @return mixed The return value will be that of the real
* function, whatever it may be.
*/
function mnet_server_dummy_method($methodname, $argsarray, $functionname) {
$remoteclient = get_mnet_remote_client();
try {
if (is_object($remoteclient->object_to_call)) {
return @call_user_func_array(array($remoteclient->object_to_call,$functionname), $argsarray);
} else if (!empty($remoteclient->static_location)) {
return @call_user_func_array(array($remoteclient->static_location, $functionname), $argsarray);
} else {
return @call_user_func_array($functionname, $argsarray);
}
} catch (Exception $e) {
exit(mnet_server_fault($e->getCode(), $e->getMessage()));
}
}
/**
* mnet server exception. extends moodle_exception, but takes slightly different arguments.
* and unlike the rest of moodle, the actual int error code is used.
* this exception should only be used during an xmlrpc server request, ie, not for client requests.
*/
class mnet_server_exception extends moodle_exception {
/**
* @param int $intcode the numerical error associated with this fault. this is <b>not</b> the string errorcode
* @param string $langkey the error message in full (<b>get_string will not be used</b>)
* @param string $module the language module, defaults to 'mnet'
* @param mixed $a params for get_string
*/
public function __construct($intcode, $languagekey, $module='mnet', $a=null) {
parent::__construct($languagekey, $module, '', $a);
$this->code = $intcode;
}
}
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