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|
/* CodeQ: an online programming tutor.
Copyright (C) 2015 UL FRI
This program is free software: you can redistribute it and/or modify it under
the terms of the GNU Affero General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option) any
later version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
var engine = require('engine.io'), // web sockets communication handler, sitting on the low-level HTTP handler
http = require('http'), // HTTP library
https = require('https'), // HTTPS library
http_server = http.createServer(), // the low-level HTTP handler
querystring = require('querystring'), // encodes and decodes URL query strings
net = require('net'), // TCP sockets library
Promise = require('bluebird'), // the promises library
log4js = require('log4js'), // the logger
url = require('url'), // URL parser
express = require('express'), // library providing the Express web framework
http_app = express(), // web framework engine, sitting on the low-level HTTP handler
bodyParser = require('body-parser');
var SAML_SERVICE_URL = process.env.CODEQ_SAML_SERVICE_URL || 'https://codeq.si/saml/';
var samlUrlParsed = url.parse(SAML_SERVICE_URL),
samlIsHttps = samlUrlParsed.protocol === 'https:';
// ================================================================================
// The logger
// ================================================================================
log4js.loadAppender('file');
log4js.addAppender(log4js.appenders.file(process.env.CODEQ_WEB_LOG || 'codeq-web.log'), 'log');
var logger = log4js.getLogger('log');
var logException = function (msg, error) {
if ((error instanceof Error) && (typeof error.stack === 'string')) msg += '\n' + error.stack;
logger.error(msg);
};
// prevent the node from exiting because of an unhandled exception
Promise.onPossiblyUnhandledRejection(function (error) {
logException('Unhandled promise rejection: ' + error, error);
});
process.on('uncaughtException', function (error) {
logException('Uncaught exception: ' + error, error);
});
// ================================================================================
// Low-level HTTP handlers, just do the minimum and forward to upper layers
// ================================================================================
// instantiate the web socket communication handler
var server = new engine.Server({
'pingTimeout': 60000, // in ms
'pingInterval': 25000, // in ms
'maxHttpBufferSize': 100000, // in bytes, for polling
'transports': ['polling', 'websocket'],
'cookie': false // no cookies
});
http_server.listen(8083, 'localhost');
http_server.on('request', function (request, response) {
var uriParts = request.url.split('/'), // uriParts[0] will be an empty string, because uri must start with a /
params;
logger.debug('HTTP server request, URL: ' + request.url);
if ((uriParts.length >= 3) && (uriParts[1] === 'ws')) {
// could be a web services request, check if there's a path following
params = uriParts[2];
if (!params || (params[0] === '?')) {
server.handleRequest(request, response); // no path follows /ws/, only query string, forward it to engine.io
}
else {
http_app(request, response); // there's a path present beyond /ws/, forward it to express
}
}
else {
http_app(request, response); // URI does not begin with /ws/, forward it to express
}
});
http_server.on('upgrade', function (request, socket, head) {
server.handleUpgrade(request, socket, head); // initiating web socket communication
});
// ================================================================================
// Misc
// ================================================================================
var doubleDigit = function (d) {
var s = '' + d;
if (s.length < 2) return '0' + s;
return s;
};
var tripleDigit = function (d) {
var s = '' + d;
while (s.length < 3) s = '0' + s;
return s;
};
var formatTimestamp = function (t) {
var d = new Date(t);
return '' + d.getFullYear() + '-' + doubleDigit(d.getMonth()+1) + '-' + doubleDigit(d.getDate()) + ' ' +
doubleDigit(d.getHours()) + ':' + doubleDigit(d.getMinutes()) + ':' + doubleDigit(d.getSeconds()) + '.' + tripleDigit(d.getMilliseconds());
};
// ================================================================================
// Express web framework, handle any AJAX here
// ================================================================================
http_app.use(bodyParser.json());
http_app.get('/ws/logout', function (req, res) {
var sid = req.query.sid,
session = sessions[sid];
if (session) {
logger.debug('Logging out via AJAX, sid=' + sid);
guiHandlers.destroy(session, {'sid': sid, 'action': 'destroy'});
}
else if (sid) {
logger.warn('Cannot logout via AJAX: no session exists with sid=' + sid);
}
else {
logger.warn('No sid provided for AJAX logout');
}
res.set('Content-Type', 'text/plain');
res.send('OK');
});
http_app.post('/ws/clientlog', function (req, res) {
var b = req.body,
logs, i, l, line, output, f;
if (!b) {
logger.error('Empty clientlog request.');
return;
}
logs = b.logs;
if (!logs) {
logger.error('Empty logs in a clientlogs request.');
return;
}
output = ['Client logs from ', req.ip];
f = req.headers['x-forwarded-for'];
if (f) output.push(', forwarded for ', f);
output.push(':');
for (i = 0; i < logs.length; i++) {
l = logs[i];
output.push('\n [', formatTimestamp(l.t), '] [', l.l, '] ', l.m);
}
logger.info(output.join(''));
res.set('Content-Type', 'text/plain');
res.send('OK');
});
var performSamlAction = function (samlAction, params) {
return new Promise(function (resolve, reject) {
var aborted = false,
options = {
hostname: samlUrlParsed.hostname,
port: samlUrlParsed.port || (samlIsHttps ? 443 : 80),
path: samlUrlParsed.pathname + samlAction + '?' + querystring.encode(params),
method: 'GET',
rejectUnauthorized: false // allow server certificates we don't know
},
handleResponse = function (res) {
var chunks = [],
headers, m, s;
res.on('data', function (d) {
chunks.push(d);
});
res.on('end', function () {
if (aborted) return; // already handled
if (res.statusCode !== 200) {
// log error with all headers
headers = res.rawHeaders;
if (headers instanceof Array) m = headers.join('\n') + '\n\n' + chunks.join('');
else m = chunks.join('');
s = 'Received an error from the identity server: ' + res.statusCode + ' ' + res.statusMessage;
logger.error(s + '\n' + m);
reject(new Error(s));
return;
}
try {
m = JSON.parse(chunks.join(''));
}
catch (e) {
logException('Response from the identity server is not a JSON: ' + e + '\n' + chunks.join(''), e);
reject(e);
return;
}
resolve(m);
});
},
req;
if (samlIsHttps) req = https.request(options, handleResponse);
else req = http.request(options, handleResponse);
req.on('error', function (e) {
if (aborted) return; // already handled
logException('Error when trying to contact the identity server: ' + e, e);
reject(e instanceof Error ? e : new Error('' + e));
});
req.setTimeout(600000, function () { // 10 minutes timeout
var m = 'Timeout waiting for a reply from the identity server';
aborted = true;
req.abort();
logger.error(m);
reject(new Error(m));
});
req.end();
});
};
// ================================================================================
// Web services stuff - handlers for GUI requests, usually just forwarded to Python
// ================================================================================
// connected clients
var sessions = {
// sid: sessions description {sid: string, lastActivity: Date.now(), socket: net.Socket}
};
// GUI action handlers, keyed by the action name, values are functions that take the session and the message, or truthy values
var guiHandlers = {
// special-case action handlers
'destroy': function actionLogout(session, message) {
// logout and destroy the session, the user quit the app
logger.debug('Destroy GUI');
sendDataToPython(message).finally(function () {
//session.end({'type': 'reset', 'code': 9999, 'message': 'Bye.'});
session.end({'code': 0, 'message': 'Bye.', 'tid': message.tid, 'sid':message.sid});
}).done();
},
'saml_login': function samlLogin(session, message) {
var samlData = session.samlData,
p;
if (samlData && ('upgrade_account' in message)) {
message.saml_data = samlData.userData;
p = sendDataToPython(message);
}
else {
p = performSamlAction('WaitLogin', {'sid': session.sid})
.then(function (jsonObj) {
if (jsonObj.code !== 0) return jsonObj;
samlData = jsonObj.data;
if (!samlData) return {'tid': message.tid, 'sid': message.sid, 'code': -2, 'message': 'IdP proxy did not return any SAML data'};
if (!samlData.userData) return {'tid': message.tid, 'sid': message.sid, 'code': -3, 'message': 'IdP proxy did not return any SAML user data'};
// we need the SAML data to be able to perform global logout (saml_logout action)
session.samlData = samlData;
// add the data from SAML authentication, and forward everything to Python
message.saml_data = samlData.userData;
return sendDataToPython(message);
});
}
p.then(session.send)
.catch(function (e) {
var m = 'Error while trying to process the SAML request using the identity server: ' + e;
logException(m, e);
session.send({'tid': message.tid, 'sid': message.sid, 'code': -1, 'message': m});
})
.done();
},
'saml_logout': function samlLogout(session, message) {
var samlData = session.samlData,
keys, sd, key, i;
if (!samlData) {
session.send({'tid': message.tid, 'sid': message.sid, 'code': -1, 'message': 'The session was not authenticated using SAML'});
return;
}
// make a copy of SAML data, excluding user data
keys = Object.keys(samlData);
sd = {};
for (i = keys.length - 1; i >= 0; i--) {
key = keys[i];
if (key !== 'userData') sd[key] = samlData[key];
}
delete session.samlData;
performSamlAction('WaitLogout', {'sid': session.sid, 'saml': JSON.stringify(sd)})
.then(function (jsonObj) {
if (jsonObj.code !== 0) return jsonObj;
return sendDataToPython(message);
})
.then(session.send)
.catch(function (e) {
var m = 'Error while trying to process the SAML request using the identity server: ' + e;
logException(m, e);
session.send({'tid': message.tid, 'sid': message.sid, 'code': -2, 'message': m});
})
.done();
},
// actions to use default handling should define truthy values that are not functions
// (this is to filter out unnecessary traffic before it hits Python)
'login': true,
'logout': true,
'signup': true,
'change_password': true,
'activity': true,
'query': true,
'python_exec': true,
'python_push': true,
'python_stop': true,
'hint': true,
'test': true,
'get_attempts': true,
'get_solutions': true,
'get_current_solution': true,
'update_settings': true,
'load_problem': true,
'end_problem': true,
'user_stat': true,
'system': true
};
var system_handlers = {
'create_session': function (session, message) {
sendDataToPython({'action': 'create_session'})
.then(function (response) {
var sid, existingSession;
if (response.code !== 0) {
logger.debug('Python rejected create_session request from GUI');
session.send({'type': 'reset', 'message': response.message});
}
else {
logger.debug('Python accepted create_session request from GUI');
session.sid = sid = response.sid;
existingSession = sessions[sid];
sessions[sid] = session;
if (existingSession && (existingSession !== session)) {
existingSession.end({'type': 'reset', 'message': 'Supplanted with a new connection for the same session', 'sid': sid});
}
session.send({'type': 'sid', 'sid': sid});
}
})
.catch(function (error) {
session.send({'type': 'reset', 'message': 'Could not create a new session: ' + (error || 'unknown error')});
})
.done();
},
'connect_session': function (session, message) {
sendDataToPython({'action': 'login', 'sid': session.sid, 'username': message.username, 'password': message.password})
.then(function (response) {
var sid, existingSession;
if (response.code !== 0) {
logger.debug('Python rejected connect_session request from GUI');
session.send({'type': 'reset', 'message': response.message});
}
else {
logger.debug('Python accepted connect_session request from GUI');
session.sid = sid = response.sid;
existingSession = sessions[sid];
sessions[sid] = session;
if (existingSession && (existingSession !== session)) {
existingSession.end({'type': 'reset', 'message': 'Supplanted with a new connection for the same session', 'sid': sid});
}
session.send({'type': 'sid', 'sid': sid});
}
})
.catch(function (error) {
session.send({'type': 'reset', 'message': 'Could not connect the existing session: ' + (error || 'unknown error')});
})
.done();
}
};
server.on('connection', function (socket) {
var session,
fatal = function (jsonObj) {
// we need to preserve the socket object in a variable, so we can invoke close() on it later
var s = socket, m;
if (s === null) return;
if (jsonObj instanceof Error) jsonObj = {'code': -50, 'message': jsonObj.toString()};
m = JSON.stringify(jsonObj);
logger.debug('Sending to GUI from fatal(): ' + m);
try {
s.send(m, function () {
s.close();
s = null;
});
setTimeout(function () { // give it a second, then close it forcefully if it's still open
if (s) {
try {
s.close();
}
catch (e) {} // ignore
s = null;
}
}, 1000);
}
catch (e) {
logException('Failed to send reply to GUI about a fatal error: ' + e, e);
try {
s.close();
s = null;
}
catch (e) {} // ignore
}
socket = null; // this socket will no longer be processed
session.socket = null;
},
reply = function (jsonObj) {
var m;
if (!socket) return false;
m = JSON.stringify(jsonObj);
logger.debug('Sending to GUI from reply(): ' + m);
try {
socket.send(m);
return true;
}
catch (e) {
socket = null; // this socket will no longer be processed
session.socket = null;
return false;
}
};
logger.debug('A new client connection established');
session = {
'sid': null, // session id, null means the python hasn't authenticated us yet
'lastActivity': Date.now(),
'socket': socket,
'lastTID': -1, // last transaction ID, anything less than this we've already handled
'send': reply,
'end': fatal
};
socket.on('close', function (reason, description) { // description is optional
logger.debug('GUI socket closed: ' + reason);
if (session.sid !== null) {
if (sessions[session.sid] === session) delete sessions[session.sid];
sendDataToPython({'type': 'unregister', 'sid': session.sid}).done();
}
});
socket.on('message', function (data) {
var m, tid, action, handler;
if (socket === null) {
// this socket is not being processed anymore
logger.debug('Received something from GUI, but the socket is not being processed anymore');
return;
}
if (typeof data !== 'string') {
logger.debug('Received from GUI a binary message');
fatal({"code": -1, "message": "Can handle only text messages."});
return;
}
logger.debug('Received from GUI: ' + data);
try {
m = JSON.parse(data);
}
catch (e) {
fatal({"code": -2, "message": "Not a JSON message."});
return;
}
if (typeof m.type === 'string') {
// a system (meta) protocol message
handler = system_handlers[m.type];
if (!handler) logger.error('Received an unknown system message from client: ' + m.type);
else handler(session, m);
return;
}
tid = m['tid']; // transaction ID
if (typeof tid !== 'number') {
fatal({"code": -3, "message": "Transaction ID is missing or is not an integer."});
return;
}
if (Math.floor(tid) !== tid) {
fatal({"code": -4, "message": "Transaction ID is not an integer."});
return;
}
session.lastActivity = Date.now();
if (tid <= session.lastTID) {
// we already met this message, ignore it
return;
}
action = m['action'];
if (typeof action !== 'string') {
if (typeof action === 'undefined') {
reply({"code": -10, "tid": tid, "message": "Action is not set."});
}
else if (action === null) {
reply({"code": -11, "tid": tid, "message": "Action is null."});
}
else {
reply({"code": -12, "tid": tid, "message": "Action is not a string."});
}
return;
}
if (!action) {
reply({"code": -13, "tid": tid, "message": "Action is an empty string."});
return;
}
handler = guiHandlers[action];
if (!handler) {
reply({"code": -14, "tid": tid, "message": "Action is not understood."});
return;
}
try {
if (typeof handler === 'function') {
// special case processing
handler(session, m);
}
else {
// default processing: just proxy it through to Python
// logger.debug((session.sid || '[no session]') + ': Received ' + action + ' from GUI');
sendDataToPython(m).then(session.send, session.end).done();
}
session.lastTID = tid;
}
catch (e) {
reply({"code": -20, "tid": tid, "message": "Processing failed: " + e.toString()});
}
});
});
// ================================================================================
// Python server connection - sending to and receiving data from Python
// ================================================================================
var pythonClient = null, // the Socket for communication with the python server
pythonSaturated = false, // whether the kernel-level buffer is full, in this case only push into the pythonQueue
pythonQueue = [], // queue of packets, waiting to be sent
pythonPromises = {}; // promises waiting to be resolved with incoming data from python; key is TID, or TID:SID if SID is available, value is {'created': Date.now(), resolve: function, reject: function}
var pythonPromisesTimeout = setInterval(function () {
var floor = Date.now() - 300000, // timeout whatever is waiting for more than 5 minutes
key, resolver;
for (key in pythonPromises) {
if (pythonPromises.hasOwnProperty(key)) {
resolver = pythonPromises[key];
if ((typeof resolver === 'object') && (resolver !== null) && (resolver.created < floor)) {
delete pythonPromises[key];
resolver.reject(new Error('Timeout waiting for reply from server'));
logger.warn('Python promise timed out at key ' + key);
}
}
}
}, 60000); // once every minute
var processPacketFromPython = function processPacketFromPythonFunc(packetString) {
var m, session, isDummy,
key = null,
resolver = null;
logger.debug('Received from Python: ' + packetString);
try {
m = JSON.parse(packetString);
}
catch (e) {
logger.error('Failed to parse JSON data from Python: ' + e.toString() + '\n * The packet that caused the error: ' + packetString);
return;
}
if (typeof m.type === 'string') {
// system (meta) protocol message
switch (m.type) {
case 'session_expire':
if (typeof m.sid === 'string') {
session = sessions[m.sid];
if (session) session.end({'type': 'reset', 'message': 'Session expired'}); // send a system message to force the client to reset
else logger.warn('Received the session_expire system message from Python for a sid not handled by me: ' + m.sid);
}
else {
logger.error('Received the session_expire system message from Python, but no sid was included');
}
break;
default:
logger.warn('An unknown system message from Python: ' + m.type);
break;
}
return;
}
if ((typeof m.tid !== 'undefined') && (m.tid !== null)) {
if ((typeof m.tid === 'string') && (m.tid.charAt(0) === 'i')) {
// internal TID: only one way to key this one
key = m.tid;
resolver = pythonPromises[key];
}
else if (m.sid) {
key = m.tid + ':' + m.sid;
resolver = pythonPromises[key];
if (!resolver) {
key = '' + m.tid;
resolver = pythonPromises[key];
}
}
else {
key = '' + m.tid;
resolver = pythonPromises[key];
}
if (resolver) delete pythonPromises[key];
}
if (!m.tid || !resolver) {
// no promise is waiting, because this is a generated message, not a response to a previously sent message
isDummy = true;
for (key in m) {
if (m.hasOwnProperty(key) && (key !== 'tid') && (key != 'sid')) {
isDummy = false;
break;
}
}
if (isDummy) {
logger.debug('Message from Python is a dummy message, ignoring');
return;
}
if (!m.sid) {
// no session ID -> nowhere to send the message
logger.error('Message from Python dropped because there is no outstanding promise for it, and no session ID has been set');
return;
}
session = sessions[m.sid];
if (session) {
logger.debug('Proxying a message from Python directly to GUI, as there is no outstanding promise for it (probably a generated message)');
session.send(m);
}
else {
logger.error('Message from Python dropped because there is no outstanding promise for it, and no active session with ID ' + m.sid);
}
return;
}
logger.debug('Invoking the promise that is waiting for this Python message');
resolver.resolve(m);
};
// this is internal function to python connection handler
var sendPacketToPython = function sendPacketToPythonFunc(packet) {
if (pythonSaturated || (pythonClient === null)) return false;
logger.debug('Sending to Python: ' + packet);
try {
pythonSaturated = !pythonClient.write(packet);
return true;
}
catch (e) {
// an error occurred: disconnect; the close event handler will trigger a connection retry
logger.error('Failed to write to the Python client connection: ' + e.toString());
try {
pythonClient.close();
}
catch (e2) {
logger.error('Failed to close() the Python client connection: ' + e2.toString());
}
pythonClient = null;
return false;
}
};
var internalTID = 0;
var sendDataToPython = function sendDataToPythontFunc(packetObj) {
var s, key;
if ((typeof packetObj.tid !== 'undefined') && (packetObj.tid !== null)) {
if ((typeof packetObj.tid === 'string') && (packetObj.tid.charAt(0) === 'i')) key = packetObj.tid; // it bears a TID that is marked as internal one, there's only one way to key this
else if (packetObj.sid) key = packetObj.tid + ':' + packetObj.sid;
else key = '' + packetObj.tid;
}
else {
// no TID exists: set the internal one, not being a number, so it differs from GUI TIDs
packetObj.tid = key = 'i' + internalTID;
internalTID++;
}
s = JSON.stringify(packetObj);
s = new Buffer(Buffer.byteLength(s) + ':' + s);
return new Promise(function (resolve, reject) {
var existingResolver = pythonPromises[key];
pythonPromises[key] = {
'created': Date.now(),
'resolve': resolve,
'reject': reject
};
if (!sendPacketToPython(s)) {
// we can't send right now, queue it for later
pythonQueue.push(s);
}
if (existingResolver) {
existingResolver.reject(new Error('Supplanted by a new request with the same TID'));
}
});
};
// this is internal function to python connection handler
var sendPythonQueue = function sendPythonQueueFunc() {
while (pythonQueue.length > 0) {
if (sendPacketToPython(pythonQueue[0])) {
// remove the packet only after it has been successfully sent
pythonQueue.shift();
}
else {
// no more sending possible
break;
}
}
};
var connectPython = function connectPythonFunc() {
var receivingHeader = true, // whether we're receiving the length of the next packet, or the packet itself
receiveBuffer = [], // chunks of the next packet (header or body), Buffer objects
bodyLength = 0, // the required length of the next packet
receivedLength = 0; // the size of the received body inside receiveBuffer up to now
logger.debug('Attempting to connect to Python');
pythonClient = net.connect({
'host': 'localhost',
'port': 19732
});
pythonClient.on('connect', function () {
// login to the python server by sending it the list of currently handled sessions
var sid, sessionList = [], packet;
logger.debug('Connection to Python established');
for (sid in sessions) {
if (sessionList.hasOwnProperty(sid)) {
sessionList.push({'sid': sid, 'lastActivity': sessionList[sid].lastActivity});
}
}
// this should/must succeed in sending right now, as it is the first write ever made on the socket
packet = JSON.stringify({'type': 'connect', 'sessions': sessionList});
packet = new Buffer(Buffer.byteLength(packet) + ':' + packet);
sendPacketToPython(packet);
});
// handler for incoming data, chunk is a Buffer object
pythonClient.on('data', function (chunk) {
var i, s,
offset = 0,
N = chunk.length;
logger.debug('Received a chunk from Python: ' + chunk);
while (offset < N) { // while there's data left to process
if (receivingHeader) {
// receiving the length of the packet
for (i = offset; i < N; i++) {
if (chunk[i] === 58) break; // found a colon?
}
if (i >= N) {
// incomplete header, buffer it for the next 'data' event
s = chunk.slice(offset);
receiveBuffer.push(s);
receivedLength += s.length;
break;
}
if (receiveBuffer.length == 0) bodyLength = +chunk.toString('utf8', offset, i);
else {
s = chunk.slice(offset, i);
receiveBuffer.push(s);
bodyLength = +Buffer.concat(receiveBuffer, receivedLength + s.length).toString('utf8');
receiveBuffer.length = 0;
receivedLength = 0;
}
offset = i + 1;
receivingHeader = false;
continue; // process the packet body in the next iteration
}
else if ((receivedLength + N - offset) >= bodyLength) {
if (receivedLength == 0) {
// an optimization in case the buffer is empty
s = chunk.slice(offset, offset + bodyLength);
offset += s.length;
}
else {
s = chunk.slice(offset, offset + bodyLength - receivedLength);
offset += s.length;
receiveBuffer.push(s);
s = Buffer.concat(receiveBuffer, receivedLength + s.length);
receiveBuffer.length = 0;
receivedLength = 0;
}
receivingHeader = true; // process the packet header in the next iteration
try {
processPacketFromPython(s.toString('utf8'));
}
catch (e) {
logException('Failed to process a packet from Python: ' + e, e);
}
}
else {
// incomplete packet body, buffer it for the next 'data' event
s = chunk.slice(offset);
receiveBuffer.push(s);
receivedLength += s.length;
break;
}
}
});
pythonClient.on('drain', function () {
logger.debug('The Python client connection has been drained, resuming with sending any queued packets');
pythonSaturated = false;
sendPythonQueue();
});
pythonClient.on('end', function () {
logger.debug('The Python peer closed the connection');
pythonClient = null; // make it unavailable for further communication
});
pythonClient.on('error', function () {
logger.debug('There was an error on Python client connection');
pythonClient = null; // make it unavailable for further communication
});
pythonClient.on('close', function () {
logger.debug('The Python client connection was closed, attempting to reconnect after half a second');
setTimeout(connectPython, 500); // reconnect after half a second
});
};
connectPython(); // the initial connection attempt
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