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index.js
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index.js
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var _ = require('underscore');
var crypto = require('crypto');
function getKey(arr) {
var key = '';
_(arr).each(function (part) {
if (part) {
key += crypto.createHash('sha256').update(part).digest('base64');
}
});
return crypto.createHash('sha256').update(key).digest('base64');
}
var ExpressBrute = module.exports = function (store, options) {
var i;
ExpressBrute.instanceCount++;
this.name = "brute"+ExpressBrute.instanceCount;
_.bindAll(this, 'reset', 'getMiddleware');
// set options
this.options = _.extend({}, ExpressBrute.defaults, options);
if (this.options.minWait < 1) {
this.options.minWait = 1;
}
this.store = store;
// build delays array
this.delays = [this.options.minWait];
while(this.delays[this.delays.length-1] < this.options.maxWait) {
var nextNum = this.delays[this.delays.length-1] + (this.delays.length > 1 ? this.delays[this.delays.length-2] : 0);
this.delays.push(nextNum);
}
this.delays[this.delays.length-1] = this.options.maxWait;
// set default lifetime
if (typeof this.options.lifetime == "undefined") {
this.options.lifetime = (this.options.maxWait/1000)*(this.delays.length + this.options.freeRetries);
this.options.lifetime = Math.ceil(this.options.lifetime);
}
// generate "prevent" middleware
this.prevent = this.getMiddleware();
};
ExpressBrute.prototype.getMiddleware = function (options) {
// standardize input
options = _.extend({}, options);
var keyFunc = options.key;
if (typeof keyFunc !== 'function') {
keyFunc = function (req, res, next) { next(options.key); };
}
var getFailCallback = _.bind(function () {
return typeof options.failCallback === 'undefined' ? this.options.failCallback : options.failCallback;
}, this);
// create middleware
return _.bind(function (req, res, next) {
keyFunc(req, res, _.bind(function (key) {
key = getKey([this.getIPFromRequest(req), this.name, key]);
// attach a simpler "reset" function to req.brute.reset
if (this.options.attachResetToRequest) {
var reset = _.bind(function (callback) {
this.store.reset(key, callback);
}, this);
if (req.brute && req.brute.reset) {
// wrap existing reset if one exists
var oldReset = req.brute.reset;
var newReset = reset;
reset = function (callback) {
oldReset(function () {
newReset(callback);
});
};
}
req.brute = {
reset: reset
};
}
// filter request
this.store.get(key, _.bind(function (err, value) {
if (err) {
throw "Cannot get request count";
}
var count = 0,
delay = 0,
lastValidRequestTime = this.now(),
firstRequestTime = lastValidRequestTime;
if (value) {
count = value.count;
lastValidRequestTime = value.lastRequest.getTime();
firstRequestTime = value.firstRequest.getTime();
var delayIndex = value.count - this.options.freeRetries - 1;
if (delayIndex >= 0) {
if (delayIndex < this.delays.length) {
delay = this.delays[delayIndex];
} else {
delay = this.options.maxWait;
}
}
}
var nextValidRequestTime = lastValidRequestTime+delay,
remainingLifetime = this.options.lifetime || 0;
if (!this.options.refreshTimeoutOnRequest && remainingLifetime > 0) {
remainingLifetime = remainingLifetime - Math.floor((this.now() - firstRequestTime) / 1000);
if (remainingLifetime < 1) {
// it should be expired alredy, treat this as a new request and reset everything
count = 0;
delay = 0;
nextValidRequestTime = firstRequestTime = lastValidRequestTime = this.now();
remainingLifetime = this.options.lifetime || 0;
}
}
if (nextValidRequestTime <= this.now()) {
this.store.set(key, {
count: count+1,
lastRequest: new Date(this.now()),
firstRequest: new Date(firstRequestTime)
}, remainingLifetime, function (err) {
if (err) {
throw "Cannot increment request count";
}
typeof next == 'function' && next();
});
} else {
var failCallback = getFailCallback();
typeof failCallback === 'function' && failCallback(req, res, next, new Date(nextValidRequestTime));
}
}, this));
},this));
}, this);
};
ExpressBrute.prototype.reset = function (ip, key, callback) {
key = getKey([ip, this.name, key]);
this.store.reset(key, callback);
};
ExpressBrute.prototype.now = function () {
return Date.now();
};
ExpressBrute.prototype.getIPFromRequest = function (req) {
if (this.options.proxyDepth && this.options.proxyDepth > 0 && req.get('X-Forwarded-For')) {
var ips = req.get('X-Forwarded-For').split(/ *, */);
if (this.options.proxyDepth < ips.length) {
return ips[ips.length - this.options.proxyDepth - 1];
} else if (ips.length > 1) {
return ips[0];
}
}
return req.connection.remoteAddress;
};
var setRetryAfter = function (res, nextValidRequestDate) {
var secondUntilNextRequest = Math.ceil((nextValidRequestDate.getTime() - Date.now())/1000);
res.header('Retry-After', secondUntilNextRequest);
};
ExpressBrute.FailTooManyRequests = function (req, res, next, nextValidRequestDate) {
setRetryAfter(res, nextValidRequestDate);
res.send(429, {error: {text: "Too many requests in this time frame.", nextValidRequestDate: nextValidRequestDate}});
};
ExpressBrute.FailForbidden = function (req, res, next, nextValidRequestDate) {
setRetryAfter(res, nextValidRequestDate);
res.send(403, {error: {text: "Too many requests in this time frame.", nextValidRequestDate: nextValidRequestDate}});
};
ExpressBrute.FailMark = function (req, res, next, nextValidRequestDate) {
res.status(429);
setRetryAfter(res, nextValidRequestDate);
res.nextValidRequestDate = nextValidRequestDate;
next();
};
ExpressBrute.MemoryStore = require('./lib/MemoryStore');
ExpressBrute.defaults = {
freeRetries: 2,
proxyDepth: 0,
attachResetToRequest: true,
refreshTimeoutOnRequest: true,
minWait: 500,
maxWait: 1000*60*15, // 15 minutes
failCallback: ExpressBrute.FailTooManyRequests
};
ExpressBrute.instanceCount = 0;