redis-sliding-rate-limiter
Version:
Flexible and performant rate limiter based on sliding window algorithm with arbitrary precision
112 lines (111 loc) • 5.07 kB
JavaScript
;
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.createExpressMiddleware = void 0;
const normalizeOptions = (options) => {
for (const e of options.limiters) {
if (!e.hasOwnProperty('overrideKey')) {
e.overrideKey = false;
}
if (!e.hasOwnProperty('overrideLimit')) {
e.overrideLimit = false;
}
if (!e.hasOwnProperty('errorMessage') || !e.errorMessage) {
e.errorMessage = 'Too many requests';
}
}
if (!options.hasOwnProperty('errorStatusCode')) {
options.errorStatusCode = 429;
}
if (!options.hasOwnProperty('setHeaders')) {
options.setHeaders = true;
}
return options;
};
const validateOptions = (options) => {
if (options.limiters.some(e => !e.key && !e.overrideKey)) {
throw new Error(`Limiter requires a key or overrideKey enabled`);
}
if (options.limiters.some(e => e.overrideKey && !e.overrideKeyFn && !options.overrideKeyFn)) {
throw new Error('Limiter with overrideKey enabled requires at least one of limiter-specific or middleware-specific overrideKeyFn function to be defined');
}
if (options.limiters.some(e => e.overrideLimit && !e.overrideLimitFn && !options.overrideLimitFn)) {
throw new Error('Limiter with overrideLimit enabled requires at least one of limiter-specific or middleware-specific overrideLimitFn function to be defined');
}
};
const createExpressMiddleware = (options) => {
// Normalize options
options = normalizeOptions(options);
// Validate options
validateOptions(options);
return (req, res, next) => __awaiter(void 0, void 0, void 0, function* () {
// Check if request should be skipped
if (options.skipFn && options.skipFn(req)) {
return next();
}
for (const middlewareLimiter of options.limiters) {
const { limiter, key, overrideKey, overrideKeyFn, overrideLimit, overrideLimitFn, errorMessage, skipFn, } = middlewareLimiter;
// Check if evaluation should be skipped for the current limiter
if (skipFn && skipFn(req, limiter)) {
continue;
}
// Get Redis key
let redisKey;
if (overrideKey) {
redisKey = overrideKeyFn ? overrideKeyFn(req, limiter) : options.overrideKeyFn(req, limiter);
}
else {
redisKey = key;
}
// Override limit if enabled
if (overrideLimit) {
limiter.limit = overrideLimitFn ? overrideLimitFn(req, limiter) : options.overrideLimitFn(req, limiter);
}
const limiterResponse = yield limiter.get(redisKey);
const { allowed, remaining, firstExpireAtMs, windowExpireAtMs } = limiterResponse;
// Set response headers if enabled
if (options.setHeaders) {
// If provided, use custom function
if (options.setHeadersFn) {
options.setHeadersFn(req, res, limiter, limiterResponse);
}
// Otherwise set default headers
else {
const baseKey = 'X-Rate-Limit';
res.set(`${baseKey}-Remaining-${limiter.name}`, '' + remaining);
res.set(`${baseKey}-First-Expire-${limiter.name}`, '' + firstExpireAtMs);
res.set(`${baseKey}-Reset-${limiter.name}`, '' + windowExpireAtMs);
}
}
// Throttle request
if (!allowed) {
if (options.onThrottleRequest) {
return options.onThrottleRequest(req, res, redisKey);
}
else {
let message = '';
if (errorMessage) {
if (typeof errorMessage === 'string') {
message = errorMessage;
}
else {
message = JSON.stringify(errorMessage);
}
}
return res.status(options.errorStatusCode).send(message);
}
}
}
// Allow request
return next();
});
};
exports.createExpressMiddleware = createExpressMiddleware;