feat: helper for rate limits

Author: Thomas-Heniart

.npmrc

@@ -0,0 +1,2 @@
+foreground-scripts=true
+ignore-scripts=true

config/facs/redis.config.json

@@ -0,0 +1,14 @@
+{
+  "sk0": {
+    "host": "127.0.0.1",
+    "port": 6379
+  },
+  "uc0": {
+    "host": "127.0.0.1",
+    "port": 6379
+  },
+  "test": {
+    "host": "127.0.0.1",
+    "port": 6380
+  }
+}

libs/redis.rate.limiter.js

@@ -0,0 +1,55 @@
+'use strict'
+
+const crypto = require('crypto')
+const { GrcUserError, GrcGenericError } = require('@bitfinex/lib-util-err-js')
+
+const RATE_LIMIT_LUA = `
+    local attempts = redis.call('INCR', KEYS[1])
+    if attempts == 1 then
+      redis.call('EXPIRE', KEYS[1], ARGV[1])
+    end
+    return attempts
+  `
+
+class RedisRateLimiterUtil {
+  static register ({ redis, command, keyPrefix, logError }) {
+    return new RedisRateLimiterUtil({ redis, command, keyPrefix, logError })._register()
+  }
+
+  constructor ({ redis, command, keyPrefix, logError }) {
+    this._redis = redis
+    this._command = command
+    this._keyPrefix = keyPrefix
+    this._logError = logError
+    this._registered = false
+  }
+
+  async checkRateLimit (key, expiry, maxAttempts) {
+    if (!this._registered) return this._logError(new GrcGenericError('RedisRateLimiter not registered'))
+    const attempts = await this._redis[this._command](`${this._keyPrefix}:${key}`, expiry)
+    if (attempts > maxAttempts) {
+      throw new GrcUserError('ERR_RATE_LIMIT_EXCEEDED')
+    }
+  }
+
+  _register () {
+    const md5 = crypto.createHash('md5').update(RATE_LIMIT_LUA, 'utf8').digest('hex')
+    const commandSymbol = Symbol.for(this._command)
+    if (this._redis[this._command] || this._redis[commandSymbol] === md5) return this
+    try {
+      this._redis.defineCommand(this._command, {
+        numberOfKeys: 1,
+        lua: RATE_LIMIT_LUA
+      })
+      this._redis[commandSymbol] = md5
+      this._registered = true
+    } catch (error) {
+      this._logError(error)
+    }
+    return this
+  }
+}
+
+module.exports = {
+  RedisRateLimiterUtil
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@bitfinex/bfx-facs-redis",
-  "version": "1.0.0",
+  "version": "1.0.1",
   "private": false,
   "description": "Bitfinex Redis Facility",
   "author": {
@@ -13,6 +13,7 @@
   ],
   "dependencies": {
     "@bitfinex/bfx-facs-base": "git+https://github.com/bitfinexcom/bfx-facs-base.git",
+    "@bitfinex/lib-util-err-js": "git+https://github.com/bitfinexcom/lib-util-err-js.git",
     "async": "^3.2.1",
     "ioredis": "^5.3.0",
     "lodash": "^4.17.21"
@@ -30,5 +31,14 @@
       "name": "prdn",
       "email": "paolo@bitfinex.com"
     }
-  ]
+  ],
+  "devDependencies": {
+    "chai": "4.5.0",
+    "chai-as-promised": "7.1.2",
+    "mocha": "10.8.2",
+    "standard": "17.1.2"
+  },
+  "scripts": {
+    "test": "NODE_ENV=test mocha -R spec -b --recursive --timeout 10000 test"
+  }
 }

test/itgr/redis.rate.limiter.itgr.test.js

@@ -0,0 +1,52 @@
+/* eslint-env mocha */
+
+'use strict'
+
+const chai = require('chai')
+const chaiAsPromised = require('chai-as-promised')
+chai.use(chaiAsPromised)
+
+const { expect } = require('chai')
+const RedisFacility = require('../../index')
+const { RedisRateLimiterUtil } = require('../../libs/redis.rate.limiter')
+
+describe('Redis Rate Limiter Integration', () => {
+  let redisFacility, redis, redisRateLimiter
+
+  before(async () => {
+    redisFacility = new RedisFacility({ ctx: { root: './' } }, {}, {})
+    await new Promise(resolve => redisFacility.start(() => resolve()))
+    redis = redisFacility.cli_rw
+  })
+
+  after(async () => {
+    await new Promise(resolve => redisFacility.stop(() => resolve()))
+  })
+
+  beforeEach(async () => {
+    await redis.flushdb()
+    redisRateLimiter = RedisRateLimiterUtil.register({
+      redis,
+      command: 'bfxRateLimit',
+      keyPrefix: 'bfx',
+      logError: console.error
+    })
+  })
+
+  it('should check rate limit', async () => {
+    await redisRateLimiter.checkRateLimit('some-key', 1, 1)
+    await expect(redisRateLimiter.checkRateLimit('some-key', 1, 1))
+      .to.be.rejectedWith('ERR_RATE_LIMIT_EXCEEDED')
+  })
+
+  it('should reset rate limit after some time', async () => {
+    await redisRateLimiter.checkRateLimit('another-key', 1, 1)
+    await sleep(1100)
+    await redisRateLimiter.checkRateLimit('another-key', 1, 1)
+    expect(true).to.deep.eq(true)
+  })
+
+  const sleep = (ms) => new Promise((resolve) => {
+    setTimeout(() => resolve(), ms)
+  })
+})