common token disbursal rate limit (#186)

* common token disbursal rate limit

* logging

Author: rajranjan0608

CouponService/couponService.ts

@@ -13,6 +13,7 @@ export type Coupon = {
     reset: boolean,
     skipIpRateLimit?: boolean,
     skipWalletRateLimit?: boolean,
+    skipCommonTokenDisbursalRateLimit?: boolean,
 }
 
 type CouponConfig = {

config.json

@@ -36,6 +36,10 @@
             "RATELIMIT": {
                 "MAX_LIMIT": 1,
                 "WINDOW_SIZE": 1440
+            },
+            "COMMON_TOKEN_DISBURSAL_RL": {
+                "MAX_LIMIT": 20,
+                "WINDOW_SIZE": 60
             }
         },
         {

middlewares/rateLimiter.ts

@@ -5,15 +5,21 @@ import { CouponService } from '../CouponService/couponService'
 
 export class RateLimiter {
     PATH: string
-    type: 'ip' | 'wallet' | 'global'
+    type: 'ip' | 'wallet' | 'global' | 'common_token_disbursal'
 
     constructor(
         app: any,
         configs: RateLimiterConfig[],
-        type: 'ip' | 'wallet' | 'global',
+        type: 'ip' | 'wallet' | 'global' | 'common_token_disbursal',
         couponService: CouponService,
         keyGenerator?: any,
     ) {
+        if (configs.length === 0) {
+            this.PATH = '/api/sendToken'
+            this.type = 'common_token_disbursal'
+            return
+        }
+
         this.PATH = configs[0].RATELIMIT.PATH || '/api/sendToken'
         this.type = type
 
@@ -27,7 +33,7 @@ export class RateLimiter {
                 SKIP_FAILED_REQUESTS: RATELIMIT.SKIP_FAILED_REQUESTS || true,
             }
 
-            rateLimiters.set(config.ID, this.getLimiter(RL_CONFIG, keyGenerator))
+            rateLimiters.set(config.ID, this.getLimiter(RL_CONFIG, config.ID, type, keyGenerator))
         })
 
         if(configs[0]?.RATELIMIT?.REVERSE_PROXIES) {
@@ -43,6 +49,8 @@ export class RateLimiter {
                     return next()
                 } else if (this.type === 'wallet' && coupon && coupon.skipWalletRateLimit) {
                     return next()
+                } else if (this.type === 'common_token_disbursal' && coupon && coupon.skipCommonTokenDisbursalRateLimit) {
+                    return next()
                 }
             }
 
@@ -54,15 +62,30 @@ export class RateLimiter {
         })
     }
 
-    getLimiter(config: any, keyGenerator?: any): RateLimitRequestHandler {
+    getLimiter(
+        config: any,
+        faucetConfigId: string,
+        type: 'ip' | 'wallet' | 'global' | 'common_token_disbursal',
+        keyGenerator?: any,
+    ): RateLimitRequestHandler {
         const limiter = rateLimit({
             windowMs: config.WINDOW_SIZE * 60 * 1000,
             max: config.MAX_LIMIT,
             standardHeaders: true,
             legacyHeaders: false,
             skipFailedRequests: config.SKIP_FAILED_REQUESTS,
-            message: {
-                message: `Too many requests. Please try again after ${config.WINDOW_SIZE} minutes`
+            handler: (req, res, next, options) => {
+                if(type === 'common_token_disbursal') {
+                    console.log(JSON.stringify({
+                        date: new Date(),
+                        type: "CommonTokenDisbursalRateLimit",
+                        faucetConfigId,
+                        ip: req.headers["cf-connecting-ip"] || req.ip
+                    }))
+                }
+                res.status(options.statusCode).send({
+                    message: `Too many requests. Please try again after ${config.WINDOW_SIZE} minutes`
+                })
             },
             keyGenerator: keyGenerator ? keyGenerator : (req, res) => {
                 const ip = this.getIP(req)

server.ts

@@ -10,6 +10,8 @@ import {
     SendTokenResponse,
     ChainType,
     EVMInstanceAndConfig,
+    ERC20Type,
+    RateLimiterConfig,
 } from './types'
 
 import {
@@ -50,6 +52,23 @@ const mainnetCheckService = new MainnetCheckService(MAINNET_BALANCE_CHECK_RPC)
 
 new RateLimiter(app, [GLOBAL_RL], 'global', couponService)
 
+// create array of common token disbursal rate limiter config from evmchains.COMMON_TOKEN_DISBURSAL_RL
+const commonTokenDisbursalRl = [...evmchains, ...erc20tokens].map((chain: ChainType | ERC20Type) => {
+    if (chain.COMMON_TOKEN_DISBURSAL_RL) {
+        return {
+            ID: chain.ID,
+            RATELIMIT: {
+                MAX_LIMIT: chain.COMMON_TOKEN_DISBURSAL_RL.MAX_LIMIT,
+                WINDOW_SIZE: chain.COMMON_TOKEN_DISBURSAL_RL.WINDOW_SIZE,
+            }
+        }
+    }
+}).filter(Boolean) as RateLimiterConfig[]
+new RateLimiter(app, commonTokenDisbursalRl, 'common_token_disbursal', couponService, (req: any, res: any) => {
+    // this common key will be used for all user requests allowing a unified rate limit.
+    return 'global'
+})
+
 new RateLimiter(app, [
     ...evmchains,
     ...erc20tokens

types.ts

@@ -41,6 +41,10 @@ export type ChainType = {
     RATELIMIT: {
         WINDOW_SIZE: number,
         MAX_LIMIT: number
+    },
+    COMMON_TOKEN_DISBURSAL_RL?: {
+        WINDOW_SIZE: number,
+        MAX_LIMIT: number
     }
 }
 
@@ -57,6 +61,10 @@ export type ERC20Type = {
         WINDOW_SIZE: number,
         MAX_LIMIT: number
     },
+    COMMON_TOKEN_DISBURSAL_RL?: {
+        WINDOW_SIZE: number,
+        MAX_LIMIT: number
+    },
     IMAGE?: string,
     RECALIBRATE?: number,
     RPC?: string,