added google recaptcha v2 validator to faucet service

Author: wwwehr

packages/faucet/README.md

@@ -44,29 +44,35 @@ start     Starts the faucet
 
 Environment variables
 
-FAUCET_CONCURRENCY        Number of distributor accounts. Defaults to 5.
-FAUCET_PORT               Port of the webserver. Defaults to 8000.
-FAUCET_MEMO               Memo for send transactions. Defaults to unset.
-FAUCET_GAS_PRICE          Gas price for transactions as a comma separated list.
-                          Defaults to "0.025ucosm".
-FAUCET_GAS_LIMIT          Gas limit for send transactions. Defaults to 100000.
-FAUCET_MNEMONIC           Secret mnemonic that serves as the base secret for the
-                          faucet HD accounts
-FAUCET_PATH_PATTERN       The pattern of BIP32 paths for the faucet accounts.
-                          Must contain one "a" placeholder that is replaced with
-                          the account index.
-                          Defaults to the Cosmos Hub path "m/44'/118'/0'/0/a".
-FAUCET_ADDRESS_PREFIX     The bech32 address prefix. Defaults to "cosmos".
-FAUCET_TOKENS             A comma separated list of token denoms, e.g.
-                          "uatom" or "ucosm, mstake".
-FAUCET_CREDIT_AMOUNT_TKN  Send this amount of TKN to a user requesting TKN. TKN is
-                          a placeholder for the token's denom. Defaults to 10000000.
-FAUCET_REFILL_FACTOR      Send factor times credit amount on refilling. Defauls to 8.
-FAUCET_REFILL_THRESHOLD   Refill when balance gets below factor times credit amount.
-                          Defaults to 20.
-FAUCET_COOLDOWN_TIME      Time (in seconds) after which an address can request
-                          more tokens. Can be set to "0". Defaults to 24 hours
-                          if unset or an empty string.
+FAUCET_CONCURRENCY          Number of distributor accounts. Defaults to 5.
+FAUCET_PORT                 Port of the webserver. Defaults to 8000.
+FAUCET_MEMO                 Memo for send transactions. Defaults to unset.
+FAUCET_GAS_PRICE            Gas price for transactions as a comma separated list.
+                            Defaults to "0.025ucosm".
+FAUCET_GAS_LIMIT            Gas limit for send transactions. Defaults to 100000.
+FAUCET_MNEMONIC             Secret mnemonic that serves as the base secret for the
+                            faucet HD accounts
+FAUCET_PATH_PATTERN         The pattern of BIP32 paths for the faucet accounts.
+                            Must contain one "a" placeholder that is replaced with
+                            the account index.
+                            Defaults to the Cosmos Hub path "m/44'/118'/0'/0/a".
+FAUCET_ADDRESS_PREFIX       The bech32 address prefix. Defaults to "cosmos".
+FAUCET_TOKENS               A comma separated list of token denoms, e.g.
+                            "uatom" or "ucosm, mstake".
+FAUCET_CREDIT_AMOUNT_TKN    Send this amount of TKN to a user requesting TKN. TKN is
+                            a placeholder for the token's denom. Defaults to 10000000.
+FAUCET_REFILL_FACTOR        Send factor times credit amount on refilling. Defauls to 8.
+FAUCET_REFILL_THRESHOLD     Refill when balance gets below factor times credit amount.
+                            Defaults to 20.
+FAUCET_COOLDOWN_TIME        Time (in seconds) after which an address can request
+                            more tokens. Can be set to "0". Defaults to 24 hours
+                            if unset or an empty string.
+GOOGLE_RECAPTCHA_SECRET_KEY The secret key for validating input with the recaptcha v2
+                            service. If this value is set, then each call to the `/credit`
+                            endpoint will require a valid recaptcha response string in
+                            the JSON POST data named `recaptcha` in addition to the `denom`
+                            and `address`.
+                            Defaults to unset (disabled)
 ```
 
 ### Faucet HD wallet
@@ -134,6 +140,14 @@ curl --header "Content-Type: application/json" \
   http://localhost:8000/credit
 ```
 
+### Using the faucet with Recaptcha validation enabled
+```
+curl --header "Content-Type: application/json" \
+  --request POST \
+  --data '{"denom":"ucosm","address":"cosmos1yre6ac7qfgyfgvh58ph0rgw627rhw766y430qq", "recaptcha": "03AFcWeA6KFdGLxDQIx_UZ9Y9IMlAJyen-DkT3k..."}' \
+  http://localhost:8000/credit
+```
+
 ### Checking the faucets status
 
 The faucet provides a simple status check in the form of an http GET request. As

packages/faucet/package.json

@@ -49,7 +49,8 @@
     "@cosmjs/utils": "workspace:^",
     "@koa/cors": "^3.3",
     "koa": "^2.13",
-    "koa-bodyparser": "^4.3"
+    "koa-bodyparser": "^4.3",
+    "undici": "^6.18.2"
   },
   "devDependencies": {
     "@istanbuljs/nyc-config-typescript": "^1.0.1",

packages/faucet/src/api/requestparser.spec.ts

@@ -3,7 +3,11 @@ import { RequestParser } from "./requestparser";
 describe("RequestParser", () => {
   it("can process valid credit request with denom", () => {
     const body = { address: "abc", denom: "utkn" };
-    expect(RequestParser.parseCreditBody(body)).toEqual({ address: "abc", denom: "utkn" });
+    expect(RequestParser.parseCreditBody(body)).toEqual({
+      address: "abc",
+      denom: "utkn",
+      recaptcha: undefined,
+    });
   });
 
   it("throws helpful error message when ticker is found", () => {

packages/faucet/src/api/requestparser.ts

@@ -7,6 +7,8 @@ export interface CreditRequestBodyData {
   readonly denom: string;
   /** The recipient address */
   readonly address: string;
+  /** The recaptcha v2 response */
+  readonly recaptcha: string | undefined;
 }
 
 export interface CreditRequestBodyDataWithTicker {
@@ -22,7 +24,7 @@ export class RequestParser {
       throw new HttpError(400, "Request body must be a dictionary.");
     }
 
-    const { address, denom, ticker } = body as any;
+    const { address, denom, ticker, recaptcha } = body as any;
 
     if (typeof ticker !== "undefined") {
       throw new HttpError(400, "The 'ticker' field was removed in CosmJS 0.23. Please use 'denom' instead.");
@@ -47,6 +49,7 @@ export class RequestParser {
     return {
       address: address,
       denom: denom,
+      recaptcha: recaptcha,
     };
   }
 }

packages/faucet/src/api/webserver.ts

@@ -1,6 +1,8 @@
 import Koa from "koa";
 import cors = require("@koa/cors");
 import bodyParser from "koa-bodyparser";
+import { request } from "undici";
+import qs from "node:querystring";
 
 import { isValidAddress } from "../addresses";
 import * as constants from "../constants";
@@ -59,7 +61,7 @@ export class Webserver {
           // context.request.body is set by the bodyParser() plugin
           const requestBody = (context.request as any).body;
           const creditBody = RequestParser.parseCreditBody(requestBody);
-          const { address, denom } = creditBody;
+          const { address, denom, recaptcha } = creditBody;
 
           if (!isValidAddress(address, constants.addressPrefix)) {
             throw new HttpError(400, "Address is not in the expected format for this chain.");
@@ -82,6 +84,25 @@ export class Webserver {
             throw new HttpError(422, `Token is not available. Available tokens are: ${availableTokens}`);
           }
 
+          // if enabled, require recaptcha validation
+          if (process.env.GOOGLE_RECAPTCHA_SECRET_KEY !== undefined) {
+            const { body } = await request("https://www.google.com/recaptcha/api/siteverify", {
+              method: "POST",
+              headers: {
+                "content-type": "application/x-www-form-urlencoded",
+              },
+              body: qs.stringify({
+                secret: process.env.GOOGLE_RECAPTCHA_SECRET_KEY,
+                response: recaptcha,
+              }),
+            });
+            const verify_data = (await body.json()) as { success: boolean };
+            if (!verify_data.success) {
+              console.error(`recaptcha validation FAILED ${JSON.stringify(verify_data, null, 4)}`);
+              throw new HttpError(423, `Recaptcha failed to verify`);
+            }
+          }
+
           try {
             // Count addresses to prevent draining
             this.addressCounter.set(address, new Date());

yarn.lock

@@ -606,6 +606,7 @@ __metadata:
     source-map-support: ^0.5.19
     ts-node: ^8
     typescript: ~4.9
+    undici: ^6.18.2
     webpack: ^5.76.0
     webpack-cli: ^4.6.0
   bin:
@@ -7697,6 +7698,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"undici@npm:^6.18.2":
+  version: 6.18.2
+  resolution: "undici@npm:6.18.2"
+  checksum: c20e47bd4f959c00d24516756b178190f0a9ae000007e875f1f68c8e7f3f9a68b0a7faa03f3d030ddd71a9e3feb558fbce661b5229a0aa8380cfbe1cea4281e4
+  languageName: node
+  linkType: hard
+
 "unique-filename@npm:^3.0.0":
   version: 3.0.0
   resolution: "unique-filename@npm:3.0.0"