Add account validity check

lib/constants.ts

@@ -24,8 +24,12 @@ export const CREATE_ACCOUNT_ERROR = "Account creation has failed"
 export const FUND_ACCOUNT_ERROR = "Account funding has failed"
 export const MISSING_FUSD_VAULT_ERROR =
   "This account does not have an FUSD vault"
+export const INVALID_NETWORK_ADDRESS_ERROR = (network: Networks) =>
+  `This address is invalid for ${network}, please verify that it is correct.`
 
 export const paths = {
   root: "/",
   fundAccount: "/fund-account",
 }
+
+export const ADDRESS_REGEXP = /^(0x)?[0-9a-fA-F]{16}$/

lib/validate.tsx

@@ -3,6 +3,7 @@ import {
   ACCOUNTS_KEYS_DOCS_URL,
   ADDRESS_FORMAT_ERROR,
   ADDRESS_MISSING_ERROR,
+  ADDRESS_REGEXP,
   GENERATE_KEYS_DOCS_URL,
   PUBLIC_KEY_FORMAT_ERROR,
   PUBLIC_KEY_MISSING_ERROR,
@@ -53,7 +54,7 @@ export const createAccountSchemaServer = yup
 const fundAccountSchemaClientShape = {
   address: yup
     .string()
-    .matches(/^(0x)?([0-9a-f]{16})$/i, () => (
+    .matches(ADDRESS_REGEXP, () => (
       <>
         {ADDRESS_FORMAT_ERROR}{" "}
         <Link href={ACCOUNTS_KEYS_DOCS_URL} target="_blank" variant="underline">

pages/api/fund.ts

@@ -1,7 +1,11 @@
 import * as fcl from "@onflow/fcl"
 import * as t from "@onflow/types"
 import {verify} from "hcaptcha"
-import {FUSD_TYPE, MISSING_FUSD_VAULT_ERROR} from "lib/constants"
+import {
+  FUSD_TYPE,
+  INVALID_NETWORK_ADDRESS_ERROR,
+  MISSING_FUSD_VAULT_ERROR,
+} from "lib/constants"
 import publicConfig from "lib/publicConfig"
 import {NextApiRequest, NextApiResponse} from "next"
 import config from "../../lib/config"
@@ -11,6 +15,12 @@ import {fundAccountSchemaServer} from "../../lib/validate"
 import {verifyAPIKey} from "../../lib/common"
 import {ValidationError} from "yup"
 
+const scriptCheckAccount = `
+  pub fun main(address: Address): Bool {
+    return getAccount(address) != nil
+  }
+`
+
 const scriptCheckFUSDVault = `
   import FUSD from ${publicConfig.contractFUSD}
   import FungibleToken from ${publicConfig.contractFungibleToken}
@@ -44,6 +54,19 @@ export default async function fund(req: NextApiRequest, res: NextApiResponse) {
     const address = fcl.withPrefix(req.body.address) || ""
     const token = req.body.token
 
+    // Validate address
+    const isValidAddress = await fcl.send([
+      fcl.script(scriptCheckAccount),
+      fcl.args([fcl.arg(address, t.Address)]),
+    ])
+
+    if (!isValidAddress) {
+      res
+        .status(400)
+        .json({errors: [INVALID_NETWORK_ADDRESS_ERROR(publicConfig.network)]})
+      return
+    }
+
     if (token === FUSD_TYPE) {
       try {
         const hasFUSDVault = await fcl