fix(rest-api): Adds validSwap validation [SLT-321] (#3247)

* Adds validSwap validation

packages/rest-api/src/routes/swapRoute.ts

@@ -8,6 +8,7 @@ import { isTokenAddress } from '../utils/isTokenAddress'
 import { isTokenSupportedOnChain } from '../utils/isTokenSupportedOnChain'
 import { checksumAddresses } from '../middleware/checksumAddresses'
 import { normalizeNativeTokenAddress } from '../middleware/normalizeNativeTokenAddress'
+import { validSwap } from '../validations/validSwap'
 
 const router = express.Router()
 
@@ -162,6 +163,13 @@ router.get(
       )
       .withMessage('Token not supported on specified chain'),
     check('amount').exists().withMessage('amount is required').isNumeric(),
+    check()
+      .custom((_value, { req }) => {
+        const { chain, fromToken, toToken } = req.query
+
+        return validSwap(chain, fromToken, toToken)
+      })
+      .withMessage('Swap not supported for given tokens'),
   ],
   showFirstValidationError,
   swapController

packages/rest-api/src/tests/swapRoute.test.ts

@@ -3,7 +3,7 @@ import express from 'express'
 
 import swapRoute from '../routes/swapRoute'
 import { NativeGasAddress, ZeroAddress } from '../constants'
-import { DAI, NETH, USDC } from '../constants/bridgeable'
+import { DAI, ETH, NETH, USDC } from '../constants/bridgeable'
 
 const app = express()
 app.use('/swap', swapRoute)
@@ -78,6 +78,21 @@ describe('Swap Route with Real Synapse Service', () => {
     )
   }, 10_000)
 
+  it('should return 400 for invalid fromToken + toToken combo', async () => {
+    const response = await request(app).get('/swap').query({
+      chain: '1',
+      fromToken: ETH.addresses[1],
+      toToken: USDC.addresses[1],
+      amount: '1000',
+    })
+
+    expect(response.status).toBe(400)
+    expect(response.body.error).toHaveProperty(
+      'message',
+      'Swap not supported for given tokens'
+    )
+  })
+
   it('should return 400 for token not supported on specified chain', async () => {
     const response = await request(app).get('/swap').query({
       chain: '1',

packages/rest-api/src/utils/tokenAddressToToken.ts

@@ -16,5 +16,6 @@ export const tokenAddressToToken = (chain: string, tokenAddress: string) => {
     address: tokenAddress,
     symbol: tokenInfo.symbol,
     decimals: tokenInfo.decimals,
+    swappable: tokenInfo.swappable,
   }
 }

packages/rest-api/src/validations/validSwap.ts

@@ -0,0 +1,16 @@
+import { tokenAddressToToken } from '../utils/tokenAddressToToken'
+
+export const validSwap = (
+  chain: number | string,
+  fromToken: string,
+  toToken: string
+) => {
+  const fromTokenInfo = tokenAddressToToken(chain.toString(), fromToken)
+  const toTokenInfo = tokenAddressToToken(chain.toString(), toToken)
+
+  if (!fromTokenInfo || !toTokenInfo) {
+    return false
+  }
+
+  return fromTokenInfo.swappable.includes(toToken)
+}