feat: check callback error signature

src/farcaster-client/index.ts

@@ -58,6 +58,10 @@ export interface ICallbackDataCheck extends IAddressesInfo {
    * Auth service proof signature
    */
   proof: string
+  /**
+   * Error message in case of failure
+   */
+  errorMessage?: string
 }
 
 export class FarcasterClient {
@@ -207,7 +211,12 @@ export class FarcasterClient {
 
     if (
       (await extractSignerAddress(
-        DelegatedFs.getDelegatedText(data.userMainAddress, data.userDelegatedAddress, expectedApplicationAddress),
+        DelegatedFs.getDelegatedText(
+          data.userMainAddress,
+          data.userDelegatedAddress,
+          expectedApplicationAddress,
+          data.errorMessage,
+        ),
         data.proof,
       )) !== expectedAuthServiceAddress
     ) {

src/service/delegated-fs/delegated-fs.ts

@@ -43,8 +43,14 @@ export class DelegatedFs {
    * @param userAddress User address
    * @param userDelegatedAddress User delegated address
    * @param applicationAddress Application address
+   * @param errorText Error text
    */
-  static getDelegatedText(userAddress: string, userDelegatedAddress: string, applicationAddress: string): string {
+  static getDelegatedText(
+    userAddress: string,
+    userDelegatedAddress: string,
+    applicationAddress: string,
+    errorText?: string,
+  ): string {
     userAddress = prepareEthAddress(userAddress)
     userDelegatedAddress = prepareEthAddress(userDelegatedAddress)
     applicationAddress = prepareEthAddress(applicationAddress)
@@ -54,7 +60,13 @@ export class DelegatedFs {
       throw new Error('Delegated text addresses must be unique')
     }
 
-    return `${userAddress}${userDelegatedAddress}${applicationAddress}`
+    let text = `${userAddress}${userDelegatedAddress}${applicationAddress}`
+
+    if (errorText) {
+      text = `ERROR${text}${errorText}`
+    }
+
+    return text
   }
 
   /**
@@ -63,15 +75,19 @@ export class DelegatedFs {
    * @param userDelegatedAddress User delegated address
    * @param applicationAddress Application address
    * @param signer Signer
+   * @param errorText Error text
    */
   static async createDelegateSignature(
     userAddress: string,
     userDelegatedAddress: string,
     applicationAddress: string,
     signer: ISigner,
+    errorText?: string,
   ): Promise<string> {
     return prepareEthSignature(
-      await signer.signMessage(DelegatedFs.getDelegatedText(userAddress, userDelegatedAddress, applicationAddress)),
+      await signer.signMessage(
+        DelegatedFs.getDelegatedText(userAddress, userDelegatedAddress, applicationAddress, errorText),
+      ),
     )
   }
 }

test/farcaster-client/check-callback-data.test.ts

@@ -0,0 +1,123 @@
+import { createSdk } from '../utils/sdk'
+import { optimismMainnetConfig } from '../../src/network-config'
+import { Wallet } from 'ethers'
+import { ICallbackDataCheck } from '../../src/farcaster-client'
+import { DelegatedFs } from '../../src/service/delegated-fs/delegated-fs'
+
+describe('Farcaster Client', () => {
+  it('should check correct callback data', async () => {
+    const sdk = await createSdk(optimismMainnetConfig, Wallet.createRandom())
+
+    const userMainWallet = Wallet.createRandom()
+    const userDelegatedWallet = Wallet.createRandom()
+    const applicationWallet = Wallet.createRandom()
+    const authServiceWallet = Wallet.createRandom()
+
+    const proof = await DelegatedFs.createDelegateSignature(
+      userMainWallet.address,
+      userDelegatedWallet.address,
+      applicationWallet.address,
+      authServiceWallet,
+    )
+
+    const dataToCheck: ICallbackDataCheck = {
+      userMainAddress: userMainWallet.address,
+      userDelegatedAddress: userDelegatedWallet.address,
+      applicationAddress: applicationWallet.address,
+      proof,
+    }
+
+    await expect(
+      sdk.farcasterClient.checkCallbackData(dataToCheck, applicationWallet.address, authServiceWallet.address),
+    ).resolves.toBeUndefined()
+  })
+
+  it('should throw on incorrect callback data', async () => {
+    const sdk = await createSdk(optimismMainnetConfig, Wallet.createRandom())
+
+    const userMainWallet = Wallet.createRandom()
+    const userDelegatedWallet = Wallet.createRandom()
+    const applicationWallet = Wallet.createRandom()
+    const authServiceWallet = Wallet.createRandom()
+
+    const proof = await DelegatedFs.createDelegateSignature(
+      userMainWallet.address,
+      userDelegatedWallet.address,
+      applicationWallet.address,
+      // incorrect signer
+      applicationWallet,
+    )
+
+    const dataToCheck: ICallbackDataCheck = {
+      userMainAddress: userMainWallet.address,
+      userDelegatedAddress: userDelegatedWallet.address,
+      applicationAddress: applicationWallet.address,
+      proof,
+    }
+
+    await expect(
+      sdk.farcasterClient.checkCallbackData(dataToCheck, applicationWallet.address, authServiceWallet.address),
+    ).rejects.toThrow('Invalid proof')
+  })
+
+  it('should check correct callback data with error', async () => {
+    const sdk = await createSdk(optimismMainnetConfig, Wallet.createRandom())
+
+    const userMainWallet = Wallet.createRandom()
+    const userDelegatedWallet = Wallet.createRandom()
+    const applicationWallet = Wallet.createRandom()
+    const authServiceWallet = Wallet.createRandom()
+
+    const errorMessage = 'My Custom Error'
+
+    const proofError = await DelegatedFs.createDelegateSignature(
+      userMainWallet.address,
+      userDelegatedWallet.address,
+      applicationWallet.address,
+      authServiceWallet,
+      errorMessage,
+    )
+
+    const dataToCheckError: ICallbackDataCheck = {
+      userMainAddress: userMainWallet.address,
+      userDelegatedAddress: userDelegatedWallet.address,
+      applicationAddress: applicationWallet.address,
+      proof: proofError,
+      errorMessage,
+    }
+
+    await expect(
+      sdk.farcasterClient.checkCallbackData(dataToCheckError, applicationWallet.address, authServiceWallet.address),
+    ).resolves.toBeUndefined()
+  })
+
+  it('should throw with incorrect error', async () => {
+    const sdk = await createSdk(optimismMainnetConfig, Wallet.createRandom())
+
+    const userMainWallet = Wallet.createRandom()
+    const userDelegatedWallet = Wallet.createRandom()
+    const applicationWallet = Wallet.createRandom()
+    const authServiceWallet = Wallet.createRandom()
+
+    const errorMessage = 'My Custom Error'
+    const proofError = await DelegatedFs.createDelegateSignature(
+      userMainWallet.address,
+      userDelegatedWallet.address,
+      applicationWallet.address,
+      authServiceWallet,
+      errorMessage,
+    )
+
+    const dataToCheckError: ICallbackDataCheck = {
+      userMainAddress: userMainWallet.address,
+      userDelegatedAddress: userDelegatedWallet.address,
+      applicationAddress: applicationWallet.address,
+      proof: proofError,
+      errorMessage,
+    }
+
+    await expect(
+      sdk.farcasterClient.checkCallbackData(dataToCheckError, applicationWallet.address, authServiceWallet.address),
+    ).resolves.toBeUndefined()
+  })
+})

test/manual/delegatedFs.js

@@ -137,7 +137,7 @@ async function getAuthProofByAddress() {
 
   const proofData = await sdkMainnet.farcasterClient.getAuthProofByAddress(getUserAddress(), getApplicationAddress())
   try {
-    sdkMainnet.farcasterClient.checkCallbackData(
+    await sdkMainnet.farcasterClient.checkCallbackData(
       {
         userMainAddress: proofData.userMainAddress,
         userDelegatedAddress: proofData.userDelegatedAddress,