fix(smart-wallet-sdk): add parseAddressDelegation (#344)

Author: zhongeric

sdks/smart-wallet-sdk/src/constants.ts

@@ -1,5 +1,8 @@
 import { ChainId } from '@uniswap/sdk-core'
 
+// https://eips.ethereum.org/EIPS/eip-7702
+export const DELEGATION_MAGIC_PREFIX = '0xef0100';
+
 /**
  * The target address for self-calls is address(0)
  */

sdks/smart-wallet-sdk/src/utils/delegation.test.ts

@@ -0,0 +1,26 @@
+import { DELEGATION_MAGIC_PREFIX } from "../constants";
+
+import { Delegation } from "./delegation";
+
+
+describe('Delegation', () => {
+    describe('parseFromCode', () => {
+        const address = `1111111111111111111111111111111111111111`; // address length without 0x prefix
+        it('parses out the delegation', () => {
+          const delegation = Delegation.parseFromCode(`${DELEGATION_MAGIC_PREFIX}${address}`);
+          expect(delegation).toBe(`0x${address}`)
+        })
+    
+        it('throws an error if there is no delegation', () => {
+          const emptyDelegation = '' as `0x${string}`;
+          expect(() => Delegation.parseFromCode(emptyDelegation)).toThrow()
+        })
+    
+        it('throws an error if the magic prefix is incorrect', () => {
+          const incorrectMagicPrefix = '0x000000' as `0x${string}`;
+          expect(() => Delegation.parseFromCode(`${incorrectMagicPrefix}${address}`)).toThrow(
+            `Invalid delegation magic prefix: ${incorrectMagicPrefix}`
+          )
+        })
+    })
+})

sdks/smart-wallet-sdk/src/utils/delegation.ts

@@ -0,0 +1,48 @@
+import { Address, TransactionEIP7702 } from 'viem'
+import { recoverAuthorizationAddress, SignedAuthorization, SignedAuthorizationList } from 'viem/experimental'
+
+import { DELEGATION_MAGIC_PREFIX } from '../constants'
+
+export type RecoveredAuthorizationMap = Record<Address, SignedAuthorization>
+
+export class Delegation {
+    /**
+     * Recovers the signers of each authorization within the list sent in the transaction
+     * @dev this can also return just the contractAddress each signer is delegated to
+     * @param transaction : TransactionEIP7702
+     * @returns : Promise<RecoveredAuthorizationMap>
+     */
+    public static parseAuthorizationListFromTransaction(transaction: TransactionEIP7702): Promise<RecoveredAuthorizationMap> {
+        return this.parseAuthorizationList(transaction.authorizationList)
+    }
+
+    /**
+     * Recovers the signers of each authorization in the list
+     * @param authorizationList : SignedAuthorizationList
+     * @returns : Promise<RecoveredAuthorizationMap>
+     */
+    public static async parseAuthorizationList(authorizationList: SignedAuthorizationList): Promise<RecoveredAuthorizationMap> {
+        // recover each authorization
+        const result: RecoveredAuthorizationMap = {}
+        for (const authorization of authorizationList) {
+            const signer = await recoverAuthorizationAddress({ authorization })
+            result[signer] = authorization
+        }
+        return result
+    }
+
+    /// Parses a delegation from an address's code
+    /// @dev will throw if the code is not a valid delegation per EIP7702 spec
+    public static parseFromCode(code: `0x${string}`): Address {
+        if(code.length !== 48) {
+          throw new Error(`Invalid delegation length: ${code.length}`)
+        }
+        // parse out magic prefix which is 4 bytes
+        const magicPrefix = code.slice(0, 8)
+        if(magicPrefix !== DELEGATION_MAGIC_PREFIX) {
+          throw new Error(`Invalid delegation magic prefix: ${magicPrefix}`)
+        }
+        const delegation = code.slice(8)
+        return `0x${delegation}` as Address
+    }
+}