Allow token transfer -- SPL token policy example

packages/solana/package.json

@@ -48,6 +48,7 @@
     "typecheck": "tsc -p tsconfig.typecheck.json"
   },
   "dependencies": {
+    "@solana/spl-token": "^0.4.8",
     "@solana/web3.js": "^1.88.1",
     "@turnkey/http": "workspace:*",
     "@turnkey/sdk-browser": "workspace:*",

packages/solana/src/index.ts

@@ -1,4 +1,5 @@
 import { PublicKey, Transaction, VersionedTransaction } from "@solana/web3.js";
+import { getAssociatedTokenAddressSync } from "@solana/spl-token";
 import {
   assertNonNull,
   assertActivityCompleted,
@@ -131,6 +132,24 @@ export class TurnkeySigner {
     return recoveredTransaction;
   }
 
+  /**
+   * This function derives a Solana associated token address for a given Solana wallet address, related to a particular token mint address
+   *
+   * @param walletAddress string representation of the Solana wallet address (base58 encoded)
+   * @param mintAddress string representation of the token mint address (base58 encoded)
+   */
+  public getAssociatedTokenAddress(mintAddress: string, walletAddress: string) {
+    const mintPublicKey = new PublicKey(mintAddress);
+    const walletPublicKey = new PublicKey(walletAddress);
+
+    const associatedTokenAddress = getAssociatedTokenAddressSync(
+      mintPublicKey,
+      walletPublicKey
+    );
+
+    return associatedTokenAddress.toString();
+  }
+
   private async signTransactionImpl(
     unsignedTransaction: string,
     signWith: string,