The Memo Transfer Extension

Name: Token2022 with Web3.js
Availability: InStock

The MemoTranfer Extension is a Token account extension that enforces that all incoming transfers to a token account include a memo, facilitating enhanced transaction tracking and user identification.

Initializing the Token Account

To initialize the MemoTransfer extension on a Token account we're going to need the enableRequiredMemoTransfers() function.

Here's how to create a token with the Memo Transfer Extension:

import { Keypair, SystemProgram, Transaction, sendAndConfirmTransaction } from "@solana/web3.js";
import {
  createInitializeAccountInstruction,
  createEnableRequiredMemoTransfersInstruction,
  getAccountLen,
  ExtensionType,
  TOKEN_2022_PROGRAM_ID,
} from "@solana/spl-token";

const tokenAccount = Keypair.generate();

// Calculate the size needed for a Token account with Memo Transfer extension
const accountLen = getAccountLen([ExtensionType.MemoTransfer]);

// Calculate minimum lamports required for rent exemption
const lamports = await connection.getMinimumBalanceForRentExemption(accountLen);

// Create the account with the correct size and owner
const createAccountInstruction = SystemProgram.createAccount({
  fromPubkey: keypair.publicKey,
  newAccountPubkey: tokenAccount.publicKey,
  space: accountLen,
  lamports,
  programId: TOKEN_2022_PROGRAM_ID,
});

// Initialize the Memo Transfer extension
const enableMemoTransferInstruction = createEnableRequiredMemoTransfersInstruction(
  destinationTokenAccount.publicKey,
  destinationKeypair.publicKey,
  undefined,
  TOKEN_2022_PROGRAM_ID,
);

// Initialize the Token account itself
const initializeAccountInstruction = createInitializeAccountInstruction(
  tokenAccount.publicKey,
  mint.publicKey,
  keypair.publicKey,
  TOKEN_2022_PROGRAM_ID,
);

const transaction = new Transaction().add(
  createAccountInstruction,
  initializeAccountInstruction,
  enableMemoTransferInstruction,
);

const signature = await sendAndConfirmTransaction(
  connection,
  transaction,
  [keypair, tokenAccount],
  { skipPreflight: false },
);

console.log(
  `Token accounts created! Check out your TX here: https://explorer.solana.com/tx/${signature}?cluster=devnet`,
);

Expand

[43 more lines]

Transferring Token with a Memo

To use the Memo program on Solana we have two viable path.

Building our own "raw" memo instruction like this:

const message = "Hello, Solana";

new TransactionInstruction({
    keys: [{ pubkey: keypair.publicKey, isSigner: true, isWritable: true }],
    data: Buffer.from(message, "utf-8"), // Memo message. In this case it is "Hello, Solana"
    programId: new PublicKey("MemoSq4gqABAXKb96qnH8TysNcWxMyWCqXgDLGmfcHr"), // Memo program that validates keys and memo message
}),

Or we can use the Memo program SDK after downloading the package like this:

text

npm i @solana/spl-memo

In our example we're going to use the second option and it will look like this:

const memoInstruction = createMemoInstruction("Hello, world!", [keypair.publicKey]);

const transferInstruction = createTransferCheckedInstruction(
  tokenAccount,
  mint.publicKey,
  destinationTokenAccount.publicKey,
  keypair.publicKey,
  BigInt(100e6),
  6,
  undefined,
  TOKEN_2022_PROGRAM_ID,
);

const transferTransaction = new Transaction().add(memoInstruction, transferInstruction);

const transferSignature = await sendAndConfirmTransaction(connection, transferTransaction, [
  keypair,
]);

console.log(
  `Tokens transferred with memo! Check out your TX here: https://explorer.solana.com/tx/${transferSignature}?cluster=devnet`,
);

Expand

[7 more lines]

Disabling and Enabling the Memo

If we don't want to enforce the transfer to come with a memo, we can do so using the disableRequiredMemoTransfer function and it would look like so:

const disableRequiredMemoTransfersInstruction = createDisableRequiredMemoTransfersInstruction(
  destinationTokenAccount,
  destinationKeypair.publicKey,
  undefined,
  TOKEN_2022_PROGRAM_ID,
);

const transferInstruction = createTransferCheckedInstruction(
  tokenAccount,
  mint.publicKey,
  destinationTokenAccount,
  keypair.publicKey,
  BigInt(100e6),
  6,
  undefined,
  TOKEN_2022_PROGRAM_ID,
);

const transaction = new Transaction().add(
  disableRequiredMemoTransfersInstruction,
  transferInstruction,
);

const signature = await sendAndConfirmTransaction(connection, transaction, [
  keypair,
  destinationKeypair,
]);

console.log(
  `Tokens transferred and account state changed! Check out your TX here: https://explorer.solana.com/tx/${signature}?cluster=devnet`,
);

Expand

[16 more lines]

And if we want to enable it back we can just use the enableRequiredMemoTransfers() function like this:

const enableRequiredMemoTransfersInstruction = createEnableRequiredMemoTransfersInstruction(
  destinationTokenAccount,
  destinationKeypair.publicKey,
  undefined,
  TOKEN_2022_PROGRAM_ID,
);

const transferInstruction = createTransferCheckedInstruction(
  tokenAccount,
  mint.publicKey,
  destinationTokenAccount,
  keypair.publicKey,
  BigInt(100e6),
  6,
  undefined,
  TOKEN_2022_PROGRAM_ID,
);

const transaction = new Transaction().add(
  enableRequiredMemoTransfersInstruction,
  transferInstruction,
);

const signature = await sendAndConfirmTransaction(connection, transaction, [
  keypair,
  destinationKeypair,
]);

console.log(
  `Tokens transferred and account state changed! Check out your TX here: https://explorer.solana.com/tx/${signature}?cluster=devnet`,
);

Expand

[16 more lines]