feat: add getAddressLookupTable method to Connection

web3.js/src/account-data.ts

@@ -0,0 +1,39 @@
+import * as BufferLayout from '@solana/buffer-layout';
+
+export interface IAccountStateData {
+  readonly typeIndex: number;
+}
+
+/**
+ * @internal
+ */
+export type AccountType<TInputData extends IAccountStateData> = {
+  /** The account type index (from solana upstream program) */
+  index: number;
+  /** The BufferLayout to use to build data */
+  layout: BufferLayout.Layout<TInputData>;
+};
+
+/**
+ * Decode account data buffer using an AccountType
+ * @internal
+ */
+export function decodeData<TAccountStateData extends IAccountStateData>(
+  type: AccountType<TAccountStateData>,
+  data: Uint8Array,
+): TAccountStateData {
+  let decoded: TAccountStateData;
+  try {
+    decoded = type.layout.decode(data);
+  } catch (err) {
+    throw new Error('invalid instruction; ' + err);
+  }
+
+  if (decoded.typeIndex !== type.index) {
+    throw new Error(
+      `invalid account data; account type mismatch ${decoded.typeIndex} != ${type.index}`,
+    );
+  }
+
+  return decoded;
+}

web3.js/src/connection.ts

@@ -24,7 +24,6 @@ import type {Struct} from 'superstruct';
 import {Client as RpcWebSocketClient} from 'rpc-websockets';
 import RpcClient from 'jayson/lib/client/browser';
 
-import {URL} from './utils/url-impl';
 import {AgentManager} from './agent-manager';
 import {EpochSchedule} from './epoch-schedule';
 import {SendTransactionError, SolanaJSONRPCError} from './errors';
@@ -35,6 +34,7 @@ import {Signer} from './keypair';
 import {MS_PER_SLOT} from './timing';
 import {Transaction, TransactionStatus} from './transaction';
 import {Message} from './message';
+import {AddressLookupTableAccount} from './programs/address-lookup-table/state';
 import assert from './utils/assert';
 import {sleep} from './utils/sleep';
 import {toBuffer} from './utils/to-buffer';
@@ -43,6 +43,7 @@ import {
   TransactionExpiredTimeoutError,
 } from './transaction/expiry-custom-errors';
 import {makeWebsocketUrl} from './utils/makeWebsocketUrl';
+import {URL} from './utils/url-impl';
 import type {Blockhash} from './blockhash';
 import type {FeeCalculator} from './fee-calculator';
 import type {TransactionSignature} from './transaction';
@@ -4218,6 +4219,29 @@ export class Connection {
     return res.result;
   }
 
+  async getAddressLookupTable(
+    accountKey: PublicKey,
+    config?: GetAccountInfoConfig,
+  ): Promise<RpcResponseAndContext<AddressLookupTableAccount | null>> {
+    const {context, value: accountInfo} = await this.getAccountInfoAndContext(
+      accountKey,
+      config,
+    );
+
+    let value = null;
+    if (accountInfo !== null) {
+      value = new AddressLookupTableAccount({
+        key: accountKey,
+        state: AddressLookupTableAccount.deserialize(accountInfo.data),
+      });
+    }
+
+    return {
+      context,
+      value,
+    };
+  }
+
   /**
    * Fetch the contents of a Nonce account from the cluster, return with context
    */

web3.js/src/programs/address-lookup-table.ts → web3.js/src/programs/address-lookup-table/index.ts

@@ -1,12 +1,14 @@
 import {toBufferLE} from 'bigint-buffer';
 import * as BufferLayout from '@solana/buffer-layout';
 
-import * as Layout from '../layout';
-import {PublicKey} from '../publickey';
-import * as bigintLayout from '../utils/bigint';
-import {SystemProgram} from './system';
-import {TransactionInstruction} from '../transaction';
-import {decodeData, encodeData, IInstructionInputData} from '../instruction';
+import * as Layout from '../../layout';
+import {PublicKey} from '../../publickey';
+import * as bigintLayout from '../../utils/bigint';
+import {SystemProgram} from '../system';
+import {TransactionInstruction} from '../../transaction';
+import {decodeData, encodeData, IInstructionInputData} from '../../instruction';
+
+export * from './state';
 
 export type CreateLookupTableParams = {
   /** Account used to derive and control the new address lookup table. */

web3.js/src/programs/address-lookup-table/state.ts

@@ -0,0 +1,84 @@
+import * as BufferLayout from '@solana/buffer-layout';
+
+import assert from '../../utils/assert';
+import * as Layout from '../../layout';
+import {PublicKey} from '../../publickey';
+import {u64} from '../../utils/bigint';
+import {decodeData} from '../../account-data';
+
+export type AddressLookupTableState = {
+  deactivationSlot: bigint;
+  lastExtendedSlot: number;
+  lastExtendedSlotStartIndex: number;
+  authority?: PublicKey;
+  addresses: Array<PublicKey>;
+};
+
+export type AddressLookupTableAccountArgs = {
+  key: PublicKey;
+  state: AddressLookupTableState;
+};
+
+/// The serialized size of lookup table metadata
+const LOOKUP_TABLE_META_SIZE = 56;
+
+export class AddressLookupTableAccount {
+  key: PublicKey;
+  state: AddressLookupTableState;
+
+  constructor(args: AddressLookupTableAccountArgs) {
+    this.key = args.key;
+    this.state = args.state;
+  }
+
+  isActive(): boolean {
+    const U64_MAX = 2n ** 64n - 1n;
+    return this.state.deactivationSlot === U64_MAX;
+  }
+
+  static deserialize(accountData: Uint8Array): AddressLookupTableState {
+    const meta = decodeData(LookupTableMetaLayout, accountData);
+
+    const serializedAddressesLen = accountData.length - LOOKUP_TABLE_META_SIZE;
+    assert(serializedAddressesLen >= 0, 'lookup table is invalid');
+    assert(serializedAddressesLen % 32 === 0, 'lookup table is invalid');
+
+    const numSerializedAddresses = serializedAddressesLen / 32;
+    const {addresses} = BufferLayout.struct<{addresses: Array<Uint8Array>}>([
+      BufferLayout.seq(Layout.publicKey(), numSerializedAddresses, 'addresses'),
+    ]).decode(accountData.slice(LOOKUP_TABLE_META_SIZE));
+
+    return {
+      deactivationSlot: meta.deactivationSlot,
+      lastExtendedSlot: meta.lastExtendedSlot,
+      lastExtendedSlotStartIndex: meta.lastExtendedStartIndex,
+      authority:
+        meta.authority.length !== 0
+          ? new PublicKey(meta.authority[0])
+          : undefined,
+      addresses: addresses.map(address => new PublicKey(address)),
+    };
+  }
+}
+
+const LookupTableMetaLayout = {
+  index: 1,
+  layout: BufferLayout.struct<{
+    typeIndex: number;
+    deactivationSlot: bigint;
+    lastExtendedSlot: number;
+    lastExtendedStartIndex: number;
+    authority: Array<Uint8Array>;
+  }>([
+    BufferLayout.u32('typeIndex'),
+    u64('deactivationSlot'),
+    BufferLayout.nu64('lastExtendedSlot'),
+    BufferLayout.u8('lastExtendedStartIndex'),
+    BufferLayout.u8(), // option
+    BufferLayout.seq(
+      Layout.publicKey(),
+      BufferLayout.offset(BufferLayout.u8(), -1),
+      'authority',
+    ),
+  ]),
+};

web3.js/test/connection.test.ts

@@ -18,6 +18,7 @@ import {
   sendAndConfirmTransaction,
   Keypair,
   Message,
+  AddressLookupTableProgram,
 } from '../src';
 import invariant from '../src/utils/assert';
 import {MOCK_PORT, url} from './url';
@@ -4243,5 +4244,57 @@ describe('Connection', function () {
       const version = await connection.getVersion();
       expect(version['solana-core']).to.be.ok;
     }).timeout(20 * 1000);
+
+    it('getAddressLookupTable', async () => {
+      const payer = Keypair.generate();
+
+      await helpers.airdrop({
+        connection,
+        address: payer.publicKey,
+        amount: LAMPORTS_PER_SOL,
+      });
+
+      const lookupTableAddresses = new Array(10)
+        .fill(0)
+        .map(() => Keypair.generate().publicKey);
+
+      const recentSlot = await connection.getSlot('finalized');
+      const [createIx, lookupTableKey] =
+        AddressLookupTableProgram.createLookupTable({
+          recentSlot,
+          payer: payer.publicKey,
+          authority: payer.publicKey,
+        });
+
+      const transaction = new Transaction().add(createIx).add(
+        AddressLookupTableProgram.extendLookupTable({
+          lookupTable: lookupTableKey,
+          addresses: lookupTableAddresses,
+          authority: payer.publicKey,
+          payer: payer.publicKey,
+        }),
+      );
+      await helpers.processTransaction({
+        connection,
+        transaction,
+        signers: [payer],
+        commitment: 'processed',
+      });
+
+      const lookupTableResponse = await connection.getAddressLookupTable(
+        lookupTableKey,
+        {
+          commitment: 'processed',
+        },
+      );
+      const lookupTableAccount = lookupTableResponse.value;
+      if (!lookupTableAccount) {
+        expect(lookupTableAccount).to.be.ok;
+        return;
+      }
+      expect(lookupTableAccount.isActive()).to.be.true;
+      expect(lookupTableAccount.state.authority).to.eql(payer.publicKey);
+      expect(lookupTableAccount.state.addresses).to.eql(lookupTableAddresses);
+    });
   }
 });