Fix reestablish flow in state channels

src/channel/Base.ts

@@ -1,7 +1,7 @@
 import EventEmitter from 'events';
 import { w3cwebsocket as W3CWebSocket } from 'websocket';
 import { snakeToPascal } from '../utils/string';
-import { buildTx, unpackTx } from '../tx/builder';
+import { unpackTx } from '../tx/builder';
 import { Tag } from '../tx/builder/constants';
 import * as handlers from './handlers';
 import {
@@ -20,7 +20,7 @@ import {
   ChannelMessage,
   ChannelEvents,
 } from './internal';
-import { ChannelError } from '../utils/errors';
+import { ChannelError, IllegalArgumentError } from '../utils/errors';
 import { Encoded } from '../utils/encoder';
 import { TxUnpacked } from '../tx/builder/schema.generated';
 import { EntryTag } from '../tx/builder/entry/constants';
@@ -108,9 +108,16 @@ export default class Channel {
   }
 
   static async _initialize<T extends Channel>(channel: T, options: ChannelOptions): Promise<T> {
+    const reconnect = (options.existingFsmId ?? options.existingChannelId) != null;
+    if (reconnect && (options.existingFsmId == null || options.existingChannelId == null)) {
+      throw new IllegalArgumentError('`existingChannelId`, `existingFsmId` should be both provided or missed');
+    }
+    const reconnectHandler = handlers[
+      options.reestablish === true ? 'awaitingReestablish' : 'awaitingReconnection'
+    ];
     await initialize(
       channel,
-      options.existingFsmId != null ? handlers.awaitingReconnection : handlers.awaitingConnection,
+      reconnect ? reconnectHandler : handlers.awaitingConnection,
       handlers.channelOpen,
       options,
     );
@@ -249,8 +256,7 @@ export default class Channel {
    * signed state and then terminates.
    *
    * The channel can be reestablished by instantiating another Channel instance
-   * with two extra params: existingChannelId and offchainTx (returned from leave
-   * method as channelId and signedTx respectively).
+   * with two extra params: existingChannelId and existingFsmId.
    *
    * @example
    * ```js
@@ -290,16 +296,4 @@ export default class Channel {
       };
     });
   }
-
-  static async reconnect(options: ChannelOptions, txParams: any): Promise<Channel> {
-    const { sign } = options;
-
-    return Channel.initialize({
-      ...options,
-      reconnectTx: await sign(
-        'reconnect',
-        buildTx({ ...txParams, tag: Tag.ChannelClientReconnectTx }),
-      ),
-    });
-  }
 }

src/channel/handlers.ts

@@ -143,18 +143,40 @@ export function awaitingConnection(
   }
 }
 
+export async function awaitingReestablish(
+  channel: Channel,
+  message: ChannelMessage,
+  state: ChannelState,
+): Promise<ChannelFsm> {
+  if (message.method === 'channels.info' && message.params.data.event === 'fsm_up') {
+    channel._fsmId = message.params.data.fsm_id;
+    return {
+      handler: function awaitingChannelReestablished(
+        _: Channel,
+        message2: ChannelMessage,
+        state2: ChannelState,
+      ): ChannelFsm | undefined {
+        if (
+          message2.method === 'channels.info'
+          && message2.params.data.event === 'channel_reestablished'
+        ) return { handler: awaitingOpenConfirmation };
+        return handleUnexpectedMessage(channel, message2, state2);
+      },
+    };
+  }
+  return handleUnexpectedMessage(channel, message, state);
+}
+
 export async function awaitingReconnection(
   channel: Channel,
   message: ChannelMessage,
   state: ChannelState,
 ): Promise<ChannelFsm> {
-  if (message.method === 'channels.info') {
-    if (message.params.data.event === 'fsm_up') {
-      channel._fsmId = message.params.data.fsm_id;
-      const { signedTx } = await channel.state();
-      changeState(channel, signedTx == null ? '' : buildTx(signedTx));
-      return { handler: channelOpen };
-    }
+  if (message.method === 'channels.info' && message.params.data.event === 'fsm_up') {
+    channel._fsmId = message.params.data.fsm_id;
+    const { signedTx } = await channel.state();
+    changeState(channel, signedTx == null ? '' : buildTx(signedTx));
+    return { handler: channelOpen };
   }
   return handleUnexpectedMessage(channel, message, state);
 }
@@ -220,18 +242,25 @@ export function awaitingOnChainTx(
 function awaitingOpenConfirmation(
   channel: Channel,
   message: ChannelMessage,
+  state: ChannelState,
 ): ChannelFsm | undefined {
   if (message.method === 'channels.info' && message.params.data.event === 'open') {
     channel._channelId = message.params.channel_id;
     return {
-      handler(_: Channel, message2: ChannelMessage): ChannelFsm | undefined {
+      handler: function awaitingChannelsUpdate(
+        _: Channel,
+        message2: ChannelMessage,
+        state2: ChannelState,
+      ): ChannelFsm | undefined {
         if (message2.method === 'channels.update') {
           changeState(channel, message2.params.data.state);
           return { handler: channelOpen };
         }
+        return handleUnexpectedMessage(channel, message2, state2);
       },
     };
   }
+  return handleUnexpectedMessage(channel, message, state);
 }
 
 export async function channelOpen(

src/channel/internal.ts

@@ -14,7 +14,6 @@ import {
   ChannelError,
 } from '../utils/errors';
 import { encodeContractAddress } from '../utils/crypto';
-import { buildTx } from '../tx/builder';
 import { ensureError } from '../utils/other';
 
 export interface ChannelEvents {
@@ -53,7 +52,6 @@ export type SignTx = (tx: Encoded.Transaction, options?: SignOptions) => (
  * @see {@link https://github.com/aeternity/protocol/blob/6734de2e4c7cce7e5e626caa8305fb535785131d/node/api/channels_api_usage.md#channel-establishing-parameters}
  */
 interface CommonChannelOptions {
-  existingFsmId?: Encoded.Bytearray;
   /**
    * Channel url (for example: "ws://localhost:3001")
    */
@@ -118,10 +116,14 @@ interface CommonChannelOptions {
    */
   existingChannelId?: Encoded.Channel;
   /**
-   * Offchain transaction (required if reestablishing a channel)
+   * Existing FSM id (required if reestablishing a channel)
+   */
+  existingFsmId?: Encoded.Bytearray;
+  /**
+   * Needs to be provided if reconnecting with calling `leave` before
    */
-  offChainTx?: Encoded.Transaction;
-  reconnectTx?: Encoded.Transaction;
+  // TODO: remove after solving https://github.com/aeternity/aeternity/issues/4399
+  reestablish?: boolean;
   /**
    * The time waiting for a new event to be initiated (default: 600000)
    */
@@ -174,7 +176,6 @@ interface CommonChannelOptions {
    * Function which verifies and signs transactions
    */
   sign: SignTxWithTag;
-  offchainTx?: Encoded.Transaction;
 }
 
 export type ChannelOptions = CommonChannelOptions & ({
@@ -439,16 +440,7 @@ export async function initialize(
       onopen: async (event: Event) => {
         resolve();
         changeStatus(channel, 'connected', event);
-        if (channelOptions.reconnectTx != null) {
-          enterState(channel, { handler: openHandler });
-          const { signedTx } = await channel.state();
-          if (signedTx == null) {
-            throw new ChannelError('`signedTx` missed in state while reconnection');
-          }
-          changeState(channel, buildTx(signedTx));
-        } else {
-          enterState(channel, { handler: connectionHandler });
-        }
+        enterState(channel, { handler: connectionHandler });
         ping(channel);
       },
       onclose: (event: ICloseEvent) => {

src/tx/builder/constants.ts

@@ -105,7 +105,6 @@ export enum Tag {
   ContractCreateTx = 42,
   ContractCallTx = 43,
   ChannelCreateTx = 50,
-  // ChannelSetDelegatesTx = 501,
   ChannelDepositTx = 51,
   ChannelWithdrawTx = 52,
   ChannelForceProgressTx = 521,
@@ -114,7 +113,6 @@ export enum Tag {
   ChannelSlashTx = 55,
   ChannelSettleTx = 56,
   ChannelOffChainTx = 57,
-  ChannelClientReconnectTx = 575,
   ChannelSnapshotSoloTx = 59,
   GaAttachTx = 80,
   GaMetaTx = 81,

src/tx/builder/schema.ts

@@ -349,13 +349,6 @@ export const txSchema = [{
   ttl,
   fee,
   nonce: nonce('fromId'),
-}, {
-  tag: shortUIntConst(Tag.ChannelClientReconnectTx),
-  version: shortUIntConst(1, true),
-  channelId: address(Encoding.Channel),
-  round: shortUInt,
-  role: string,
-  pubkey: address(Encoding.AccountAddress),
 }, {
   tag: shortUIntConst(Tag.GaAttachTx),
   version: shortUIntConst(1, true),

test/integration/channel-other.ts

@@ -75,7 +75,7 @@ describe('Channel other', () => {
     const [initiatorBalanceBeforeClose, responderBalanceBeforeClose] = await getBalances();
     const closeSoloTx = await aeSdk.buildTx({
       tag: Tag.ChannelCloseSoloTx,
-      channelId: await initiatorCh.id(),
+      channelId: initiatorCh.id(),
       fromId: initiator.address,
       poi,
       payload: signedTx,
@@ -85,7 +85,7 @@ describe('Channel other', () => {
 
     const settleTx = await aeSdk.buildTx({
       tag: Tag.ChannelSettleTx,
-      channelId: await initiatorCh.id(),
+      channelId: initiatorCh.id(),
       fromId: initiator.address,
       initiatorAmountFinal: balances[initiator.address],
       responderAmountFinal: balances[responder.address],
@@ -164,36 +164,33 @@ describe('Channel other', () => {
       .should.be.equal(true);
   }).timeout(timeoutBlock);
 
-  // https://github.com/aeternity/protocol/blob/d634e7a3f3110657900759b183d0734e61e5803a/node/api/channels_api_usage.md#reestablish
-  it('can reconnect', async () => {
-    expect(await initiatorCh.round()).to.be.equal(1);
-    const result = await initiatorCh.update(
-      initiator.address,
-      responder.address,
-      100,
-      initiatorSign,
-    );
-    expect(result.accepted).to.equal(true);
-    const channelId = await initiatorCh.id();
+  it('can reconnect a channel without leave', async () => {
+    expect(initiatorCh.round()).to.be.equal(1);
+    await initiatorCh.update(initiator.address, responder.address, 100, initiatorSign);
+    expect(initiatorCh.round()).to.be.equal(2);
+    const channelId = initiatorCh.id();
     const fsmId = initiatorCh.fsmId();
     initiatorCh.disconnect();
+    await waitForChannel(initiatorCh, ['disconnected']);
     const ch = await Channel.initialize({
       ...sharedParams,
       ...initiatorParams,
       existingChannelId: channelId,
       existingFsmId: fsmId,
     });
-    await waitForChannel(ch);
+    await waitForChannel(ch, ['open']);
     expect(ch.fsmId()).to.be.equal(fsmId);
-    expect(await ch.round()).to.be.equal(2);
+    expect(ch.round()).to.be.equal(2);
     const state = await ch.state();
-    ch.disconnect();
     assertNotNull(state.signedTx);
     expect(state.signedTx.encodedTx.tag).to.be.equal(Tag.ChannelOffChainTx);
+    await ch.update(initiator.address, responder.address, 100, initiatorSign);
+    expect(ch.round()).to.be.equal(3);
+    ch.disconnect();
   });
 
   it('can post backchannel update', async () => {
-    expect(await responderCh.round()).to.be.equal(1);
+    expect(responderCh.round()).to.be.equal(1);
     initiatorCh.disconnect();
     const { accepted } = await responderCh.update(
       initiator.address,
@@ -202,7 +199,7 @@ describe('Channel other', () => {
       responderSign,
     );
     expect(accepted).to.equal(false);
-    expect(await responderCh.round()).to.be.equal(1);
+    expect(responderCh.round()).to.be.equal(1);
     const result = await responderCh.update(
       initiator.address,
       responder.address,
@@ -212,7 +209,7 @@ describe('Channel other', () => {
       ),
     );
     result.accepted.should.equal(true);
-    expect(await responderCh.round()).to.be.equal(2);
+    expect(responderCh.round()).to.be.equal(2);
     expect(result.signedTx).to.be.a('string');
   });
 });

test/integration/channel-utils.ts

@@ -4,19 +4,19 @@ import {
 } from '../../src';
 import { ChannelOptions, SignTxWithTag } from '../../src/channel/internal';
 
-export async function waitForChannel(channel: Channel): Promise<void> {
+export async function waitForChannel(channel: Channel, statuses: string[]): Promise<void> {
   return new Promise((resolve, reject) => {
-    channel.on('statusChanged', (status: string) => {
-      switch (status) {
-        case 'open':
-          resolve();
-          break;
-        case 'disconnected':
-          reject(new Error('Unexpected SC status: disconnected'));
-          break;
-        default:
+    function handler(status: string): void {
+      const expectedStatus = statuses.shift();
+      if (status !== expectedStatus) {
+        reject(new Error(`Expected SC status ${expectedStatus}, got ${status} instead`));
+        channel.off('statusChanged', handler);
+      } else if (statuses.length === 0) {
+        resolve();
+        channel.off('statusChanged', handler);
       }
-    });
+    }
+    channel.on('statusChanged', handler);
   });
 }
 
@@ -46,7 +46,10 @@ export async function initializeChannels(
     ...sharedParams,
     ...responderParams,
   });
-  await Promise.all([waitForChannel(initiatorCh), waitForChannel(responderCh)]);
+  await Promise.all([
+    waitForChannel(initiatorCh, ['accepted', 'signed', 'open']),
+    waitForChannel(responderCh, ['halfSigned', 'open']),
+  ]);
   return [initiatorCh, responderCh];
 }
 

test/integration/channel.ts

@@ -572,33 +572,32 @@ describe('Channel', () => {
     // TODO: check `initiatorAmountFinal` and `responderAmountFinal`
   });
 
-  let existingChannelId: Encoded.Channel;
-  let offchainTx: Encoded.Transaction;
   it('can leave a channel', async () => {
     initiatorCh.disconnect();
     responderCh.disconnect();
     [initiatorCh, responderCh] = await initializeChannels(initiatorParams, responderParams);
-    initiatorCh.round(); // existingChannelRound
+    await initiatorCh.update(initiator.address, responder.address, 100, initiatorSign);
     const result = await initiatorCh.leave();
     expect(result.channelId).to.satisfy((t: string) => t.startsWith('ch_'));
     expect(result.signedTx).to.satisfy((t: string) => t.startsWith('tx_'));
-    existingChannelId = result.channelId;
-    offchainTx = result.signedTx;
   });
 
+  // https://github.com/aeternity/protocol/blob/d634e7a3f3110657900759b183d0734e61e5803a/node/api/channels_api_usage.md#reestablish
   it('can reestablish a channel', async () => {
+    expect(initiatorCh.round()).to.be.equal(2);
     initiatorCh = await Channel.initialize({
       ...sharedParams,
       ...initiatorParams,
-      // @ts-expect-error TODO: use existingChannelId instead existingFsmId
-      existingFsmId: existingChannelId,
-      offchainTx,
+      reestablish: true,
+      existingChannelId: initiatorCh.id(),
+      existingFsmId: initiatorCh.fsmId(),
     });
-    await waitForChannel(initiatorCh);
-    // TODO: why node doesn't return signed_tx when channel is reestablished?
-    // initiatorCh.round().should.equal(existingChannelRound)
+    await waitForChannel(initiatorCh, ['open']);
+    expect(initiatorCh.round()).to.be.equal(2);
     sinon.assert.notCalled(initiatorSignTag);
     sinon.assert.notCalled(responderSignTag);
+    await initiatorCh.update(initiator.address, responder.address, 100, initiatorSign);
+    expect(initiatorCh.round()).to.be.equal(3);
   });
 
   describe('throws errors', () => {