chore(release): 0.1.0-develop.26 [skip ci]

# [0.1.0-develop.26](https://git.lumeweb.com/LumeWeb/libethsync/compare/v0.1.0-develop.25...v0.1.0-develop.26) (2023-07-12)

CHANGELOG.md

@@ -1,3 +1,5 @@
+# [0.1.0-develop.26](https://git.lumeweb.com/LumeWeb/libethsync/compare/v0.1.0-develop.25...v0.1.0-develop.26) (2023-07-12)
+
 # [0.1.0-develop.25](https://git.lumeweb.com/LumeWeb/libethsync/compare/v0.1.0-develop.24...v0.1.0-develop.25) (2023-07-12)
 
 # [0.1.0-develop.24](https://git.lumeweb.com/LumeWeb/libethsync/compare/v0.1.0-develop.23...v0.1.0-develop.24) (2023-07-11)

npm-shrinkwrap.json

@@ -1,12 +1,12 @@
 {
     "name": "@lumeweb/libethclient",
-    "version": "0.1.0-develop.25",
+    "version": "0.1.0-develop.26",
     "lockfileVersion": 3,
     "requires": true,
     "packages": {
         "": {
             "name": "@lumeweb/libethclient",
-            "version": "0.1.0-develop.25",
+            "version": "0.1.0-develop.26",
             "dependencies": {
                 "@chainsafe/as-sha256": "^0.3.1",
                 "@chainsafe/bls": "7.1.1",

package.json

@@ -1,6 +1,6 @@
 {
     "name": "@lumeweb/libethsync",
-    "version": "0.1.0-develop.25",
+    "version": "0.1.0-develop.26",
     "type": "module",
     "repository": {
         "type": "git",

src/baseClient.ts

@@ -6,14 +6,16 @@ import {
 } from "@lodestar/light-client/utils";
 import { init } from "@chainsafe/bls/switchable";
 import { Mutex } from "async-mutex";
-import { fromHexString } from "@chainsafe/ssz";
+import { fromHexString, toHexString } from "@chainsafe/ssz";
-import { getDefaultClientConfig } from "#util.js";
+import { deserializePubkeys, getDefaultClientConfig } from "#util.js";
-
+import { capella, LightClientUpdate } from "#types.js";
-import isNode from "detect-node";
+import { deserializeSyncCommittee } from "@lodestar/light-client/utils/index.js";
+import bls from "@chainsafe/bls/switchable.js";
+import { assertValidLightClientUpdate } from "@lodestar/light-client/validation.js";
 
 export interface BaseClientOptions {
   prover: IProver;
-  store?: IStore;
+  store: IStore;
 }
 
 export default abstract class BaseClient {
@@ -24,10 +26,10 @@ export default abstract class BaseClient {
     (pk) => fromHexString(pk),
   );
   protected genesisPeriod = computeSyncPeriodAtSlot(this.config.genesis.slot);
-  private genesisTime = this.config.genesis.time;
   protected booted = false;
-  private syncMutex = new Mutex();
   protected options: BaseClientOptions;
+  private genesisTime = this.config.genesis.time;
+  private syncMutex = new Mutex();
 
   constructor(options: BaseClientOptions) {
     this.options = options;
@@ -43,6 +45,10 @@ export default abstract class BaseClient {
     return this._latestPeriod === this.getCurrentPeriod();
   }
 
+  public get store(): IStore {
+    return this.options.store as IStore;
+  }
+
   public async sync(): Promise<void> {
     await init("herumi");
 
@@ -88,7 +94,6 @@ export default abstract class BaseClient {
   protected async subscribe(callback?: (ei: ExecutionInfo) => void) {
     setInterval(async () => {
       try {
-        await this._sync();
         const ei = await this.getLatestExecution();
         if (ei && ei.blockHash !== this.latestBlockHash) {
           this.latestBlockHash = ei.blockHash;
@@ -100,16 +105,128 @@ export default abstract class BaseClient {
     }, POLLING_DELAY);
   }
 
-  public get store(): IStore {
+  protected async getLatestExecution(): Promise<ExecutionInfo | null> {
-    return this.options.store as IStore;
+    await this._sync();
+    const update = capella.ssz.LightClientUpdate.deserialize(
+      this.store.getUpdate(this.latestPeriod),
+    );
+
+    return {
+      blockHash: toHexString(update.attestedHeader.execution.blockHash),
+      blockNumber: update.attestedHeader.execution.blockNumber,
+    };
+  }
+  async syncProver(
+    startPeriod: number,
+    currentPeriod: number,
+    startCommittee: Uint8Array[],
+  ): Promise<{ syncCommittee: Uint8Array[]; period: number }> {
+    for (let period = startPeriod; period < currentPeriod; period += 1) {
+      try {
+        const updates = await this.options.prover.getSyncUpdate(
+          period,
+          currentPeriod,
+        );
+
+        for (let i = 0; i < updates.length; i++) {
+          const curPeriod = period + i;
+          const update = updates[i];
+
+          const validOrCommittee = await this.syncUpdateVerifyGetCommittee(
+            startCommittee,
+            curPeriod,
+            update,
+          );
+
+          if (!(validOrCommittee as boolean)) {
+            console.log(`Found invalid update at period(${curPeriod})`);
+            return {
+              syncCommittee: startCommittee,
+              period: curPeriod,
+            };
           }
 
-  // committee and prover index of the first honest prover
+          await this.options.store.addUpdate(period, update);
-  protected abstract syncFromGenesis(): Promise<Uint8Array[]>;
 
-  protected abstract syncFromLastUpdate(
+          startCommittee = validOrCommittee as Uint8Array[];
-    startPeriod?: number,
+          period = curPeriod;
-  ): Promise<Uint8Array[]>;
+        }
+      } catch (e) {
+        console.error(`failed to fetch sync update for period(${period})`);
+        return {
+          syncCommittee: startCommittee,
+          period,
+        };
+      }
+    }
+    return {
+      syncCommittee: startCommittee,
+      period: currentPeriod,
+    };
+  }
 
-  protected abstract getLatestExecution(): Promise<ExecutionInfo | null>;
+  protected async syncUpdateVerifyGetCommittee(
+    prevCommittee: Uint8Array[],
+    period: number,
+    update: LightClientUpdate,
+  ): Promise<false | Uint8Array[]> {
+    const updatePeriod = computeSyncPeriodAtSlot(
+      update.attestedHeader.beacon.slot,
+    );
+    if (period !== updatePeriod) {
+      console.error(
+        `Expected update with period ${period}, but received ${updatePeriod}`,
+      );
+      return false;
+    }
+
+    const prevCommitteeFast = deserializeSyncCommittee({
+      pubkeys: prevCommittee,
+      aggregatePubkey: bls.PublicKey.aggregate(
+        deserializePubkeys(prevCommittee),
+      ).toBytes(),
+    });
+
+    try {
+      // check if the update has valid signatures
+      await assertValidLightClientUpdate(
+        this.config.chainConfig,
+        prevCommitteeFast,
+        update,
+      );
+      return update.nextSyncCommittee.pubkeys;
+    } catch (e) {
+      console.error(e);
+      return false;
+    }
+  }
+
+  protected async syncFromGenesis(): Promise<Uint8Array[]> {
+    return this.syncFromLastUpdate(this.genesisPeriod);
+  }
+
+  protected async syncFromLastUpdate(
+    startPeriod = this.latestPeriod,
+  ): Promise<Uint8Array[]> {
+    const currentPeriod = this.getCurrentPeriod();
+    let startCommittee = this.genesisCommittee;
+    console.debug(
+      `Sync started from period(${startPeriod}) to period(${currentPeriod})`,
+    );
+
+    const { syncCommittee, period } = await this.syncProver(
+      startPeriod,
+      currentPeriod,
+      startCommittee,
+    );
+    if (period === currentPeriod) {
+      console.debug(
+        `Sync completed from period(${startPeriod}) to period(${currentPeriod})`,
+      );
+
+      return syncCommittee;
+    }
+
+    throw new Error("no honest prover found");
+  }
 }

src/client/client.ts

@@ -1,17 +1,9 @@
 import BaseClient, { BaseClientOptions } from "#baseClient.js";
-import { ExecutionInfo, IVerifyingProviderConstructor } from "#interfaces.js";
+import { IProver, IVerifyingProviderConstructor } from "#interfaces.js";
-import { DEFAULT_BATCH_SIZE } from "#constants.js";
-import { IClientProver } from "#client/prover.js";
-import {
-  getCommitteeHash,
-  optimisticUpdateFromJSON,
-  optimisticUpdateVerify,
-} from "#util.js";
-import { equalBytes } from "@noble/curves/abstract/utils";
 import { IClientVerifyingProvider } from "#client/verifyingProvider.js";
 
 interface Config extends BaseClientOptions {
-  prover: IClientProver;
+  prover: IProver;
   provider: IVerifyingProviderConstructor<IClientVerifyingProvider>;
   rpcHandler: Function;
 }
@@ -48,74 +40,6 @@ export default class Client extends BaseClient {
     }
   }
 
-  protected async getLatestExecution(): Promise<ExecutionInfo | null> {
-    const updateJSON = await this.options.prover.callback(
-      "consensus_optimistic_update",
-    );
-    const update = optimisticUpdateFromJSON(updateJSON);
-    const verify = await optimisticUpdateVerify(
-      this.latestCommittee as Uint8Array[],
-      update,
-    );
-    if (!verify.correct) {
-      console.error(`Invalid Optimistic Update: ${verify.reason}`);
-      return null;
-    }
-    console.log(
-      `Optimistic update verified for slot ${updateJSON.attested_header.beacon.slot}`,
-    );
-    return {
-      blockHash: updateJSON.attested_header.execution.block_hash,
-      blockNumber: updateJSON.attested_header.execution.block_number,
-    };
-  }
-
-  protected syncFromGenesis(): Promise<Uint8Array[]> {
-    return this.syncFromLastUpdate(0);
-  }
-
-  protected async syncFromLastUpdate(
-    startPeriod = this.latestPeriod,
-  ): Promise<Uint8Array[]> {
-    const currentPeriod = this.getCurrentPeriod();
-
-    let lastCommitteeHash: Uint8Array = getCommitteeHash(this.genesisCommittee);
-
-    for (let period = startPeriod + 1; period <= currentPeriod; period++) {
-      try {
-        lastCommitteeHash = await this.options.prover.getCommitteeHash(
-          period,
-          currentPeriod,
-          DEFAULT_BATCH_SIZE,
-        );
-      } catch (e: any) {
-        throw new Error(
-          `failed to fetch committee hash for prover at period(${period}): ${e.meessage}`,
-        );
-      }
-    }
-    return this.getCommittee(currentPeriod, lastCommitteeHash);
-  }
-
-  private async getCommittee(
-    period: number,
-    expectedCommitteeHash: Uint8Array | null,
-  ): Promise<Uint8Array[]> {
-    if (period === this.genesisPeriod) {
-      return this.genesisCommittee;
-    }
-    if (!expectedCommitteeHash) {
-      throw new Error("expectedCommitteeHash required");
-    }
-    const committee = await this.options.prover.getCommittee(period);
-    const committeeHash = getCommitteeHash(committee);
-    if (!equalBytes(committeeHash, expectedCommitteeHash as Uint8Array)) {
-      throw new Error("prover responded with an incorrect committee");
-    }
-
-    return committee;
-  }
-
   public async rpcCall(method: string, params: any) {
     return this.provider?.rpcMethod(method, params);
   }

src/client/index.ts

@@ -1,6 +1,7 @@
 import Client from "./client.js";
-import Prover, { IClientProver, ProverRequestCallback } from "./prover.js";
+import Prover, { ProverRequestCallback } from "../prover.js";
 import VerifyingProvider from "./verifyingProvider.js";
+import Store from "#store.js";
 
 function createDefaultClient(
   proverHandler: ProverRequestCallback,
@@ -8,6 +9,7 @@ function createDefaultClient(
 ): Client {
   return new Client({
     prover: new Prover(proverHandler),
+    store: new Store(60 * 60),
     provider: VerifyingProvider,
     rpcHandler,
   });
@@ -15,5 +17,5 @@ function createDefaultClient(
 
 export { RPCRequest, RPCRequestRaw, RPCResponse } from "./rpc.js";
 export { Client, Prover, VerifyingProvider, createDefaultClient };
-export { IClientProver, ProverRequestCallback };
+export { ProverRequestCallback };
 export * from "#interfaces.js";

src/client/prover.ts

@@ -1,73 +0,0 @@
-import {
-  ConsensusCommitteeHashesRequest,
-  ConsensusCommitteePeriodRequest,
-  IProver,
-} from "#interfaces.js";
-import { CommitteeSSZ, HashesSSZ } from "#ssz.js";
-import { LightClientUpdate } from "#types.js";
-import * as capella from "@lodestar/types/capella";
-
-export type ProverRequestCallback = (
-  action: string,
-  args?: ConsensusCommitteeHashesRequest | ConsensusCommitteePeriodRequest,
-) => Promise<any>;
-
-export interface IClientProver extends IProver {
-  get callback(): ProverRequestCallback;
-  getCommittee(period: number | "latest"): Promise<Uint8Array[]>;
-  getSyncUpdate(period: number): Promise<LightClientUpdate>;
-  getCommitteeHash(
-    period: number,
-    currentPeriod: number,
-    cacheCount: number,
-  ): Promise<Uint8Array>;
-}
-
-export default class Prover implements IClientProver {
-  cachedHashes: Map<number, Uint8Array> = new Map();
-
-  constructor(callback: ProverRequestCallback) {
-    this._callback = callback;
-  }
-
-  private _callback: ProverRequestCallback;
-
-  get callback(): ProverRequestCallback {
-    return this._callback;
-  }
-
-  async getCommittee(period: number | "latest"): Promise<Uint8Array[]> {
-    const res = await this.callback("consensus_committee_period", { period });
-    return CommitteeSSZ.deserialize(Uint8Array.from(Object.values(res)));
-  }
-
-  async getSyncUpdate(period: number): Promise<LightClientUpdate> {
-    const res = await this.callback("consensus_committee_period", { period });
-    return capella.ssz.LightClientUpdate.deserialize(
-      Uint8Array.from(Object.values(res)),
-    );
-  }
-
-  async _getHashes(startPeriod: number, count: number): Promise<Uint8Array[]> {
-    const res = await this.callback("consensus_committee_hashes", {
-      start: startPeriod,
-      count,
-    });
-    return HashesSSZ.deserialize(Uint8Array.from(Object.values(res)));
-  }
-
-  async getCommitteeHash(
-    period: number,
-    currentPeriod: number,
-    cacheCount: number,
-  ): Promise<Uint8Array> {
-    const _count = Math.min(currentPeriod - period + 1, cacheCount);
-    if (!this.cachedHashes.has(period)) {
-      const vals = await this._getHashes(period, _count);
-      for (let i = 0; i < _count; i++) {
-        this.cachedHashes.set(period + i, vals[i]);
-      }
-    }
-    return this.cachedHashes.get(period)!;
-  }
-}

src/interfaces.ts

@@ -1,24 +1,21 @@
 import { BeaconConfig } from "@lodestar/config";
 import { GenesisData, LightClientUpdate } from "#types.js";
-
+import { ProverRequestCallback } from "#client/index.js";
-import Provider from "#client/verifyingProvider.js";
+import BaseClient from "#baseClient.js";
 
 export interface IProver {
+  get callback(): ProverRequestCallback;
+  set client(value: BaseClient);
   getSyncUpdate(
+    startPeriod: number,
     period: number,
-    currentPeriod: number,
+  ): Promise<LightClientUpdate[]>;
-    cacheCount: number,
-  ): Promise<LightClientUpdate>;
 }
 
 export interface IStore {
-  addUpdate(period: number, update: LightClientUpdate): Promise<void>;
+  addUpdate(period: number, update: LightClientUpdate): void;
-
   getUpdate(period: number): Uint8Array;
-
+  hasUpdate(period: number): boolean;
-  getCommittee(period: number): Uint8Array;
-
-  getCommitteeHashes(period: number, count: number): Uint8Array;
 }
 
 export interface IVerifyingProvider {
@@ -41,15 +38,7 @@ export interface ExecutionInfo {
   blockNumber: number;
 }
 
-export interface ConsensusCommitteeHashesRequest {
+export interface ConsensusCommitteeUpdateRequest {
   start: number;
   count: number;
 }
-
-export interface ConsensusCommitteePeriodRequest {
-  period: number | "latest";
-}
-
-export interface ConsensusBlockRequest {
-  block: number;
-}

src/node/client.ts

@@ -42,144 +42,9 @@ export default class Client extends BaseClient {
     this.http.defaults.baseURL = this.beaconUrl;
   }
 
-  private _latestOptimisticUpdate: any;
-
-  get latestOptimisticUpdate(): any {
-    return this._latestOptimisticUpdate;
-  }
-
   async sync(): Promise<void> {
     await super.sync();
 
     this.subscribe();
   }
-
-  async syncProver(
-    startPeriod: number,
-    currentPeriod: number,
-    startCommittee: Uint8Array[],
-  ): Promise<{ syncCommittee: Uint8Array[]; period: number }> {
-    for (let period = startPeriod; period < currentPeriod; period += 1) {
-      try {
-        const update = await this.options.prover.getSyncUpdate(
-          period,
-          currentPeriod,
-          DEFAULT_BATCH_SIZE,
-        );
-        const validOrCommittee = await this.syncUpdateVerifyGetCommittee(
-          startCommittee,
-          period,
-          update,
-        );
-
-        if (!(validOrCommittee as boolean)) {
-          console.log(`Found invalid update at period(${period})`);
-          return {
-            syncCommittee: startCommittee,
-            period,
-          };
-        }
-
-        await this.options.store?.addUpdate(period, update);
-        startCommittee = validOrCommittee as Uint8Array[];
-      } catch (e) {
-        console.error(`failed to fetch sync update for period(${period})`);
-        return {
-          syncCommittee: startCommittee,
-          period,
-        };
-      }
-    }
-    return {
-      syncCommittee: startCommittee,
-      period: currentPeriod,
-    };
-  }
-
-  protected async getLatestExecution(): Promise<ExecutionInfo | null> {
-    const updateJSON = await getConsensusOptimisticUpdate();
-    const update = optimisticUpdateFromJSON(updateJSON);
-    const verify = await optimisticUpdateVerify(
-      this.latestCommittee as Uint8Array[],
-      update,
-    );
-
-    if (!verify.correct) {
-      // @ts-ignore
-      console.error(`Invalid Optimistic Update: ${verify?.reason}`);
-      return null;
-    }
-
-    this._latestOptimisticUpdate = updateJSON;
-
-    return {
-      blockHash: toHexString(update.attestedHeader.execution.blockHash),
-      blockNumber: update.attestedHeader.execution.blockNumber,
-    };
-  }
-
-  protected async syncFromGenesis(): Promise<Uint8Array[]> {
-    return this.syncFromLastUpdate(this.genesisPeriod);
-  }
-
-  protected async syncFromLastUpdate(
-    startPeriod = this.latestPeriod,
-  ): Promise<Uint8Array[]> {
-    const currentPeriod = this.getCurrentPeriod();
-    let startCommittee = this.genesisCommittee;
-    console.debug(
-      `Sync started from period(${startPeriod}) to period(${currentPeriod})`,
-    );
-
-    const { syncCommittee, period } = await this.syncProver(
-      startPeriod,
-      currentPeriod,
-      startCommittee,
-    );
-    if (period === currentPeriod) {
-      console.debug(
-        `Sync completed from period(${startPeriod}) to period(${currentPeriod})`,
-      );
-
-      return syncCommittee;
-    }
-
-    throw new Error("no honest prover found");
-  }
-
-  protected async syncUpdateVerifyGetCommittee(
-    prevCommittee: Uint8Array[],
-    period: number,
-    update: LightClientUpdate,
-  ): Promise<false | Uint8Array[]> {
-    const updatePeriod = computeSyncPeriodAtSlot(
-      update.attestedHeader.beacon.slot,
-    );
-    if (period !== updatePeriod) {
-      console.error(
-        `Expected update with period ${period}, but received ${updatePeriod}`,
-      );
-      return false;
-    }
-
-    const prevCommitteeFast = deserializeSyncCommittee({
-      pubkeys: prevCommittee,
-      aggregatePubkey: bls.PublicKey.aggregate(
-        deserializePubkeys(prevCommittee),
-      ).toBytes(),
-    });
-
-    try {
-      // check if the update has valid signatures
-      await assertValidLightClientUpdate(
-        this.config.chainConfig,
-        prevCommitteeFast,
-        update,
-      );
-      return update.nextSyncCommittee.pubkeys;
-    } catch (e) {
-      console.error(e);
-      return false;
-    }
-  }
 }

src/node/index.ts

@@ -1,11 +1,20 @@
 import Client from "./client.js";
-import Prover from "./prover.js";
+import Store from "../store.js";
-import Store from "./store.js";
+import Prover from "#prover.js";
+import * as capella from "@lodestar/types/capella";
+import { consensusClient } from "#util.js";
 
 function createDefaultClient(beaconUrl: string): Client {
   return new Client({
     store: new Store(),
-    prover: new Prover(),
+    prover: new Prover(async (args) => {
+      const res = await consensusClient.get(
+        `/eth/v1/beacon/light_client/updates?start_period=${args.start}&count=${args.count}`,
+      );
+      return res.data.map((u: any) =>
+        capella.ssz.LightClientUpdate.fromJson(u.data),
+      );
+    }),
     beaconUrl,
   });
 }

src/node/prover.ts

@@ -1,37 +0,0 @@
-import { IProver } from "#interfaces.js";
-import { LightClientUpdate } from "#types.js";
-import { consensusClient } from "#util.js";
-import { AxiosInstance } from "axios";
-import * as capella from "@lodestar/types/capella";
-
-export default class Prover implements IProver {
-  cachedSyncUpdate: Map<number, LightClientUpdate> = new Map();
-  private http: AxiosInstance = consensusClient;
-
-  async _getSyncUpdates(
-    startPeriod: number,
-    maxCount: number,
-  ): Promise<LightClientUpdate[]> {
-    const res = await this.http(
-      `/eth/v1/beacon/light_client/updates?start_period=${startPeriod}&count=${maxCount}`,
-    );
-    return res.data.map((u: any) =>
-      capella.ssz.LightClientUpdate.fromJson(u.data),
-    );
-  }
-
-  async getSyncUpdate(
-    period: number,
-    currentPeriod: number,
-    cacheCount: number,
-  ): Promise<LightClientUpdate> {
-    const _cacheCount = Math.min(currentPeriod - period + 1, cacheCount);
-    if (!this.cachedSyncUpdate.has(period)) {
-      const vals = await this._getSyncUpdates(period, _cacheCount);
-      for (let i = 0; i < _cacheCount; i++) {
-        this.cachedSyncUpdate.set(period + i, vals[i]);
-      }
-    }
-    return this.cachedSyncUpdate.get(period)!;
-  }
-}

src/node/store.ts

@@ -1,57 +0,0 @@
-import { digest } from "@chainsafe/as-sha256";
-import { CommitteeSSZ, HashesSSZ } from "#ssz.js";
-import { IStore } from "#interfaces.js";
-import { concatBytes } from "@noble/hashes/utils";
-import { LightClientUpdate } from "#types.js";
-import * as capella from "@lodestar/types/capella";
-
-export default class Store implements IStore {
-  store: {
-    [period: number]: {
-      update: Uint8Array;
-      nextCommittee: Uint8Array;
-      nextCommitteeHash: Uint8Array;
-    };
-  } = {};
-
-  async addUpdate(period: number, update: LightClientUpdate) {
-    try {
-      this.store[period] = {
-        update: capella.ssz.LightClientUpdate.serialize(update),
-        nextCommittee: CommitteeSSZ.serialize(update.nextSyncCommittee.pubkeys),
-        nextCommitteeHash: digest(
-          concatBytes(...update.nextSyncCommittee.pubkeys),
-        ),
-      };
-    } catch (e) {
-      console.log(e);
-    }
-  }
-
-  getUpdate(period: number): Uint8Array {
-    if (period in this.store) return this.store[period].update;
-    throw new Error(`update unavailable for period ${period}`);
-  }
-
-  getCommittee(period: number): Uint8Array {
-    if (period < 1)
-      throw new Error("committee not unavailable for period less than 1");
-    const predPeriod = period - 1;
-    if (predPeriod in this.store) return this.store[predPeriod].nextCommittee;
-    throw new Error(`committee unavailable for period ${predPeriod}`);
-  }
-
-  getCommitteeHashes(period: number, count: number): Uint8Array {
-    if (period < 1)
-      throw new Error("committee not unavailable for period less than 1");
-    const predPeriod = period - 1;
-
-    const hashes = new Array(count).fill(0).map((_, i) => {
-      const p = predPeriod + i;
-      if (p in this.store) return this.store[p].nextCommitteeHash;
-      throw new Error(`committee unavailable for period ${p}`);
-    });
-
-    return HashesSSZ.serialize(hashes);
-  }
-}

src/prover.ts

@@ -0,0 +1,72 @@
+import { ConsensusCommitteeUpdateRequest, IProver } from "#interfaces.js";
+import { LightClientUpdate } from "#types.js";
+import * as capella from "@lodestar/types/capella";
+import BaseClient from "#baseClient.js";
+
+export type ProverRequestCallback = (
+  args: ConsensusCommitteeUpdateRequest,
+) => Promise<any>;
+
+export default class Prover implements IProver {
+  constructor(callback: ProverRequestCallback) {
+    this._callback = callback;
+  }
+
+  private _client?: BaseClient;
+
+  set client(value: BaseClient) {
+    this._client = value;
+  }
+
+  private _callback: ProverRequestCallback;
+
+  get callback(): ProverRequestCallback {
+    return this._callback;
+  }
+
+  async getSyncUpdate(
+    startPeriod: number,
+    count: number,
+  ): Promise<LightClientUpdate[]> {
+    let end = startPeriod + count;
+    let hasStart = this.client.store.hasUpdate(startPeriod);
+    let hasEnd = this.client.store.hasUpdate(startPeriod + count);
+
+    let trueStart = startPeriod;
+    let trueCount = count;
+
+    if (hasStart && !hasEnd) {
+      for (let i = startPeriod; i <= end; i++) {
+        if (!this.client.store.hasUpdate(i)) {
+          trueStart = i;
+          trueCount = end - i;
+        }
+      }
+    }
+
+    const res = await this.callback({
+      start: trueStart,
+      count: trueCount,
+    });
+
+    const updates: LightClientUpdate[] = [];
+
+    if (trueStart != startPeriod) {
+      for (let i = 0; i < trueStart - startPeriod; i++) {
+        updates.push(
+          capella.ssz.LightClientUpdate.deserialize(
+            this.client.store.getUpdate(startPeriod + i),
+          ),
+        );
+      }
+    }
+
+    for (let i = 0; i < trueCount; i++) {
+      updates.push(
+        capella.ssz.LightClientUpdate.deserialize(res[startPeriod + i]),
+      );
+    }
+
+    return updates;
+  }
+}

src/store.ts

@@ -0,0 +1,45 @@
+import { digest } from "@chainsafe/as-sha256";
+import { CommitteeSSZ, HashesSSZ } from "#ssz.js";
+import { IStore } from "#interfaces.js";
+import { concatBytes } from "@noble/hashes/utils";
+import { LightClientUpdate } from "#types.js";
+import * as capella from "@lodestar/types/capella";
+import NodeCache from "node-cache";
+
+export interface StoreItem {
+  update: Uint8Array;
+  nextCommittee: Uint8Array;
+  nextCommitteeHash: Uint8Array;
+}
+
+export default class Store implements IStore {
+  private store = new NodeCache();
+
+  constructor(expire: number = 0) {
+    this.store.options.stdTTL = 0;
+  }
+
+  addUpdate(period: number, update: LightClientUpdate) {
+    try {
+      this.store.set(period, {
+        update: capella.ssz.LightClientUpdate.serialize(update),
+        nextCommittee: CommitteeSSZ.serialize(update.nextSyncCommittee.pubkeys),
+        nextCommitteeHash: digest(
+          concatBytes(...update.nextSyncCommittee.pubkeys),
+        ),
+      });
+    } catch (e) {
+      console.log(e);
+    }
+  }
+
+  getUpdate(period: number): Uint8Array {
+    if (this.store.has(period)) {
+      return this.store.get<StoreItem>(period)?.update as Uint8Array;
+    }
+    throw new Error(`update unavailable for period ${period}`);
+  }
+  hasUpdate(period: number): boolean {
+    return this.store.has(period);
+  }
+}