*Switch to optimistic approach that uses the relay as a light proxy

package.json

@@ -9,6 +9,7 @@
     "build": "npm run compile && node ./dist-build/build.mjs dev"
   },
   "dependencies": {
+    "@chainsafe/as-sha256": "^0.3.1",
     "@chainsafe/bls": "^7.1.1",
     "@chainsafe/blst": "^0.2.8",
     "@chainsafe/ssz": "^0.10.2",
@@ -32,7 +33,6 @@
     "path-browserify": "^1.0.1",
     "rlp": "^3.0.0",
     "stream-browserify": "^3.0.0",
-    "ts-essentials": "^9.3.1",
     "web3-core": "^1.9.0",
     "web3-core-method": "^1.9.0",
     "web3-eth": "^1.9.0",

src/client/client.ts

@@ -6,7 +6,11 @@ import {
   OptimisticUpdate,
   VerifyWithReason,
 } from "./types.js";
-import { getDefaultClientConfig } from "./utils.js";
+import {
+  concatUint8Array,
+  getDefaultClientConfig,
+  isUint8ArrayEq,
+} from "./utils.js";
 import { IProver } from "./interfaces.js";
 import {
   BEACON_SYNC_SUPER_MAJORITY,
@@ -25,12 +29,12 @@ import { SyncCommitteeFast } from "@lodestar/light-client";
 import bls from "@chainsafe/bls/switchable";
 import { PublicKey } from "@chainsafe/bls/types.js";
 import { fromHexString, toHexString } from "@chainsafe/ssz";
-import { AsyncOrSync } from "ts-essentials";
 import * as altair from "@lodestar/types/altair";
 import * as phase0 from "@lodestar/types/phase0";
 import * as bellatrix from "@lodestar/types/bellatrix";
 import { init } from "@chainsafe/bls/switchable";
 import { VerifyingProvider } from "./rpc/provider.js";
+import { digest } from "@chainsafe/as-sha256";
 
 export default class Client {
   latestCommittee?: Uint8Array[];
@@ -85,55 +89,13 @@ export default class Client {
     return this._provider;
   }
 
-  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.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(${period})`);
-          return {
-            syncCommittee: startCommittee,
-            period,
-          };
-        }
-        startCommittee = validOrCommittee as Uint8Array[];
-      } catch (e) {
-        console.error(`failed to fetch sync update for period(${period})`);
-        return {
-          syncCommittee: startCommittee,
-          period,
-        };
-      }
-    }
-    return {
-      syncCommittee: startCommittee,
-      period: currentPeriod,
-    };
-  }
-
-  // returns the prover info containing the current sync
-
   public getCurrentPeriod(): number {
     return computeSyncPeriodAtSlot(
       getCurrentSlot(this.config.chainConfig, this.genesisTime)
     );
   }
 
-  public async subscribe(callback: (ei: ExecutionInfo) => AsyncOrSync<void>) {
+  public async subscribe(callback: (ei: ExecutionInfo) => void) {
     setInterval(async () => {
       try {
         await this._sync();
@@ -148,10 +110,6 @@ export default class Client {
     }, POLLING_DELAY);
   }
 
-  optimisticUpdateFromJSON(update: any): OptimisticUpdate {
-    return altair.ssz.LightClientOptimisticUpdate.fromJson(update);
-  }
-
   async optimisticUpdateVerify(
     committee: Uint8Array[],
     update: OptimisticUpdate
@@ -195,7 +153,7 @@ export default class Client {
     return this.getNextValidExecutionInfo(retry - 1);
   }
 
-  protected async _sync() {
+  private async _sync() {
     const currentPeriod = this.getCurrentPeriod();
     if (currentPeriod > this.latestPeriod) {
       this.latestCommittee = await this.syncFromGenesis();
@@ -204,59 +162,47 @@ export default class Client {
   }
 
   // committee and prover index of the first honest prover
-  protected async syncFromGenesis(): Promise<Uint8Array[]> {
+  private async syncFromGenesis(): Promise<Uint8Array[]> {
-    // get the tree size by currentPeriod - genesisPeriod
     const currentPeriod = this.getCurrentPeriod();
     let startPeriod = this.genesisPeriod;
-    let startCommittee = this.genesisCommittee;
+
-    console.log(
+    let lastCommitteeHash: Uint8Array = this.getCommitteeHash(
-      `Sync started from period(${startPeriod}) to period(${currentPeriod})`
+      this.genesisCommittee
     );
 
-    const { syncCommittee, period } = await this.syncProver(
+    for (let period = startPeriod + 1; period <= currentPeriod; period++) {
-      startPeriod,
-      currentPeriod,
-      startCommittee
-    );
-    if (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 recieved ${updatePeriod}`
-      );
-      return false;
-    }
-
-    const prevCommitteeFast = this.deserializeSyncCommittee(prevCommittee);
       try {
-      // check if the update has valid signatures
+        lastCommitteeHash = await this.prover.getCommitteeHash(
-      await assertValidLightClientUpdate(
+          period,
-        this.config.chainConfig,
+          currentPeriod,
-        prevCommitteeFast,
+          DEFAULT_BATCH_SIZE
-        update
+        );
+      } catch (e: any) {
+        throw new Error(
+          `failed to fetch committee hash for prover at period(${period}): ${e.meessage}`
         );
-      return update.nextSyncCommittee.pubkeys;
-    } catch (e) {
-      console.error(e);
-      return false;
       }
     }
+    return this.getCommittee(currentPeriod, lastCommitteeHash);
+  }
 
-  protected async getLatestExecution(): Promise<ExecutionInfo | null> {
+  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.prover.getCommittee(period);
+    const committeeHash = this.getCommitteeHash(committee);
+    if (!isUint8ArrayEq(committeeHash, expectedCommitteeHash as Uint8Array))
+      throw new Error("prover responded with an incorrect committee");
+    return committee;
+  }
+
+  private async getLatestExecution(): Promise<ExecutionInfo | null> {
     const updateJSON = await this.prover.callback(
-      "/eth/v1/beacon/light_client/optimistic_update"
+      "consensus_optimistic_update"
     );
     const update = this.optimisticUpdateFromJSON(updateJSON);
     const verify = await this.optimisticUpdateVerify(
@@ -276,11 +222,13 @@ export default class Client {
     );
   }
 
-  protected async getExecutionFromBlockRoot(
+  private async getExecutionFromBlockRoot(
     slot: bigint,
     expectedBlockRoot: Bytes32
   ): Promise<ExecutionInfo> {
-    const res = await this.prover.callback(`/eth/v2/beacon/blocks/${slot}`);
+    const res = await this.prover.callback("consensus_block", {
+      block: slot,
+    });
     const blockJSON = res.message.body;
     const block = bellatrix.ssz.BeaconBlockBody.fromJson(blockJSON);
     const blockRoot = toHexString(
@@ -311,4 +259,10 @@ export default class Client {
   private deserializePubkeys(pubkeys: Uint8Array[]): PublicKey[] {
     return pubkeys.map((pk) => bls.PublicKey.fromBytes(pk));
   }
+  private getCommitteeHash(committee: Uint8Array[]): Uint8Array {
+    return digest(concatUint8Array(committee));
+  }
+  private optimisticUpdateFromJSON(update: any): OptimisticUpdate {
+    return altair.ssz.LightClientOptimisticUpdate.fromJson(update);
+  }
 }

src/client/interfaces.ts

@@ -1,11 +1,15 @@
-import { AsyncOrSync } from "ts-essentials";
 import { LightClientUpdate } from "./types.js";
 
 export interface IProver {
   get callback(): Function;
-  getSyncUpdate(
+
+  getCommittee(period: number | "latest"): Promise<Uint8Array[]>;
+
+  getCommitteeHash(
     period: number,
     currentPeriod: number,
-    cacheCount: number
+    count: number
-  ): AsyncOrSync<LightClientUpdate>;
+  ): Promise<Uint8Array>;
+
+  getSyncUpdate(period: number): Promise<LightClientUpdate>;
 }

src/client/prover.ts

@@ -1,9 +1,10 @@
 import * as altair from "@lodestar/types/altair";
 import { IProver } from "./interfaces.js";
 import { LightClientUpdate } from "./types.js";
+import { CommitteeSSZ, HashesSSZ, LightClientUpdateSSZ } from "./ssz.js";
 
 export default class Prover implements IProver {
-  cachedSyncUpdate: Map<number, LightClientUpdate> = new Map();
+  cachedHashes: Map<number, Uint8Array> = new Map();
 
   constructor(callback: Function) {
     this._callback = callback;
@@ -15,28 +16,38 @@ export default class Prover implements IProver {
     return this._callback;
   }
 
-  async _getSyncUpdates(
+  async getCommittee(period: number | "latest"): Promise<Uint8Array[]> {
-    startPeriod: number,
+    const res = await this.callback("consensus_committee_period", { period });
-    maxCount: number
+    return CommitteeSSZ.deserialize(Uint8Array.from(Object.values(res)));
-  ): Promise<LightClientUpdate[]> {
-    const res = await this._callback(
-      `/eth/v1/beacon/light_client/updates?start_period=${startPeriod}&count=${maxCount}`
-    );
-    return res.map((u: any) => altair.ssz.LightClientUpdate.fromJson(u.data));
   }
 
-  async getSyncUpdate(
+  async getSyncUpdate(period: number): Promise<LightClientUpdate> {
+    const res = await this.callback("consensus_committee_period", { period });
+    return LightClientUpdateSSZ.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<LightClientUpdate> {
+  ): Promise<Uint8Array> {
-    const _cacheCount = Math.min(currentPeriod - period + 1, cacheCount);
+    const _count = Math.min(currentPeriod - period + 1, cacheCount);
-    if (!this.cachedSyncUpdate.has(period)) {
+    if (!this.cachedHashes.has(period)) {
-      const vals = await this._getSyncUpdates(period, _cacheCount);
+      const vals = await this._getHashes(period, _count);
-      for (let i = 0; i < _cacheCount; i++) {
+      for (let i = 0; i < _count; i++) {
-        this.cachedSyncUpdate.set(period + i, vals[i]);
+        this.cachedHashes.set(period + i, vals[i]);
       }
     }
-    return this.cachedSyncUpdate.get(period)!;
+    return this.cachedHashes.get(period)!;
   }
 }

src/index.ts

@@ -1,6 +1,5 @@
 import { ActiveQuery, addHandler, handleMessage } from "libkmodule";
 import { createClient, RpcNetwork } from "@lumeweb/kernel-rpc-client";
-import { ConsensusRequest, ExecutionRequest } from "./types.js";
 import Client from "./client/client.js";
 import { Prover } from "./client/index.js";
 
@@ -65,27 +64,22 @@ async function handleRpcMethod(aq: ActiveQuery) {
   );
 }
 
-async function consensusHandler(endpoint: string) {
+async function consensusHandler(method: string, data: any) {
-  let query;
-
   while (true) {
-    query = await rpc.simpleQuery({
+    let query = await rpc.simpleQuery({
       query: {
         module: "eth",
-        method: "consensus_request",
+        method,
-        data: {
+        data,
-          method: "GET",
-          path: endpoint,
-        } as ConsensusRequest,
       },
       options: {
         relayTimeout: 10,
         queryTimeout: 10,
       },
     });
-    console.log("consensusHandler", endpoint);
 
     const ret = await query.result;
+
     if (ret.data) {
       return ret.data;
     }
@@ -93,6 +87,7 @@ async function consensusHandler(endpoint: string) {
 }
 
 async function executionHandler(data: Map<string, string | any>) {
+  while (true) {
     let query = await rpc.simpleQuery({
       query: {
         module: "eth",
@@ -101,15 +96,15 @@ async function executionHandler(data: Map<string, string | any>) {
       },
     });
 
-  console.log("executionHandler", data);
-
     let ret = await query.result;
 
+    if (ret.data) {
       return ret.data;
     }
+  }
+}
 
 async function setup() {
-  console.time("setup");
   rpc = createClient();
   // @ts-ignore
   await (

src/types.ts

@@ -1,8 +0,0 @@
-export interface ConsensusRequest extends RequestInit {
-  path: string;
-}
-
-export interface ExecutionRequest {
-  method: string;
-  params: string;
-}