feat: beacon node process electra attestations EIP-7549 (ChainSafe#6738)

* Process attestations in block

* Fix check-types

* Address comments

Author: ensi321

packages/beacon-node/src/chain/blocks/importBlock.ts

@@ -69,6 +69,7 @@ export async function importBlock(
   const prevFinalizedEpoch = this.forkChoice.getFinalizedCheckpoint().epoch;
   const blockDelaySec = (fullyVerifiedBlock.seenTimestampSec - postState.genesisTime) % this.config.SECONDS_PER_SLOT;
   const recvToValLatency = Date.now() / 1000 - (opts.seenTimestampSec ?? Date.now() / 1000);
+  const fork = this.config.getForkSeq(blockSlot);
 
   // this is just a type assertion since blockinput with dataPromise type will not end up here
   if (blockInput.type === BlockInputType.dataPromise) {
@@ -148,7 +149,8 @@ export async function importBlock(
 
     for (const attestation of attestations) {
       try {
-        const indexedAttestation = postState.epochCtx.getIndexedAttestation(attestation);
+        // TODO Electra: figure out how to reuse the attesting indices computed from state transition
+        const indexedAttestation = postState.epochCtx.getIndexedAttestation(fork, attestation);
         const {target, beaconBlockRoot} = attestation.data;
 
         const attDataRoot = toHexString(ssz.phase0.AttestationData.hashTreeRoot(indexedAttestation.data));

packages/beacon-node/test/spec/presets/fork_choice.test.ts

@@ -137,7 +137,10 @@ const forkChoiceTest =
               if (!attestation) throw Error(`No attestation ${step.attestation}`);
               const headState = chain.getHeadState();
               const attDataRootHex = toHexString(ssz.phase0.AttestationData.hashTreeRoot(attestation.data));
-              chain.forkChoice.onAttestation(headState.epochCtx.getIndexedAttestation(attestation), attDataRootHex);
+              chain.forkChoice.onAttestation(
+                headState.epochCtx.getIndexedAttestation(ForkSeq[fork], attestation),
+                attDataRootHex
+              );
             }
 
             // attester slashing step

packages/state-transition/src/block/processAttestationPhase0.ts

@@ -1,7 +1,8 @@
 import {toHexString} from "@chainsafe/ssz";
-import {Slot, phase0, ssz} from "@lodestar/types";
+import {Slot, allForks, electra, phase0, ssz} from "@lodestar/types";
 
 import {MIN_ATTESTATION_INCLUSION_DELAY, SLOTS_PER_EPOCH, ForkSeq} from "@lodestar/params";
+import {assert} from "@lodestar/utils";
 import {computeEpochAtSlot} from "../util/index.js";
 import {CachedBeaconStatePhase0, CachedBeaconStateAllForks} from "../types.js";
 import {isValidIndexedAttestation} from "./index.js";
@@ -51,27 +52,22 @@ export function processAttestationPhase0(
     state.previousEpochAttestations.push(pendingAttestation);
   }
 
-  if (!isValidIndexedAttestation(state, epochCtx.getIndexedAttestation(attestation), verifySignature)) {
+  if (!isValidIndexedAttestation(state, epochCtx.getIndexedAttestation(ForkSeq.phase0, attestation), verifySignature)) {
     throw new Error("Attestation is not valid");
   }
 }
 
 export function validateAttestation(
   fork: ForkSeq,
   state: CachedBeaconStateAllForks,
-  attestation: phase0.Attestation
+  attestation: allForks.Attestation
 ): void {
   const {epochCtx} = state;
   const slot = state.slot;
   const data = attestation.data;
   const computedEpoch = computeEpochAtSlot(data.slot);
   const committeeCount = epochCtx.getCommitteeCountPerSlot(computedEpoch);
-  if (!(data.index < committeeCount)) {
-    throw new Error(
-      "Attestation committee index not within current committee count: " +
-        `committeeIndex=${data.index} committeeCount=${committeeCount}`
-    );
-  }
+
   if (!(data.target.epoch === epochCtx.previousShuffling.epoch || data.target.epoch === epochCtx.epoch)) {
     throw new Error(
       "Attestation target epoch not in previous or current epoch: " +
@@ -93,12 +89,45 @@ export function validateAttestation(
     );
   }
 
-  const committee = epochCtx.getBeaconCommittee(data.slot, data.index);
-  if (attestation.aggregationBits.bitLen !== committee.length) {
-    throw new Error(
-      "Attestation aggregation bits length does not match committee length: " +
-        `aggregationBitsLength=${attestation.aggregationBits.bitLen} committeeLength=${committee.length}`
+  if (fork >= ForkSeq.electra) {
+    assert.equal(data.index, 0, `AttestationData.index must be zero: index=${data.index}`);
+    const attestationElectra = attestation as electra.Attestation;
+    const committeeBitsLength = attestationElectra.committeeBits.bitLen;
+
+    if (committeeBitsLength > committeeCount) {
+      throw new Error(
+        `Attestation committee bits length are longer than number of committees: committeeBitsLength=${committeeBitsLength} numCommittees=${committeeCount}`
+      );
+    }
+
+    // TODO Electra: this should be obsolete soon when the spec switches to committeeIndices
+    const committeeIndices = attestationElectra.committeeBits.getTrueBitIndexes();
+
+    // Get total number of attestation participant of every committee specified
+    const participantCount = committeeIndices
+      .map((committeeIndex) => epochCtx.getBeaconCommittee(data.slot, committeeIndex).length)
+      .reduce((acc, committeeSize) => acc + committeeSize, 0);
+
+    assert.equal(
+      attestationElectra.aggregationBits.bitLen,
+      participantCount,
+      `Attestation aggregation bits length does not match total number of committee participant aggregationBitsLength=${attestation.aggregationBits.bitLen} participantCount=${participantCount}`
     );
+  } else {
+    if (!(data.index < committeeCount)) {
+      throw new Error(
+        "Attestation committee index not within current committee count: " +
+          `committeeIndex=${data.index} committeeCount=${committeeCount}`
+      );
+    }
+
+    const committee = epochCtx.getBeaconCommittee(data.slot, data.index);
+    if (attestation.aggregationBits.bitLen !== committee.length) {
+      throw new Error(
+        "Attestation aggregation bits length does not match committee length: " +
+          `aggregationBitsLength=${attestation.aggregationBits.bitLen} committeeLength=${committee.length}`
+      );
+    }
   }
 }
 

packages/state-transition/src/block/processAttestations.ts

@@ -1,4 +1,4 @@
-import {phase0} from "@lodestar/types";
+import {allForks} from "@lodestar/types";
 import {ForkSeq} from "@lodestar/params";
 import {CachedBeaconStateAllForks, CachedBeaconStateAltair, CachedBeaconStatePhase0} from "../types.js";
 import {processAttestationPhase0} from "./processAttestationPhase0.js";
@@ -10,7 +10,7 @@ import {processAttestationsAltair} from "./processAttestationsAltair.js";
 export function processAttestations(
   fork: ForkSeq,
   state: CachedBeaconStateAllForks,
-  attestations: phase0.Attestation[],
+  attestations: allForks.Attestation[],
   verifySignatures = true
 ): void {
   if (fork === ForkSeq.phase0) {

packages/state-transition/src/block/processAttestationsAltair.ts

@@ -1,5 +1,5 @@
 import {byteArrayEquals} from "@chainsafe/ssz";
-import {Epoch, phase0} from "@lodestar/types";
+import {Epoch, allForks, phase0} from "@lodestar/types";
 import {intSqrt} from "@lodestar/utils";
 
 import {
@@ -32,7 +32,7 @@ const SLOTS_PER_EPOCH_SQRT = intSqrt(SLOTS_PER_EPOCH);
 export function processAttestationsAltair(
   fork: ForkSeq,
   state: CachedBeaconStateAltair,
-  attestations: phase0.Attestation[],
+  attestations: allForks.Attestation[],
   verifySignature = true
 ): void {
   const {epochCtx} = state;
@@ -49,8 +49,7 @@ export function processAttestationsAltair(
     validateAttestation(fork, state, attestation);
 
     // Retrieve the validator indices from the attestation participation bitfield
-    const committeeIndices = epochCtx.getBeaconCommittee(data.slot, data.index);
-    const attestingIndices = attestation.aggregationBits.intersectValues(committeeIndices);
+    const attestingIndices = epochCtx.getAttestingIndices(fork, attestation);
 
     // this check is done last because its the most expensive (if signature verification is toggled on)
     // TODO: Why should we verify an indexed attestation that we just created? If it's just for the signature

packages/state-transition/src/cache/epochCache.ts

@@ -2,7 +2,17 @@ import {CoordType, PublicKey} from "@chainsafe/bls/types";
 import bls from "@chainsafe/bls";
 import * as immutable from "immutable";
 import {fromHexString} from "@chainsafe/ssz";
-import {BLSSignature, CommitteeIndex, Epoch, Slot, ValidatorIndex, phase0, SyncPeriod} from "@lodestar/types";
+import {
+  BLSSignature,
+  CommitteeIndex,
+  Epoch,
+  Slot,
+  ValidatorIndex,
+  phase0,
+  SyncPeriod,
+  allForks,
+  electra,
+} from "@lodestar/types";
 import {createBeaconConfig, BeaconConfig, ChainConfig} from "@lodestar/config";
 import {
   ATTESTATION_SUBNET_COUNT,
@@ -645,15 +655,47 @@ export class EpochCache {
    * Return the beacon committee at slot for index.
    */
   getBeaconCommittee(slot: Slot, index: CommitteeIndex): Uint32Array {
+    return this.getBeaconCommittees(slot, [index]);
+  }
+
+  /**
+   * Return a single Uint32Array representing concatted committees of indices
+   */
+  getBeaconCommittees(slot: Slot, indices: CommitteeIndex[]): Uint32Array {
+    if (indices.length === 0) {
+      throw new Error("Attempt to get committees without providing CommitteeIndex");
+    }
+
     const slotCommittees = this.getShufflingAtSlot(slot).committees[slot % SLOTS_PER_EPOCH];
-    if (index >= slotCommittees.length) {
-      throw new EpochCacheError({
-        code: EpochCacheErrorCode.COMMITTEE_INDEX_OUT_OF_RANGE,
-        index,
-        maxIndex: slotCommittees.length,
-      });
+    const committees = [];
+
+    for (const index of indices) {
+      if (index >= slotCommittees.length) {
+        throw new EpochCacheError({
+          code: EpochCacheErrorCode.COMMITTEE_INDEX_OUT_OF_RANGE,
+          index,
+          maxIndex: slotCommittees.length,
+        });
+      }
+      committees.push(slotCommittees[index]);
+    }
+
+    // Early return if only one index
+    if (committees.length === 1) {
+      return committees[0];
+    }
+
+    // Create a new Uint32Array to flatten `committees`
+    const totalLength = committees.reduce((acc, curr) => acc + curr.length, 0);
+    const result = new Uint32Array(totalLength);
+
+    let offset = 0;
+    for (const committee of committees) {
+      result.set(committee, offset);
+      offset += committee.length;
     }
-    return slotCommittees[index];
+
+    return result;
   }
 
   getCommitteeCountPerSlot(epoch: Epoch): number {
@@ -739,10 +781,9 @@ export class EpochCache {
   /**
    * Return the indexed attestation corresponding to ``attestation``.
    */
-  getIndexedAttestation(attestation: phase0.Attestation): phase0.IndexedAttestation {
-    const {aggregationBits, data} = attestation;
-    const committeeIndices = this.getBeaconCommittee(data.slot, data.index);
-    const attestingIndices = aggregationBits.intersectValues(committeeIndices);
+  getIndexedAttestation(fork: ForkSeq, attestation: allForks.Attestation): allForks.IndexedAttestation {
+    const {data} = attestation;
+    const attestingIndices = this.getAttestingIndices(fork, attestation);
 
     // sort in-place
     attestingIndices.sort((a, b) => a - b);
@@ -753,6 +794,31 @@ export class EpochCache {
     };
   }
 
+  /**
+   * Return indices of validators who attestested in `attestation`
+   */
+  getAttestingIndices(fork: ForkSeq, attestation: allForks.Attestation): number[] {
+    if (fork < ForkSeq.electra) {
+      const {aggregationBits, data} = attestation;
+      const validatorIndices = this.getBeaconCommittee(data.slot, data.index);
+
+      return aggregationBits.intersectValues(validatorIndices);
+    } else {
+      const {aggregationBits, committeeBits, data} = attestation as electra.Attestation;
+
+      // There is a naming conflict on the term `committeeIndices`
+      // In Lodestar it usually means a list of validator indices of participants in a committee
+      // In the spec it means a list of committee indices according to committeeBits
+      // This `committeeIndices` refers to the latter
+      // TODO Electra: resolve the naming conflicts
+      const committeeIndices = committeeBits.getTrueBitIndexes();
+
+      const validatorIndices = this.getBeaconCommittees(data.slot, committeeIndices);
+
+      return aggregationBits.intersectValues(validatorIndices);
+    }
+  }
+
   getCommitteeAssignments(
     epoch: Epoch,
     requestedValidatorIndices: ValidatorIndex[]

packages/state-transition/src/signatureSets/indexedAttestation.ts

@@ -41,7 +41,11 @@ export function getAttestationsSignatureSets(
   state: CachedBeaconStateAllForks,
   signedBlock: allForks.SignedBeaconBlock
 ): ISignatureSet[] {
+  // TODO: figure how to get attesting indices of an attestation once per block processing
   return signedBlock.message.body.attestations.map((attestation) =>
-    getIndexedAttestationSignatureSet(state, state.epochCtx.getIndexedAttestation(attestation))
+    getIndexedAttestationSignatureSet(
+      state,
+      state.epochCtx.getIndexedAttestation(state.epochCtx.config.getForkSeq(signedBlock.message.slot), attestation)
+    )
   );
 }