feat: allow multiple bids compatible with the head view

packages/beacon-node/src/chain/errors/executionPayloadBid.ts

@@ -5,6 +5,7 @@ export enum ExecutionPayloadBidErrorCode {
   BUILDER_NOT_ELIGIBLE = "EXECUTION_PAYLOAD_BID_ERROR_BUILDER_NOT_ELIGIBLE",
   INVALID_BUILDER_VERSION = "EXECUTION_PAYLOAD_BID_ERROR_INVALID_BUILDER_VERSION",
   NON_ZERO_EXECUTION_PAYMENT = "EXECUTION_PAYLOAD_BID_ERROR_NON_ZERO_EXECUTION_PAYMENT",
+  INCOMPATIBLE_WITH_HEAD = "EXECUTION_PAYLOAD_BID_ERROR_INCOMPATIBLE_WITH_HEAD",
   BID_ALREADY_KNOWN = "EXECUTION_PAYLOAD_BID_ERROR_BID_ALREADY_KNOWN",
   BID_TOO_LOW = "EXECUTION_PAYLOAD_BID_ERROR_BID_TOO_LOW",
   BID_TOO_HIGH = "EXECUTION_PAYLOAD_BID_ERROR_BID_TOO_HIGH",
@@ -33,6 +34,13 @@ export type ExecutionPayloadBidErrorType =
       builderIndex: BuilderIndex;
       executionPayment: number;
     }
+  | {
+      code: ExecutionPayloadBidErrorCode.INCOMPATIBLE_WITH_HEAD;
+      slot: Slot;
+      parentBlockRoot: RootHex;
+      parentBlockHash: RootHex;
+      headBlockRoot: RootHex;
+    }
   | {
       code: ExecutionPayloadBidErrorCode.BID_ALREADY_KNOWN;
       builderIndex: BuilderIndex;

packages/beacon-node/src/chain/prepareNextSlot.ts

@@ -173,7 +173,7 @@ export class PrepareNextSlotScheduler {
         // Apply parent payload once here as it's reused by EL prep and SSE emit below
         let stateAfterParentPayload: IBeaconStateViewBellatrix = updatedPrepareState;
         if (isStatePostGloas(updatedPrepareState)) {
-          // Spec: should_build_on_full(store, head) — see produceBlockBody.ts for context.
+          // Spec: should_build_on_full(store, head, slot) - see produceBlockBody.ts for context.
           if (this.chain.forkChoice.shouldBuildOnFull(updatedHead, prepareSlot)) {
             parentBlockHash = updatedPrepareState.latestExecutionPayloadBid.blockHash;
             // Skip applying parent payload unless we're proposing the next slot or have to emit payload_attributes events

packages/beacon-node/src/chain/produceBlock/produceBlockBody.ts

@@ -276,7 +276,7 @@ export async function produceBlockBody<T extends BlockType>(
     let parentExecutionRequests: gloas.ExecutionRequests;
     // Apply parent payload once here as it's reused by EL prep and voluntary exit filtering below
     let stateAfterParentPayload: IBeaconStateViewBellatrix = currentState;
-    // Spec: should_build_on_full(store, head). `parentBlock` is the proposer's head
+    // Spec: should_build_on_full(store, head, slot). `parentBlock` is the proposer's head
     // (set by chain.getProposerHead(slot)). Returns false when the PTC majority signalled
     // the blob data is not available or the payload was not timely, forcing a build on EMPTY (reorg).
     const isBuildingOnFull = this.forkChoice.shouldBuildOnFull(parentBlock, blockSlot);

packages/beacon-node/src/chain/seenCache/seenExecutionPayloadBids.ts

@@ -1,4 +1,4 @@
-import {BuilderIndex, Slot} from "@lodestar/types";
+import {BuilderIndex, RootHex, Slot} from "@lodestar/types";
 import {MapDef} from "@lodestar/utils";
 
 /**
@@ -7,29 +7,42 @@ import {MapDef} from "@lodestar/utils";
 const SLOTS_RETAINED = 2;
 
 /**
- * Tracks execution payload bids we've already seen per (slot, builder).
+ * Tracks execution payload bids we've already seen per
+ * (slot, builder, parent block hash, parent block root).
  */
 export class SeenExecutionPayloadBids {
-  private readonly builderIndexesBySlot = new MapDef<Slot, Set<BuilderIndex>>(() => new Set<BuilderIndex>());
+  private readonly branchesByBuilderBySlot = new MapDef<Slot, MapDef<BuilderIndex, Set<string>>>(
+    () => new MapDef<BuilderIndex, Set<string>>(() => new Set<string>())
+  );
   private lowestPermissibleSlot: Slot = 0;
 
-  isKnown(slot: Slot, builderIndex: BuilderIndex): boolean {
-    return this.builderIndexesBySlot.get(slot)?.has(builderIndex) === true;
+  isKnown(slot: Slot, builderIndex: BuilderIndex, parentBlockHash: RootHex, parentBlockRoot: RootHex): boolean {
+    return (
+      this.branchesByBuilderBySlot.get(slot)?.get(builderIndex)?.has(branchKey(parentBlockHash, parentBlockRoot)) ===
+      true
+    );
   }
 
-  add(slot: Slot, builderIndex: BuilderIndex): void {
+  add(slot: Slot, builderIndex: BuilderIndex, parentBlockHash: RootHex, parentBlockRoot: RootHex): void {
     if (slot < this.lowestPermissibleSlot) {
       throw Error(`slot ${slot} < lowestPermissibleSlot ${this.lowestPermissibleSlot}`);
     }
-    this.builderIndexesBySlot.getOrDefault(slot).add(builderIndex);
+    this.branchesByBuilderBySlot
+      .getOrDefault(slot)
+      .getOrDefault(builderIndex)
+      .add(branchKey(parentBlockHash, parentBlockRoot));
   }
 
   prune(currentSlot: Slot): void {
     this.lowestPermissibleSlot = Math.max(currentSlot - SLOTS_RETAINED, 0);
-    for (const slot of this.builderIndexesBySlot.keys()) {
+    for (const slot of this.branchesByBuilderBySlot.keys()) {
       if (slot < this.lowestPermissibleSlot) {
-        this.builderIndexesBySlot.delete(slot);
+        this.branchesByBuilderBySlot.delete(slot);
       }
     }
   }
 }
+
+function branchKey(parentBlockHash: RootHex, parentBlockRoot: RootHex): string {
+  return `${parentBlockHash}:${parentBlockRoot}`;
+}

packages/beacon-node/src/chain/validation/executionPayloadBid.ts

@@ -1,4 +1,5 @@
 import {PublicKey} from "@chainsafe/blst";
+import {IForkChoice, ProtoBlock} from "@lodestar/fork-choice";
 import {PAYLOAD_BUILDER_VERSION} from "@lodestar/params";
 import {
   computeEpochAtSlot,
@@ -8,7 +9,7 @@ import {
   isGasLimitTargetCompatible,
   isStatePostGloas,
 } from "@lodestar/state-transition";
-import {ValidatorIndex, gloas} from "@lodestar/types";
+import {RootHex, Slot, ValidatorIndex, gloas} from "@lodestar/types";
 import {byteArrayEquals, toHex, toRootHex} from "@lodestar/utils";
 import {getShufflingDependentRoot} from "../../util/dependentRoot.js";
 import {ExecutionPayloadBidError, ExecutionPayloadBidErrorCode, GossipAction} from "../errors/index.js";
@@ -36,12 +37,45 @@ const BID_INCREMENT_CAP_GWEI = 10_000_000;
  * Return the minimum value a new bid must have to be forwarded given the current highest bid.
  * Division before multiplication to stay within safe integer range for max gwei values.
  */
-export function getMinBidValue(currentHighestBid: number): number {
+function getMinBidValue(currentHighestBid: number): number {
   const relativeIncrement = Math.floor(currentHighestBid / 10_000) * BID_INCREMENT_BPS;
   const increment = Math.min(Math.max(BID_INCREMENT_FLOOR_GWEI, relativeIncrement), BID_INCREMENT_CAP_GWEI);
   return currentHighestBid + increment;
 }
 
+/**
+ * Check whether a bid builds on one of the paths compatible with the local head branch.
+ *
+ * The direct parent path is always allowed for proposer-boost reorgs. Otherwise the bid
+ * must build on the local head's full or empty payload variant, as selected for its slot.
+ */
+function isBidCompatibleWithHead(
+  forkChoice: IForkChoice,
+  head: ProtoBlock,
+  bidSlot: Slot,
+  bidParentBlockRoot: RootHex,
+  bidParentBlockHash: RootHex
+): boolean {
+  const buildsOnParentBlock = bidParentBlockRoot === head.parentRoot;
+  const buildsOnParentPayload = bidParentBlockHash === head.parentBlockHash;
+
+  if (buildsOnParentBlock && buildsOnParentPayload) {
+    return true;
+  }
+
+  if (bidParentBlockRoot !== head.blockRoot) {
+    return false;
+  }
+
+  const buildsOnHeadPayload = bidParentBlockHash === head.executionPayloadBlockHash;
+
+  if (forkChoice.shouldBuildOnFull(head, bidSlot)) {
+    return buildsOnHeadPayload;
+  }
+
+  return buildsOnParentPayload;
+}
+
 export async function validateApiExecutionPayloadBid(
   chain: IBeaconChain,
   signedExecutionPayloadBid: gloas.SignedExecutionPayloadBid
@@ -61,8 +95,8 @@ async function validateExecutionPayloadBid(
   signedExecutionPayloadBid: gloas.SignedExecutionPayloadBid
 ): Promise<{proposerIndex: ValidatorIndex}> {
   const bid = signedExecutionPayloadBid.message;
-  const parentBlockRootHex = toRootHex(bid.parentBlockRoot);
-  const parentBlockHashHex = toRootHex(bid.parentBlockHash);
+  const bidParentBlockRoot = toRootHex(bid.parentBlockRoot);
+  const bidParentBlockHash = toRootHex(bid.parentBlockHash);
 
   // [IGNORE] `bid.slot` is the current slot, or the next slot (`bid.slot - 1` is current), allowing for `MAXIMUM_GOSSIP_CLOCK_DISPARITY`.
   if (
@@ -76,14 +110,40 @@ async function validateExecutionPayloadBid(
     });
   }
 
+  // [IGNORE] The bid is compatible with the current head branch.
+  const head = chain.forkChoice.getHead();
+  if (!isBidCompatibleWithHead(chain.forkChoice, head, bid.slot, bidParentBlockRoot, bidParentBlockHash)) {
+    throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
+      code: ExecutionPayloadBidErrorCode.INCOMPATIBLE_WITH_HEAD,
+      slot: bid.slot,
+      parentBlockRoot: bidParentBlockRoot,
+      parentBlockHash: bidParentBlockHash,
+      headBlockRoot: head.blockRoot,
+    });
+  }
+
+  // [IGNORE] this is the first signed bid seen with a valid signature from the given builder for
+  // the tuple `(bid.slot, bid.parent_block_hash, bid.parent_block_root)`.
+  // Entries are only added after signature verification, so known tuples can be dropped before
+  // state regeneration and the other expensive validation steps.
+  if (chain.seenExecutionPayloadBids.isKnown(bid.slot, bid.builderIndex, bidParentBlockHash, bidParentBlockRoot)) {
+    throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
+      code: ExecutionPayloadBidErrorCode.BID_ALREADY_KNOWN,
+      builderIndex: bid.builderIndex,
+      slot: bid.slot,
+      parentBlockRoot: bidParentBlockRoot,
+      parentBlockHash: bidParentBlockHash,
+    });
+  }
+
   // [IGNORE] `bid.parent_block_root` is the hash tree root of a known beacon block in fork choice.
   // Moved earlier than the spec ordering so we can derive the proposer dependent root for the
   // proposer-preferences lookup below from a known fork-choice block.
-  const parentBlock = chain.forkChoice.getBlockHexDefaultStatus(parentBlockRootHex);
+  const parentBlock = chain.forkChoice.getBlockHexDefaultStatus(bidParentBlockRoot);
   if (parentBlock === null) {
     throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
       code: ExecutionPayloadBidErrorCode.UNKNOWN_BLOCK_ROOT,
-      parentBlockRoot: parentBlockRootHex,
+      parentBlockRoot: bidParentBlockRoot,
     });
   }
 
@@ -122,7 +182,7 @@ async function validateExecutionPayloadBid(
     throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
       code: ExecutionPayloadBidErrorCode.NO_MATCHING_PROPOSER_PREFERENCES,
       slot: bid.slot,
-      parentBlockRoot: parentBlockRootHex,
+      parentBlockRoot: bidParentBlockRoot,
       dependentRoot: "unknown",
     });
   }
@@ -132,7 +192,7 @@ async function validateExecutionPayloadBid(
     throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
       code: ExecutionPayloadBidErrorCode.NO_MATCHING_PROPOSER_PREFERENCES,
       slot: bid.slot,
-      parentBlockRoot: parentBlockRootHex,
+      parentBlockRoot: bidParentBlockRoot,
       dependentRoot: dependentRootHex,
     });
   }
@@ -143,7 +203,7 @@ async function validateExecutionPayloadBid(
     .catch(() => {
       throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
         code: ExecutionPayloadBidErrorCode.UNKNOWN_BLOCK_ROOT,
-        parentBlockRoot: parentBlockRootHex,
+        parentBlockRoot: bidParentBlockRoot,
       });
     });
 
@@ -208,11 +268,11 @@ async function validateExecutionPayloadBid(
   // payload's hash) and EMPTY parents (EMPTY/PENDING variants carry the inherited parent
   // payload's hash, since the new block doesn't have its own payload). Variant carries the
   // executed payload's gas_limit, which we use as `parent_gas_limit` below.
-  const parentPayloadVariant = chain.forkChoice.getBlockHexAndBlockHash(parentBlockRootHex, parentBlockHashHex);
+  const parentPayloadVariant = chain.forkChoice.getBlockHexAndBlockHash(bidParentBlockRoot, bidParentBlockHash);
   if (parentPayloadVariant === null || parentPayloadVariant.executionPayloadBlockHash === null) {
     throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
       code: ExecutionPayloadBidErrorCode.UNKNOWN_PARENT_BLOCK_HASH,
-      parentBlockHash: parentBlockHashHex,
+      parentBlockHash: bidParentBlockHash,
     });
   }
 
@@ -245,23 +305,12 @@ async function validateExecutionPayloadBid(
     });
   }
 
-  // [IGNORE] this is the first signed bid seen with a valid signature from the given builder for this slot.
-  if (chain.seenExecutionPayloadBids.isKnown(bid.slot, bid.builderIndex)) {
-    throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
-      code: ExecutionPayloadBidErrorCode.BID_ALREADY_KNOWN,
-      builderIndex: bid.builderIndex,
-      slot: bid.slot,
-      parentBlockRoot: parentBlockRootHex,
-      parentBlockHash: parentBlockHashHex,
-    });
-  }
-
   // [IGNORE] this bid is the highest value bid seen for the tuple
   // `(bid.slot, bid.parent_block_hash, bid.parent_block_root)`.
   // As a DoS prevention measure, the bid must also exceed the current highest bid by a minimum
   // increment, see https://github.com/ethereum/consensus-specs/pull/4831. This prevents spam
   // from builders submitting numerous bids with minimal value increments.
-  const bestBid = chain.executionPayloadBidPool.getBestBid(bid.slot, parentBlockHashHex, parentBlockRootHex);
+  const bestBid = chain.executionPayloadBidPool.getBestBid(bid.slot, bidParentBlockHash, bidParentBlockRoot);
   if (bestBid !== null && bid.value < getMinBidValue(bestBid.message.value)) {
     throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
       code: ExecutionPayloadBidErrorCode.BID_TOO_LOW,
@@ -306,8 +355,20 @@ async function validateExecutionPayloadBid(
     });
   }
 
+  // Repeat the seen check after the awaited signature verification to prevent concurrent bids
+  // for the same builder and tuple from both passing validation.
+  if (chain.seenExecutionPayloadBids.isKnown(bid.slot, bid.builderIndex, bidParentBlockHash, bidParentBlockRoot)) {
+    throw new ExecutionPayloadBidError(GossipAction.IGNORE, {
+      code: ExecutionPayloadBidErrorCode.BID_ALREADY_KNOWN,
+      builderIndex: bid.builderIndex,
+      slot: bid.slot,
+      parentBlockRoot: bidParentBlockRoot,
+      parentBlockHash: bidParentBlockHash,
+    });
+  }
+
   // Valid
-  chain.seenExecutionPayloadBids.add(bid.slot, bid.builderIndex);
+  chain.seenExecutionPayloadBids.add(bid.slot, bid.builderIndex, bidParentBlockHash, bidParentBlockRoot);
 
   return {proposerIndex: proposerPreferences.message.validatorIndex};
 }

packages/beacon-node/src/network/processor/index.ts

@@ -461,7 +461,8 @@ export class NetworkProcessor {
           break;
         }
         case GossipType.execution_payload_bid: {
-          // instead of searching for the message root, this searches for the parent root
+          // Search for the parent independently of current head compatibility. A bid may arrive
+          // before its parent block, so compatibility is checked later during gossip validation.
           const parentBlockRoot = getParentBlockRootFromSignedExecutionPayloadBidSerialized(message.msg.data);
           const parentBlockHash = getParentBlockHashFromSignedExecutionPayloadBidSerialized(message.msg.data);
           if (

packages/fork-choice/src/forkChoice/forkChoice.ts

@@ -388,7 +388,7 @@ export class ForkChoice implements IForkChoice {
     return this.protoArray.shouldExtendPayload(blockRoot, this.proposerBoostRoot);
   }
 
-  /** Spec: should_build_on_full(store, head) */
+  /** Spec: should_build_on_full(store, head, slot) */
   shouldBuildOnFull(head: ProtoBlock, slot: Slot): boolean {
     return this.protoArray.shouldBuildOnFull(head, slot);
   }

packages/fork-choice/src/forkChoice/interface.ts

@@ -270,7 +270,7 @@ export interface IForkChoice {
   getBlockHexDefaultStatus(blockRoot: RootHex): ProtoBlock | null;
   getBlockHexAndBlockHash(blockRoot: RootHex, blockHash: RootHex): ProtoBlock | null;
   shouldExtendPayload(blockRoot: RootHex): boolean;
-  /** Spec: should_build_on_full(store, head) */
+  /** Spec: should_build_on_full(store, head, slot) */
   shouldBuildOnFull(head: ProtoBlock, slot: Slot): boolean;
   getFinalizedBlock(): ProtoBlock;
   getJustifiedBlock(): ProtoBlock;

packages/fork-choice/src/protoArray/protoArray.ts

@@ -855,7 +855,7 @@ export class ProtoArray {
   }
 
   /**
-   * Spec: should_build_on_full(store, head)
+   * Spec: should_build_on_full(store, head, slot)
    *
    * The proposer is forced to build on the EMPTY variant (effectively reorging)
    * when the PTC majority voted that the blob data is not available or that the

packages/fork-choice/test/unit/protoArray/gloas.test.ts

@@ -1143,7 +1143,7 @@ describe("Gloas Fork Choice", () => {
     });
   });
 
-  describe("shouldBuildOnFull() — Spec: should_build_on_full(store, head)", () => {
+  describe("shouldBuildOnFull() - Spec: should_build_on_full(store, head, slot)", () => {
     let protoArray: ProtoArray;
 
     beforeEach(() => {