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feat: SSZ-REST Engine API transport #8994

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de2fba7
feat: EIP-8161 SSZ-REST Engine API transport
Giulio2002 Mar 5, 2026
36529c5
refactor: adopt execution-apis PR #764 RESTful paths for SSZ-REST
Giulio2002 Mar 5, 2026
f10047c
refactor: replace Union[None, T] with List[T, 1] for optional SSZ fields
Giulio2002 Mar 5, 2026
66b6604
Remove --execution.sszRestUrl flag, auto-derive from engine URL
Giulio2002 Mar 6, 2026
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210 changes: 208 additions & 2 deletions packages/beacon-node/src/execution/engine/http.ts
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Original file line number Diff line number Diff line change
@@ -1,9 +1,9 @@
import {Logger} from "@lodestar/logger";
import {ForkName, ForkPostFulu, ForkPreFulu, ForkSeq, SLOTS_PER_EPOCH, isForkPostFulu} from "@lodestar/params";
import {BlobsBundle, ExecutionPayload, ExecutionRequests, Root, RootHex, Wei} from "@lodestar/types";
import {BlobsBundle, ExecutionPayload, ExecutionRequests, Root, RootHex, Wei, ssz as sszCodecs} from "@lodestar/types";
import {BlobAndProof} from "@lodestar/types/deneb";
import {BlobAndProofV2} from "@lodestar/types/fulu";
import {strip0xPrefix} from "@lodestar/utils";
import {fromHex, strip0xPrefix} from "@lodestar/utils";
import {Metrics} from "../../metrics/index.js";
import {EPOCHS_PER_BATCH} from "../../sync/constants.js";
import {getLodestarClientVersion} from "../../util/metadata.js";
Expand All @@ -27,6 +27,17 @@ import {
ReqOpts,
} from "./jsonRpcHttpClient.js";
import {PayloadIdCache} from "./payloadIdCache.js";
import {SszRestClient, isSszRestNetworkError} from "./sszRestClient.js";
import {
decodeForkchoiceUpdatedResponse,
decodeGetBlobsResponse,
decodeGetPayloadResponse,
decodePayloadStatus,
encodeForkchoiceUpdatedRequest,
encodeGetBlobsRequest,
encodeGetPayloadRequest,
encodeNewPayloadRequest,
} from "./sszRestEncoding.js";
import {
BLOB_AND_PROOF_V2_RPC_BYTES,
EngineApiRpcParamTypes,
Expand Down Expand Up @@ -139,6 +150,10 @@ export class ExecutionEngineHttp implements IExecutionEngine {
clientVersion?: ClientVersion | null;

readonly payloadIdCache = new PayloadIdCache();

/** EIP-8161: SSZ-REST client, null if not configured */
private readonly sszRestClient: SszRestClient | null;

/**
* A queue to serialize the fcUs and newPayloads calls:
*
Expand Down Expand Up @@ -170,6 +185,21 @@ export class ExecutionEngineHttp implements IExecutionEngine {
this.logger = logger;
this.metrics = metrics ?? null;

// EIP-8161: Initialize SSZ-REST client using the same Engine API URL.
// SSZ-REST routes are served on the same port under /engine/* paths.
{
const engineUrl = opts?.urls?.[0] ?? "http://localhost:8551";
const baseUrl = engineUrl.replace(/\/+$/, "");
this.sszRestClient = new SszRestClient({
baseUrl,
jwtSecretHex: opts?.jwtSecretHex,
jwtId: opts?.jwtId,
jwtVersion: opts?.jwtVersion,
timeout: opts?.timeout,
});
this.logger.info("SSZ-REST Engine API transport enabled (EIP-8161)", {url: baseUrl});
}

this.rpc.emitter.on(JsonRpcHttpClientEvent.ERROR, ({error}) => {
this.updateEngineState(getExecutionEngineState({payloadError: error, oldState: this.state}));
});
Expand Down Expand Up @@ -215,6 +245,44 @@ export class ExecutionEngineHttp implements IExecutionEngine {
parentBlockRoot?: Root,
executionRequests?: ExecutionRequests
): Promise<ExecutePayloadResponse> {
// EIP-8161: Try SSZ-REST first, fall back to JSON-RPC on network errors
if (this.sszRestClient) {
try {
const version =
ForkSeq[fork] >= ForkSeq.fulu ? 5 : ForkSeq[fork] >= ForkSeq.electra ? 4 : ForkSeq[fork] >= ForkSeq.deneb ? 3 : ForkSeq[fork] >= ForkSeq.capella ? 2 : 1;
Comment on lines +251 to +252
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@gemini-code-assist gemini-code-assist bot Mar 5, 2026

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medium

This version selection logic is duplicated in the getPayload method (lines 554-555). To improve maintainability and adhere to the DRY (Don't Repeat Yourself) principle, consider extracting this logic into a dedicated helper function. For example:

function getPayloadApiVersion(fork: ForkName): number {
  const forkSeq = ForkSeq[fork];
  if (forkSeq >= ForkSeq.fulu) return 5;
  if (forkSeq >= ForkSeq.electra) return 4;
  if (forkSeq >= ForkSeq.deneb) return 3;
  if (forkSeq >= ForkSeq.capella) return 2;
  return 1;
}

You can then call this function here and in getPayload.

const path = `/engine/v${version}/payloads`;
const body = encodeNewPayloadRequest(fork, executionPayload, versionedHashes, parentBlockRoot, executionRequests);
const resp = await this.sszRestClient.doRequest(path, body);
const decoded = decodePayloadStatus(resp);
const status = decoded.status as ExecutionPayloadStatus;
this.updateEngineState(getExecutionEngineState({payloadStatus: status, oldState: this.state}));

switch (status) {
case ExecutionPayloadStatus.VALID:
return {status, latestValidHash: decoded.latestValidHash ?? "0x0", validationError: null};
case ExecutionPayloadStatus.INVALID:
return {status, latestValidHash: decoded.latestValidHash, validationError: decoded.validationError};
case ExecutionPayloadStatus.SYNCING:
case ExecutionPayloadStatus.ACCEPTED:
return {status, latestValidHash: null, validationError: null};
case ExecutionPayloadStatus.INVALID_BLOCK_HASH:
return {status, latestValidHash: null, validationError: decoded.validationError ?? "Malformed block"};
default:
return {
status: ExecutionPayloadStatus.ELERROR,
latestValidHash: null,
validationError: `Invalid EL status on executePayload: ${status}`,
};
}
} catch (e) {
if (isSszRestNetworkError(e)) {
this.logger.debug("SSZ-REST newPayload failed, falling back to JSON-RPC", {error: (e as Error).message});
} else {
throw e;
}
}
}

const method =
ForkSeq[fork] >= ForkSeq.electra
? "engine_newPayloadV4"
Expand Down Expand Up @@ -345,6 +413,60 @@ export class ExecutionEngineHttp implements IExecutionEngine {
finalizedBlockHash: RootHex,
payloadAttributes?: PayloadAttributes
): Promise<PayloadId | null> {
// EIP-8161: Try SSZ-REST first, fall back to JSON-RPC on network errors
if (this.sszRestClient) {
try {
const version = ForkSeq[fork] >= ForkSeq.deneb ? 3 : ForkSeq[fork] >= ForkSeq.capella ? 2 : 1;
const path = `/engine/v${version}/forkchoice`;
const headBytes = fromHex(headBlockHash);
const safeBytes = fromHex(safeBlockHash);
const finalizedBytes = fromHex(finalizedBlockHash);
const body = encodeForkchoiceUpdatedRequest(headBytes, safeBytes, finalizedBytes, payloadAttributes);
const resp = await this.sszRestClient.doRequest(path, body);
const decoded = decodeForkchoiceUpdatedResponse(resp);
const status = decoded.payloadStatus.status as ExecutionPayloadStatus;

this.updateEngineState(getExecutionEngineState({payloadStatus: status, oldState: this.state}));
this.metrics?.engineNotifyForkchoiceUpdateResult.inc({result: status});

const payloadAttributesRpc = payloadAttributes ? serializePayloadAttributes(payloadAttributes) : undefined;

switch (status) {
case ExecutionPayloadStatus.VALID:
if (payloadAttributesRpc) {
if (!decoded.payloadId || decoded.payloadId === "0x") {
throw Error(`Received invalid payloadId=${decoded.payloadId}`);
}
this.payloadIdCache.add({headBlockHash, finalizedBlockHash, ...payloadAttributesRpc}, decoded.payloadId);
void this.prunePayloadIdCache();
}
return decoded.payloadId !== "0x" ? decoded.payloadId : null;

case ExecutionPayloadStatus.SYNCING:
if (payloadAttributes) {
throw Error("Execution Layer Syncing");
}
return null;

case ExecutionPayloadStatus.INVALID:
throw Error(
`Invalid ${payloadAttributes ? "prepare payload" : "forkchoice request"}, validationError=${
decoded.payloadStatus.validationError ?? ""
}`
);

default:
throw Error(`Unknown status ${status}`);
}
} catch (e) {
if (isSszRestNetworkError(e)) {
this.logger.debug("SSZ-REST forkchoiceUpdate failed, falling back to JSON-RPC", {error: (e as Error).message});
} else {
throw e;
}
}
}

// Once on capella, should this need to be permanently switched to v2 when payload attrs
// not provided
const method =
Expand Down Expand Up @@ -422,6 +544,42 @@ export class ExecutionEngineHttp implements IExecutionEngine {
executionRequests?: ExecutionRequests;
shouldOverrideBuilder?: boolean;
}> {
// EIP-8161: Try SSZ-REST first, fall back to JSON-RPC on network errors
if (this.sszRestClient) {
try {
const version =
ForkSeq[fork] >= ForkSeq.fulu ? 5 : ForkSeq[fork] >= ForkSeq.electra ? 4 : ForkSeq[fork] >= ForkSeq.deneb ? 3 : ForkSeq[fork] >= ForkSeq.capella ? 2 : 1;
const path = `/engine/v${version}/payloads/${payloadId}`;
const resp = await this.sszRestClient.doGetRequest(path);
const decoded = decodeGetPayloadResponse(resp);

// The executionPayloadSsz needs to be parsed back through the JSON-RPC parseExecutionPayload path
// For now, we return the raw SSZ and let the caller handle it.
// Actually, we can deserialize the SSZ payload using @lodestar/types
const executionPayload = deserializeExecutionPayloadSsz(fork, decoded.executionPayloadSsz);
const executionPayloadValue = decoded.blockValue;
const blobsBundle =
decoded.blobsBundleSsz.length > 0 ? deserializeBlobsBundleSsz(decoded.blobsBundleSsz) : undefined;
const executionRequests =
decoded.executionRequestsSsz.length > 0
? deserializeExecutionRequestsSsz(decoded.executionRequestsSsz)
: undefined;
return {
executionPayload,
executionPayloadValue,
blobsBundle,
executionRequests,
shouldOverrideBuilder: decoded.shouldOverrideBuilder,
};
} catch (e) {
if (isSszRestNetworkError(e)) {
this.logger.debug("SSZ-REST getPayload failed, falling back to JSON-RPC", {error: (e as Error).message});
} else {
throw e;
}
}
}

let method: keyof EngineApiRpcReturnTypes;
switch (fork) {
case ForkName.phase0:
Expand Down Expand Up @@ -500,6 +658,28 @@ export class ExecutionEngineHttp implements IExecutionEngine {
versionedHashes: VersionedHashes
): Promise<BlobAndProofV2[] | (BlobAndProof | null)[] | null> {
assertReqSizeLimit(versionedHashes.length, MAX_VERSIONED_HASHES);

// EIP-8161: Try SSZ-REST first for getBlobs, fall back to JSON-RPC on network errors
if (this.sszRestClient) {
try {
const version = isForkPostFulu(fork) ? 2 : 1;
const path = `/engine/v${version}/blobs`;
const body = encodeGetBlobsRequest(versionedHashes);
const resp = await this.sszRestClient.doRequest(path, body);
const decoded = decodeGetBlobsResponse(resp);
return decoded.map((item) => ({
blob: item.blob,
proof: item.kzgProof,
}));
} catch (e) {
if (isSszRestNetworkError(e)) {
this.logger.debug("SSZ-REST getBlobs failed, falling back to JSON-RPC", {error: (e as Error).message});
} else {
throw e;
}
}
}

const versionedHashesHex = versionedHashes.map(bytesToData);
if (isForkPostFulu(fork)) {
return await this.getBlobsV2(versionedHashesHex);
Expand Down Expand Up @@ -629,6 +809,32 @@ export class ExecutionEngineHttp implements IExecutionEngine {
}
}

/**
* Deserialize an ExecutionPayload from SSZ bytes using the appropriate
* @lodestar/types codec for the given fork. Used by the SSZ-REST getPayload path.
*/
function deserializeExecutionPayloadSsz(fork: ForkName, data: Uint8Array): ExecutionPayload {
const forkSeq = ForkSeq[fork];
if (forkSeq >= ForkSeq.electra) {
return sszCodecs.electra.ExecutionPayload.deserialize(data);
}
if (forkSeq >= ForkSeq.deneb) {
return sszCodecs.deneb.ExecutionPayload.deserialize(data);
}
if (forkSeq >= ForkSeq.capella) {
return sszCodecs.capella.ExecutionPayload.deserialize(data);
}
return sszCodecs.bellatrix.ExecutionPayload.deserialize(data);
}

function deserializeBlobsBundleSsz(data: Uint8Array): BlobsBundle {
return sszCodecs.deneb.BlobsBundle.deserialize(data);
}

function deserializeExecutionRequestsSsz(data: Uint8Array): ExecutionRequests {
return sszCodecs.electra.ExecutionRequests.deserialize(data);
}

type EngineRequestKey = keyof EngineApiRpcParamTypes;
type EngineRequestByKey = {
[K in EngineRequestKey]: {method: K; params: EngineApiRpcParamTypes[K]; methodOpts: ReqOpts};
Expand Down
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