POST to eth/v1/builder/blinded_blocks missing header

[mcdee]

Description

When receiving a POST to /eth/v1/builder/blinded_blocks the spec says that we should obtain the version of the blinded block in the Eth-Consensus-Version, however this is not set by Lighthouse.

Version

lighthouse --version
Lighthouse v5.1.0-10a38a8
BLS library: blst-modern
SHA256 hardware acceleration: true
Allocator: jemalloc
Profile: maxperf
Specs: mainnet (true), minimal (false), gnosis (true)

Present Behaviour

No Eth-Consensus-Version header is set.

Expected Behaviour

An Eth-Consensus-Version header should be set as per https://ethereum.github.io/builder-specs/#/Builder/submitBlindedBlock

[michaelsproul]

How urgent is a fix here?

AFAIK we've never sent that header so this bug has existed since the builder API was defined 1.5 years ago

[michaelsproul]

Relevant section of the code is here for reference:

lighthouse/beacon_node/builder_client/src/lib.rs

Lines 140 to 163 in 2a3c709

	/// `POST /eth/v1/builder/blinded_blocks`
	pub async fn post_builder_blinded_blocks<E: EthSpec>(
	&self,
	blinded_block: &SignedBlindedBeaconBlock<E>,
	) -> Result<ForkVersionedResponse<FullPayloadContents<E>>, Error> {
	let mut path = self.server.full.clone();
	path.path_segments_mut()
	.map_err(|()| Error::InvalidUrl(self.server.clone()))?
	.push("eth")
	.push("v1")
	.push("builder")
	.push("blinded_blocks");
	Ok(self
	.post_with_raw_response(
	path,
	&blinded_block,
	Some(self.timeouts.post_blinded_blocks),
	)
	.await?
	.json()
	.await?)
	}

[mcdee]

It's not critical any time soon, but I do wonder how relays know the version of the block to decode without it. I'm trying to be a bit more "by the rules"; although at current I hard-code a missing consensus version to Deneb it isn't the most future-proof of solutions.

[eserilev]

closed in #5407