From 4908687e7d0b8b00dd6ecd3f7e646d952155a02f Mon Sep 17 00:00:00 2001 From: Michael Sproul Date: Mon, 3 Nov 2025 19:06:03 +1100 Subject: [PATCH] Proposer duties backwards compat (#8335) The beacon API spec wasn't updated to use the Fulu definition of `dependent_root` for the proposer duties endpoint. No other client updated their logic, so to retain backwards compatibility the decision has been made to continue using the block root at the end of epoch `N - 1`, and introduce a new v2 endpoint down the track to use the correct dependent root. Eth R&D discussion: https://discord.com/channels/595666850260713488/598292067260825641/1433036715848765562 Change the behaviour of the v1 endpoint back to using the last slot of `N - 1` rather than the last slot of `N - 2`. This introduces the possibility of dependent root false positives (the root can change without changing the shuffling), but causes the least compatibility issues with other clients. Co-Authored-By: Michael Sproul --- .../beacon_chain/src/beacon_proposer_cache.rs | 23 ++++++++++++++-- beacon_node/beacon_chain/tests/store_tests.rs | 9 ++++--- beacon_node/http_api/src/proposer_duties.rs | 27 +++++++++++++------ .../http_api/tests/interactive_tests.rs | 3 +-- consensus/types/src/beacon_state.rs | 16 +++++++++++ testing/ef_tests/src/cases/fork_choice.rs | 2 +- 6 files changed, 64 insertions(+), 16 deletions(-) diff --git a/beacon_node/beacon_chain/src/beacon_proposer_cache.rs b/beacon_node/beacon_chain/src/beacon_proposer_cache.rs index 6effce49f8..bd6460eba7 100644 --- a/beacon_node/beacon_chain/src/beacon_proposer_cache.rs +++ b/beacon_node/beacon_chain/src/beacon_proposer_cache.rs @@ -166,10 +166,17 @@ impl BeaconProposerCache { } /// Compute the proposer duties using the head state without cache. +/// +/// Return: +/// - Proposer indices. +/// - True dependent root. +/// - Legacy dependent root (last block of epoch `N - 1`). +/// - Head execution status. +/// - Fork at `request_epoch`. pub fn compute_proposer_duties_from_head( request_epoch: Epoch, chain: &BeaconChain, -) -> Result<(Vec, Hash256, ExecutionStatus, Fork), BeaconChainError> { +) -> Result<(Vec, Hash256, Hash256, ExecutionStatus, Fork), BeaconChainError> { // Atomically collect information about the head whilst holding the canonical head `Arc` as // short as possible. let (mut state, head_state_root, head_block_root) = { @@ -203,11 +210,23 @@ pub fn compute_proposer_duties_from_head( .proposer_shuffling_decision_root_at_epoch(request_epoch, head_block_root, &chain.spec) .map_err(BeaconChainError::from)?; + // This is only required because the V1 proposer duties endpoint spec wasn't updated for Fulu. We + // can delete this once the V1 endpoint is deprecated at the Glamsterdam fork. + let legacy_dependent_root = state + .legacy_proposer_shuffling_decision_root_at_epoch(request_epoch, head_block_root) + .map_err(BeaconChainError::from)?; + // Use fork_at_epoch rather than the state's fork, because post-Fulu we may not have advanced // the state completely into the new epoch. let fork = chain.spec.fork_at_epoch(request_epoch); - Ok((indices, dependent_root, execution_status, fork)) + Ok(( + indices, + dependent_root, + legacy_dependent_root, + execution_status, + fork, + )) } /// If required, advance `state` to the epoch required to determine proposer indices in `target_epoch`. diff --git a/beacon_node/beacon_chain/tests/store_tests.rs b/beacon_node/beacon_chain/tests/store_tests.rs index 7891b22432..0c83244f44 100644 --- a/beacon_node/beacon_chain/tests/store_tests.rs +++ b/beacon_node/beacon_chain/tests/store_tests.rs @@ -1561,7 +1561,7 @@ async fn proposer_duties_from_head_fulu() { // Compute the proposer duties at the next epoch from the head let next_epoch = head_state.next_epoch().unwrap(); - let (_indices, dependent_root, _, fork) = + let (_indices, dependent_root, legacy_dependent_root, _, fork) = compute_proposer_duties_from_head(next_epoch, &harness.chain).unwrap(); assert_eq!( @@ -1570,6 +1570,8 @@ async fn proposer_duties_from_head_fulu() { .proposer_shuffling_decision_root_at_epoch(next_epoch, head_block_root.into(), spec) .unwrap() ); + assert_ne!(dependent_root, legacy_dependent_root); + assert_eq!(legacy_dependent_root, Hash256::from(head_block_root)); assert_eq!(fork, head_state.fork()); } @@ -1617,7 +1619,7 @@ async fn proposer_lookahead_gloas_fork_epoch() { assert_eq!(head_state.current_epoch(), gloas_fork_epoch - 1); // Compute the proposer duties at the fork epoch from the head. - let (indices, dependent_root, _, fork) = + let (indices, dependent_root, legacy_dependent_root, _, fork) = compute_proposer_duties_from_head(gloas_fork_epoch, &harness.chain).unwrap(); assert_eq!( @@ -1630,6 +1632,7 @@ async fn proposer_lookahead_gloas_fork_epoch() { ) .unwrap() ); + assert_ne!(dependent_root, legacy_dependent_root); assert_ne!(fork, head_state.fork()); assert_eq!(fork, spec.fork_at_epoch(gloas_fork_epoch)); @@ -1639,7 +1642,7 @@ async fn proposer_lookahead_gloas_fork_epoch() { .add_attested_blocks_at_slots(head_state, head_state_root, &gloas_slots, &all_validators) .await; - let (no_lookahead_indices, no_lookahead_dependent_root, _, no_lookahead_fork) = + let (no_lookahead_indices, no_lookahead_dependent_root, _, _, no_lookahead_fork) = compute_proposer_duties_from_head(gloas_fork_epoch, &harness.chain).unwrap(); assert_eq!(no_lookahead_indices, indices); diff --git a/beacon_node/http_api/src/proposer_duties.rs b/beacon_node/http_api/src/proposer_duties.rs index 78f99c475c..1ebb174785 100644 --- a/beacon_node/http_api/src/proposer_duties.rs +++ b/beacon_node/http_api/src/proposer_duties.rs @@ -60,13 +60,13 @@ pub fn proposer_duties( .safe_add(1) .map_err(warp_utils::reject::arith_error)? { - let (proposers, dependent_root, execution_status, _fork) = + let (proposers, _dependent_root, legacy_dependent_root, execution_status, _fork) = compute_proposer_duties_from_head(request_epoch, chain) .map_err(warp_utils::reject::unhandled_error)?; convert_to_api_response( chain, request_epoch, - dependent_root, + legacy_dependent_root, execution_status.is_optimistic_or_invalid(), proposers, ) @@ -116,6 +116,11 @@ fn try_proposer_duties_from_cache( .beacon_state .proposer_shuffling_decision_root_at_epoch(request_epoch, head_block_root, &chain.spec) .map_err(warp_utils::reject::beacon_state_error)?; + let legacy_dependent_root = head + .snapshot + .beacon_state + .legacy_proposer_shuffling_decision_root_at_epoch(request_epoch, head_block_root) + .map_err(warp_utils::reject::beacon_state_error)?; let execution_optimistic = chain .is_optimistic_or_invalid_head_block(head_block) .map_err(warp_utils::reject::unhandled_error)?; @@ -129,7 +134,7 @@ fn try_proposer_duties_from_cache( convert_to_api_response( chain, request_epoch, - head_decision_root, + legacy_dependent_root, execution_optimistic, indices.to_vec(), ) @@ -151,7 +156,7 @@ fn compute_and_cache_proposer_duties( current_epoch: Epoch, chain: &BeaconChain, ) -> Result { - let (indices, dependent_root, execution_status, fork) = + let (indices, dependent_root, legacy_dependent_root, execution_status, fork) = compute_proposer_duties_from_head(current_epoch, chain) .map_err(warp_utils::reject::unhandled_error)?; @@ -166,7 +171,7 @@ fn compute_and_cache_proposer_duties( convert_to_api_response( chain, current_epoch, - dependent_root, + legacy_dependent_root, execution_status.is_optimistic_or_invalid(), indices, ) @@ -229,12 +234,18 @@ fn compute_historic_proposer_duties( // We can supply the genesis block root as the block root since we know that the only block that // decides its own root is the genesis block. - let dependent_root = state - .proposer_shuffling_decision_root(chain.genesis_block_root, &chain.spec) + let legacy_dependent_root = state + .legacy_proposer_shuffling_decision_root_at_epoch(epoch, chain.genesis_block_root) .map_err(BeaconChainError::from) .map_err(warp_utils::reject::unhandled_error)?; - convert_to_api_response(chain, epoch, dependent_root, execution_optimistic, indices) + convert_to_api_response( + chain, + epoch, + legacy_dependent_root, + execution_optimistic, + indices, + ) } /// Converts the internal representation of proposer duties into one that is compatible with the diff --git a/beacon_node/http_api/tests/interactive_tests.rs b/beacon_node/http_api/tests/interactive_tests.rs index 5b016a7de4..a9de737d65 100644 --- a/beacon_node/http_api/tests/interactive_tests.rs +++ b/beacon_node/http_api/tests/interactive_tests.rs @@ -1017,10 +1017,9 @@ async fn proposer_duties_with_gossip_tolerance() { assert_eq!( proposer_duties_tolerant_current_epoch.dependent_root, head_state - .proposer_shuffling_decision_root_at_epoch( + .legacy_proposer_shuffling_decision_root_at_epoch( tolerant_current_epoch, head_block_root, - spec ) .unwrap() ); diff --git a/consensus/types/src/beacon_state.rs b/consensus/types/src/beacon_state.rs index 1bd4927fe8..9c4e50dc61 100644 --- a/consensus/types/src/beacon_state.rs +++ b/consensus/types/src/beacon_state.rs @@ -911,6 +911,22 @@ impl BeaconState { } } + /// Returns the block root at the last slot of `epoch - 1`. + /// + /// This can be deleted after Glamsterdam and the removal of the v1 proposer duties endpoint. + pub fn legacy_proposer_shuffling_decision_root_at_epoch( + &self, + epoch: Epoch, + head_block_root: Hash256, + ) -> Result { + let decision_slot = epoch.saturating_sub(1u64).end_slot(E::slots_per_epoch()); + if self.slot() <= decision_slot { + Ok(head_block_root) + } else { + self.get_block_root(decision_slot).copied() + } + } + /// Returns the block root which decided the proposer shuffling for the current epoch. This root /// can be used to key this proposer shuffling. /// diff --git a/testing/ef_tests/src/cases/fork_choice.rs b/testing/ef_tests/src/cases/fork_choice.rs index 47b9902345..8e9d438a24 100644 --- a/testing/ef_tests/src/cases/fork_choice.rs +++ b/testing/ef_tests/src/cases/fork_choice.rs @@ -920,7 +920,7 @@ impl Tester { let cached_head = self.harness.chain.canonical_head.cached_head(); let next_slot = cached_head.snapshot.beacon_block.slot() + 1; let next_slot_epoch = next_slot.epoch(E::slots_per_epoch()); - let (proposer_indices, decision_root, _, fork) = + let (proposer_indices, decision_root, _, _, fork) = compute_proposer_duties_from_head(next_slot_epoch, &self.harness.chain).unwrap(); let proposer_index = proposer_indices[next_slot.as_usize() % E::slots_per_epoch() as usize];