Altair validator client and HTTP API (#2404)

## Proposed Changes

* Implement the validator client and HTTP API changes necessary to support Altair


Co-authored-by: realbigsean <seananderson33@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>

Cargo.lock

@@ -7312,6 +7312,7 @@ dependencies = [
  "futures",
  "hex",
  "hyper",
+ "itertools 0.10.1",
  "lazy_static",
  "libc",
  "libsecp256k1",

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -43,7 +43,7 @@ use crate::validator_pubkey_cache::ValidatorPubkeyCache;
 use crate::BeaconForkChoiceStore;
 use crate::BeaconSnapshot;
 use crate::{metrics, BeaconChainError};
-use eth2::types::{EventKind, SseBlock, SseChainReorg, SseFinalizedCheckpoint, SseHead};
+use eth2::types::{EventKind, SseBlock, SseChainReorg, SseFinalizedCheckpoint, SseHead, SyncDuty};
 use fork_choice::ForkChoice;
 use futures::channel::mpsc::Sender;
 use itertools::process_results;
@@ -1081,6 +1081,29 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         Ok(pubkey_cache.get_index(pubkey))
     }
 
+    /// Return the validator indices of all public keys fetched from an iterator.
+    ///
+    /// If any public key doesn't belong to a known validator then an error will be returned.
+    /// We could consider relaxing this by returning `Vec<Option<usize>>` in future.
+    pub fn validator_indices<'a>(
+        &self,
+        validator_pubkeys: impl Iterator<Item = &'a PublicKeyBytes>,
+    ) -> Result<Vec<u64>, Error> {
+        let pubkey_cache = self
+            .validator_pubkey_cache
+            .try_read_for(VALIDATOR_PUBKEY_CACHE_LOCK_TIMEOUT)
+            .ok_or(Error::ValidatorPubkeyCacheLockTimeout)?;
+
+        validator_pubkeys
+            .map(|pubkey| {
+                pubkey_cache
+                    .get_index(pubkey)
+                    .map(|id| id as u64)
+                    .ok_or(Error::ValidatorPubkeyUnknown(*pubkey))
+            })
+            .collect()
+    }
+
     /// Returns the validator pubkey (if any) for the given validator index.
     ///
     /// ## Notes
@@ -1214,6 +1237,16 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             .get_by_slot_and_root(slot, attestation_data_root)
     }
 
+    /// Return an aggregated `SyncCommitteeContribution` matching the given `root`.
+    pub fn get_aggregated_sync_committee_contribution(
+        &self,
+        sync_contribution_data: &SyncContributionData,
+    ) -> Option<SyncCommitteeContribution<T::EthSpec>> {
+        self.naive_sync_aggregation_pool
+            .read()
+            .get(sync_contribution_data)
+    }
+
     /// Produce an unaggregated `Attestation` that is valid for the given `slot` and `index`.
     ///
     /// The produced `Attestation` will not be valid until it has been signed by exactly one
@@ -1882,6 +1915,19 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         Ok(())
     }
 
+    /// Attempt to obtain sync committee duties from the head.
+    pub fn sync_committee_duties_from_head(
+        &self,
+        epoch: Epoch,
+        validator_indices: &[u64],
+    ) -> Result<Vec<Option<SyncDuty>>, Error> {
+        self.with_head(move |head| {
+            head.beacon_state
+                .get_sync_committee_duties(epoch, validator_indices, &self.spec)
+                .map_err(Error::SyncDutiesError)
+        })
+    }
+
     /// Attempt to verify and import a chain of blocks to `self`.
     ///
     /// The provided blocks _must_ each reference the previous block via `block.parent_root` (i.e.,
@@ -2624,6 +2670,22 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         let proposer_index = state.get_beacon_proposer_index(state.slot(), &self.spec)? as u64;
         let voluntary_exits = self.op_pool.get_voluntary_exits(&state, &self.spec).into();
 
+        // Closure to fetch a sync aggregate in cases where it is required.
+        let get_sync_aggregate = || -> Result<SyncAggregate<_>, BlockProductionError> {
+            Ok(self
+                .op_pool
+                .get_sync_aggregate(&state)
+                .map_err(BlockProductionError::OpPoolError)?
+                .unwrap_or_else(|| {
+                    warn!(
+                        self.log,
+                        "Producing block with no sync contributions";
+                        "slot" => state.slot(),
+                    );
+                    SyncAggregate::new()
+                }))
+        };
+
         let inner_block = match state {
             BeaconState::Base(_) => BeaconBlock::Base(BeaconBlockBase {
                 slot,
@@ -2641,24 +2703,26 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     voluntary_exits,
                 },
             }),
-            BeaconState::Altair(_) => BeaconBlock::Altair(BeaconBlockAltair {
-                slot,
-                proposer_index,
-                parent_root,
-                state_root: Hash256::zero(),
-                body: BeaconBlockBodyAltair {
-                    randao_reveal,
-                    eth1_data,
-                    graffiti,
-                    proposer_slashings: proposer_slashings.into(),
-                    attester_slashings: attester_slashings.into(),
-                    attestations,
-                    deposits,
-                    voluntary_exits,
-                    // FIXME(altair): put a sync aggregate from the pool here (once implemented)
-                    sync_aggregate: SyncAggregate::new(),
-                },
-            }),
+            BeaconState::Altair(_) => {
+                let sync_aggregate = get_sync_aggregate()?;
+                BeaconBlock::Altair(BeaconBlockAltair {
+                    slot,
+                    proposer_index,
+                    parent_root,
+                    state_root: Hash256::zero(),
+                    body: BeaconBlockBodyAltair {
+                        randao_reveal,
+                        eth1_data,
+                        graffiti,
+                        proposer_slashings: proposer_slashings.into(),
+                        attester_slashings: attester_slashings.into(),
+                        attestations,
+                        deposits,
+                        voluntary_exits,
+                        sync_aggregate,
+                    },
+                })
+            }
         };
 
         let block = SignedBeaconBlock::from_block(

beacon_node/beacon_chain/src/errors.rs

@@ -87,6 +87,7 @@ pub enum BeaconChainError {
     DuplicateValidatorPublicKey,
     ValidatorPubkeyCacheFileError(String),
     ValidatorIndexUnknown(usize),
+    ValidatorPubkeyUnknown(PublicKeyBytes),
     OpPoolError(OpPoolError),
     NaiveAggregationError(NaiveAggregationError),
     ObservedAttestationsError(ObservedAttestationsError),
@@ -120,6 +121,7 @@ pub enum BeaconChainError {
         state_epoch: Epoch,
         shuffling_epoch: Epoch,
     },
+    SyncDutiesError(BeaconStateError),
     InconsistentForwardsIter {
         request_slot: Slot,
         slot: Slot,

beacon_node/beacon_chain/src/test_utils.rs

@@ -151,7 +151,7 @@ pub fn test_spec<E: EthSpec>() -> ChainSpec {
 pub struct BeaconChainHarness<T: BeaconChainTypes> {
     pub validator_keypairs: Vec<Keypair>,
 
-    pub chain: BeaconChain<T>,
+    pub chain: Arc<BeaconChain<T>>,
     pub spec: ChainSpec,
     pub data_dir: TempDir,
     pub shutdown_receiver: Receiver<ShutdownReason>,
@@ -229,6 +229,29 @@ impl<E: EthSpec> BeaconChainHarness<EphemeralHarnessType<E>> {
         target_aggregators_per_committee: u64,
         store_config: StoreConfig,
         chain_config: ChainConfig,
+    ) -> Self {
+        Self::new_with_mutator(
+            eth_spec_instance,
+            spec,
+            validator_keypairs,
+            target_aggregators_per_committee,
+            store_config,
+            chain_config,
+            |x| x,
+        )
+    }
+
+    /// Apply a function to beacon chain builder before building.
+    pub fn new_with_mutator(
+        eth_spec_instance: E,
+        spec: Option<ChainSpec>,
+        validator_keypairs: Vec<Keypair>,
+        target_aggregators_per_committee: u64,
+        store_config: StoreConfig,
+        chain_config: ChainConfig,
+        mutator: impl FnOnce(
+            BeaconChainBuilder<EphemeralHarnessType<E>>,
+        ) -> BeaconChainBuilder<EphemeralHarnessType<E>>,
     ) -> Self {
         let data_dir = tempdir().expect("should create temporary data_dir");
         let mut spec = spec.unwrap_or_else(test_spec::<E>);
@@ -240,7 +263,7 @@ impl<E: EthSpec> BeaconChainHarness<EphemeralHarnessType<E>> {
         let log = test_logger();
 
         let store = HotColdDB::open_ephemeral(store_config, spec.clone(), log.clone()).unwrap();
-        let chain = BeaconChainBuilder::new(eth_spec_instance)
+        let builder = BeaconChainBuilder::new(eth_spec_instance)
             .logger(log.clone())
             .custom_spec(spec.clone())
             .store(Arc::new(store))
@@ -260,13 +283,13 @@ impl<E: EthSpec> BeaconChainHarness<EphemeralHarnessType<E>> {
                 log.clone(),
                 1,
             )))
-            .monitor_validators(true, vec![], log)
-            .build()
-            .expect("should build");
+            .monitor_validators(true, vec![], log);
+
+        let chain = mutator(builder).build().expect("should build");
 
         Self {
             spec: chain.spec.clone(),
-            chain,
+            chain: Arc::new(chain),
             validator_keypairs,
             data_dir,
             shutdown_receiver,
@@ -311,7 +334,7 @@ impl<E: EthSpec> BeaconChainHarness<DiskHarnessType<E>> {
 
         Self {
             spec: chain.spec.clone(),
-            chain,
+            chain: Arc::new(chain),
             validator_keypairs,
             data_dir,
             shutdown_receiver,
@@ -353,7 +376,7 @@ impl<E: EthSpec> BeaconChainHarness<DiskHarnessType<E>> {
 
         Self {
             spec: chain.spec.clone(),
-            chain,
+            chain: Arc::new(chain),
             validator_keypairs,
             data_dir,
             shutdown_receiver,

beacon_node/beacon_chain/tests/block_verification.rs

@@ -4,7 +4,7 @@
 extern crate lazy_static;
 
 use beacon_chain::test_utils::{
-    AttestationStrategy, BeaconChainHarness, BlockStrategy, EphemeralHarnessType,
+    test_logger, AttestationStrategy, BeaconChainHarness, BlockStrategy, EphemeralHarnessType,
 };
 use beacon_chain::{BeaconSnapshot, BlockError, ChainConfig, ChainSegmentResult};
 use slasher::{Config as SlasherConfig, Slasher};
@@ -830,17 +830,25 @@ fn block_gossip_verification() {
 
 #[test]
 fn verify_block_for_gossip_slashing_detection() {
-    let mut harness = get_harness(VALIDATOR_COUNT);
-
     let slasher_dir = tempdir().unwrap();
     let slasher = Arc::new(
         Slasher::open(
             SlasherConfig::new(slasher_dir.path().into()).for_testing(),
-            harness.logger().clone(),
+            test_logger(),
         )
         .unwrap(),
     );
-    harness.chain.slasher = Some(slasher.clone());
+
+    let harness = BeaconChainHarness::new_with_mutator(
+        MainnetEthSpec,
+        None,
+        KEYPAIRS.to_vec(),
+        1 << 32,
+        StoreConfig::default(),
+        ChainConfig::default(),
+        |builder| builder.slasher(slasher.clone()),
+    );
+    harness.advance_slot();
 
     let state = harness.get_current_state();
     let (block1, _) = harness.make_block(state.clone(), Slot::new(1));

beacon_node/http_api/Cargo.toml

@@ -3,6 +3,7 @@ name = "http_api"
 version = "0.1.0"
 authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"
+autotests = false # using a single test binary compiles faster
 
 [dependencies]
 warp = { git = "https://github.com/paulhauner/warp ", branch = "cors-wildcard" }
@@ -35,3 +36,7 @@ store = { path = "../store" }
 environment = { path = "../../lighthouse/environment" }
 tree_hash = "0.1.1"
 sensitive_url = { path = "../../common/sensitive_url" }
+
+[[test]]
+name = "bn_http_api_tests"
+path = "tests/main.rs"

beacon_node/http_api/src/lib.rs

@@ -10,7 +10,9 @@ mod block_id;
 mod metrics;
 mod proposer_duties;
 mod state_id;
+mod sync_committees;
 mod validator_inclusion;
+mod version;
 
 use beacon_chain::{
     attestation_verification::SignatureVerifiedAttestation,
@@ -20,7 +22,7 @@ use beacon_chain::{
     WhenSlotSkipped,
 };
 use block_id::BlockId;
-use eth2::types::{self as api_types, ValidatorId};
+use eth2::types::{self as api_types, EndpointVersion, ValidatorId};
 use eth2_libp2p::{types::SyncState, EnrExt, NetworkGlobals, PeerId, PubsubMessage};
 use lighthouse_version::version_with_platform;
 use network::NetworkMessage;
@@ -37,10 +39,12 @@ use std::sync::Arc;
 use tokio::sync::mpsc::UnboundedSender;
 use tokio_stream::{wrappers::BroadcastStream, StreamExt};
 use types::{
-    Attestation, AttesterSlashing, CommitteeCache, ConfigAndPreset, Epoch, EthSpec,
-    ProposerSlashing, RelativeEpoch, SignedAggregateAndProof, SignedBeaconBlock,
-    SignedVoluntaryExit, Slot,
+    Attestation, AttesterSlashing, BeaconStateError, CommitteeCache, ConfigAndPreset, Epoch,
+    EthSpec, ProposerSlashing, RelativeEpoch, SignedAggregateAndProof, SignedBeaconBlock,
+    SignedContributionAndProof, SignedVoluntaryExit, Slot, SyncCommitteeMessage,
+    SyncContributionData,
 };
+use version::{fork_versioned_response, unsupported_version_rejection, V1};
 use warp::http::StatusCode;
 use warp::sse::Event;
 use warp::Reply;
@@ -48,7 +52,6 @@ use warp::{http::Response, Filter};
 use warp_utils::task::{blocking_json_task, blocking_task};
 
 const API_PREFIX: &str = "eth";
-const API_VERSION: &str = "v1";
 
 /// If the node is within this many epochs from the head, we declare it to be synced regardless of
 /// the network sync state.
@@ -152,7 +155,7 @@ pub fn prometheus_metrics() -> warp::filters::log::Log<impl Fn(warp::filters::lo
         // a block hash).
         let path = {
             let equals = |s: &'static str| -> Option<&'static str> {
-                if info.path() == format!("/{}/{}/{}", API_PREFIX, API_VERSION, s) {
+                if info.path() == format!("/{}/{}", API_PREFIX, s) {
                     Some(s)
                 } else {
                     None
@@ -160,30 +163,30 @@ pub fn prometheus_metrics() -> warp::filters::log::Log<impl Fn(warp::filters::lo
             };
 
             let starts_with = |s: &'static str| -> Option<&'static str> {
-                if info
-                    .path()
-                    .starts_with(&format!("/{}/{}/{}", API_PREFIX, API_VERSION, s))
-                {
+                if info.path().starts_with(&format!("/{}/{}", API_PREFIX, s)) {
                     Some(s)
                 } else {
                     None
                 }
             };
 
-            equals("beacon/blocks")
-                .or_else(|| starts_with("validator/duties/attester"))
-                .or_else(|| starts_with("validator/duties/proposer"))
-                .or_else(|| starts_with("validator/attestation_data"))
-                .or_else(|| starts_with("validator/blocks"))
-                .or_else(|| starts_with("validator/aggregate_attestation"))
-                .or_else(|| starts_with("validator/aggregate_and_proofs"))
-                .or_else(|| starts_with("validator/beacon_committee_subscriptions"))
-                .or_else(|| starts_with("beacon/"))
-                .or_else(|| starts_with("config/"))
-                .or_else(|| starts_with("debug/"))
-                .or_else(|| starts_with("events/"))
-                .or_else(|| starts_with("node/"))
-                .or_else(|| starts_with("validator/"))
+            // First line covers `POST /v1/beacon/blocks` only
+            equals("v1/beacon/blocks")
+                .or_else(|| starts_with("v1/validator/duties/attester"))
+                .or_else(|| starts_with("v1/validator/duties/proposer"))
+                .or_else(|| starts_with("v1/validator/attestation_data"))
+                .or_else(|| starts_with("v1/validator/blocks"))
+                .or_else(|| starts_with("v2/validator/blocks"))
+                .or_else(|| starts_with("v1/validator/aggregate_attestation"))
+                .or_else(|| starts_with("v1/validator/aggregate_and_proofs"))
+                .or_else(|| starts_with("v1/validator/beacon_committee_subscriptions"))
+                .or_else(|| starts_with("v1/beacon/"))
+                .or_else(|| starts_with("v2/beacon/"))
+                .or_else(|| starts_with("v1/config/"))
+                .or_else(|| starts_with("v1/debug/"))
+                .or_else(|| starts_with("v1/events/"))
+                .or_else(|| starts_with("v1/node/"))
+                .or_else(|| starts_with("v1/validator/"))
                 .unwrap_or("other")
         };
 
@@ -239,7 +242,29 @@ pub fn serve<T: BeaconChainTypes>(
         ));
     }
 
-    let eth1_v1 = warp::path(API_PREFIX).and(warp::path(API_VERSION));
+    // Create a filter that extracts the endpoint version.
+    let any_version = warp::path(API_PREFIX).and(warp::path::param::<EndpointVersion>().or_else(
+        |_| async move {
+            Err(warp_utils::reject::custom_bad_request(
+                "Invalid version identifier".to_string(),
+            ))
+        },
+    ));
+
+    // Filter that enforces a single endpoint version and then discards the `EndpointVersion`.
+    let single_version = |reqd: EndpointVersion| {
+        any_version
+            .and_then(move |version| async move {
+                if version == reqd {
+                    Ok(())
+                } else {
+                    Err(unsupported_version_rejection(version))
+                }
+            })
+            .untuple_one()
+    };
+
+    let eth1_v1 = single_version(V1);
 
     // Create a `warp` filter that provides access to the network globals.
     let inner_network_globals = ctx.network_globals.clone();
@@ -659,6 +684,61 @@ pub fn serve<T: BeaconChainTypes>(
             },
         );
 
+    // GET beacon/states/{state_id}/sync_committees?epoch
+    let get_beacon_state_sync_committees = beacon_states_path
+        .clone()
+        .and(warp::path("sync_committees"))
+        .and(warp::query::<api_types::SyncCommitteesQuery>())
+        .and(warp::path::end())
+        .and_then(
+            |state_id: StateId,
+             chain: Arc<BeaconChain<T>>,
+             query: api_types::SyncCommitteesQuery| {
+                blocking_json_task(move || {
+                    let sync_committee = state_id.map_state(&chain, |state| {
+                        let current_epoch = state.current_epoch();
+                        let epoch = query.epoch.unwrap_or(current_epoch);
+                        state
+                            .get_built_sync_committee(epoch, &chain.spec)
+                            .map(|committee| committee.clone())
+                            .map_err(|e| match e {
+                                BeaconStateError::SyncCommitteeNotKnown { .. } => {
+                                    warp_utils::reject::custom_bad_request(format!(
+                                        "state at epoch {} has no sync committee for epoch {}",
+                                        current_epoch, epoch
+                                    ))
+                                }
+                                BeaconStateError::IncorrectStateVariant => {
+                                    warp_utils::reject::custom_bad_request(format!(
+                                        "state at epoch {} is not activated for Altair",
+                                        current_epoch,
+                                    ))
+                                }
+                                e => warp_utils::reject::beacon_state_error(e),
+                            })
+                    })?;
+
+                    let validators = chain
+                        .validator_indices(sync_committee.pubkeys.iter())
+                        .map_err(warp_utils::reject::beacon_chain_error)?;
+
+                    let validator_aggregates = validators
+                        .chunks_exact(T::EthSpec::sync_subcommittee_size())
+                        .map(|indices| api_types::SyncSubcommittee {
+                            indices: indices.to_vec(),
+                        })
+                        .collect();
+
+                    let response = api_types::SyncCommitteeByValidatorIndices {
+                        validators,
+                        validator_aggregates,
+                    };
+
+                    Ok(api_types::GenericResponse::from(response))
+                })
+            },
+        );
+
     // GET beacon/headers
     //
     // Note: this endpoint only returns information about blocks in the canonical chain. Given that
@@ -875,23 +955,32 @@ pub fn serve<T: BeaconChainTypes>(
             },
         );
 
-    let beacon_blocks_path = eth1_v1
+    let block_id_or_err = warp::path::param::<BlockId>().or_else(|_| async {
+        Err(warp_utils::reject::custom_bad_request(
+            "Invalid block ID".to_string(),
+        ))
+    });
+
+    let beacon_blocks_path_v1 = eth1_v1
         .and(warp::path("beacon"))
         .and(warp::path("blocks"))
-        .and(warp::path::param::<BlockId>().or_else(|_| async {
-            Err(warp_utils::reject::custom_bad_request(
-                "Invalid block ID".to_string(),
-            ))
-        }))
+        .and(block_id_or_err)
+        .and(chain_filter.clone());
+
+    let beacon_blocks_path_any = any_version
+        .and(warp::path("beacon"))
+        .and(warp::path("blocks"))
+        .and(block_id_or_err)
         .and(chain_filter.clone());
 
     // GET beacon/blocks/{block_id}
-    let get_beacon_block = beacon_blocks_path
+    let get_beacon_block = beacon_blocks_path_any
         .clone()
         .and(warp::path::end())
         .and(warp::header::optional::<api_types::Accept>("accept"))
         .and_then(
-            |block_id: BlockId,
+            |endpoint_version: EndpointVersion,
+             block_id: BlockId,
              chain: Arc<BeaconChain<T>>,
              accept_header: Option<api_types::Accept>| {
                 blocking_task(move || {
@@ -907,17 +996,18 @@ pub fn serve<T: BeaconChainTypes>(
                                     e
                                 ))
                             }),
-                        _ => Ok(
-                            warp::reply::json(&api_types::GenericResponseRef::from(&block))
-                                .into_response(),
-                        ),
+                        _ => {
+                            let fork_name = block.fork_name(&chain.spec).ok();
+                            fork_versioned_response(endpoint_version, fork_name, block)
+                                .map(|res| warp::reply::json(&res).into_response())
+                        }
                     }
                 })
             },
         );
 
     // GET beacon/blocks/{block_id}/root
-    let get_beacon_block_root = beacon_blocks_path
+    let get_beacon_block_root = beacon_blocks_path_v1
         .clone()
         .and(warp::path("root"))
         .and(warp::path::end())
@@ -931,7 +1021,7 @@ pub fn serve<T: BeaconChainTypes>(
         });
 
     // GET beacon/blocks/{block_id}/attestations
-    let get_beacon_block_attestations = beacon_blocks_path
+    let get_beacon_block_attestations = beacon_blocks_path_v1
         .clone()
         .and(warp::path("attestations"))
         .and(warp::path::end())
@@ -1250,6 +1340,28 @@ pub fn serve<T: BeaconChainTypes>(
             })
         });
 
+    // POST beacon/pool/sync_committees
+    let post_beacon_pool_sync_committees = beacon_pool_path
+        .clone()
+        .and(warp::path("sync_committees"))
+        .and(warp::path::end())
+        .and(warp::body::json())
+        .and(network_tx_filter.clone())
+        .and(log_filter.clone())
+        .and_then(
+            |chain: Arc<BeaconChain<T>>,
+             signatures: Vec<SyncCommitteeMessage>,
+             network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
+             log: Logger| {
+                blocking_json_task(move || {
+                    sync_committees::process_sync_committee_signatures(
+                        signatures, network_tx, &chain, log,
+                    )?;
+                    Ok(api_types::GenericResponse::from(()))
+                })
+            },
+        );
+
     /*
      * config/fork_schedule
      */
@@ -1307,7 +1419,7 @@ pub fn serve<T: BeaconChainTypes>(
      */
 
     // GET debug/beacon/states/{state_id}
-    let get_debug_beacon_states = eth1_v1
+    let get_debug_beacon_states = any_version
         .and(warp::path("debug"))
         .and(warp::path("beacon"))
         .and(warp::path("states"))
@@ -1320,7 +1432,8 @@ pub fn serve<T: BeaconChainTypes>(
         .and(warp::header::optional::<api_types::Accept>("accept"))
         .and(chain_filter.clone())
         .and_then(
-            |state_id: StateId,
+            |endpoint_version: EndpointVersion,
+             state_id: StateId,
              accept_header: Option<api_types::Accept>,
              chain: Arc<BeaconChain<T>>| {
                 blocking_task(move || match accept_header {
@@ -1338,10 +1451,9 @@ pub fn serve<T: BeaconChainTypes>(
                             })
                     }
                     _ => state_id.map_state(&chain, |state| {
-                        Ok(
-                            warp::reply::json(&api_types::GenericResponseRef::from(&state))
-                                .into_response(),
-                        )
+                        let fork_name = state.fork_name(&chain.spec).ok();
+                        let res = fork_versioned_response(endpoint_version, fork_name, &state)?;
+                        Ok(warp::reply::json(&res).into_response())
                     }),
                 })
             },
@@ -1659,7 +1771,7 @@ pub fn serve<T: BeaconChainTypes>(
         });
 
     // GET validator/blocks/{slot}
-    let get_validator_blocks = eth1_v1
+    let get_validator_blocks = any_version
         .and(warp::path("validator"))
         .and(warp::path("blocks"))
         .and(warp::path::param::<Slot>().or_else(|_| async {
@@ -1672,7 +1784,10 @@ pub fn serve<T: BeaconChainTypes>(
         .and(warp::query::<api_types::ValidatorBlocksQuery>())
         .and(chain_filter.clone())
         .and_then(
-            |slot: Slot, query: api_types::ValidatorBlocksQuery, chain: Arc<BeaconChain<T>>| {
+            |endpoint_version: EndpointVersion,
+             slot: Slot,
+             query: api_types::ValidatorBlocksQuery,
+             chain: Arc<BeaconChain<T>>| {
                 blocking_json_task(move || {
                     let randao_reveal = (&query.randao_reveal).try_into().map_err(|e| {
                         warp_utils::reject::custom_bad_request(format!(
@@ -1681,11 +1796,11 @@ pub fn serve<T: BeaconChainTypes>(
                         ))
                     })?;
 
-                    chain
+                    let (block, _) = chain
                         .produce_block(randao_reveal, slot, query.graffiti.map(Into::into))
-                        .map(|block_and_state| block_and_state.0)
-                        .map(api_types::GenericResponse::from)
-                        .map_err(warp_utils::reject::block_production_error)
+                        .map_err(warp_utils::reject::block_production_error)?;
+                    let fork_name = block.to_ref().fork_name(&chain.spec).ok();
+                    fork_versioned_response(endpoint_version, fork_name, block)
                 })
             },
         );
@@ -1770,12 +1885,57 @@ pub fn serve<T: BeaconChainTypes>(
             },
         );
 
+    // POST validator/duties/sync
+    let post_validator_duties_sync = eth1_v1
+        .and(warp::path("validator"))
+        .and(warp::path("duties"))
+        .and(warp::path("sync"))
+        .and(warp::path::param::<Epoch>().or_else(|_| async {
+            Err(warp_utils::reject::custom_bad_request(
+                "Invalid epoch".to_string(),
+            ))
+        }))
+        .and(warp::path::end())
+        .and(not_while_syncing_filter.clone())
+        .and(warp::body::json())
+        .and(chain_filter.clone())
+        .and_then(
+            |epoch: Epoch, indices: api_types::ValidatorIndexData, chain: Arc<BeaconChain<T>>| {
+                blocking_json_task(move || {
+                    sync_committees::sync_committee_duties(epoch, &indices.0, &chain)
+                })
+            },
+        );
+
+    // GET validator/sync_committee_contribution
+    let get_validator_sync_committee_contribution = eth1_v1
+        .and(warp::path("validator"))
+        .and(warp::path("sync_committee_contribution"))
+        .and(warp::path::end())
+        .and(warp::query::<SyncContributionData>())
+        .and(not_while_syncing_filter.clone())
+        .and(chain_filter.clone())
+        .and_then(
+            |sync_committee_data: SyncContributionData, chain: Arc<BeaconChain<T>>| {
+                blocking_json_task(move || {
+                    chain
+                        .get_aggregated_sync_committee_contribution(&sync_committee_data)
+                        .map(api_types::GenericResponse::from)
+                        .ok_or_else(|| {
+                            warp_utils::reject::custom_not_found(
+                                "no matching sync contribution found".to_string(),
+                            )
+                        })
+                })
+            },
+        );
+
     // POST validator/aggregate_and_proofs
     let post_validator_aggregate_and_proofs = eth1_v1
         .and(warp::path("validator"))
         .and(warp::path("aggregate_and_proofs"))
         .and(warp::path::end())
-        .and(not_while_syncing_filter)
+        .and(not_while_syncing_filter.clone())
         .and(chain_filter.clone())
         .and(warp::body::json())
         .and(network_tx_filter.clone())
@@ -1871,13 +2031,39 @@ pub fn serve<T: BeaconChainTypes>(
             },
         );
 
+    let post_validator_contribution_and_proofs = eth1_v1
+        .and(warp::path("validator"))
+        .and(warp::path("contribution_and_proofs"))
+        .and(warp::path::end())
+        .and(not_while_syncing_filter)
+        .and(chain_filter.clone())
+        .and(warp::body::json())
+        .and(network_tx_filter.clone())
+        .and(log_filter.clone())
+        .and_then(
+            |chain: Arc<BeaconChain<T>>,
+             contributions: Vec<SignedContributionAndProof<T::EthSpec>>,
+             network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
+             log: Logger| {
+                blocking_json_task(move || {
+                    sync_committees::process_signed_contribution_and_proofs(
+                        contributions,
+                        network_tx,
+                        &chain,
+                        log,
+                    )?;
+                    Ok(api_types::GenericResponse::from(()))
+                })
+            },
+        );
+
     // POST validator/beacon_committee_subscriptions
     let post_validator_beacon_committee_subscriptions = eth1_v1
         .and(warp::path("validator"))
         .and(warp::path("beacon_committee_subscriptions"))
         .and(warp::path::end())
         .and(warp::body::json())
-        .and(network_tx_filter)
+        .and(network_tx_filter.clone())
         .and(chain_filter.clone())
         .and_then(
             |subscriptions: Vec<api_types::BeaconCommitteeSubscription>,
@@ -1911,6 +2097,38 @@ pub fn serve<T: BeaconChainTypes>(
             },
         );
 
+    // POST validator/sync_committee_subscriptions
+    let post_validator_sync_committee_subscriptions = eth1_v1
+        .and(warp::path("validator"))
+        .and(warp::path("sync_committee_subscriptions"))
+        .and(warp::path::end())
+        .and(warp::body::json())
+        .and(network_tx_filter)
+        .and(chain_filter.clone())
+        .and_then(
+            |subscriptions: Vec<types::SyncCommitteeSubscription>,
+             network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
+             chain: Arc<BeaconChain<T>>| {
+                blocking_json_task(move || {
+                    for subscription in subscriptions {
+                        chain
+                            .validator_monitor
+                            .write()
+                            .auto_register_local_validator(subscription.validator_index);
+
+                        publish_network_message(
+                            &network_tx,
+                            NetworkMessage::SyncCommitteeSubscribe {
+                                subscriptions: vec![subscription],
+                            },
+                        )?;
+                    }
+
+                    Ok(())
+                })
+            },
+        );
+
     // POST lighthouse/liveness
     let post_lighthouse_liveness = warp::path("lighthouse")
         .and(warp::path("liveness"))
@@ -2248,6 +2466,7 @@ pub fn serve<T: BeaconChainTypes>(
                 .or(get_beacon_state_validators.boxed())
                 .or(get_beacon_state_validators_id.boxed())
                 .or(get_beacon_state_committees.boxed())
+                .or(get_beacon_state_sync_committees.boxed())
                 .or(get_beacon_headers.boxed())
                 .or(get_beacon_headers_block_id.boxed())
                 .or(get_beacon_block.boxed())
@@ -2273,6 +2492,7 @@ pub fn serve<T: BeaconChainTypes>(
                 .or(get_validator_blocks.boxed())
                 .or(get_validator_attestation_data.boxed())
                 .or(get_validator_aggregate_attestation.boxed())
+                .or(get_validator_sync_committee_contribution.boxed())
                 .or(get_lighthouse_health.boxed())
                 .or(get_lighthouse_syncing.boxed())
                 .or(get_lighthouse_peers.boxed())
@@ -2294,10 +2514,14 @@ pub fn serve<T: BeaconChainTypes>(
                 .or(post_beacon_pool_attester_slashings.boxed())
                 .or(post_beacon_pool_proposer_slashings.boxed())
                 .or(post_beacon_pool_voluntary_exits.boxed())
+                .or(post_beacon_pool_sync_committees.boxed())
                 .or(post_validator_duties_attester.boxed())
+                .or(post_validator_duties_sync.boxed())
                 .or(post_validator_aggregate_and_proofs.boxed())
-                .or(post_lighthouse_liveness.boxed())
-                .or(post_validator_beacon_committee_subscriptions.boxed()),
+                .or(post_validator_contribution_and_proofs.boxed())
+                .or(post_validator_beacon_committee_subscriptions.boxed())
+                .or(post_validator_sync_committee_subscriptions.boxed())
+                .or(post_lighthouse_liveness.boxed()),
         ))
         .recover(warp_utils::reject::handle_rejection)
         .with(slog_logging(log.clone()))

beacon_node/http_api/src/sync_committees.rs

@@ -0,0 +1,294 @@
+//! Handlers for sync committee endpoints.
+
+use crate::publish_pubsub_message;
+use beacon_chain::sync_committee_verification::{
+    Error as SyncVerificationError, VerifiedSyncCommitteeMessage,
+};
+use beacon_chain::{
+    BeaconChain, BeaconChainError, BeaconChainTypes, StateSkipConfig,
+    MAXIMUM_GOSSIP_CLOCK_DISPARITY,
+};
+use eth2::types::{self as api_types};
+use eth2_libp2p::PubsubMessage;
+use network::NetworkMessage;
+use slog::{error, warn, Logger};
+use slot_clock::SlotClock;
+use std::cmp::max;
+use std::collections::HashMap;
+use tokio::sync::mpsc::UnboundedSender;
+use types::{
+    slot_data::SlotData, BeaconStateError, Epoch, EthSpec, SignedContributionAndProof,
+    SyncCommitteeMessage, SyncDuty, SyncSubnetId,
+};
+
+/// The struct that is returned to the requesting HTTP client.
+type SyncDuties = api_types::GenericResponse<Vec<SyncDuty>>;
+
+/// Handles a request from the HTTP API for sync committee duties.
+pub fn sync_committee_duties<T: BeaconChainTypes>(
+    request_epoch: Epoch,
+    request_indices: &[u64],
+    chain: &BeaconChain<T>,
+) -> Result<SyncDuties, warp::reject::Rejection> {
+    let altair_fork_epoch = if let Some(altair_fork_epoch) = chain.spec.altair_fork_epoch {
+        altair_fork_epoch
+    } else {
+        // Empty response for networks with Altair disabled.
+        return Ok(convert_to_response(vec![]));
+    };
+
+    // Try using the head's sync committees to satisfy the request. This should be sufficient for
+    // the vast majority of requests. Rather than checking if we think the request will succeed in a
+    // way prone to data races, we attempt the request immediately and check the error code.
+    match chain.sync_committee_duties_from_head(request_epoch, request_indices) {
+        Ok(duties) => return Ok(convert_to_response(duties)),
+        Err(BeaconChainError::SyncDutiesError(BeaconStateError::SyncCommitteeNotKnown {
+            ..
+        }))
+        | Err(BeaconChainError::SyncDutiesError(BeaconStateError::IncorrectStateVariant)) => (),
+        Err(e) => return Err(warp_utils::reject::beacon_chain_error(e)),
+    }
+
+    let duties = duties_from_state_load(request_epoch, request_indices, altair_fork_epoch, chain)
+        .map_err(|e| match e {
+        BeaconChainError::SyncDutiesError(BeaconStateError::SyncCommitteeNotKnown {
+            current_epoch,
+            ..
+        }) => warp_utils::reject::custom_bad_request(format!(
+            "invalid epoch: {}, current epoch: {}",
+            request_epoch, current_epoch
+        )),
+        e => warp_utils::reject::beacon_chain_error(e),
+    })?;
+    Ok(convert_to_response(duties))
+}
+
+/// Slow path for duties: load a state and use it to compute the duties.
+fn duties_from_state_load<T: BeaconChainTypes>(
+    request_epoch: Epoch,
+    request_indices: &[u64],
+    altair_fork_epoch: Epoch,
+    chain: &BeaconChain<T>,
+) -> Result<Vec<Option<SyncDuty>>, BeaconChainError> {
+    // Determine what the current epoch would be if we fast-forward our system clock by
+    // `MAXIMUM_GOSSIP_CLOCK_DISPARITY`.
+    //
+    // Most of the time, `tolerant_current_epoch` will be equal to `current_epoch`. However, during
+    // the last `MAXIMUM_GOSSIP_CLOCK_DISPARITY` duration of the epoch `tolerant_current_epoch`
+    // will equal `current_epoch + 1`
+    let current_epoch = chain.epoch()?;
+    let tolerant_current_epoch = chain
+        .slot_clock
+        .now_with_future_tolerance(MAXIMUM_GOSSIP_CLOCK_DISPARITY)
+        .ok_or(BeaconChainError::UnableToReadSlot)?
+        .epoch(T::EthSpec::slots_per_epoch());
+
+    let max_sync_committee_period = tolerant_current_epoch.sync_committee_period(&chain.spec)? + 1;
+    let sync_committee_period = request_epoch.sync_committee_period(&chain.spec)?;
+
+    if tolerant_current_epoch < altair_fork_epoch {
+        // Empty response if the epoch is pre-Altair.
+        Ok(vec![])
+    } else if sync_committee_period <= max_sync_committee_period {
+        // Load the state at the start of the *previous* sync committee period.
+        // This is sufficient for historical duties, and efficient in the case where the head
+        // is lagging the current epoch and we need duties for the next period (because we only
+        // have to transition the head to start of the current period).
+        //
+        // We also need to ensure that the load slot is after the Altair fork.
+        let load_slot = max(
+            chain.spec.epochs_per_sync_committee_period * sync_committee_period.saturating_sub(1),
+            altair_fork_epoch,
+        )
+        .start_slot(T::EthSpec::slots_per_epoch());
+
+        let state = chain.state_at_slot(load_slot, StateSkipConfig::WithoutStateRoots)?;
+
+        state
+            .get_sync_committee_duties(request_epoch, request_indices, &chain.spec)
+            .map_err(BeaconChainError::SyncDutiesError)
+    } else {
+        Err(BeaconChainError::SyncDutiesError(
+            BeaconStateError::SyncCommitteeNotKnown {
+                current_epoch,
+                epoch: request_epoch,
+            },
+        ))
+    }
+}
+
+fn convert_to_response(duties: Vec<Option<SyncDuty>>) -> SyncDuties {
+    api_types::GenericResponse::from(duties.into_iter().flatten().collect::<Vec<_>>())
+}
+
+/// Receive sync committee duties, storing them in the pools & broadcasting them.
+pub fn process_sync_committee_signatures<T: BeaconChainTypes>(
+    sync_committee_signatures: Vec<SyncCommitteeMessage>,
+    network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
+    chain: &BeaconChain<T>,
+    log: Logger,
+) -> Result<(), warp::reject::Rejection> {
+    let mut failures = vec![];
+
+    for (i, sync_committee_signature) in sync_committee_signatures.iter().enumerate() {
+        let subnet_positions = match get_subnet_positions_for_sync_committee_message(
+            sync_committee_signature,
+            chain,
+        ) {
+            Ok(positions) => positions,
+            Err(e) => {
+                error!(
+                    log,
+                    "Unable to compute subnet positions for sync message";
+                    "error" => ?e,
+                    "slot" => sync_committee_signature.slot,
+                );
+                failures.push(api_types::Failure::new(i, format!("Verification: {:?}", e)));
+                continue;
+            }
+        };
+
+        // Verify and publish on all relevant subnets.
+        //
+        // The number of assigned subnets on any practical network should be ~1, so the apparent
+        // inefficiency of verifying multiple times is not a real inefficiency.
+        let mut verified_for_pool = None;
+        for subnet_id in subnet_positions.keys().copied() {
+            match VerifiedSyncCommitteeMessage::verify(
+                sync_committee_signature.clone(),
+                subnet_id,
+                chain,
+            ) {
+                Ok(verified) => {
+                    publish_pubsub_message(
+                        &network_tx,
+                        PubsubMessage::SyncCommitteeMessage(Box::new((
+                            subnet_id,
+                            verified.sync_message().clone(),
+                        ))),
+                    )?;
+
+                    verified_for_pool = Some(verified);
+                }
+                Err(e) => {
+                    error!(
+                        log,
+                        "Failure verifying sync committee signature for gossip";
+                        "error" => ?e,
+                        "request_index" => i,
+                        "slot" => sync_committee_signature.slot,
+                        "validator_index" => sync_committee_signature.validator_index,
+                    );
+                    failures.push(api_types::Failure::new(i, format!("Verification: {:?}", e)));
+                }
+            }
+        }
+
+        if let Some(verified) = verified_for_pool {
+            if let Err(e) = chain.add_to_naive_sync_aggregation_pool(verified) {
+                error!(
+                    log,
+                    "Unable to add sync committee signature to pool";
+                    "error" => ?e,
+                    "slot" => sync_committee_signature.slot,
+                    "validator_index" => sync_committee_signature.validator_index,
+                );
+            }
+        }
+    }
+
+    if failures.is_empty() {
+        Ok(())
+    } else {
+        Err(warp_utils::reject::indexed_bad_request(
+            "error processing sync committee signatures".to_string(),
+            failures,
+        ))
+    }
+}
+
+/// Get the set of all subnet assignments for a `SyncCommitteeMessage`.
+pub fn get_subnet_positions_for_sync_committee_message<T: BeaconChainTypes>(
+    sync_message: &SyncCommitteeMessage,
+    chain: &BeaconChain<T>,
+) -> Result<HashMap<SyncSubnetId, Vec<usize>>, SyncVerificationError> {
+    let pubkey = chain
+        .validator_pubkey_bytes(sync_message.validator_index as usize)?
+        .ok_or(SyncVerificationError::UnknownValidatorIndex(
+            sync_message.validator_index as usize,
+        ))?;
+    let sync_committee = chain.sync_committee_at_next_slot(sync_message.get_slot())?;
+    Ok(sync_committee.subcommittee_positions_for_public_key(&pubkey)?)
+}
+
+/// Receive signed contributions and proofs, storing them in the op pool and broadcasting.
+pub fn process_signed_contribution_and_proofs<T: BeaconChainTypes>(
+    signed_contribution_and_proofs: Vec<SignedContributionAndProof<T::EthSpec>>,
+    network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
+    chain: &BeaconChain<T>,
+    log: Logger,
+) -> Result<(), warp::reject::Rejection> {
+    let mut verified_contributions = Vec::with_capacity(signed_contribution_and_proofs.len());
+    let mut failures = vec![];
+
+    // Verify contributions & broadcast to the network.
+    for (index, contribution) in signed_contribution_and_proofs.into_iter().enumerate() {
+        let aggregator_index = contribution.message.aggregator_index;
+        let subcommittee_index = contribution.message.contribution.subcommittee_index;
+        let contribution_slot = contribution.message.contribution.slot;
+
+        match chain.verify_sync_contribution_for_gossip(contribution) {
+            Ok(verified_contribution) => {
+                publish_pubsub_message(
+                    &network_tx,
+                    PubsubMessage::SignedContributionAndProof(Box::new(
+                        verified_contribution.aggregate().clone(),
+                    )),
+                )?;
+
+                // FIXME(altair): notify validator monitor
+                verified_contributions.push((index, verified_contribution));
+            }
+            // If we already know the contribution, don't broadcast it or attempt to
+            // further verify it. Return success.
+            Err(SyncVerificationError::SyncContributionAlreadyKnown(_)) => continue,
+            Err(e) => {
+                error!(
+                    log,
+                    "Failure verifying signed contribution and proof";
+                    "error" => ?e,
+                    "request_index" => index,
+                    "aggregator_index" => aggregator_index,
+                    "subcommittee_index" => subcommittee_index,
+                    "contribution_slot" => contribution_slot,
+                );
+                failures.push(api_types::Failure::new(
+                    index,
+                    format!("Verification: {:?}", e),
+                ));
+            }
+        }
+    }
+
+    // Add to the block inclusion pool.
+    for (index, verified_contribution) in verified_contributions {
+        if let Err(e) = chain.add_contribution_to_block_inclusion_pool(verified_contribution) {
+            warn!(
+                log,
+                "Could not add verified sync contribution to the inclusion pool";
+                "error" => ?e,
+                "request_index" => index,
+            );
+            failures.push(api_types::Failure::new(index, format!("Op pool: {:?}", e)));
+        }
+    }
+
+    if !failures.is_empty() {
+        Err(warp_utils::reject::indexed_bad_request(
+            "error processing contribution and proofs".to_string(),
+            failures,
+        ))
+    } else {
+        Ok(())
+    }
+}

beacon_node/http_api/src/version.rs

@@ -0,0 +1,28 @@
+use crate::api_types::{EndpointVersion, ForkVersionedResponse};
+use serde::Serialize;
+use types::ForkName;
+
+pub const V1: EndpointVersion = EndpointVersion(1);
+pub const V2: EndpointVersion = EndpointVersion(2);
+
+pub fn fork_versioned_response<T: Serialize>(
+    endpoint_version: EndpointVersion,
+    fork_name: Option<ForkName>,
+    data: T,
+) -> Result<ForkVersionedResponse<T>, warp::reject::Rejection> {
+    let fork_name = if endpoint_version == V1 {
+        None
+    } else if endpoint_version == V2 {
+        fork_name
+    } else {
+        return Err(unsupported_version_rejection(endpoint_version));
+    };
+    Ok(ForkVersionedResponse {
+        version: fork_name,
+        data,
+    })
+}
+
+pub fn unsupported_version_rejection(version: EndpointVersion) -> warp::reject::Rejection {
+    warp_utils::reject::custom_bad_request(format!("Unsupported endpoint version: {}", version))
+}

beacon_node/http_api/tests/common.rs

@@ -0,0 +1,142 @@
+use beacon_chain::{
+    test_utils::{BeaconChainHarness, EphemeralHarnessType},
+    BeaconChain, BeaconChainTypes,
+};
+use eth2::{BeaconNodeHttpClient, Timeouts};
+use eth2_libp2p::{
+    discv5::enr::{CombinedKey, EnrBuilder},
+    rpc::methods::{MetaData, MetaDataV2},
+    types::{EnrAttestationBitfield, EnrSyncCommitteeBitfield, SyncState},
+    Enr, NetworkGlobals, PeerId,
+};
+use http_api::{Config, Context};
+use network::NetworkMessage;
+use sensitive_url::SensitiveUrl;
+use slog::Logger;
+use std::future::Future;
+use std::net::{Ipv4Addr, SocketAddr};
+use std::sync::Arc;
+use std::time::Duration;
+use tokio::sync::{mpsc, oneshot};
+use types::{test_utils::generate_deterministic_keypairs, ChainSpec, EthSpec};
+
+pub const TCP_PORT: u16 = 42;
+pub const UDP_PORT: u16 = 42;
+pub const SEQ_NUMBER: u64 = 0;
+pub const EXTERNAL_ADDR: &str = "/ip4/0.0.0.0/tcp/9000";
+
+/// HTTP API tester that allows interaction with the underlying beacon chain harness.
+pub struct InteractiveTester<E: EthSpec> {
+    pub harness: BeaconChainHarness<EphemeralHarnessType<E>>,
+    pub client: BeaconNodeHttpClient,
+    pub network_rx: mpsc::UnboundedReceiver<NetworkMessage<E>>,
+    _server_shutdown: oneshot::Sender<()>,
+}
+
+/// The result of calling `create_api_server`.
+///
+/// Glue-type between `tests::ApiTester` and `InteractiveTester`.
+pub struct ApiServer<E: EthSpec, SFut: Future<Output = ()>> {
+    pub server: SFut,
+    pub listening_socket: SocketAddr,
+    pub shutdown_tx: oneshot::Sender<()>,
+    pub network_rx: tokio::sync::mpsc::UnboundedReceiver<NetworkMessage<E>>,
+    pub local_enr: Enr,
+    pub external_peer_id: PeerId,
+}
+
+impl<E: EthSpec> InteractiveTester<E> {
+    pub fn new(spec: Option<ChainSpec>, validator_count: usize) -> Self {
+        let harness = BeaconChainHarness::new(
+            E::default(),
+            spec,
+            generate_deterministic_keypairs(validator_count),
+        );
+
+        let ApiServer {
+            server,
+            listening_socket,
+            shutdown_tx: _server_shutdown,
+            network_rx,
+            ..
+        } = create_api_server(harness.chain.clone(), harness.logger().clone());
+
+        tokio::spawn(server);
+
+        let client = BeaconNodeHttpClient::new(
+            SensitiveUrl::parse(&format!(
+                "http://{}:{}",
+                listening_socket.ip(),
+                listening_socket.port()
+            ))
+            .unwrap(),
+            Timeouts::set_all(Duration::from_secs(1)),
+        );
+
+        Self {
+            harness,
+            client,
+            network_rx,
+            _server_shutdown,
+        }
+    }
+}
+
+pub fn create_api_server<T: BeaconChainTypes>(
+    chain: Arc<BeaconChain<T>>,
+    log: Logger,
+) -> ApiServer<T::EthSpec, impl Future<Output = ()>> {
+    let (network_tx, network_rx) = mpsc::unbounded_channel();
+
+    // Default metadata
+    let meta_data = MetaData::V2(MetaDataV2 {
+        seq_number: SEQ_NUMBER,
+        attnets: EnrAttestationBitfield::<T::EthSpec>::default(),
+        syncnets: EnrSyncCommitteeBitfield::<T::EthSpec>::default(),
+    });
+    let enr_key = CombinedKey::generate_secp256k1();
+    let enr = EnrBuilder::new("v4").build(&enr_key).unwrap();
+    let network_globals =
+        NetworkGlobals::new(enr.clone(), TCP_PORT, UDP_PORT, meta_data, vec![], &log);
+
+    let peer_id = PeerId::random();
+    network_globals
+        .peers
+        .write()
+        .connect_ingoing(&peer_id, EXTERNAL_ADDR.parse().unwrap(), None);
+
+    *network_globals.sync_state.write() = SyncState::Synced;
+
+    let eth1_service = eth1::Service::new(eth1::Config::default(), log.clone(), chain.spec.clone());
+
+    let context = Arc::new(Context {
+        config: Config {
+            enabled: true,
+            listen_addr: Ipv4Addr::new(127, 0, 0, 1),
+            listen_port: 0,
+            allow_origin: None,
+            serve_legacy_spec: true,
+        },
+        chain: Some(chain.clone()),
+        network_tx: Some(network_tx),
+        network_globals: Some(Arc::new(network_globals)),
+        eth1_service: Some(eth1_service),
+        log,
+    });
+    let ctx = context.clone();
+    let (shutdown_tx, shutdown_rx) = oneshot::channel();
+    let server_shutdown = async {
+        // It's not really interesting why this triggered, just that it happened.
+        let _ = shutdown_rx.await;
+    };
+    let (listening_socket, server) = http_api::serve(ctx, server_shutdown).unwrap();
+
+    ApiServer {
+        server,
+        listening_socket,
+        shutdown_tx,
+        network_rx,
+        local_enr: enr,
+        external_peer_id: peer_id,
+    }
+}

beacon_node/http_api/tests/fork_tests.rs

@@ -0,0 +1,305 @@
+//! Tests for API behaviour across fork boundaries.
+use crate::common::*;
+use beacon_chain::{test_utils::RelativeSyncCommittee, StateSkipConfig};
+use eth2::types::{StateId, SyncSubcommittee};
+use types::{ChainSpec, Epoch, EthSpec, MinimalEthSpec, Slot};
+
+type E = MinimalEthSpec;
+
+fn altair_spec(altair_fork_epoch: Epoch) -> ChainSpec {
+    let mut spec = E::default_spec();
+    spec.altair_fork_epoch = Some(altair_fork_epoch);
+    spec
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn sync_committee_duties_across_fork() {
+    let validator_count = E::sync_committee_size();
+    let fork_epoch = Epoch::new(8);
+    let spec = altair_spec(fork_epoch);
+    let tester = InteractiveTester::<E>::new(Some(spec.clone()), validator_count);
+    let harness = &tester.harness;
+    let client = &tester.client;
+
+    let all_validators = harness.get_all_validators();
+    let all_validators_u64 = all_validators.iter().map(|x| *x as u64).collect::<Vec<_>>();
+
+    assert_eq!(harness.get_current_slot(), 0);
+
+    // Prior to the fork the endpoint should return an empty vec.
+    let early_duties = client
+        .post_validator_duties_sync(fork_epoch - 1, &all_validators_u64)
+        .await
+        .unwrap()
+        .data;
+    assert!(early_duties.is_empty());
+
+    // If there's a skip slot at the fork slot, the endpoint should return duties, even
+    // though the head state hasn't transitioned yet.
+    let fork_slot = fork_epoch.start_slot(E::slots_per_epoch());
+    let (genesis_state, genesis_state_root) = harness.get_current_state_and_root();
+    let (_, state) = harness
+        .add_attested_block_at_slot(
+            fork_slot - 1,
+            genesis_state,
+            genesis_state_root,
+            &all_validators,
+        )
+        .unwrap();
+
+    harness.advance_slot();
+    assert_eq!(harness.get_current_slot(), fork_slot);
+
+    let sync_duties = client
+        .post_validator_duties_sync(fork_epoch, &all_validators_u64)
+        .await
+        .unwrap()
+        .data;
+    assert_eq!(sync_duties.len(), E::sync_committee_size());
+
+    // After applying a block at the fork slot the duties should remain unchanged.
+    let state_root = state.canonical_root();
+    harness
+        .add_attested_block_at_slot(fork_slot, state, state_root, &all_validators)
+        .unwrap();
+
+    assert_eq!(
+        client
+            .post_validator_duties_sync(fork_epoch, &all_validators_u64)
+            .await
+            .unwrap()
+            .data,
+        sync_duties
+    );
+
+    // Sync duties should also be available for the next period.
+    let current_period = fork_epoch.sync_committee_period(&spec).unwrap();
+    let next_period_epoch = spec.epochs_per_sync_committee_period * (current_period + 1);
+
+    let next_period_duties = client
+        .post_validator_duties_sync(next_period_epoch, &all_validators_u64)
+        .await
+        .unwrap()
+        .data;
+    assert_eq!(next_period_duties.len(), E::sync_committee_size());
+
+    // Sync duties should *not* be available for the period after the next period.
+    // We expect a 400 (bad request) response.
+    let next_next_period_epoch = spec.epochs_per_sync_committee_period * (current_period + 2);
+    assert_eq!(
+        client
+            .post_validator_duties_sync(next_next_period_epoch, &all_validators_u64)
+            .await
+            .unwrap_err()
+            .status()
+            .unwrap(),
+        400
+    );
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn attestations_across_fork_with_skip_slots() {
+    let validator_count = E::sync_committee_size();
+    let fork_epoch = Epoch::new(8);
+    let spec = altair_spec(fork_epoch);
+    let tester = InteractiveTester::<E>::new(Some(spec.clone()), validator_count);
+    let harness = &tester.harness;
+    let client = &tester.client;
+
+    let all_validators = harness.get_all_validators();
+
+    let fork_slot = fork_epoch.start_slot(E::slots_per_epoch());
+    let fork_state = harness
+        .chain
+        .state_at_slot(fork_slot, StateSkipConfig::WithStateRoots)
+        .unwrap();
+
+    harness.set_current_slot(fork_slot);
+
+    let attestations = harness.make_attestations(
+        &all_validators,
+        &fork_state,
+        fork_state.canonical_root(),
+        (*fork_state.get_block_root(fork_slot - 1).unwrap()).into(),
+        fork_slot,
+    );
+
+    let unaggregated_attestations = attestations
+        .iter()
+        .flat_map(|(atts, _)| atts.iter().map(|(att, _)| att.clone()))
+        .collect::<Vec<_>>();
+
+    assert!(!unaggregated_attestations.is_empty());
+    client
+        .post_beacon_pool_attestations(&unaggregated_attestations)
+        .await
+        .unwrap();
+
+    let signed_aggregates = attestations
+        .into_iter()
+        .filter_map(|(_, op_aggregate)| op_aggregate)
+        .collect::<Vec<_>>();
+    assert!(!signed_aggregates.is_empty());
+
+    client
+        .post_validator_aggregate_and_proof(&signed_aggregates)
+        .await
+        .unwrap();
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn sync_contributions_across_fork_with_skip_slots() {
+    let validator_count = E::sync_committee_size();
+    let fork_epoch = Epoch::new(8);
+    let spec = altair_spec(fork_epoch);
+    let tester = InteractiveTester::<E>::new(Some(spec.clone()), validator_count);
+    let harness = &tester.harness;
+    let client = &tester.client;
+
+    let fork_slot = fork_epoch.start_slot(E::slots_per_epoch());
+    let fork_state = harness
+        .chain
+        .state_at_slot(fork_slot, StateSkipConfig::WithStateRoots)
+        .unwrap();
+
+    harness.set_current_slot(fork_slot);
+
+    let sync_messages = harness.make_sync_contributions(
+        &fork_state,
+        *fork_state.get_block_root(fork_slot - 1).unwrap(),
+        fork_slot,
+        RelativeSyncCommittee::Current,
+    );
+
+    let sync_committee_messages = sync_messages
+        .iter()
+        .flat_map(|(messages, _)| messages.iter().map(|(message, _subnet)| message.clone()))
+        .collect::<Vec<_>>();
+    assert!(!sync_committee_messages.is_empty());
+
+    client
+        .post_beacon_pool_sync_committee_signatures(&sync_committee_messages)
+        .await
+        .unwrap();
+
+    let signed_contributions = sync_messages
+        .into_iter()
+        .filter_map(|(_, op_aggregate)| op_aggregate)
+        .collect::<Vec<_>>();
+    assert!(!signed_contributions.is_empty());
+
+    client
+        .post_validator_contribution_and_proofs(&signed_contributions)
+        .await
+        .unwrap();
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn sync_committee_indices_across_fork() {
+    let validator_count = E::sync_committee_size();
+    let fork_epoch = Epoch::new(8);
+    let spec = altair_spec(fork_epoch);
+    let tester = InteractiveTester::<E>::new(Some(spec.clone()), validator_count);
+    let harness = &tester.harness;
+    let client = &tester.client;
+
+    let all_validators = harness.get_all_validators();
+
+    // Flatten subcommittees into a single vec.
+    let flatten = |subcommittees: &[SyncSubcommittee]| -> Vec<u64> {
+        subcommittees
+            .iter()
+            .flat_map(|sub| sub.indices.iter().copied())
+            .collect()
+    };
+
+    // Prior to the fork the `sync_committees` endpoint should return a 400 error.
+    assert_eq!(
+        client
+            .get_beacon_states_sync_committees(StateId::Slot(Slot::new(0)), None)
+            .await
+            .unwrap_err()
+            .status()
+            .unwrap(),
+        400
+    );
+    assert_eq!(
+        client
+            .get_beacon_states_sync_committees(StateId::Head, Some(Epoch::new(0)))
+            .await
+            .unwrap_err()
+            .status()
+            .unwrap(),
+        400
+    );
+
+    // If there's a skip slot at the fork slot, the endpoint will return a 400 until a block is
+    // applied.
+    let fork_slot = fork_epoch.start_slot(E::slots_per_epoch());
+    let (genesis_state, genesis_state_root) = harness.get_current_state_and_root();
+    let (_, state) = harness
+        .add_attested_block_at_slot(
+            fork_slot - 1,
+            genesis_state,
+            genesis_state_root,
+            &all_validators,
+        )
+        .unwrap();
+
+    harness.advance_slot();
+    assert_eq!(harness.get_current_slot(), fork_slot);
+
+    // Using the head state must fail.
+    assert_eq!(
+        client
+            .get_beacon_states_sync_committees(StateId::Head, Some(fork_epoch))
+            .await
+            .unwrap_err()
+            .status()
+            .unwrap(),
+        400
+    );
+
+    // In theory we could do a state advance and make this work, but to keep things simple I've
+    // avoided doing that for now.
+    assert_eq!(
+        client
+            .get_beacon_states_sync_committees(StateId::Slot(fork_slot), None)
+            .await
+            .unwrap_err()
+            .status()
+            .unwrap(),
+        400
+    );
+
+    // Once the head is updated it should be useable for requests, including in the next sync
+    // committee period.
+    let state_root = state.canonical_root();
+    harness
+        .add_attested_block_at_slot(fork_slot + 1, state, state_root, &all_validators)
+        .unwrap();
+
+    let current_period = fork_epoch.sync_committee_period(&spec).unwrap();
+    let next_period_epoch = spec.epochs_per_sync_committee_period * (current_period + 1);
+    assert!(next_period_epoch > fork_epoch);
+
+    for epoch in [
+        None,
+        Some(fork_epoch),
+        Some(fork_epoch + 1),
+        Some(next_period_epoch),
+        Some(next_period_epoch + 1),
+    ] {
+        let committee = client
+            .get_beacon_states_sync_committees(StateId::Head, epoch)
+            .await
+            .unwrap()
+            .data;
+        assert_eq!(committee.validators.len(), E::sync_committee_size());
+
+        assert_eq!(
+            committee.validators,
+            flatten(&committee.validator_aggregates)
+        );
+    }
+}

beacon_node/http_api/tests/main.rs

@@ -0,0 +1,6 @@
+#![cfg(not(debug_assertions))] // Tests are too slow in debug.
+#![recursion_limit = "256"]
+
+pub mod common;
+pub mod fork_tests;
+pub mod tests;

beacon_node/http_api/tests/tests.rs

@@ -1,6 +1,4 @@
-#![cfg(not(debug_assertions))] // Tests are too slow in debug.
-#![recursion_limit = "256"]
-
+use crate::common::{create_api_server, ApiServer};
 use beacon_chain::{
     test_utils::{AttestationStrategy, BeaconChainHarness, BlockStrategy, EphemeralHarnessType},
     BeaconChain, StateSkipConfig, WhenSlotSkipped, MAXIMUM_GOSSIP_CLOCK_DISPARITY,
@@ -9,21 +7,14 @@ use environment::null_logger;
 use eth2::Error;
 use eth2::StatusCode;
 use eth2::{types::*, BeaconNodeHttpClient, Timeouts};
-use eth2_libp2p::discv5::enr::{CombinedKey, EnrBuilder};
-use eth2_libp2p::{
-    rpc::methods::{MetaData, MetaDataV2},
-    types::{EnrAttestationBitfield, EnrSyncCommitteeBitfield, SyncState},
-    Enr, EnrExt, NetworkGlobals, PeerId,
-};
+use eth2_libp2p::{Enr, EnrExt, PeerId};
 use futures::stream::{Stream, StreamExt};
 use futures::FutureExt;
-use http_api::{Config, Context};
 use network::NetworkMessage;
 use sensitive_url::SensitiveUrl;
 use slot_clock::SlotClock;
 use state_processing::per_slot_processing;
 use std::convert::TryInto;
-use std::net::Ipv4Addr;
 use std::sync::Arc;
 use tokio::sync::{mpsc, oneshot};
 use tokio::time::Duration;
@@ -41,9 +32,6 @@ const VALIDATOR_COUNT: usize = SLOTS_PER_EPOCH as usize;
 const CHAIN_LENGTH: u64 = SLOTS_PER_EPOCH * 5 - 1; // Make `next_block` an epoch transition
 const JUSTIFIED_EPOCH: u64 = 4;
 const FINALIZED_EPOCH: u64 = 3;
-const TCP_PORT: u16 = 42;
-const UDP_PORT: u16 = 42;
-const SEQ_NUMBER: u64 = 0;
 const EXTERNAL_ADDR: &str = "/ip4/0.0.0.0/tcp/9000";
 
 /// Skipping the slots around the epoch boundary allows us to check that we're obtaining states
@@ -74,9 +62,13 @@ struct ApiTester {
 
 impl ApiTester {
     pub fn new() -> Self {
-        let mut harness = BeaconChainHarness::new(
+        // This allows for testing voluntary exits without building out a massive chain.
+        let mut spec = E::default_spec();
+        spec.shard_committee_period = 2;
+
+        let harness = BeaconChainHarness::new(
             MainnetEthSpec,
-            None,
+            Some(spec),
             generate_deterministic_keypairs(VALIDATOR_COUNT),
         );
 
@@ -134,13 +126,7 @@ impl ApiTester {
         let proposer_slashing = harness.make_proposer_slashing(2);
         let voluntary_exit = harness.make_voluntary_exit(3, harness.chain.epoch().unwrap());
 
-        // Changing this *after* the chain has been initialized is a bit cheeky, but it shouldn't
-        // cause issue.
-        //
-        // This allows for testing voluntary exits without building out a massive chain.
-        harness.chain.spec.shard_committee_period = 2;
-
-        let chain = Arc::new(harness.chain);
+        let chain = harness.chain.clone();
 
         assert_eq!(
             chain.head_info().unwrap().finalized_checkpoint.epoch,
@@ -157,56 +143,18 @@ impl ApiTester {
             "precondition: justification"
         );
 
-        let (network_tx, network_rx) = mpsc::unbounded_channel();
-
         let log = null_logger().unwrap();
 
-        // Default metadata
-        let meta_data = MetaData::V2(MetaDataV2 {
-            seq_number: SEQ_NUMBER,
-            attnets: EnrAttestationBitfield::<MainnetEthSpec>::default(),
-            syncnets: EnrSyncCommitteeBitfield::<MainnetEthSpec>::default(),
-        });
-        let enr_key = CombinedKey::generate_secp256k1();
-        let enr = EnrBuilder::new("v4").build(&enr_key).unwrap();
-        let enr_clone = enr.clone();
-        let network_globals = NetworkGlobals::new(enr, TCP_PORT, UDP_PORT, meta_data, vec![], &log);
+        let ApiServer {
+            server,
+            listening_socket,
+            shutdown_tx,
+            network_rx,
+            local_enr,
+            external_peer_id,
+        } = create_api_server(chain.clone(), log);
 
-        let peer_id = PeerId::random();
-        network_globals.peers.write().connect_ingoing(
-            &peer_id,
-            EXTERNAL_ADDR.parse().unwrap(),
-            None,
-        );
-
-        *network_globals.sync_state.write() = SyncState::Synced;
-
-        let eth1_service =
-            eth1::Service::new(eth1::Config::default(), log.clone(), chain.spec.clone());
-
-        let context = Arc::new(Context {
-            config: Config {
-                enabled: true,
-                listen_addr: Ipv4Addr::new(127, 0, 0, 1),
-                listen_port: 0,
-                allow_origin: None,
-                serve_legacy_spec: true,
-            },
-            chain: Some(chain.clone()),
-            network_tx: Some(network_tx),
-            network_globals: Some(Arc::new(network_globals)),
-            eth1_service: Some(eth1_service),
-            log,
-        });
-        let ctx = context.clone();
-        let (shutdown_tx, shutdown_rx) = oneshot::channel();
-        let server_shutdown = async {
-            // It's not really interesting why this triggered, just that it happened.
-            let _ = shutdown_rx.await;
-        };
-        let (listening_socket, server) = http_api::serve(ctx, server_shutdown).unwrap();
-
-        tokio::spawn(async { server.await });
+        tokio::spawn(server);
 
         let client = BeaconNodeHttpClient::new(
             SensitiveUrl::parse(&format!(
@@ -230,8 +178,8 @@ impl ApiTester {
             _server_shutdown: shutdown_tx,
             validator_keypairs: harness.validator_keypairs,
             network_rx,
-            local_enr: enr_clone,
-            external_peer_id: peer_id,
+            local_enr,
+            external_peer_id,
         }
     }
 
@@ -271,58 +219,20 @@ impl ApiTester {
         let proposer_slashing = harness.make_proposer_slashing(2);
         let voluntary_exit = harness.make_voluntary_exit(3, harness.chain.epoch().unwrap());
 
-        let chain = Arc::new(harness.chain);
-
-        let (network_tx, network_rx) = mpsc::unbounded_channel();
+        let chain = harness.chain.clone();
 
         let log = null_logger().unwrap();
 
-        // Default metadata
-        let meta_data = MetaData::V2(MetaDataV2 {
-            seq_number: SEQ_NUMBER,
-            attnets: EnrAttestationBitfield::<MainnetEthSpec>::default(),
-            syncnets: EnrSyncCommitteeBitfield::<MainnetEthSpec>::default(),
-        });
-        let enr_key = CombinedKey::generate_secp256k1();
-        let enr = EnrBuilder::new("v4").build(&enr_key).unwrap();
-        let enr_clone = enr.clone();
-        let network_globals = NetworkGlobals::new(enr, TCP_PORT, UDP_PORT, meta_data, vec![], &log);
+        let ApiServer {
+            server,
+            listening_socket,
+            shutdown_tx,
+            network_rx,
+            local_enr,
+            external_peer_id,
+        } = create_api_server(chain.clone(), log);
 
-        let peer_id = PeerId::random();
-        network_globals.peers.write().connect_ingoing(
-            &peer_id,
-            EXTERNAL_ADDR.parse().unwrap(),
-            None,
-        );
-
-        *network_globals.sync_state.write() = SyncState::Synced;
-
-        let eth1_service =
-            eth1::Service::new(eth1::Config::default(), log.clone(), chain.spec.clone());
-
-        let context = Arc::new(Context {
-            config: Config {
-                enabled: true,
-                listen_addr: Ipv4Addr::new(127, 0, 0, 1),
-                listen_port: 0,
-                allow_origin: None,
-                serve_legacy_spec: true,
-            },
-            chain: Some(chain.clone()),
-            network_tx: Some(network_tx),
-            network_globals: Some(Arc::new(network_globals)),
-            eth1_service: Some(eth1_service),
-            log,
-        });
-        let ctx = context.clone();
-        let (shutdown_tx, shutdown_rx) = oneshot::channel();
-        let server_shutdown = async {
-            // It's not really interesting why this triggered, just that it happened.
-            let _ = shutdown_rx.await;
-        };
-        let (listening_socket, server) = http_api::serve(ctx, server_shutdown).unwrap();
-
-        tokio::spawn(async { server.await });
+        tokio::spawn(server);
 
         let client = BeaconNodeHttpClient::new(
             SensitiveUrl::parse(&format!(
@@ -346,8 +256,8 @@ impl ApiTester {
             _server_shutdown: shutdown_tx,
             validator_keypairs: harness.validator_keypairs,
             network_rx,
-            local_enr: enr_clone,
-            external_peer_id: peer_id,
+            local_enr,
+            external_peer_id,
         }
     }
 
@@ -1011,13 +921,18 @@ impl ApiTester {
                 }
             }
 
-            let json_result = self
-                .client
-                .get_beacon_blocks(block_id)
-                .await
-                .unwrap()
-                .map(|res| res.data);
-            assert_eq!(json_result, expected, "{:?}", block_id);
+            let json_result = self.client.get_beacon_blocks(block_id).await.unwrap();
+
+            if let (Some(json), Some(expected)) = (&json_result, &expected) {
+                assert_eq!(json.data, *expected, "{:?}", block_id);
+                assert_eq!(
+                    json.version,
+                    Some(expected.fork_name(&self.chain.spec).unwrap())
+                );
+            } else {
+                assert_eq!(json_result, None);
+                assert_eq!(expected, None);
+            }
 
             let ssz_result = self
                 .client
@@ -1025,6 +940,16 @@ impl ApiTester {
                 .await
                 .unwrap();
             assert_eq!(ssz_result, expected, "{:?}", block_id);
+
+            // Check that the legacy v1 API still works but doesn't return a version field.
+            let v1_result = self.client.get_beacon_blocks_v1(block_id).await.unwrap();
+            if let (Some(v1_result), Some(expected)) = (&v1_result, &expected) {
+                assert_eq!(v1_result.version, None);
+                assert_eq!(v1_result.data, *expected);
+            } else {
+                assert_eq!(v1_result, None);
+                assert_eq!(expected, None);
+            }
         }
 
         self
@@ -1443,23 +1368,44 @@ impl ApiTester {
 
     pub async fn test_get_debug_beacon_states(self) -> Self {
         for state_id in self.interesting_state_ids() {
+            let result_json = self.client.get_debug_beacon_states(state_id).await.unwrap();
+
+            let mut expected = self.get_state(state_id);
+            expected.as_mut().map(|state| state.drop_all_caches());
+
+            if let (Some(json), Some(expected)) = (&result_json, &expected) {
+                assert_eq!(json.data, *expected, "{:?}", state_id);
+                assert_eq!(
+                    json.version,
+                    Some(expected.fork_name(&self.chain.spec).unwrap())
+                );
+            } else {
+                assert_eq!(result_json, None);
+                assert_eq!(expected, None);
+            }
+
+            // Check SSZ API.
             let result_ssz = self
                 .client
                 .get_debug_beacon_states_ssz(state_id, &self.chain.spec)
                 .await
                 .unwrap();
-            let result_json = self
-                .client
-                .get_debug_beacon_states(state_id)
-                .await
-                .unwrap()
-                .map(|res| res.data);
-
-            let mut expected = self.get_state(state_id);
-            expected.as_mut().map(|state| state.drop_all_caches());
-
             assert_eq!(result_ssz, expected, "{:?}", state_id);
-            assert_eq!(result_json, expected, "{:?}", state_id);
+
+            // Check legacy v1 API.
+            let result_v1 = self
+                .client
+                .get_debug_beacon_states_v1(state_id)
+                .await
+                .unwrap();
+
+            if let (Some(json), Some(expected)) = (&result_v1, &expected) {
+                assert_eq!(json.version, None);
+                assert_eq!(json.data, *expected, "{:?}", state_id);
+            } else {
+                assert_eq!(result_v1, None);
+                assert_eq!(expected, None);
+            }
         }
 
         self

beacon_node/network/src/beacon_processor/tests.rs

@@ -23,8 +23,8 @@ use std::time::Duration;
 use tokio::runtime::Runtime;
 use tokio::sync::mpsc;
 use types::{
-    test_utils::generate_deterministic_keypairs, Attestation, AttesterSlashing, MainnetEthSpec,
-    ProposerSlashing, SignedBeaconBlock, SignedVoluntaryExit, SubnetId,
+    test_utils::generate_deterministic_keypairs, Attestation, AttesterSlashing, EthSpec,
+    MainnetEthSpec, ProposerSlashing, SignedBeaconBlock, SignedVoluntaryExit, SubnetId,
 };
 
 type E = MainnetEthSpec;
@@ -71,9 +71,13 @@ impl Drop for TestRig {
 
 impl TestRig {
     pub fn new(chain_length: u64) -> Self {
-        let mut harness = BeaconChainHarness::new(
+        // This allows for testing voluntary exits without building out a massive chain.
+        let mut spec = E::default_spec();
+        spec.shard_committee_period = 2;
+
+        let harness = BeaconChainHarness::new(
             MainnetEthSpec,
-            None,
+            Some(spec),
             generate_deterministic_keypairs(VALIDATOR_COUNT),
         );
 
@@ -151,13 +155,7 @@ impl TestRig {
         let proposer_slashing = harness.make_proposer_slashing(2);
         let voluntary_exit = harness.make_voluntary_exit(3, harness.chain.epoch().unwrap());
 
-        // Changing this *after* the chain has been initialized is a bit cheeky, but it shouldn't
-        // cause issue.
-        //
-        // This allows for testing voluntary exits without building out a massive chain.
-        harness.chain.spec.shard_committee_period = 2;
-
-        let chain = Arc::new(harness.chain);
+        let chain = harness.chain;
 
         let (network_tx, _network_rx) = mpsc::unbounded_channel();
 

beacon_node/network/src/beacon_processor/worker/mod.rs

@@ -27,8 +27,8 @@ impl<T: BeaconChainTypes> Worker<T> {
     /// Creates a log if there is an internal error.
     fn send_sync_message(&self, message: SyncMessage<T::EthSpec>) {
         self.sync_tx.send(message).unwrap_or_else(|e| {
-            debug!(self.log, "Could not send message to the sync service, likely shutdown";
-                "error" => %e)
+            debug!(self.log, "Could not send message to the sync service";
+                   "error" => %e)
         });
     }
 

beacon_node/network/src/service/tests.rs

@@ -35,15 +35,13 @@ mod tests {
     fn test_dht_persistence() {
         let log = get_logger(false);
 
-        let beacon_chain = Arc::new(
-            BeaconChainHarness::new_with_store_config(
-                MinimalEthSpec,
-                None,
-                generate_deterministic_keypairs(8),
-                StoreConfig::default(),
-            )
-            .chain,
-        );
+        let beacon_chain = BeaconChainHarness::new_with_store_config(
+            MinimalEthSpec,
+            None,
+            generate_deterministic_keypairs(8),
+            StoreConfig::default(),
+        )
+        .chain;
 
         let store = beacon_chain.store.clone();
 

boot_node/src/server.rs

@@ -40,13 +40,22 @@ pub async fn run<T: EthSpec>(config: BootNodeConfig<T>, log: slog::Logger) {
     };
 
     // construct the discv5 server
-    let mut discv5 = Discv5::new(config.local_enr, config.local_key, discv5_config).unwrap();
+    let mut discv5 =
+        Discv5::new(config.local_enr.clone(), config.local_key, discv5_config).unwrap();
 
     // If there are any bootnodes add them to the routing table
     for enr in config.boot_nodes {
-        info!(log, "Adding bootnode"; "address" => format!("{:?}", enr.udp_socket()), "peer_id" => enr.peer_id().to_string(), "node_id" => enr.node_id().to_string());
-        if let Err(e) = discv5.add_enr(enr) {
-            slog::warn!(log, "Failed adding ENR"; "error" => e.to_string());
+        info!(
+            log,
+            "Adding bootnode";
+            "address" => ?enr.udp_socket(),
+            "peer_id" => enr.peer_id().to_string(),
+            "node_id" => enr.node_id().to_string()
+        );
+        if enr != config.local_enr {
+            if let Err(e) = discv5.add_enr(enr) {
+                slog::warn!(log, "Failed adding ENR"; "error" => e.to_string());
+            }
         }
     }
 

common/eth2/src/lib.rs

@@ -12,7 +12,7 @@ pub mod lighthouse;
 pub mod lighthouse_vc;
 pub mod types;
 
-use self::types::*;
+use self::types::{Error as ResponseError, *};
 use eth2_libp2p::PeerId;
 use futures::Stream;
 use futures_util::StreamExt;
@@ -26,6 +26,9 @@ use std::fmt;
 use std::iter::Iterator;
 use std::time::Duration;
 
+pub const V1: EndpointVersion = EndpointVersion(1);
+pub const V2: EndpointVersion = EndpointVersion(2);
+
 #[derive(Debug)]
 pub enum Error {
     /// The `reqwest` client raised an error.
@@ -86,6 +89,7 @@ pub struct Timeouts {
     pub liveness: Duration,
     pub proposal: Duration,
     pub proposer_duties: Duration,
+    pub sync_duties: Duration,
 }
 
 impl Timeouts {
@@ -96,6 +100,7 @@ impl Timeouts {
             liveness: timeout,
             proposal: timeout,
             proposer_duties: timeout,
+            sync_duties: timeout,
         }
     }
 }
@@ -142,14 +147,14 @@ impl BeaconNodeHttpClient {
         }
     }
 
-    /// Return the path with the standard `/eth1/v1` prefix applied.
-    fn eth_path(&self) -> Result<Url, Error> {
+    /// Return the path with the standard `/eth/vX` prefix applied.
+    fn eth_path(&self, version: EndpointVersion) -> Result<Url, Error> {
         let mut path = self.server.full.clone();
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
             .push("eth")
-            .push("v1");
+            .push(&version.to_string());
 
         Ok(path)
     }
@@ -315,7 +320,7 @@ impl BeaconNodeHttpClient {
     ///
     /// May return a `404` if beacon chain genesis has not yet occurred.
     pub async fn get_beacon_genesis(&self) -> Result<GenericResponse<GenesisData>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -332,7 +337,7 @@ impl BeaconNodeHttpClient {
         &self,
         state_id: StateId,
     ) -> Result<Option<GenericResponse<RootData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -351,7 +356,7 @@ impl BeaconNodeHttpClient {
         &self,
         state_id: StateId,
     ) -> Result<Option<GenericResponse<Fork>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -370,7 +375,7 @@ impl BeaconNodeHttpClient {
         &self,
         state_id: StateId,
     ) -> Result<Option<GenericResponse<FinalityCheckpointsData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -390,7 +395,7 @@ impl BeaconNodeHttpClient {
         state_id: StateId,
         ids: Option<&[ValidatorId]>,
     ) -> Result<Option<GenericResponse<Vec<ValidatorBalanceData>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -420,7 +425,7 @@ impl BeaconNodeHttpClient {
         ids: Option<&[ValidatorId]>,
         statuses: Option<&[ValidatorStatus]>,
     ) -> Result<Option<GenericResponse<Vec<ValidatorData>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -460,7 +465,7 @@ impl BeaconNodeHttpClient {
         index: Option<u64>,
         epoch: Option<Epoch>,
     ) -> Result<Option<GenericResponse<Vec<CommitteeData>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -487,6 +492,29 @@ impl BeaconNodeHttpClient {
         self.get_opt(path).await
     }
 
+    /// `GET beacon/states/{state_id}/sync_committees?epoch`
+    pub async fn get_beacon_states_sync_committees(
+        &self,
+        state_id: StateId,
+        epoch: Option<Epoch>,
+    ) -> Result<GenericResponse<SyncCommitteeByValidatorIndices>, Error> {
+        let mut path = self.eth_path(V1)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("beacon")
+            .push("states")
+            .push(&state_id.to_string())
+            .push("sync_committees");
+
+        if let Some(epoch) = epoch {
+            path.query_pairs_mut()
+                .append_pair("epoch", &epoch.to_string());
+        }
+
+        self.get(path).await
+    }
+
     /// `GET beacon/states/{state_id}/validators/{validator_id}`
     ///
     /// Returns `Ok(None)` on a 404 error.
@@ -495,7 +523,7 @@ impl BeaconNodeHttpClient {
         state_id: StateId,
         validator_id: &ValidatorId,
     ) -> Result<Option<GenericResponse<ValidatorData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -516,7 +544,7 @@ impl BeaconNodeHttpClient {
         slot: Option<Slot>,
         parent_root: Option<Hash256>,
     ) -> Result<Option<GenericResponse<Vec<BlockHeaderData>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -543,7 +571,7 @@ impl BeaconNodeHttpClient {
         &self,
         block_id: BlockId,
     ) -> Result<Option<GenericResponse<BlockHeaderData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -561,7 +589,7 @@ impl BeaconNodeHttpClient {
         &self,
         block: &SignedBeaconBlock<T>,
     ) -> Result<(), Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -574,14 +602,32 @@ impl BeaconNodeHttpClient {
         Ok(())
     }
 
-    /// `GET beacon/blocks`
+    /// `GET v2/beacon/blocks`
     ///
     /// Returns `Ok(None)` on a 404 error.
     pub async fn get_beacon_blocks<T: EthSpec>(
         &self,
         block_id: BlockId,
-    ) -> Result<Option<GenericResponse<SignedBeaconBlock<T>>>, Error> {
-        let mut path = self.eth_path()?;
+    ) -> Result<Option<ForkVersionedResponse<SignedBeaconBlock<T>>>, Error> {
+        let mut path = self.eth_path(V2)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("beacon")
+            .push("blocks")
+            .push(&block_id.to_string());
+
+        self.get_opt(path).await
+    }
+
+    /// `GET v1/beacon/blocks` (LEGACY)
+    ///
+    /// Returns `Ok(None)` on a 404 error.
+    pub async fn get_beacon_blocks_v1<T: EthSpec>(
+        &self,
+        block_id: BlockId,
+    ) -> Result<Option<ForkVersionedResponse<SignedBeaconBlock<T>>>, Error> {
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -600,7 +646,7 @@ impl BeaconNodeHttpClient {
         block_id: BlockId,
         spec: &ChainSpec,
     ) -> Result<Option<SignedBeaconBlock<T>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V2)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -621,7 +667,7 @@ impl BeaconNodeHttpClient {
         &self,
         block_id: BlockId,
     ) -> Result<Option<GenericResponse<RootData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -640,7 +686,7 @@ impl BeaconNodeHttpClient {
         &self,
         block_id: BlockId,
     ) -> Result<Option<GenericResponse<Vec<Attestation<T>>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -657,7 +703,7 @@ impl BeaconNodeHttpClient {
         &self,
         attestations: &[Attestation<T>],
     ) -> Result<(), Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -665,15 +711,8 @@ impl BeaconNodeHttpClient {
             .push("pool")
             .push("attestations");
 
-        let response = self
-            .client
-            .post(path)
-            .timeout(self.timeouts.attestation)
-            .json(attestations)
-            .send()
-            .await
-            .map_err(Error::Reqwest)?;
-        ok_or_indexed_error(response).await?;
+        self.post_with_timeout(path, &attestations, self.timeouts.attestation)
+            .await?;
 
         Ok(())
     }
@@ -684,7 +723,7 @@ impl BeaconNodeHttpClient {
         slot: Option<Slot>,
         committee_index: Option<u64>,
     ) -> Result<GenericResponse<Vec<Attestation<T>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -710,7 +749,7 @@ impl BeaconNodeHttpClient {
         &self,
         slashing: &AttesterSlashing<T>,
     ) -> Result<(), Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -727,7 +766,7 @@ impl BeaconNodeHttpClient {
     pub async fn get_beacon_pool_attester_slashings<T: EthSpec>(
         &self,
     ) -> Result<GenericResponse<Vec<AttesterSlashing<T>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -743,7 +782,7 @@ impl BeaconNodeHttpClient {
         &self,
         slashing: &ProposerSlashing,
     ) -> Result<(), Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -760,7 +799,7 @@ impl BeaconNodeHttpClient {
     pub async fn get_beacon_pool_proposer_slashings(
         &self,
     ) -> Result<GenericResponse<Vec<ProposerSlashing>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -776,7 +815,7 @@ impl BeaconNodeHttpClient {
         &self,
         exit: &SignedVoluntaryExit,
     ) -> Result<(), Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -793,7 +832,7 @@ impl BeaconNodeHttpClient {
     pub async fn get_beacon_pool_voluntary_exits(
         &self,
     ) -> Result<GenericResponse<Vec<SignedVoluntaryExit>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -804,9 +843,44 @@ impl BeaconNodeHttpClient {
         self.get(path).await
     }
 
+    /// `POST beacon/pool/sync_committees`
+    pub async fn post_beacon_pool_sync_committee_signatures(
+        &self,
+        signatures: &[SyncCommitteeMessage],
+    ) -> Result<(), Error> {
+        let mut path = self.eth_path(V1)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("beacon")
+            .push("pool")
+            .push("sync_committees");
+
+        self.post(path, &signatures).await?;
+
+        Ok(())
+    }
+
+    /// `POST validator/contribution_and_proofs`
+    pub async fn post_validator_contribution_and_proofs<T: EthSpec>(
+        &self,
+        signed_contributions: &[SignedContributionAndProof<T>],
+    ) -> Result<(), Error> {
+        let mut path = self.eth_path(V1)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("validator")
+            .push("contribution_and_proofs");
+
+        self.post(path, &signed_contributions).await?;
+
+        Ok(())
+    }
+
     /// `GET config/fork_schedule`
     pub async fn get_config_fork_schedule(&self) -> Result<GenericResponse<Vec<Fork>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -818,7 +892,7 @@ impl BeaconNodeHttpClient {
 
     /// `GET config/spec`
     pub async fn get_config_spec(&self) -> Result<GenericResponse<ConfigAndPreset>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -832,7 +906,7 @@ impl BeaconNodeHttpClient {
     pub async fn get_config_deposit_contract(
         &self,
     ) -> Result<GenericResponse<DepositContractData>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -844,7 +918,7 @@ impl BeaconNodeHttpClient {
 
     /// `GET node/version`
     pub async fn get_node_version(&self) -> Result<GenericResponse<VersionData>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -856,7 +930,7 @@ impl BeaconNodeHttpClient {
 
     /// `GET node/identity`
     pub async fn get_node_identity(&self) -> Result<GenericResponse<IdentityData>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -868,7 +942,7 @@ impl BeaconNodeHttpClient {
 
     /// `GET node/syncing`
     pub async fn get_node_syncing(&self) -> Result<GenericResponse<SyncingData>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -880,7 +954,7 @@ impl BeaconNodeHttpClient {
 
     /// `GET node/health`
     pub async fn get_node_health(&self) -> Result<StatusCode, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -906,7 +980,7 @@ impl BeaconNodeHttpClient {
         &self,
         peer_id: PeerId,
     ) -> Result<GenericResponse<PeerData>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -923,7 +997,7 @@ impl BeaconNodeHttpClient {
         states: Option<&[PeerState]>,
         directions: Option<&[PeerDirection]>,
     ) -> Result<PeersData, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -953,7 +1027,7 @@ impl BeaconNodeHttpClient {
 
     /// `GET node/peer_count`
     pub async fn get_node_peer_count(&self) -> Result<GenericResponse<PeerCount>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -963,12 +1037,29 @@ impl BeaconNodeHttpClient {
         self.get(path).await
     }
 
-    /// `GET debug/beacon/states/{state_id}`
+    /// `GET v2/debug/beacon/states/{state_id}`
     pub async fn get_debug_beacon_states<T: EthSpec>(
         &self,
         state_id: StateId,
-    ) -> Result<Option<GenericResponse<BeaconState<T>>>, Error> {
-        let mut path = self.eth_path()?;
+    ) -> Result<Option<ForkVersionedResponse<BeaconState<T>>>, Error> {
+        let mut path = self.eth_path(V2)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("debug")
+            .push("beacon")
+            .push("states")
+            .push(&state_id.to_string());
+
+        self.get_opt(path).await
+    }
+
+    /// `GET v1/debug/beacon/states/{state_id}` (LEGACY)
+    pub async fn get_debug_beacon_states_v1<T: EthSpec>(
+        &self,
+        state_id: StateId,
+    ) -> Result<Option<ForkVersionedResponse<BeaconState<T>>>, Error> {
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -987,7 +1078,7 @@ impl BeaconNodeHttpClient {
         state_id: StateId,
         spec: &ChainSpec,
     ) -> Result<Option<BeaconState<T>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1006,7 +1097,7 @@ impl BeaconNodeHttpClient {
     pub async fn get_debug_beacon_heads(
         &self,
     ) -> Result<GenericResponse<Vec<ChainHeadData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1022,7 +1113,7 @@ impl BeaconNodeHttpClient {
         &self,
         epoch: Epoch,
     ) -> Result<DutiesResponse<Vec<ProposerData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1035,14 +1126,14 @@ impl BeaconNodeHttpClient {
             .await
     }
 
-    /// `GET validator/blocks/{slot}`
+    /// `GET v2/validator/blocks/{slot}`
     pub async fn get_validator_blocks<T: EthSpec>(
         &self,
         slot: Slot,
         randao_reveal: &SignatureBytes,
         graffiti: Option<&Graffiti>,
-    ) -> Result<GenericResponse<BeaconBlock<T>>, Error> {
-        let mut path = self.eth_path()?;
+    ) -> Result<ForkVersionedResponse<BeaconBlock<T>>, Error> {
+        let mut path = self.eth_path(V2)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1067,7 +1158,7 @@ impl BeaconNodeHttpClient {
         slot: Slot,
         committee_index: CommitteeIndex,
     ) -> Result<GenericResponse<AttestationData>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1087,7 +1178,7 @@ impl BeaconNodeHttpClient {
         slot: Slot,
         attestation_data_root: Hash256,
     ) -> Result<Option<GenericResponse<Attestation<T>>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1105,6 +1196,32 @@ impl BeaconNodeHttpClient {
             .await
     }
 
+    /// `GET validator/sync_committee_contribution`
+    pub async fn get_validator_sync_committee_contribution<T: EthSpec>(
+        &self,
+        sync_committee_data: &SyncContributionData,
+    ) -> Result<Option<GenericResponse<SyncCommitteeContribution<T>>>, Error> {
+        let mut path = self.eth_path(V1)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("validator")
+            .push("sync_committee_contribution");
+
+        path.query_pairs_mut()
+            .append_pair("slot", &sync_committee_data.slot.to_string())
+            .append_pair(
+                "beacon_block_root",
+                &format!("{:?}", sync_committee_data.beacon_block_root),
+            )
+            .append_pair(
+                "subcommittee_index",
+                &sync_committee_data.subcommittee_index.to_string(),
+            );
+
+        self.get_opt(path).await
+    }
+
     /// `POST lighthouse/liveness`
     pub async fn post_lighthouse_liveness(
         &self,
@@ -1135,7 +1252,7 @@ impl BeaconNodeHttpClient {
         epoch: Epoch,
         indices: &[u64],
     ) -> Result<DutiesResponse<Vec<AttesterData>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1153,22 +1270,15 @@ impl BeaconNodeHttpClient {
         &self,
         aggregates: &[SignedAggregateAndProof<T>],
     ) -> Result<(), Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
             .push("validator")
             .push("aggregate_and_proofs");
 
-        let response = self
-            .client
-            .post(path)
-            .timeout(self.timeouts.attestation)
-            .json(aggregates)
-            .send()
-            .await
-            .map_err(Error::Reqwest)?;
-        ok_or_indexed_error(response).await?;
+        self.post_with_timeout(path, &aggregates, self.timeouts.attestation)
+            .await?;
 
         Ok(())
     }
@@ -1178,7 +1288,7 @@ impl BeaconNodeHttpClient {
         &self,
         subscriptions: &[BeaconCommitteeSubscription],
     ) -> Result<(), Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
 
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
@@ -1190,12 +1300,29 @@ impl BeaconNodeHttpClient {
         Ok(())
     }
 
+    /// `POST validator/sync_committee_subscriptions`
+    pub async fn post_validator_sync_committee_subscriptions(
+        &self,
+        subscriptions: &[SyncCommitteeSubscription],
+    ) -> Result<(), Error> {
+        let mut path = self.eth_path(V1)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("validator")
+            .push("sync_committee_subscriptions");
+
+        self.post(path, &subscriptions).await?;
+
+        Ok(())
+    }
+
     /// `GET events?topics`
     pub async fn get_events<T: EthSpec>(
         &self,
         topic: &[EventTopic],
     ) -> Result<impl Stream<Item = Result<EventKind<T>, Error>>, Error> {
-        let mut path = self.eth_path()?;
+        let mut path = self.eth_path(V1)?;
         path.path_segments_mut()
             .map_err(|()| Error::InvalidUrl(self.server.clone()))?
             .push("events");
@@ -1219,6 +1346,25 @@ impl BeaconNodeHttpClient {
                 Err(e) => Err(Error::Reqwest(e)),
             }))
     }
+
+    /// `POST validator/duties/sync/{epoch}`
+    pub async fn post_validator_duties_sync(
+        &self,
+        epoch: Epoch,
+        indices: &[u64],
+    ) -> Result<GenericResponse<Vec<SyncDuty>>, Error> {
+        let mut path = self.eth_path(V1)?;
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("validator")
+            .push("duties")
+            .push("sync")
+            .push(&epoch.to_string());
+
+        self.post_with_timeout_and_response(path, &indices, self.timeouts.sync_duties)
+            .await
+    }
 }
 
 /// Returns `Ok(response)` if the response is a `200 OK` response. Otherwise, creates an
@@ -1229,21 +1375,10 @@ async fn ok_or_error(response: Response) -> Result<Response, Error> {
     if status == StatusCode::OK {
         Ok(response)
     } else if let Ok(message) = response.json().await {
-        Err(Error::ServerMessage(message))
-    } else {
-        Err(Error::StatusCode(status))
-    }
-}
-
-/// Returns `Ok(response)` if the response is a `200 OK` response. Otherwise, creates an
-/// appropriate indexed error message.
-async fn ok_or_indexed_error(response: Response) -> Result<Response, Error> {
-    let status = response.status();
-
-    if status == StatusCode::OK {
-        Ok(response)
-    } else if let Ok(message) = response.json().await {
-        Err(Error::ServerIndexedMessage(message))
+        match message {
+            ResponseError::Message(message) => Err(Error::ServerMessage(message)),
+            ResponseError::Indexed(indexed) => Err(Error::ServerIndexedMessage(indexed)),
+        }
     } else {
         Err(Error::StatusCode(status))
     }

common/eth2/src/types.rs

@@ -10,6 +10,14 @@ use std::fmt;
 use std::str::{from_utf8, FromStr};
 pub use types::*;
 
+/// An API error serializable to JSON.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum Error {
+    Indexed(IndexedErrorMessage),
+    Message(ErrorMessage),
+}
+
 /// An API error serializable to JSON.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct ErrorMessage {
@@ -43,6 +51,30 @@ impl Failure {
     }
 }
 
+/// The version of a single API endpoint, e.g. the `v1` in `/eth/v1/beacon/blocks`.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct EndpointVersion(pub u64);
+
+impl FromStr for EndpointVersion {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if let Some(version_str) = s.strip_prefix('v') {
+            u64::from_str(version_str)
+                .map(EndpointVersion)
+                .map_err(|_| ())
+        } else {
+            Err(())
+        }
+    }
+}
+
+impl std::fmt::Display for EndpointVersion {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        write!(fmt, "v{}", self.0)
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct GenesisData {
     #[serde(with = "serde_utils::quoted_u64")]
@@ -179,6 +211,14 @@ impl<'a, T: Serialize> From<&'a T> for GenericResponseRef<'a, T> {
     }
 }
 
+#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
+// #[serde(bound = "T: Serialize + serde::de::DeserializeOwned")]
+pub struct ForkVersionedResponse<T> {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub version: Option<ForkName>,
+    pub data: T,
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
 pub struct RootData {
     pub root: Hash256,
@@ -378,6 +418,11 @@ pub struct CommitteesQuery {
     pub epoch: Option<Epoch>,
 }
 
+#[derive(Serialize, Deserialize)]
+pub struct SyncCommitteesQuery {
+    pub epoch: Option<Epoch>,
+}
+
 #[derive(Serialize, Deserialize)]
 pub struct AttestationPoolQuery {
     pub slot: Option<Slot>,
@@ -399,6 +444,20 @@ pub struct CommitteeData {
     pub validators: Vec<u64>,
 }
 
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct SyncCommitteeByValidatorIndices {
+    #[serde(with = "serde_utils::quoted_u64_vec")]
+    pub validators: Vec<u64>,
+    pub validator_aggregates: Vec<SyncSubcommittee>,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(transparent)]
+pub struct SyncSubcommittee {
+    #[serde(with = "serde_utils::quoted_u64_vec")]
+    pub indices: Vec<u64>,
+}
+
 #[derive(Serialize, Deserialize)]
 pub struct HeadersQuery {
     pub slot: Option<Slot>,

common/rest_types/Cargo.toml

@@ -1,27 +0,0 @@
-[package]
-name = "rest_types"
-version = "0.2.0"
-authors = ["Sigma Prime <contact@sigmaprime.io>"]
-edition = "2018"
-
-[dependencies]
-types = { path = "../../consensus/types" }
-eth2_ssz_derive = "0.1.0"
-eth2_ssz = "0.1.2"
-eth2_hashing = "0.1.0"
-tree_hash = "0.1.0"
-state_processing = { path = "../../consensus/state_processing" }
-bls = { path = "../../crypto/bls" }
-serde = { version = "1.0.110", features = ["derive"] }
-rayon = "1.3.0"
-hyper = "0.14.4"
-tokio = { version = "1.1.0", features = ["sync"] }
-environment = { path = "../../lighthouse/environment" }
-store = { path = "../../beacon_node/store" }
-beacon_chain = { path = "../../beacon_node/beacon_chain" }
-serde_json = "1.0.52"
-serde_yaml = "0.8.11"
-
-[target.'cfg(target_os = "linux")'.dependencies]
-psutil = "3.1.0"
-procinfo = "0.4.2"

consensus/types/Cargo.toml

@@ -50,6 +50,7 @@ superstruct = "0.2.0"
 serde_json = "1.0.58"
 criterion = "0.3.3"
 beacon_chain = { path = "../../beacon_node/beacon_chain" }
+eth2_interop_keypairs = { path = "../../common/eth2_interop_keypairs" }
 
 [features]
 default = ["sqlite", "legacy-arith"]

consensus/types/src/beacon_block.rs

@@ -149,6 +149,27 @@ impl<T: EthSpec> BeaconBlock<T> {
 }
 
 impl<'a, T: EthSpec> BeaconBlockRef<'a, T> {
+    /// Returns the name of the fork pertaining to `self`.
+    ///
+    /// Will return an `Err` if `self` has been instantiated to a variant conflicting with the fork
+    /// dictated by `self.slot()`.
+    pub fn fork_name(&self, spec: &ChainSpec) -> Result<ForkName, InconsistentFork> {
+        let fork_at_slot = spec.fork_name_at_slot::<T>(self.slot());
+        let object_fork = match self {
+            BeaconBlockRef::Base { .. } => ForkName::Base,
+            BeaconBlockRef::Altair { .. } => ForkName::Altair,
+        };
+
+        if fork_at_slot == object_fork {
+            Ok(object_fork)
+        } else {
+            Err(InconsistentFork {
+                fork_at_slot,
+                object_fork,
+            })
+        }
+    }
+
     /// Convenience accessor for the `body` as a `BeaconBlockBodyRef`.
     pub fn body(&self) -> BeaconBlockBodyRef<'a, T> {
         match self {

consensus/types/src/beacon_state.rs

@@ -837,6 +837,32 @@ impl<T: EthSpec> BeaconState<T> {
         })
     }
 
+    /// Get the sync committee duties for a list of validator indices.
+    ///
+    /// Will return a `SyncCommitteeNotKnown` error if the `epoch` is out of bounds with respect
+    /// to the current or next sync committee periods.
+    pub fn get_sync_committee_duties(
+        &self,
+        epoch: Epoch,
+        validator_indices: &[u64],
+        spec: &ChainSpec,
+    ) -> Result<Vec<Option<SyncDuty>>, Error> {
+        let sync_committee = self.get_built_sync_committee(epoch, spec)?;
+
+        validator_indices
+            .iter()
+            .map(|&validator_index| {
+                let pubkey = self.get_validator(validator_index as usize)?.pubkey;
+
+                Ok(SyncDuty::from_sync_committee(
+                    validator_index,
+                    pubkey,
+                    sync_committee,
+                ))
+            })
+            .collect()
+    }
+
     /// Get the canonical root of the `latest_block_header`, filling in its state root if necessary.
     ///
     /// It needs filling in on all slots where there isn't a skip.

consensus/types/src/chain_spec.rs

@@ -685,6 +685,8 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
+    use itertools::Itertools;
+    use safe_arith::SafeArith;
 
     #[test]
     fn test_mainnet_spec_can_be_constructed() {
@@ -745,6 +747,33 @@ mod tests {
             }
         }
     }
+
+    // Test that `next_fork_epoch` is consistent with the other functions.
+    #[test]
+    fn next_fork_epoch_consistency() {
+        type E = MainnetEthSpec;
+        let spec = ChainSpec::mainnet();
+
+        let mut last_fork_slot = Slot::new(0);
+
+        for (_, fork) in ForkName::list_all().into_iter().tuple_windows() {
+            if let Some(fork_epoch) = spec.fork_epoch(fork) {
+                last_fork_slot = fork_epoch.start_slot(E::slots_per_epoch());
+
+                // Fork is activated at non-zero epoch: check that `next_fork_epoch` returns
+                // the correct result.
+                if let Ok(prior_slot) = last_fork_slot.safe_sub(1) {
+                    let (next_fork, next_fork_epoch) =
+                        spec.next_fork_epoch::<E>(prior_slot).unwrap();
+                    assert_eq!(fork, next_fork);
+                    assert_eq!(spec.fork_epoch(fork).unwrap(), next_fork_epoch);
+                }
+            } else {
+                // Fork is not activated, check that `next_fork_epoch` returns `None`.
+                assert_eq!(spec.next_fork_epoch::<E>(last_fork_slot), None);
+            }
+        }
+    }
 }
 
 #[cfg(test)]

consensus/types/src/fork_name.rs

@@ -1,6 +1,12 @@
 use crate::{ChainSpec, Epoch};
+use serde_derive::{Deserialize, Serialize};
+use std::convert::TryFrom;
+use std::fmt::{self, Display, Formatter};
+use std::str::FromStr;
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[serde(try_from = "String")]
+#[serde(into = "String")]
 pub enum ForkName {
     Base,
     Altair,
@@ -48,7 +54,7 @@ impl ForkName {
     }
 }
 
-impl std::str::FromStr for ForkName {
+impl FromStr for ForkName {
     type Err = ();
 
     fn from_str(fork_name: &str) -> Result<Self, ()> {
@@ -60,6 +66,29 @@ impl std::str::FromStr for ForkName {
     }
 }
 
+impl Display for ForkName {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), fmt::Error> {
+        match self {
+            ForkName::Base => "phase0".fmt(f),
+            ForkName::Altair => "altair".fmt(f),
+        }
+    }
+}
+
+impl From<ForkName> for String {
+    fn from(fork: ForkName) -> String {
+        fork.to_string()
+    }
+}
+
+impl TryFrom<String> for ForkName {
+    type Error = String;
+
+    fn try_from(s: String) -> Result<Self, Self::Error> {
+        Self::from_str(&s).map_err(|()| format!("Invalid fork name: {}", s))
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct InconsistentFork {
     pub fork_at_slot: ForkName,

consensus/types/src/lib.rs

@@ -56,6 +56,7 @@ pub mod signed_contribution_and_proof;
 pub mod signed_voluntary_exit;
 pub mod signing_data;
 pub mod sync_committee_subscription;
+pub mod sync_duty;
 pub mod validator;
 pub mod validator_subscription;
 pub mod voluntary_exit;
@@ -137,9 +138,10 @@ pub use crate::subnet_id::SubnetId;
 pub use crate::sync_aggregate::SyncAggregate;
 pub use crate::sync_aggregator_selection_data::SyncAggregatorSelectionData;
 pub use crate::sync_committee::SyncCommittee;
-pub use crate::sync_committee_contribution::SyncCommitteeContribution;
+pub use crate::sync_committee_contribution::{SyncCommitteeContribution, SyncContributionData};
 pub use crate::sync_committee_message::SyncCommitteeMessage;
 pub use crate::sync_committee_subscription::SyncCommitteeSubscription;
+pub use crate::sync_duty::SyncDuty;
 pub use crate::sync_selection_proof::SyncSelectionProof;
 pub use crate::sync_subnet_id::SyncSubnetId;
 pub use crate::validator::Validator;

consensus/types/src/signed_beacon_block.rs

@@ -71,20 +71,7 @@ impl<E: EthSpec> SignedBeaconBlock<E> {
     /// Will return an `Err` if `self` has been instantiated to a variant conflicting with the fork
     /// dictated by `self.slot()`.
     pub fn fork_name(&self, spec: &ChainSpec) -> Result<ForkName, InconsistentFork> {
-        let fork_at_slot = spec.fork_name_at_slot::<E>(self.slot());
-        let object_fork = match self {
-            SignedBeaconBlock::Base { .. } => ForkName::Base,
-            SignedBeaconBlock::Altair { .. } => ForkName::Altair,
-        };
-
-        if fork_at_slot == object_fork {
-            Ok(object_fork)
-        } else {
-            Err(InconsistentFork {
-                fork_at_slot,
-                object_fork,
-            })
-        }
+        self.message().fork_name(spec)
     }
 
     /// SSZ decode.

consensus/types/src/sync_committee_contribution.rs

@@ -77,9 +77,9 @@ impl SignedRoot for Hash256 {}
 /// This is not in the spec, but useful for determining uniqueness of sync committee contributions
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
 pub struct SyncContributionData {
-    slot: Slot,
-    beacon_block_root: Hash256,
-    subcommittee_index: u64,
+    pub slot: Slot,
+    pub beacon_block_root: Hash256,
+    pub subcommittee_index: u64,
 }
 
 impl SyncContributionData {

consensus/types/src/sync_duty.rs

@@ -0,0 +1,83 @@
+use crate::{EthSpec, SyncCommittee, SyncSubnetId};
+use bls::PublicKeyBytes;
+use safe_arith::ArithError;
+use serde_derive::{Deserialize, Serialize};
+use std::collections::HashSet;
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct SyncDuty {
+    pub pubkey: PublicKeyBytes,
+    #[serde(with = "serde_utils::quoted_u64")]
+    pub validator_index: u64,
+    #[serde(with = "serde_utils::quoted_u64_vec")]
+    pub validator_sync_committee_indices: Vec<u64>,
+}
+
+impl SyncDuty {
+    /// Create a new `SyncDuty` from the list of validator indices in a sync committee.
+    pub fn from_sync_committee_indices(
+        validator_index: u64,
+        pubkey: PublicKeyBytes,
+        sync_committee_indices: &[usize],
+    ) -> Option<Self> {
+        // Positions of the `validator_index` within the committee.
+        let validator_sync_committee_indices = sync_committee_indices
+            .iter()
+            .enumerate()
+            .filter_map(|(i, &v)| {
+                if validator_index == v as u64 {
+                    Some(i as u64)
+                } else {
+                    None
+                }
+            })
+            .collect();
+        Self::new(validator_index, pubkey, validator_sync_committee_indices)
+    }
+
+    /// Create a new `SyncDuty` from a `SyncCommittee`, which contains the pubkeys but not the
+    /// indices.
+    pub fn from_sync_committee<T: EthSpec>(
+        validator_index: u64,
+        pubkey: PublicKeyBytes,
+        sync_committee: &SyncCommittee<T>,
+    ) -> Option<Self> {
+        let validator_sync_committee_indices = sync_committee
+            .pubkeys
+            .iter()
+            .enumerate()
+            .filter_map(|(i, committee_pubkey)| {
+                if &pubkey == committee_pubkey {
+                    Some(i as u64)
+                } else {
+                    None
+                }
+            })
+            .collect();
+        Self::new(validator_index, pubkey, validator_sync_committee_indices)
+    }
+
+    /// Create a duty if the `validator_sync_committee_indices` is non-empty.
+    fn new(
+        validator_index: u64,
+        pubkey: PublicKeyBytes,
+        validator_sync_committee_indices: Vec<u64>,
+    ) -> Option<Self> {
+        if !validator_sync_committee_indices.is_empty() {
+            Some(SyncDuty {
+                pubkey,
+                validator_index,
+                validator_sync_committee_indices,
+            })
+        } else {
+            None
+        }
+    }
+
+    /// Get the set of subnet IDs for this duty.
+    pub fn subnet_ids<E: EthSpec>(&self) -> Result<HashSet<SyncSubnetId>, ArithError> {
+        SyncSubnetId::compute_subnets_for_sync_committee::<E>(
+            &self.validator_sync_committee_indices,
+        )
+    }
+}

lcli/src/main.rs

@@ -41,7 +41,8 @@ fn main() {
                 .takes_value(true)
                 .required(true)
                 .possible_values(&["minimal", "mainnet"])
-                .default_value("mainnet"),
+                .default_value("mainnet")
+                .global(true),
         )
         .arg(
             Arg::with_name("testnet-dir")

scripts/local_testnet/beacon_node.sh

@@ -20,4 +20,5 @@ exec lighthouse \
 	--enr-udp-port $2 \
 	--enr-tcp-port $2 \
 	--port $2 \
-	--http-port $3
+	--http-port $3 \
+	--target-peers $((NODE_COUNT - 1))

scripts/local_testnet/setup.sh

@@ -9,6 +9,8 @@
 # $VALIDATOR_COUNT and $NODE_COUNT variables.
 #
 
+set -o nounset -o errexit -o pipefail
+
 source ./vars.env
 
 lcli \
@@ -20,10 +22,9 @@ lcli \
 NOW=`date +%s`
 GENESIS_TIME=`expr $NOW + $GENESIS_DELAY`
 
-
 lcli \
-	--spec mainnet \
 	new-testnet \
+	--spec $SPEC_PRESET \
 	--deposit-contract-address $DEPOSIT_CONTRACT_ADDRESS \
 	--testnet-dir $TESTNET_DIR \
 	--min-genesis-active-validator-count $GENESIS_VALIDATOR_COUNT \
@@ -50,8 +51,8 @@ echo Validators generated with keystore passwords at $DATADIR.
 echo "Building genesis state... (this might take a while)"
 
 lcli \
-	--spec mainnet \
 	interop-genesis \
+	--spec $SPEC_PRESET \
 	--genesis-time $GENESIS_TIME \
 	--testnet-dir $TESTNET_DIR \
 	$GENESIS_VALIDATOR_COUNT

scripts/local_testnet/vars.env

@@ -29,6 +29,9 @@ NETWORK_ID=4242
 # Hard fork configuration
 ALTAIR_FORK_EPOCH=18446744073709551615
 
+# Spec version (mainnet or minimal)
+SPEC_PRESET=mainnet
+
 # Seconds per Eth2 slot
 SECONDS_PER_SLOT=3
 

scripts/tests/vars.env

@@ -35,5 +35,8 @@ SECONDS_PER_SLOT=3
 # Seconds per Eth1 block
 SECONDS_PER_ETH1_BLOCK=1
 
+# Spec preset
+SPEC_PRESET=mainnet
+
 # Enable doppelganger detection
 VC_ARGS=" --enable-doppelganger-protection "

validator_client/Cargo.toml

@@ -64,6 +64,7 @@ scrypt = { version = "0.5.0", default-features = false }
 lighthouse_metrics = { path = "../common/lighthouse_metrics" }
 lazy_static = "1.4.0"
 fallback = { path = "../common/fallback" }
+itertools = "0.10.0"
 monitoring_api = { path = "../common/monitoring_api" }
 sensitive_url = { path = "../common/sensitive_url" }
 task_executor = { path = "../common/task_executor" }

validator_client/src/attestation_service.rs

@@ -18,7 +18,7 @@ use types::{
 };
 
 /// Builds an `AttestationService`.
-pub struct AttestationServiceBuilder<T, E: EthSpec> {
+pub struct AttestationServiceBuilder<T: SlotClock + 'static, E: EthSpec> {
     duties_service: Option<Arc<DutiesService<T, E>>>,
     validator_store: Option<Arc<ValidatorStore<T, E>>>,
     slot_clock: Option<T>,

validator_client/src/duties_service.rs

@@ -6,6 +6,8 @@
 //! The `DutiesService` is also responsible for sending events to the `BlockService` which trigger
 //! block production.
 
+mod sync;
+
 use crate::beacon_node_fallback::{BeaconNodeFallback, RequireSynced};
 use crate::{
     block_service::BlockServiceNotification,
@@ -20,6 +22,8 @@ use slog::{debug, error, info, warn, Logger};
 use slot_clock::SlotClock;
 use std::collections::{HashMap, HashSet};
 use std::sync::Arc;
+use sync::poll_sync_committee_duties;
+use sync::SyncDutiesMap;
 use tokio::{sync::mpsc::Sender, time::sleep};
 use types::{ChainSpec, Epoch, EthSpec, Hash256, PublicKeyBytes, SelectionProof, Slot};
 
@@ -40,6 +44,14 @@ pub enum Error {
     FailedToDownloadAttesters(String),
     FailedToProduceSelectionProof(ValidatorStoreError),
     InvalidModulo(ArithError),
+    Arith(ArithError),
+    SyncDutiesNotFound(u64),
+}
+
+impl From<ArithError> for Error {
+    fn from(e: ArithError) -> Self {
+        Self::Arith(e)
+    }
 }
 
 /// Neatly joins the server-generated `AttesterData` with the locally-generated `selection_proof`.
@@ -94,6 +106,8 @@ pub struct DutiesService<T, E: EthSpec> {
     /// Maps an epoch to all *local* proposers in this epoch. Notably, this does not contain
     /// proposals for any validators which are not registered locally.
     pub proposers: RwLock<ProposerMap>,
+    /// Map from validator index to sync committee duties.
+    pub sync_duties: SyncDutiesMap,
     /// Provides the canonical list of locally-managed validators.
     pub validator_store: Arc<ValidatorStore<T, E>>,
     /// Tracks the current slot.
@@ -302,6 +316,37 @@ pub fn start_update_service<T: SlotClock + 'static, E: EthSpec>(
         },
         "duties_service_attesters",
     );
+
+    // Spawn the task which keeps track of local sync committee duties.
+    let duties_service = core_duties_service.clone();
+    let log = core_duties_service.context.log().clone();
+    core_duties_service.context.executor.spawn(
+        async move {
+            loop {
+                if let Err(e) = poll_sync_committee_duties(&duties_service).await {
+                    error!(
+                       log,
+                       "Failed to poll sync committee duties";
+                       "error" => ?e
+                    );
+                }
+
+                // Wait until the next slot before polling again.
+                // This doesn't mean that the beacon node will get polled every slot
+                // as the sync duties service will return early if it deems it already has
+                // enough information.
+                if let Some(duration) = duties_service.slot_clock.duration_to_next_slot() {
+                    sleep(duration).await;
+                } else {
+                    // Just sleep for one slot if we are unable to read the system clock, this gives
+                    // us an opportunity for the clock to eventually come good.
+                    sleep(duties_service.slot_clock.slot_duration()).await;
+                    continue;
+                }
+            }
+        },
+        "duties_service_sync_committee",
+    );
 }
 
 /// Iterate through all the voting pubkeys in the `ValidatorStore` and attempt to learn any unknown

validator_client/src/duties_service/sync.rs

@@ -0,0 +1,599 @@
+use crate::{
+    doppelganger_service::DoppelgangerStatus,
+    duties_service::{DutiesService, Error},
+};
+use itertools::Itertools;
+use parking_lot::{MappedRwLockReadGuard, RwLock, RwLockReadGuard, RwLockWriteGuard};
+use slog::{crit, debug, info, warn};
+use slot_clock::SlotClock;
+use std::collections::{HashMap, HashSet};
+use std::sync::Arc;
+use types::{
+    ChainSpec, Epoch, EthSpec, PublicKeyBytes, Slot, SyncDuty, SyncSelectionProof, SyncSubnetId,
+};
+
+/// Number of epochs in advance to compute selection proofs.
+pub const AGGREGATION_PRE_COMPUTE_EPOCHS: u64 = 2;
+
+/// Top-level data-structure containing sync duty information.
+///
+/// This data is structured as a series of nested `HashMap`s wrapped in `RwLock`s. Fine-grained
+/// locking is used to provide maximum concurrency for the different services reading and writing.
+///
+/// Deadlocks are prevented by:
+///
+/// 1. Hierarchical locking. It is impossible to lock an inner lock (e.g. `validators`) without
+///    first locking its parent.
+/// 2. One-at-a-time locking. For the innermost locks on the aggregator duties, all of the functions
+///    in this file take care to only lock one validator at a time. We never hold a lock while
+///    trying to obtain another one (hence no lock ordering issues).
+pub struct SyncDutiesMap {
+    /// Map from sync committee period to duties for members of that sync committee.
+    committees: RwLock<HashMap<u64, CommitteeDuties>>,
+}
+
+/// Duties for a single sync committee period.
+#[derive(Default)]
+pub struct CommitteeDuties {
+    /// Map from validator index to validator duties.
+    ///
+    /// A `None` value indicates that the validator index is known *not* to be a member of the sync
+    /// committee, while a `Some` indicates a known member. An absent value indicates that the
+    /// validator index was not part of the set of local validators when the duties were fetched.
+    /// This allows us to track changes to the set of local validators.
+    validators: RwLock<HashMap<u64, Option<ValidatorDuties>>>,
+}
+
+/// Duties for a single validator.
+pub struct ValidatorDuties {
+    /// The sync duty: including validator sync committee indices & pubkey.
+    duty: SyncDuty,
+    /// The aggregator duties: cached selection proofs for upcoming epochs.
+    aggregation_duties: AggregatorDuties,
+}
+
+/// Aggregator duties for a single validator.
+pub struct AggregatorDuties {
+    /// The epoch up to which aggregation proofs have already been computed (inclusive).
+    pre_compute_epoch: RwLock<Option<Epoch>>,
+    /// Map from slot & subnet ID to proof that this validator is an aggregator.
+    ///
+    /// The slot is the slot at which the signed contribution and proof should be broadcast,
+    /// which is 1 less than the slot for which the `duty` was computed.
+    proofs: RwLock<HashMap<(Slot, SyncSubnetId), SyncSelectionProof>>,
+}
+
+/// Duties for multiple validators, for a single slot.
+///
+/// This type is returned to the sync service.
+pub struct SlotDuties {
+    /// List of duties for all sync committee members at this slot.
+    ///
+    /// Note: this is intentionally NOT split by subnet so that we only sign
+    /// one `SyncCommitteeMessage` per validator (recall a validator may be part of multiple
+    /// subnets).
+    pub duties: Vec<SyncDuty>,
+    /// Map from subnet ID to validator index and selection proof of each aggregator.
+    pub aggregators: HashMap<SyncSubnetId, Vec<(u64, PublicKeyBytes, SyncSelectionProof)>>,
+}
+
+impl Default for SyncDutiesMap {
+    fn default() -> Self {
+        Self {
+            committees: RwLock::new(HashMap::new()),
+        }
+    }
+}
+
+impl SyncDutiesMap {
+    /// Check if duties are already known for all of the given validators for `committee_period`.
+    fn all_duties_known(&self, committee_period: u64, validator_indices: &[u64]) -> bool {
+        self.committees
+            .read()
+            .get(&committee_period)
+            .map_or(false, |committee_duties| {
+                let validator_duties = committee_duties.validators.read();
+                validator_indices
+                    .iter()
+                    .all(|index| validator_duties.contains_key(index))
+            })
+    }
+
+    /// Prepare for pre-computation of selection proofs for `committee_period`.
+    ///
+    /// Return the epoch up to which proofs should be pre-computed, as well as a vec of
+    /// `(previous_pre_compute_epoch, sync_duty)` pairs for all validators which need to have proofs
+    /// computed. See `fill_in_aggregation_proofs` for the actual calculation.
+    fn prepare_for_aggregator_pre_compute(
+        &self,
+        committee_period: u64,
+        current_epoch: Epoch,
+        spec: &ChainSpec,
+    ) -> (Epoch, Vec<(Epoch, SyncDuty)>) {
+        let default_start_epoch =
+            std::cmp::max(current_epoch, first_epoch_of_period(committee_period, spec));
+        let pre_compute_epoch = std::cmp::min(
+            current_epoch + AGGREGATION_PRE_COMPUTE_EPOCHS,
+            last_epoch_of_period(committee_period, spec),
+        );
+
+        let pre_compute_duties = self.committees.read().get(&committee_period).map_or_else(
+            Vec::new,
+            |committee_duties| {
+                let validator_duties = committee_duties.validators.read();
+                validator_duties
+                    .values()
+                    .filter_map(|maybe_duty| {
+                        let duty = maybe_duty.as_ref()?;
+                        let old_pre_compute_epoch = duty
+                            .aggregation_duties
+                            .pre_compute_epoch
+                            .write()
+                            .replace(pre_compute_epoch);
+
+                        match old_pre_compute_epoch {
+                            // No proofs pre-computed previously, compute all from the start of
+                            // the period or the current epoch (whichever is later).
+                            None => Some((default_start_epoch, duty.duty.clone())),
+                            // Proofs computed up to `prev`, start from the subsequent epoch.
+                            Some(prev) if prev < pre_compute_epoch => {
+                                Some((prev + 1, duty.duty.clone()))
+                            }
+                            // Proofs already known, no need to compute.
+                            _ => None,
+                        }
+                    })
+                    .collect()
+            },
+        );
+        (pre_compute_epoch, pre_compute_duties)
+    }
+
+    fn get_or_create_committee_duties<'a, 'b>(
+        &'a self,
+        committee_period: u64,
+        validator_indices: impl IntoIterator<Item = &'b u64>,
+    ) -> MappedRwLockReadGuard<'a, CommitteeDuties> {
+        let mut committees_writer = self.committees.write();
+
+        committees_writer
+            .entry(committee_period)
+            .or_insert_with(CommitteeDuties::default)
+            .init(validator_indices);
+
+        // Return shared reference
+        RwLockReadGuard::map(
+            RwLockWriteGuard::downgrade(committees_writer),
+            |committees_reader| &committees_reader[&committee_period],
+        )
+    }
+
+    /// Get duties for all validators for the given `wall_clock_slot`.
+    ///
+    /// This is the entry-point for the sync committee service.
+    pub fn get_duties_for_slot<E: EthSpec>(
+        &self,
+        wall_clock_slot: Slot,
+        spec: &ChainSpec,
+    ) -> Option<SlotDuties> {
+        // Sync duties lag their assigned slot by 1
+        let duty_slot = wall_clock_slot + 1;
+
+        let sync_committee_period = duty_slot
+            .epoch(E::slots_per_epoch())
+            .sync_committee_period(spec)
+            .ok()?;
+
+        let committees_reader = self.committees.read();
+        let committee_duties = committees_reader.get(&sync_committee_period)?;
+
+        let mut duties = vec![];
+        let mut aggregators = HashMap::new();
+
+        committee_duties
+            .validators
+            .read()
+            .values()
+            // Filter out non-members & failed subnet IDs.
+            .filter_map(|opt_duties| {
+                let duty = opt_duties.as_ref()?;
+                let subnet_ids = duty.duty.subnet_ids::<E>().ok()?;
+                Some((duty, subnet_ids))
+            })
+            // Add duties for members to the vec of all duties, and aggregators to the
+            // aggregators map.
+            .for_each(|(validator_duty, subnet_ids)| {
+                duties.push(validator_duty.duty.clone());
+
+                let proofs = validator_duty.aggregation_duties.proofs.read();
+
+                for subnet_id in subnet_ids {
+                    if let Some(proof) = proofs.get(&(wall_clock_slot, subnet_id)) {
+                        aggregators.entry(subnet_id).or_insert_with(Vec::new).push((
+                            validator_duty.duty.validator_index,
+                            validator_duty.duty.pubkey,
+                            proof.clone(),
+                        ));
+                    }
+                }
+            });
+
+        Some(SlotDuties {
+            duties,
+            aggregators,
+        })
+    }
+
+    /// Prune duties for past sync committee periods from the map.
+    fn prune(&self, current_sync_committee_period: u64) {
+        self.committees
+            .write()
+            .retain(|period, _| *period >= current_sync_committee_period)
+    }
+}
+
+impl CommitteeDuties {
+    fn init<'b>(&mut self, validator_indices: impl IntoIterator<Item = &'b u64>) {
+        validator_indices.into_iter().for_each(|validator_index| {
+            self.validators
+                .get_mut()
+                .entry(*validator_index)
+                .or_insert(None);
+        })
+    }
+}
+
+impl ValidatorDuties {
+    fn new(duty: SyncDuty) -> Self {
+        Self {
+            duty,
+            aggregation_duties: AggregatorDuties {
+                pre_compute_epoch: RwLock::new(None),
+                proofs: RwLock::new(HashMap::new()),
+            },
+        }
+    }
+}
+
+/// Number of epochs to wait from the start of the period before actually fetching duties.
+fn epoch_offset(spec: &ChainSpec) -> u64 {
+    spec.epochs_per_sync_committee_period.as_u64() / 2
+}
+
+fn first_epoch_of_period(sync_committee_period: u64, spec: &ChainSpec) -> Epoch {
+    spec.epochs_per_sync_committee_period * sync_committee_period
+}
+
+fn last_epoch_of_period(sync_committee_period: u64, spec: &ChainSpec) -> Epoch {
+    first_epoch_of_period(sync_committee_period + 1, spec) - 1
+}
+
+pub async fn poll_sync_committee_duties<T: SlotClock + 'static, E: EthSpec>(
+    duties_service: &Arc<DutiesService<T, E>>,
+) -> Result<(), Error> {
+    let sync_duties = &duties_service.sync_duties;
+    let spec = &duties_service.spec;
+    let current_epoch = duties_service
+        .slot_clock
+        .now()
+        .ok_or(Error::UnableToReadSlotClock)?
+        .epoch(E::slots_per_epoch());
+
+    // If the Altair fork is yet to be activated, do not attempt to poll for duties.
+    if spec
+        .altair_fork_epoch
+        .map_or(true, |altair_epoch| current_epoch < altair_epoch)
+    {
+        return Ok(());
+    }
+
+    let current_sync_committee_period = current_epoch.sync_committee_period(spec)?;
+    let next_sync_committee_period = current_sync_committee_period + 1;
+
+    // Collect *all* pubkeys, even those undergoing doppelganger protection.
+    //
+    // Sync committee messages are not slashable and are currently excluded from doppelganger
+    // protection.
+    let local_pubkeys: HashSet<_> = duties_service
+        .validator_store
+        .voting_pubkeys(DoppelgangerStatus::ignored);
+
+    let local_indices = {
+        let mut local_indices = Vec::with_capacity(local_pubkeys.len());
+
+        let vals_ref = duties_service.validator_store.initialized_validators();
+        let vals = vals_ref.read();
+        for &pubkey in &local_pubkeys {
+            if let Some(validator_index) = vals.get_index(&pubkey) {
+                local_indices.push(validator_index)
+            }
+        }
+        local_indices
+    };
+
+    // If duties aren't known for the current period, poll for them.
+    if !sync_duties.all_duties_known(current_sync_committee_period, &local_indices) {
+        poll_sync_committee_duties_for_period(
+            duties_service,
+            &local_indices,
+            current_sync_committee_period,
+        )
+        .await?;
+
+        // Prune previous duties (we avoid doing this too often as it locks the whole map).
+        sync_duties.prune(current_sync_committee_period);
+    }
+
+    // Pre-compute aggregator selection proofs for the current period.
+    let (current_pre_compute_epoch, new_pre_compute_duties) = sync_duties
+        .prepare_for_aggregator_pre_compute(current_sync_committee_period, current_epoch, spec);
+
+    if !new_pre_compute_duties.is_empty() {
+        let sub_duties_service = duties_service.clone();
+        duties_service.context.executor.spawn_blocking(
+            move || {
+                fill_in_aggregation_proofs(
+                    sub_duties_service,
+                    &new_pre_compute_duties,
+                    current_sync_committee_period,
+                    current_epoch,
+                    current_pre_compute_epoch,
+                )
+            },
+            "duties_service_sync_selection_proofs",
+        );
+    }
+
+    // If we're past the point in the current period where we should determine duties for the next
+    // period and they are not yet known, then poll.
+    if current_epoch.as_u64() % spec.epochs_per_sync_committee_period.as_u64() >= epoch_offset(spec)
+        && !sync_duties.all_duties_known(next_sync_committee_period, &local_indices)
+    {
+        poll_sync_committee_duties_for_period(
+            duties_service,
+            &local_indices,
+            next_sync_committee_period,
+        )
+        .await?;
+
+        // Prune (this is the main code path for updating duties, so we should almost always hit
+        // this prune).
+        sync_duties.prune(current_sync_committee_period);
+    }
+
+    // Pre-compute aggregator selection proofs for the next period.
+    if (current_epoch + AGGREGATION_PRE_COMPUTE_EPOCHS).sync_committee_period(spec)?
+        == next_sync_committee_period
+    {
+        let (pre_compute_epoch, new_pre_compute_duties) = sync_duties
+            .prepare_for_aggregator_pre_compute(next_sync_committee_period, current_epoch, spec);
+
+        if !new_pre_compute_duties.is_empty() {
+            let sub_duties_service = duties_service.clone();
+            duties_service.context.executor.spawn_blocking(
+                move || {
+                    fill_in_aggregation_proofs(
+                        sub_duties_service,
+                        &new_pre_compute_duties,
+                        next_sync_committee_period,
+                        current_epoch,
+                        pre_compute_epoch,
+                    )
+                },
+                "duties_service_sync_selection_proofs",
+            );
+        }
+    }
+
+    Ok(())
+}
+
+pub async fn poll_sync_committee_duties_for_period<T: SlotClock + 'static, E: EthSpec>(
+    duties_service: &Arc<DutiesService<T, E>>,
+    local_indices: &[u64],
+    sync_committee_period: u64,
+) -> Result<(), Error> {
+    let spec = &duties_service.spec;
+    let log = duties_service.context.log();
+
+    debug!(
+        log,
+        "Fetching sync committee duties";
+        "sync_committee_period" => sync_committee_period,
+        "num_validators" => local_indices.len(),
+    );
+
+    let period_start_epoch = spec.epochs_per_sync_committee_period * sync_committee_period;
+
+    let duties_response = duties_service
+        .beacon_nodes
+        .first_success(duties_service.require_synced, |beacon_node| async move {
+            beacon_node
+                .post_validator_duties_sync(period_start_epoch, local_indices)
+                .await
+        })
+        .await;
+
+    let duties = match duties_response {
+        Ok(res) => res.data,
+        Err(e) => {
+            warn!(
+                log,
+                "Failed to download sync committee duties";
+                "sync_committee_period" => sync_committee_period,
+                "error" => %e,
+            );
+            return Ok(());
+        }
+    };
+
+    debug!(log, "Fetched sync duties from BN"; "count" => duties.len());
+
+    // Add duties to map.
+    let committee_duties = duties_service
+        .sync_duties
+        .get_or_create_committee_duties(sync_committee_period, local_indices);
+
+    let mut validator_writer = committee_duties.validators.write();
+    for duty in duties {
+        let validator_duties = validator_writer
+            .get_mut(&duty.validator_index)
+            .ok_or(Error::SyncDutiesNotFound(duty.validator_index))?;
+
+        let updated = validator_duties.as_ref().map_or(true, |existing_duties| {
+            let updated_due_to_reorg = existing_duties.duty.validator_sync_committee_indices
+                != duty.validator_sync_committee_indices;
+            if updated_due_to_reorg {
+                warn!(
+                    log,
+                    "Sync committee duties changed";
+                    "message" => "this could be due to a really long re-org, or a bug"
+                );
+            }
+            updated_due_to_reorg
+        });
+
+        if updated {
+            info!(
+                log,
+                "Validator in sync committee";
+                "validator_index" => duty.validator_index,
+                "sync_committee_period" => sync_committee_period,
+            );
+
+            *validator_duties = Some(ValidatorDuties::new(duty));
+        }
+    }
+
+    Ok(())
+}
+
+pub fn fill_in_aggregation_proofs<T: SlotClock + 'static, E: EthSpec>(
+    duties_service: Arc<DutiesService<T, E>>,
+    pre_compute_duties: &[(Epoch, SyncDuty)],
+    sync_committee_period: u64,
+    current_epoch: Epoch,
+    pre_compute_epoch: Epoch,
+) {
+    let log = duties_service.context.log();
+
+    debug!(
+        log,
+        "Calculating sync selection proofs";
+        "period" => sync_committee_period,
+        "current_epoch" => current_epoch,
+        "pre_compute_epoch" => pre_compute_epoch
+    );
+
+    // Generate selection proofs for each validator at each slot, one epoch at a time.
+    for epoch in (current_epoch.as_u64()..=pre_compute_epoch.as_u64()).map(Epoch::new) {
+        // Generate proofs.
+        let validator_proofs: Vec<(u64, Vec<_>)> = pre_compute_duties
+            .iter()
+            .filter_map(|(validator_start_epoch, duty)| {
+                // Proofs are already known at this epoch for this validator.
+                if epoch < *validator_start_epoch {
+                    return None;
+                }
+
+                let subnet_ids = duty
+                    .subnet_ids::<E>()
+                    .map_err(|e| {
+                        crit!(
+                            log,
+                            "Arithmetic error computing subnet IDs";
+                            "error" => ?e,
+                        );
+                    })
+                    .ok()?;
+
+                let proofs = epoch
+                    .slot_iter(E::slots_per_epoch())
+                    .cartesian_product(&subnet_ids)
+                    .filter_map(|(duty_slot, &subnet_id)| {
+                        // Construct proof for prior slot.
+                        let slot = duty_slot - 1;
+
+                        let proof = duties_service
+                            .validator_store
+                            .produce_sync_selection_proof(&duty.pubkey, slot, subnet_id)
+                            .map_err(|_| {
+                                warn!(
+                                    log,
+                                    "Pubkey missing when signing selection proof";
+                                    "pubkey" => ?duty.pubkey,
+                                    "slot" => slot,
+                                );
+                            })
+                            .ok()?;
+
+                        let is_aggregator = proof
+                            .is_aggregator::<E>()
+                            .map_err(|e| {
+                                warn!(
+                                    log,
+                                    "Error determining is_aggregator";
+                                    "pubkey" => ?duty.pubkey,
+                                    "slot" => slot,
+                                    "error" => ?e,
+                                );
+                            })
+                            .ok()?;
+
+                        if is_aggregator {
+                            debug!(
+                                log,
+                                "Validator is sync aggregator";
+                                "validator_index" => duty.validator_index,
+                                "slot" => slot,
+                                "subnet_id" => %subnet_id,
+                            );
+                            Some(((slot, subnet_id), proof))
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+
+                Some((duty.validator_index, proofs))
+            })
+            .collect();
+
+        // Add to global storage (we add regularly so the proofs can be used ASAP).
+        let sync_map = duties_service.sync_duties.committees.read();
+        let committee_duties = if let Some(duties) = sync_map.get(&sync_committee_period) {
+            duties
+        } else {
+            debug!(
+                log,
+                "Missing sync duties";
+                "period" => sync_committee_period,
+            );
+            continue;
+        };
+        let validators = committee_duties.validators.read();
+        let num_validators_updated = validator_proofs.len();
+
+        for (validator_index, proofs) in validator_proofs {
+            if let Some(Some(duty)) = validators.get(&validator_index) {
+                duty.aggregation_duties.proofs.write().extend(proofs);
+            } else {
+                debug!(
+                    log,
+                    "Missing sync duty to update";
+                    "validator_index" => validator_index,
+                    "period" => sync_committee_period,
+                );
+            }
+        }
+
+        if num_validators_updated > 0 {
+            debug!(
+                log,
+                "Finished computing sync selection proofs";
+                "epoch" => epoch,
+                "updated_validators" => num_validators_updated,
+            );
+        }
+    }
+}

validator_client/src/fork_service.rs

@@ -1,222 +0,0 @@
-use crate::beacon_node_fallback::{BeaconNodeFallback, RequireSynced};
-use crate::http_metrics::metrics;
-use environment::RuntimeContext;
-use eth2::types::StateId;
-use parking_lot::RwLock;
-use slog::{debug, trace};
-use slog::{error, Logger};
-use slot_clock::SlotClock;
-use std::ops::Deref;
-use std::sync::Arc;
-use tokio::time::{sleep, Duration};
-use types::{EthSpec, Fork};
-
-/// Delay this period of time after the slot starts. This allows the node to process the new slot.
-const TIME_DELAY_FROM_SLOT: Duration = Duration::from_millis(80);
-
-/// Builds a `ForkService`.
-pub struct ForkServiceBuilder<T, E: EthSpec> {
-    fork: Option<Fork>,
-    slot_clock: Option<T>,
-    beacon_nodes: Option<Arc<BeaconNodeFallback<T, E>>>,
-    log: Option<Logger>,
-}
-
-impl<T: SlotClock + 'static, E: EthSpec> ForkServiceBuilder<T, E> {
-    pub fn new() -> Self {
-        Self {
-            fork: None,
-            slot_clock: None,
-            beacon_nodes: None,
-            log: None,
-        }
-    }
-
-    pub fn fork(mut self, fork: Fork) -> Self {
-        self.fork = Some(fork);
-        self
-    }
-
-    pub fn slot_clock(mut self, slot_clock: T) -> Self {
-        self.slot_clock = Some(slot_clock);
-        self
-    }
-
-    pub fn beacon_nodes(mut self, beacon_nodes: Arc<BeaconNodeFallback<T, E>>) -> Self {
-        self.beacon_nodes = Some(beacon_nodes);
-        self
-    }
-
-    pub fn log(mut self, log: Logger) -> Self {
-        self.log = Some(log);
-        self
-    }
-
-    pub fn build(self) -> Result<ForkService<T, E>, String> {
-        Ok(ForkService {
-            inner: Arc::new(Inner {
-                fork: RwLock::new(self.fork.ok_or("Cannot build ForkService without fork")?),
-                slot_clock: self
-                    .slot_clock
-                    .ok_or("Cannot build ForkService without slot_clock")?,
-                beacon_nodes: self
-                    .beacon_nodes
-                    .ok_or("Cannot build ForkService without beacon_node")?,
-                log: self
-                    .log
-                    .ok_or("Cannot build ForkService without logger")?
-                    .clone(),
-            }),
-        })
-    }
-}
-
-#[cfg(test)]
-#[allow(dead_code)]
-impl<E: EthSpec> ForkServiceBuilder<slot_clock::TestingSlotClock, E> {
-    pub fn testing_only(spec: types::ChainSpec, log: Logger) -> Self {
-        use crate::beacon_node_fallback::CandidateBeaconNode;
-
-        let slot_clock = slot_clock::TestingSlotClock::new(
-            types::Slot::new(0),
-            std::time::Duration::from_secs(42),
-            std::time::Duration::from_secs(42),
-        );
-        let candidates = vec![CandidateBeaconNode::new(eth2::BeaconNodeHttpClient::new(
-            sensitive_url::SensitiveUrl::parse("http://127.0.0.1").unwrap(),
-            eth2::Timeouts::set_all(Duration::from_secs(12)),
-        ))];
-        let mut beacon_nodes = BeaconNodeFallback::new(candidates, spec, log.clone());
-        beacon_nodes.set_slot_clock(slot_clock);
-
-        Self {
-            fork: Some(types::Fork::default()),
-            slot_clock: Some(slot_clock::TestingSlotClock::new(
-                types::Slot::new(0),
-                std::time::Duration::from_secs(42),
-                std::time::Duration::from_secs(42),
-            )),
-            beacon_nodes: Some(Arc::new(beacon_nodes)),
-            log: Some(log),
-        }
-    }
-}
-
-/// Helper to minimise `Arc` usage.
-pub struct Inner<T, E: EthSpec> {
-    fork: RwLock<Fork>,
-    beacon_nodes: Arc<BeaconNodeFallback<T, E>>,
-    log: Logger,
-    slot_clock: T,
-}
-
-/// Attempts to download the `Fork` struct from the beacon node at the start of each epoch.
-pub struct ForkService<T, E: EthSpec> {
-    inner: Arc<Inner<T, E>>,
-}
-
-impl<T, E: EthSpec> Clone for ForkService<T, E> {
-    fn clone(&self) -> Self {
-        Self {
-            inner: self.inner.clone(),
-        }
-    }
-}
-
-impl<T, E: EthSpec> Deref for ForkService<T, E> {
-    type Target = Inner<T, E>;
-
-    fn deref(&self) -> &Self::Target {
-        self.inner.deref()
-    }
-}
-
-impl<T: SlotClock + 'static, E: EthSpec> ForkService<T, E> {
-    /// Returns the last fork downloaded from the beacon node, if any.
-    pub fn fork(&self) -> Fork {
-        *self.fork.read()
-    }
-
-    /// Returns the slot clock.
-    pub fn slot_clock(&self) -> T {
-        self.slot_clock.clone()
-    }
-
-    /// Starts the service that periodically polls for the `Fork`.
-    pub fn start_update_service(self, context: &RuntimeContext<E>) -> Result<(), String> {
-        // Run an immediate update before starting the updater service.
-        context
-            .executor
-            .spawn_ignoring_error(self.clone().do_update(), "fork service update");
-
-        let executor = context.executor.clone();
-        let log = context.log().clone();
-        let spec = E::default_spec();
-
-        let interval_fut = async move {
-            loop {
-                // Run this poll before the wait, this should hopefully download the fork before the
-                // other services need them.
-                self.clone().do_update().await.ok();
-
-                if let Some(duration_to_next_epoch) =
-                    self.slot_clock.duration_to_next_epoch(E::slots_per_epoch())
-                {
-                    sleep(duration_to_next_epoch + TIME_DELAY_FROM_SLOT).await;
-                } else {
-                    error!(log, "Failed to read slot clock");
-                    // If we can't read the slot clock, just wait another slot.
-                    sleep(Duration::from_secs(spec.seconds_per_slot)).await;
-                    continue;
-                }
-            }
-        };
-
-        executor.spawn(interval_fut, "fork_service");
-
-        Ok(())
-    }
-
-    /// Attempts to download the `Fork` from the server.
-    async fn do_update(self) -> Result<(), ()> {
-        let _timer =
-            metrics::start_timer_vec(&metrics::FORK_SERVICE_TIMES, &[metrics::FULL_UPDATE]);
-
-        let log = &self.log;
-        let fork = self
-            .inner
-            .beacon_nodes
-            .first_success(RequireSynced::No, |beacon_node| async move {
-                beacon_node
-                    .get_beacon_states_fork(StateId::Head)
-                    .await
-                    .map_err(|e| {
-                        trace!(
-                            log,
-                            "Fork update failed";
-                            "error" => format!("Error retrieving fork: {:?}", e)
-                        )
-                    })?
-                    .ok_or_else(|| {
-                        trace!(
-                            log,
-                            "Fork update failed";
-                            "error" => "The beacon head fork is unknown"
-                        )
-                    })
-                    .map(|result| result.data)
-            })
-            .await
-            .map_err(|_| ())?;
-
-        if *(self.fork.read()) != fork {
-            *(self.fork.write()) = fork;
-        }
-
-        debug!(self.log, "Fork update success");
-
-        // Returning an error will stop the interval. This is not desired, a single failure
-        // should not stop all future attempts.
-        Ok(())
-    }
-}

validator_client/src/http_api/tests.rs

@@ -4,7 +4,7 @@
 use crate::doppelganger_service::DoppelgangerService;
 use crate::{
     http_api::{ApiSecret, Config as HttpConfig, Context},
-    Config, ForkServiceBuilder, InitializedValidators, ValidatorDefinitions, ValidatorStore,
+    Config, InitializedValidators, ValidatorDefinitions, ValidatorStore,
 };
 use account_utils::{
     eth2_wallet::WalletBuilder, mnemonic_from_phrase, random_mnemonic, random_password,
@@ -17,10 +17,11 @@ use eth2_keystore::KeystoreBuilder;
 use parking_lot::RwLock;
 use sensitive_url::SensitiveUrl;
 use slashing_protection::{SlashingDatabase, SLASHING_PROTECTION_FILENAME};
-use slot_clock::TestingSlotClock;
+use slot_clock::{SlotClock, TestingSlotClock};
 use std::marker::PhantomData;
 use std::net::Ipv4Addr;
 use std::sync::Arc;
+use std::time::Duration;
 use tempfile::{tempdir, TempDir};
 use tokio::runtime::Runtime;
 use tokio::sync::oneshot;
@@ -73,20 +74,19 @@ impl ApiTester {
 
         let spec = E::default_spec();
 
-        let fork_service = ForkServiceBuilder::testing_only(spec.clone(), log.clone())
-            .build()
-            .unwrap();
-
         let slashing_db_path = config.validator_dir.join(SLASHING_PROTECTION_FILENAME);
         let slashing_protection = SlashingDatabase::open_or_create(&slashing_db_path).unwrap();
 
-        let validator_store: ValidatorStore<TestingSlotClock, E> = ValidatorStore::new(
+        let slot_clock =
+            TestingSlotClock::new(Slot::new(0), Duration::from_secs(0), Duration::from_secs(1));
+
+        let validator_store = ValidatorStore::<_, E>::new(
             initialized_validators,
             slashing_protection,
             Hash256::repeat_byte(42),
             spec,
-            fork_service.clone(),
             Some(Arc::new(DoppelgangerService::new(log.clone()))),
+            slot_clock,
             log.clone(),
         );
 
@@ -96,7 +96,7 @@ impl ApiTester {
 
         let initialized_validators = validator_store.initialized_validators();
 
-        let context: Arc<Context<TestingSlotClock, E>> = Arc::new(Context {
+        let context = Arc::new(Context {
             runtime,
             api_secret,
             validator_dir: Some(validator_dir.path().into()),

validator_client/src/http_metrics/metrics.rs

@@ -67,16 +67,26 @@ lazy_static::lazy_static! {
         "Total count of attempted SelectionProof signings",
         &["status"]
     );
+    pub static ref SIGNED_SYNC_COMMITTEE_MESSAGES_TOTAL: Result<IntCounterVec> = try_create_int_counter_vec(
+        "vc_signed_sync_committee_messages_total",
+        "Total count of attempted SyncCommitteeMessage signings",
+        &["status"]
+    );
+    pub static ref SIGNED_SYNC_COMMITTEE_CONTRIBUTIONS_TOTAL: Result<IntCounterVec> = try_create_int_counter_vec(
+        "vc_signed_sync_committee_contributions_total",
+        "Total count of attempted ContributionAndProof signings",
+        &["status"]
+    );
+    pub static ref SIGNED_SYNC_SELECTION_PROOFS_TOTAL: Result<IntCounterVec> = try_create_int_counter_vec(
+        "vc_signed_sync_selection_proofs_total",
+        "Total count of attempted SyncSelectionProof signings",
+        &["status"]
+    );
     pub static ref DUTIES_SERVICE_TIMES: Result<HistogramVec> = try_create_histogram_vec(
         "vc_duties_service_task_times_seconds",
         "Duration to perform duties service tasks",
         &["task"]
     );
-    pub static ref FORK_SERVICE_TIMES: Result<HistogramVec> = try_create_histogram_vec(
-        "vc_fork_service_task_times_seconds",
-        "Duration to perform fork service tasks",
-        &["task"]
-    );
     pub static ref ATTESTATION_SERVICE_TIMES: Result<HistogramVec> = try_create_histogram_vec(
         "vc_attestation_service_task_times_seconds",
         "Duration to perform attestation service tasks",

validator_client/src/lib.rs

@@ -5,12 +5,12 @@ mod check_synced;
 mod cli;
 mod config;
 mod duties_service;
-mod fork_service;
 mod graffiti_file;
 mod http_metrics;
 mod initialized_validators;
 mod key_cache;
 mod notifier;
+mod sync_committee_service;
 mod validator_store;
 
 mod doppelganger_service;
@@ -31,9 +31,7 @@ use block_service::{BlockService, BlockServiceBuilder};
 use clap::ArgMatches;
 use duties_service::DutiesService;
 use environment::RuntimeContext;
-use eth2::types::StateId;
 use eth2::{reqwest::ClientBuilder, BeaconNodeHttpClient, StatusCode, Timeouts};
-use fork_service::{ForkService, ForkServiceBuilder};
 use http_api::ApiSecret;
 use initialized_validators::InitializedValidators;
 use notifier::spawn_notifier;
@@ -46,11 +44,12 @@ use std::marker::PhantomData;
 use std::net::SocketAddr;
 use std::sync::Arc;
 use std::time::{SystemTime, UNIX_EPOCH};
+use sync_committee_service::SyncCommitteeService;
 use tokio::{
     sync::mpsc,
     time::{sleep, Duration},
 };
-use types::{EthSpec, Fork, Hash256};
+use types::{EthSpec, Hash256};
 use validator_store::ValidatorStore;
 
 /// The interval between attempts to contact the beacon node during startup.
@@ -66,6 +65,7 @@ const HTTP_ATTESTER_DUTIES_TIMEOUT_QUOTIENT: u32 = 4;
 const HTTP_LIVENESS_TIMEOUT_QUOTIENT: u32 = 4;
 const HTTP_PROPOSAL_TIMEOUT_QUOTIENT: u32 = 2;
 const HTTP_PROPOSER_DUTIES_TIMEOUT_QUOTIENT: u32 = 4;
+const HTTP_SYNC_DUTIES_TIMEOUT_QUOTIENT: u32 = 4;
 
 const DOPPELGANGER_SERVICE_NAME: &str = "doppelganger";
 
@@ -73,9 +73,9 @@ const DOPPELGANGER_SERVICE_NAME: &str = "doppelganger";
 pub struct ProductionValidatorClient<T: EthSpec> {
     context: RuntimeContext<T>,
     duties_service: Arc<DutiesService<SystemTimeSlotClock, T>>,
-    fork_service: ForkService<SystemTimeSlotClock, T>,
     block_service: BlockService<SystemTimeSlotClock, T>,
     attestation_service: AttestationService<SystemTimeSlotClock, T>,
+    sync_committee_service: SyncCommitteeService<SystemTimeSlotClock, T>,
     doppelganger_service: Option<Arc<DoppelgangerService>>,
     validator_store: Arc<ValidatorStore<SystemTimeSlotClock, T>>,
     http_api_listen_addr: Option<SocketAddr>,
@@ -263,6 +263,7 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
                         liveness: slot_duration / HTTP_LIVENESS_TIMEOUT_QUOTIENT,
                         proposal: slot_duration / HTTP_PROPOSAL_TIMEOUT_QUOTIENT,
                         proposer_duties: slot_duration / HTTP_PROPOSER_DUTIES_TIMEOUT_QUOTIENT,
+                        sync_duties: slot_duration / HTTP_SYNC_DUTIES_TIMEOUT_QUOTIENT,
                     }
                 } else {
                     Timeouts::set_all(slot_duration)
@@ -293,7 +294,7 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
             BeaconNodeFallback::new(candidates, context.eth2_config.spec.clone(), log.clone());
 
         // Perform some potentially long-running initialization tasks.
-        let (genesis_time, genesis_validators_root, fork) = tokio::select! {
+        let (genesis_time, genesis_validators_root) = tokio::select! {
             tuple = init_from_beacon_node(&beacon_nodes, &context) => tuple?,
             () = context.executor.exit() => return Err("Shutting down".to_string())
         };
@@ -313,13 +314,6 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
         let beacon_nodes = Arc::new(beacon_nodes);
         start_fallback_updater_service(context.clone(), beacon_nodes.clone())?;
 
-        let fork_service = ForkServiceBuilder::new()
-            .fork(fork)
-            .slot_clock(slot_clock.clone())
-            .beacon_nodes(beacon_nodes.clone())
-            .log(log.clone())
-            .build()?;
-
         let doppelganger_service = if config.enable_doppelganger_protection {
             Some(Arc::new(DoppelgangerService::new(
                 context
@@ -331,16 +325,15 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
             None
         };
 
-        let validator_store: Arc<ValidatorStore<SystemTimeSlotClock, T>> =
-            Arc::new(ValidatorStore::new(
-                validators,
-                slashing_protection,
-                genesis_validators_root,
-                context.eth2_config.spec.clone(),
-                fork_service.clone(),
-                doppelganger_service.clone(),
-                log.clone(),
-            ));
+        let validator_store = Arc::new(ValidatorStore::new(
+            validators,
+            slashing_protection,
+            genesis_validators_root,
+            context.eth2_config.spec.clone(),
+            doppelganger_service.clone(),
+            slot_clock.clone(),
+            log.clone(),
+        ));
 
         info!(
             log,
@@ -359,6 +352,7 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
         let duties_service = Arc::new(DutiesService {
             attesters: <_>::default(),
             proposers: <_>::default(),
+            sync_duties: <_>::default(),
             slot_clock: slot_clock.clone(),
             beacon_nodes: beacon_nodes.clone(),
             validator_store: validator_store.clone(),
@@ -394,6 +388,14 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
             .runtime_context(context.service_context("attestation".into()))
             .build()?;
 
+        let sync_committee_service = SyncCommitteeService::new(
+            duties_service.clone(),
+            validator_store.clone(),
+            slot_clock,
+            beacon_nodes.clone(),
+            context.service_context("sync_committee".into()),
+        );
+
         // Wait until genesis has occured.
         //
         // It seems most sensible to move this into the `start_service` function, but I'm caution
@@ -406,9 +408,9 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
         Ok(Self {
             context,
             duties_service,
-            fork_service,
             block_service,
             attestation_service,
+            sync_committee_service,
             doppelganger_service,
             validator_store,
             config,
@@ -427,11 +429,6 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
 
         duties_service::start_update_service(self.duties_service.clone(), block_service_tx);
 
-        self.fork_service
-            .clone()
-            .start_update_service(&self.context)
-            .map_err(|e| format!("Unable to start fork service: {}", e))?;
-
         self.block_service
             .clone()
             .start_update_service(block_service_rx)
@@ -442,6 +439,11 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
             .start_update_service(&self.context.eth2_config.spec)
             .map_err(|e| format!("Unable to start attestation service: {}", e))?;
 
+        self.sync_committee_service
+            .clone()
+            .start_update_service(&self.context.eth2_config.spec)
+            .map_err(|e| format!("Unable to start sync committee service: {}", e))?;
+
         if let Some(doppelganger_service) = self.doppelganger_service.clone() {
             DoppelgangerService::start_update_service(
                 doppelganger_service,
@@ -461,7 +463,7 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
         let api_secret = ApiSecret::create_or_open(&self.config.validator_dir)?;
 
         self.http_api_listen_addr = if self.config.http_api.enabled {
-            let ctx: Arc<http_api::Context<SystemTimeSlotClock, T>> = Arc::new(http_api::Context {
+            let ctx = Arc::new(http_api::Context {
                 runtime: self.context.executor.runtime(),
                 api_secret,
                 validator_store: Some(self.validator_store.clone()),
@@ -495,7 +497,7 @@ impl<T: EthSpec> ProductionValidatorClient<T> {
 async fn init_from_beacon_node<E: EthSpec>(
     beacon_nodes: &BeaconNodeFallback<SystemTimeSlotClock, E>,
     context: &RuntimeContext<E>,
-) -> Result<(u64, Hash256, Fork), String> {
+) -> Result<(u64, Hash256), String> {
     loop {
         beacon_nodes.update_unready_candidates().await;
         let num_available = beacon_nodes.num_available().await;
@@ -554,33 +556,7 @@ async fn init_from_beacon_node<E: EthSpec>(
         sleep(RETRY_DELAY).await;
     };
 
-    let fork = loop {
-        match beacon_nodes
-            .first_success(RequireSynced::No, |node| async move {
-                node.get_beacon_states_fork(StateId::Head).await
-            })
-            .await
-        {
-            Ok(Some(fork)) => break fork.data,
-            Ok(None) => {
-                info!(
-                    context.log(),
-                    "Failed to get fork, state not found";
-                );
-            }
-            Err(errors) => {
-                error!(
-                    context.log(),
-                    "Failed to get fork";
-                    "error" => %errors
-                );
-            }
-        }
-
-        sleep(RETRY_DELAY).await;
-    };
-
-    Ok((genesis.genesis_time, genesis.genesis_validators_root, fork))
+    Ok((genesis.genesis_time, genesis.genesis_validators_root))
 }
 
 async fn wait_for_genesis<E: EthSpec>(

validator_client/src/sync_committee_service.rs

@@ -0,0 +1,537 @@
+use crate::beacon_node_fallback::{BeaconNodeFallback, RequireSynced};
+use crate::{duties_service::DutiesService, validator_store::ValidatorStore};
+use environment::RuntimeContext;
+use eth2::types::BlockId;
+use futures::future::FutureExt;
+use slog::{crit, debug, error, info, trace, warn};
+use slot_clock::SlotClock;
+use std::collections::HashMap;
+use std::ops::Deref;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
+use tokio::time::{sleep, sleep_until, Duration, Instant};
+use types::{
+    ChainSpec, EthSpec, Hash256, PublicKeyBytes, Slot, SyncCommitteeSubscription,
+    SyncContributionData, SyncDuty, SyncSelectionProof, SyncSubnetId,
+};
+
+pub const SUBSCRIPTION_LOOKAHEAD_EPOCHS: u64 = 4;
+
+pub struct SyncCommitteeService<T: SlotClock + 'static, E: EthSpec> {
+    inner: Arc<Inner<T, E>>,
+}
+
+impl<T: SlotClock + 'static, E: EthSpec> Clone for SyncCommitteeService<T, E> {
+    fn clone(&self) -> Self {
+        Self {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
+impl<T: SlotClock + 'static, E: EthSpec> Deref for SyncCommitteeService<T, E> {
+    type Target = Inner<T, E>;
+
+    fn deref(&self) -> &Self::Target {
+        self.inner.deref()
+    }
+}
+
+pub struct Inner<T: SlotClock + 'static, E: EthSpec> {
+    duties_service: Arc<DutiesService<T, E>>,
+    validator_store: Arc<ValidatorStore<T, E>>,
+    slot_clock: T,
+    beacon_nodes: Arc<BeaconNodeFallback<T, E>>,
+    context: RuntimeContext<E>,
+    /// Boolean to track whether the service has posted subscriptions to the BN at least once.
+    ///
+    /// This acts as a latch that fires once upon start-up, and then never again.
+    first_subscription_done: AtomicBool,
+}
+
+impl<T: SlotClock + 'static, E: EthSpec> SyncCommitteeService<T, E> {
+    pub fn new(
+        duties_service: Arc<DutiesService<T, E>>,
+        validator_store: Arc<ValidatorStore<T, E>>,
+        slot_clock: T,
+        beacon_nodes: Arc<BeaconNodeFallback<T, E>>,
+        context: RuntimeContext<E>,
+    ) -> Self {
+        Self {
+            inner: Arc::new(Inner {
+                duties_service,
+                validator_store,
+                slot_clock,
+                beacon_nodes,
+                context,
+                first_subscription_done: AtomicBool::new(false),
+            }),
+        }
+    }
+
+    /// Check if the Altair fork has been activated and therefore sync duties should be performed.
+    ///
+    /// Slot clock errors are mapped to `false`.
+    fn altair_fork_activated(&self) -> bool {
+        self.duties_service
+            .spec
+            .altair_fork_epoch
+            .and_then(|fork_epoch| {
+                let current_epoch = self.slot_clock.now()?.epoch(E::slots_per_epoch());
+                Some(current_epoch >= fork_epoch)
+            })
+            .unwrap_or(false)
+    }
+
+    pub fn start_update_service(self, spec: &ChainSpec) -> Result<(), String> {
+        let log = self.context.log().clone();
+        let slot_duration = Duration::from_secs(spec.seconds_per_slot);
+        let duration_to_next_slot = self
+            .slot_clock
+            .duration_to_next_slot()
+            .ok_or("Unable to determine duration to next slot")?;
+
+        info!(
+            log,
+            "Sync committee service started";
+            "next_update_millis" => duration_to_next_slot.as_millis()
+        );
+
+        let executor = self.context.executor.clone();
+
+        let interval_fut = async move {
+            loop {
+                if let Some(duration_to_next_slot) = self.slot_clock.duration_to_next_slot() {
+                    // Wait for contribution broadcast interval 1/3 of the way through the slot.
+                    let log = self.context.log();
+                    sleep(duration_to_next_slot + slot_duration / 3).await;
+
+                    // Do nothing if the Altair fork has not yet occurred.
+                    if !self.altair_fork_activated() {
+                        continue;
+                    }
+
+                    if let Err(e) = self.spawn_contribution_tasks(slot_duration).await {
+                        crit!(
+                            log,
+                            "Failed to spawn sync contribution tasks";
+                            "error" => e
+                        )
+                    } else {
+                        trace!(
+                            log,
+                            "Spawned sync contribution tasks";
+                        )
+                    }
+
+                    // Do subscriptions for future slots/epochs.
+                    self.spawn_subscription_tasks();
+                } else {
+                    error!(log, "Failed to read slot clock");
+                    // If we can't read the slot clock, just wait another slot.
+                    sleep(slot_duration).await;
+                }
+            }
+        };
+
+        executor.spawn(interval_fut, "sync_committee_service");
+        Ok(())
+    }
+
+    async fn spawn_contribution_tasks(&self, slot_duration: Duration) -> Result<(), String> {
+        let log = self.context.log().clone();
+        let slot = self.slot_clock.now().ok_or("Failed to read slot clock")?;
+        let duration_to_next_slot = self
+            .slot_clock
+            .duration_to_next_slot()
+            .ok_or("Unable to determine duration to next slot")?;
+
+        // If a validator needs to publish a sync aggregate, they must do so at 2/3
+        // through the slot. This delay triggers at this time
+        let aggregate_production_instant = Instant::now()
+            + duration_to_next_slot
+                .checked_sub(slot_duration / 3)
+                .unwrap_or_else(|| Duration::from_secs(0));
+
+        let slot_duties = self
+            .duties_service
+            .sync_duties
+            .get_duties_for_slot::<E>(slot, &self.duties_service.spec)
+            .ok_or_else(|| format!("Error fetching duties for slot {}", slot))?;
+
+        if slot_duties.duties.is_empty() {
+            debug!(
+                log,
+                "No local validators in current sync committee";
+                "slot" => slot,
+            );
+            return Ok(());
+        }
+
+        // Fetch block root for `SyncCommitteeContribution`.
+        let block_root = self
+            .beacon_nodes
+            .first_success(RequireSynced::Yes, |beacon_node| async move {
+                beacon_node.get_beacon_blocks_root(BlockId::Head).await
+            })
+            .await
+            .map_err(|e| e.to_string())?
+            .ok_or_else(|| format!("No block root found for slot {}", slot))?
+            .data
+            .root;
+
+        // Spawn one task to publish all of the sync committee signatures.
+        let validator_duties = slot_duties.duties;
+        self.inner.context.executor.spawn(
+            self.clone()
+                .publish_sync_committee_signatures(slot, block_root, validator_duties)
+                .map(|_| ()),
+            "sync_committee_signature_publish",
+        );
+
+        let aggregators = slot_duties.aggregators;
+        self.inner.context.executor.spawn(
+            self.clone()
+                .publish_sync_committee_aggregates(
+                    slot,
+                    block_root,
+                    aggregators,
+                    aggregate_production_instant,
+                )
+                .map(|_| ()),
+            "sync_committee_aggregate_publish",
+        );
+
+        Ok(())
+    }
+
+    /// Publish sync committee signatures.
+    async fn publish_sync_committee_signatures(
+        self,
+        slot: Slot,
+        beacon_block_root: Hash256,
+        validator_duties: Vec<SyncDuty>,
+    ) -> Result<(), ()> {
+        let log = self.context.log().clone();
+
+        let committee_signatures = validator_duties
+            .iter()
+            .filter_map(|duty| {
+                self.validator_store
+                    .produce_sync_committee_signature(
+                        slot,
+                        beacon_block_root,
+                        duty.validator_index,
+                        &duty.pubkey,
+                    )
+                    .map_err(|e| {
+                        crit!(
+                            log,
+                            "Failed to sign sync committee signature";
+                            "validator_index" => duty.validator_index,
+                            "slot" => slot,
+                            "error" => ?e,
+                        );
+                    })
+                    .ok()
+            })
+            .collect::<Vec<_>>();
+
+        let signatures_slice = &committee_signatures;
+
+        self.beacon_nodes
+            .first_success(RequireSynced::No, |beacon_node| async move {
+                beacon_node
+                    .post_beacon_pool_sync_committee_signatures(signatures_slice)
+                    .await
+            })
+            .await
+            .map_err(|e| {
+                error!(
+                    log,
+                    "Unable to publish sync committee messages";
+                    "slot" => slot,
+                    "error" => %e,
+                );
+            })?;
+
+        info!(
+            log,
+            "Successfully published sync committee messages";
+            "count" => committee_signatures.len(),
+            "head_block" => ?beacon_block_root,
+            "slot" => slot,
+        );
+
+        Ok(())
+    }
+
+    async fn publish_sync_committee_aggregates(
+        self,
+        slot: Slot,
+        beacon_block_root: Hash256,
+        aggregators: HashMap<SyncSubnetId, Vec<(u64, PublicKeyBytes, SyncSelectionProof)>>,
+        aggregate_instant: Instant,
+    ) {
+        for (subnet_id, subnet_aggregators) in aggregators {
+            let service = self.clone();
+            self.inner.context.executor.spawn(
+                service
+                    .publish_sync_committee_aggregate_for_subnet(
+                        slot,
+                        beacon_block_root,
+                        subnet_id,
+                        subnet_aggregators,
+                        aggregate_instant,
+                    )
+                    .map(|_| ()),
+                "sync_committee_aggregate_publish_subnet",
+            );
+        }
+    }
+
+    async fn publish_sync_committee_aggregate_for_subnet(
+        self,
+        slot: Slot,
+        beacon_block_root: Hash256,
+        subnet_id: SyncSubnetId,
+        subnet_aggregators: Vec<(u64, PublicKeyBytes, SyncSelectionProof)>,
+        aggregate_instant: Instant,
+    ) -> Result<(), ()> {
+        sleep_until(aggregate_instant).await;
+
+        let log = self.context.log();
+
+        let contribution = self
+            .beacon_nodes
+            .first_success(RequireSynced::No, |beacon_node| async move {
+                let sync_contribution_data = SyncContributionData {
+                    slot,
+                    beacon_block_root,
+                    subcommittee_index: subnet_id.into(),
+                };
+
+                beacon_node
+                    .get_validator_sync_committee_contribution::<E>(&sync_contribution_data)
+                    .await
+            })
+            .await
+            .map_err(|e| {
+                crit!(
+                    log,
+                    "Failed to produce sync contribution";
+                    "slot" => slot,
+                    "beacon_block_root" => ?beacon_block_root,
+                    "error" => %e,
+                )
+            })?
+            .ok_or_else(|| {
+                crit!(
+                    log,
+                    "No aggregate contribution found";
+                    "slot" => slot,
+                    "beacon_block_root" => ?beacon_block_root,
+                );
+            })?
+            .data;
+
+        // Make `SignedContributionAndProof`s
+        let signed_contributions = subnet_aggregators
+            .into_iter()
+            .filter_map(|(aggregator_index, aggregator_pk, selection_proof)| {
+                self.validator_store
+                    .produce_signed_contribution_and_proof(
+                        aggregator_index,
+                        &aggregator_pk,
+                        contribution.clone(),
+                        selection_proof,
+                    )
+                    .map_err(|e| {
+                        crit!(
+                            log,
+                            "Unable to sign sync committee contribution";
+                            "slot" => slot,
+                            "error" => ?e,
+                        );
+                    })
+                    .ok()
+            })
+            .collect::<Vec<_>>();
+
+        // Publish to the beacon node.
+        let signed_contributions_slice = &signed_contributions;
+        self.beacon_nodes
+            .first_success(RequireSynced::No, |beacon_node| async move {
+                beacon_node
+                    .post_validator_contribution_and_proofs(signed_contributions_slice)
+                    .await
+            })
+            .await
+            .map_err(|e| {
+                error!(
+                    log,
+                    "Unable to publish signed contributions and proofs";
+                    "slot" => slot,
+                    "error" => %e,
+                );
+            })?;
+
+        info!(
+            log,
+            "Successfully published sync contributions";
+            "subnet" => %subnet_id,
+            "beacon_block_root" => %beacon_block_root,
+            "num_signers" => contribution.aggregation_bits.num_set_bits(),
+            "slot" => slot,
+        );
+
+        Ok(())
+    }
+
+    fn spawn_subscription_tasks(&self) {
+        let service = self.clone();
+        let log = self.context.log().clone();
+        self.inner.context.executor.spawn(
+            async move {
+                service.publish_subscriptions().await.unwrap_or_else(|e| {
+                    error!(
+                        log,
+                        "Error publishing subscriptions";
+                        "error" => ?e,
+                    )
+                });
+            },
+            "sync_committee_subscription_publish",
+        );
+    }
+
+    async fn publish_subscriptions(self) -> Result<(), String> {
+        let log = self.context.log().clone();
+        let spec = &self.duties_service.spec;
+        let slot = self.slot_clock.now().ok_or("Failed to read slot clock")?;
+
+        let mut duty_slots = vec![];
+        let mut all_succeeded = true;
+
+        // At the start of every epoch during the current period, re-post the subscriptions
+        // to the beacon node. This covers the case where the BN has forgotten the subscriptions
+        // due to a restart, or where the VC has switched to a fallback BN.
+        let current_period = sync_period_of_slot::<E>(slot, spec)?;
+
+        if !self.first_subscription_done.load(Ordering::Relaxed)
+            || slot.as_u64() % E::slots_per_epoch() == 0
+        {
+            duty_slots.push((slot, current_period));
+        }
+
+        // Near the end of the current period, push subscriptions for the next period to the
+        // beacon node. We aggressively push every slot in the lead-up, as this is the main way
+        // that we want to ensure that the BN is subscribed (well in advance).
+        let lookahead_slot = slot + SUBSCRIPTION_LOOKAHEAD_EPOCHS * E::slots_per_epoch();
+
+        let lookahead_period = sync_period_of_slot::<E>(lookahead_slot, spec)?;
+
+        if lookahead_period > current_period {
+            duty_slots.push((lookahead_slot, lookahead_period));
+        }
+
+        if duty_slots.is_empty() {
+            return Ok(());
+        }
+
+        // Collect subscriptions.
+        let mut subscriptions = vec![];
+
+        for (duty_slot, sync_committee_period) in duty_slots {
+            debug!(
+                log,
+                "Fetching subscription duties";
+                "duty_slot" => duty_slot,
+                "current_slot" => slot,
+            );
+            match self
+                .duties_service
+                .sync_duties
+                .get_duties_for_slot::<E>(duty_slot, spec)
+            {
+                Some(duties) => subscriptions.extend(subscriptions_from_sync_duties(
+                    duties.duties,
+                    sync_committee_period,
+                    spec,
+                )),
+                None => {
+                    warn!(
+                        log,
+                        "Missing duties for subscription";
+                        "slot" => duty_slot,
+                    );
+                    all_succeeded = false;
+                }
+            }
+        }
+
+        // Post subscriptions to BN.
+        debug!(
+            log,
+            "Posting sync subscriptions to BN";
+            "count" => subscriptions.len(),
+        );
+        let subscriptions_slice = &subscriptions;
+
+        for subscription in subscriptions_slice {
+            debug!(
+                log,
+                "Subscription";
+                "validator_index" => subscription.validator_index,
+                "validator_sync_committee_indices" => ?subscription.sync_committee_indices,
+                "until_epoch" => subscription.until_epoch,
+            );
+        }
+
+        if let Err(e) = self
+            .beacon_nodes
+            .first_success(RequireSynced::No, |beacon_node| async move {
+                beacon_node
+                    .post_validator_sync_committee_subscriptions(subscriptions_slice)
+                    .await
+            })
+            .await
+        {
+            error!(
+                log,
+                "Unable to post sync committee subscriptions";
+                "slot" => slot,
+                "error" => %e,
+            );
+            all_succeeded = false;
+        }
+
+        // Disable first-subscription latch once all duties have succeeded once.
+        if all_succeeded {
+            self.first_subscription_done.store(true, Ordering::Relaxed);
+        }
+
+        Ok(())
+    }
+}
+
+fn sync_period_of_slot<E: EthSpec>(slot: Slot, spec: &ChainSpec) -> Result<u64, String> {
+    slot.epoch(E::slots_per_epoch())
+        .sync_committee_period(spec)
+        .map_err(|e| format!("Error computing sync period: {:?}", e))
+}
+
+fn subscriptions_from_sync_duties(
+    duties: Vec<SyncDuty>,
+    sync_committee_period: u64,
+    spec: &ChainSpec,
+) -> impl Iterator<Item = SyncCommitteeSubscription> {
+    let until_epoch = spec.epochs_per_sync_committee_period * (sync_committee_period + 1);
+    duties
+        .into_iter()
+        .map(move |duty| SyncCommitteeSubscription {
+            validator_index: duty.validator_index,
+            sync_committee_indices: duty.validator_sync_committee_indices,
+            until_epoch,
+        })
+}

validator_client/src/validator_store.rs

@@ -1,5 +1,5 @@
 use crate::{
-    doppelganger_service::DoppelgangerService, fork_service::ForkService, http_metrics::metrics,
+    doppelganger_service::DoppelgangerService, http_metrics::metrics,
     initialized_validators::InitializedValidators,
 };
 use account_utils::{validator_definitions::ValidatorDefinition, ZeroizeString};
@@ -8,12 +8,15 @@ use slashing_protection::{NotSafe, Safe, SlashingDatabase};
 use slog::{crit, error, info, warn, Logger};
 use slot_clock::SlotClock;
 use std::iter::FromIterator;
+use std::marker::PhantomData;
 use std::path::Path;
 use std::sync::Arc;
 use types::{
     attestation::Error as AttestationError, graffiti::GraffitiString, Attestation, BeaconBlock,
     ChainSpec, Domain, Epoch, EthSpec, Fork, Graffiti, Hash256, Keypair, PublicKeyBytes,
-    SelectionProof, Signature, SignedAggregateAndProof, SignedBeaconBlock, SignedRoot, Slot,
+    SelectionProof, Signature, SignedAggregateAndProof, SignedBeaconBlock,
+    SignedContributionAndProof, SignedRoot, Slot, SyncCommitteeContribution, SyncCommitteeMessage,
+    SyncSelectionProof, SyncSubnetId,
 };
 use validator_dir::ValidatorDir;
 
@@ -69,8 +72,8 @@ pub struct ValidatorStore<T, E: EthSpec> {
     spec: Arc<ChainSpec>,
     log: Logger,
     doppelganger_service: Option<Arc<DoppelgangerService>>,
-    fork_service: ForkService<T, E>,
     slot_clock: T,
+    _phantom: PhantomData<E>,
 }
 
 impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
@@ -79,8 +82,8 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         slashing_protection: SlashingDatabase,
         genesis_validators_root: Hash256,
         spec: ChainSpec,
-        fork_service: ForkService<T, E>,
         doppelganger_service: Option<Arc<DoppelgangerService>>,
+        slot_clock: T,
         log: Logger,
     ) -> Self {
         Self {
@@ -89,10 +92,10 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
             slashing_protection_last_prune: Arc::new(Mutex::new(Epoch::new(0))),
             genesis_validators_root,
             spec: Arc::new(spec),
-            log: log.clone(),
+            log,
             doppelganger_service,
-            slot_clock: fork_service.slot_clock(),
-            fork_service,
+            slot_clock,
+            _phantom: PhantomData,
         }
     }
 
@@ -253,8 +256,8 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         self.validators.read().num_enabled()
     }
 
-    fn fork(&self) -> Fork {
-        self.fork_service.fork()
+    fn fork(&self, epoch: Epoch) -> Fork {
+        self.spec.fork_at_epoch(epoch)
     }
 
     /// Runs `func`, providing it access to the `Keypair` corresponding to `validator_pubkey`.
@@ -301,7 +304,7 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         let domain = self.spec.get_domain(
             epoch,
             Domain::Randao,
-            &self.fork(),
+            &self.fork(epoch),
             self.genesis_validators_root,
         );
         let message = epoch.signing_root(domain);
@@ -334,7 +337,7 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         }
 
         // Check for slashing conditions.
-        let fork = self.fork();
+        let fork = self.fork(block.epoch());
         let domain = self.spec.get_domain(
             block.epoch(),
             Domain::BeaconProposer,
@@ -403,7 +406,7 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         }
 
         // Checking for slashing conditions.
-        let fork = self.fork();
+        let fork = self.fork(attestation.data.target.epoch);
 
         let domain = self.spec.get_domain(
             attestation.data.target.epoch,
@@ -486,8 +489,7 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         aggregate: Attestation<E>,
         selection_proof: SelectionProof,
     ) -> Result<SignedAggregateAndProof<E>, Error> {
-        // Take the fork early to avoid lock interleaving.
-        let fork = self.fork();
+        let fork = self.fork(aggregate.data.target.epoch);
 
         let proof = self.with_validator_keypair(validator_pubkey, move |keypair| {
             SignedAggregateAndProof::from_aggregate(
@@ -513,9 +515,6 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         validator_pubkey: PublicKeyBytes,
         slot: Slot,
     ) -> Result<SelectionProof, Error> {
-        // Take the fork early to avoid lock interleaving.
-        let fork = self.fork();
-
         // Bypass the `with_validator_keypair` function.
         //
         // This is because we don't care about doppelganger protection when it comes to selection
@@ -531,7 +530,7 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         let proof = SelectionProof::new::<E>(
             slot,
             &keypair.sk,
-            &fork,
+            &self.fork(slot.epoch(E::slots_per_epoch())),
             self.genesis_validators_root,
             &self.spec,
         );
@@ -541,6 +540,93 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore<T, E> {
         Ok(proof)
     }
 
+    /// Produce a `SyncSelectionProof` for `slot` signed by the secret key of `validator_pubkey`.
+    pub fn produce_sync_selection_proof(
+        &self,
+        validator_pubkey: &PublicKeyBytes,
+        slot: Slot,
+        subnet_id: SyncSubnetId,
+    ) -> Result<SyncSelectionProof, Error> {
+        // Bypass `with_validator_keypair`: sync committee messages are not slashable.
+        let validators = self.validators.read();
+        let voting_keypair = validators
+            .voting_keypair(validator_pubkey)
+            .ok_or(Error::UnknownPubkey(*validator_pubkey))?;
+
+        metrics::inc_counter_vec(
+            &metrics::SIGNED_SYNC_SELECTION_PROOFS_TOTAL,
+            &[metrics::SUCCESS],
+        );
+
+        Ok(SyncSelectionProof::new::<E>(
+            slot,
+            subnet_id.into(),
+            &voting_keypair.sk,
+            &self.fork(slot.epoch(E::slots_per_epoch())),
+            self.genesis_validators_root,
+            &self.spec,
+        ))
+    }
+
+    pub fn produce_sync_committee_signature(
+        &self,
+        slot: Slot,
+        beacon_block_root: Hash256,
+        validator_index: u64,
+        validator_pubkey: &PublicKeyBytes,
+    ) -> Result<SyncCommitteeMessage, Error> {
+        // Bypass `with_validator_keypair`: sync committee messages are not slashable.
+        let validators = self.validators.read();
+        let voting_keypair = validators
+            .voting_keypair(validator_pubkey)
+            .ok_or(Error::UnknownPubkey(*validator_pubkey))?;
+
+        metrics::inc_counter_vec(
+            &metrics::SIGNED_SYNC_COMMITTEE_MESSAGES_TOTAL,
+            &[metrics::SUCCESS],
+        );
+
+        Ok(SyncCommitteeMessage::new::<E>(
+            slot,
+            beacon_block_root,
+            validator_index,
+            &voting_keypair.sk,
+            &self.fork(slot.epoch(E::slots_per_epoch())),
+            self.genesis_validators_root,
+            &self.spec,
+        ))
+    }
+
+    pub fn produce_signed_contribution_and_proof(
+        &self,
+        aggregator_index: u64,
+        aggregator_pubkey: &PublicKeyBytes,
+        contribution: SyncCommitteeContribution<E>,
+        selection_proof: SyncSelectionProof,
+    ) -> Result<SignedContributionAndProof<E>, Error> {
+        // Bypass `with_validator_keypair`: sync committee messages are not slashable.
+        let validators = self.validators.read();
+        let voting_keypair = validators
+            .voting_keypair(aggregator_pubkey)
+            .ok_or(Error::UnknownPubkey(*aggregator_pubkey))?;
+        let fork = self.fork(contribution.slot.epoch(E::slots_per_epoch()));
+
+        metrics::inc_counter_vec(
+            &metrics::SIGNED_SYNC_COMMITTEE_CONTRIBUTIONS_TOTAL,
+            &[metrics::SUCCESS],
+        );
+
+        Ok(SignedContributionAndProof::from_aggregate(
+            aggregator_index,
+            contribution,
+            Some(selection_proof),
+            &voting_keypair.sk,
+            &fork,
+            self.genesis_validators_root,
+            &self.spec,
+        ))
+    }
+
     /// Prune the slashing protection database so that it remains performant.
     ///
     /// This function will only do actual pruning periodically, so it should usually be