Add attestation gossip pre-verification (#983)

* Add PH & MS slot clock changes

* Account for genesis time

* Add progress on duties refactor

* Add simple is_aggregator bool to val subscription

* Start work on attestation_verification.rs

* Add progress on ObservedAttestations

* Progress with ObservedAttestations

* Fix tests

* Add observed attestations to the beacon chain

* Add attestation observation to processing code

* Add progress on attestation verification

* Add first draft of ObservedAttesters

* Add more tests

* Add observed attesters to beacon chain

* Add observers to attestation processing

* Add more attestation verification

* Create ObservedAggregators map

* Remove commented-out code

* Add observed aggregators into chain

* Add progress

* Finish adding features to attestation verification

* Ensure beacon chain compiles

* Link attn verification into chain

* Integrate new attn verification in chain

* Remove old attestation processing code

* Start trying to fix beacon_chain tests

* Split adding into pools into two functions

* Add aggregation to harness

* Get test harness working again

* Adjust the number of aggregators for test harness

* Fix edge-case in harness

* Integrate new attn processing in network

* Fix compile bug in validator_client

* Update validator API endpoints

* Fix aggreagation in test harness

* Fix enum thing

* Fix attestation observation bug:

* Patch failing API tests

* Start adding comments to attestation verification

* Remove unused attestation field

* Unify "is block known" logic

* Update comments

* Supress fork choice errors for network processing

* Add todos

* Tidy

* Add gossip attn tests

* Disallow test harness to produce old attns

* Comment out in-progress tests

* Partially address pruning tests

* Fix failing store test

* Add aggregate tests

* Add comments about which spec conditions we check

* Dont re-aggregate

* Split apart test harness attn production

* Fix compile error in network

* Make progress on commented-out test

* Fix skipping attestation test

* Add fork choice verification tests

* Tidy attn tests, remove dead code

* Remove some accidentally added code

* Fix clippy lint

* Rename test file

* Add block tests, add cheap block proposer check

* Rename block testing file

* Add observed_block_producers

* Tidy

* Switch around block signature verification

* Finish block testing

* Remove gossip from signature tests

* First pass of self review

* Fix deviation in spec

* Update test spec tags

* Start moving over to hashset

* Finish moving observed attesters to hashmap

* Move aggregation pool over to hashmap

* Make fc attn borrow again

* Fix rest_api compile error

* Fix missing comments

* Fix monster test

* Uncomment increasing slots test

* Address remaining comments

* Remove unsafe, use cfg test

* Remove cfg test flag

* Fix dodgy comment

* Ignore aggregates that are already known.

* Unify aggregator modulo logic

* Fix typo in logs

* Refactor validator subscription logic

* Avoid reproducing selection proof

* Skip HTTP call if no subscriptions

* Rename DutyAndState -> DutyAndProof

* Tidy logs

* Print root as dbg

* Fix compile errors in tests

* Fix compile error in test

eth2/state_processing/src/per_block_processing/block_signature_verifier.rs

@@ -22,6 +22,10 @@ pub enum Error {
     /// There was an error attempting to read from a `BeaconState`. Block
     /// validity was not determined.
     BeaconStateError(BeaconStateError),
+    /// The `BeaconBlock` has a `proposer_index` that does not match the index we computed locally.
+    ///
+    /// The block is invalid.
+    IncorrectBlockProposer { block: u64, local_shuffling: u64 },
     /// Failed to load a signature set. The block may be invalid or we failed to process it.
     SignatureSetError(SignatureSetError),
 }
@@ -34,7 +38,18 @@ impl From<BeaconStateError> for Error {
 
 impl From<SignatureSetError> for Error {
     fn from(e: SignatureSetError) -> Error {
-        Error::SignatureSetError(e)
+        match e {
+            // Make a special distinction for `IncorrectBlockProposer` since it indicates an
+            // invalid block, not an internal error.
+            SignatureSetError::IncorrectBlockProposer {
+                block,
+                local_shuffling,
+            } => Error::IncorrectBlockProposer {
+                block,
+                local_shuffling,
+            },
+            e => Error::SignatureSetError(e),
+        }
     }
 }
 

eth2/state_processing/src/per_block_processing/signature_sets.rs

@@ -10,8 +10,8 @@ use tree_hash::TreeHash;
 use types::{
     AggregateSignature, AttesterSlashing, BeaconBlock, BeaconState, BeaconStateError, ChainSpec,
     DepositData, Domain, EthSpec, Fork, Hash256, IndexedAttestation, ProposerSlashing, PublicKey,
-    Signature, SignedBeaconBlock, SignedBeaconBlockHeader, SignedRoot, SignedVoluntaryExit,
-    SigningRoot,
+    Signature, SignedAggregateAndProof, SignedBeaconBlock, SignedBeaconBlockHeader, SignedRoot,
+    SignedVoluntaryExit, SigningRoot,
 };
 
 pub type Result<T> = std::result::Result<T, Error>;
@@ -26,6 +26,10 @@ pub enum Error {
     /// Attempted to find the public key of a validator that does not exist. You cannot distinguish
     /// between an error and an invalid block in this case.
     ValidatorUnknown(u64),
+    /// The `BeaconBlock` has a `proposer_index` that does not match the index we computed locally.
+    ///
+    /// The block is invalid.
+    IncorrectBlockProposer { block: u64, local_shuffling: u64 },
     /// The public keys supplied do not match the number of objects requiring keys. Block validity
     /// was not determined.
     MismatchedPublicKeyLen { pubkey_len: usize, other_len: usize },
@@ -73,6 +77,13 @@ where
     let block = &signed_block.message;
     let proposer_index = state.get_beacon_proposer_index(block.slot, spec)?;
 
+    if proposer_index as u64 != block.proposer_index {
+        return Err(Error::IncorrectBlockProposer {
+            block: block.proposer_index,
+            local_shuffling: proposer_index as u64,
+        });
+    }
+
     let domain = spec.get_domain(
         block.slot.epoch(T::slots_per_epoch()),
         Domain::BeaconProposer,
@@ -343,3 +354,74 @@ where
         message,
     ))
 }
+
+pub fn signed_aggregate_selection_proof_signature_set<'a, T, F>(
+    get_pubkey: F,
+    signed_aggregate_and_proof: &'a SignedAggregateAndProof<T>,
+    fork: &Fork,
+    genesis_validators_root: Hash256,
+    spec: &'a ChainSpec,
+) -> Result<SignatureSet>
+where
+    T: EthSpec,
+    F: Fn(usize) -> Option<Cow<'a, PublicKey>>,
+{
+    let slot = signed_aggregate_and_proof.message.aggregate.data.slot;
+
+    let domain = spec.get_domain(
+        slot.epoch(T::slots_per_epoch()),
+        Domain::SelectionProof,
+        fork,
+        genesis_validators_root,
+    );
+    let message = slot.signing_root(domain).as_bytes().to_vec();
+    let signature = &signed_aggregate_and_proof.message.selection_proof;
+    let validator_index = signed_aggregate_and_proof.message.aggregator_index;
+
+    Ok(SignatureSet::single(
+        signature,
+        get_pubkey(validator_index as usize)
+            .ok_or_else(|| Error::ValidatorUnknown(validator_index))?,
+        message,
+    ))
+}
+
+pub fn signed_aggregate_signature_set<'a, T, F>(
+    get_pubkey: F,
+    signed_aggregate_and_proof: &'a SignedAggregateAndProof<T>,
+    fork: &Fork,
+    genesis_validators_root: Hash256,
+    spec: &'a ChainSpec,
+) -> Result<SignatureSet>
+where
+    T: EthSpec,
+    F: Fn(usize) -> Option<Cow<'a, PublicKey>>,
+{
+    let target_epoch = signed_aggregate_and_proof
+        .message
+        .aggregate
+        .data
+        .target
+        .epoch;
+
+    let domain = spec.get_domain(
+        target_epoch,
+        Domain::AggregateAndProof,
+        fork,
+        genesis_validators_root,
+    );
+    let message = signed_aggregate_and_proof
+        .message
+        .signing_root(domain)
+        .as_bytes()
+        .to_vec();
+    let signature = &signed_aggregate_and_proof.signature;
+    let validator_index = signed_aggregate_and_proof.message.aggregator_index;
+
+    Ok(SignatureSet::single(
+        signature,
+        get_pubkey(validator_index as usize)
+            .ok_or_else(|| Error::ValidatorUnknown(validator_index))?,
+        message,
+    ))
+}

eth2/state_processing/src/per_block_processing/tests.rs

@@ -1039,7 +1039,12 @@ fn invalid_proposer_slashing_duplicate_slashing() {
 
     let slashing = block.message.body.proposer_slashings[0].clone();
     let slashed_proposer = slashing.signed_header_1.message.proposer_index;
-    block.message.body.proposer_slashings.push(slashing);
+    block
+        .message
+        .body
+        .proposer_slashings
+        .push(slashing)
+        .expect("should push slashing");
 
     let result = per_block_processing(
         &mut state,