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

beacon_node/beacon_chain/src/block_verification/block_processing_outcome.rs

@@ -14,6 +14,8 @@ pub enum BlockProcessingOutcome {
     InvalidSignature,
     /// The proposal signature in invalid.
     ProposalSignatureInvalid,
+    /// The `block.proposal_index` is not known.
+    UnknownValidator(u64),
     /// The parent block was unknown.
     ParentUnknown(Hash256),
     /// The block slot is greater than the present slot.
@@ -35,6 +37,11 @@ pub enum BlockProcessingOutcome {
     },
     /// Block is already known, no need to re-import.
     BlockIsAlreadyKnown,
+    /// A block for this proposer and slot has already been observed.
+    RepeatProposal {
+        proposer: u64,
+        slot: Slot,
+    },
     /// The block slot exceeds the MAXIMUM_BLOCK_SLOT_NUMBER.
     BlockSlotLimitReached,
     /// The provided block is from an earlier slot than its parent.
@@ -42,6 +49,13 @@ pub enum BlockProcessingOutcome {
         block_slot: Slot,
         state_slot: Slot,
     },
+    /// 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,
+    },
     /// At least one block in the chain segement did not have it's parent root set to the root of
     /// the prior block.
     NonLinearParentRoots,
@@ -78,12 +92,16 @@ impl BlockProcessingOutcome {
                 finalized_slot,
             }),
             Err(BlockError::BlockIsAlreadyKnown) => Ok(BlockProcessingOutcome::BlockIsAlreadyKnown),
+            Err(BlockError::RepeatProposal { proposer, slot }) => {
+                Ok(BlockProcessingOutcome::RepeatProposal { proposer, slot })
+            }
             Err(BlockError::BlockSlotLimitReached) => {
                 Ok(BlockProcessingOutcome::BlockSlotLimitReached)
             }
             Err(BlockError::ProposalSignatureInvalid) => {
                 Ok(BlockProcessingOutcome::ProposalSignatureInvalid)
             }
+            Err(BlockError::UnknownValidator(i)) => Ok(BlockProcessingOutcome::UnknownValidator(i)),
             Err(BlockError::InvalidSignature) => Ok(BlockProcessingOutcome::InvalidSignature),
             Err(BlockError::BlockIsNotLaterThanParent {
                 block_slot,
@@ -92,6 +110,13 @@ impl BlockProcessingOutcome {
                 block_slot,
                 state_slot,
             }),
+            Err(BlockError::IncorrectBlockProposer {
+                block,
+                local_shuffling,
+            }) => Ok(BlockProcessingOutcome::IncorrectBlockProposer {
+                block,
+                local_shuffling,
+            }),
             Err(BlockError::NonLinearParentRoots) => {
                 Ok(BlockProcessingOutcome::NonLinearParentRoots)
             }