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/lib.rs

@@ -2,6 +2,7 @@
 #[macro_use]
 extern crate lazy_static;
 
+pub mod attestation_verification;
 mod beacon_chain;
 mod beacon_snapshot;
 mod block_verification;
@@ -14,6 +15,9 @@ mod head_tracker;
 mod metrics;
 pub mod migrate;
 mod naive_aggregation_pool;
+mod observed_attestations;
+mod observed_attesters;
+mod observed_block_producers;
 mod persisted_beacon_chain;
 mod shuffling_cache;
 mod snapshot_cache;
@@ -22,11 +26,12 @@ mod timeout_rw_lock;
 mod validator_pubkey_cache;
 
 pub use self::beacon_chain::{
-    AttestationProcessingOutcome, AttestationType, BeaconChain, BeaconChainTypes,
-    ChainSegmentResult, StateSkipConfig,
+    AttestationProcessingOutcome, BeaconChain, BeaconChainTypes, ChainSegmentResult,
+    StateSkipConfig,
 };
 pub use self::beacon_snapshot::BeaconSnapshot;
 pub use self::errors::{BeaconChainError, BlockProductionError};
+pub use attestation_verification::Error as AttestationError;
 pub use block_verification::{BlockError, BlockProcessingOutcome, GossipVerifiedBlock};
 pub use eth1_chain::{Eth1Chain, Eth1ChainBackend};
 pub use events::EventHandler;