Attestation processing (#497)

* Renamed fork_choice::process_attestation_from_block

* Processing attestation in fork choice

* Retrieving state from store and checking signature

* Looser check on beacon state validity.

* Cleaned up get_attestation_state

* Expanded fork choice api to provide latest validator message.

* Checking if the an attestation contains a latest message

* Correct process_attestation error handling.

* Copy paste error in comment fixed.

* Tidy ancestor iterators

* Getting attestation slot via helper method

* Refactored attestation creation in test utils

* Revert "Refactored attestation creation in test utils"

This reverts commit 4d277fe4239a7194758b18fb5c00dfe0b8231306.

* Integration tests for free attestation processing

* Implicit conflicts resolved.

* formatting

* Do first pass on Grants code

* Add another attestation processing test

* Tidy attestation processing

* Remove old code fragment

* Add non-compiling half finished changes

* Simplify, fix bugs, add tests for chain iters

* Remove attestation processing from op pool

* Fix bug with fork choice, tidy

* Fix overly restrictive check in fork choice.

* Ensure committee cache is build during attn proc

* Ignore unknown blocks at fork choice

* Various minor fixes

* Make fork choice write lock in to read lock

* Remove unused method

* Tidy comments

* Fix attestation prod. target roots change

* Fix compile error in store iters

* Reject any attestation prior to finalization

* Fix minor PR comments

* Remove duplicated attestation finalization check

* Remove awkward `let` statement

beacon_node/network/src/sync/simple_sync.rs

@@ -266,8 +266,7 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
 
     fn root_at_slot(&self, target_slot: Slot) -> Option<Hash256> {
         self.chain
-            .rev_iter_block_roots(target_slot)
-            .take(1)
+            .rev_iter_block_roots()
             .find(|(_root, slot)| *slot == target_slot)
             .map(|(root, _slot)| root)
     }
@@ -280,8 +279,6 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
         req: BeaconBlockRootsRequest,
         network: &mut NetworkContext,
     ) {
-        let state = &self.chain.head().beacon_state;
-
         debug!(
             self.log,
             "BlockRootsRequest";
@@ -292,8 +289,9 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
 
         let mut roots: Vec<BlockRootSlot> = self
             .chain
-            .rev_iter_block_roots(std::cmp::min(req.start_slot + req.count, state.slot))
+            .rev_iter_block_roots()
             .take_while(|(_root, slot)| req.start_slot <= *slot)
+            .filter(|(_root, slot)| *slot < req.start_slot + req.count)
             .map(|(block_root, slot)| BlockRootSlot { slot, block_root })
             .collect();
 
@@ -391,8 +389,6 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
         req: BeaconBlockHeadersRequest,
         network: &mut NetworkContext,
     ) {
-        let state = &self.chain.head().beacon_state;
-
         debug!(
             self.log,
             "BlockHeadersRequest";
@@ -405,8 +401,9 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
         // Collect the block roots.
         let mut roots: Vec<Hash256> = self
             .chain
-            .rev_iter_block_roots(std::cmp::min(req.start_slot + count, state.slot))
+            .rev_iter_block_roots()
             .take_while(|(_root, slot)| req.start_slot <= *slot)
+            .filter(|(_root, slot)| *slot < req.start_slot + count)
             .map(|(root, _slot)| root)
             .collect();
 
@@ -631,7 +628,12 @@ impl<T: BeaconChainTypes> SimpleSync<T> {
         _network: &mut NetworkContext,
     ) {
         match self.chain.process_attestation(msg) {
-            Ok(()) => info!(self.log, "ImportedAttestation"; "source" => "gossip"),
+            Ok(outcome) => info!(
+                self.log,
+                "Processed attestation";
+                "source" => "gossip",
+                "outcome" => format!("{:?}", outcome)
+            ),
             Err(e) => {
                 warn!(self.log, "InvalidAttestation"; "source" => "gossip", "error" => format!("{:?}", e))
             }