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/rpc/src/attestation.rs

@@ -1,4 +1,4 @@
-use beacon_chain::{BeaconChain, BeaconChainTypes};
+use beacon_chain::{BeaconChain, BeaconChainError, BeaconChainTypes};
 use eth2_libp2p::PubsubMessage;
 use eth2_libp2p::Topic;
 use eth2_libp2p::BEACON_ATTESTATION_TOPIC;
@@ -163,7 +163,7 @@ impl<T: BeaconChainTypes> AttestationService for AttestationServiceInstance<T> {
 
                 resp.set_success(true);
             }
-            Err(e) => {
+            Err(BeaconChainError::AttestationValidationError(e)) => {
                 // Attestation was invalid
                 warn!(
                     self.log,
@@ -174,6 +174,36 @@ impl<T: BeaconChainTypes> AttestationService for AttestationServiceInstance<T> {
                 resp.set_success(false);
                 resp.set_msg(format!("InvalidAttestation: {:?}", e).as_bytes().to_vec());
             }
+            Err(BeaconChainError::IndexedAttestationValidationError(e)) => {
+                // Indexed attestation was invalid
+                warn!(
+                    self.log,
+                    "PublishAttestation";
+                    "type" => "invalid_attestation",
+                    "error" => format!("{:?}", e),
+                );
+                resp.set_success(false);
+                resp.set_msg(
+                    format!("InvalidIndexedAttestation: {:?}", e)
+                        .as_bytes()
+                        .to_vec(),
+                );
+            }
+            Err(e) => {
+                // Some other error
+                warn!(
+                    self.log,
+                    "PublishAttestation";
+                    "type" => "beacon_chain_error",
+                    "error" => format!("{:?}", e),
+                );
+                resp.set_success(false);
+                resp.set_msg(
+                    format!("There was a beacon chain error: {:?}", e)
+                        .as_bytes()
+                        .to_vec(),
+                );
+            }
         };
 
         let error_log = self.log.clone();