From 3bf0aa99088d2a82e317042982c06affd39a8601 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Thu, 21 Nov 2019 11:15:47 +1100
Subject: [PATCH] Reject empty attestations

---
 beacon_node/beacon_chain/src/beacon_chain.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index 161eac2a25..c050077094 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -74,6 +74,7 @@ pub enum BlockProcessingOutcome {
 #[derive(Debug, PartialEq)]
 pub enum AttestationProcessingOutcome {
     Processed,
+    EmptyAggregationBitfield,
     UnknownHeadBlock {
         beacon_block_root: Hash256,
     },
@@ -692,6 +693,10 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         metrics::inc_counter(&metrics::ATTESTATION_PROCESSING_REQUESTS);
         let timer = metrics::start_timer(&metrics::ATTESTATION_PROCESSING_TIMES);
 
+        if attestation.aggregation_bits.num_set_bits() == 0 {
+            return Ok(AttestationProcessingOutcome::EmptyAggregationBitfield);
+        }
+
         // From the store, load the attestation's "head block".
         //
         // An honest validator would have set this block to be the head of the chain (i.e., the