From 36e48fba99be3db6fb64a25497a226f8bebab819 Mon Sep 17 00:00:00 2001
From: Danny Ryan <dannyjryan@gmail.com>
Date: Wed, 11 Mar 2020 12:46:47 -0600
Subject: [PATCH] enforce must match target to match head to avoid perverse
 incentive path

---
 setup.py                                      | 12 +++++++++-
 specs/phase0/beacon-chain.md                  |  2 +-
 .../test_process_rewards_and_penalties.py     | 23 +++++++++++++++++++
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/setup.py b/setup.py
index 6dd4de861..084f72901 100644
--- a/setup.py
+++ b/setup.py
@@ -182,7 +182,17 @@ get_active_validator_indices = cache_this(
 _get_beacon_committee = get_beacon_committee
 get_beacon_committee = cache_this(
     lambda state, slot, index: (state.validators.hash_tree_root(), state.randao_mixes.hash_tree_root(), slot, index),
-    _get_beacon_committee)'''
+    _get_beacon_committee)
+
+_get_matching_target_attestations = get_matching_target_attestations
+get_matching_target_attestations = cache_this(
+    lambda state, epoch: (state.hash_tree_root(), epoch),
+    _get_matching_target_attestations)
+
+_get_matching_head_attestations = get_matching_head_attestations
+get_matching_head_attestations = cache_this(
+    lambda state, epoch: (state.hash_tree_root(), epoch),
+    _get_matching_head_attestations)'''
 
 
 def objects_to_spec(spec_object: SpecObject, imports: str, fork: str) -> str:
diff --git a/specs/phase0/beacon-chain.md b/specs/phase0/beacon-chain.md
index 91cb9f714..ff80360c6 100644
--- a/specs/phase0/beacon-chain.md
+++ b/specs/phase0/beacon-chain.md
@@ -1235,7 +1235,7 @@ def get_matching_target_attestations(state: BeaconState, epoch: Epoch) -> Sequen
 ```python
 def get_matching_head_attestations(state: BeaconState, epoch: Epoch) -> Sequence[PendingAttestation]:
     return [
-        a for a in get_matching_source_attestations(state, epoch)
+        a for a in get_matching_target_attestations(state, epoch)
         if a.data.beacon_block_root == get_block_root_at_slot(state, a.data.slot)
     ]
 ```
diff --git a/tests/core/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_rewards_and_penalties.py b/tests/core/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_rewards_and_penalties.py
index b4f50179e..111033799 100644
--- a/tests/core/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_rewards_and_penalties.py
+++ b/tests/core/pyspec/eth2spec/test/phase_0/epoch_processing/test_process_rewards_and_penalties.py
@@ -97,6 +97,29 @@ def test_full_attestations(spec, state):
             assert state.balances[index] < pre_state.balances[index]
 
 
+@with_all_phases
+@spec_state_test
+def test_full_attestations_random_incorrect_fields(spec, state):
+    attestations = prepare_state_with_full_attestations(spec, state)
+    for i, attestation in enumerate(state.previous_epoch_attestations):
+        if i % 3 == 0:
+            # Mess up some head votes
+            attestation.data.beacon_block_root = b'\x56' * 32
+        if i % 3 == 1:
+            # Message up some target votes
+            attestation.data.target.root = b'\x23' * 32
+        if i % 3 == 2:
+            # Keep some votes 100% correct
+            pass
+
+    yield from run_process_rewards_and_penalties(spec, state)
+
+    attesting_indices = spec.get_unslashed_attesting_indices(state, attestations)
+    assert len(attesting_indices) > 0
+    # No balance checks, non-trivial base on group rewards
+    # Mainly for consensus tests
+
+
 @with_all_phases
 @spec_test
 @with_custom_state(balances_fn=misc_balances, threshold_fn=default_activation_threshold)