Ensure merge transition block contains 🐼

specs/bellatrix/fork-choice.md

@@ -130,6 +130,8 @@ def validate_merge_block(block: BeaconBlock) -> None:
     and a client software MAY delay a call to ``validate_merge_block``
     until the PoW block(s) become available.
     """
+    assert '🐼'.encode('utf8') in block.body.graffiti
+
     if TERMINAL_BLOCK_HASH != Hash32():
         # If `TERMINAL_BLOCK_HASH` is used as an override, the activation epoch must be reached.
         assert compute_epoch_at_slot(block.slot) >= TERMINAL_BLOCK_HASH_ACTIVATION_EPOCH

specs/bellatrix/validator.md

@@ -110,9 +110,10 @@ All validator responsibilities remain unchanged other than those noted below. Na
 
 To obtain an execution payload, a block proposer building a block on top of a `state` must take the following actions:
 
-1. Set `payload_id = prepare_execution_payload(state, pow_chain, safe_block_hash, finalized_block_hash, suggested_fee_recipient, execution_engine)`, where:
+1. Set `payload_id = prepare_execution_payload(state, pow_chain, graffiti, safe_block_hash, finalized_block_hash, suggested_fee_recipient, execution_engine)`, where:
     * `state` is the state object after applying `process_slots(state, slot)` transition to the resulting state of the parent block processing
     * `pow_chain` is a `Dict[Hash32, PowBlock]` dictionary that abstractly represents all blocks in the PoW chain with block hash as the dictionary key
+    * `graffiti` is the configured value to use as the beacon block's graffiti
     * `safe_block_hash` is the return value of the `get_safe_execution_payload_hash(store: Store)` function call
     * `finalized_block_hash` is the hash of the latest finalized execution payload (`Hash32()` if none yet finalized)
     * `suggested_fee_recipient` is the value suggested to be used for the `fee_recipient` field of the execution payload
@@ -121,11 +122,16 @@ To obtain an execution payload, a block proposer building a block on top of a `s
 ```python
 def prepare_execution_payload(state: BeaconState,
                               pow_chain: Dict[Hash32, PowBlock],
+                              graffiti: Bytes32,
                               safe_block_hash: Hash32,
                               finalized_block_hash: Hash32,
                               suggested_fee_recipient: ExecutionAddress,
                               execution_engine: ExecutionEngine) -> Optional[PayloadId]:
     if not is_merge_transition_complete(state):
+        if '🐼'.encode('utf8') not in graffiti:
+            # Incompatible graffiti for merge transition block
+            return None
+
         is_terminal_block_hash_set = TERMINAL_BLOCK_HASH != Hash32()
         is_activation_epoch_reached = get_current_epoch(state) >= TERMINAL_BLOCK_HASH_ACTIVATION_EPOCH
         if is_terminal_block_hash_set and not is_activation_epoch_reached:

specs/capella/validator.md

@@ -71,11 +71,16 @@ def get_expected_withdrawals(state: BeaconState) -> Sequence[Withdrawal]:
 ```python
 def prepare_execution_payload(state: BeaconState,
                               pow_chain: Dict[Hash32, PowBlock],
+                              graffiti: Bytes32,
                               safe_block_hash: Hash32,
                               finalized_block_hash: Hash32,
                               suggested_fee_recipient: ExecutionAddress,
                               execution_engine: ExecutionEngine) -> Optional[PayloadId]:
     if not is_merge_transition_complete(state):
+        if '🐼'.encode('utf8') not in graffiti:
+            # Incompatible graffiti for merge transition block
+            return None
+
         is_terminal_block_hash_set = TERMINAL_BLOCK_HASH != Hash32()
         is_activation_epoch_reached = get_current_epoch(state) >= TERMINAL_BLOCK_HASH_ACTIVATION_EPOCH
         if is_terminal_block_hash_set and not is_activation_epoch_reached:

tests/core/pyspec/eth2spec/test/bellatrix/unittests/test_validate_merge_block.py

@@ -91,6 +91,30 @@ def test_validate_merge_block_fail_after_terminal(spec, state):
     run_validate_merge_block(spec, pow_chain, block, valid=False)
 
 
+@with_bellatrix_and_later
+@spec_state_test
+def test_validate_merge_block_success_inline_panda(spec, state):
+    pow_chain = prepare_random_pow_chain(spec, 2)
+    pow_chain.head(-1).total_difficulty = spec.config.TERMINAL_TOTAL_DIFFICULTY - uint256(1)
+    pow_chain.head().total_difficulty = spec.config.TERMINAL_TOTAL_DIFFICULTY
+    block = build_empty_block_for_next_slot(spec, state)
+    block.body.graffiti = b'\x00' * 8 + '🐼'.encode('utf8') + b'\x00' * 20
+    block.body.execution_payload.parent_hash = pow_chain.head().block_hash
+    run_validate_merge_block(spec, pow_chain, block)
+
+
+@with_bellatrix_and_later
+@spec_state_test
+def test_validate_merge_block_fail_no_panda(spec, state):
+    pow_chain = prepare_random_pow_chain(spec, 2)
+    pow_chain.head(-1).total_difficulty = spec.config.TERMINAL_TOTAL_DIFFICULTY - uint256(1)
+    pow_chain.head().total_difficulty = spec.config.TERMINAL_TOTAL_DIFFICULTY
+    block = build_empty_block_for_next_slot(spec, state)
+    block.body.graffiti = b'\x00' * 32
+    block.body.execution_payload.parent_hash = pow_chain.head().block_hash
+    run_validate_merge_block(spec, pow_chain, block, valid=False)
+
+
 @with_bellatrix_and_later
 @spec_configured_state_test({
     'TERMINAL_BLOCK_HASH': TERMINAL_BLOCK_HASH_CONFIG_VAR,

tests/core/pyspec/eth2spec/test/bellatrix/unittests/validator/test_validator.py

@@ -69,24 +69,40 @@ def test_get_pow_block_at_terminal_total_difficulty(spec, state):
 
 SAMPLE_PAYLOAD_ID = b'\x12' * 8
 # ('is_merge_complete', 'is_terminal_block_hash_set', 'is_activation_epoch_reached',
-# 'terminal_pow_block_is_none', 'result_payload_id')
+# 'terminal_pow_block_is_none', 'is_graffiti_compatible', 'result_payload_id')
 prepare_execution_payload_expected_results = [
-    (False, False, False, False, SAMPLE_PAYLOAD_ID),
-    (False, False, False, True, None),
-    (False, False, True, False, SAMPLE_PAYLOAD_ID),
-    (False, False, True, True, None),
-    (False, True, False, False, None),
-    (False, True, False, True, None),
-    (False, True, True, False, SAMPLE_PAYLOAD_ID),
-    (False, True, True, True, None),
-    (True, False, False, False, SAMPLE_PAYLOAD_ID),
-    (True, False, False, True, SAMPLE_PAYLOAD_ID),
-    (True, False, True, False, SAMPLE_PAYLOAD_ID),
-    (True, False, True, True, SAMPLE_PAYLOAD_ID),
-    (True, True, False, False, SAMPLE_PAYLOAD_ID),
-    (True, True, False, True, SAMPLE_PAYLOAD_ID),
-    (True, True, True, False, SAMPLE_PAYLOAD_ID),
-    (True, True, True, True, SAMPLE_PAYLOAD_ID),
+    (False, False, False, False, True, SAMPLE_PAYLOAD_ID),
+    (False, False, False, True, True, None),
+    (False, False, True, False, True, SAMPLE_PAYLOAD_ID),
+    (False, False, True, True, True, None),
+    (False, True, False, False, True, None),
+    (False, True, False, True, True, None),
+    (False, True, True, False, True, SAMPLE_PAYLOAD_ID),
+    (False, True, True, True, True, None),
+    (True, False, False, False, True, SAMPLE_PAYLOAD_ID),
+    (True, False, False, True, True, SAMPLE_PAYLOAD_ID),
+    (True, False, True, False, True, SAMPLE_PAYLOAD_ID),
+    (True, False, True, True, True, SAMPLE_PAYLOAD_ID),
+    (True, True, False, False, True, SAMPLE_PAYLOAD_ID),
+    (True, True, False, True, True, SAMPLE_PAYLOAD_ID),
+    (True, True, True, False, True, SAMPLE_PAYLOAD_ID),
+    (True, True, True, True, True, SAMPLE_PAYLOAD_ID),
+    (False, False, False, False, False, None),
+    (False, False, False, True, False, None),
+    (False, False, True, False, False, None),
+    (False, False, True, True, False, None),
+    (False, True, False, False, False, None),
+    (False, True, False, True, False, None),
+    (False, True, True, False, False, None),
+    (False, True, True, True, False, None),
+    (True, False, False, False, False, SAMPLE_PAYLOAD_ID),
+    (True, False, False, True, False, SAMPLE_PAYLOAD_ID),
+    (True, False, True, False, False, SAMPLE_PAYLOAD_ID),
+    (True, False, True, True, False, SAMPLE_PAYLOAD_ID),
+    (True, True, False, False, False, SAMPLE_PAYLOAD_ID),
+    (True, True, False, True, False, SAMPLE_PAYLOAD_ID),
+    (True, True, True, False, False, SAMPLE_PAYLOAD_ID),
+    (True, True, True, True, False, SAMPLE_PAYLOAD_ID),
 ]
 
 
@@ -99,6 +115,7 @@ def test_prepare_execution_payload(spec, state):
             is_terminal_block_hash_set,
             is_activation_epoch_reached,
             terminal_pow_block_is_none,
+            is_graffiti_compatible,
             result_payload_id,
         ) = result
 
@@ -141,6 +158,12 @@ def test_prepare_execution_payload(spec, state):
                 pow_chain.head().block_hash = _mock_terminal_block_hash
             pow_chain.head().total_difficulty = spec.config.TERMINAL_TOTAL_DIFFICULTY
 
+        # 4. Handle `is_graffiti_compatible`
+        if is_graffiti_compatible:
+            graffiti = '🐼'.encode('utf8') * 8
+        else:
+            graffiti = b'\x00' * 32
+
         # Dummy arguments
         finalized_block_hash = b'\x56' * 32
         safe_block_hash = b'\x58' * 32
@@ -158,6 +181,7 @@ def notify_forkchoice_updated(self,
         payload_id = spec.prepare_execution_payload(
             state=state,
             pow_chain=pow_chain.to_dict(),
+            graffiti=graffiti,
             safe_block_hash=safe_block_hash,
             finalized_block_hash=finalized_block_hash,
             suggested_fee_recipient=suggested_fee_recipient,

tests/core/pyspec/eth2spec/test/helpers/block.py

@@ -92,6 +92,7 @@ def build_empty_block(spec, state, slot=None):
     empty_block.proposer_index = spec.get_beacon_proposer_index(state)
     empty_block.body.eth1_data.deposit_count = state.eth1_deposit_index
     empty_block.parent_root = parent_block_root
+    empty_block.body.graffiti = '🐼'.encode('utf8') + b'\x00' * 28
 
     apply_randao_reveal(spec, state, empty_block)