Use is_future_epoch in BLS to execution change gossip (#5600)

Author: jihoonsong

specs/capella/p2p-interface.md

@@ -220,11 +220,7 @@ def validate_bls_to_execution_change_gossip(
         raise GossipIgnore("already seen BLS to execution change for this validator")
 
     # [IGNORE] The current epoch is at or after the Capella fork epoch
-    # (where current_epoch is defined by the current wall-clock time)
-    time_since_genesis_ms = current_time_ms - store.genesis_time * 1000
-    current_slot = Slot(time_since_genesis_ms // SLOT_DURATION_MS)
-    current_epoch = compute_epoch_at_slot(current_slot)
-    if current_epoch < CAPELLA_FORK_EPOCH:
+    if is_future_epoch(store, CAPELLA_FORK_EPOCH, current_time_ms):
         raise GossipIgnore("current epoch is pre-capella")
 
     state = store.block_states[get_head(store).root]

tests/core/pyspec/eth_consensus_specs/test/capella/networking/test_gossip_bls_to_execution_change.py

@@ -112,6 +112,97 @@ def test_gossip_bls_to_execution_change__ignore_pre_capella(spec, state):
     )
 
 
+@with_phases([CAPELLA])
+@spec_configured_state_test({"CAPELLA_FORK_EPOCH": 1})
+def test_gossip_bls_to_execution_change__ignore_before_clock_disparity(spec, state):
+    """
+    Test that a `bls_to_execution_change` is ignored immediately before the
+    Capella fork epoch's clock-disparity window opens.
+    """
+    yield "topic", "meta", "bls_to_execution_change"
+    yield "state", state
+
+    store, signed_anchor = get_store_from_state(spec, state)
+    yield get_filename(signed_anchor), signed_anchor
+    yield "blocks", "meta", [{"block": get_filename(signed_anchor)}]
+
+    seen = get_seen(spec)
+    signed_bls_to_execution_change = get_signed_bls_to_execution_change(spec, state)
+    capella_fork_time_ms = get_capella_fork_time_ms(spec, store)
+    current_time_ms = capella_fork_time_ms - spec.config.MAXIMUM_GOSSIP_CLOCK_DISPARITY - 1
+
+    yield get_filename(signed_bls_to_execution_change), signed_bls_to_execution_change
+    yield "current_time_ms", "meta", int(current_time_ms)
+
+    result, reason = run_validate_gossip(
+        spec,
+        seen=seen,
+        store=store,
+        signed_bls_to_execution_change=signed_bls_to_execution_change,
+        current_time_ms=current_time_ms,
+    )
+    assert result == "ignore"
+    assert reason == "current epoch is pre-capella"
+
+    yield (
+        "messages",
+        "meta",
+        [
+            {
+                "offset_ms": 0,
+                "message": get_filename(signed_bls_to_execution_change),
+                "expected": "ignore",
+                "reason": reason,
+            }
+        ],
+    )
+
+
+@with_phases([CAPELLA])
+@spec_configured_state_test({"CAPELLA_FORK_EPOCH": 1})
+def test_gossip_bls_to_execution_change__valid_at_clock_disparity(spec, state):
+    """
+    Test that a `bls_to_execution_change` is valid when the Capella fork epoch's
+    clock-disparity window opens while the head state is still in the previous epoch.
+    """
+    yield "topic", "meta", "bls_to_execution_change"
+    yield "state", state
+
+    store, signed_anchor = get_store_from_state(spec, state)
+    yield get_filename(signed_anchor), signed_anchor
+    yield "blocks", "meta", [{"block": get_filename(signed_anchor)}]
+
+    seen = get_seen(spec)
+    signed_bls_to_execution_change = get_signed_bls_to_execution_change(spec, state)
+    capella_fork_time_ms = get_capella_fork_time_ms(spec, store)
+    current_time_ms = capella_fork_time_ms - spec.config.MAXIMUM_GOSSIP_CLOCK_DISPARITY
+
+    yield get_filename(signed_bls_to_execution_change), signed_bls_to_execution_change
+    yield "current_time_ms", "meta", int(current_time_ms)
+
+    result, reason = run_validate_gossip(
+        spec,
+        seen=seen,
+        store=store,
+        signed_bls_to_execution_change=signed_bls_to_execution_change,
+        current_time_ms=current_time_ms,
+    )
+    assert result == "valid"
+    assert reason is None
+
+    yield (
+        "messages",
+        "meta",
+        [
+            {
+                "offset_ms": 0,
+                "message": get_filename(signed_bls_to_execution_change),
+                "expected": "valid",
+            }
+        ],
+    )
+
+
 @with_capella_and_later
 @spec_configured_state_test({"CAPELLA_FORK_EPOCH": 0}, activate_at_genesis=True)
 def test_gossip_bls_to_execution_change__ignore_already_seen(spec, state):