Load gossip validation state from the store (#5563)

@nflaig and I have been chatting about how the `state` being passed into
gossip validation functions can be a bit ambiguous. This PR removes
`state` as a parameter to the `validate_*_gossip` functions. It then
gets the appropriate state from the forkchoice `Store`. I moved some
other checks around because we need to ensure the head state is valid
before getting it, otherwise it simply won't exist in `Store`.

Author: jtraglia

specs/altair/p2p-interface.md

@@ -224,13 +224,12 @@ Altair for further details.
 ##### New `sync_committee_contribution_and_proof`
 
 This topic is used to propagate partially aggregated sync committee messages to
-be included in future blocks. The `state` parameter is the head state.
+be included in future blocks.
 
 ```python
 def validate_sync_committee_contribution_and_proof_gossip(
     seen: Seen,
     store: Store,
-    state: BeaconState,
     signed_contribution_and_proof: SignedContributionAndProof,
     current_time_ms: Uint64,
 ) -> None:
@@ -257,6 +256,8 @@ def validate_sync_committee_contribution_and_proof_gossip(
     if not is_sync_committee_aggregator(contribution_and_proof.selection_proof):
         raise GossipReject("validator is not selected as aggregator")
 
+    state = store.block_states[get_head(store).root]
+
     # [REJECT] The aggregator index is valid
     if contribution_and_proof.aggregator_index >= len(state.validators):
         raise GossipReject("aggregator index out of range")
@@ -341,14 +342,12 @@ messages to subsections of the network.
 
 The `sync_committee_{subnet_id}` topics are used to propagate unaggregated sync
 committee messages to the subnet `subnet_id` to be aggregated before being
-gossiped to the global `sync_committee_contribution_and_proof` topic. The
-`state` parameter is the head state.
+gossiped to the global `sync_committee_contribution_and_proof` topic.
 
 ```python
 def validate_sync_committee_message_gossip(
     seen: Seen,
     store: Store,
-    state: BeaconState,
     sync_committee_message: SyncCommitteeMessage,
     current_time_ms: Uint64,
     subnet_id: SubnetID,
@@ -361,6 +360,8 @@ def validate_sync_committee_message_gossip(
     if not is_current_slot(store, sync_committee_message.slot, current_time_ms):
         raise GossipIgnore("message is not for the current slot")
 
+    state = store.block_states[get_head(store).root]
+
     # [REJECT] The validator index is valid
     if sync_committee_message.validator_index >= len(state.validators):
         raise GossipReject("validator index out of range")

specs/bellatrix/p2p-interface.md

@@ -105,8 +105,7 @@ Bellatrix changes the type of the global beacon block topic.
 ##### Modified `beacon_block`
 
 The `beacon_block` topic is used solely for propagating new signed beacon blocks
-to all nodes on the networks. Signed blocks are sent in their entirety. The
-`state` parameter is the head state.
+to all nodes on the networks. Signed blocks are sent in their entirety.
 
 *Note*: Blocks with execution enabled will be permitted to propagate regardless
 of the validity of the execution payload. This prevents network segregation
@@ -116,7 +115,6 @@ between [optimistic](./optimistic-sync.md) and non-optimistic nodes.
 def validate_beacon_block_gossip(
     seen: Seen,
     store: Store,
-    state: BeaconState,
     signed_beacon_block: SignedBeaconBlock,
     current_time_ms: Uint64,
     # [New in Bellatrix]
@@ -146,6 +144,34 @@ def validate_beacon_block_gossip(
     if proposer_slot_key in seen.proposer_slots:
         raise GossipIgnore("block is not the first valid block for this slot and proposer")
 
+    # [IGNORE] The block's parent has been seen (via gossip or non-gossip sources)
+    # (MAY be queued until parent is retrieved)
+    if block.parent_root not in store.blocks:
+        raise GossipIgnore("block's parent has not been seen")
+
+    # [New in Bellatrix]
+    parent_payload_status = PAYLOAD_STATUS_NOT_VALIDATED
+    if block.parent_root in block_payload_statuses:
+        parent_payload_status = block_payload_statuses[block.parent_root]
+
+    # [New in Bellatrix]
+    if block.parent_root not in store.block_states:
+        # The parent has no post-state, so `is_execution_enabled` uses the
+        # justified checkpoint (always imported). Merge-complete is monotonic.
+        if is_execution_enabled(store.block_states[store.justified_checkpoint.root], block.body):
+            if parent_payload_status == PAYLOAD_STATUS_NOT_VALIDATED:
+                # [REJECT] The block's parent failed validation and its execution payload is optimistic
+                raise GossipReject("block's parent is invalid and its payload is optimistic")
+
+            # [IGNORE] The block's parent failed validation and its execution payload is processed
+            raise GossipIgnore("block's parent is invalid and its payload is processed")
+
+        # [Modified in Bellatrix]
+        # [REJECT] The block's parent passes validation
+        raise GossipReject("block's parent is invalid and execution is not enabled")
+
+    state = store.block_states[get_head(store).root]
+
     # [REJECT] The proposer index is a valid validator index
     if block.proposer_index >= len(state.validators):
         raise GossipReject("proposer index out of range")
@@ -157,38 +183,16 @@ def validate_beacon_block_gossip(
     if not bls.Verify(proposer.pubkey, signing_root, signed_beacon_block.signature):
         raise GossipReject("invalid proposer signature")
 
-    # [IGNORE] The block's parent has been seen (via gossip or non-gossip sources)
-    # (MAY be queued until parent is retrieved)
-    if block.parent_root not in store.blocks:
-        raise GossipIgnore("block's parent has not been seen")
-
     # [New in Bellatrix]
     if is_execution_enabled(state, block.body):
         # [REJECT] The block's execution payload timestamp is correct with respect to the slot
         if execution_payload.timestamp != compute_time_at_slot(state, block.slot):
             raise GossipReject("incorrect execution payload timestamp")
 
-        parent_payload_status = PAYLOAD_STATUS_NOT_VALIDATED
-        if block.parent_root in block_payload_statuses:
-            parent_payload_status = block_payload_statuses[block.parent_root]
-
-        if block.parent_root not in store.block_states:
-            if parent_payload_status == PAYLOAD_STATUS_NOT_VALIDATED:
-                # [REJECT] The block's parent failed validation and its execution payload is optimistic
-                raise GossipReject("block's parent is invalid and its payload is optimistic")
-
-            # [IGNORE] The block's parent failed validation and its execution payload is processed
-            raise GossipIgnore("block's parent is invalid and its payload is processed")
-
         # [IGNORE] The block's parent passed validation but its execution payload is invalid
         if parent_payload_status == PAYLOAD_STATUS_INVALIDATED:
             raise GossipIgnore("block's parent is valid and its payload is invalid")
 
-    # [REJECT] The block's parent passes validation
-    elif block.parent_root not in store.block_states:
-        # [Modified in Bellatrix]
-        raise GossipReject("block's parent is invalid and execution is not enabled")
-
     # [REJECT] The block is from a higher slot than its parent
     if block.slot <= store.blocks[block.parent_root].slot:
         raise GossipReject("block is not from a higher slot than its parent")

specs/capella/p2p-interface.md

@@ -107,7 +107,6 @@ unconditionally enabled after The Merge, which happens before Capella.
 def validate_beacon_block_gossip(
     seen: Seen,
     store: Store,
-    state: BeaconState,
     signed_beacon_block: SignedBeaconBlock,
     current_time_ms: Uint64,
     block_payload_statuses: Dict[Root, PayloadValidationStatus],
@@ -136,26 +135,11 @@ def validate_beacon_block_gossip(
     if proposer_slot_key in seen.proposer_slots:
         raise GossipIgnore("block is not the first valid block for this slot and proposer")
 
-    # [REJECT] The proposer index is a valid validator index
-    if block.proposer_index >= len(state.validators):
-        raise GossipReject("proposer index out of range")
-
-    # [REJECT] The proposer signature is valid
-    proposer = state.validators[block.proposer_index]
-    domain = get_domain(state, DOMAIN_BEACON_PROPOSER, compute_epoch_at_slot(block.slot))
-    signing_root = compute_signing_root(block, domain)
-    if not bls.Verify(proposer.pubkey, signing_root, signed_beacon_block.signature):
-        raise GossipReject("invalid proposer signature")
-
     # [IGNORE] The block's parent has been seen (via gossip or non-gossip sources)
     # (MAY be queued until parent is retrieved)
     if block.parent_root not in store.blocks:
         raise GossipIgnore("block's parent has not been seen")
 
-    # [REJECT] The block's execution payload timestamp is correct with respect to the slot
-    if execution_payload.timestamp != compute_time_at_slot(state, block.slot):
-        raise GossipReject("incorrect execution payload timestamp")
-
     parent_payload_status = PAYLOAD_STATUS_NOT_VALIDATED
     if block.parent_root in block_payload_statuses:
         parent_payload_status = block_payload_statuses[block.parent_root]
@@ -172,6 +156,23 @@ def validate_beacon_block_gossip(
     if parent_payload_status == PAYLOAD_STATUS_INVALIDATED:
         raise GossipIgnore("block's parent is valid and its payload is invalid")
 
+    state = store.block_states[get_head(store).root]
+
+    # [REJECT] The proposer index is a valid validator index
+    if block.proposer_index >= len(state.validators):
+        raise GossipReject("proposer index out of range")
+
+    # [REJECT] The proposer signature is valid
+    proposer = state.validators[block.proposer_index]
+    domain = get_domain(state, DOMAIN_BEACON_PROPOSER, compute_epoch_at_slot(block.slot))
+    signing_root = compute_signing_root(block, domain)
+    if not bls.Verify(proposer.pubkey, signing_root, signed_beacon_block.signature):
+        raise GossipReject("invalid proposer signature")
+
+    # [REJECT] The block's execution payload timestamp is correct with respect to the slot
+    if execution_payload.timestamp != compute_time_at_slot(state, block.slot):
+        raise GossipReject("incorrect execution payload timestamp")
+
     # [REJECT] The block is from a higher slot than its parent
     if block.slot <= store.blocks[block.parent_root].slot:
         raise GossipReject("block is not from a higher slot than its parent")
@@ -198,12 +199,12 @@ def validate_beacon_block_gossip(
 
 The `bls_to_execution_change` topic is used solely for propagating signed BLS to
 execution change messages on the network. Signed messages are sent in their
-entirety. The `state` parameter is the head state.
+entirety.
 
 ```python
 def validate_bls_to_execution_change_gossip(
     seen: Seen,
-    state: BeaconState,
+    store: Store,
     signed_bls_to_execution_change: SignedBLSToExecutionChange,
     current_time_ms: Uint64,
 ) -> None:
@@ -216,7 +217,7 @@ def validate_bls_to_execution_change_gossip(
 
     # [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 - state.genesis_time * 1000
+    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:
@@ -226,6 +227,8 @@ def validate_bls_to_execution_change_gossip(
     if validator_index in seen.bls_to_execution_change_indices:
         raise GossipIgnore("already seen BLS to execution change for this validator")
 
+    state = store.block_states[get_head(store).root]
+
     # [REJECT] The validator index is valid
     if validator_index >= len(state.validators):
         raise GossipReject("validator index out of range")