Update EIP-6110: Spec parse_deposit_data

EIPS/eip-6110.md

@@ -82,6 +82,44 @@ def parse_deposit_data(deposit_event_data) -> bytes[]:
   """
   pass
 
+def is_valid_deposit_event_data(deposit_event_data: bytes) -> bool:
+    """
+    Verifies the layout of the DepositEvent. Returns `False` if the layout is unsupported,
+    `True` if the layout is of the expected format.
+    """
+    if len(deposit_event_data) != 576:
+        return False
+
+    pubkey_offset = int.from_bytes(deposit_event_data[0:32], byteorder='big')
+    withdrawal_credentials_offset = int.from_bytes(deposit_event_data[32:64], byteorder='big')
+    amount_offset = int.from_bytes(deposit_event_data[64:96], byteorder='big')
+    signature_offset = int.from_bytes(deposit_event_data[96:128], byteorder='big')
+    index_offset = int.from_bytes(deposit_event_data[128:160], byteorder='big')
+
+    if (
+        pubkey_offset != 160
+        or withdrawal_credentials_offset != 256
+        or amount_offset != 320
+        or signature_offset != 384
+        or index_offset != 512
+    ):
+        return False
+
+    # These sizes are the sizes of the relevant data
+    pubkey_size = int.from_bytes(deposit_event_data[pubkey_offset:pubkey_offset+32], byteorder='big')
+    withdrawal_credentials_size = int.from_bytes(deposit_event_data[withdrawal_credentials_offset:withdrawal_credentials_offset+32], byteorder='big')
+    amount_size = int.from_bytes(deposit_event_data[amount_offset:amount_offset+32], byteorder='big')
+    signature_size = int.from_bytes(deposit_event_data[signature_offset:signature_offset+32], byteorder='big')
+    index_size = int.from_bytes(deposit_event_data[index_offset:index_offset+32], byteorder='big')
+
+    return (
+        pubkey_size == 48
+        and withdrawal_credentials_size == 32
+        and amount_size == 8
+        and signature_size == 96
+        and index_size == 8
+    )
+
 def event_data_to_deposit_request(deposit_event_data) -> bytes:
     deposit_data = parse_deposit_data(deposit_event_data)
     pubkey = Bytes48(deposit_data[0])
@@ -97,10 +135,11 @@ def get_deposit_request_data(receipts)
     deposit_requests = []
     for receipt in receipts:
         for log in receipt.logs:
-            is_deposit_event = (len(log.topics) > 0 and log.topics[0] == DEPOSIT_EVENT_SIGNATURE_HASH)
-            if log.address == DEPOSIT_CONTRACT_ADDRESS and is_deposit_event:
-                deposit_request = event_data_to_deposit_request(log.data)
-                deposit_requests.append(deposit_request)
+            if log.address == DEPOSIT_CONTRACT_ADDRESS:
+                if len(log.topics) > 0 and log.topics[0] == DEPOSIT_EVENT_SIGNATURE_HASH:
+                    assert is_valid_deposit_event_data(log.data), 'invalid deposit log: unsupported data layout'
+                    deposit_request = event_data_to_deposit_request(log.data)
+                    deposit_requests.append(deposit_request)
 
     # Concatenate list of deposit request data
     return b''.join(deposit_requests)