If no code exists at the BEACON_ROOTS_ADDRESS, make it so.

eth/vm/forks/cancun/__init__.py

@@ -4,6 +4,9 @@
 
 from eth.abc import (
     BlockHeaderAPI,
+    ChainContextAPI,
+    ChainDatabaseAPI,
+    ConsensusContextAPI,
     StateAPI,
 )
 from eth.rlp.blocks import (
@@ -24,6 +27,7 @@
 )
 from .constants import (
     BEACON_ROOTS_ADDRESS,
+    BEACON_ROOTS_CONTRACT_CODE,
     HISTORY_BUFFER_LENGTH,
 )
 from .headers import (
@@ -49,6 +53,24 @@ class CancunVM(ShanghaiVM):
     )
     configure_header = configure_cancun_header
 
+    def __init__(
+        self,
+        header: BlockHeaderAPI,
+        chaindb: ChainDatabaseAPI,
+        chain_context: ChainContextAPI,
+        consensus_context: ConsensusContextAPI,
+    ) -> None:
+        super().__init__(header, chaindb, chain_context, consensus_context)
+        self.chaindb = chaindb
+        self.chain_context = chain_context
+        self.consensus_context = consensus_context
+        self._initial_header = header
+
+        # If there exists no code at the BEACON_ROOTS_ADDRESS, set the code as defined
+        # in EIP-4788.
+        if self.state.get_code(BEACON_ROOTS_ADDRESS) == b"":
+            self.state.set_code(BEACON_ROOTS_ADDRESS, BEACON_ROOTS_CONTRACT_CODE)
+
     @classmethod
     def block_preprocessing(cls, state: StateAPI, header: BlockHeaderAPI) -> None:
         super().block_preprocessing(state, header)

eth/vm/forks/cancun/constants.py

@@ -2,3 +2,4 @@
 BEACON_ROOTS_ADDRESS = (
     b'\x00\x0f=\xf6\xd72\x80~\xf11\x9f\xb7\xb8\xbb\x85"\xd0\xbe\xac\x02'
 )
+BEACON_ROOTS_CONTRACT_CODE = b"3s\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\x14`MW` 6\x14`$W__\xfd[_5\x80\x15`IWb\x00\x1f\xff\x81\x06\x90\x81T\x14`<W__\xfd[b\x00\x1f\xff\x01T_R` _\xf3[__\xfd[b\x00\x1f\xffB\x06B\x81U_5\x90b\x00\x1f\xff\x01U\x00"  # noqa: E501