Update EIP-6493: Use Variant[S] for type safety

EIPS/eip-6493.md

@@ -121,36 +121,145 @@ class TransactionSignature(StableContainer[MAX_TRANSACTION_SIGNATURE_FIELDS]):
 class SignedTransaction(Container):
     payload: TransactionPayload
     signature: TransactionSignature
+```
+
+Valid transaction types can be defined using [EIP-7495](./eip-7495.md) `Variant`.
+
+```python
+class ReplayableTransactionPayload(Variant[TransactionPayload]):
+    nonce: uint64
+    max_fee_per_gas: uint256
+    gas: uint64
+    to: Optional[ExecutionAddress]
+    value: uint256
+    input_: ByteList[MAX_CALLDATA_SIZE]
+
+class ReplayableSignedTransaction(SignedTransaction):
+    payload: ReplayableTransactionPayload
+    signature: TransactionSignature
+
+class LegacyTransactionPayload(Variant[TransactionPayload]):
+    nonce: uint64
+    max_fee_per_gas: uint256
+    gas: uint64
+    to: Optional[ExecutionAddress]
+    value: uint256
+    input_: ByteList[MAX_CALLDATA_SIZE]
+    type_: TransactionType
+
+class LegacySignedTransaction(SignedTransaction):
+    payload: LegacyTransactionPayload
+    signature: TransactionSignature
+
+class Eip2930TransactionPayload(Variant[TransactionPayload]):
+    nonce: uint64
+    max_fee_per_gas: uint256
+    gas: uint64
+    to: Optional[ExecutionAddress]
+    value: uint256
+    input_: ByteList[MAX_CALLDATA_SIZE]
+    type_: TransactionType
+    access_list: List[AccessTuple, MAX_ACCESS_LIST_SIZE]
+
+class Eip2930SignedTransaction(SignedTransaction):
+    payload: Eip2930TransactionPayload
+    signature: TransactionSignature
+
+class Eip1559TransactionPayload(Variant[TransactionPayload]):
+    nonce: uint64
+    max_fee_per_gas: uint256
+    gas: uint64
+    to: Optional[ExecutionAddress]
+    value: uint256
+    input_: ByteList[MAX_CALLDATA_SIZE]
+    type_: TransactionType
+    access_list: List[AccessTuple, MAX_ACCESS_LIST_SIZE]
+    max_priority_fee_per_gas: uint256
+
+class Eip1559SignedTransaction(SignedTransaction):
+    payload: Eip1559TransactionPayload
+    signature: TransactionSignature
+
+class Eip4844TransactionPayload(Variant[TransactionPayload]):
+    nonce: uint64
+    max_fee_per_gas: uint256
+    gas: uint64
+    to: ExecutionAddress
+    value: uint256
+    input_: ByteList[MAX_CALLDATA_SIZE]
+    type_: TransactionType
+    access_list: List[AccessTuple, MAX_ACCESS_LIST_SIZE]
+    max_priority_fee_per_gas: uint256
+    max_fee_per_blob_gas: uint256
+    blob_versioned_hashes: List[VersionedHash, MAX_BLOB_COMMITMENTS_PER_BLOCK]
+
+class Eip4844SignedTransaction(SignedTransaction):
+    payload: Eip4844TransactionPayload
+    signature: TransactionSignature
+
+class BasicTransactionPayload(Variant[TransactionPayload]):
+    nonce: uint64
+    max_fee_per_gas: uint256
+    gas: uint64
+    to: Optional[ExecutionAddress]
+    value: uint256
+    input_: ByteList[MAX_CALLDATA_SIZE]
+    type_: TransactionType
+    access_list: List[AccessTuple, MAX_ACCESS_LIST_SIZE]
+    max_priority_fee_per_gas: uint256
+
+class BasicSignedTransaction(SignedTransaction):
+    payload: BasicTransactionPayload
+    signature: TransactionSignature
+
+class BlobTransactionPayload(Variant[TransactionPayload]):
+    nonce: uint64
+    max_fee_per_gas: uint256
+    gas: uint64
+    to: ExecutionAddress
+    value: uint256
+    input_: ByteList[MAX_CALLDATA_SIZE]
+    type_: TransactionType
+    access_list: List[AccessTuple, MAX_ACCESS_LIST_SIZE]
+    max_priority_fee_per_gas: uint256
+    max_fee_per_blob_gas: uint256
+    blob_versioned_hashes: List[VersionedHash, MAX_BLOB_COMMITMENTS_PER_BLOCK]
 
-def check_transaction_supported(tx: SignedTransaction):
-    if tx.payload.max_fee_per_blob_gas is not None:
-        assert tx.payload.blob_versioned_hashes is not None
-        assert tx.payload.max_priority_fee_per_gas is not None
-        assert tx.payload.to is not None
-    else:
-        assert tx.payload.blob_versioned_hashes is None
-
-    if tx.payload.max_priority_fee_per_gas is not None:
-        assert tx.payload.access_list is not None
-
-    if tx.payload.type_ != TRANSACTION_TYPE_SSZ:
-        if tx.payload.max_fee_per_blob_gas is not None:
-            assert tx.payload.type_ == TRANSACTION_TYPE_EIP4844
-        elif tx.payload.max_priority_fee_per_gas is not None:
-            assert tx.payload.type_ == TRANSACTION_TYPE_EIP1559
-        elif tx.payload.access_list is not None:
-            assert tx.payload.type_ == TRANSACTION_TYPE_EIP2930
-        else:
-            assert tx.payload.type_ == TRANSACTION_TYPE_LEGACY or tx.payload.type_ is None
+class BlobSignedTransaction(SignedTransaction):
+    payload: BlobTransactionPayload
+    signature: TransactionSignature
+
+class AnySignedTransaction(OneOf[SignedTransaction]):
+    @classmethod
+    def select_variant(cls, value: SignedTransaction) -> Type[SignedTransaction]:
+        if value.payload.type_ == TRANSACTION_TYPE_SSZ:
+            if value.payload.blob_versioned_hashes is not None:
+                return BlobSignedTransaction
+            return BasicSignedTransaction
+
+        if value.payload.type_ == TRANSACTION_TYPE_EIP4844:
+            return Eip4844SignedTransaction
+
+        if value.payload.type_ == TRANSACTION_TYPE_EIP1559:
+            return Eip1559SignedTransaction
+
+        if value.payload.type_ == TRANSACTION_TYPE_EIP2930:
+            return Eip2930SignedTransaction
+
+        if value.payload.type_ == TRANSACTION_TYPE_LEGACY:
+            return LegacySignedTransaction
+
+        assert value.payload.type_ is None
+        return ReplayableSignedTransaction
 ```
 
 Future specifications MAY:
 
 - Add fields to the end of `TransactionPayload` and `TransactionSignature`
 - Convert existing fields to `Optional`
-- Relax the validation rules in `check_transaction_supported`
+- Define new `Variant` types and update `select_variant` logic
 
-Such changes [do not affect](./eip-7495.md) how existing transactions serialize, merkleize, or validate.
+Such changes [do not affect](./eip-7495.md) how existing transactions serialize or merkleize.
 
 ![Transaction merkleization](../assets/eip-6493/transaction.png)
 
@@ -226,9 +335,8 @@ def ecdsa_recover_from_address(signature: ByteVector[ECDSA_SIGNATURE_SIZE],
     uncompressed = public_key.serialize(compressed=False)
     return ExecutionAddress(keccak(uncompressed[1:])[12:])
 
-def validate_transaction(tx: SignedTransaction,
+def validate_transaction(tx: AnySignedTransaction,
                          chain_id: ChainId):
-    check_transaction_supported(tx)
     ecdsa_validate_signature(tx.signature.ecdsa_signature)
     assert tx.signature.from_ == ecdsa_recover_from_address(
         tx.signature.ecdsa_signature,
@@ -294,12 +402,39 @@ class Receipt(StableContainer[MAX_RECEIPT_FIELDS]):
     status: Optional[boolean]
 ```
 
+Valid receipt types can be defined using [EIP-7495](./eip-7495.md) `Variant`.
+
+```python
+class HomesteadReceipt(Variant[Receipt]):
+    root: Hash32
+    gas_used: uint64
+    contract_address: Optional[ExecutionAddress]
+    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
+    logs: List[Log, MAX_LOGS_PER_RECEIPT]
+
+class BasicReceipt(Variant[Receipt]):
+    gas_used: uint64
+    contract_address: Optional[ExecutionAddress]
+    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
+    logs: List[Log, MAX_LOGS_PER_RECEIPT]
+    status: boolean
+
+class AnyReceipt(OneOf[Receipt]):
+    @classmethod
+    def select_variant(cls, value: Receipt) -> Type[Receipt]:
+        if value.status is not None:
+            return BasicReceipt
+
+        return HomesteadReceipt
+```
+
 Future specifications MAY:
 
 - Add fields to the end of `Receipt`
 - Convert existing fields to `Optional`
+- Define new `Variant` types and update `select_variant` logic
 
-Such changes [do not affect](./eip-7495.md) how existing receipts serialize, merkleize, or validate.
+Such changes [do not affect](./eip-7495.md) how existing receipts serialize or merkleize.
 
 ![Receipt merkleization](../assets/eip-6493/receipt.png)
 
@@ -360,7 +495,7 @@ Mixing the chain ID into the `TransactionDomainData` further allows dropping the
 
 ### What about EIP-2718 transaction types?
 
-All SSZ transactions (including future ones) share the single [EIP-2718](./eip-2718.md) transaction type `TRANSACTION_TYPE_SSZ`. Future features can introduce new optional fields as well as new allowed combination of optional fields, as determined by `check_transaction_supported`.
+All SSZ transactions (including future ones) share the single [EIP-2718](./eip-2718.md) transaction type `TRANSACTION_TYPE_SSZ`. Future features can introduce new optional fields as well as new allowed combination of optional fields, as determined by `select_variant` in `AnySignedTransaction`.
 
 This also reduces combinatorial explosion; for example, the `access_list` property could be made optional for all SSZ transactions without having to double the number of defined transaction types.
 

assets/eip-6493/convert.py

@@ -4,11 +4,11 @@
 from ssz_types import *
 
 def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
-                                   chain_id: ChainId) -> SignedTransaction:
+                                   chain_id: ChainId) -> AnySignedTransaction:
     type_ = pre_bytes[0]
 
     if type_ == 0x03:  # EIP-4844
-        pre = decode(pre_bytes[1:], Eip4844SignedTransaction)
+        pre = decode(pre_bytes[1:], Eip4844SignedRlpTransaction)
         assert pre.chain_id == chain_id
 
         assert pre.signature_y_parity in (0, 1)
@@ -19,8 +19,8 @@ def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
         )
         from_ = ecdsa_recover_from_address(ecdsa_signature, compute_eip4844_sig_hash(pre))
 
-        return SignedTransaction(
-            payload=TransactionPayload(
+        return Eip4844SignedTransaction(
+            payload=Eip4844TransactionPayload(
                 nonce=pre.nonce,
                 max_fee_per_gas=pre.max_fee_per_gas,
                 gas=pre.gas_limit,
@@ -43,7 +43,7 @@ def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
         )
 
     if type_ == 0x02:  # EIP-1559
-        pre = decode(pre_bytes[1:], Eip1559SignedTransaction)
+        pre = decode(pre_bytes[1:], Eip1559SignedRlpTransaction)
         assert pre.chain_id == chain_id
 
         assert pre.signature_y_parity in (0, 1)
@@ -54,8 +54,8 @@ def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
         )
         from_ = ecdsa_recover_from_address(ecdsa_signature, compute_eip1559_sig_hash(pre))
 
-        return SignedTransaction(
-            payload=TransactionPayload(
+        return Eip1559SignedTransaction(
+            payload=Eip1559TransactionPayload(
                 nonce=pre.nonce,
                 max_fee_per_gas=pre.max_fee_per_gas,
                 gas=pre.gas_limit,
@@ -76,7 +76,7 @@ def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
         )
 
     if type_ == 0x01:  # EIP-2930
-        pre = decode(pre_bytes[1:], Eip2930SignedTransaction)
+        pre = decode(pre_bytes[1:], Eip2930SignedRlpTransaction)
         assert pre.chainId == chain_id
 
         assert pre.signatureYParity in (0, 1)
@@ -87,8 +87,8 @@ def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
         )
         from_ = ecdsa_recover_from_address(ecdsa_signature, compute_eip2930_sig_hash(pre))
 
-        return SignedTransaction(
-            payload=TransactionPayload(
+        return Eip2930SignedTransaction(
+            payload=Eip2930TransactionPayload(
                 nonce=pre.nonce,
                 max_fee_per_gas=pre.gasPrice,
                 gas=pre.gasLimit,
@@ -108,7 +108,7 @@ def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
         )
 
     if 0xc0 <= type_ <= 0xfe:  # Legacy
-        pre = decode(pre_bytes, LegacySignedTransaction)
+        pre = decode(pre_bytes, LegacySignedRlpTransaction)
 
         if pre.v not in (27, 28):  # EIP-155
             assert pre.v in (2 * chain_id + 35, 2 * chain_id + 36)
@@ -119,15 +119,31 @@ def upgrade_rlp_transaction_to_ssz(pre_bytes: bytes,
         )
         from_ = ecdsa_recover_from_address(ecdsa_signature, compute_legacy_sig_hash(pre))
 
-        return SignedTransaction(
-            payload=TransactionPayload(
+        if (pre.v not in (27, 28)):
+            return LegacySignedTransaction(
+                payload=LegacyTransactionPayload(
+                    nonce=pre.nonce,
+                    max_fee_per_gas=pre.gasprice,
+                    gas=pre.startgas,
+                    to=ExecutionAddress(pre.to) if len(pre.to) > 0 else None,
+                    value=pre.value,
+                    input_=pre.data,
+                    type_=TRANSACTION_TYPE_LEGACY,
+                ),
+                signature=TransactionSignature(
+                    from_=from_,
+                    ecdsa_signature=ecdsa_signature,
+                ),
+            )
+
+        return ReplayableSignedTransaction(
+            payload=ReplayableTransactionPayload(
                 nonce=pre.nonce,
                 max_fee_per_gas=pre.gasprice,
                 gas=pre.startgas,
                 to=ExecutionAddress(pre.to) if len(pre.to) > 0 else None,
                 value=pre.value,
                 input_=pre.data,
-                type_=TRANSACTION_TYPE_LEGACY if (pre.v not in (27, 28)) else None,
             ),
             signature=TransactionSignature(
                 from_=from_,
@@ -152,7 +168,7 @@ def compute_contract_address(from_: ExecutionAddress,
 
 def upgrade_rlp_receipt_to_ssz(pre_bytes: bytes,
                                prev_cumulative_gas_used: uint64,
-                               transaction: SignedTransaction) -> Receipt:
+                               transaction: AnySignedTransaction) -> AnyReceipt:
     type_ = pre_bytes[0]
 
     if type_ in (0x03, 0x02, 0x01):  # EIP-4844, EIP-1559, EIP-2930
@@ -162,14 +178,26 @@ def upgrade_rlp_receipt_to_ssz(pre_bytes: bytes,
     else:
         assert False
 
-    if len(pre.post_state_or_status) == 32:
-        root = pre.post_state_or_status
-        status = None
-    else:
-        root = None
+    if len(pre.post_state_or_status) != 32:
         status = len(pre.post_state_or_status) > 0 and pre.post_state_or_status[0] != 0
 
-    return Receipt(
+        return BasicReceipt(
+            gas_used=pre.cumulative_gas_used - prev_cumulative_gas_used,
+            contract_address=compute_contract_address(
+                transaction.signature.from_,
+                transaction.payload.nonce,
+            ) if transaction.payload.to is None else None,
+            logs_bloom=pre.logs_bloom,
+            logs=[Log(
+                address=log[0],
+                topics=log[1],
+                data=log[2],
+            ) for log in pre.logs],
+            status=status,
+        )
+
+    root = pre.post_state_or_status
+    return HomesteadReceipt(
         root=root,
         gas_used=pre.cumulative_gas_used - prev_cumulative_gas_used,
         contract_address=compute_contract_address(
@@ -182,12 +210,11 @@ def upgrade_rlp_receipt_to_ssz(pre_bytes: bytes,
             topics=log[1],
             data=log[2],
         ) for log in pre.logs],
-        status=status,
     )
 
 def upgrade_rlp_receipts_to_ssz(pre_bytes_list: PyList[bytes],
                                 chain_id: ChainId,
-                                transactions: PyList[SignedTransaction]) -> PyList[Receipt]:
+                                transactions: PyList[AnySignedTransaction]) -> PyList[AnyReceipt]:
     receipts = []
     cumulative_gas_used = 0
     for i, pre_bytes in enumerate(pre_bytes_list):