Merge pull request #1165 from carver/rpc-eth-call

add chain.get_transaction_result and rpc eth_call

Author: carver

eth/chains/base.py

@@ -250,6 +250,13 @@ def get_canonical_transaction(self, transaction_hash: Hash32) -> BaseTransaction
     #
     # Execution API
     #
+    @abstractmethod
+    def get_transaction_result(
+            self,
+            transaction: Union[BaseTransaction, SpoofTransaction],
+            at_header: BlockHeader) -> bytes:
+        raise NotImplementedError("Chain classes must implement this method")
+
     @abstractmethod
     def estimate_gas(
             self,
@@ -550,6 +557,20 @@ def create_unsigned_transaction(self,
     #
     # Execution API
     #
+    def get_transaction_result(
+            self,
+            transaction: Union[BaseTransaction, SpoofTransaction],
+            at_header: BlockHeader) -> bytes:
+        """
+        Return the result of running the given transaction.
+        This is referred to as a `call()` in web3.
+        """
+        with self.get_vm(at_header).state_in_temp_block() as state:
+            computation = state.costless_execute_transaction(transaction)
+
+        computation.raise_if_error()
+        return computation.output
+
     def estimate_gas(
             self,
             transaction: Union[BaseTransaction, SpoofTransaction],

eth/utils/spoof.py

@@ -1,3 +1,7 @@
+from cytoolz import (
+    merge,
+)
+
 from eth.constants import (
     DEFAULT_SPOOF_V,
     DEFAULT_SPOOF_R,
@@ -45,6 +49,11 @@ def __getattr__(self, attr: str) -> Union[int, Callable, bytes]:
         else:
             return getattr(self.spoof_target, attr)
 
+    def copy(self, **kwargs):
+        new_target = self.spoof_target.copy(**kwargs)
+        new_overrides = merge(self.overrides, kwargs)
+        return type(self)(new_target, **new_overrides)
+
 
 class SpoofTransaction(SpoofAttributes):
     def __init__(self, transaction: BaseTransaction, **overrides: Any) -> None:

eth/vm/computation.py

@@ -163,6 +163,15 @@ def is_error(self) -> bool:
         """
         return not self.is_success
 
+    def raise_if_error(self) -> None:
+        """
+        If there was an error during computation, raise it as an exception immediately.
+
+        :raise VMError:
+        """
+        if self._error is not None:
+            raise self._error
+
     @property
     def should_burn_gas(self) -> bool:
         """

eth/vm/forks/frontier/state.py

@@ -46,8 +46,7 @@ def validate_transaction(self, transaction):
 
     def build_evm_message(self, transaction):
 
-        transaction_context = self.get_transaction_context(transaction)
-        gas_fee = transaction.gas * transaction_context.gas_price
+        gas_fee = transaction.gas * transaction.gas_price
 
         # Buy Gas
         self.vm_state.account_db.delta_balance(transaction.sender, -1 * gas_fee)
@@ -99,7 +98,7 @@ def build_evm_message(self, transaction):
 
     def build_computation(self, message, transaction):
         """Apply the message to the VM."""
-        transaction_context = self.get_transaction_context(transaction)
+        transaction_context = self.vm_state.get_transaction_context(transaction)
         if message.is_create:
             is_collision = self.vm_state.account_db.account_has_code_or_nonce(
                 message.storage_address

eth/vm/state.py

@@ -2,6 +2,7 @@
     ABC,
     abstractmethod
 )
+import contextlib
 import logging
 from typing import (  # noqa: F401
     Type,
@@ -223,21 +224,45 @@ def apply_transaction(self, transaction):
     def get_transaction_executor(self):
         return self.transaction_executor(self)
 
+    def costless_execute_transaction(self, transaction):
+        with self.override_transaction_context(gas_price=transaction.gas_price):
+            free_transaction = transaction.copy(gas_price=0)
+            return self.execute_transaction(free_transaction)
+
+    @contextlib.contextmanager
+    def override_transaction_context(self, gas_price):
+        original_context = self.get_transaction_context
+
+        def get_custom_transaction_context(transaction):
+            custom_transaction = transaction.copy(gas_price=gas_price)
+            return original_context(custom_transaction)
+
+        self.get_transaction_context = get_custom_transaction_context
+        try:
+            yield
+        finally:
+            self.get_transaction_context = original_context
+
     @abstractmethod
-    def execute_transaction(self):
+    def execute_transaction(self, transaction):
         raise NotImplementedError()
 
+    @abstractmethod
+    def validate_transaction(self, transaction):
+        raise NotImplementedError
 
-class BaseTransactionExecutor(ABC):
-    def __init__(self, vm_state):
-        self.vm_state = vm_state
-
-    def get_transaction_context(self, transaction):
-        return self.vm_state.get_transaction_context_class()(
+    @classmethod
+    def get_transaction_context(cls, transaction):
+        return cls.get_transaction_context_class()(
             gas_price=transaction.gas_price,
             origin=transaction.sender,
         )
 
+
+class BaseTransactionExecutor(ABC):
+    def __init__(self, vm_state):
+        self.vm_state = vm_state
+
     def __call__(self, transaction):
         valid_transaction = self.validate_transaction(transaction)
         message = self.build_evm_message(valid_transaction)

setup.py

@@ -14,7 +14,7 @@
         "lru-dict>=1.1.6",
         "py-ecc>=1.4.2,<2.0.0",
         "pyethash>=0.1.27,<1.0.0",
-        "rlp>=1.0.1,<2.0.0",
+        "rlp>=1.0.2,<2.0.0",
         "trie>=1.3.5,<2.0.0",
     ],
     # The eth-extra sections is for libraries that the evm does not

tests/conftest.py

@@ -105,7 +105,7 @@ def funded_address_initial_balance():
 
 
 @pytest.fixture
-def chain_with_block_validation(base_db, funded_address, funded_address_initial_balance):
+def chain_with_block_validation(base_db, genesis_state):
     """
     Return a Chain object containing just the genesis block.
 
@@ -133,14 +133,6 @@ def chain_with_block_validation(base_db, funded_address, funded_address_initial_
         "transaction_root": decode_hex("56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421"),  # noqa: E501
         "uncles_hash": decode_hex("1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347")  # noqa: E501
     }
-    genesis_state = {
-        funded_address: {
-            "balance": funded_address_initial_balance,
-            "nonce": 0,
-            "code": b"",
-            "storage": {}
-        }
-    }
     klass = Chain.configure(
         __name__='TestChain',
         vm_configuration=(
@@ -156,12 +148,28 @@ def import_block_without_validation(chain, block):
     return super(type(chain), chain).import_block(block, perform_validation=False)
 
 
+@pytest.fixture
+def base_genesis_state(funded_address, funded_address_initial_balance):
+    return {
+        funded_address: {
+            'balance': funded_address_initial_balance,
+            'nonce': 0,
+            'code': b'',
+            'storage': {},
+        }
+    }
+
+
+@pytest.fixture
+def genesis_state(base_genesis_state):
+    return base_genesis_state
+
+
 @pytest.fixture(params=[Chain, MiningChain])
 def chain_without_block_validation(
         request,
         base_db,
-        funded_address,
-        funded_address_initial_balance):
+        genesis_state):
     """
     Return a Chain object containing just the genesis block.
 
@@ -183,6 +191,7 @@ def chain_without_block_validation(
         vm_configuration=(
             (constants.GENESIS_BLOCK_NUMBER, SpuriousDragonVMForTesting),
         ),
+        network_id=1337,
         **overrides,
     )
     genesis_params = {
@@ -196,13 +205,5 @@ def chain_without_block_validation(
         'extra_data': constants.GENESIS_EXTRA_DATA,
         'timestamp': 1501851927,
     }
-    genesis_state = {
-        funded_address: {
-            'balance': funded_address_initial_balance,
-            'nonce': 0,
-            'code': b'',
-            'storage': {},
-        }
-    }
     chain = klass.from_genesis(base_db, genesis_params, genesis_state)
     return chain

tests/core/chain-object/test_contract_call.py

@@ -0,0 +1,149 @@
+from cytoolz import (
+    assoc,
+)
+from tests.core.helpers import (
+    new_transaction,
+)
+
+from eth_utils import (
+    decode_hex,
+    function_signature_to_4byte_selector,
+    to_bytes,
+)
+import pytest
+
+from eth.exceptions import (
+    InvalidInstruction,
+    OutOfGas,
+)
+
+
+@pytest.fixture
+def chain(chain_with_block_validation):
+    return chain_with_block_validation
+
+
+@pytest.fixture
+def simple_contract_address():
+    return b'\x88' * 20
+
+
+@pytest.fixture
+def genesis_state(base_genesis_state, simple_contract_address):
+    """
+    Includes runtime bytecode of compiled Solidity:
+
+        pragma solidity ^0.4.24;
+
+        contract GetValues {
+            function getMeaningOfLife() public pure returns (uint256) {
+                return 42;
+            }
+            function getGasPrice() public view returns (uint256) {
+                return tx.gasprice;
+            }
+            function getBalance() public view returns (uint256) {
+                return msg.sender.balance;
+            }
+            function doRevert() public pure {
+                revert("always reverts");
+            }
+            function useLotsOfGas() public view {
+                uint size;
+                for (uint i = 0; i < 2**255; i++){
+                    assembly {
+                        size := extcodesize(0)
+                    }
+                }
+            }
+        }
+    """
+    return assoc(
+        base_genesis_state,
+        simple_contract_address,
+        {
+            'balance': 0,
+            'nonce': 0,
+            'code': decode_hex('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'),  # noqa: E501
+            'storage': {},
+        },
+    )
+
+
+def uint256_to_bytes(uint):
+    return to_bytes(uint).rjust(32, b'\0')
+
+
+@pytest.mark.parametrize(
+    'signature, gas_price, expected',
+    (
+        (
+            'getMeaningOfLife()',
+            0,
+            uint256_to_bytes(42),
+        ),
+        (
+            'getGasPrice()',
+            0,
+            uint256_to_bytes(0),
+        ),
+        (
+            'getGasPrice()',
+            9,
+            uint256_to_bytes(9),
+        ),
+        (
+            # make sure that whatever voodoo is used to execute a call, the balance is not inflated
+            'getBalance()',
+            1,
+            uint256_to_bytes(0),
+        ),
+    ),
+)
+def test_get_transaction_result(
+        chain,
+        simple_contract_address,
+        signature,
+        gas_price,
+        expected):
+
+    function_selector = function_signature_to_4byte_selector(signature)
+    call_txn = new_transaction(
+        chain.get_vm(),
+        b'\xff' * 20,
+        simple_contract_address,
+        gas_price=gas_price,
+        data=function_selector,
+    )
+    result_bytes = chain.get_transaction_result(call_txn, chain.get_canonical_head())
+    assert result_bytes == expected
+
+
+@pytest.mark.parametrize(
+    'signature, expected',
+    (
+        (
+            'doRevert()',
+            InvalidInstruction,
+        ),
+        (
+            'useLotsOfGas()',
+            OutOfGas,
+        ),
+    ),
+)
+def test_get_transaction_result_revert(
+        chain,
+        simple_contract_address,
+        signature,
+        expected):
+
+    function_selector = function_signature_to_4byte_selector(signature)
+    call_txn = new_transaction(
+        chain.get_vm(),
+        b'\xff' * 20,
+        simple_contract_address,
+        data=function_selector,
+    )
+    with pytest.raises(expected):
+        chain.get_transaction_result(call_txn, chain.get_canonical_head())