Blockchain tests support: Fix tx receipt rlp encoding (#680)

- Encode `cumulative_gas_used` instead of `gas_used`
- Support tx receipt format for pre Byzantium

test/state/state.cpp

@@ -3,6 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #include "state.hpp"
+#include "../utils/stdx/utility.hpp"
 #include "errors.hpp"
 #include "host.hpp"
 #include "rlp.hpp"
@@ -212,7 +213,8 @@ std::variant<TransactionReceipt, std::error_code> transition(State& state, const
     std::erase_if(state.get_accounts(),
         [](const std::pair<const address, Account>& p) noexcept { return p.second.destructed; });
 
-    auto receipt = TransactionReceipt{tx.type, result.status_code, gas_used, host.take_logs(), {}};
+    // Cumulative gas used is unknown in this scope.
+    TransactionReceipt receipt{tx.type, result.status_code, gas_used, {}, host.take_logs(), {}, {}};
 
     // Cannot put it into constructor call because logs are std::moved from host instance.
     receipt.logs_bloom_filter = compute_bloom_filter(receipt.logs);
@@ -273,10 +275,24 @@ std::variant<TransactionReceipt, std::error_code> transition(State& state, const
 
 [[nodiscard]] bytes rlp_encode(const TransactionReceipt& receipt)
 {
-    const auto prefix = receipt.type == Transaction::Type::eip1559 ? bytes{0x02} : bytes{};
-    return prefix + rlp::encode_tuple(receipt.status == EVMC_SUCCESS,
-                        static_cast<uint64_t>(receipt.gas_used),
-                        bytes_view(receipt.logs_bloom_filter), receipt.logs);
+    if (receipt.post_state.has_value())
+    {
+        assert(receipt.type == Transaction::Type::legacy);
+
+        return rlp::encode_tuple(receipt.post_state.value(),
+            static_cast<uint64_t>(receipt.cumulative_gas_used),
+            bytes_view(receipt.logs_bloom_filter), receipt.logs);
+    }
+    else
+    {
+        const auto prefix = receipt.type == Transaction::Type::legacy ?
+                                bytes{} :
+                                bytes{stdx::to_underlying(receipt.type)};
+
+        return prefix + rlp::encode_tuple(receipt.status == EVMC_SUCCESS,
+                            static_cast<uint64_t>(receipt.cumulative_gas_used),
+                            bytes_view(receipt.logs_bloom_filter), receipt.logs);
+    }
 }
 
 }  // namespace evmone::state

test/state/state.hpp

@@ -134,13 +134,30 @@ struct Log
     std::vector<hash256> topics;
 };
 
+/// Transaction Receipt
+///
+/// This struct is used in two contexts:
+/// 1. As the formally specified, RLP-encode transaction receipt included in the Ethereum blocks.
+/// 2. As the internal representation of the transaction execution result.
+/// These both roles share most, but not all the information. There are some fields that cannot be
+/// assigned in the single transaction execution context. There are also fields that are not a part
+/// of the RLP-encoded transaction receipts.
+/// TODO: Consider splitting the struct into two based on the duality explained above.
 struct TransactionReceipt
 {
     Transaction::Type type = Transaction::Type::legacy;
     evmc_status_code status = EVMC_INTERNAL_ERROR;
+
+    /// Amount of gas used by this transaction.
     int64_t gas_used = 0;
+
+    /// Amount of gas used by this and previous transactions in the block.
+    int64_t cumulative_gas_used = 0;
     std::vector<Log> logs;
     BloomFilter logs_bloom_filter;
+
+    /// Root hash of the state after this transaction. Used only in old pre-Byzantium transactions.
+    std::optional<bytes32> post_state;
 };
 
 /// Finalize state after applying a "block" of transactions.

test/t8n/t8n.cpp

@@ -145,6 +145,9 @@ int main(int argc, const char* argv[])
                         j_receipt["transactionHash"] = hex0x(computed_tx_hash);
                         j_receipt["gasUsed"] = hex0x(static_cast<uint64_t>(receipt.gas_used));
                         cumulative_gas_used += receipt.gas_used;
+                        receipt.cumulative_gas_used = cumulative_gas_used;
+                        if (rev < EVMC_BYZANTIUM)
+                            receipt.post_state = state::mpt_hash(state.get_accounts());
                         j_receipt["cumulativeGasUsed"] = hex0x(cumulative_gas_used);
 
                         j_receipt["blockHash"] = hex0x(bytes32{});

test/unittests/state_mpt_hash_test.cpp

@@ -188,7 +188,7 @@ TEST(state_mpt_hash, legacy_and_eip1559_receipt_three_logs_no_logs)
     TransactionReceipt receipt0{};
     receipt0.type = evmone::state::Transaction::Type::legacy;
     receipt0.status = EVMC_SUCCESS;
-    receipt0.gas_used = 0x24522;
+    receipt0.cumulative_gas_used = 0x24522;
 
     Log l0;
     l0.addr = 0x84bf5c35c54a994c72ff9d8b4cca8f5034153a2c_address;
@@ -238,9 +238,44 @@ TEST(state_mpt_hash, legacy_and_eip1559_receipt_three_logs_no_logs)
     TransactionReceipt receipt1{};
     receipt1.type = evmone::state::Transaction::Type::eip1559;
     receipt1.status = EVMC_SUCCESS;
-    receipt1.gas_used = 0x2cd9b;
+    receipt1.cumulative_gas_used = 0x2cd9b;
     receipt1.logs_bloom_filter = compute_bloom_filter(receipt1.logs);
 
     EXPECT_EQ(mpt_hash(std::array{receipt0, receipt1}),
         0x7199a3a86010634dc205a1cdd6ec609f70b954167583cb3acb6a2e3057916016_bytes32);
 }
+
+TEST(state_mpt_hash, pre_byzantium_receipt)
+{
+    // Block taken from Ethereum mainnet
+    // https://etherscan.io/txs?block=4276370
+
+    using namespace evmone::state;
+
+    TransactionReceipt receipt0{
+        .type = Transaction::Type::legacy,
+        .cumulative_gas_used = 0x8323,
+        .logs = {},
+        .logs_bloom_filter = compute_bloom_filter(receipt0.logs),
+        .post_state = 0x4a8f9db452b100f9ec85830785b2d1744c3e727561c334c4f18022daa113290a_bytes32,
+    };
+
+    TransactionReceipt receipt1{
+        .type = Transaction::Type::legacy,
+        .cumulative_gas_used = 0x10646,
+        .logs = {},
+        .logs_bloom_filter = compute_bloom_filter(receipt1.logs),
+        .post_state = 0xb14ab7c32b3e126591731850976a15e2359c1f3628f1b0ff37776c210b9cadb8_bytes32,
+    };
+
+    TransactionReceipt receipt2{
+        .type = Transaction::Type::legacy,
+        .cumulative_gas_used = 0x1584e,
+        .logs = {},
+        .logs_bloom_filter = compute_bloom_filter(receipt2.logs),
+        .post_state = 0x7bda915deb201cae321d31028d322877e8fb98264db3ffcbfec7ea7b9b2106b1_bytes32,
+    };
+
+    EXPECT_EQ(mpt_hash(std::array{receipt0, receipt1, receipt2}),
+        0x8a4fa43a95939b06ad13ce8cd08e026ae6e79ea3c5fc80c732d252e2769ce778_bytes32);
+}