feat: introduce gas_floor_base_cost for EIP-7623 compliance (#101)

* feat: introduce gas_floor_base_cost for EIP-7623 compliance

* fix: replace simple arithmetic operations with saturating_* analogs for gas calculations

* chore: remove gas_floor_base_cost constant

Author: aleksuss

evm/src/gasometer/mod.rs

@@ -343,10 +343,29 @@ impl<'config> Gasometer<'config> {
     /// - [EIP-2028](https://eips.ethereum.org/EIPS/eip-2028)
     /// - [EIP-7623](https://eips.ethereum.org/EIPS/eip-7623)
     #[must_use]
+    #[allow(clippy::as_conversions)] // NOTE: in that context usize->u64 `as_conversions` is safe
     pub const fn intrinsic_gas_and_gas_floor(cost: TransactionCost, config: &Config) -> (u64, u64) {
+        const fn floor_gas_calc(
+            config: &Config,
+            zero_data_len: usize,
+            non_zero_data_len: usize,
+        ) -> u64 {
+            if config.has_floor_gas {
+                // According to EIP-2028: non-zero byte = 16, zero-byte = 4
+                // According to EIP-7623: tokens_in_calldata = zero_bytes_in_calldata + nonzero_bytes_in_calldata * 4
+                let tokens_in_calldata = non_zero_data_len
+                    .saturating_mul(4)
+                    .saturating_add(zero_data_len) as u64;
+
+                tokens_in_calldata
+                    .saturating_mul(config.total_cost_floor_per_token)
+                    .saturating_add(config.gas_transaction_call)
+            } else {
+                0
+            }
+        }
+
         match cost {
-            // NOTE: in that context usize->u64 `as_conversions` is safe
-            #[allow(clippy::as_conversions)]
             TransactionCost::Call {
                 zero_data_len,
                 non_zero_data_len,
@@ -355,52 +374,72 @@ impl<'config> Gasometer<'config> {
                 authorization_list_len,
             } => {
                 #[deny(clippy::let_and_return)]
-                let cost = config.gas_transaction_call
-                    + zero_data_len as u64 * config.gas_transaction_zero_data
-                    + non_zero_data_len as u64 * config.gas_transaction_non_zero_data
-                    + access_list_address_len as u64 * config.gas_access_list_address
-                    + access_list_storage_len as u64 * config.gas_access_list_storage_key
-                    + authorization_list_len as u64 * config.gas_per_empty_account_cost;
-
-                let floor_gas = if config.has_floor_gas {
-                    // According to EIP-2028: non-zero byte = 16, zero-byte = 4
-                    // According to EIP-7623: tokens_in_calldata = zero_bytes_in_calldata + nonzero_bytes_in_calldata * 4
-                    let tokens_in_calldata = (zero_data_len + non_zero_data_len * 4) as u64;
-                    tokens_in_calldata * config.total_cost_floor_per_token
-                        + config.gas_transaction_call
-                } else {
-                    0
-                };
+                let cost = config
+                    .gas_transaction_call
+                    .saturating_add(
+                        config
+                            .gas_transaction_zero_data
+                            .saturating_mul(zero_data_len as u64),
+                    )
+                    .saturating_add(
+                        config
+                            .gas_transaction_non_zero_data
+                            .saturating_mul(non_zero_data_len as u64),
+                    )
+                    .saturating_add(
+                        config
+                            .gas_access_list_address
+                            .saturating_mul(access_list_address_len as u64),
+                    )
+                    .saturating_add(
+                        config
+                            .gas_access_list_storage_key
+                            .saturating_mul(access_list_storage_len as u64),
+                    )
+                    .saturating_add(
+                        config
+                            .gas_per_empty_account_cost
+                            .saturating_mul(authorization_list_len as u64),
+                    );
+                let floor_gas = floor_gas_calc(config, zero_data_len, non_zero_data_len);
 
                 (cost, floor_gas)
             }
-            // NOTE: in that context usize->u64 `as_conversions` is safe
-            #[allow(clippy::as_conversions)]
             TransactionCost::Create {
                 zero_data_len,
                 non_zero_data_len,
                 access_list_address_len,
                 access_list_storage_len,
                 initcode_cost,
             } => {
-                let mut cost = config.gas_transaction_create
-                    + zero_data_len as u64 * config.gas_transaction_zero_data
-                    + non_zero_data_len as u64 * config.gas_transaction_non_zero_data
-                    + access_list_address_len as u64 * config.gas_access_list_address
-                    + access_list_storage_len as u64 * config.gas_access_list_storage_key;
+                let mut cost = config
+                    .gas_transaction_create
+                    .saturating_add(
+                        config
+                            .gas_transaction_zero_data
+                            .saturating_mul(zero_data_len as u64),
+                    )
+                    .saturating_add(
+                        config
+                            .gas_transaction_non_zero_data
+                            .saturating_mul(non_zero_data_len as u64),
+                    )
+                    .saturating_add(
+                        config
+                            .gas_access_list_address
+                            .saturating_mul(access_list_address_len as u64),
+                    )
+                    .saturating_add(
+                        config
+                            .gas_access_list_storage_key
+                            .saturating_mul(access_list_storage_len as u64),
+                    );
+
                 if config.max_initcode_size.is_some() {
-                    cost += initcode_cost;
+                    cost = cost.saturating_add(initcode_cost);
                 }
 
-                let floor_gas = if config.has_floor_gas {
-                    // According to EIP-2028: non-zero byte = 16, zero-byte = 4
-                    // According to EIP-7623: tokens_in_calldata = zero_bytes_in_calldata + nonzero_bytes_in_calldata * 4
-                    let tokens_in_calldata = (zero_data_len + non_zero_data_len * 4) as u64;
-                    tokens_in_calldata * config.total_cost_floor_per_token
-                        + config.gas_transaction_call
-                } else {
-                    0
-                };
+                let floor_gas = floor_gas_calc(config, zero_data_len, non_zero_data_len);
 
                 (cost, floor_gas)
             }

evm/src/runtime/mod.rs

@@ -173,7 +173,7 @@ pub struct Config {
     /// Gas paid for a contract creation transaction.
     pub gas_transaction_create: u64,
     /// Gas paid for a message call transaction.
-    pub gas_transaction_call: u64,
+    pub gas_transaction_call: u64, // TODO: Rename in 3.0.0 because the constant is related not to transaction call only.
     /// Gas paid for zero data in a transaction.
     pub gas_transaction_zero_data: u64,
     /// Gas paid for non-zero data in a transaction.