fix(rpc): cap request gas limit if not set (#1858)

Co-authored-by: Dan Cline <6798349+Rjected@users.noreply.github.com>

crates/rpc/rpc-types/src/eth/call.rs

@@ -28,3 +28,12 @@ pub struct CallRequest {
     /// AccessList
     pub access_list: Option<AccessList>,
 }
+
+impl CallRequest {
+    /// Returns the configured fee cap, if any.
+    ///
+    /// The returns `gas_price` (legacy) if set or `max_fee_per_gas` (EIP1559)
+    pub fn fee_cap(&self) -> Option<U256> {
+        self.gas_price.or(self.max_fee_per_gas)
+    }
+}

crates/rpc/rpc/src/eth/api/call.rs

@@ -68,7 +68,10 @@ where
         // impls and providers <https://github.com/foundry-rs/foundry/issues/4388>
         cfg.disable_block_gas_limit = true;
 
-        let env = build_call_evm_env(cfg, block, request)?;
+        let request_gas = request.gas;
+
+        let mut env = build_call_evm_env(cfg, block, request)?;
+
         let mut db = SubState::new(State::new(state));
 
         // apply state overrides
@@ -76,6 +79,23 @@ where
             apply_state_overrides(state_overrides, &mut db)?;
         }
 
+        if request_gas.is_none() && env.tx.gas_price > U256::ZERO {
+            // no gas limit was provided in the request, so we need to cap the request's gas limit
+            let mut allowance = db.basic(env.tx.caller)?.map(|acc| acc.balance).unwrap_or_default();
+
+            // subtract transferred value
+            allowance = allowance
+                .checked_sub(env.tx.value)
+                .ok_or_else(|| InvalidTransactionError::InsufficientFunds)?;
+
+            // cap the gas limit
+            if let Ok(gas_limit) =
+                allowance.checked_div(env.tx.gas_price).unwrap_or_default().try_into()
+            {
+                env.tx.gas_limit = gas_limit;
+            }
+        }
+
         transact(&mut db, env)
     }
 

crates/rpc/rpc/src/eth/revm_utils.rs

@@ -57,7 +57,9 @@ where
     Ok((res, evm.env))
 }
 
-/// Creates a new [Env] to be used for executing the [CallRequest] in `eth_call`
+/// Creates a new [Env] to be used for executing the [CallRequest] in `eth_call`.
+///
+/// Note: this does _not_ access the Database to check the sender.
 pub(crate) fn build_call_evm_env(
     cfg: CfgEnv,
     block: BlockEnv,
@@ -68,6 +70,9 @@ pub(crate) fn build_call_evm_env(
 }
 
 /// Configures a new [TxEnv]  for the [CallRequest]
+///
+/// All [TxEnv] fields are derived from the given [CallRequest], if fields are `None`, they fall
+/// back to the [BlockEnv]'s settings.
 pub(crate) fn create_txn_env(block_env: &BlockEnv, request: CallRequest) -> EthResult<TxEnv> {
     let CallRequest {
         from,