feat(l1): reject contract senders at mempool admission (EIP-3607)

crates/blockchain/blockchain.rs

@@ -57,7 +57,7 @@ use constants::{
 };
 use error::MempoolError;
 use error::{ChainError, InvalidBlockError};
-use ethrex_common::constants::{EMPTY_TRIE_HASH, MIN_BASE_FEE_PER_BLOB_GAS};
+use ethrex_common::constants::{EMPTY_KECCACK_HASH, EMPTY_TRIE_HASH, MIN_BASE_FEE_PER_BLOB_GAS};
 
 use crossbeam::channel::{self as cb, TryRecvError, select};
 // Re-export stateless validation functions for backwards compatibility
@@ -66,6 +66,7 @@ use ethrex_common::types::EIP4844Transaction;
 use ethrex_common::types::block_access_list::BlockAccessList;
 use ethrex_common::types::block_execution_witness::ExecutionWitness;
 use ethrex_common::types::fee_config::FeeConfig;
+use ethrex_common::types::is_eip7702_delegation;
 use ethrex_common::types::{
     AccountInfo, AccountState, AccountUpdate, Block, BlockHash, BlockHeader, BlockNumber,
     ChainConfig, Code, Receipt, Transaction, WrappedEIP4844Transaction, validate_block_body,
@@ -2491,6 +2492,20 @@ impl Blockchain {
                 return Err(MempoolError::NonceTooLow);
             }
 
+            // EIP-3607: reject txs from senders with deployed code, unless the
+            // code is an EIP-7702 delegation designation (the account is still
+            // an EOA in spirit, just pointing at delegate code).
+            if sender_acc_info.code_hash != *EMPTY_KECCACK_HASH {
+                let is_delegation = match self.storage.get_account_code(sender_acc_info.code_hash) {
+                    Ok(Some(code)) => is_eip7702_delegation(code.bytecode.as_ref()),
+                    Ok(None) => false,
+                    Err(e) => return Err(e.into()),
+                };
+                if !is_delegation {
+                    return Err(MempoolError::SenderIsContract);
+                }
+            }
+
             let tx_cost = tx
                 .cost_without_base_fee()
                 .ok_or(MempoolError::InvalidTxGasvalues)?;

crates/blockchain/error.rs

@@ -83,6 +83,8 @@ pub enum MempoolError {
     TxMaxInitCodeSizeError,
     #[error("Transaction max data size exceeded")]
     TxMaxDataSizeError,
+    #[error("Transaction sender is a contract account (EIP-3607)")]
+    SenderIsContract,
     #[error("Transaction gas limit exceeded")]
     TxGasLimitExceededError,
     #[error(

crates/common/types/account.rs

@@ -191,6 +191,19 @@ pub fn code_hash(code: &Bytes, crypto: &dyn Crypto) -> H256 {
     H256(crypto.keccak256(code.as_ref()))
 }
 
+/// EIP-7702 delegation designation: an EOA whose code is `0xef0100 || address`.
+/// See <https://eips.ethereum.org/EIPS/eip-7702>.
+pub const EIP7702_DELEGATION_PREFIX: [u8; 3] = [0xef, 0x01, 0x00];
+/// Total byte length of an EIP-7702 delegation designation: 3-byte prefix
+/// plus the 20-byte target address.
+pub const EIP7702_DELEGATED_CODE_LEN: usize = 23;
+
+/// Returns true iff `code` is a valid EIP-7702 delegation designation
+/// (exactly 23 bytes, prefixed with `0xef0100`).
+pub fn is_eip7702_delegation(code: &[u8]) -> bool {
+    code.len() == EIP7702_DELEGATED_CODE_LEN && code.starts_with(&EIP7702_DELEGATION_PREFIX)
+}
+
 impl RLPEncode for AccountInfo {
     fn encode(&self, buf: &mut dyn bytes::BufMut) {
         Encoder::new(buf)
@@ -396,4 +409,49 @@ mod test {
                 .unwrap()
         )
     }
+
+    #[test]
+    fn test_is_eip7702_delegation_valid() {
+        // 0xef0100 || 20-byte address
+        let mut code = Vec::with_capacity(23);
+        code.extend_from_slice(&EIP7702_DELEGATION_PREFIX);
+        code.extend_from_slice(&[0x42; 20]);
+        assert!(is_eip7702_delegation(&code));
+    }
+
+    #[test]
+    fn test_is_eip7702_delegation_rejects_empty() {
+        assert!(!is_eip7702_delegation(&[]));
+    }
+
+    #[test]
+    fn test_is_eip7702_delegation_rejects_short() {
+        // Prefix only, no address.
+        assert!(!is_eip7702_delegation(&EIP7702_DELEGATION_PREFIX));
+    }
+
+    #[test]
+    fn test_is_eip7702_delegation_rejects_long() {
+        // Correct prefix but 24 bytes total.
+        let mut code = Vec::with_capacity(24);
+        code.extend_from_slice(&EIP7702_DELEGATION_PREFIX);
+        code.extend_from_slice(&[0x42; 21]);
+        assert!(!is_eip7702_delegation(&code));
+    }
+
+    #[test]
+    fn test_is_eip7702_delegation_rejects_wrong_prefix() {
+        // Right length, wrong magic.
+        let mut code = Vec::with_capacity(23);
+        code.extend_from_slice(&[0xef, 0x01, 0x01]); // off by one in the last prefix byte
+        code.extend_from_slice(&[0x42; 20]);
+        assert!(!is_eip7702_delegation(&code));
+    }
+
+    #[test]
+    fn test_is_eip7702_delegation_rejects_arbitrary_contract_code() {
+        // Real contract code starting with anything else.
+        let code = vec![0x60, 0x60, 0x60, 0x40, 0x52 /* ... */];
+        assert!(!is_eip7702_delegation(&code));
+    }
 }