TxPool will not pack tx with invalid chainId

nimbus/core/tx_pool/tx_info.nim

@@ -45,6 +45,9 @@ type
       ## Implied disposal, typically implied by greater nonces (fallback value)
       "implied disposal"
 
+    txInfoChainIdMismatch = ##\
+      ## Tx chainId does not match with network chainId
+      "chainId mismatch"
     # ------ Miscellaneous errors ----------------------------------------------
 
     txInfoErrUnspecified = ##\

nimbus/core/tx_pool/tx_tasks/tx_packer.nim

@@ -27,7 +27,7 @@ import
   ../../../transaction,
   ../../../vm_state,
   ../../../vm_types,
-  ".."/[tx_chain, tx_desc, tx_item, tx_tabs, tx_tabs/tx_status],
+  ".."/[tx_chain, tx_desc, tx_item, tx_tabs, tx_tabs/tx_status, tx_info],
   "."/[tx_bucket, tx_classify]
 
 type
@@ -186,6 +186,10 @@ proc vmExecGrabItem(pst: TxPackerStateRef; item: TxItemRef): Result[bool,void]
     xp = pst.xp
     vmState = xp.chain.vmState
 
+  if not item.tx.validateChainId(xp.chain.com.chainId):
+    discard xp.txDB.dispose(item, txInfoChainIdMismatch)
+    return ok(false) # continue with next account
+
   # EIP-4844
   if pst.numBlobPerBlock + item.tx.versionedHashes.len > MAX_BLOBS_PER_BLOCK:
     return err() # stop collecting

nimbus/transaction.nim

@@ -191,6 +191,19 @@ proc signTransaction*(tx: Transaction, privateKey: PrivateKey, chainId: ChainId,
   result.R = UInt256.fromBytesBE(sig[0..31])
   result.S = UInt256.fromBytesBE(sig[32..63])
 
+# deriveChainId derives the chain id from the given v parameter
+func deriveChainId*(v: int64, chainId: ChainId): ChainId =
+  if v == 27 or v == 28:
+    chainId
+  else:
+    ((v - 35) div 2).ChainId
+
+func validateChainId*(tx: Transaction, chainId: ChainId): bool =
+  if tx.txType == TxLegacy:
+    chainId.uint64 == deriveChainId(tx.V, chainId).uint64
+  else:
+    chainId.uint64 == tx.chainId.uint64
+
 func eip1559TxNormalization*(tx: Transaction;
                              baseFee: GasInt): Transaction =
   ## This function adjusts a legacy transaction to EIP-1559 standard. This