how to stop listening for gossiped transaction (restrict access to the TXpool)?

Question

In outer node, i want to create a node that does not listen to gossiped transaction or in other words the transaction pool should not add any transaction from other peers, the only way to add transactions is done by the local node himself using pool.submit_one() method.

PS: even when closing all the rpc ports, its still adds transactions and i assume its low level using libp2p.

Answer 1

Yes, transactions are gossiped via libp2p networking. If you don't want to receive/send transactions via libp2p networking you need to change the following code:

let (network, system_rpc_tx, tx_handler_controller, network_starter, sync_service) =
        sc_service::build_network(sc_service::BuildNetworkParams {
        config: &config,
        client: client.clone(),
        transaction_pool: transaction_pool.clone(),
        spawn_handle: task_manager.spawn_handle(),
        import_queue,
        block_announce_validator_builder: None,
        warp_sync_params: Some(WarpSyncParams::WithProvider(warp_sync)),
    })?;

transaction_pool is the thing you need to change. You will need to provide your own implementation of the TransactionPool trait:

struct DummyTxPool;

impl<B> sc_network_transactions::config::TransactionPool<Block::Hash, B>
    for DummyTxPool
where
    B: BlockT,
{
    fn transactions(&self) -> Vec<(H, B::Extrinsic)> {
        // Don't propagate any transactions
        vec![]
    }

    fn hash_of(&self, tx: &B::Extrinsic) -> H {
        sp_runtime::traits::HashFor::<B>::hash_of(tx)
    }

    fn import(&self, _: B::Extrinsic) -> TransactionImportFuture {
        // We just ignore the import request.
        async { TransactionImport::None }.boxed()
    }

    fn on_broadcasted(&self, _: HashMap<H, Vec<String>>) {}

    fn transaction(&self, _: &H) -> Option<B::Extrinsic> {
        None
    }
}

Then you need to set transaction_pool to DummyTxPool. If you maybe want to still propagate your own local transactions, you need to modify transactions to return the ones you want to propagate.