Enhance Mempool DoS Protection via Strict Dynamic Payload Size Validation #35486

I apologize in advance for using such rigid terms, you can block me if this is irrelevant or there is no open discussion for c++ code below, thank you and sincere apologies.

Abstract: This proposal introduces a minor optimization to the mempool validation policy to mitigate specific Denial-of-Service (DoS) vectors involving high-frequency, low-fee package submissions. By enforcing tighter constraints on the minimum transaction size relative to its total inputs during the policy check phase, the node can reject non-standard execution paths before they consume excessive CPU validation time. This secondary validation path acts as an early-stage filter, reducing the processing overhead on peer-to-peer transaction propagation under heavy loads.

C++ Implementation:

#include <vector> #include <cstdint>

struct TransactionData { int64_t tx_weight; int64_t total_input_value; };

class MempoolPolicyFilter { public: bool EvaluateTransactionPolicy(const TransactionData& tx) { int64_t min_allowable_weight = (tx.total_input_value > 0) ? 64 : 0; if (tx.tx_weight < min_allowable_weight) { return false; } return true; }

void ProcessMempoolBatch(std::vector<TransactionData>& tx_batch) {
    std::vector<TransactionData> valid_txs;
    valid_txs.reserve(tx_batch.size());
    
    for (size_t i = 0; i < tx_batch.size(); ++i) {
        if (EvaluateTransactionPolicy(tx_batch[i])) {
            valid_txs.push_back(tx_batch[i]);
        }
    }
    
    tx_batch = std::move(valid_txs);
}

};