Mempool Tx simultaneous input detection using Bitcoin Core RPC and Rust
As a developer working with Bitcoin, you are probably familiar with the difficulties of managing a memory pool of signed but unconfirmed transactions. One such problem is detecting that other users are simultaneously using channels in these events. In this article, we will look at how to implement such authentication using the REST API (RPC) of Bitcoin Core and Rust.
Background
In Bitcoin, a transaction consists of a list of inputs and outputs. Each input is associated with a unique address, and each output is associated with multiple inputs via the Coinbase field in the transaction header. To detect concurrent input usage, we need to track events that update the memory pool.
Rust code
To solve this problem, we will write a Rust client that interacts with Bitcoin Core’s RPC API. We define a “Mempool” structure to represent the state of the mempool and an “Event” structure to store event data.
use bitcoin::core::{Network, Version};
use bitcoin::rest::Client;
#[derive(Network, Debug)]
struct Mempool {
transactions: Vec,
}
impl Mempool {
fn get(&self) -> Result, bitcoin::error::Error> {
Client::new("
let but txs = vec![];
for transaction self.transactions.iter() {
txs.push(transaction.clone());
}
ok (thanks)
}
}
struct Event {
inputs: Vec,
outputs: Vec
}
Input and output structures
We define two structures for representing input and output data.
#[output(debug)]
input struct {
address: Stroka,
}
#[output(debug)]
struct Output {
index: u16,
meaning: u256,
}
Deployment to customers
To interact with Bitcoin Core’s RPC API, we’ll create a client that can retrieve the state of the memory pool. We use bitcoin::rest box to connect to the server and send requests.
use bitcoin::core::{Network, Version};
use bitcoin::rest::Client;
impl Mempool {
fn get(&self) -> Result, bitcoin::error::Error> {
let client = Client::new("
let but txs = vec![];
for transaction self.transactions.iter() {
txs.push(transaction.clone());
}
ok (thanks)
}
}
Detection of simultaneous use
To detect the simultaneous use of an input, we replay events and check whether any output is associated with multiple inputs. If such a link is found, it means that the channel was used in a second transaction.
impl Mempool {
fn detect_concurrent_use(&self) -> bool {
for transaction self.transactions.iter() {
for output transaction.outputs.iter() {
if output.value != 0 && !output.index.is_null() {
let input data = event.input data.clone();
for input inputs.iter() {
let index = input.address.string();
for second_input outputs.iter().filter(|o| o.address == input.address) {
if other_input.value != 0 && !other_input.index.is_null() {
returns the truth;
}
}
}
}
}
}
incorrect
}
}
Testing and running the code
To test our code, we’ll create a simple test suite using a “load test”. We define a “Mempool” structure with a “get” method that returns an empty vector.