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truncate `Peers` response further (#3007)

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Alfredo Garcia 2021-11-02 19:21:54 -03:00 committed by GitHub
parent e4b0af73da
commit 4d600a0fc1
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1 changed files with 15 additions and 6 deletions
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21
zebrad/src/components/inbound.rs
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@ -40,6 +40,13 @@ type InboundBlockDownloads = BlockDownloads<Timeout<Outbound>, Timeout<BlockVeri
pub type NetworkSetupData = (Outbound, Arc<std::sync::Mutex<AddressBook>>, Mempool);
/// A bitcoin protocol constant that will hold the max number of peers
/// we can return in response to a `Peers` request.
const MAX_ADDR: usize = 1000; // bitcoin protocol constant
/// A security parameter to return only 1/3 of available addresses as a
/// response to a `Peers` request.
const FRAC_OF_AVAILABLE_ADDRESS: f64 = 1. / 3.;
/// Tracks the internal state of the [`Inbound`] service during network setup.
pub enum Setup {
/// Waiting for network setup to complete.
@ -248,10 +255,9 @@ impl Service<zn::Request> for Inbound {
if let Setup::Initialized { address_book, .. } = &self.network_setup {
// # Security
//
// We could truncate the list to try to not reveal our entire
// peer set. But because we don't monitor repeated requests,
// this wouldn't actually achieve anything, because a crawler
// could just repeatedly query it.
// We truncate the list to not reveal our entire peer set in one call.
// But we don't monitor repeated requests and the results are shuffled,
// a crawler could just send repeated queries and get the full list.
//
// # Correctness
//
@ -262,8 +268,11 @@ impl Service<zn::Request> for Inbound {
// Send a sanitized response
let mut peers = peers.sanitized();
const MAX_ADDR: usize = 1000; // bitcoin protocol constant
peers.truncate(MAX_ADDR);
// Truncate the list
let truncate_at = MAX_ADDR
.min((peers.len() as f64 * FRAC_OF_AVAILABLE_ADDRESS).ceil() as usize);
peers.truncate(truncate_at);
if !peers.is_empty() {
async { Ok(zn::Response::Peers(peers)) }.boxed()