1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003
// Copyright 2020 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
use super::*;
use crate::kbucket::{Key, KeyBytes};
use instant::Instant;
use libp2p_identity::PeerId;
use std::{
collections::HashMap,
iter::{Cycle, Map, Peekable},
ops::{Index, IndexMut, Range},
};
/// Wraps around a set of [`ClosestPeersIter`], enforcing a disjoint discovery
/// path per configured parallelism according to the S/Kademlia paper.
pub(crate) struct ClosestDisjointPeersIter {
target: KeyBytes,
/// The set of wrapped [`ClosestPeersIter`].
iters: Vec<ClosestPeersIter>,
/// Order in which to query the iterators ensuring fairness across
/// [`ClosestPeersIter::next`] calls.
iter_order: Cycle<Map<Range<usize>, fn(usize) -> IteratorIndex>>,
/// Mapping of contacted peers by their [`PeerId`] to [`PeerState`]
/// containing the corresponding iterator indices as well as the response
/// state.
///
/// Used to track which iterator contacted which peer. See [`PeerState`]
/// for details.
contacted_peers: HashMap<PeerId, PeerState>,
}
impl ClosestDisjointPeersIter {
/// Creates a new iterator with a default configuration.
#[cfg(test)]
pub(crate) fn new<I>(target: KeyBytes, known_closest_peers: I) -> Self
where
I: IntoIterator<Item = Key<PeerId>>,
{
Self::with_config(
ClosestPeersIterConfig::default(),
target,
known_closest_peers,
)
}
/// Creates a new iterator with the given configuration.
pub(crate) fn with_config<I, T>(
config: ClosestPeersIterConfig,
target: T,
known_closest_peers: I,
) -> Self
where
I: IntoIterator<Item = Key<PeerId>>,
T: Into<KeyBytes> + Clone,
{
let peers = known_closest_peers
.into_iter()
.take(K_VALUE.get())
.collect::<Vec<_>>();
let iters = (0..config.parallelism.get())
// NOTE: All [`ClosestPeersIter`] share the same set of peers at
// initialization. The [`ClosestDisjointPeersIter.contacted_peers`]
// mapping ensures that a successful response from a peer is only
// ever passed to a single [`ClosestPeersIter`]. See
// [`ClosestDisjointPeersIter::on_success`] for details.
.map(|_| ClosestPeersIter::with_config(config.clone(), target.clone(), peers.clone()))
.collect::<Vec<_>>();
let iters_len = iters.len();
ClosestDisjointPeersIter {
target: target.into(),
iters,
iter_order: (0..iters_len)
.map(IteratorIndex as fn(usize) -> IteratorIndex)
.cycle(),
contacted_peers: HashMap::new(),
}
}
/// Callback for informing the iterator about a failed request to a peer.
///
/// If the iterator is currently waiting for a result from `peer`,
/// the iterator state is updated and `true` is returned. In that
/// case, after calling this function, `next` should eventually be
/// called again to obtain the new state of the iterator.
///
/// If the iterator is finished, it is not currently waiting for a
/// result from `peer`, or a result for `peer` has already been reported,
/// calling this function has no effect and `false` is returned.
pub(crate) fn on_failure(&mut self, peer: &PeerId) -> bool {
let mut updated = false;
if let Some(PeerState {
initiated_by,
response,
}) = self.contacted_peers.get_mut(peer)
{
updated = self.iters[*initiated_by].on_failure(peer);
if updated {
*response = ResponseState::Failed;
}
for (i, iter) in &mut self.iters.iter_mut().enumerate() {
if IteratorIndex(i) != *initiated_by {
// This iterator never triggered an actual request to the
// given peer - thus ignore the returned boolean.
iter.on_failure(peer);
}
}
}
updated
}
/// Callback for delivering the result of a successful request to a peer.
///
/// Delivering results of requests back to the iterator allows the iterator
/// to make progress. The iterator is said to make progress either when the
/// given `closer_peers` contain a peer closer to the target than any peer
/// seen so far, or when the iterator did not yet accumulate `num_results`
/// closest peers and `closer_peers` contains a new peer, regardless of its
/// distance to the target.
///
/// If the iterator is currently waiting for a result from `peer`,
/// the iterator state is updated and `true` is returned. In that
/// case, after calling this function, `next` should eventually be
/// called again to obtain the new state of the iterator.
///
/// If the iterator is finished, it is not currently waiting for a
/// result from `peer`, or a result for `peer` has already been reported,
/// calling this function has no effect and `false` is returned.
pub(crate) fn on_success<I>(&mut self, peer: &PeerId, closer_peers: I) -> bool
where
I: IntoIterator<Item = PeerId>,
{
let mut updated = false;
if let Some(PeerState {
initiated_by,
response,
}) = self.contacted_peers.get_mut(peer)
{
// Pass the new `closer_peers` to the iterator that first yielded
// the peer.
updated = self.iters[*initiated_by].on_success(peer, closer_peers);
if updated {
// Mark the response as succeeded for future iterators yielding
// this peer. There is no need to keep the `closer_peers`
// around, given that they are only passed to the first
// iterator.
*response = ResponseState::Succeeded;
}
for (i, iter) in &mut self.iters.iter_mut().enumerate() {
if IteratorIndex(i) != *initiated_by {
// Only report the success to all remaining not-first
// iterators. Do not pass the `closer_peers` in order to
// uphold the S/Kademlia disjoint paths guarantee.
//
// This iterator never triggered an actual request to the
// given peer - thus ignore the returned boolean.
iter.on_success(peer, std::iter::empty());
}
}
}
updated
}
pub(crate) fn next(&mut self, now: Instant) -> PeersIterState<'_> {
let mut state = None;
// Ensure querying each iterator at most once.
for _ in 0..self.iters.len() {
let i = self.iter_order.next().expect("Cycle never ends.");
let iter = &mut self.iters[i];
loop {
match iter.next(now) {
PeersIterState::Waiting(None) => {
match state {
Some(PeersIterState::Waiting(Some(_))) => {
// [`ClosestDisjointPeersIter::next`] returns immediately once a
// [`ClosestPeersIter`] yielded a peer. Thus this state is
// unreachable.
unreachable!();
}
Some(PeersIterState::Waiting(None)) => {}
Some(PeersIterState::WaitingAtCapacity) => {
// At least one ClosestPeersIter is no longer at capacity, thus the
// composite ClosestDisjointPeersIter is no longer at capacity.
state = Some(PeersIterState::Waiting(None))
}
Some(PeersIterState::Finished) => {
// `state` is never set to `Finished`.
unreachable!();
}
None => state = Some(PeersIterState::Waiting(None)),
};
break;
}
PeersIterState::Waiting(Some(peer)) => {
match self.contacted_peers.get_mut(&*peer) {
Some(PeerState { response, .. }) => {
// Another iterator already contacted this peer.
let peer = peer.into_owned();
match response {
// The iterator will be notified later whether the given node
// was successfully contacted or not. See
// [`ClosestDisjointPeersIter::on_success`] for details.
ResponseState::Waiting => {}
ResponseState::Succeeded => {
// Given that iterator was not the first to contact the peer
// it will not be made aware of the closer peers discovered
// to uphold the S/Kademlia disjoint paths guarantee. See
// [`ClosestDisjointPeersIter::on_success`] for details.
iter.on_success(&peer, std::iter::empty());
}
ResponseState::Failed => {
iter.on_failure(&peer);
}
}
}
None => {
// The iterator is the first to contact this peer.
self.contacted_peers
.insert(peer.clone().into_owned(), PeerState::new(i));
return PeersIterState::Waiting(Some(Cow::Owned(
peer.into_owned(),
)));
}
}
}
PeersIterState::WaitingAtCapacity => {
match state {
Some(PeersIterState::Waiting(Some(_))) => {
// [`ClosestDisjointPeersIter::next`] returns immediately once a
// [`ClosestPeersIter`] yielded a peer. Thus this state is
// unreachable.
unreachable!();
}
Some(PeersIterState::Waiting(None)) => {}
Some(PeersIterState::WaitingAtCapacity) => {}
Some(PeersIterState::Finished) => {
// `state` is never set to `Finished`.
unreachable!();
}
None => state = Some(PeersIterState::WaitingAtCapacity),
};
break;
}
PeersIterState::Finished => break,
}
}
}
state.unwrap_or(PeersIterState::Finished)
}
/// Finishes all paths containing one of the given peers.
///
/// See [`crate::query::Query::try_finish`] for details.
pub(crate) fn finish_paths<'a, I>(&mut self, peers: I) -> bool
where
I: IntoIterator<Item = &'a PeerId>,
{
for peer in peers {
if let Some(PeerState { initiated_by, .. }) = self.contacted_peers.get_mut(peer) {
self.iters[*initiated_by].finish();
}
}
self.is_finished()
}
/// Immediately transitions the iterator to [`PeersIterState::Finished`].
pub(crate) fn finish(&mut self) {
for iter in &mut self.iters {
iter.finish();
}
}
/// Checks whether the iterator has finished.
pub(crate) fn is_finished(&self) -> bool {
self.iters.iter().all(|i| i.is_finished())
}
/// Note: In the case of no adversarial peers or connectivity issues along
/// any path, all paths return the same result, deduplicated through
/// the `ResultIter`, thus overall `into_result` returns
/// `num_results`. In the case of adversarial peers or connectivity
/// issues `ClosestDisjointPeersIter` tries to return the
/// `num_results` closest benign peers, but as it can not
/// differentiate benign from faulty paths it as well returns faulty
/// peers and thus overall returns more than `num_results` peers.
pub(crate) fn into_result(self) -> impl Iterator<Item = PeerId> {
let result_per_path = self
.iters
.into_iter()
.map(|iter| iter.into_result().map(Key::from));
ResultIter::new(self.target, result_per_path).map(Key::into_preimage)
}
}
/// Index into the [`ClosestDisjointPeersIter`] `iters` vector.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct IteratorIndex(usize);
impl Index<IteratorIndex> for Vec<ClosestPeersIter> {
type Output = ClosestPeersIter;
fn index(&self, index: IteratorIndex) -> &Self::Output {
&self[index.0]
}
}
impl IndexMut<IteratorIndex> for Vec<ClosestPeersIter> {
fn index_mut(&mut self, index: IteratorIndex) -> &mut Self::Output {
&mut self[index.0]
}
}
/// State tracking the iterator that yielded (i.e. tried to contact) a peer. See
/// [`ClosestDisjointPeersIter::on_success`] for details.
#[derive(Debug, PartialEq, Eq)]
struct PeerState {
/// First iterator to yield the peer. Will be notified both of the outcome
/// (success/failure) as well as the closer peers.
initiated_by: IteratorIndex,
/// Keeping track of the response state. In case other iterators later on
/// yield the same peer, they can be notified of the response outcome.
response: ResponseState,
}
impl PeerState {
fn new(initiated_by: IteratorIndex) -> Self {
PeerState {
initiated_by,
response: ResponseState::Waiting,
}
}
}
#[derive(Debug, PartialEq, Eq)]
enum ResponseState {
Waiting,
Succeeded,
Failed,
}
/// Iterator combining the result of multiple [`ClosestPeersIter`] into a single
/// deduplicated ordered iterator.
//
// Note: This operates under the assumption that `I` is ordered.
#[derive(Clone, Debug)]
struct ResultIter<I>
where
I: Iterator<Item = Key<PeerId>>,
{
target: KeyBytes,
iters: Vec<Peekable<I>>,
}
impl<I: Iterator<Item = Key<PeerId>>> ResultIter<I> {
fn new(target: KeyBytes, iters: impl Iterator<Item = I>) -> Self {
ResultIter {
target,
iters: iters.map(Iterator::peekable).collect(),
}
}
}
impl<I: Iterator<Item = Key<PeerId>>> Iterator for ResultIter<I> {
type Item = I::Item;
fn next(&mut self) -> Option<Self::Item> {
let target = &self.target;
self.iters
.iter_mut()
// Find the iterator with the next closest peer.
.fold(Option::<&mut Peekable<_>>::None, |iter_a, iter_b| {
let iter_a = match iter_a {
Some(iter_a) => iter_a,
None => return Some(iter_b),
};
match (iter_a.peek(), iter_b.peek()) {
(Some(next_a), Some(next_b)) => {
if next_a == next_b {
// Remove from one for deduplication.
iter_b.next();
return Some(iter_a);
}
if target.distance(next_a) < target.distance(next_b) {
Some(iter_a)
} else {
Some(iter_b)
}
}
(Some(_), None) => Some(iter_a),
(None, Some(_)) => Some(iter_b),
(None, None) => None,
}
})
// Pop off the next closest peer from that iterator.
.and_then(Iterator::next)
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{K_VALUE, SHA_256_MH};
use libp2p_core::multihash::Multihash;
use quickcheck::*;
use std::collections::HashSet;
use std::iter;
impl Arbitrary for ResultIter<std::vec::IntoIter<Key<PeerId>>> {
fn arbitrary(g: &mut Gen) -> Self {
let target = Target::arbitrary(g).0;
let num_closest_iters = g.gen_range(0..20 + 1);
let peers = random_peers(g.gen_range(0..20 * num_closest_iters + 1), g);
let iters = (0..num_closest_iters).map(|_| {
let num_peers = g.gen_range(0..20 + 1);
let mut peers = g
.choose_multiple(&peers, num_peers)
.cloned()
.map(Key::from)
.collect::<Vec<_>>();
peers.sort_unstable_by_key(|a| target.distance(a));
peers.into_iter()
});
ResultIter::new(target.clone(), iters)
}
fn shrink(&self) -> Box<dyn Iterator<Item = Self>> {
let peers = self
.iters
.clone()
.into_iter()
.flatten()
.collect::<HashSet<_>>()
.into_iter()
.collect::<Vec<_>>();
let iters = self
.iters
.clone()
.into_iter()
.map(|iter| iter.collect::<Vec<_>>())
.collect();
Box::new(ResultIterShrinker {
target: self.target.clone(),
peers,
iters,
})
}
}
struct ResultIterShrinker {
target: KeyBytes,
peers: Vec<Key<PeerId>>,
iters: Vec<Vec<Key<PeerId>>>,
}
impl Iterator for ResultIterShrinker {
type Item = ResultIter<std::vec::IntoIter<Key<PeerId>>>;
/// Return an iterator of [`ResultIter`]s with each of them missing a
/// different peer from the original set.
fn next(&mut self) -> Option<Self::Item> {
// The peer that should not be included.
let peer = self.peers.pop()?;
let iters = self.iters.clone().into_iter().filter_map(|mut iter| {
iter.retain(|p| p != &peer);
if iter.is_empty() {
return None;
}
Some(iter.into_iter())
});
Some(ResultIter::new(self.target.clone(), iters))
}
}
#[derive(Clone, Debug)]
struct ArbitraryPeerId(PeerId);
impl Arbitrary for ArbitraryPeerId {
fn arbitrary(g: &mut Gen) -> ArbitraryPeerId {
let hash: [u8; 32] = core::array::from_fn(|_| u8::arbitrary(g));
let peer_id =
PeerId::from_multihash(Multihash::wrap(SHA_256_MH, &hash).unwrap()).unwrap();
ArbitraryPeerId(peer_id)
}
}
#[derive(Clone, Debug)]
struct Target(KeyBytes);
impl Arbitrary for Target {
fn arbitrary(g: &mut Gen) -> Self {
let peer_id = ArbitraryPeerId::arbitrary(g).0;
Target(Key::from(peer_id).into())
}
}
fn random_peers(n: usize, g: &mut Gen) -> Vec<PeerId> {
(0..n).map(|_| ArbitraryPeerId::arbitrary(g).0).collect()
}
#[test]
fn result_iter_returns_deduplicated_ordered_peer_id_stream() {
fn prop(result_iter: ResultIter<std::vec::IntoIter<Key<PeerId>>>) {
let expected = {
let mut deduplicated = result_iter
.clone()
.iters
.into_iter()
.flatten()
.collect::<HashSet<_>>()
.into_iter()
.map(Key::from)
.collect::<Vec<_>>();
deduplicated.sort_unstable_by(|a, b| {
result_iter
.target
.distance(a)
.cmp(&result_iter.target.distance(b))
});
deduplicated
};
assert_eq!(expected, result_iter.collect::<Vec<_>>());
}
QuickCheck::new().quickcheck(prop as fn(_))
}
#[derive(Debug, Clone)]
struct Parallelism(NonZeroUsize);
impl Arbitrary for Parallelism {
fn arbitrary(g: &mut Gen) -> Self {
Parallelism(NonZeroUsize::new(g.gen_range(1..10)).unwrap())
}
}
#[derive(Debug, Clone)]
struct NumResults(NonZeroUsize);
impl Arbitrary for NumResults {
fn arbitrary(g: &mut Gen) -> Self {
NumResults(NonZeroUsize::new(g.gen_range(1..K_VALUE.get())).unwrap())
}
}
impl Arbitrary for ClosestPeersIterConfig {
fn arbitrary(g: &mut Gen) -> Self {
ClosestPeersIterConfig {
parallelism: Parallelism::arbitrary(g).0,
num_results: NumResults::arbitrary(g).0,
peer_timeout: Duration::from_secs(1),
}
}
}
#[derive(Debug, Clone)]
struct PeerVec(Vec<Key<PeerId>>);
impl Arbitrary for PeerVec {
fn arbitrary(g: &mut Gen) -> Self {
PeerVec(
(0..g.gen_range(1..60u8))
.map(|_| ArbitraryPeerId::arbitrary(g).0)
.map(Key::from)
.collect(),
)
}
}
#[test]
fn s_kademlia_disjoint_paths() {
let now = Instant::now();
let target: KeyBytes = Key::from(PeerId::random()).into();
let mut pool = [0; 12]
.iter()
.map(|_| Key::from(PeerId::random()))
.collect::<Vec<_>>();
pool.sort_unstable_by_key(|a| target.distance(a));
let known_closest_peers = pool.split_off(pool.len() - 3);
let config = ClosestPeersIterConfig {
parallelism: NonZeroUsize::new(3).unwrap(),
num_results: NonZeroUsize::new(3).unwrap(),
..ClosestPeersIterConfig::default()
};
let mut peers_iter =
ClosestDisjointPeersIter::with_config(config, target, known_closest_peers.clone());
////////////////////////////////////////////////////////////////////////
// First round.
for _ in 0..3 {
if let PeersIterState::Waiting(Some(Cow::Owned(peer))) = peers_iter.next(now) {
assert!(known_closest_peers.contains(&Key::from(peer)));
} else {
panic!("Expected iterator to return peer to query.");
}
}
assert_eq!(PeersIterState::WaitingAtCapacity, peers_iter.next(now),);
let response_2 = pool.split_off(pool.len() - 3);
let response_3 = pool.split_off(pool.len() - 3);
// Keys are closer than any of the previous two responses from honest
// node 1 and 2.
let malicious_response_1 = pool.split_off(pool.len() - 3);
// Response from malicious peer 1.
peers_iter.on_success(
known_closest_peers[0].preimage(),
malicious_response_1
.clone()
.into_iter()
.map(|k| *k.preimage()),
);
// Response from peer 2.
peers_iter.on_success(
known_closest_peers[1].preimage(),
response_2.clone().into_iter().map(|k| *k.preimage()),
);
// Response from peer 3.
peers_iter.on_success(
known_closest_peers[2].preimage(),
response_3.clone().into_iter().map(|k| *k.preimage()),
);
////////////////////////////////////////////////////////////////////////
// Second round.
let mut next_to_query = vec![];
for _ in 0..3 {
if let PeersIterState::Waiting(Some(Cow::Owned(peer))) = peers_iter.next(now) {
next_to_query.push(peer)
} else {
panic!("Expected iterator to return peer to query.");
}
}
// Expect a peer from each disjoint path.
assert!(next_to_query.contains(malicious_response_1[0].preimage()));
assert!(next_to_query.contains(response_2[0].preimage()));
assert!(next_to_query.contains(response_3[0].preimage()));
for peer in next_to_query {
peers_iter.on_success(&peer, vec![]);
}
// Mark all remaining peers as succeeded.
for _ in 0..6 {
if let PeersIterState::Waiting(Some(Cow::Owned(peer))) = peers_iter.next(now) {
peers_iter.on_success(&peer, vec![]);
} else {
panic!("Expected iterator to return peer to query.");
}
}
assert_eq!(PeersIterState::Finished, peers_iter.next(now),);
let final_peers: Vec<_> = peers_iter.into_result().collect();
// Expect final result to contain peer from each disjoint path, even
// though not all are among the best ones.
assert!(final_peers.contains(malicious_response_1[0].preimage()));
assert!(final_peers.contains(response_2[0].preimage()));
assert!(final_peers.contains(response_3[0].preimage()));
}
#[derive(Clone)]
struct Graph(HashMap<PeerId, Peer>);
impl std::fmt::Debug for Graph {
fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
fmt.debug_list().entries(self.0.keys()).finish()
}
}
impl Arbitrary for Graph {
fn arbitrary(g: &mut Gen) -> Self {
let mut peer_ids = random_peers(g.gen_range(K_VALUE.get()..200), g)
.into_iter()
.map(|peer_id| (peer_id, Key::from(peer_id)))
.collect::<Vec<_>>();
// Make each peer aware of its direct neighborhood.
let mut peers = peer_ids
.clone()
.into_iter()
.map(|(peer_id, key)| {
peer_ids
.sort_unstable_by(|(_, a), (_, b)| key.distance(a).cmp(&key.distance(b)));
assert_eq!(peer_id, peer_ids[0].0);
let known_peers = peer_ids
.iter()
// Skip itself.
.skip(1)
.take(K_VALUE.get())
.cloned()
.collect::<Vec<_>>();
(peer_id, Peer { known_peers })
})
.collect::<HashMap<_, _>>();
// Make each peer aware of a random set of other peers within the graph.
for (peer_id, peer) in peers.iter_mut() {
g.shuffle(&mut peer_ids);
let num_peers = g.gen_range(K_VALUE.get()..peer_ids.len() + 1);
let mut random_peer_ids = g
.choose_multiple(&peer_ids, num_peers)
// Make sure not to include itself.
.filter(|(id, _)| peer_id != id)
.cloned()
.collect::<Vec<_>>();
peer.known_peers.append(&mut random_peer_ids);
peer.known_peers = std::mem::take(&mut peer.known_peers)
// Deduplicate peer ids.
.into_iter()
.collect::<HashSet<_>>()
.into_iter()
.collect();
}
Graph(peers)
}
}
impl Graph {
fn get_closest_peer(&self, target: &KeyBytes) -> PeerId {
*self
.0
.keys()
.map(|peer_id| (target.distance(&Key::from(*peer_id)), peer_id))
.fold(None, |acc, (distance_b, peer_id_b)| match acc {
None => Some((distance_b, peer_id_b)),
Some((distance_a, peer_id_a)) => {
if distance_a < distance_b {
Some((distance_a, peer_id_a))
} else {
Some((distance_b, peer_id_b))
}
}
})
.expect("Graph to have at least one peer.")
.1
}
}
#[derive(Debug, Clone)]
struct Peer {
known_peers: Vec<(PeerId, Key<PeerId>)>,
}
impl Peer {
fn get_closest_peers(&mut self, target: &KeyBytes) -> Vec<PeerId> {
self.known_peers
.sort_unstable_by(|(_, a), (_, b)| target.distance(a).cmp(&target.distance(b)));
self.known_peers
.iter()
.take(K_VALUE.get())
.map(|(id, _)| id)
.cloned()
.collect()
}
}
enum PeerIterator {
Disjoint(ClosestDisjointPeersIter),
Closest(ClosestPeersIter),
}
impl PeerIterator {
fn next(&mut self, now: Instant) -> PeersIterState<'_> {
match self {
PeerIterator::Disjoint(iter) => iter.next(now),
PeerIterator::Closest(iter) => iter.next(now),
}
}
fn on_success(&mut self, peer: &PeerId, closer_peers: Vec<PeerId>) {
match self {
PeerIterator::Disjoint(iter) => iter.on_success(peer, closer_peers),
PeerIterator::Closest(iter) => iter.on_success(peer, closer_peers),
};
}
fn into_result(self) -> Vec<PeerId> {
match self {
PeerIterator::Disjoint(iter) => iter.into_result().collect(),
PeerIterator::Closest(iter) => iter.into_result().collect(),
}
}
}
/// Ensure [`ClosestPeersIter`] and [`ClosestDisjointPeersIter`] yield same closest peers.
#[test]
fn closest_and_disjoint_closest_yield_same_result() {
fn prop(
target: Target,
graph: Graph,
parallelism: Parallelism,
num_results: NumResults,
) -> TestResult {
if parallelism.0 > num_results.0 {
return TestResult::discard();
}
let target: KeyBytes = target.0;
let closest_peer = graph.get_closest_peer(&target);
let mut known_closest_peers = graph
.0
.iter()
.take(K_VALUE.get())
.map(|(key, _peers)| Key::from(*key))
.collect::<Vec<_>>();
known_closest_peers.sort_unstable_by_key(|a| target.distance(a));
let cfg = ClosestPeersIterConfig {
parallelism: parallelism.0,
num_results: num_results.0,
..ClosestPeersIterConfig::default()
};
let closest = drive_to_finish(
PeerIterator::Closest(ClosestPeersIter::with_config(
cfg.clone(),
target.clone(),
known_closest_peers.clone(),
)),
graph.clone(),
&target,
);
let disjoint = drive_to_finish(
PeerIterator::Disjoint(ClosestDisjointPeersIter::with_config(
cfg,
target.clone(),
known_closest_peers.clone(),
)),
graph,
&target,
);
assert!(
closest.contains(&closest_peer),
"Expected `ClosestPeersIter` to find closest peer.",
);
assert!(
disjoint.contains(&closest_peer),
"Expected `ClosestDisjointPeersIter` to find closest peer.",
);
assert!(
closest.len() == num_results.0.get(),
"Expected `ClosestPeersIter` to find `num_results` closest \
peers."
);
assert!(
disjoint.len() >= num_results.0.get(),
"Expected `ClosestDisjointPeersIter` to find at least \
`num_results` closest peers."
);
if closest.len() > disjoint.len() {
let closest_only = closest.difference(&disjoint).collect::<Vec<_>>();
panic!(
"Expected `ClosestDisjointPeersIter` to find all peers \
found by `ClosestPeersIter`, but it did not find {closest_only:?}.",
);
};
TestResult::passed()
}
fn drive_to_finish(
mut iter: PeerIterator,
mut graph: Graph,
target: &KeyBytes,
) -> HashSet<PeerId> {
let now = Instant::now();
loop {
match iter.next(now) {
PeersIterState::Waiting(Some(peer_id)) => {
let peer_id = peer_id.clone().into_owned();
let closest_peers =
graph.0.get_mut(&peer_id).unwrap().get_closest_peers(target);
iter.on_success(&peer_id, closest_peers);
}
PeersIterState::WaitingAtCapacity | PeersIterState::Waiting(None) => {
panic!("There is never more than one request in flight.")
}
PeersIterState::Finished => break,
}
}
let mut result = iter
.into_result()
.into_iter()
.map(Key::from)
.collect::<Vec<_>>();
result.sort_unstable_by_key(|a| target.distance(a));
result.into_iter().map(|k| k.into_preimage()).collect()
}
QuickCheck::new()
.tests(10)
.quickcheck(prop as fn(_, _, _, _) -> _)
}
#[test]
fn failure_can_not_overwrite_previous_success() {
let now = Instant::now();
let peer = PeerId::random();
let mut iter = ClosestDisjointPeersIter::new(
Key::from(PeerId::random()).into(),
iter::once(Key::from(peer)),
);
assert!(matches!(iter.next(now), PeersIterState::Waiting(Some(_))));
// Expect peer to be marked as succeeded.
assert!(iter.on_success(&peer, iter::empty()));
assert_eq!(
iter.contacted_peers.get(&peer),
Some(&PeerState {
initiated_by: IteratorIndex(0),
response: ResponseState::Succeeded,
})
);
// Expect peer to stay marked as succeeded.
assert!(!iter.on_failure(&peer));
assert_eq!(
iter.contacted_peers.get(&peer),
Some(&PeerState {
initiated_by: IteratorIndex(0),
response: ResponseState::Succeeded,
})
);
}
}