Don't return errors on HTTP API for already-known messages (#3341)

## Issue Addressed

- Resolves #3266

## Proposed Changes

Return 200 OK rather than an error when a block, attestation or sync message is already known.

Presently, we will log return an error which causes a BN to go "offline" from the VCs perspective which causes the fallback mechanism to do work to try and avoid and upcheck offline nodes. This can be observed as instability in the `vc_beacon_nodes_available_count` metric.

The current behaviour also causes scary logs for the user. There's nothing to *actually* be concerned about when we see duplicate messages, this can happen on fallback systems (see code comments).

## Additional Info

NA
This commit is contained in:
Paul Hauner 2022-08-10 07:52:57 +00:00
parent 052d5cf31f
commit 2de26b20f8
3 changed files with 105 additions and 3 deletions

View File

@ -1168,12 +1168,46 @@ pub fn serve<T: BeaconChainTypes>(
blocking_json_task(move || {
let seen_timestamp = timestamp_now();
let mut failures = Vec::new();
let mut num_already_known = 0;
for (index, attestation) in attestations.as_slice().iter().enumerate() {
let attestation = match chain
.verify_unaggregated_attestation_for_gossip(attestation, None)
{
Ok(attestation) => attestation,
Err(AttnError::PriorAttestationKnown { .. }) => {
num_already_known += 1;
// Skip to the next attestation since an attestation for this
// validator is already known in this epoch.
//
// There's little value for the network in validating a second
// attestation for another validator since it is either:
//
// 1. A duplicate.
// 2. Slashable.
// 3. Invalid.
//
// We are likely to get duplicates in the case where a VC is using
// fallback BNs. If the first BN actually publishes some/all of a
// batch of attestations but fails to respond in a timely fashion,
// the VC is likely to try publishing the attestations on another
// BN. That second BN may have already seen the attestations from
// the first BN and therefore indicate that the attestations are
// "already seen". An attestation that has already been seen has
// been published on the network so there's no actual error from
// the perspective of the user.
//
// It's better to prevent slashable attestations from ever
// appearing on the network than trying to slash validators,
// especially those validators connected to the local API.
//
// There might be *some* value in determining that this attestation
// is invalid, but since a valid attestation already it exists it
// appears that this validator is capable of producing valid
// attestations and there's no immediate cause for concern.
continue;
}
Err(e) => {
error!(log,
"Failure verifying attestation for gossip";
@ -1240,6 +1274,15 @@ pub fn serve<T: BeaconChainTypes>(
));
}
}
if num_already_known > 0 {
debug!(
log,
"Some unagg attestations already known";
"count" => num_already_known
);
}
if failures.is_empty() {
Ok(())
} else {
@ -2234,6 +2277,16 @@ pub fn serve<T: BeaconChainTypes>(
// identical aggregates, especially if they're using the same beacon
// node.
Err(AttnError::AttestationAlreadyKnown(_)) => continue,
// If we've already seen this aggregator produce an aggregate, just
// skip this one.
//
// We're likely to see this with VCs that use fallback BNs. The first
// BN might time-out *after* publishing the aggregate and then the
// second BN will indicate it's already seen the aggregate.
//
// There's no actual error for the user or the network since the
// aggregate has been successfully published by some other node.
Err(AttnError::AggregatorAlreadyKnown(_)) => continue,
Err(e) => {
error!(log,
"Failure verifying aggregate and proofs";

View File

@ -1,9 +1,9 @@
use crate::metrics;
use beacon_chain::validator_monitor::{get_block_delay_ms, timestamp_now};
use beacon_chain::{BeaconChain, BeaconChainTypes, CountUnrealized};
use beacon_chain::{BeaconChain, BeaconChainTypes, BlockError, CountUnrealized};
use lighthouse_network::PubsubMessage;
use network::NetworkMessage;
use slog::{crit, error, info, Logger};
use slog::{crit, error, info, warn, Logger};
use slot_clock::SlotClock;
use std::sync::Arc;
use tokio::sync::mpsc::UnboundedSender;
@ -86,6 +86,27 @@ pub async fn publish_block<T: BeaconChainTypes>(
Ok(())
}
Err(BlockError::BlockIsAlreadyKnown) => {
info!(
log,
"Block from HTTP API already known";
"block" => ?block.canonical_root(),
"slot" => block.slot(),
);
Ok(())
}
Err(BlockError::RepeatProposal { proposer, slot }) => {
warn!(
log,
"Block ignored due to repeat proposal";
"msg" => "this can happen when a VC uses fallback BNs. \
whilst this is not necessarily an error, it can indicate issues with a BN \
or between the VC and BN.",
"slot" => slot,
"proposer" => proposer,
);
Ok(())
}
Err(e) => {
let msg = format!("{:?}", e);
error!(

View File

@ -11,7 +11,7 @@ use beacon_chain::{
use eth2::types::{self as api_types};
use lighthouse_network::PubsubMessage;
use network::NetworkMessage;
use slog::{error, warn, Logger};
use slog::{debug, error, warn, Logger};
use slot_clock::SlotClock;
use std::cmp::max;
use std::collections::HashMap;
@ -189,6 +189,24 @@ pub fn process_sync_committee_signatures<T: BeaconChainTypes>(
verified_for_pool = Some(verified);
}
// If this validator has already published a sync message, just ignore this message
// without returning an error.
//
// This is likely to happen when a VC uses fallback BNs. If the first BN publishes
// the message and then fails to respond in a timely fashion then the VC will move
// to the second BN. The BN will then report that this message has already been
// seen, which is not actually an error as far as the network or user are concerned.
Err(SyncVerificationError::PriorSyncCommitteeMessageKnown {
validator_index,
slot,
}) => {
debug!(
log,
"Ignoring already-known sync message";
"slot" => slot,
"validator_index" => validator_index,
);
}
Err(e) => {
error!(
log,
@ -283,6 +301,16 @@ pub fn process_signed_contribution_and_proofs<T: BeaconChainTypes>(
// If we already know the contribution, don't broadcast it or attempt to
// further verify it. Return success.
Err(SyncVerificationError::SyncContributionAlreadyKnown(_)) => continue,
// If we've already seen this aggregator produce an aggregate, just
// skip this one.
//
// We're likely to see this with VCs that use fallback BNs. The first
// BN might time-out *after* publishing the aggregate and then the
// second BN will indicate it's already seen the aggregate.
//
// There's no actual error for the user or the network since the
// aggregate has been successfully published by some other node.
Err(SyncVerificationError::AggregatorAlreadyKnown(_)) => continue,
Err(e) => {
error!(
log,