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Handle timing underflows in attestation service (#952)

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Age Manning 2020-03-24 21:05:22 +11:00 committed by GitHub
parent 2b6da4b8de
commit af1c5c326c
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 40 additions and 24 deletions
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64
beacon_node/network/src/attestation_service/mod.rs
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@ -140,10 +140,14 @@ impl<T: BeaconChainTypes> AttestationService<T> {
% self.beacon_chain.spec.attestation_subnet_count,
);
// determine if we should run a discovery lookup request and request it if required
let _ = self.discover_peers_request(subnet_id, subscription.slot);
if let Err(e) = self.discover_peers_request(subnet_id, subscription.slot) {
warn!(self.log, "Discovery lookup request error"; "error" => e);
}
// set the subscription timer to subscribe to the next subnet if required
let _ = self.subscribe_to_subnet(subnet_id, subscription.slot);
if let Err(e) = self.subscribe_to_subnet(subnet_id, subscription.slot) {
warn!(self.log, "Subscription to subnet error"; "error" => e);
}
}
Ok(())
}
@ -166,10 +170,12 @@ impl<T: BeaconChainTypes> AttestationService<T> {
&mut self,
subnet_id: SubnetId,
subscription_slot: Slot,
) -> Result<(), ()> {
let current_slot = self.beacon_chain.slot_clock.now().ok_or_else(|| {
warn!(self.log, "Could not get the current slot");
})?;
) -> Result<(), &'static str> {
let current_slot = self
.beacon_chain
.slot_clock
.now()
.ok_or_else(|| "Could not get the current slot")?;
let slot_duration = Duration::from_millis(self.beacon_chain.spec.milliseconds_per_slot);
// if there is enough time to perform a discovery lookup
@ -211,9 +217,7 @@ impl<T: BeaconChainTypes> AttestationService<T> {
.beacon_chain
.slot_clock
.duration_to_next_slot()
.ok_or_else(|| {
warn!(self.log, "Unable to determine duration to next slot");
})?;
.ok_or_else(|| "Unable to determine duration to next slot")?;
// The -1 is done here to exclude the current slot duration, as we will use
// `duration_to_next_slot`.
let slots_until_discover = subscription_slot
@ -239,38 +243,50 @@ impl<T: BeaconChainTypes> AttestationService<T> {
&mut self,
subnet_id: SubnetId,
subscription_slot: Slot,
) -> Result<(), ()> {
) -> Result<(), &'static str> {
// initialise timing variables
let current_slot = self.beacon_chain.slot_clock.now().ok_or_else(|| {
warn!(self.log, "Could not get the current slot");
})?;
let current_slot = self
.beacon_chain
.slot_clock
.now()
.ok_or_else(|| "Could not get the current slot")?;
// Ignore a subscription to the current slot.
if current_slot >= subscription_slot {
return Err("Could not subscribe to current slot, insufficient time");
}
let slot_duration = Duration::from_millis(self.beacon_chain.spec.milliseconds_per_slot);
let advance_subscription_duration = slot_duration
.checked_div(ADVANCE_SUBSCRIBE_TIME)
.expect("ADVANCE_SUBSCRIPTION_TIME cannot be too large");
let duration_to_next_slot = self
.beacon_chain
.slot_clock
.duration_to_next_slot()
.ok_or_else(|| "Unable to determine duration to next slot")?;
// calculate the time to subscribe to the subnet
let duration_to_subscribe = {
let duration_to_next_slot = self
.beacon_chain
.slot_clock
.duration_to_next_slot()
.ok_or_else(|| {
warn!(self.log, "Unable to determine duration to next slot");
})?;
// The -1 is done here to exclude the current slot duration, as we will use
// `duration_to_next_slot`.
let slots_until_subscribe = subscription_slot
.saturating_sub(current_slot)
.saturating_sub(1u64);
duration_to_next_slot + slot_duration * (slots_until_subscribe.as_u64() as u32)
- advance_subscription_duration
duration_to_next_slot
.checked_add(slot_duration)
.ok_or_else(|| "Overflow in adding slot_duration attestation time")?
.checked_mul(slots_until_subscribe.as_u64() as u32)
.ok_or_else(|| "Overflow in multiplying number of slots in attestation time")?
.checked_sub(advance_subscription_duration)
.unwrap_or_else(|| Duration::from_secs(0))
};
// the duration until we no longer need this subscription. We assume a single slot is
// sufficient.
let expected_end_subscription_duration =
duration_to_subscribe + slot_duration + advance_subscription_duration;
let expected_end_subscription_duration = duration_to_subscribe
+ slot_duration
+ std::cmp::min(advance_subscription_duration, duration_to_next_slot);
// Checks on current subscriptions
// Note: We may be connected to a long-lived random subnet. In this case we still add the