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More polish and fixes

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Justin 2020-11-17 15:30:09 +00:00 committed by GitHub
parent 7ffc9c5bc0
commit 5e717a456d
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1 changed files with 11 additions and 8 deletions
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19
specs/lightclient/sync-protocol.md
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@ -43,6 +43,7 @@ This document suggests a minimal light client design for the beacon chain that u
| Name | Value |
| - | - |
| `MIN_SYNC_COMMITTEE_PARTICIPANTS` | `1` |
| `MAX_VALID_LIGHT_CLIENT_UPDATES` | `uint64(2**64 - 1)` |
### Time parameters
@ -75,7 +76,7 @@ class LightClientUpdate(Container):
# Sync committee aggregate signature
sync_committee_bits: Bitlist[MAX_SYNC_COMMITTEE_SIZE]
sync_committee_signature: BLSSignature
# Fork version corresponding to the aggregate signature
# Fork version for the aggregate signature
fork_version
```
@ -122,6 +123,7 @@ def is_valid_light_client_update(store: LightClientStore, update: LightClientUpd
# Verify sync committee bitfield length
sync_committee = new_snapshot.current_sync_committee
assert len(update.sync_committee_bits) == len(sync_committee)
assert sum(update.sync_committee_bits) > MIN_SYNC_COMMITTEE_PARTICIPANTS
# Verify sync committee aggregate signature
participant_pubkeys = [pubkey for (bit, pubkey) in zip(update.sync_committee_bits, sync_committee.pubkeys) if bit]
@ -136,15 +138,16 @@ def is_valid_light_client_update(store: LightClientStore, update: LightClientUpd
```python
def process_light_client_update(store: LightClientStore, update: LightClientUpdate, current_slot: Slot) -> None:
# Validate update
assert is_valid_light_client_update(store, update)
valid_updates.append(update)
if sum(update.sync_committee_bits) * 3 > len(update.sync_committee_bits) * 2:
# Immediate update when quorum is reached
store.snapshot = update.snapshot
valid_updates = []
else:
valid_updates.append(update)
# Force an update after the update timeout has elapsed
if current_slot > old_snapshot.header.slot + LIGHT_CLIENT_UPDATE_TIMEOUT:
best_update = max(valid_updates, key=lambda update: sum(update.sync_committee_bits))
store.snapshot = best_update.new_snapshot
elif current_slot > old_snapshot.header.slot + LIGHT_CLIENT_UPDATE_TIMEOUT:
# Forced best update when the update timeout has elapsed
store.snapshot = max(valid_updates, key=lambda update: sum(update.sync_committee_bits)).new_snapshot
valid_updates = []
```