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nimbus-eth2/beacon_chain/gossip_processing
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Jacek Sieka 0a4728a241
Handle access to historical data for which there is no state (#3217) 
With checkpoint sync in particular, and state pruning in the future,
loading states or state-dependent data may fail. This PR adjusts the
code to allow this to be handled gracefully.

In particular, the new availability assumption is that states are always
available for the finalized checkpoint and newer, but may fail for
anything older.

The `tail` remains the point where state loading de-facto fails, meaning
that between the tail and the finalized checkpoint, we can still get
historical data (but code should be prepared to handle this as an
error).

However, to harden the code against long replays, several operations
which are assumed to work only with non-final data (such as gossip
verification and validator duties) now limit their search horizon to
post-finalized data.

* harden several state-dependent operations by logging an error instead
of introducing a panic when state loading fails
* `withState` -> `withUpdatedState` to differentiate from the other
`withState`
* `updateStateData` can now fail if no state is found in database - it
is also hardened against excessively long replays
* `getEpochRef` can now fail when replay fails
* reject blocks with invalid target root - they would be ignored
previously
* fix recursion bug in `isProposed`
2022-01-05 19:38:04 +01:00
..
batch_validation.nim
Lazy aggregated batch verification (#3212)
2021-12-29 15:28:40 +01:00
block_processor.nim
use BeaconTime instead of Slot in fork choice (#3138)
2021-12-21 18:56:08 +00:00
consensus_manager.nim
use BeaconTime instead of Slot in fork choice (#3138)
2021-12-21 18:56:08 +00:00
eth2_processor.nim
Handle access to historical data for which there is no state (#3217)
2022-01-05 19:38:04 +01:00
gossip_validation.nim
Handle access to historical data for which there is no state (#3217)
2022-01-05 19:38:04 +01:00
README.md
update from phase0/altair v1.1.6 URLs to v1.1.8 spec URLs (#3238)
2022-01-04 03:57:15 +00:00

README.md

Gossip Processing

This folder holds a collection of modules to:

  • validate raw gossip data before
    • rebroadcasting it (potentially aggregated)
    • sending it to one of the consensus object pools

Validation

Gossip validation is different from consensus verification in particular for blocks.

There are multiple consumers of validated consensus objects:

  • a ValidationResult.Accept output triggers rebroadcasting in libp2p
    • We jump into method validate(PubSub, Message) in libp2p/protocols/pubsub/pubsub.nim
    • which was called by rpcHandler(GossipSub, PubSubPeer, RPCMsg)
  • a blockValidator message enqueues the validated object to the processing queue in block_processor
    • blockQueue: AsyncQueue[BlockEntry] (shared with request_manager and sync_manager)
    • This queue is then regularly processed to be made available to the consensus object pools.
  • a xyzValidator message adds the validated object to a pool in eth2_processor
    • Attestations (unaggregated and aggregated) get collected into batches.
    • Once a threshold is exceeded or after a timeout, they get validated together using BatchCrypto.

Security concerns

As the first line of defense in Nimbus, modules must be able to handle bursts of data that may come:

  • from malicious nodes trying to DOS us
  • from long periods of non-finality, creating lots of forks, attestations