* Add @description decorator
* Unify test case naming style
* more clean ups
* Altair tests cleanup
* Clean up Altair and Bellatrix `process_deposit` tests
* Clean up Bellatrix tests
* Clean up Capella tests
* PR feedback from @ralexstokes
* Add comments on the deposit fork version tests
* Remove `test_incorrect_sig_other_version` since it is duplicate to `test_ineffective_deposit_with_bad_fork_version`
* Add `test_ineffective_deposit_with_current_fork_version`
Future light client protocol extensions may include data from the block
in addition to data from the state, e.g., `ExecutionPayloadHeader`.
To prepare for this, also pass the block to the corresponding functions.
In practice, blocks access is easier than historic state access, meaning
there are no practical limitations due to this change.
Add more detailed LC object documentation to explain that the various
merkle proofs are relative to the beacon block's state root.
Likewise, clarify that sync committees relate to the finalized header
(not to the optimistic header, which can be a period ahead).
For LC gossip, the documentation did not specify what slot number to use
for deriving the gossip objects. This missing documentation is now added
to document using `attested_header.slot`.
While the current Altair specs define structures to aid light client
development, one missing key aspect is the network protocol definition.
Certain implementations have started defining their own REST based APIs,
e.g., Lodestar at https://github.com/ChainSafe/lodestar/blob/master/packages/api/src/routes/lightclient.ts
While such APIs are useful, REST does not seem to be the ideomatic
choice as the sole API available at such a low level for Ethereum.
This patch introduces a libp2p based protocol to allow light clients to
sync to the latest `BeaconBlockHeader` in a trustless and decentralized
manner, building on top of prior work from:
- @hwwhww at https://github.com/ethereum/consensus-specs/pull/2267
- @jinfwhuang at https://github.com/ethereum/consensus-specs/pull/2786
- Lodestar's REST API (also has an endpoint to fetch merkle proofs!)
Replaces `process_slot_for_light_client_store` which force updates the
`LightClientStore` automatically based on `finalized_header` age with
`try_light_client_store_force_update` which may be manually called based
on use case dependent heuristics if light client sync appears stuck.
Not all use cases share the same risk profile.
Introduces reduced `LightClientUpdate` structures to allow keeping track
of the latest `finalized_header` and `optimistic_header`. This may also
help in scheduling the next query for a full `LightClientUpdate` once
sync committee finality has been reached.
Adds `create_light_client_bootstrap` and `create_light_client_update`
functions as a reference implementation for serving light client data.
This also enables a new test harness to verify that light client data
gets applied to a `LightClientStore` as expected.
Introduces a new `LightClientBootstrap` structure to allow setting up a
`LightClientStore` with the initial sync committee and block header from
a user-configured trusted block root.
This leads to new cases where the `LightClientStore` is only aware of
the current but not the next sync committee. As a side effect of these
new cases, the store's `finalized_header` may now advance into the next
sync committee period before a corresponding `LightClientUpdate` with
the new sync committee is obtained, improving responsiveness.
Note that so far, `LightClientUpdate.attested_header.slot` needed to be
newer than `LightClientStore.finalized_header.slot`. However, it is now
necessary to also consider certain older updates to try and backfill the
`next_sync_committee`. The `is_better_update` helper is also updated to
improve `best_valid_update` tracking.
`LightClientUpdate` structures currently use different merkle proof root
depending on the presence of `finalized_header`. By always rooting it in
the same state (the `attested_header.state_root`), logic gets simpler.
Caveats:
- In periods of extended non-finality, `update.finalized_header` may now
be outdated by several sync committee periods. The old implementation
rejected such updates as the `next_sync_committee` in them was stale,
but the new implementation can properly handle this case.
- The `next_sync_committee` can no longer be considered finalized based
on `is_finality_update`. Instead, waiting until `finalized_header` is
in the `attested_header`'s sync committee period is now necessary.
- Because `update.finalized_header > store.finalized_header` no longer
holds (for updates with finality), an `is_better_update` helper is
added to improve `best_valid_update` tracking (in the past, finalized
updates with supermajority participation would always directly apply)
This PR builds on prior work from:
- @hwwhww at https://github.com/ethereum/consensus-specs/pull/2829
The producer of `LightClientUpdate` structures usually does not know how
far the `LightClientStore` on the client side has advanced. Updates are
currently rejected when including a redundant `next_sync_committee` not
advancing the `LightClientStore`. Behaviour is changed to allow this.
When `state.finalized_checkpoint` references the genesis slot, it points
to an empty `root`, instead of the actual genesis block hash. This patch
updates the `LightClientUpdate` logic to allow including finality proofs
for genesis `finalized_checkpoint.root`, better supporting non-mainnet.
When including such a finality proof, the proof is for the empty `root`,
but `finalized_header` is kept zeroed out to signify this edge case.
The `fork_version` field in `LightClientUpdate` can be derived from the
`update.signature_slot` value by consulting the locally configured fork
schedule. The light client already needs access to the fork schedule to
determine the `GeneralizedIndex` values used for merkle proofs, and the
memory layouts of the structures (including `LightClientUpdate`). The
`fork_version` itself is network dependent and doesn't reveal that info.
Hsiao-Wei Wang
Etan Kissling
Michael Sproul
Michael Sproul
Alex Stokes
Lion - dapplion
Ben Guidarelli