## Description
I'm just doing a self audit of the light client. There's a few things I've changed
- Validate trust level in `VerifyNonAdjacent` function
- Make errNoWitnesses public (it's something people running software on top of a light client should be able to parse)
- Remove `ChainID` check of witnesses on start up. We do this already when we compare the first header with witnesses
- Remove `ChainID()` from provider interface
Closes: #4538
Fixes#4739, kind of. See #4740 for the proper fix.
---
For contributor use:
- [x] Wrote tests
- [x] Updated CHANGELOG_PENDING.md
- [x] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [x] Updated relevant documentation (`docs/`) and code comments
- [x] Re-reviewed `Files changed` in the Github PR explorer
- [x] Applied Appropriate Labels
Closes: #4530
This PR contains logic for both submitting an evidence by the light client (lite2 package) and receiving it on the Tendermint side (/broadcast_evidence RPC and/or EvidenceReactor#Receive). Upon receiving the ConflictingHeadersEvidence (introduced by this PR), the Tendermint validates it, then breaks it down into smaller pieces (DuplicateVoteEvidence, LunaticValidatorEvidence, PhantomValidatorEvidence, PotentialAmnesiaEvidence). Afterwards, each piece of evidence is verified against the state of the full node and added to the pool, from which it's reaped upon block creation.
* rpc/client: do not pass height param if height ptr is nil
* rpc/core: validate incoming evidence!
* only accept ConflictingHeadersEvidence if one
of the headers is committed from this full node's perspective
This simplifies the code. Plus, if there are multiple forks, we'll
likely to receive multiple ConflictingHeadersEvidence anyway.
* swap CommitSig with Vote in LunaticValidatorEvidence
Vote is needed to validate signature
* no need to embed client
http is a provider and should not be used as a client
Closes#4385
* extract TrustOptions into its own file
* print trusted hash before asking whenever to rollback or not
so the user could reset the light client with the trusted header
* do not return an error if rollback is aborted
reason: we trust the old header presumably, so can continue from it.
* add note about time of initial header
* improve logging and add comments
* cross-check newHeader after LC verified it
* check if header is not nil
so we don't crash on the next line
* remove witness if it sends us incorrect header
* require at least one witness
* fix build and tests
* rename tests and assert for specific error
* wrote a test
* fix linter errors
* only check 1/3 if headers diverge
* lite2: move AutoClient into Client
Most of the users will want auto update feature, so it makes sense to
move it into the Client itself, rather than having a separate
abstraction (it makes the code cleaner, but introduces an extra thing
the user will need to learn).
Also, add `FirstTrustedHeight` func to Client to get first trusted height.
* fix db store tests
* separate examples for auto and manual clients
* AutoUpdate tries to update to latest state
NOT 1 header at a time
* fix errors
* lite2: make Logger an option
remove SetLogger func
* fix lite cmd
* lite2: make concurrency assumptions explicit
* fixes after my own review
* no need for nextHeightFn
sequence func will download intermediate headers
* correct comment
Refs #1771
ADR: https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-044-lite-client-with-weak-subjectivity.md
## Commits:
* add Verifier and VerifyCommitTrusting
* add two more checks
make trustLevel an option
* float32 for trustLevel
* check newHeader time
* started writing lite Client
* unify Verify methods
* ensure h2.Header.bfttime < h1.Header.bfttime + tp
* move trust checks into Verify function
* add more comments
* more docs
* started writing tests
* unbonding period failures
* tests are green
* export ErrNewHeaderTooFarIntoFuture
* make golangci happy
* test for non-adjusted headers
* more precision
* providers and stores
* VerifyHeader and VerifyHeaderAtHeight funcs
* fix compile errors
* remove lastVerifiedHeight, persist new trusted header
* sequential verification
* remove TrustedStore option
* started writing tests for light client
* cover basic cases for linear verification
* bisection tests PASS
* rename BisectingVerification to SkippingVerification
* refactor the code
* add TrustedHeader method
* consolidate sequential verification tests
* consolidate skipping verification tests
* rename trustedVals to trustedNextVals
* start writing docs
* ValidateTrustLevel func and ErrOldHeaderExpired error
* AutoClient and example tests
* fix errors
* update doc
* remove ErrNewHeaderTooFarIntoFuture
This check is unnecessary given existing a) ErrOldHeaderExpired b)
h2.Time > now checks.
* return an error if we're at more recent height
* add comments
* add LastSignedHeaderHeight method to Store
I think it's fine if Store tracks last height
* copy over proxy from old lite package
* make TrustedHeader return latest if height=0
* modify LastSignedHeaderHeight to return an error if no headers exist
* copy over proxy impl
* refactor proxy and start http lite client
* Tx and BlockchainInfo methods
* Block method
* commit method
* code compiles again
* lite client compiles
* extract updateLiteClientIfNeededTo func
* move final parts
* add placeholder for tests
* force usage of lite http client in proxy
* comment out query tests for now
* explicitly mention tp: trusting period
* verify nextVals in VerifyHeader
* refactor bisection
* move the NextValidatorsHash check into updateTrustedHeaderAndVals
+ update the comment
* add ConsensusParams method to RPC client
* add ConsensusParams to rpc/mock/client
* change trustLevel type to a new cmn.Fraction type
+ update SkippingVerification comment
* stress out trustLevel is only used for non-adjusted headers
* fixes after Fede's review
Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>
* compare newHeader with a header from an alternative provider
* save pivot header
Refs https://github.com/tendermint/tendermint/pull/3989#discussion_r349122824
* check header can still be trusted in TrustedHeader
Refs https://github.com/tendermint/tendermint/pull/3989#discussion_r349101424
* lite: update Validators and Block endpoints
- Block no longer contains BlockMeta
- Validators now accept two additional params: page and perPage
* make linter happy
Callum Waters
Anton Kaliaev
Marko
Erik Grinaker
Alexander Bezobchuk
Peter Mrekaj