## 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
## Description
This PR wraps the stdlib sync.(RW)Mutex & godeadlock.(RW)Mutex. This enables using go-deadlock via a build flag instead of using sed to replace sync with godeadlock in all files
Closes: #3242
Closes#4603
Commands used (VIM):
```
:args `rg -l errors.Wrap`
:argdo normal @q | update
```
where q is a macros rewriting the `errors.Wrap` to `fmt.Errorf`.
Closes: #4537
Uses SignedHeaderBefore to find header before unverified header and then bisection to verify the header. Only when header is between first and last trusted header height else if before the first trusted header height then regular backwards verification is used.
closes#4469
Improved speed of cleanup by using SignedHeaderAfter instead of TrustedHeader to jump from header to header.
Prune() is now called when a new header and validator set are saved and is a function dealt by the database itself
## Commits:
* prune headers and vals
* modified cleanup and tests
* fixes after my own review
* implement Prune func
* make db ops concurrently safe
* use Iterator in SignedHeaderAfter
we should iterate from height+1, not from the end!
* simplify cleanup
Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>
Before we were storing trustedHeader (height=1) and trustedNextVals
(height=2).
After this change, we will be storing trustedHeader (height=1) and
trustedVals (height=1). This a) simplifies the code b) fixes#4399
inconsistent pairing issue c) gives a relayer access to the current
validator set #4470.
The only downside is more jumps during bisection. If validator set
changes between trustedHeader and the next header (by 2/3 or more), the
light client will be forced to download the next header and check that
2/3+ signed the transition. But we don't expect validator set change too
much and too often, so it's an acceptable compromise.
Closes#4470 and #4399
Closes#4328
When TrustedHeader(height) is called, if the height is less than the trusted height but the header is not in the trusted store then a function finds the previous lowest height with a trusted header and performs a forwards sequential verification to the header of the height that was given. If no error is found it updates the trusted store with the header and validator set for that height and can then return them to the user.
Commits:
* drafted trusted header
* created function to find previous trusted height
* updates missing headers less than the trusted height
* minor cosmetic tweaks
* incorporated suggestions
* lite2: implement Backwards verification
and add SignedHeaderAfter func to Store interface
Refs https://github.com/tendermint/tendermint/issues/4328#issuecomment-581878549
* remove unused method
* write tests
* start with next height in SignedHeaderAfter func
* fix linter errors
* address Callum's comments
Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>
* 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
* dep: update tm-db to 0.4.0
- update 0.4.0 as it is a breaking change and cannot be handled by depndabot
Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>
* more work towards error handling
* error and emtpy bytes handling
* work on tests
* add changelog entry, change some error handling
* address some pr comments
* panic in a few more places
* move error higher up
* redo some error handling
* fix some bz == nil to len(bz) == 0
* change statebytes
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
Marko
Erik Grinaker
Anton Kaliaev