-
Notifications
You must be signed in to change notification settings - Fork 95
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
implement HeaderOracle and get SPV functions to use that
Change-Id: Ie1996cf9f50c73f16a4e5a1fa30aea67e648d188 remove redundant prett-show dependency Change-Id: I2a4e0ca1a615c0edf28576ee763af6b16aebc234
- Loading branch information
Showing
6 changed files
with
202 additions
and
276 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,124 @@ | ||
| {-# language | ||
| DerivingStrategies | ||
| , ImportQualifiedPost | ||
| , LambdaCase | ||
| , OverloadedRecordDot | ||
| , RecordWildCards | ||
| , ScopedTypeVariables | ||
| , TypeApplications | ||
| #-} | ||
|
|
||
| module Chainweb.BlockHeaderDB.HeaderOracle | ||
| ( | ||
| -- * Oracle type | ||
| HeaderOracle | ||
| -- ** Accessors | ||
| , lowerBound | ||
| , upperBound | ||
|
|
||
| -- * Oracle creation | ||
| , create | ||
| , createSpv | ||
| -- ** Oracle creation Exceptions | ||
| , InvalidHeaderOracleBounds(..) | ||
|
|
||
| -- * Oracle querying | ||
| , query | ||
| , HeaderOracleResponse(..) | ||
| ) | ||
| where | ||
|
|
||
| import Chainweb.BlockHash (BlockHash) | ||
| import Chainweb.BlockHeader (BlockHeader, blockHash, blockHeight, genesisBlockHeader) | ||
| import Chainweb.BlockHeaderDB (BlockHeaderDb) | ||
| import Chainweb.TreeDB (seekAncestor) | ||
| import Chainweb.TreeDB qualified as TreeDB | ||
| import Chainweb.Version (_chainwebVersion) | ||
| import Chainweb.Version.Guards (spvProofExpirationWindow) | ||
| import Control.Exception (Exception(..), throwIO) | ||
| import Control.Lens (view) | ||
| import Numeric.Natural (Natural) | ||
|
|
||
| -- | A 'HeaderOracle' is a 'BlockHeaderDb' with a lower and upper bound, and the only | ||
| -- query on it is whether a given block is within those bounds. | ||
| data HeaderOracle = HeaderOracle | ||
| { lowerBound :: !BlockHeader | ||
| , upperBound :: !BlockHeader | ||
| , db :: !BlockHeaderDb | ||
| } | ||
|
|
||
| -- | Create a new 'HeaderOracle' specifically for SPV verification, with the given upper bound. | ||
| -- | ||
| -- The lower bound of the oracle is determined by the 'spvProofExpirationWindow'. | ||
| createSpv :: BlockHeaderDb -> BlockHeader -> IO HeaderOracle | ||
| createSpv db upperBound = do | ||
| let mWindow = spvProofExpirationWindow (_chainwebVersion upperBound) (view blockHeight upperBound) | ||
| let gh = genesisBlockHeader (_chainwebVersion upperBound) upperBound | ||
| let defaultOracle = create db gh upperBound | ||
|
|
||
| case mWindow of | ||
| Nothing -> do | ||
| defaultOracle | ||
| Just window -> do | ||
| mWindowthAncestor <- do | ||
| let w = fromIntegral @_ @Natural window | ||
| let ur = TreeDB.rank upperBound | ||
| let gr = TreeDB.rank gh | ||
| -- Saturated subtraction with the genesis rank as origin | ||
| if w + gr <= ur | ||
| then do | ||
| seekAncestor db upperBound (ur - w) | ||
| else do | ||
| return Nothing | ||
| case mWindowthAncestor of | ||
| Nothing -> do | ||
| defaultOracle | ||
| Just windowthAncestor -> do | ||
| create db windowthAncestor upperBound | ||
|
|
||
| -- | Exception thrown when creating a new 'HeaderOracle' with invalid bounds. | ||
| data InvalidHeaderOracleBounds = InvalidHeaderOracleBounds !BlockHash !BlockHash | ||
| deriving stock (Eq, Show) | ||
|
|
||
| instance Exception InvalidHeaderOracleBounds where | ||
| displayException (InvalidHeaderOracleBounds l u) = "Header Oracle `create` called with a (lower, upper) pair, where `lower` is not an ancestor of `upper`: " ++ show (l, u) | ||
|
|
||
| -- | Create a new 'HeaderOracle' with the given lower and upper bounds. | ||
| -- | ||
| -- Throws an 'InvalidHeaderOracleBounds' exception if the lower bound is not an ancestor of the upper bound. | ||
| create :: BlockHeaderDb -> BlockHeader -> BlockHeader -> IO HeaderOracle | ||
| create db lowerBound upperBound = do | ||
| valid <- TreeDB.ancestorOf db (view blockHash lowerBound) (view blockHash upperBound) | ||
| if valid | ||
| then do | ||
| return HeaderOracle | ||
| { .. | ||
| } | ||
| else do | ||
| throwIO $ InvalidHeaderOracleBounds (view blockHash lowerBound) (view blockHash upperBound) | ||
|
|
||
| -- TODO: add note about we can't have two different errors here, because shallow nodes can't determine which one is the case | ||
| -- eg we cant have data Response = TooLate | OutOfBounds | Success | ||
|
|
||
| -- | The response from the oracle when querying a block. | ||
| data HeaderOracleResponse | ||
| = OutOfBounds | ||
| -- ^ The block is not within the oracle's bounds. | ||
| | InBounds | ||
| -- ^ The block is within the oracle's bounds. | ||
| deriving stock (Eq) | ||
|
|
||
| -- | Query the oracle, asking if the block is within its bounds. | ||
| query :: () | ||
| => HeaderOracle | ||
| -> BlockHash | ||
| -> IO HeaderOracleResponse | ||
| query oracle subject = do | ||
| -- Check if the lower bound is an ancestor of the header | ||
| -- Check if the header is an ancestor of the upper bound | ||
| r <- (&&) | ||
| <$> TreeDB.ancestorOf oracle.db (view blockHash oracle.lowerBound) subject | ||
| <*> TreeDB.ancestorOf oracle.db subject (view blockHash oracle.upperBound) | ||
| return $ if r | ||
| then InBounds | ||
| else OutOfBounds |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.