216 lines
7.8 KiB
Nim
216 lines
7.8 KiB
Nim
# Nimbus
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# Copyright (c) 2022 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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{.push raises: [Defect].}
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import
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eth/rlp, eth/common/eth_types_rlp,
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ssz_serialization, ssz_serialization/[proofs, merkleization],
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../../common/common_types,
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./history_content
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export ssz_serialization, merkleization, proofs, eth_types_rlp
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# Header Accumulator, as per specification:
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# https://github.com/ethereum/portal-network-specs/blob/master/history-network.md#the-header-accumulator
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# But with the adjustment to finish the accumulator at merge point.
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const
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epochSize* = 8192 # blocks
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# Allow this to be adjusted at compile time for testing. If more constants
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# need to be adjusted we can add some presets file.
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mergeBlockNumber* {.intdefine.}: uint64 = 15537394
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# Note: This is like a ceil(mergeBlockNumber / epochSize)
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# Could use ceilDiv(mergeBlockNumber, epochSize) in future versions
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preMergeEpochs* = (mergeBlockNumber + epochSize - 1) div epochSize
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# TODO:
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# Currently disabled, because issue when testing with other
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# `mergeBlockNumber`, but it could be used as value to double check on at
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# merge block.
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# TODO: Could also be used as value to actual finish the accumulator, instead
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# of `mergeBlockNumber`, but:
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# - Still need to store the actual `mergeBlockNumber` and run-time somewhere
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# as it allows for each pre vs post merge block header checking.
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# - Can't limit `historicalEpochs` SSZ list at `preMergeEpochs` value.
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# - Should probably be stated in the portal network specs.
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# TERMINAL_TOTAL_DIFFICULTY = u256"58750000000000000000000"
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type
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HeaderRecord* = object
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blockHash*: BlockHash
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totalDifficulty*: UInt256
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EpochAccumulator* = List[HeaderRecord, epochSize]
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# In the core code of Fluffy the `EpochAccumulator` type is solely used, as
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# `hash_tree_root` is done either once or never on this object after
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# serialization.
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# However for the generation of the proofs for all the headers in an epoch, it
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# needs to be run many times and the cached version of the SSZ list is
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# obviously much faster, so this second type is added for this usage.
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EpochAccumulatorCached* = HashList[HeaderRecord, epochSize]
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Accumulator* = object
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historicalEpochs*: List[Bytes32, int(preMergeEpochs)]
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currentEpoch*: EpochAccumulator
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FinishedAccumulator* = object
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historicalEpochs*: List[Bytes32, int(preMergeEpochs)]
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BlockEpochData* = object
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epochHash*: Bytes32
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blockRelativeIndex*: uint64
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func init*(T: type Accumulator): T =
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Accumulator(
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historicalEpochs: List[Bytes32, int(preMergeEpochs)].init(@[]),
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currentEpoch: EpochAccumulator.init(@[])
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)
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func updateAccumulator*(
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a: var Accumulator, header: BlockHeader) =
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doAssert(header.blockNumber.truncate(uint64) < mergeBlockNumber,
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"No post merge blocks for header accumulator")
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let lastTotalDifficulty =
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if a.currentEpoch.len() == 0:
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0.stuint(256)
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else:
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a.currentEpoch[^1].totalDifficulty
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# TODO: It is a bit annoying to require an extra header + update call to
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# finish an epoch. However, if we were to move this after adding the
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# `HeaderRecord`, there would be no way to get the current total difficulty,
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# unless another field is introduced in the `Accumulator` object.
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if a.currentEpoch.len() == epochSize:
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let epochHash = hash_tree_root(a.currentEpoch)
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doAssert(a.historicalEpochs.add(epochHash.data))
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a.currentEpoch = EpochAccumulator.init(@[])
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let headerRecord =
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HeaderRecord(
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blockHash: header.blockHash(),
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totalDifficulty: lastTotalDifficulty + header.difficulty)
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let res = a.currentEpoch.add(headerRecord)
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doAssert(res, "Can't fail because of currentEpoch length check")
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func finishAccumulator*(a: var Accumulator): FinishedAccumulator =
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# doAssert(a.currentEpoch[^2].totalDifficulty < TERMINAL_TOTAL_DIFFICULTY)
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# doAssert(a.currentEpoch[^1].totalDifficulty >= TERMINAL_TOTAL_DIFFICULTY)
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let epochHash = hash_tree_root(a.currentEpoch)
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doAssert(a.historicalEpochs.add(epochHash.data))
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FinishedAccumulator(historicalEpochs: a.historicalEpochs)
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## Calls and helper calls for building header proofs and verifying headers
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## against the Accumulator and the header proofs.
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func getEpochIndex*(blockNumber: uint64): uint64 =
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blockNumber div epochSize
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func getEpochIndex*(header: BlockHeader): uint64 =
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let blockNumber = header.blockNumber.truncate(uint64)
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## Get the index for the historical epochs
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getEpochIndex(blockNumber)
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func getHeaderRecordIndex(blockNumber: uint64, epochIndex: uint64): uint64 =
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## Get the relative header index for the epoch accumulator
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uint64(blockNumber - epochIndex * epochSize)
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func getHeaderRecordIndex*(header: BlockHeader, epochIndex: uint64): uint64 =
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## Get the relative header index for the epoch accumulator
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getHeaderRecordIndex(header.blockNumber.truncate(uint64), epochIndex)
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func isPreMerge*(blockNumber: uint64): bool =
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blockNumber < mergeBlockNumber
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func isPreMerge*(header: BlockHeader): bool =
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isPreMerge(header.blockNumber.truncate(uint64))
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func verifyProof(
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a: FinishedAccumulator, header: BlockHeader, proof: openArray[Digest]): bool =
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let
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epochIndex = getEpochIndex(header)
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epochAccumulatorHash = Digest(data: a.historicalEpochs[epochIndex])
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leave = hash_tree_root(header.blockHash())
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headerRecordIndex = getHeaderRecordIndex(header, epochIndex)
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# TODO: Implement more generalized `get_generalized_index`
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gIndex = GeneralizedIndex(epochSize*2*2 + (headerRecordIndex*2))
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verify_merkle_multiproof(@[leave], proof, @[gIndex], epochAccumulatorHash)
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func verifyAccumulatorProof*(
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a: FinishedAccumulator, header: BlockHeader, proof: AccumulatorProof):
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Result[void, string] =
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if header.isPreMerge():
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# Note: The proof is typed with correct depth, so no check on this is
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# required here.
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if a.verifyProof(header, proof):
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ok()
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else:
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err("Proof verification failed")
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else:
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err("Cannot verify post merge header with accumulator proof")
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func verifyHeader*(
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a: FinishedAccumulator, header: BlockHeader, proof: BlockHeaderProof):
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Result[void, string] =
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case proof.proofType:
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of BlockHeaderProofType.accumulatorProof:
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a.verifyAccumulatorProof(header, proof.accumulatorProof)
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of BlockHeaderProofType.none:
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err("cannot verify header without proof")
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func buildProof*(
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header: BlockHeader,
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epochAccumulator: EpochAccumulator | EpochAccumulatorCached):
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Result[AccumulatorProof, string] =
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doAssert(header.isPreMerge(), "Must be pre merge header")
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let
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epochIndex = getEpochIndex(header)
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headerRecordIndex = getHeaderRecordIndex(header, epochIndex)
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# TODO: Implement more generalized `get_generalized_index`
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gIndex = GeneralizedIndex(epochSize*2*2 + (headerRecordIndex*2))
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var proof: AccumulatorProof
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? epochAccumulator.build_proof(gIndex, proof)
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ok(proof)
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func buildHeaderWithProof*(
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header: BlockHeader,
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epochAccumulator: EpochAccumulator | EpochAccumulatorCached):
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Result[BlockHeaderWithProof, string] =
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let proof = ? buildProof(header, epochAccumulator)
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ok(BlockHeaderWithProof(
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header: ByteList.init(rlp.encode(header)),
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proof: BlockHeaderProof.init(proof)))
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func getBlockEpochDataForBlockNumber*(
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a: FinishedAccumulator, bn: UInt256): Result[BlockEpochData, string] =
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let blockNumber = bn.truncate(uint64)
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if blockNumber.isPreMerge:
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let epochIndex = getEpochIndex(blockNumber)
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ok(BlockEpochData(
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epochHash: a.historicalEpochs[epochIndex],
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blockRelativeIndex: getHeaderRecordIndex(blockNumber, epochIndex))
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)
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else:
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err("Block number is post merge: " & $blockNumber)
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