# beacon_chain # Copyright (c) 2018-2021 Status Research & Development GmbH # Licensed and distributed under either of # * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT). # * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0). # at your option. This file may not be copied, modified, or distributed except according to those terms. {.push raises: [Defect].} import std/tables, chronicles, stew/[assign2, results], eth/keys, ../extras, ../beacon_clock, ../spec/[crypto, datatypes, digest, helpers, signatures, signatures_batch, state_transition], ./block_pools_types, ./blockchain_dag, ./block_quarantine export results # Clearance # --------------------------------------------- # # This module is in charge of making the # "quarantined" network blocks # pass the firewall and be stored in the chain DAG logScope: topics = "clearance" template asSigVerified(x: SignedBeaconBlock): SigVerifiedSignedBeaconBlock = ## This converts a signed beacon block to a sig verified beacon clock. ## This assumes that their bytes representation is the same. ## ## At the GC-level, the GC is type-agnostic it's all type erased so ## casting between seq[Attestation] and seq[TrustedAttestation] ## will not disrupt GC operations. ## ## This SHOULD be used in function calls to avoid expensive temporary. ## see https://github.com/status-im/nimbus-eth2/pull/2250#discussion_r562010679 cast[ptr SigVerifiedSignedBeaconBlock](signedBlock.unsafeAddr)[] template asTrusted(x: SignedBeaconBlock or SigVerifiedBeaconBlock): TrustedSignedBeaconBlock = ## This converts a sigverified beacon block to a trusted beacon clock. ## This assumes that their bytes representation is the same. ## ## At the GC-level, the GC is type-agnostic it's all type erased so ## casting between seq[Attestation] and seq[TrustedAttestation] ## will not disrupt GC operations. ## ## This SHOULD be used in function calls to avoid expensive temporary. ## see https://github.com/status-im/nimbus-eth2/pull/2250#discussion_r562010679 cast[ptr TrustedSignedBeaconBlock](signedBlock.unsafeAddr)[] func getOrResolve*(dag: ChainDAGRef, quarantine: var QuarantineRef, root: Eth2Digest): BlockRef = ## Fetch a block ref, or nil if not found (will be added to list of ## blocks-to-resolve) result = dag.getRef(root) if result.isNil: quarantine.addMissing(root) proc batchVerify(quarantine: var QuarantineRef, sigs: openArray[SignatureSet]): bool = var secureRandomBytes: array[32, byte] quarantine.rng[].brHmacDrbgGenerate(secureRandomBytes) # TODO: For now only enable serial batch verification return batchVerifySerial(quarantine.sigVerifCache, sigs, secureRandomBytes) proc addRawBlock*( dag: var ChainDAGRef, quarantine: var QuarantineRef, signedBlock: SignedBeaconBlock, onBlockAdded: OnBlockAdded ): Result[BlockRef, (ValidationResult, BlockError)] {.gcsafe.} proc addResolvedBlock( dag: var ChainDAGRef, quarantine: var QuarantineRef, state: var StateData, trustedBlock: TrustedSignedBeaconBlock, parent: BlockRef, cache: var StateCache, onBlockAdded: OnBlockAdded ) = # TODO move quarantine processing out of here doAssert getStateField(state, slot) == trustedBlock.message.slot, "state must match block" doAssert state.blck.root == trustedBlock.message.parent_root, "the StateData passed into the addResolved function not yet updated!" let blockRoot = trustedBlock.root blockRef = BlockRef.init(blockRoot, trustedBlock.message) blockEpoch = blockRef.slot.compute_epoch_at_slot() link(parent, blockRef) var epochRef = dag.findEpochRef(parent, blockEpoch) if epochRef == nil: let prevEpochRef = if blockEpoch < 1: nil else: dag.findEpochRef(parent, blockEpoch - 1) epochRef = EpochRef.init(state.data.data, cache, prevEpochRef) dag.addEpochRef(blockRef, epochRef) dag.blocks.incl(KeyedBlockRef.init(blockRef)) trace "Populating block dag", key = blockRoot, val = blockRef # Resolved blocks should be stored in database dag.putBlock(trustedBlock) var foundHead: BlockRef for head in dag.heads.mitems(): if head.isAncestorOf(blockRef): head = blockRef foundHead = head break if foundHead.isNil: foundHead = blockRef dag.heads.add(foundHead) debug "Block resolved", blck = shortLog(trustedBlock.message), blockRoot = shortLog(blockRoot), heads = dag.heads.len() state.blck = blockRef # Notify others of the new block before processing the quarantine, such that # notifications for parents happens before those of the children if onBlockAdded != nil: onBlockAdded(blockRef, trustedBlock, epochRef, state.data) # Now that we have the new block, we should see if any of the previously # unresolved blocks magically become resolved # TODO This code is convoluted because when there are more than ~1.5k # blocks being synced, there's a stack overflow as `add` gets called # for the whole chain of blocks. Instead we use this ugly field in `dag` # which could be avoided by refactoring the code # TODO unit test the logic, in particular interaction with fork choice block parents if not quarantine.inAdd: quarantine.inAdd = true defer: quarantine.inAdd = false var entries = 0 while entries != quarantine.orphans.len: entries = quarantine.orphans.len # keep going while quarantine is shrinking var resolved: seq[SignedBeaconBlock] for _, v in quarantine.orphans: if v.message.parent_root in dag: resolved.add(v) for v in resolved: discard addRawBlock(dag, quarantine, v, onBlockAdded) proc addRawBlockCheckStateTransition( dag: var ChainDAGRef, quarantine: var QuarantineRef, signedBlock: SomeSignedBeaconBlock, cache: var StateCache ): (ValidationResult, BlockError) = ## addRawBlock - Ensure block can be applied on a state let poolPtr = unsafeAddr dag # safe because restore is short-lived func restore(v: var HashedBeaconState) = # TODO address this ugly workaround - there should probably be a # `state_transition` that takes a `StateData` instead and updates # the block as well doAssert v.addr == addr poolPtr.clearanceState.data assign(poolPtr.clearanceState, poolPtr.headState) if not state_transition(dag.runtimePreset, dag.clearanceState.data, signedBlock, cache, dag.updateFlags + {slotProcessed}, restore): info "Invalid block" return (ValidationResult.Reject, Invalid) return (ValidationResult.Accept, default(BlockError)) proc addRawBlockKnownParent( dag: var ChainDAGRef, quarantine: var QuarantineRef, signedBlock: SignedBeaconBlock, parent: BlockRef, onBlockAdded: OnBlockAdded ): Result[BlockRef, (ValidationResult, BlockError)] = ## addRawBlock - Block has a parent if parent.slot >= signedBlock.message.slot: # A block whose parent is newer than the block itself is clearly invalid - # discard it immediately debug "Invalid block slot", parentBlock = shortLog(parent) return err((ValidationResult.Reject, Invalid)) if (parent.slot < dag.finalizedHead.slot) or (parent.slot == dag.finalizedHead.slot and parent != dag.finalizedHead.blck): # We finalized a block that's newer than the parent of this block - this # block, although recent, is thus building on a history we're no longer # interested in pursuing. This can happen if a client produces a block # while syncing - ie it's own head block will be old, but it'll create # a block according to the wall clock, in its own little world - this is # correct - from their point of view, the head block they have is the # latest thing that happened on the chain and they're performing their # duty correctly. debug "Unviable block, dropping", finalizedHead = shortLog(dag.finalizedHead), tail = shortLog(dag.tail) return err((ValidationResult.Ignore, Unviable)) # The block might have been in either of `orphans` or `missing` - we don't # want any more work done on its behalf quarantine.removeOrphan(signedBlock) # The block is resolved, now it's time to validate it to ensure that the # blocks we add to the database are clean for the given state # TODO if the block is from the future, we should not be resolving it (yet), # but maybe we should use it as a hint that our clock is wrong? var cache = StateCache() updateStateData( dag, dag.clearanceState, parent.atSlot(signedBlock.message.slot), true, cache) # First batch verify crypto if skipBLSValidation notin dag.updateFlags: # TODO: remove skipBLSValidation var sigs: seq[SignatureSet] if not sigs.collectSignatureSets(signedBlock, dag.clearanceState.data.data, cache): # A PublicKey or Signature isn't on the BLS12-381 curve return err((ValidationResult.Reject, Invalid)) if not quarantine.batchVerify(sigs): return err((ValidationResult.Reject, Invalid)) static: doAssert sizeof(SignedBeaconBlock) == sizeof(SigVerifiedSignedBeaconBlock) let (valRes, blockErr) = addRawBlockCheckStateTransition( dag, quarantine, signedBlock.asSigVerified(), cache) if valRes != ValidationResult.Accept: return err((valRes, blockErr)) # Careful, clearanceState.data has been updated but not blck - we need to # create the BlockRef first! addResolvedBlock( dag, quarantine, dag.clearanceState, signedBlock.asTrusted(), parent, cache, onBlockAdded) return ok dag.clearanceState.blck proc addRawBlockUnresolved( dag: var ChainDAGRef, quarantine: var QuarantineRef, signedBlock: SignedBeaconBlock ): Result[BlockRef, (ValidationResult, BlockError)] = ## addRawBlock - Block is unresolved / has no parent # This is an unresolved block - add it to the quarantine, which will cause its # parent to be scheduled for downloading if not quarantine.add(dag, signedBlock): debug "Block quarantine full" if signedBlock.message.parent_root in quarantine.missing or containsOrphan(quarantine, signedBlock): debug "Unresolved block (parent missing or orphaned)", orphans = quarantine.orphans.len, missing = quarantine.missing.len return err((ValidationResult.Ignore, MissingParent)) # TODO if we receive spam blocks, one heurestic to implement might be to wait # for a couple of attestations to appear before fetching parents - this # would help prevent using up network resources for spam - this serves # two purposes: one is that attestations are likely to appear for the # block only if it's valid / not spam - the other is that malicious # validators that are not proposers can sign invalid blocks and send # them out without penalty - but signing invalid attestations carries # a risk of being slashed, making attestations a more valuable spam # filter. debug "Unresolved block (parent missing)", orphans = quarantine.orphans.len, missing = quarantine.missing.len return err((ValidationResult.Ignore, MissingParent)) proc addRawBlock*( dag: var ChainDAGRef, quarantine: var QuarantineRef, signedBlock: SignedBeaconBlock, onBlockAdded: OnBlockAdded ): Result[BlockRef, (ValidationResult, BlockError)] = ## Try adding a block to the chain, verifying first that it passes the state ## transition function and contains correct cryptographic signature. ## ## Cryptographic checks can be skipped by adding skipBLSValidation to dag.updateFlags logScope: blck = shortLog(signedBlock.message) blockRoot = shortLog(signedBlock.root) template blck(): untyped = signedBlock.message # shortcuts without copy template blockRoot(): untyped = signedBlock.root if blockRoot in dag: debug "Block already exists" # We should not call the block added callback for blocks that already # existed in the pool, as that may confuse consumers such as the fork # choice. While the validation result won't be accessed, it's IGNORE, # according to the spec. return err((ValidationResult.Ignore, Duplicate)) quarantine.missing.del(blockRoot) # If the block we get is older than what we finalized already, we drop it. # One way this can happen is that we start resolving a block and finalization # happens in the meantime - the block we requested will then be stale # by the time it gets here. if blck.slot <= dag.finalizedHead.slot: debug "Old block, dropping", finalizedHead = shortLog(dag.finalizedHead), tail = shortLog(dag.tail) # Doesn't correspond to any specific validation condition, and still won't # be used, but certainly would be IGNORE. return err((ValidationResult.Ignore, Unviable)) let parent = dag.getRef(blck.parent_root) if parent != nil: return addRawBlockKnownParent(dag, quarantine, signedBlock, parent, onBlockAdded) return addRawBlockUnresolved(dag, quarantine, signedBlock)