nimbus-eth1/stateless/witness_from_tree.nim

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import
stew/[byteutils, endians2],
eth/[common, rlp],
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eth/trie/[trie_defs, nibbles, db],
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faststreams/outputs,
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./witness_types, ../nimbus/constants,
../nimbus/db/storage_types, ./multi_keys
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{.push raises: [].}
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type
DB = TrieDatabaseRef
WitnessBuilder* = object
db*: DB
root: KeccakHash
output: OutputStream
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flags: WitnessFlags
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StackElem = object
node: seq[byte]
parentGroup: Group
keys: MultikeysRef
depth: int
storageMode: bool
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proc initWitnessBuilder*(db: DB, rootHash: KeccakHash, flags: WitnessFlags = {}): WitnessBuilder =
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result.db = db
result.root = rootHash
result.output = memoryOutput().s
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result.flags = flags
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template extensionNodeKey(r: Rlp): auto =
hexPrefixDecode r.listElem(0).toBytes
proc expectHash(r: Rlp): seq[byte] {.gcsafe, raises: [RlpError].} =
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result = r.toBytes
if result.len != 32:
raise newException(RlpTypeMismatch,
"RLP expected to be a Keccak hash value, but has an incorrect length")
template getNode(elem: untyped): untyped =
if elem.isList: @(elem.rawData)
else: @(get(wb.db, elem.expectHash))
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proc rlpListToBitmask(r: var Rlp): uint {.gcsafe, raises: [RlpError].} =
# only bit 1st to 16th are valid
# the 1st bit is the rightmost bit
var i = 0
for branch in r:
if not branch.isEmpty:
result.setBranchMaskBit(i)
inc i
r.position = 0
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template write(wb: var WitnessBuilder, x: untyped) =
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wb.output.write(x)
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when defined(debugHash):
proc writeU32Impl(wb: var WitnessBuilder, x: uint32) =
wb.write(toBytesBE(x))
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template writeU32(wb: var WitnessBuilder, x: untyped) =
wb.writeU32Impl(uint32(x))
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template writeByte(wb: var WitnessBuilder, x: untyped) =
wb.write(byte(x))
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proc writeUVarint(wb: var WitnessBuilder, x: SomeUnsignedInt)
{.gcsafe, raises: [IOError].} =
# LEB128 varint encoding
var value = x
while true:
var b = value and 0x7F # low order 7 bits of value
value = value shr 7
if value != 0: # more bytes to come
b = b or 0x80 # set high order bit of b
wb.writeByte(b)
if value == 0: break
template writeUVarint32(wb: var WitnessBuilder, x: untyped) =
wb.writeUVarint(uint32(x))
proc writeUVarint(wb: var WitnessBuilder, x: UInt256)
{.gcsafe, raises: [IOError].} =
# LEB128 varint encoding
var value = x
while true:
# we don't truncate to byte here, int will be faster
var b = value.truncate(int) and 0x7F # low order 7 bits of value
value = value shr 7
if value != 0: # more bytes to come
b = b or 0x80 # set high order bit of b
wb.writeByte(b)
if value == 0: break
proc writeNibbles(wb: var WitnessBuilder; n: NibblesSeq, withLen: bool = true)
{.gcsafe, raises: [IOError].} =
# convert the NibblesSeq into left aligned byte seq
# perhaps we can optimize it if the NibblesSeq already left aligned
let nibblesLen = n.len
let numBytes = nibblesLen div 2 + nibblesLen mod 2
var bytes: array[32, byte]
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doAssert(nibblesLen >= 1 and nibblesLen <= 64)
for pos in 0..<n.len:
if (pos and 1) != 0:
bytes[pos div 2] = bytes[pos div 2] or n[pos]
else:
bytes[pos div 2] = bytes[pos div 2] or (n[pos] shl 4)
if withLen:
# write nibblesLen
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wb.writeByte(nibblesLen)
# write nibbles
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wb.write(bytes.toOpenArray(0, numBytes-1))
proc writeExtensionNode(wb: var WitnessBuilder, n: NibblesSeq, depth: int, node: openArray[byte])
{.gcsafe, raises: [IOError].} =
# write type
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wb.writeByte(ExtensionNodeType)
# write nibbles
wb.writeNibbles(n)
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when defined(debugDepth):
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wb.writeByte(depth)
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when defined(debugHash):
wb.write(keccakHash(node).data)
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proc writeBranchNode(wb: var WitnessBuilder, mask: uint, depth: int, node: openArray[byte])
{.gcsafe, raises: [IOError].} =
# write type
# branch node 17th elem should always empty
doAssert mask.branchMaskBitIsSet(16) == false
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wb.writeByte(BranchNodeType)
# write branch mask
# countOnes(branch mask) >= 2 and <= 16
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wb.writeByte((mask shr 8) and 0xFF)
wb.writeByte(mask and 0xFF)
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when defined(debugDepth):
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wb.writeByte(depth)
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when defined(debugHash):
wb.write(keccakHash(node).data)
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proc writeHashNode(wb: var WitnessBuilder, node: openArray[byte], depth: int, storageMode: bool)
{.gcsafe, raises: [IOError].} =
# usually a hash node means the recursion will not go deeper
# and the information can be represented by the hash
# for chunked witness, a hash node can be a root to another
# sub-trie in one of the chunks
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wb.writeByte(HashNodeType)
if depth >= 9 and storageMode and node[0] == 0.byte:
wb.writeByte(ShortRlpPrefix)
wb.write(node)
proc writeShortRlp(wb: var WitnessBuilder, node: openArray[byte], depth: int, storageMode: bool)
{.gcsafe, raises: [IOError].} =
doAssert(node.len < 32 and depth >= 9 and storageMode)
wb.writeByte(HashNodeType)
wb.writeByte(ShortRlpPrefix)
wb.writeByte(node.len)
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wb.write(node)
proc getBranchRecurse(wb: var WitnessBuilder, z: var StackElem) {.gcsafe, raises: [CatchableError].}
proc writeByteCode(wb: var WitnessBuilder, kd: KeyData, acc: Account, depth: int)
{.gcsafe, raises: [IOError,ContractCodeError].} =
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if not kd.codeTouched:
# the account have code but not touched by the EVM
# in current block execution
wb.writeByte(CodeUntouched)
let code = get(wb.db, contractHashKey(acc.codeHash).toOpenArray)
if wfEIP170 in wb.flags and code.len > EIP170_MAX_CODE_SIZE:
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raise newException(ContractCodeError, "code len exceed EIP170 code size limit")
wb.writeUVarint32(code.len)
wb.writeHashNode(acc.codeHash.data, depth, false)
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# no need to write 'code' here
return
wb.writeByte(CodeTouched)
if acc.codeHash == blankStringHash:
# no code
wb.writeUVarint32(0'u32)
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return
# the account have code and the EVM use it
let code = get(wb.db, contractHashKey(acc.codeHash).toOpenArray)
if wfEIP170 in wb.flags and code.len > EIP170_MAX_CODE_SIZE:
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raise newException(ContractCodeError, "code len exceed EIP170 code size limit")
wb.writeUVarint32(code.len)
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wb.write(code)
proc writeStorage(wb: var WitnessBuilder, kd: KeyData, acc: Account, depth: int)
{.gcsafe, raises: [CatchableError].} =
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if kd.storageKeys.isNil:
# the account have storage but not touched by EVM
wb.writeHashNode(acc.storageRoot.data, depth, true)
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elif acc.storageRoot != emptyRlpHash:
# the account have storage and the EVM use it
var zz = StackElem(
node: wb.db.get(acc.storageRoot.data),
parentGroup: kd.storageKeys.initGroup(),
keys: kd.storageKeys,
depth: 0, # set depth to zero
storageMode: true # switch to storage mode
)
getBranchRecurse(wb, zz)
else:
# no storage at all
wb.writeHashNode(emptyRlpHash.data, depth, true)
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proc writeAccountNode(wb: var WitnessBuilder, kd: KeyData, acc: Account,
node: openArray[byte], depth: int) {.raises: [ContractCodeError, IOError, CatchableError].} =
# write type
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wb.writeByte(AccountNodeType)
when defined(debugHash):
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wb.writeU32(node.len)
wb.write(node)
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when defined(debugDepth):
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wb.writeByte(depth)
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var accountType = if acc.codeHash == blankStringHash and acc.storageRoot == emptyRlpHash: SimpleAccountType
else: ExtendedAccountType
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wb.writeByte(accountType)
wb.write(kd.address)
wb.writeUVarint(acc.balance)
wb.writeUVarint(acc.nonce)
if accountType != SimpleAccountType:
wb.writeByteCode(kd, acc, depth)
wb.writeStorage(kd, acc, depth)
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#0x00 address:<Address> balance:<Bytes32> nonce:<Bytes32>
#0x01 address:<Address> balance:<Bytes32> nonce:<Bytes32> bytecode:<Bytecode> storage:<Tree_Node(0,1)>
proc writeAccountStorageLeafNode(wb: var WitnessBuilder, key: openArray[byte], val: UInt256, node: openArray[byte], depth: int)
{.gcsafe, raises: [IOError].} =
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wb.writeByte(StorageLeafNodeType)
when defined(debugHash):
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wb.writeU32(node.len)
wb.write(node)
when defined(debugDepth):
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wb.writeByte(depth)
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wb.write(key)
wb.write(val.toBytesBE)
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#<Storage_Leaf_Node(d<65)> := key:<Bytes32> val:<Bytes32>
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proc getBranchRecurse(wb: var WitnessBuilder, z: var StackElem) =
if z.node.len == 0: return
if z.node.len < 32:
writeShortRlp(wb, z.node, z.depth, z.storageMode)
return
var nodeRlp = rlpFromBytes z.node
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case nodeRlp.listLen
of 2:
let (isLeaf, k) = nodeRlp.extensionNodeKey
let mg = groups(z.keys, z.depth, k, z.parentGroup)
if not mg.match:
# return immediately if there is no match
writeHashNode(wb, keccakHash(z.node).data, z.depth, z.storageMode)
return
let value = nodeRlp.listElem(1)
if not isLeaf:
# recursion will go deeper depend on the common-prefix length nibbles
writeExtensionNode(wb, k, z.depth, z.node)
var zz = StackElem(
node: value.getNode,
parentGroup: mg.group,
keys: z.keys,
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depth: z.depth + k.len, # increase the depth by k.len
storageMode: z.storageMode
)
getBranchRecurse(wb, zz)
return
# there should be only one match
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let kd = z.keys.visitMatch(mg, z.depth)
if z.storageMode:
doAssert(kd.storageMode)
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writeAccountStorageLeafNode(wb, kd.storageSlot, value.toBytes.decode(UInt256), z.node, z.depth)
else:
doAssert(not kd.storageMode)
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writeAccountNode(wb, kd, value.toBytes.decode(Account), z.node, z.depth)
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of 17:
let branchMask = rlpListToBitmask(nodeRlp)
writeBranchNode(wb, branchMask, z.depth, z.node)
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# if there is a match in any branch elem
# 1st to 16th, the recursion will go deeper
# by one nibble
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doAssert(z.depth != 64) # notLeaf or path.len == 0
let path = groups(z.keys, z.parentGroup, z.depth)
for i in nonEmpty(branchMask):
let branch = nodeRlp.listElem(i)
if branchMaskBitIsSet(path.mask, i):
# it is a match between multikeys and Branch Node elem
var zz = StackElem(
node: branch.getNode,
parentGroup: path.groups[i],
keys: z.keys,
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depth: z.depth + 1, # increase the depth by one
storageMode: z.storageMode
)
getBranchRecurse(wb, zz)
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continue
if branch.isList:
writeShortRlp(wb, branch.rawData, z.depth, z.storageMode)
else:
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# if branch elem not empty and not a match, emit hash
writeHashNode(wb, branch.expectHash, z.depth, z.storageMode)
# 17th elem should always empty
# 17th elem appear in yellow paper but never in
# the actual ethereum state trie
# the 17th elem also not included in block witness spec
doAssert branchMask.branchMaskBitIsSet(16) == false
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else:
raise newException(CorruptedTrieDatabase,
"HexaryTrie node with an unexpected number of children")
proc buildWitness*(wb: var WitnessBuilder, keys: MultikeysRef): seq[byte]
{.raises: [CatchableError].} =
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# witness version
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wb.writeByte(BlockWitnessVersion)
# one or more trees
# we only output one big tree here
# the condition to split the big tree into chunks of sub-tries
# is not clear in the spec
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wb.writeByte(MetadataNothing)
var z = StackElem(
node: @(wb.db.get(wb.root.data)),
parentGroup: keys.initGroup(),
keys: keys,
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depth: 0, # always start with a zero depth
storageMode: false # build account witness first
)
getBranchRecurse(wb, z)
# result
result = wb.output.getOutput(seq[byte])