nim-eth/eth/trie/binaries.nim

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import
sequtils,
stew/ranges/ptr_arith, trie_defs,
./trie_bitseq
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type
TrieNodeKind* = enum
KV_TYPE = 0
BRANCH_TYPE = 1
LEAF_TYPE = 2
TrieNodeKey* = seq[byte]
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TrieNode* = object
case kind*: TrieNodeKind
of KV_TYPE:
keyPath*: TrieBitSeq
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child*: TrieNodeKey
of BRANCH_TYPE:
leftChild*: TrieNodeKey
rightChild*: TrieNodeKey
of LEAF_TYPE:
value*: seq[byte]
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InvalidNode* = object of CorruptedTrieDatabase
ValidationError* = object of CorruptedTrieDatabase
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# ----------------------------------------------
template sliceToEnd*(r: TrieBitSeq, index: int): TrieBitSeq =
if r.len <= index: TrieBitSeq() else: r[index .. ^1]
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proc decodeToBinKeypath*(path: seq[byte]): TrieBitSeq =
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## Decodes bytes into a sequence of 0s and 1s
## Used in decoding key path of a KV-NODE
var path = path.bits
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if path[0]:
path = path[4..^1]
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doAssert path[0] == false
doAssert path[1] == false
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var bits = path[2].int shl 1
bits = bits or path[3].int
if path.len > 4:
path[4+((4 - bits) mod 4)..^1]
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else:
TrieBitSeq()
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proc parseNode*(node: openArray[byte]): TrieNode =
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# Input: a serialized node
if node.len == 0:
raise newException(InvalidNode, "Blank node is not a valid node type in Binary Trie")
if node[0].ord < low(TrieNodeKind).ord or node[0].ord > high(TrieNodeKind).ord:
raise newException(InvalidNode, "Invalid node type")
let nodeType = node[0].TrieNodeKind
case nodeType
of BRANCH_TYPE:
if node.len != 65:
raise newException(InvalidNode, "Invalid branch node, both child node should be 32 bytes long each")
# Output: node type, left child, right child
result = TrieNode(kind: BRANCH_TYPE, leftChild: node[1..<33], rightChild: node[33..^1])
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doAssert(result.leftChild.len == 32)
doAssert(result.rightChild.len == 32)
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return result
of KV_TYPE:
if node.len <= 33:
raise newException(InvalidNode, "Invalid kv node, short of key path or child node hash")
# Output: node type, keypath, child
return TrieNode(kind: KV_TYPE, keyPath: decodeToBinKeypath(node[1..^33]), child: node[^32..^1])
of LEAF_TYPE:
if node.len == 1:
raise newException(InvalidNode, "Invalid leaf node, can not contain empty value")
# Output: node type, value
return TrieNode(kind: LEAF_TYPE, value: node[1..^1])
proc encodeKVNode*(keyPath: TrieBitSeq, childHash: TrieNodeKey): seq[byte] =
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## Serializes a key/value node
if keyPath.len == 0:
raise newException(ValidationError, "Key path can not be empty")
if childHash.len != 32:
raise newException(ValidationError, "Invalid hash len")
# Encodes a sequence of 0s and 1s into tightly packed bytes
# Used in encoding key path of a KV-NODE
# KV-NODE = KV-TYPE-PREFIX + encoded keypath + 32 bytes hash
let
len = keyPath.len
padding = ((not len) + 1) and 3 # modulo 4 padding
paddedBinLen = len + padding
prefix = len mod 4
result = newSeq[byte](((len + padding) div 8) + 34)
result[0] = KV_TYPE.byte
if paddedBinLen mod 8 == 4:
var nbits = 4 - padding
result[1] = byte(prefix shl 4) or byte.fromBits(keyPath, 0, nbits)
for i in 0..<(len div 8):
result[i+2] = byte.fromBits(keyPath, nbits, 8)
inc(nbits, 8)
else:
var nbits = 8 - padding
result[1] = byte(0b1000_0000) or byte(prefix)
result[2] = byte.fromBits(keyPath, 0, nbits)
for i in 0..<((len-1) div 8):
result[i+3] = byte.fromBits(keyPath, nbits, 8)
inc(nbits, 8)
copyMem(result[^32].addr, childHash.baseAddr, 32)
proc encodeKVNode*(keyPath: bool, childHash: TrieNodeKey): seq[byte] =
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result = newSeq[byte](34)
result[0] = KV_TYPE.byte
result[1] = byte(16) or byte(keyPath)
copyMem(result[^32].addr, childHash.baseAddr, 32)
proc encodeBranchNode*(leftChildHash, rightChildHash: TrieNodeKey): seq[byte] =
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## Serializes a branch node
const
BRANCH_TYPE_PREFIX = @[BRANCH_TYPE.byte]
if leftChildHash.len != 32 or rightChildHash.len != 32:
raise newException(ValidationError, "encodeBranchNode: Invalid hash len")
result = BRANCH_TYPE_PREFIX.concat(leftChildHash, rightChildHash)
proc encodeLeafNode*(value: openArray[byte]): seq[byte] =
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## Serializes a leaf node
const
LEAF_TYPE_PREFIX = @[LEAF_TYPE.byte]
if value.len == 0:
raise newException(ValidationError, "Value of leaf node can not be empty")
result = LEAF_TYPE_PREFIX.concat(@value)
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proc getCommonPrefixLength*(a, b: TrieBitSeq): int =
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let len = min(a.len, b.len)
for i in 0..<len:
if a[i] != b[i]: return i
result = len