161 lines
3.7 KiB
Nim
161 lines
3.7 KiB
Nim
## Nim-Dagger
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## Copyright (c) 2022 Status Research & Development GmbH
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## Licensed under either of
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## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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## * MIT license ([LICENSE-MIT](LICENSE-MIT))
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## at your option.
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## This file may not be copied, modified, or distributed except according to
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## those terms.
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import pkg/upraises
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push: {.upraises: [].}
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import std/tables
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import pkg/libp2p/protobuf/minprotobuf
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import pkg/libp2p
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import pkg/questionable
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import pkg/questionable/results
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import pkg/chronicles
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import ../errors
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import ../blocktype
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template EmptyDigests: untyped =
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var
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emptyDigests {.global, threadvar.}:
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array[CIDv0..CIDv1, Table[MultiCodec, MultiHash]]
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once:
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emptyDigests = [
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CIDv0: {
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multiCodec("sha2-256"): Cid
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.init("bafybeihdwdcefgh4dqkjv67uzcmw7ojee6xedzdetojuzjevtenxquvyku")
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.get()
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.mhash
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.get()
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}.toTable,
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CIDv1: {
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multiCodec("sha2-256"): Cid
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.init("QmdfTbBqBPQ7VNxZEYEj14VmRuZBkqFbiwReogJgS1zR1n")
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.get()
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.mhash
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.get()
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}.toTable,
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]
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emptyDigests
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type
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Manifest* = ref object of RootObj
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rootHash*: ?Cid # root (tree) hash of the contained data set
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blockSize*: int # size of each contained block (might not be needed if blocks are len-prefixed)
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blocks*: seq[Cid] # block Cid
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version*: CidVersion # Cid version
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hcodec*: MultiCodec # Multihash codec
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codec*: MultiCodec # Data set codec
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func len*(self: Manifest): int =
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self.blocks.len
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func size*(self: Manifest): int =
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self.blocks.len * self.blockSize
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func `[]`*(self: Manifest, i: Natural): Cid =
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self.blocks[i]
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func `[]=`*(self: var Manifest, i: Natural, item: Cid) =
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self.rootHash = Cid.none
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self.blocks[i] = item
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func `[]`*(self: Manifest, i: BackwardsIndex): Cid =
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self.blocks[self.len - i.int]
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func `[]=`*(self: Manifest, i: BackwardsIndex, item: Cid) =
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self.rootHash = Cid.none
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self.blocks[self.len - i.int] = item
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proc add*(self: Manifest, cid: Cid) =
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self.rootHash = Cid.none
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trace "Adding cid to manifest", cid
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self.blocks.add(cid)
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iterator items*(self: Manifest): Cid =
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for b in self.blocks:
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yield b
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func contains*(self: Manifest, cid: Cid): bool =
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cid in self.blocks
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template hashBytes(mh: MultiHash): seq[byte] =
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## get the hash bytes of a multihash object
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##
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mh.data.buffer[mh.dpos..(mh.dpos + mh.size - 1)]
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proc makeRoot*(self: Manifest): ?!void =
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## Create a tree hash root of the contained
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## block hashes
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##
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var
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stack: seq[MultiHash]
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for cid in self:
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stack.add(? cid.mhash.mapFailure)
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while stack.len > 1:
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let
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(b1, b2) = (stack.pop(), stack.pop())
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mh = ? MultiHash.digest(
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$self.hcodec,
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(b1.hashBytes() & b2.hashBytes()))
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.mapFailure
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stack.add(mh)
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if stack.len == 1:
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let cid = ? Cid.init(
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self.version,
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self.codec,
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(? EmptyDigests[self.version][self.hcodec].catch))
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.mapFailure
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self.rootHash = cid.some
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ok()
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proc cid*(self: Manifest): ?!Cid =
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## Generate a root hash using the treehash algorithm
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##
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if self.rootHash.isNone:
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? self.makeRoot()
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(!self.rootHash).success
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proc new*(
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T: type Manifest,
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blocks: openArray[Cid] = [],
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version = CIDv1,
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hcodec = multiCodec("sha2-256"),
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codec = multiCodec("raw"),
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blockSize = BlockSize): ?!T =
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## Create a manifest using array of `Cid`s
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##
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if hcodec notin EmptyDigests[version]:
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return failure("Unsupported manifest hash codec!")
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T(
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blocks: @blocks,
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version: version,
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codec: codec,
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hcodec: hcodec,
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blockSize: blockSize
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).success
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proc new*(
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T: type Manifest,
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data: openArray[byte]): ?!T =
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Manifest.decode(data)
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