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Copy ssz code from nimbus-eth2 and adjust to stand on its own
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# ssz_serialization | ||
# 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. | ||
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{.push raises: [Defect].} | ||
{.pragma: raisesssz, raises: [Defect, MalformedSszError, SszSizeMismatchError].} | ||
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## SSZ serialization for core SSZ types, as specified in: | ||
# https://github.com/ethereum/consensus-specs/blob/v1.0.1/ssz/simple-serialize.md#serialization | ||
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import | ||
std/typetraits, | ||
stew/[endians2, leb128, objects], | ||
serialization, serialization/testing/tracing, | ||
./ssz_serialization/[codec, bitseqs, types] | ||
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export | ||
serialization, codec, types, bitseqs | ||
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type | ||
SszReader* = object | ||
stream: InputStream | ||
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SszWriter* = object | ||
stream: OutputStream | ||
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SizePrefixed*[T] = distinct T | ||
SszMaxSizeExceeded* = object of SerializationError | ||
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VarSizedWriterCtx = object | ||
fixedParts: WriteCursor | ||
offset: int | ||
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FixedSizedWriterCtx = object | ||
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serializationFormat SSZ | ||
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SSZ.setReader SszReader | ||
SSZ.setWriter SszWriter, PreferredOutput = seq[byte] | ||
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template sizePrefixed*[TT](x: TT): untyped = | ||
type T = TT | ||
SizePrefixed[T](x) | ||
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proc init*(T: type SszReader, | ||
stream: InputStream): T = | ||
T(stream: stream) | ||
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proc writeFixedSized(s: var (OutputStream|WriteCursor), x: auto) {.raises: [Defect, IOError].} = | ||
mixin toSszType | ||
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when x is byte: | ||
s.write x | ||
elif x is bool: | ||
s.write byte(ord(x)) | ||
elif x is UintN: | ||
when cpuEndian == bigEndian: | ||
s.write toBytesLE(x) | ||
else: | ||
s.writeMemCopy x | ||
elif x is array: | ||
when x[0] is byte: | ||
trs "APPENDING FIXED SIZE BYTES", x | ||
s.write x | ||
else: | ||
for elem in x: | ||
trs "WRITING FIXED SIZE ARRAY ELEMENT" | ||
s.writeFixedSized toSszType(elem) | ||
elif x is tuple|object: | ||
enumInstanceSerializedFields(x, fieldName, field): | ||
trs "WRITING FIXED SIZE FIELD", fieldName | ||
s.writeFixedSized toSszType(field) | ||
else: | ||
unsupported x.type | ||
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template writeOffset(cursor: var WriteCursor, offset: int) = | ||
write cursor, toBytesLE(uint32 offset) | ||
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template supports*(_: type SSZ, T: type): bool = | ||
mixin toSszType | ||
anonConst compiles(fixedPortionSize toSszType(declval T)) | ||
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func init*(T: type SszWriter, stream: OutputStream): T = | ||
result.stream = stream | ||
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proc writeVarSizeType(w: var SszWriter, value: auto) {.gcsafe, raises: [Defect, IOError].} | ||
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proc beginRecord*(w: var SszWriter, TT: type): auto = | ||
type T = TT | ||
when isFixedSize(T): | ||
FixedSizedWriterCtx() | ||
else: | ||
const offset = when T is array|HashArray: len(T) * offsetSize | ||
else: fixedPortionSize(T) | ||
VarSizedWriterCtx(offset: offset, | ||
fixedParts: w.stream.delayFixedSizeWrite(offset)) | ||
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template writeField*(w: var SszWriter, | ||
ctx: var auto, | ||
fieldName: string, | ||
field: auto) = | ||
mixin toSszType | ||
when ctx is FixedSizedWriterCtx: | ||
writeFixedSized(w.stream, toSszType(field)) | ||
else: | ||
type FieldType = type toSszType(field) | ||
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when isFixedSize(FieldType): | ||
writeFixedSized(ctx.fixedParts, toSszType(field)) | ||
else: | ||
trs "WRITING OFFSET ", ctx.offset, " FOR ", fieldName | ||
writeOffset(ctx.fixedParts, ctx.offset) | ||
let initPos = w.stream.pos | ||
trs "WRITING VAR SIZE VALUE OF TYPE ", name(FieldType) | ||
when FieldType is BitList: | ||
trs "BIT SEQ ", bytes(field) | ||
writeVarSizeType(w, toSszType(field)) | ||
ctx.offset += w.stream.pos - initPos | ||
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template endRecord*(w: var SszWriter, ctx: var auto) = | ||
when ctx is VarSizedWriterCtx: | ||
finalize ctx.fixedParts | ||
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proc writeSeq[T](w: var SszWriter, value: seq[T]) | ||
{.raises: [Defect, IOError].} = | ||
# Please note that `writeSeq` exists in order to reduce the code bloat | ||
# produced from generic instantiations of the unique `List[N, T]` types. | ||
when isFixedSize(T): | ||
trs "WRITING LIST WITH FIXED SIZE ELEMENTS" | ||
for elem in value: | ||
w.stream.writeFixedSized toSszType(elem) | ||
trs "DONE" | ||
else: | ||
trs "WRITING LIST WITH VAR SIZE ELEMENTS" | ||
var offset = value.len * offsetSize | ||
var cursor = w.stream.delayFixedSizeWrite offset | ||
for elem in value: | ||
cursor.writeFixedSized uint32(offset) | ||
let initPos = w.stream.pos | ||
w.writeVarSizeType toSszType(elem) | ||
offset += w.stream.pos - initPos | ||
finalize cursor | ||
trs "DONE" | ||
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proc writeVarSizeType(w: var SszWriter, value: auto) {.raises: [Defect, IOError].} = | ||
trs "STARTING VAR SIZE TYPE" | ||
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when value is HashArray|HashList: | ||
writeVarSizeType(w, value.data) | ||
elif value is SingleMemberUnion: | ||
doAssert value.selector == 0'u8 | ||
w.writeValue 0'u8 | ||
w.writeValue value.value | ||
elif value is List: | ||
# We reduce code bloat by forwarding all `List` types to a general `seq[T]` proc. | ||
writeSeq(w, asSeq value) | ||
elif value is BitList: | ||
# ATTENTION! We can reuse `writeSeq` only as long as our BitList type is implemented | ||
# to internally match the binary representation of SSZ BitLists in memory. | ||
writeSeq(w, bytes value) | ||
elif value is object|tuple|array: | ||
trs "WRITING OBJECT OR ARRAY" | ||
var ctx = beginRecord(w, type value) | ||
enumerateSubFields(value, field): | ||
writeField w, ctx, astToStr(field), field | ||
endRecord w, ctx | ||
else: | ||
unsupported type(value) | ||
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proc writeValue*(w: var SszWriter, x: auto) {.gcsafe, raises: [Defect, IOError].} = | ||
mixin toSszType | ||
type T = type toSszType(x) | ||
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when isFixedSize(T): | ||
w.stream.writeFixedSized toSszType(x) | ||
else: | ||
w.writeVarSizeType toSszType(x) | ||
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func sszSize*(value: auto): int {.gcsafe, raises: [Defect].} | ||
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func sszSizeForVarSizeList[T](value: openArray[T]): int = | ||
result = len(value) * offsetSize | ||
for elem in value: | ||
result += sszSize(toSszType elem) | ||
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func sszSize*(value: auto): int {.gcsafe, raises: [Defect].} = | ||
mixin toSszType | ||
type T = type toSszType(value) | ||
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when isFixedSize(T): | ||
anonConst fixedPortionSize(T) | ||
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elif T is array|List|HashList|HashArray: | ||
type E = ElemType(T) | ||
when isFixedSize(E): | ||
len(value) * anonConst(fixedPortionSize(E)) | ||
elif T is HashArray: | ||
sszSizeForVarSizeList(value.data) | ||
elif T is array: | ||
sszSizeForVarSizeList(value) | ||
else: | ||
sszSizeForVarSizeList(asSeq value) | ||
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elif T is BitList: | ||
return len(bytes(value)) | ||
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elif T is SingleMemberUnion: | ||
sszSize(toSszType value.value) + 1 | ||
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elif T is object|tuple: | ||
result = anonConst fixedPortionSize(T) | ||
enumInstanceSerializedFields(value, _{.used.}, field): | ||
type FieldType = type toSszType(field) | ||
when not isFixedSize(FieldType): | ||
result += sszSize(toSszType field) | ||
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else: | ||
unsupported T | ||
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proc writeValue*[T](w: var SszWriter, x: SizePrefixed[T]) {.raises: [Defect, IOError].} = | ||
var cursor = w.stream.delayVarSizeWrite(Leb128.maxLen(uint64)) | ||
let initPos = w.stream.pos | ||
w.writeValue T(x) | ||
let length = toBytes(uint64(w.stream.pos - initPos), Leb128) | ||
cursor.finalWrite length.toOpenArray() | ||
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proc readValue*(r: var SszReader, val: var auto) {. | ||
raises: [Defect, MalformedSszError, SszSizeMismatchError, IOError].} = | ||
mixin readSszBytes | ||
type T = type val | ||
when isFixedSize(T): | ||
const minimalSize = fixedPortionSize(T) | ||
if r.stream.readable(minimalSize): | ||
readSszBytes(r.stream.read(minimalSize), val) | ||
else: | ||
raise newException(MalformedSszError, "SSZ input of insufficient size") | ||
else: | ||
# TODO(zah) Read the fixed portion first and precisely measure the | ||
# size of the dynamic portion to consume the right number of bytes. | ||
readSszBytes(r.stream.read(r.stream.len.get), val) | ||
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proc readSszBytes*[T](data: openArray[byte], val: var T) {. | ||
raises: [Defect, MalformedSszError, SszSizeMismatchError].} = | ||
# Overload `readSszBytes` to perform custom operations on T after | ||
# deserialization | ||
mixin readSszValue | ||
readSszValue(data, val) |
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