feat: initialize Kurdistan SDK - independent fork of Polkadot SDK
This commit is contained in:
@@ -0,0 +1,451 @@
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// Copyright (C) Parity Technologies (UK) Ltd.
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// This file is part of Pezkuwi.
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// Pezkuwi is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Pezkuwi is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Pezkuwi. If not, see <http://www.gnu.org/licenses/>.
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//! As part of Pezkuwi's availability system, certain pieces of data
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//! for each block are required to be kept available.
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//!
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//! The way we accomplish this is by erasure coding the data into n pieces
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//! and constructing a merkle root of the data.
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//!
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//! Each of n validators stores their piece of data. We assume `n = 3f + k`, `0 < k ≤ 3`.
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//! f is the maximum number of faulty validators in the system.
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//! The data is coded so any f+1 chunks can be used to reconstruct the full data.
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use codec::{Decode, Encode};
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use pezkuwi_node_primitives::{AvailableData, Proof};
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use pezkuwi_primitives::{BlakeTwo256, Hash as H256, HashT};
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use sp_core::Blake2Hasher;
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use sp_trie::{
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trie_types::{TrieDBBuilder, TrieDBMutBuilderV0 as TrieDBMutBuilder},
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LayoutV0, MemoryDB, Trie, TrieMut, EMPTY_PREFIX,
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};
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use thiserror::Error;
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use novelpoly::{CodeParams, WrappedShard};
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// we are limited to the field order of GF(2^16), which is 65536
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const MAX_VALIDATORS: usize = novelpoly::f2e16::FIELD_SIZE;
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/// Errors in erasure coding.
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#[derive(Debug, Clone, PartialEq, Error)]
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pub enum Error {
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/// Returned when there are too many validators.
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#[error("There are too many validators")]
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TooManyValidators,
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/// Cannot encode something for zero or one validator
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#[error("Expected at least 2 validators")]
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NotEnoughValidators,
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/// Cannot reconstruct: wrong number of validators.
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#[error("Validator count mismatches between encoding and decoding")]
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WrongValidatorCount,
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/// Not enough chunks present.
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#[error("Not enough chunks to reconstruct message")]
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NotEnoughChunks,
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/// Too many chunks present.
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#[error("Too many chunks present")]
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TooManyChunks,
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/// Chunks not of uniform length or the chunks are empty.
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#[error("Chunks are not uniform, mismatch in length or are zero sized")]
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NonUniformChunks,
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/// An uneven byte-length of a shard is not valid for `GF(2^16)` encoding.
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#[error("Uneven length is not valid for field GF(2^16)")]
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UnevenLength,
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/// Chunk index out of bounds.
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#[error("Chunk is out of bounds: {chunk_index} not included in 0..{n_validators}")]
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ChunkIndexOutOfBounds { chunk_index: usize, n_validators: usize },
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/// Bad payload in reconstructed bytes.
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#[error("Reconstructed payload invalid")]
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BadPayload,
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/// Unable to decode reconstructed bytes.
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#[error("Unable to decode reconstructed payload: {0}")]
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Decode(#[source] codec::Error),
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/// Invalid branch proof.
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#[error("Invalid branch proof")]
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InvalidBranchProof,
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/// Branch out of bounds.
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#[error("Branch is out of bounds")]
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BranchOutOfBounds,
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/// Unknown error
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#[error("An unknown error has appeared when reconstructing erasure code chunks")]
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UnknownReconstruction,
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/// Unknown error
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#[error("An unknown error has appeared when deriving code parameters from validator count")]
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UnknownCodeParam,
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}
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impl From<novelpoly::Error> for Error {
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fn from(error: novelpoly::Error) -> Self {
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match error {
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novelpoly::Error::NeedMoreShards { .. } => Self::NotEnoughChunks,
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novelpoly::Error::ParamterMustBePowerOf2 { .. } => Self::UnevenLength,
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novelpoly::Error::WantedShardCountTooHigh(_) => Self::TooManyValidators,
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novelpoly::Error::WantedShardCountTooLow(_) => Self::NotEnoughValidators,
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novelpoly::Error::PayloadSizeIsZero { .. } => Self::BadPayload,
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novelpoly::Error::InconsistentShardLengths { .. } => Self::NonUniformChunks,
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_ => Self::UnknownReconstruction,
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}
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}
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}
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/// Obtain a threshold of chunks that should be enough to recover the data.
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pub const fn recovery_threshold(n_validators: usize) -> Result<usize, Error> {
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if n_validators > MAX_VALIDATORS {
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return Err(Error::TooManyValidators);
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}
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if n_validators <= 1 {
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return Err(Error::NotEnoughValidators);
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}
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let needed = n_validators.saturating_sub(1) / 3;
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Ok(needed + 1)
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}
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/// Obtain the threshold of systematic chunks that should be enough to recover the data.
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///
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/// If the regular `recovery_threshold` is a power of two, then it returns the same value.
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/// Otherwise, it returns the next lower power of two.
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pub fn systematic_recovery_threshold(n_validators: usize) -> Result<usize, Error> {
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code_params(n_validators).map(|params| params.k())
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}
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fn code_params(n_validators: usize) -> Result<CodeParams, Error> {
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// we need to be able to reconstruct from 1/3 - eps
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let n_wanted = n_validators;
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let k_wanted = recovery_threshold(n_wanted)?;
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if n_wanted > MAX_VALIDATORS as usize {
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return Err(Error::TooManyValidators);
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}
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CodeParams::derive_parameters(n_wanted, k_wanted).map_err(|e| match e {
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novelpoly::Error::WantedShardCountTooHigh(_) => Error::TooManyValidators,
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novelpoly::Error::WantedShardCountTooLow(_) => Error::NotEnoughValidators,
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_ => Error::UnknownCodeParam,
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})
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}
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/// Reconstruct the v1 available data from the set of systematic chunks.
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///
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/// Provide a vector containing chunk data. If too few chunks are provided, recovery is not
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/// possible.
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pub fn reconstruct_from_systematic_v1(
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n_validators: usize,
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chunks: Vec<Vec<u8>>,
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) -> Result<AvailableData, Error> {
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reconstruct_from_systematic(n_validators, chunks)
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}
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/// Reconstruct the available data from the set of systematic chunks.
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///
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/// Provide a vector containing the first k chunks in order. If too few chunks are provided,
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/// recovery is not possible.
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pub fn reconstruct_from_systematic<T: Decode>(
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n_validators: usize,
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chunks: Vec<Vec<u8>>,
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) -> Result<T, Error> {
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let code_params = code_params(n_validators)?;
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let k = code_params.k();
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for chunk_data in chunks.iter().take(k) {
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if !chunk_data.len().is_multiple_of(2) {
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return Err(Error::UnevenLength);
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}
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}
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let bytes = code_params.make_encoder().reconstruct_from_systematic(
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chunks.into_iter().take(k).map(|data| WrappedShard::new(data)).collect(),
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)?;
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Decode::decode(&mut &bytes[..]).map_err(|err| Error::Decode(err))
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}
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/// Obtain erasure-coded chunks for v1 `AvailableData`, one for each validator.
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///
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/// Works only up to 65536 validators, and `n_validators` must be non-zero.
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pub fn obtain_chunks_v1(n_validators: usize, data: &AvailableData) -> Result<Vec<Vec<u8>>, Error> {
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obtain_chunks(n_validators, data)
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}
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/// Obtain erasure-coded chunks, one for each validator.
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///
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/// Works only up to 65536 validators, and `n_validators` must be non-zero.
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pub fn obtain_chunks<T: Encode>(n_validators: usize, data: &T) -> Result<Vec<Vec<u8>>, Error> {
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let params = code_params(n_validators)?;
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let encoded = data.encode();
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if encoded.is_empty() {
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return Err(Error::BadPayload);
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}
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let shards = params
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.make_encoder()
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.encode::<WrappedShard>(&encoded[..])
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.expect("Payload non-empty, shard sizes are uniform, and validator numbers checked; qed");
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Ok(shards.into_iter().map(|w: WrappedShard| w.into_inner()).collect())
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}
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/// Reconstruct the v1 available data from a set of chunks.
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///
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/// Provide an iterator containing chunk data and the corresponding index.
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/// The indices of the present chunks must be indicated. If too few chunks
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/// are provided, recovery is not possible.
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///
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/// Works only up to 65536 validators, and `n_validators` must be non-zero.
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pub fn reconstruct_v1<'a, I: 'a>(n_validators: usize, chunks: I) -> Result<AvailableData, Error>
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where
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I: IntoIterator<Item = (&'a [u8], usize)>,
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{
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reconstruct(n_validators, chunks)
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}
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/// Reconstruct decodable data from a set of chunks.
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///
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/// Provide an iterator containing chunk data and the corresponding index.
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/// The indices of the present chunks must be indicated. If too few chunks
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/// are provided, recovery is not possible.
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///
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/// Works only up to 65536 validators, and `n_validators` must be non-zero.
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pub fn reconstruct<'a, I: 'a, T: Decode>(n_validators: usize, chunks: I) -> Result<T, Error>
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where
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I: IntoIterator<Item = (&'a [u8], usize)>,
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{
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let params = code_params(n_validators)?;
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let mut received_shards: Vec<Option<WrappedShard>> = vec![None; n_validators];
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for (chunk_data, chunk_idx) in chunks.into_iter().take(n_validators) {
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if !chunk_data.len().is_multiple_of(2) {
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return Err(Error::UnevenLength);
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}
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received_shards[chunk_idx] = Some(WrappedShard::new(chunk_data.to_vec()));
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}
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let payload_bytes = params.make_encoder().reconstruct(received_shards)?;
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Decode::decode(&mut &payload_bytes[..]).map_err(|_| Error::BadPayload)
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}
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/// An iterator that yields merkle branches and chunk data for all chunks to
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/// be sent to other validators.
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pub struct Branches<'a, I> {
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trie_storage: MemoryDB<Blake2Hasher>,
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root: H256,
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chunks: &'a [I],
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current_pos: usize,
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}
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impl<'a, I: AsRef<[u8]>> Branches<'a, I> {
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/// Get the trie root.
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pub fn root(&self) -> H256 {
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self.root
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}
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}
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impl<'a, I: AsRef<[u8]>> Iterator for Branches<'a, I> {
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type Item = (Proof, &'a [u8]);
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fn next(&mut self) -> Option<Self::Item> {
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use sp_trie::Recorder;
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let mut recorder = Recorder::<LayoutV0<Blake2Hasher>>::new();
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let res = {
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let trie = TrieDBBuilder::new(&self.trie_storage, &self.root)
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.with_recorder(&mut recorder)
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.build();
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(self.current_pos as u32).using_encoded(|s| trie.get(s))
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};
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match res.expect("all nodes in trie present; qed") {
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Some(_) => {
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let nodes: Vec<Vec<u8>> = recorder.drain().into_iter().map(|r| r.data).collect();
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let chunk = self.chunks.get(self.current_pos).expect(
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"there is a one-to-one mapping of chunks to valid merkle branches; qed",
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);
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self.current_pos += 1;
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Proof::try_from(nodes).ok().map(|proof| (proof, chunk.as_ref()))
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},
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None => None,
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}
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}
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}
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/// Construct a trie from chunks of an erasure-coded value. This returns the root hash and an
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/// iterator of merkle proofs, one for each validator.
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pub fn branches<'a, I: 'a>(chunks: &'a [I]) -> Branches<'a, I>
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where
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I: AsRef<[u8]>,
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{
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let mut trie_storage: MemoryDB<Blake2Hasher> = MemoryDB::default();
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let mut root = H256::default();
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// construct trie mapping each chunk's index to its hash.
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{
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let mut trie = TrieDBMutBuilder::new(&mut trie_storage, &mut root).build();
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for (i, chunk) in chunks.as_ref().iter().enumerate() {
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(i as u32).using_encoded(|encoded_index| {
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let chunk_hash = BlakeTwo256::hash(chunk.as_ref());
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trie.insert(encoded_index, chunk_hash.as_ref())
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.expect("a fresh trie stored in memory cannot have errors loading nodes; qed");
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})
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}
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}
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Branches { trie_storage, root, chunks, current_pos: 0 }
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}
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/// Verify a merkle branch, yielding the chunk hash meant to be present at that
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/// index.
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pub fn branch_hash(root: &H256, branch_nodes: &Proof, index: usize) -> Result<H256, Error> {
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let mut trie_storage: MemoryDB<Blake2Hasher> = MemoryDB::default();
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for node in branch_nodes.iter() {
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(&mut trie_storage as &mut sp_trie::HashDB<_>).insert(EMPTY_PREFIX, node);
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}
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let trie = TrieDBBuilder::new(&trie_storage, &root).build();
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let res = (index as u32).using_encoded(|key| {
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trie.get_with(key, |raw_hash: &[u8]| H256::decode(&mut &raw_hash[..]))
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});
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match res {
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Ok(Some(Ok(hash))) => Ok(hash),
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Ok(Some(Err(_))) => Err(Error::InvalidBranchProof), // hash failed to decode
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Ok(None) => Err(Error::BranchOutOfBounds),
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Err(_) => Err(Error::InvalidBranchProof),
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}
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}
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#[cfg(test)]
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mod tests {
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use std::sync::Arc;
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use super::*;
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use pezkuwi_node_primitives::{AvailableData, BlockData, PoV};
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use pezkuwi_primitives::{HeadData, PersistedValidationData};
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use quickcheck::{Arbitrary, Gen, QuickCheck};
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// In order to adequately compute the number of entries in the Merkle
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// trie, we must account for the fixed 16-ary trie structure.
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const KEY_INDEX_NIBBLE_SIZE: usize = 4;
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#[derive(Clone, Debug)]
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struct ArbitraryAvailableData(AvailableData);
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impl Arbitrary for ArbitraryAvailableData {
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fn arbitrary(g: &mut Gen) -> Self {
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// Limit the POV len to 1 mib, otherwise the test will take forever
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let pov_len = (u32::arbitrary(g) % (1024 * 1024)).max(2);
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let pov = (0..pov_len).map(|_| u8::arbitrary(g)).collect();
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let pvd = PersistedValidationData {
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parent_head: HeadData((0..u16::arbitrary(g)).map(|_| u8::arbitrary(g)).collect()),
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relay_parent_number: u32::arbitrary(g),
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relay_parent_storage_root: [u8::arbitrary(g); 32].into(),
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max_pov_size: u32::arbitrary(g),
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};
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ArbitraryAvailableData(AvailableData {
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pov: Arc::new(PoV { block_data: BlockData(pov) }),
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validation_data: pvd,
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})
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}
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}
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#[test]
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fn field_order_is_right_size() {
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assert_eq!(MAX_VALIDATORS, 65536);
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}
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#[test]
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fn round_trip_works() {
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let pov = PoV { block_data: BlockData((0..255).collect()) };
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let available_data = AvailableData { pov: pov.into(), validation_data: Default::default() };
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let chunks = obtain_chunks(10, &available_data).unwrap();
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assert_eq!(chunks.len(), 10);
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// any 4 chunks should work.
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let reconstructed: AvailableData = reconstruct(
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10,
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[(&*chunks[1], 1), (&*chunks[4], 4), (&*chunks[6], 6), (&*chunks[9], 9)]
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.iter()
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.cloned(),
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)
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.unwrap();
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assert_eq!(reconstructed, available_data);
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}
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#[test]
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fn round_trip_systematic_works() {
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fn property(available_data: ArbitraryAvailableData, n_validators: u16) {
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let n_validators = n_validators.max(2);
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let kpow2 = systematic_recovery_threshold(n_validators as usize).unwrap();
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let chunks = obtain_chunks(n_validators as usize, &available_data.0).unwrap();
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assert_eq!(
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reconstruct_from_systematic_v1(
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n_validators as usize,
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chunks.into_iter().take(kpow2).collect()
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)
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.unwrap(),
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available_data.0
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);
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}
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QuickCheck::new().quickcheck(property as fn(ArbitraryAvailableData, u16))
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}
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#[test]
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fn reconstruct_does_not_panic_on_low_validator_count() {
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let reconstructed = reconstruct_v1(1, [].iter().cloned());
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assert_eq!(reconstructed, Err(Error::NotEnoughValidators));
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}
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fn generate_trie_and_generate_proofs(magnitude: u32) {
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let n_validators = 2_u32.pow(magnitude) as usize;
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let pov = PoV { block_data: BlockData(vec![2; n_validators / KEY_INDEX_NIBBLE_SIZE]) };
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let available_data = AvailableData { pov: pov.into(), validation_data: Default::default() };
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let chunks = obtain_chunks(magnitude as usize, &available_data).unwrap();
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assert_eq!(chunks.len() as u32, magnitude);
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let branches = branches(chunks.as_ref());
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let root = branches.root();
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let proofs: Vec<_> = branches.map(|(proof, _)| proof).collect();
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assert_eq!(proofs.len() as u32, magnitude);
|
||||
for (i, proof) in proofs.into_iter().enumerate() {
|
||||
let encode = Encode::encode(&proof);
|
||||
let decode = Decode::decode(&mut &encode[..]).unwrap();
|
||||
assert_eq!(proof, decode);
|
||||
assert_eq!(encode, Encode::encode(&decode));
|
||||
|
||||
assert_eq!(branch_hash(&root, &proof, i).unwrap(), BlakeTwo256::hash(&chunks[i]));
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn roundtrip_proof_encoding() {
|
||||
for i in 2..16 {
|
||||
generate_trie_and_generate_proofs(i);
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user