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use std::collections::HashMap;
use crate::challenge::PartialState;
use crate::sharding::{ChunkHash, ReceiptProof, ShardChunkHeader};
use crate::transaction::SignedTransaction;
use borsh::{BorshDeserialize, BorshSerialize};
use unc_crypto::Signature;
use unc_primitives_core::hash::CryptoHash;
use unc_primitives_core::types::AccountId;
/// The state witness for a chunk; proves the state transition that the
/// chunk attests to.
#[derive(Debug, Clone, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
pub struct ChunkStateWitness {
/// The chunk header that this witness is for. While this is not needed
/// to apply the state transition, it is needed for a chunk validator to
/// produce a chunk endorsement while knowing what they are endorsing.
pub chunk_header: ShardChunkHeader,
/// The base state and post-state-root of the main transition where we
/// apply transactions and receipts. Corresponds to the state transition
/// that takes us from the pre-state-root of the last new chunk of this
/// shard to the post-state-root of that same chunk.
pub main_state_transition: ChunkStateTransition,
/// For the main state transition, we apply transactions and receipts.
/// Exactly which of them must be applied is a deterministic property
/// based on the blockchain history this chunk is based on.
///
/// The set of receipts is exactly
/// Filter(R, |receipt| receipt.target_shard = S), where
/// - R is the set of outgoing receipts included in the set of chunks C
/// (defined below),
/// - S is the shard of this chunk.
///
/// The set of chunks C, from which the receipts are sourced, is defined as
/// all new chunks included in the set of blocks B.
///
/// The set of blocks B is defined as the contiguous subsequence of blocks
/// B1 (EXCLUSIVE) to B2 (inclusive) in this chunk's chain (i.e. the linear
/// chain that this chunk's parent block is on), where B1 is the block that
/// contains the last new chunk of shard S before this chunk, and B1 is the
/// block that contains the last new chunk of shard S before B2.
///
/// Furthermore, the set of transactions to apply is exactly the
/// transactions included in the chunk of shard S at B2.
///
/// For the purpose of this text, a "new chunk" is defined as a chunk that
/// is proposed by a chunk producer, not one that was copied from the
/// previous block (commonly called a "missing chunk").
///
/// This field, `source_receipt_proofs`, is a (non-strict) superset of the
/// receipts that must be applied, along with information that allows these
/// receipts to be verifiable against the blockchain history.
pub source_receipt_proofs: HashMap<ChunkHash, ReceiptProof>,
/// An overall hash of the list of receipts that should be applied. This is
/// redundant information but is useful for diagnosing why a witness might
/// fail. This is the hash of the borsh encoding of the Vec<Receipt> in the
/// order that they should be applied.
pub exact_receipts_hash: CryptoHash,
/// The transactions to apply. These must be in the correct order in which
/// they are to be applied.
pub transactions: Vec<SignedTransaction>,
/// For each missing chunk after the last new chunk of the shard, we need
/// to carry out an implicit state transition. Mostly, this is for
/// distributing validator rewards. This list contains one for each such
/// chunk, in forward chronological order.
///
/// After these are applied as well, we should arrive at the pre-state-root
/// of the chunk that this witness is for.
pub implicit_transitions: Vec<ChunkStateTransition>,
/// Finally, we need to be able to verify that the new transitions proposed
/// by the chunk (that this witness is for) are valid. For that, we need
/// the transactions as well as another partial storage (based on the
/// pre-state-root of this chunk) in order to verify that the sender
/// accounts have appropriate balances, access keys, nonces, etc.
pub new_transactions: Vec<SignedTransaction>,
pub new_transactions_validation_state: PartialState,
}
/// Represents the base state and the expected post-state-root of a chunk's state
/// transition. The actual state transition itself is not included here.
#[derive(Debug, Clone, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
pub struct ChunkStateTransition {
/// The block that contains the chunk; this identifies which part of the
/// state transition we're talking about.
pub block_hash: CryptoHash,
/// The partial state before the state transition. This includes whatever
/// initial state that is necessary to compute the state transition for this
/// chunk.
pub base_state: PartialState,
/// The expected final state root after applying the state transition.
/// This is redundant information, because the post state root can be
/// derived by applying the state transition onto the base state, but
/// this makes it easier to debug why a state witness may fail to validate.
pub post_state_root: CryptoHash,
}
/// The endorsement of a chunk by a chunk validator. By providing this, a
/// chunk validator has verified that the chunk state witness is correct.
#[derive(Debug, Clone, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
pub struct ChunkEndorsement {
pub inner: ChunkEndorsementInner,
pub account_id: AccountId,
pub signature: Signature,
}
/// This is the part of the chunk endorsement that is actually being signed.
#[derive(Debug, Clone, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
pub struct ChunkEndorsementInner {
pub chunk_hash: ChunkHash,
/// An arbitrary static string to make sure that this struct cannot be
/// serialized to look identical to another serialized struct. For chunk
/// production we are signing a chunk hash, so we need to make sure that
/// this signature means something different.
///
signature_differentiator: String,
}
impl ChunkEndorsementInner {
pub fn new(chunk_hash: ChunkHash) -> Self {
Self { chunk_hash, signature_differentiator: "ChunkEndorsement".to_owned() }
}
}
/// Stored on disk for each chunk, including missing chunks, in order to
/// produce a chunk state witness when needed.
#[derive(Debug, Clone, PartialEq, Eq, BorshSerialize, BorshDeserialize)]
pub struct StoredChunkStateTransitionData {
/// The partial state that is needed to apply the state transition,
/// whether it is a new chunk state transition or a implicit missing chunk
/// state transition.
pub base_state: PartialState,
/// If this is a new chunk state transition, the hash of the receipts that
/// were used to apply the state transition. This is redundant information,
/// but is used to validate against `StateChunkWitness::exact_receipts_hash`
/// to ease debugging of why a state witness may be incorrect.
pub receipts_hash: CryptoHash,
}