99 lines
2.9 KiB
Rust
99 lines
2.9 KiB
Rust
// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity 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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// Parity 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 Parity. If not, see <http://www.gnu.org/licenses/>.
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//! Epoch verifiers and transitions.
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use ethereum_types::H256;
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use rlp::{Encodable, Decodable, DecoderError, RlpStream, UntrustedRlp};
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/// A full epoch transition.
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#[derive(Debug, Clone)]
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pub struct Transition {
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/// Block hash at which the transition occurred.
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pub block_hash: H256,
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/// Block number at which the transition occurred.
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pub block_number: u64,
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/// "transition/epoch" proof from the engine combined with a finality proof.
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pub proof: Vec<u8>,
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}
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impl Encodable for Transition {
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fn rlp_append(&self, s: &mut RlpStream) {
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s.begin_list(3)
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.append(&self.block_hash)
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.append(&self.block_number)
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.append(&self.proof);
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}
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}
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impl Decodable for Transition {
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fn decode(rlp: &UntrustedRlp) -> Result<Self, DecoderError> {
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Ok(Transition {
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block_hash: rlp.val_at(0)?,
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block_number: rlp.val_at(1)?,
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proof: rlp.val_at(2)?,
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})
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}
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}
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/// An epoch transition pending a finality proof.
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/// Not all transitions need one.
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pub struct PendingTransition {
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/// "transition/epoch" proof from the engine.
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pub proof: Vec<u8>,
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}
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impl Encodable for PendingTransition {
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fn rlp_append(&self, s: &mut RlpStream) {
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s.append(&self.proof);
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}
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}
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impl Decodable for PendingTransition {
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fn decode(rlp: &UntrustedRlp) -> Result<Self, DecoderError> {
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Ok(PendingTransition {
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proof: rlp.as_val()?,
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})
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}
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}
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/// Verifier for all blocks within an epoch with self-contained state.
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pub trait EpochVerifier<M: ::parity_machine::Machine>: Send + Sync {
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/// Lightly verify the next block header.
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/// This may not be a header belonging to a different epoch.
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fn verify_light(&self, header: &M::Header) -> Result<(), M::Error>;
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/// Perform potentially heavier checks on the next block header.
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fn verify_heavy(&self, header: &M::Header) -> Result<(), M::Error> {
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self.verify_light(header)
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}
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/// Check a finality proof against this epoch verifier.
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/// Returns `Some(hashes)` if the proof proves finality of these hashes.
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/// Returns `None` if the proof doesn't prove anything.
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fn check_finality_proof(&self, _proof: &[u8]) -> Option<Vec<H256>> {
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None
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}
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}
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/// Special "no-op" verifier for stateless, epoch-less engines.
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pub struct NoOp;
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impl<M: ::parity_machine::Machine> EpochVerifier<M> for NoOp {
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fn verify_light(&self, _header: &M::Header) -> Result<(), M::Error> { Ok(()) }
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}
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