Newer
Older
// Copyright 2019 Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
//! Gossip messages and the message validator
use substrate_network::consensus_gossip::{
self as network_gossip, ValidationResult as GossipValidationResult,
};
use polkadot_validation::SignedStatement;
use polkadot_primitives::{Block, Hash, SessionKey};
use codec::Decode;
use std::collections::HashMap;
use std::sync::Arc;
use parking_lot::RwLock;
use super::NetworkService;
/// The engine ID of the polkadot attestation system.
pub const POLKADOT_ENGINE_ID: sr_primitives::ConsensusEngineId = [b'd', b'o', b't', b'1'];
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
/// A gossip message.
#[derive(Encode, Decode, Clone)]
pub(crate) struct GossipMessage {
/// The relay chain parent hash.
pub(crate) relay_parent: Hash,
/// The signed statement being gossipped.
pub(crate) statement: SignedStatement,
}
/// whether a block is known.
pub enum Known {
/// The block is a known leaf.
Leaf,
/// The block is known to be old.
Old,
/// The block is known to be bad.
Bad,
}
/// An oracle for known blocks.
pub trait KnownOracle: Send + Sync {
/// whether a block is known. If it's not, returns `None`.
fn is_known(&self, block_hash: &Hash) -> Option<Known>;
}
impl<F> KnownOracle for F where F: Fn(&Hash) -> Option<Known> + Send + Sync {
fn is_known(&self, block_hash: &Hash) -> Option<Known> {
(self)(block_hash)
}
}
/// Register a gossip validator on the network service.
///
/// This returns a `RegisteredMessageValidator`
// NOTE: since RegisteredMessageValidator is meant to be a type-safe proof
// that we've actually done the registration, this should be the only way
// to construct it outside of tests.
pub fn register_validator<O: KnownOracle + 'static>(
service: &NetworkService,
oracle: O,
) -> RegisteredMessageValidator {
let validator = Arc::new(MessageValidator {
live_session: RwLock::new(HashMap::new()),
oracle,
});
let gossip_side = validator.clone();
service.with_gossip(|gossip, ctx|
gossip.register_validator(ctx, POLKADOT_ENGINE_ID, gossip_side)
);
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
RegisteredMessageValidator { inner: validator as _ }
}
/// A registered message validator.
///
/// Create this using `register_validator`.
#[derive(Clone)]
pub struct RegisteredMessageValidator {
inner: Arc<MessageValidator<KnownOracle>>,
}
impl RegisteredMessageValidator {
#[cfg(test)]
pub(crate) fn new_test<O: KnownOracle + 'static>(oracle: O) -> Self {
let validator = Arc::new(MessageValidator {
live_session: RwLock::new(HashMap::new()),
oracle,
});
RegisteredMessageValidator { inner: validator as _ }
}
/// Note a live attestation session. This must be removed later with
/// `remove_session`.
pub(crate) fn note_session(&self, relay_parent: Hash, validation: MessageValidationData) {
self.inner.live_session.write().insert(relay_parent, validation);
}
/// Remove a live attestation session when it is no longer live.
pub(crate) fn remove_session(&self, relay_parent: &Hash) {
self.inner.live_session.write().remove(relay_parent);
}
}
// data needed for validating gossip.
pub(crate) struct MessageValidationData {
/// The authorities at a block.
pub(crate) authorities: Vec<SessionKey>,
}
impl MessageValidationData {
fn check_statement(&self, relay_parent: &Hash, statement: &SignedStatement) -> bool {
self.authorities.contains(&statement.sender) &&
::polkadot_validation::check_statement(
&statement.statement,
&statement.signature,
relay_parent,
)
}
}
/// An unregistered message validator. Register this with `register_validator`.
pub struct MessageValidator<O: ?Sized> {
live_session: RwLock<HashMap<Hash, MessageValidationData>>,
oracle: O,
}
impl<O: KnownOracle + ?Sized> network_gossip::Validator<Block> for MessageValidator<O> {
fn validate(&self, context: &mut ValidatorContext<Block>, _sender: &PeerId, mut data: &[u8])
-> GossipValidationResult<Hash>
{
let orig_data = data;
match GossipMessage::decode(&mut data) {
Some(GossipMessage { relay_parent, statement }) => {
let live = self.live_session.read();
let topic = || ::router::attestation_topic(relay_parent.clone());
if let Some(validation) = live.get(&relay_parent) {
if validation.check_statement(&relay_parent, &statement) {
// repropagate
let topic = topic();
context.broadcast_message(topic, orig_data.to_owned(), false);
GossipValidationResult::ProcessAndKeep(topic)
}
} else {
match self.oracle.is_known(&relay_parent) {
None | Some(Known::Leaf) => GossipValidationResult::ProcessAndKeep(topic()),
Some(Known::Old) | Some(Known::Bad) => GossipValidationResult::Discard,
}
}
}
None => {
debug!(target: "validation", "Error decoding gossip message");