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// This file is part of Substrate.
// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
// This program 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.
// This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
use sc_network_common::role::ObservedRole;
use sc_network_types::PeerId;
use sp_runtime::traits::Block as BlockT;
/// Validates consensus messages.
pub trait Validator<B: BlockT>: Send + Sync {
/// New peer is connected.
fn new_peer(&self, _context: &mut dyn ValidatorContext<B>, _who: &PeerId, _role: ObservedRole) {
}
/// New connection is dropped.
fn peer_disconnected(&self, _context: &mut dyn ValidatorContext<B>, _who: &PeerId) {}
/// Validate consensus message.
fn validate(
&self,
context: &mut dyn ValidatorContext<B>,
sender: &PeerId,
data: &[u8],
) -> ValidationResult<B::Hash>;
/// Produce a closure for validating messages on a given topic.
fn message_expired<'a>(&'a self) -> Box<dyn FnMut(B::Hash, &[u8]) -> bool + 'a> {
Box::new(move |_topic, _data| false)
}
/// Produce a closure for filtering egress messages.
fn message_allowed<'a>(
&'a self,
) -> Box<dyn FnMut(&PeerId, MessageIntent, &B::Hash, &[u8]) -> bool + 'a> {
Box::new(move |_who, _intent, _topic, _data| true)
}
}
/// Validation context. Allows reacting to incoming messages by sending out further messages.
pub trait ValidatorContext<B: BlockT> {
/// Broadcast all messages with given topic to peers that do not have it yet.
fn broadcast_topic(&mut self, topic: B::Hash, force: bool);
/// Broadcast a message to all peers that have not received it previously.
fn broadcast_message(&mut self, topic: B::Hash, message: Vec<u8>, force: bool);
/// Send addressed message to a peer.
fn send_message(&mut self, who: &PeerId, message: Vec<u8>);
/// Send all messages with given topic to a peer.
fn send_topic(&mut self, who: &PeerId, topic: B::Hash, force: bool);
}
/// The reason for sending out the message.
#[derive(Eq, PartialEq, Copy, Clone)]
#[cfg_attr(test, derive(Debug))]
pub enum MessageIntent {
/// Requested broadcast.
Broadcast,
/// Requested broadcast to all peers.
ForcedBroadcast,
/// Periodic rebroadcast of all messages to all peers.
PeriodicRebroadcast,
}
/// Message validation result.
pub enum ValidationResult<H> {
/// Message should be stored and propagated under given topic.
ProcessAndKeep(H),
/// Message should be processed, but not propagated.
ProcessAndDiscard(H),
/// Message should be ignored.
Discard,
}
/// A gossip message validator that discards all messages.
pub struct DiscardAll;
impl<B: BlockT> Validator<B> for DiscardAll {
fn validate(
&self,
_context: &mut dyn ValidatorContext<B>,
_sender: &PeerId,
_data: &[u8],
) -> ValidationResult<B::Hash> {
ValidationResult::Discard
}
fn message_expired<'a>(&'a self) -> Box<dyn FnMut(B::Hash, &[u8]) -> bool + 'a> {
Box::new(move |_topic, _data| true)
}
fn message_allowed<'a>(
&'a self,
) -> Box<dyn FnMut(&PeerId, MessageIntent, &B::Hash, &[u8]) -> bool + 'a> {
Box::new(move |_who, _intent, _topic, _data| false)
}
}