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// Copyright 2017 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/>.
//! Polkadot-specific network implementation.
//!
//! This manages gossip of consensus messages for BFT and for parachain statements,
//! parachain block and extrinsic data fetching, communication between collators and validators,
//! and more.
extern crate substrate_bft as bft;
extern crate substrate_codec as codec;
extern crate substrate_network;
extern crate substrate_primitives;
extern crate polkadot_api;
extern crate polkadot_consensus;
extern crate polkadot_primitives;
extern crate ed25519;
extern crate futures;
extern crate parking_lot;
extern crate tokio;
extern crate rhododendron;
#[macro_use]
extern crate log;
mod router;
pub mod consensus;
use codec::{Decode, Encode, Input, Output};
use futures::sync::oneshot;
use parking_lot::Mutex;
use polkadot_consensus::{Statement, SignedStatement, GenericStatement};
use polkadot_primitives::{AccountId, Block, SessionKey, Hash, Header};
use polkadot_primitives::parachain::{Id as ParaId, BlockData, Extrinsic, CandidateReceipt, Collation};
use substrate_network::{PeerId, RequestId, Context};
use substrate_network::consensus_gossip::ConsensusGossip;
use substrate_network::{message, generic_message};
use substrate_network::specialization::Specialization;
use substrate_network::StatusMessage as GenericFullStatus;
use self::collator_pool::{CollatorPool, Role, Action};
use std::collections::{HashMap, HashSet};
use std::sync::Arc;
#[cfg(test)]
mod tests;
/// Polkadot protocol id.
pub const DOT_PROTOCOL_ID: ::substrate_network::ProtocolId = *b"dot";
type FullStatus = GenericFullStatus<Block>;
/// Specialization of the network service for the polkadot protocol.
pub type NetworkService = ::substrate_network::Service<Block, PolkadotProtocol>;
/// Status of a Polkadot node.
#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Status {
collating_for: Option<(AccountId, ParaId)>,
}
impl Encode for Status {
fn encode_to<T: codec::Output>(&self, dest: &mut T) {
match self.collating_for {
Some(ref details) => {
}
None => {
}
}
}
impl Decode for Status {
fn decode<I: codec::Input>(input: &mut I) -> Option<Self> {
let collating_for = match input.read_byte()? {
0 => None,
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_ => return None,
};
Some(Status { collating_for })
}
}
struct BlockDataRequest {
attempted_peers: HashSet<SessionKey>,
consensus_parent: Hash,
candidate_hash: Hash,
block_data_hash: Hash,
sender: oneshot::Sender<BlockData>,
}
struct PeerInfo {
status: Status,
validator: bool,
session_keys: HashMap<Hash, SessionKey>,
}
#[derive(Default)]
struct KnowledgeEntry {
knows_block_data: Vec<SessionKey>,
knows_extrinsic: Vec<SessionKey>,
block_data: Option<BlockData>,
extrinsic: Option<Extrinsic>,
}
/// Tracks knowledge of peers.
struct Knowledge {
candidates: HashMap<Hash, KnowledgeEntry>,
}
impl Knowledge {
pub fn new() -> Self {
Knowledge {
candidates: HashMap::new(),
}
}
fn note_statement(&mut self, from: SessionKey, statement: &Statement) {
match *statement {
GenericStatement::Candidate(ref c) => {
let mut entry = self.candidates.entry(c.hash()).or_insert_with(Default::default);
entry.knows_block_data.push(from);
entry.knows_extrinsic.push(from);
}
GenericStatement::Available(ref hash) => {
let mut entry = self.candidates.entry(*hash).or_insert_with(Default::default);
entry.knows_block_data.push(from);
entry.knows_extrinsic.push(from);
}
GenericStatement::Valid(ref hash) | GenericStatement::Invalid(ref hash) => self.candidates.entry(*hash)
.or_insert_with(Default::default)
.knows_block_data
.push(from),
}
}
fn note_candidate(&mut self, hash: Hash, block_data: Option<BlockData>, extrinsic: Option<Extrinsic>) {
let entry = self.candidates.entry(hash).or_insert_with(Default::default);
entry.block_data = entry.block_data.take().or(block_data);
entry.extrinsic = entry.extrinsic.take().or(extrinsic);
}
}
struct CurrentConsensus {
knowledge: Arc<Mutex<Knowledge>>,
parent_hash: Hash,
session_keys: HashMap<SessionKey, PeerId>,
local_session_key: SessionKey,
}
impl CurrentConsensus {
// get locally stored block data for a candidate.
fn block_data(&self, hash: &Hash) -> Option<BlockData> {
self.knowledge.lock().candidates.get(hash)
.and_then(|entry| entry.block_data.clone())
}
fn peer_disconnected(&mut self, peer: &PeerInfo) {
if let Some(key) = peer.session_keys.get(&self.parent_hash) {
self.session_keys.remove(key);
}
}
}
/// Polkadot-specific messages.
pub enum Message {
/// signed statement and localized parent hash.
Statement(Hash, SignedStatement),
/// Tell the peer your session key for the current block.
// TODO: do this with a random challenge protocol
SessionKey(Hash, SessionKey),
/// Requesting parachain block data by candidate hash.
RequestBlockData(RequestId, Hash),
/// Provide block data by candidate hash or nothing if unknown.
BlockData(RequestId, Option<BlockData>),
/// Tell a collator their role.
CollatorRole(Role),
/// A collation provided by a peer. Relay parent and collation.
Collation(Hash, Collation),
}
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impl Encode for Message {
fn encode_to<T: Output>(&self, dest: &mut T) {
match *self {
Message::Statement(ref h, ref s) => {
dest.push_byte(0);
dest.push(h);
dest.push(s);
}
Message::SessionKey(ref h, ref k) => {
dest.push_byte(1);
dest.push(h);
dest.push(k);
}
Message::RequestBlockData(ref id, ref d) => {
dest.push_byte(2);
dest.push(id);
dest.push(d);
}
Message::BlockData(ref id, ref d) => {
dest.push_byte(3);
dest.push(id);
dest.push(d);
}
Message::CollatorRole(ref r) => {
dest.push_byte(4);
dest.push(r);
}
Message::Collation(ref h, ref c) => {
dest.push_byte(5);
dest.push(h);
dest.push(c);
}
}
}
}
impl Decode for Message {
fn decode<I: Input>(input: &mut I) -> Option<Self> {
match input.read_byte()? {
0 => Some(Message::Statement(Decode::decode(input)?, Decode::decode(input)?)),
1 => Some(Message::SessionKey(Decode::decode(input)?, Decode::decode(input)?)),
2 => Some(Message::RequestBlockData(Decode::decode(input)?, Decode::decode(input)?)),
3 => Some(Message::BlockData(Decode::decode(input)?, Decode::decode(input)?)),
4 => Some(Message::CollatorRole(Decode::decode(input)?)),
5 => Some(Message::Collation(Decode::decode(input)?, Decode::decode(input)?)),
_ => None,
}
}
}
fn send_polkadot_message(ctx: &mut Context<Block>, to: PeerId, message: Message) {
trace!(target: "p_net", "Sending polkadot message to {}: {:?}", to, message);
let encoded = message.encode();
ctx.send_message(to, generic_message::Message::ChainSpecific(encoded))
}
/// Polkadot protocol attachment for substrate.
pub struct PolkadotProtocol {
peers: HashMap<PeerId, PeerInfo>,
consensus_gossip: ConsensusGossip<Block>,
collators: CollatorPool,
live_consensus: Option<CurrentConsensus>,
in_flight: HashMap<(RequestId, PeerId), BlockDataRequest>,
pending: Vec<BlockDataRequest>,
next_req_id: u64,
}
impl Default for PolkadotProtocol {
fn default() -> Self {
Self::new()
}
}
impl PolkadotProtocol {
/// Instantiate a polkadot protocol handler.
pub fn new() -> Self {
PolkadotProtocol {
peers: HashMap::new(),
consensus_gossip: ConsensusGossip::new(),
collators: CollatorPool::new(),
live_consensus: None,
in_flight: HashMap::new(),
pending: Vec::new(),
next_req_id: 1,
}
}
/// Send a statement to a validator.
fn send_statement(&mut self, ctx: &mut Context<Block>, _val: SessionKey, parent_hash: Hash, statement: SignedStatement) {
// TODO: something more targeted than gossip.
let raw = Message::Statement(parent_hash, statement).encode();
self.consensus_gossip.multicast_chain_specific(ctx, raw, parent_hash);
}
/// Fetch block data by candidate receipt.
fn fetch_block_data(&mut self, ctx: &mut Context<Block>, candidate: &CandidateReceipt, relay_parent: Hash) -> oneshot::Receiver<BlockData> {
let (tx, rx) = oneshot::channel();
self.pending.push(BlockDataRequest {
attempted_peers: Default::default(),
consensus_parent: relay_parent,
candidate_hash: candidate.hash(),
block_data_hash: candidate.block_data_hash,
sender: tx,
});
self.dispatch_pending_requests(ctx);
rx
}
/// Note new consensus session.
fn new_consensus(&mut self, ctx: &mut Context<Block>, mut consensus: CurrentConsensus) {
let parent_hash = consensus.parent_hash;
let old_parent = self.live_consensus.as_ref().map(|c| c.parent_hash);
// TODO: optimize for when session key changes and only send to collators who are relevant in next few blocks.
for (id, info) in self.peers.iter_mut()
.filter(|&(_, ref info)| info.validator || info.status.collating_for.is_some())
{
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send_polkadot_message(
ctx,
*id,
Message::SessionKey(parent_hash, consensus.local_session_key)
);
if let Some(key) = info.session_keys.get(&parent_hash) {
consensus.session_keys.insert(*key, *id);
}
if let Some(ref old_parent) = old_parent {
info.session_keys.remove(old_parent);
}
}
self.live_consensus = Some(consensus);
self.consensus_gossip.collect_garbage(old_parent.as_ref());
}
fn dispatch_pending_requests(&mut self, ctx: &mut Context<Block>) {
let consensus = match self.live_consensus {
Some(ref mut c) => c,
None => {
self.pending.clear();
return;
}
};
let knowledge = consensus.knowledge.lock();
let mut new_pending = Vec::new();
for mut pending in ::std::mem::replace(&mut self.pending, Vec::new()) {
if pending.consensus_parent != consensus.parent_hash { continue }
if let Some(entry) = knowledge.candidates.get(&pending.candidate_hash) {
// answer locally
if let Some(ref data) = entry.block_data {
let _ = pending.sender.send(data.clone());
continue;
}
let next_peer = entry.knows_block_data.iter()
.filter_map(|x| consensus.session_keys.get(x).map(|id| (*x, *id)))
.find(|&(ref key, _)| pending.attempted_peers.insert(*key))
.map(|(_, id)| id);
// dispatch to peer
if let Some(peer_id) = next_peer {
let req_id = self.next_req_id;
self.next_req_id += 1;
send_polkadot_message(
ctx,
peer_id,
Message::RequestBlockData(req_id, pending.candidate_hash)
);
self.in_flight.insert((req_id, peer_id), pending);
continue;
}
}
new_pending.push(pending);
}
self.pending = new_pending;
}
fn on_polkadot_message(&mut self, ctx: &mut Context<Block>, peer_id: PeerId, raw: Vec<u8>, msg: Message) {
trace!(target: "p_net", "Polkadot message from {}: {:?}", peer_id, msg);
match msg {
Message::Statement(parent_hash, _statement) =>
self.consensus_gossip.on_chain_specific(ctx, peer_id, raw, parent_hash),
Message::SessionKey(parent_hash, key) => {
{
let info = match self.peers.get_mut(&peer_id) {
Some(peer) => peer,
None => return,
};
if !info.validator {
ctx.disable_peer(peer_id, "Unknown Polkadot-protocol reason");
return;
}
match self.live_consensus {
Some(ref mut consensus) if consensus.parent_hash == parent_hash => {
consensus.session_keys.insert(key, peer_id);
}
_ => {}
}
info.session_keys.insert(parent_hash, key);
}
self.dispatch_pending_requests(ctx);
}
Message::RequestBlockData(req_id, hash) => {
let block_data = self.live_consensus.as_ref()
.and_then(|c| c.block_data(&hash));
send_polkadot_message(ctx, peer_id, Message::BlockData(req_id, block_data));
}
Message::BlockData(req_id, data) => self.on_block_data(ctx, peer_id, req_id, data),
Message::Collation(relay_parent, collation) => self.on_collation(ctx, peer_id, relay_parent, collation),
Message::CollatorRole(_) => {},
}
}
fn on_block_data(&mut self, ctx: &mut Context<Block>, peer_id: PeerId, req_id: RequestId, data: Option<BlockData>) {
match self.in_flight.remove(&(req_id, peer_id)) {
Some(req) => {
if let Some(data) = data {
if data.hash() == req.block_data_hash {
let _ = req.sender.send(data);
return
}
}
self.pending.push(req);
self.dispatch_pending_requests(ctx);
}
None => ctx.disable_peer(peer_id, "Unknown Polkadot-protocol reason"),
}
}
}
impl Specialization<Block> for PolkadotProtocol {
fn status(&self) -> Vec<u8> {
Status { collating_for: None }.encode()
}
fn on_connect(&mut self, ctx: &mut Context<Block>, peer_id: PeerId, status: FullStatus) {
let local_status = match Status::decode(&mut &status.chain_status[..]) {
Some(status) => status,
None => {
}
};
if let Some((ref acc_id, ref para_id)) = local_status.collating_for {
if self.collator_peer_id(acc_id.clone()).is_some() {
ctx.disable_peer(peer_id, "Unknown Polkadot-protocol reason");
return
}
let collator_role = self.collators.on_new_collator(acc_id.clone(), para_id.clone());
send_polkadot_message(
ctx,
peer_id,
Message::CollatorRole(collator_role),
);
}
let validator = status.roles.contains(substrate_network::Roles::AUTHORITY);
let send_key = validator || local_status.collating_for.is_some();
self.peers.insert(peer_id, PeerInfo {
status: local_status,
session_keys: Default::default(),
validator,
});
self.consensus_gossip.new_peer(ctx, peer_id, status.roles);
if let (true, &Some(ref consensus)) = (send_key, &self.live_consensus) {
send_polkadot_message(
ctx,
peer_id,
Message::SessionKey(consensus.parent_hash, consensus.local_session_key)
);
}
self.dispatch_pending_requests(ctx);
}
fn on_disconnect(&mut self, ctx: &mut Context<Block>, peer_id: PeerId) {
if let Some(info) = self.peers.remove(&peer_id) {
if let Some((acc_id, _)) = info.status.collating_for {
let new_primary = self.collators.on_disconnect(acc_id)
.and_then(|new_primary| self.collator_peer_id(new_primary));
if let Some(new_primary) = new_primary {
send_polkadot_message(
ctx,
new_primary,
Message::CollatorRole(Role::Primary),
)
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}
}
if let (true, &mut Some(ref mut consensus)) = (info.validator, &mut self.live_consensus) {
consensus.peer_disconnected(&info);
}
{
let pending = &mut self.pending;
self.in_flight.retain(|&(_, ref peer), val| {
let retain = peer != &peer_id;
if !retain {
let (sender, _) = oneshot::channel();
pending.push(::std::mem::replace(val, BlockDataRequest {
attempted_peers: Default::default(),
consensus_parent: Default::default(),
candidate_hash: Default::default(),
block_data_hash: Default::default(),
sender,
}));
}
retain
});
}
self.consensus_gossip.peer_disconnected(ctx, peer_id);
self.dispatch_pending_requests(ctx);
}
}
fn on_message(&mut self, ctx: &mut Context<Block>, peer_id: PeerId, message: message::Message<Block>) {
match message {
generic_message::Message::BftMessage(msg) => {
trace!(target: "p_net", "Polkadot BFT message from {}: {:?}", peer_id, msg);
// TODO: check signature here? what if relevant block is unknown?
self.consensus_gossip.on_bft_message(ctx, peer_id, msg)
}
generic_message::Message::ChainSpecific(raw) => {
match Message::decode(&mut raw.as_slice()) {
Some(msg) => self.on_polkadot_message(ctx, peer_id, raw, msg),
None => {
trace!(target: "p_net", "Bad message from {}", peer_id);
ctx.disable_peer(peer_id, "Invalid polkadot protocol message format");
}
}
}
_ => {}
}
}
fn on_abort(&mut self) {
self.consensus_gossip.abort();
}
fn maintain_peers(&mut self, ctx: &mut Context<Block>) {
self.consensus_gossip.collect_garbage(None);
self.collators.collect_garbage(None);
self.dispatch_pending_requests(ctx);
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for collator_action in self.collators.maintain_peers() {
match collator_action {
Action::Disconnect(collator) => self.disconnect_bad_collator(ctx, collator),
Action::NewRole(account_id, role) => if let Some(collator) = self.collator_peer_id(account_id) {
send_polkadot_message(
ctx,
collator,
Message::CollatorRole(role),
)
},
}
}
}
fn on_block_imported(&mut self, _ctx: &mut Context<Block>, hash: Hash, _header: &Header) {
self.collators.collect_garbage(Some(&hash));
}
}
impl PolkadotProtocol {
// we received a collation from a peer
fn on_collation(&mut self, ctx: &mut Context<Block>, from: PeerId, relay_parent: Hash, collation: Collation) {
let collation_para = collation.receipt.parachain_index;
let collated_acc = collation.receipt.collator;
match self.peers.get(&from) {
None => ctx.disconnect_peer(from),
Some(peer_info) => match peer_info.status.collating_for {
None => ctx.disable_peer(from, "Unknown Polkadot-protocol reason"),
Some((ref acc_id, ref para_id)) => {
let structurally_valid = para_id == &collation_para && acc_id == &collated_acc;
if structurally_valid && collation.receipt.check_signature().is_ok() {
self.collators.on_collation(acc_id.clone(), relay_parent, collation)
} else {
ctx.disable_peer(from, "Unknown Polkadot-protocol reason")
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};
}
},
}
}
fn await_collation(&mut self, relay_parent: Hash, para_id: ParaId) -> oneshot::Receiver<Collation> {
let (tx, rx) = oneshot::channel();
self.collators.await_collation(relay_parent, para_id, tx);
rx
}
// get connected peer with given account ID for collation.
fn collator_peer_id(&self, account_id: AccountId) -> Option<PeerId> {
let check_info = |info: &PeerInfo| info
.status
.collating_for
.as_ref()
.map_or(false, |&(ref acc_id, _)| acc_id == &account_id);
self.peers
.iter()
.filter(|&(_, info)| check_info(info))
.map(|(peer_id, _)| *peer_id)
.next()
}
// disconnect a collator by account-id.
fn disconnect_bad_collator(&self, ctx: &mut Context<Block>, account_id: AccountId) {
if let Some(peer_id) = self.collator_peer_id(account_id) {
ctx.disable_peer(peer_id, "Unknown Polkadot-protocol reason")