1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
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
85
86
87
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
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
// 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/>.

//! Abstract interfaces and data structures related to network sync.

pub mod message;
pub mod metrics;
pub mod warp;

use crate::{role::Roles, types::ReputationChange};
use futures::Stream;

use libp2p_identity::PeerId;

use message::{BlockAnnounce, BlockData, BlockRequest, BlockResponse};
use sc_consensus::{import_queue::RuntimeOrigin, IncomingBlock};
use sp_consensus::BlockOrigin;
use sp_runtime::{
	traits::{Block as BlockT, NumberFor},
	Justifications,
};
use warp::WarpSyncProgress;

use std::{any::Any, fmt, fmt::Formatter, pin::Pin, sync::Arc, task::Poll};

/// The sync status of a peer we are trying to sync with
#[derive(Debug)]
pub struct PeerInfo<Block: BlockT> {
	/// Their best block hash.
	pub best_hash: Block::Hash,
	/// Their best block number.
	pub best_number: NumberFor<Block>,
}

/// Info about a peer's known state (both full and light).
#[derive(Clone, Debug)]
pub struct ExtendedPeerInfo<B: BlockT> {
	/// Roles
	pub roles: Roles,
	/// Peer best block hash
	pub best_hash: B::Hash,
	/// Peer best block number
	pub best_number: NumberFor<B>,
}

/// Reported sync state.
#[derive(Clone, Eq, PartialEq, Debug)]
pub enum SyncState<BlockNumber> {
	/// Initial sync is complete, keep-up sync is active.
	Idle,
	/// Actively catching up with the chain.
	Downloading { target: BlockNumber },
	/// All blocks are downloaded and are being imported.
	Importing { target: BlockNumber },
}

impl<BlockNumber> SyncState<BlockNumber> {
	/// Are we actively catching up with the chain?
	pub fn is_major_syncing(&self) -> bool {
		!matches!(self, SyncState::Idle)
	}
}

/// Reported state download progress.
#[derive(Clone, Eq, PartialEq, Debug)]
pub struct StateDownloadProgress {
	/// Estimated download percentage.
	pub percentage: u32,
	/// Total state size in bytes downloaded so far.
	pub size: u64,
}

/// Syncing status and statistics.
#[derive(Debug, Clone)]
pub struct SyncStatus<Block: BlockT> {
	/// Current global sync state.
	pub state: SyncState<NumberFor<Block>>,
	/// Target sync block number.
	pub best_seen_block: Option<NumberFor<Block>>,
	/// Number of peers participating in syncing.
	pub num_peers: u32,
	/// Number of peers known to `SyncingEngine` (both full and light).
	pub num_connected_peers: u32,
	/// Number of blocks queued for import
	pub queued_blocks: u32,
	/// State sync status in progress, if any.
	pub state_sync: Option<StateDownloadProgress>,
	/// Warp sync in progress, if any.
	pub warp_sync: Option<WarpSyncProgress<Block>>,
}

/// A peer did not behave as expected and should be reported.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct BadPeer(pub PeerId, pub ReputationChange);

impl fmt::Display for BadPeer {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		write!(f, "Bad peer {}; Reputation change: {:?}", self.0, self.1)
	}
}

impl std::error::Error for BadPeer {}

/// Result of [`ChainSync::on_block_data`].
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum OnBlockData<Block: BlockT> {
	/// The block should be imported.
	Import(BlockOrigin, Vec<IncomingBlock<Block>>),
	/// A new block request needs to be made to the given peer.
	Request(PeerId, BlockRequest<Block>),
	/// Continue processing events.
	Continue,
}

/// Result of [`ChainSync::on_block_justification`].
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum OnBlockJustification<Block: BlockT> {
	/// The justification needs no further handling.
	Nothing,
	/// The justification should be imported.
	Import {
		peer: PeerId,
		hash: Block::Hash,
		number: NumberFor<Block>,
		justifications: Justifications,
	},
}

/// Result of `ChainSync::on_state_data`.
#[derive(Debug)]
pub enum OnStateData<Block: BlockT> {
	/// The block and state that should be imported.
	Import(BlockOrigin, IncomingBlock<Block>),
	/// A new state request needs to be made to the given peer.
	Continue,
}

/// Block or justification request polled from `ChainSync`
#[derive(Debug)]
pub enum ImportResult<B: BlockT> {
	BlockImport(BlockOrigin, Vec<IncomingBlock<B>>),
	JustificationImport(RuntimeOrigin, B::Hash, NumberFor<B>, Justifications),
}

/// Value polled from `ChainSync`
#[derive(Debug)]
pub enum PollResult<B: BlockT> {
	Import(ImportResult<B>),
	Announce(PollBlockAnnounceValidation<B::Header>),
}

/// Result of [`ChainSync::poll_block_announce_validation`].
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum PollBlockAnnounceValidation<H> {
	/// The announcement failed at validation.
	///
	/// The peer reputation should be decreased.
	Failure {
		/// Who sent the processed block announcement?
		who: PeerId,
		/// Should the peer be disconnected?
		disconnect: bool,
	},
	/// The announcement does not require further handling.
	Nothing {
		/// Who sent the processed block announcement?
		who: PeerId,
		/// Was this their new best block?
		is_best: bool,
		/// The announcement.
		announce: BlockAnnounce<H>,
	},
	/// The block announcement should be skipped.
	Skip,
}

/// Sync operation mode.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum SyncMode {
	/// Full block download and verification.
	Full,
	/// Download blocks and the latest state.
	LightState {
		/// Skip state proof download and verification.
		skip_proofs: bool,
		/// Download indexed transactions for recent blocks.
		storage_chain_mode: bool,
	},
	/// Warp sync - verify authority set transitions and the latest state.
	Warp,
}

impl SyncMode {
	/// Returns `true` if `self` is [`Self::Warp`].
	pub fn is_warp(&self) -> bool {
		matches!(self, Self::Warp)
	}

	/// Returns `true` if `self` is [`Self::LightState`].
	pub fn light_state(&self) -> bool {
		matches!(self, Self::LightState { .. })
	}
}

impl Default for SyncMode {
	fn default() -> Self {
		Self::Full
	}
}
#[derive(Debug)]
pub struct Metrics {
	pub queued_blocks: u32,
	pub fork_targets: u32,
	pub justifications: metrics::Metrics,
}

#[derive(Debug)]
pub enum PeerRequest<B: BlockT> {
	Block(BlockRequest<B>),
	State,
	WarpProof,
}

/// Wrapper for implementation-specific state request.
///
/// NOTE: Implementation must be able to encode and decode it for network purposes.
pub struct OpaqueStateRequest(pub Box<dyn Any + Send>);

impl fmt::Debug for OpaqueStateRequest {
	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
		f.debug_struct("OpaqueStateRequest").finish()
	}
}

/// Wrapper for implementation-specific state response.
///
/// NOTE: Implementation must be able to encode and decode it for network purposes.
pub struct OpaqueStateResponse(pub Box<dyn Any + Send>);

impl fmt::Debug for OpaqueStateResponse {
	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
		f.debug_struct("OpaqueStateResponse").finish()
	}
}

/// Wrapper for implementation-specific block request.
///
/// NOTE: Implementation must be able to encode and decode it for network purposes.
pub struct OpaqueBlockRequest(pub Box<dyn Any + Send>);

impl fmt::Debug for OpaqueBlockRequest {
	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
		f.debug_struct("OpaqueBlockRequest").finish()
	}
}

/// Wrapper for implementation-specific block response.
///
/// NOTE: Implementation must be able to encode and decode it for network purposes.
pub struct OpaqueBlockResponse(pub Box<dyn Any + Send>);

impl fmt::Debug for OpaqueBlockResponse {
	fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
		f.debug_struct("OpaqueBlockResponse").finish()
	}
}

/// Provides high-level status of syncing.
#[async_trait::async_trait]
pub trait SyncStatusProvider<Block: BlockT>: Send + Sync {
	/// Get high-level view of the syncing status.
	async fn status(&self) -> Result<SyncStatus<Block>, ()>;
}

#[async_trait::async_trait]
impl<T, Block> SyncStatusProvider<Block> for Arc<T>
where
	T: ?Sized,
	T: SyncStatusProvider<Block>,
	Block: BlockT,
{
	async fn status(&self) -> Result<SyncStatus<Block>, ()> {
		T::status(self).await
	}
}

/// Syncing-related events that other protocols can subscribe to.
pub enum SyncEvent {
	/// Peer that the syncing implementation is tracking connected.
	PeerConnected(PeerId),

	/// Peer that the syncing implementation was tracking disconnected.
	PeerDisconnected(PeerId),
}

pub trait SyncEventStream: Send + Sync {
	/// Subscribe to syncing-related events.
	fn event_stream(&self, name: &'static str) -> Pin<Box<dyn Stream<Item = SyncEvent> + Send>>;
}

impl<T> SyncEventStream for Arc<T>
where
	T: ?Sized,
	T: SyncEventStream,
{
	fn event_stream(&self, name: &'static str) -> Pin<Box<dyn Stream<Item = SyncEvent> + Send>> {
		T::event_stream(self, name)
	}
}

/// Something that represents the syncing strategy to download past and future blocks of the chain.
pub trait ChainSync<Block: BlockT>: Send {
	/// Returns the state of the sync of the given peer.
	///
	/// Returns `None` if the peer is unknown.
	fn peer_info(&self, who: &PeerId) -> Option<PeerInfo<Block>>;

	/// Returns the current sync status.
	fn status(&self) -> SyncStatus<Block>;

	/// Number of active forks requests. This includes
	/// requests that are pending or could be issued right away.
	fn num_sync_requests(&self) -> usize;

	/// Number of downloaded blocks.
	fn num_downloaded_blocks(&self) -> usize;

	/// Returns the current number of peers stored within this state machine.
	fn num_peers(&self) -> usize;

	/// Returns the number of peers we're connected to and that are being queried.
	fn num_active_peers(&self) -> usize;

	/// Handle a new connected peer.
	///
	/// Call this method whenever we connect to a new peer.
	fn new_peer(
		&mut self,
		who: PeerId,
		best_hash: Block::Hash,
		best_number: NumberFor<Block>,
	) -> Result<Option<BlockRequest<Block>>, BadPeer>;

	/// Signal that a new best block has been imported.
	fn update_chain_info(&mut self, best_hash: &Block::Hash, best_number: NumberFor<Block>);

	/// Schedule a justification request for the given block.
	fn request_justification(&mut self, hash: &Block::Hash, number: NumberFor<Block>);

	/// Clear all pending justification requests.
	fn clear_justification_requests(&mut self);

	/// Request syncing for the given block from given set of peers.
	fn set_sync_fork_request(
		&mut self,
		peers: Vec<PeerId>,
		hash: &Block::Hash,
		number: NumberFor<Block>,
	);

	/// Handle a response from the remote to a block request that we made.
	///
	/// `request` must be the original request that triggered `response`.
	/// or `None` if data comes from the block announcement.
	///
	/// If this corresponds to a valid block, this outputs the block that
	/// must be imported in the import queue.
	fn on_block_data(
		&mut self,
		who: &PeerId,
		request: Option<BlockRequest<Block>>,
		response: BlockResponse<Block>,
	) -> Result<OnBlockData<Block>, BadPeer>;

	/// Handle a response from the remote to a justification request that we made.
	///
	/// `request` must be the original request that triggered `response`.
	fn on_block_justification(
		&mut self,
		who: PeerId,
		response: BlockResponse<Block>,
	) -> Result<OnBlockJustification<Block>, BadPeer>;

	/// Call this when a justification has been processed by the import queue,
	/// with or without errors.
	fn on_justification_import(
		&mut self,
		hash: Block::Hash,
		number: NumberFor<Block>,
		success: bool,
	);

	/// Notify about finalization of the given block.
	fn on_block_finalized(&mut self, hash: &Block::Hash, number: NumberFor<Block>);

	/// Push a block announce validation.
	///
	/// It is required that [`ChainSync::poll_block_announce_validation`] is called
	/// to check for finished block announce validations.
	fn push_block_announce_validation(
		&mut self,
		who: PeerId,
		hash: Block::Hash,
		announce: BlockAnnounce<Block::Header>,
		is_best: bool,
	);

	/// Poll block announce validation.
	///
	/// Block announce validations can be pushed by using
	/// [`ChainSync::push_block_announce_validation`].
	///
	/// This should be polled until it returns [`Poll::Pending`].
	fn poll_block_announce_validation(
		&mut self,
		cx: &mut std::task::Context<'_>,
	) -> Poll<PollBlockAnnounceValidation<Block::Header>>;

	/// Call when a peer has disconnected.
	/// Canceled obsolete block request may result in some blocks being ready for
	/// import, so this functions checks for such blocks and returns them.
	fn peer_disconnected(&mut self, who: &PeerId);

	/// Return some key metrics.
	fn metrics(&self) -> Metrics;

	/// Access blocks from implementation-specific block response.
	fn block_response_into_blocks(
		&self,
		request: &BlockRequest<Block>,
		response: OpaqueBlockResponse,
	) -> Result<Vec<BlockData<Block>>, String>;

	/// Advance the state of `ChainSync`
	///
	/// Internally calls [`ChainSync::poll_block_announce_validation()`] and
	/// this function should be polled until it returns [`Poll::Pending`] to
	/// consume all pending events.
	fn poll(
		&mut self,
		cx: &mut std::task::Context,
	) -> Poll<PollBlockAnnounceValidation<Block::Header>>;

	/// Send block request to peer
	fn send_block_request(&mut self, who: PeerId, request: BlockRequest<Block>);
}