Port availability recovery to use req/res (#2694)

* add AvailableDataFetchingRequest

* rename AvailabilityFetchingRequest to ChunkFetchingRequest

* rename AvailabilityFetchingResponse to Chunk_

* add AvailableDataFetching request

* add available data fetching request to availability recovery message

* remove availability recovery message

* fix

* update network bridge

* port availability recovery to request/response

* use validators.len(), not shuffling

* fix availability recovery tests

* update guide

* Update node/network/availability-recovery/src/lib.rs

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>

* Update node/network/availability-recovery/src/lib.rs

Co-authored-by: Arkadiy Paronyan <arkady.paronyan@gmail.com>

* remove println

Co-authored-by: Bernhard Schuster <bernhard@ahoi.io>
Co-authored-by: Arkadiy Paronyan <arkady.paronyan@gmail.com>

polkadot/node/network/protocol/src/request_response/v1.rs

@@ -18,7 +18,10 @@
 
 use parity_scale_codec::{Decode, Encode};
 
-use polkadot_primitives::v1::{CandidateHash, CandidateReceipt, ErasureChunk, ValidatorIndex, CompressedPoV, Hash};
+use polkadot_primitives::v1::{
+	AvailableData, CandidateHash, CandidateReceipt, ErasureChunk, ValidatorIndex,
+	CompressedPoV, Hash,
+};
 use polkadot_primitives::v1::Id as ParaId;
 
 use super::request::IsRequest;
@@ -26,16 +29,16 @@ use super::Protocol;
 
 /// Request an availability chunk.
 #[derive(Debug, Copy, Clone, Encode, Decode)]
-pub struct AvailabilityFetchingRequest {
+pub struct ChunkFetchingRequest {
 	/// Hash of candidate we want a chunk for.
 	pub candidate_hash: CandidateHash,
 	/// The index of the chunk to fetch.
 	pub index: ValidatorIndex,
 }
 
-/// Receive a rqeuested erasure chunk.
+/// Receive a requested erasure chunk.
 #[derive(Debug, Clone, Encode, Decode)]
-pub enum AvailabilityFetchingResponse {
+pub enum ChunkFetchingResponse {
 	/// The requested chunk data.
 	#[codec(index = 0)]
 	Chunk(ChunkResponse),
@@ -44,10 +47,19 @@ pub enum AvailabilityFetchingResponse {
 	NoSuchChunk,
 }
 
+impl From<Option<ChunkResponse>> for ChunkFetchingResponse {
+	fn from(x: Option<ChunkResponse>) -> Self {
+		match x {
+			Some(c) => ChunkFetchingResponse::Chunk(c),
+			None => ChunkFetchingResponse::NoSuchChunk,
+		}
+	}
+}
+
 /// Skimmed down variant of `ErasureChunk`.
 ///
 /// Instead of transmitting a full `ErasureChunk` we transmit `ChunkResponse` in
-/// `AvailabilityFetchingResponse`, which omits the chunk's index. The index is already known by
+/// `ChunkFetchingResponse`, which omits the chunk's index. The index is already known by
 /// the requester and by not transmitting it, we ensure the requester is going to use his index
 /// value for validating the response, thus making sure he got what he requested.
 #[derive(Debug, Clone, Encode, Decode)]
@@ -66,7 +78,7 @@ impl From<ErasureChunk> for ChunkResponse {
 
 impl ChunkResponse {
 	/// Re-build an `ErasureChunk` from response and request.
-	pub fn recombine_into_chunk(self, req: &AvailabilityFetchingRequest) -> ErasureChunk {
+	pub fn recombine_into_chunk(self, req: &ChunkFetchingRequest) -> ErasureChunk {
 		ErasureChunk {
 			chunk: self.chunk,
 			proof: self.proof,
@@ -75,9 +87,9 @@ impl ChunkResponse {
 	}
 }
 
-impl IsRequest for AvailabilityFetchingRequest {
-	type Response = AvailabilityFetchingResponse;
-	const PROTOCOL: Protocol = Protocol::AvailabilityFetching;
+impl IsRequest for ChunkFetchingRequest {
+	type Response = ChunkFetchingResponse;
+	const PROTOCOL: Protocol = Protocol::ChunkFetching;
 }
 
 /// Request the advertised collation at that relay-parent.
@@ -101,3 +113,35 @@ impl IsRequest for CollationFetchingRequest {
 	type Response = CollationFetchingResponse;
 	const PROTOCOL: Protocol = Protocol::CollationFetching;
 }
+
+/// Request the entire available data for a candidate.
+#[derive(Debug, Clone, Encode, Decode)]
+pub struct AvailableDataFetchingRequest {
+	/// The candidate hash to get the available data for.
+	pub candidate_hash: CandidateHash,
+}
+
+/// Receive a requested available data.
+#[derive(Debug, Clone, Encode, Decode)]
+pub enum AvailableDataFetchingResponse {
+	/// The requested data.
+	#[codec(index = 0)]
+	AvailableData(AvailableData),
+	/// Node was not in possession of the requested data.
+	#[codec(index = 1)]
+	NoSuchData,
+}
+
+impl From<Option<AvailableData>> for AvailableDataFetchingResponse {
+	fn from(x: Option<AvailableData>) -> Self {
+		match x {
+			Some(data) => AvailableDataFetchingResponse::AvailableData(data),
+			None => AvailableDataFetchingResponse::NoSuchData,
+		}
+	}
+}
+
+impl IsRequest for AvailableDataFetchingRequest {
+	type Response = AvailableDataFetchingResponse;
+	const PROTOCOL: Protocol = Protocol::AvailableDataFetching;
+}