From 8b0fa07204e5630471aca9d65d481727bfc65b71 Mon Sep 17 00:00:00 2001
From: Robert Habermeier <rphmeier@gmail.com>
Date: Sun, 19 Jan 2020 23:32:29 +0100
Subject: [PATCH 1/2] deprecate chain_status field of network handshake

---
 client/network/src/protocol.rs         |  2 +-
 client/network/src/protocol/message.rs | 58 +++++++++++++++++++++++++-
 2 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/client/network/src/protocol.rs b/client/network/src/protocol.rs
index 2aa29ea2793e3..6914ea9efe138 100644
--- a/client/network/src/protocol.rs
+++ b/client/network/src/protocol.rs
@@ -74,7 +74,7 @@ const MAX_KNOWN_BLOCKS: usize = 1024; // ~32kb per peer + LruHashSet overhead
 const MAX_KNOWN_EXTRINSICS: usize = 4096; // ~128kb per peer + overhead
 
 /// Current protocol version.
-pub(crate) const CURRENT_VERSION: u32 = 5;
+pub(crate) const CURRENT_VERSION: u32 = 6;
 /// Lowest version we support
 pub(crate) const MIN_VERSION: u32 = 3;
 
diff --git a/client/network/src/protocol/message.rs b/client/network/src/protocol/message.rs
index 30f0c34175aa5..4749cf38f801b 100644
--- a/client/network/src/protocol/message.rs
+++ b/client/network/src/protocol/message.rs
@@ -252,7 +252,29 @@ pub mod generic {
 	}
 
 	/// Status sent on connection.
+	// TODO https://github.com/paritytech/substrate/issues/4674: replace the `Status`
+	// struct with this one, after waiting a few releases beyond `NetworkSpecialization`'s
+	// removal (https://github.com/paritytech/substrate/pull/4665)
+	//
+	// and set MIN_VERSION to 6.
 	#[derive(Debug, PartialEq, Eq, Clone, Encode, Decode)]
+	pub struct CompactStatus<Hash, Number> {
+		/// Protocol version.
+		pub version: u32,
+		/// Minimum supported version.
+		pub min_supported_version: u32,
+		/// Supported roles.
+		pub roles: Roles,
+		/// Best block number.
+		pub best_number: Number,
+		/// Best block hash.
+		pub best_hash: Hash,
+		/// Genesis block hash.
+		pub genesis_hash: Hash,
+	}
+
+	/// Status sent on connection.
+	#[derive(Debug, PartialEq, Eq, Clone, Encode)]
 	pub struct Status<Hash, Number> {
 		/// Protocol version.
 		pub version: u32,
@@ -266,10 +288,44 @@ pub mod generic {
 		pub best_hash: Hash,
 		/// Genesis block hash.
 		pub genesis_hash: Hash,
-		/// Chain-specific status.
+		/// DEPRECATED. Chain-specific status.
 		pub chain_status: Vec<u8>,
 	}
 
+	impl<Hash: Decode, Number: Decode> Decode for Status<Hash, Number> {
+		fn decode<I: Input>(value: &mut I) -> Result<Self, codec::Error> {
+			const LAST_CHAIN_STATUS_VERSION: u32 = 5;
+			let compact = CompactStatus::decode(value)?;
+			let chain_status = match <Vec<u8>>::decode(value) {
+				Ok(v) => v,
+				Err(e)  => if compact.version <= LAST_CHAIN_STATUS_VERSION {
+					return Err(e)
+				} else {
+					Vec::new()
+				}
+			};
+
+			let CompactStatus {
+				version,
+				min_supported_version,
+				roles,
+				best_number,
+				best_hash,
+				genesis_hash,
+			} = compact;
+
+			Ok(Status {
+				version,
+				min_supported_version,
+				roles,
+				best_number,
+				best_hash,
+				genesis_hash,
+				chain_status,
+			})
+		}
+	}
+
 	/// Request block data from a peer.
 	#[derive(Debug, PartialEq, Eq, Clone, Encode, Decode)]
 	pub struct BlockRequest<Hash, Number> {

From 8e3886542de1e48a1f6b8824148686d3e41aaeb0 Mon Sep 17 00:00:00 2001
From: Robert Habermeier <rphmeier@gmail.com>
Date: Mon, 20 Jan 2020 12:41:42 +0100
Subject: [PATCH 2/2] Update client/network/src/protocol/message.rs

remove unneeded whitespace.

Co-Authored-By: Pierre Krieger <pierre.krieger1708@gmail.com>
---
 client/network/src/protocol/message.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/client/network/src/protocol/message.rs b/client/network/src/protocol/message.rs
index 4749cf38f801b..ef7d550de6cbe 100644
--- a/client/network/src/protocol/message.rs
+++ b/client/network/src/protocol/message.rs
@@ -298,7 +298,7 @@ pub mod generic {
 			let compact = CompactStatus::decode(value)?;
 			let chain_status = match <Vec<u8>>::decode(value) {
 				Ok(v) => v,
-				Err(e)  => if compact.version <= LAST_CHAIN_STATUS_VERSION {
+				Err(e) => if compact.version <= LAST_CHAIN_STATUS_VERSION {
 					return Err(e)
 				} else {
 					Vec::new()