les: make peer buffer flow params optional

ethcore/light/src/net/error.rs

@@ -56,6 +56,8 @@ pub enum Error {
 	UnknownPeer,
 	/// Unsolicited response.
 	UnsolicitedResponse,
+	/// Not a server.
+	NotServer,
 }
 
 impl Error {
@@ -70,6 +72,7 @@ impl Error {
 			Error::WrongNetwork => Punishment::Disable,
 			Error::UnknownPeer => Punishment::Disconnect,
 			Error::UnsolicitedResponse => Punishment::Disable,
+			Error::NotServer => Punishment::Disable,
 		}
 	}
 }
@@ -97,6 +100,7 @@ impl fmt::Display for Error {
 			Error::WrongNetwork => write!(f, "Wrong network"),
 			Error::UnknownPeer => write!(f, "Unknown peer"),
 			Error::UnsolicitedResponse => write!(f, "Peer provided unsolicited data"),
+			Error::NotServer => write!(f, "Peer not a server."),
 		}
 	}
 }

ethcore/light/src/net/mod.rs

@@ -116,10 +116,9 @@ struct PendingPeer {
 // data about each peer.
 struct Peer {
 	local_buffer: Buffer, // their buffer relative to us
-	remote_buffer: Buffer, // our buffer relative to them
 	status: Status,
 	capabilities: Capabilities,
-	remote_flow: FlowParams,
+	remote_flow: Option<(Buffer, FlowParams)>,
 	sent_head: H256, // last head we've given them.
 	last_update: SteadyTime,
 }
@@ -142,12 +141,6 @@ impl Peer {
 
 		self.local_buffer.current()
 	}
-
-	// recharge remote buffer with remote flow params.
-	fn recharge_remote(&mut self) {
-		let flow = &mut self.remote_flow;
-		flow.recharge(&mut self.remote_buffer);
-	}
 }
 
 /// An LES event handler.
@@ -250,16 +243,21 @@ impl LightProtocol {
 	/// Check the maximum amount of requests of a specific type 
 	/// which a peer would be able to serve.
 	pub fn max_requests(&self, peer: PeerId, kind: request::Kind) -> Option<usize> {
-		self.peers.read().get(&peer).map(|peer| {
+		self.peers.read().get(&peer).and_then(|peer| {
 			let mut peer = peer.lock();
-			peer.recharge_remote();
+			match peer.remote_flow.as_mut() {
-			peer.remote_flow.max_amount(&peer.remote_buffer, kind)
+				Some(&mut (ref mut buf, ref flow)) => {
+					flow.recharge(buf);
+					Some(flow.max_amount(&*buf, kind))
+				}
+				None => None,
+			}
 		})
 	}
 
 	/// Make a request to a peer. 
 	///
-	/// Fails on: nonexistent peer, network error,
+	/// Fails on: nonexistent peer, network error, peer not server,
 	/// insufficient buffer. Does not check capabilities before sending.
 	/// On success, returns a request id which can later be coordinated 
 	/// with an event.
@@ -268,10 +266,14 @@ impl LightProtocol {
 		let peer = try!(peers.get(peer_id).ok_or_else(|| Error::UnknownPeer));
 		let mut peer = peer.lock();
 
-		peer.recharge_remote();
+		match peer.remote_flow.as_mut() {
-
+			Some(&mut (ref mut buf, ref flow)) => {
-		let max = peer.remote_flow.compute_cost(request.kind(), request.amount());
+				flow.recharge(buf);
-		try!(peer.remote_buffer.deduct_cost(max));
+				let max = flow.compute_cost(request.kind(), request.amount());
+				try!(buf.deduct_cost(max));
+			}
+			None => return Err(Error::NotServer),
+		}
 
 		let req_id = self.req_id.fetch_add(1, Ordering::SeqCst);
 		let packet_data = encode_request(&request, req_id);
@@ -390,8 +392,13 @@ impl LightProtocol {
 		match peers.get(peer) {
 			Some(peer_info) => {
 				let mut peer_info = peer_info.lock();
-				let actual_buffer = ::std::cmp::min(cur_buffer, *peer_info.remote_flow.limit());
+				match peer_info.remote_flow.as_mut() {
-				peer_info.remote_buffer.update_to(actual_buffer);
+					Some(&mut (ref mut buf, ref mut flow)) => {
+						let actual_buffer = ::std::cmp::min(cur_buffer, *flow.limit());				
+						buf.update_to(actual_buffer)
+					}
+					None => return Err(Error::NotServer), // this really should be impossible.
+				}
 				Ok(ReqId(req_id))
 			}
 			None => Err(Error::UnknownPeer), // probably only occurs in a race of some kind.
@@ -516,7 +523,7 @@ impl LightProtocol {
 		};
 
 		let capabilities = self.capabilities.read().clone();
-		let status_packet = status::write_handshake(&status, &capabilities, &self.flow_params);
+		let status_packet = status::write_handshake(&status, &capabilities, Some(&self.flow_params));
 
 		io.send(peer, packet::STATUS, status_packet);
 
@@ -543,12 +550,13 @@ impl LightProtocol {
 			return Err(Error::WrongNetwork);
 		}
 
+		let remote_flow = flow_params.map(|params| (params.create_buffer(), params));
+
 		self.peers.write().insert(*peer, Mutex::new(Peer {
 			local_buffer: self.flow_params.create_buffer(),
-			remote_buffer: flow_params.create_buffer(),
 			status: status.clone(),
 			capabilities: capabilities.clone(),
-			remote_flow: flow_params,
+			remote_flow: remote_flow,
 			sent_head: pending.sent_head,
 			last_update: pending.last_update,
 		}));

ethcore/light/src/net/status.rs

@@ -198,7 +198,7 @@ impl Capabilities {
 ///   - chain status
 ///   - serving capabilities
 ///   - buffer flow parameters
-pub fn parse_handshake(rlp: UntrustedRlp) -> Result<(Status, Capabilities, FlowParams), DecoderError> {
+pub fn parse_handshake(rlp: UntrustedRlp) -> Result<(Status, Capabilities, Option<FlowParams>), DecoderError> {
 	let mut parser = Parser {
 		pos: 0,
 		rlp: rlp,
@@ -221,17 +221,20 @@ pub fn parse_handshake(rlp: UntrustedRlp) -> Result<(Status, Capabilities, FlowP
 		tx_relay: parser.expect_raw(Key::TxRelay).is_ok(),
 	};
 
-	let flow_params = FlowParams::new(
+	let flow_params = match (
-		try!(parser.expect(Key::BufferLimit)),
+		parser.expect(Key::BufferLimit),
-		try!(parser.expect(Key::BufferCostTable)),
+		parser.expect(Key::BufferCostTable),
-		try!(parser.expect(Key::BufferRechargeRate)),
+		parser.expect(Key::BufferRechargeRate)
-	);
+	) {
+		(Ok(bl), Ok(bct), Ok(brr)) => Some(FlowParams::new(bl, bct, brr)),
+		_ => None,
+	};
 
 	Ok((status, capabilities, flow_params))
 }
 
 /// Write a handshake, given status, capabilities, and flow parameters.
-pub fn write_handshake(status: &Status, capabilities: &Capabilities, flow_params: &FlowParams) -> Vec<u8> {
+pub fn write_handshake(status: &Status, capabilities: &Capabilities, flow_params: Option<&FlowParams>) -> Vec<u8> {
 	let mut pairs = Vec::new();
 	pairs.push(encode_pair(Key::ProtocolVersion, &status.protocol_version));
 	pairs.push(encode_pair(Key::NetworkId, &(status.network_id as u64)));
@@ -253,9 +256,11 @@ pub fn write_handshake(status: &Status, capabilities: &Capabilities, flow_params
 		pairs.push(encode_flag(Key::TxRelay));
 	}
 
-	pairs.push(encode_pair(Key::BufferLimit, flow_params.limit()));
+	if let Some(flow_params) = flow_params {
-	pairs.push(encode_pair(Key::BufferCostTable, flow_params.cost_table()));
+		pairs.push(encode_pair(Key::BufferLimit, flow_params.limit()));
-	pairs.push(encode_pair(Key::BufferRechargeRate, flow_params.recharge_rate()));
+		pairs.push(encode_pair(Key::BufferCostTable, flow_params.cost_table()));
+		pairs.push(encode_pair(Key::BufferRechargeRate, flow_params.recharge_rate()));
+	}
 
 	let mut stream = RlpStream::new_list(pairs.len());
 
@@ -386,14 +391,14 @@ mod tests {
 			1000.into(),
 		);
 
-		let handshake = write_handshake(&status, &capabilities, &flow_params);
+		let handshake = write_handshake(&status, &capabilities, Some(&flow_params));
 
 		let (read_status, read_capabilities, read_flow)
 			= parse_handshake(UntrustedRlp::new(&handshake)).unwrap();
 
 		assert_eq!(read_status, status);
 		assert_eq!(read_capabilities, capabilities);
-		assert_eq!(read_flow, flow_params);
+		assert_eq!(read_flow.unwrap(), flow_params);
 	}
 
 	#[test]
@@ -421,14 +426,14 @@ mod tests {
 			1000.into(),
 		);
 
-		let handshake = write_handshake(&status, &capabilities, &flow_params);
+		let handshake = write_handshake(&status, &capabilities, Some(&flow_params));
 
 		let (read_status, read_capabilities, read_flow)
 			= parse_handshake(UntrustedRlp::new(&handshake)).unwrap();
 
 		assert_eq!(read_status, status);
 		assert_eq!(read_capabilities, capabilities);
-		assert_eq!(read_flow, flow_params);
+		assert_eq!(read_flow.unwrap(), flow_params);
 	}
 
 	#[test]
@@ -456,7 +461,7 @@ mod tests {
 			1000.into(),
 		);
 
-		let handshake = write_handshake(&status, &capabilities, &flow_params);
+		let handshake = write_handshake(&status, &capabilities, Some(&flow_params));
 		let interleaved = {
 			let handshake = UntrustedRlp::new(&handshake);
 			let mut stream = RlpStream::new_list(handshake.item_count() * 3);
@@ -478,7 +483,7 @@ mod tests {
 
 		assert_eq!(read_status, status);
 		assert_eq!(read_capabilities, capabilities);
-		assert_eq!(read_flow, flow_params);
+		assert_eq!(read_flow.unwrap(), flow_params);
 	}
 
 	#[test]
@@ -528,4 +533,33 @@ mod tests {
 		let out = stream.drain();
 		assert!(parse_announcement(UntrustedRlp::new(&out)).is_ok());
 	}
+
+	#[test]
+	fn optional_flow() {
+		let status = Status {
+			protocol_version: 1,
+			network_id: 1,
+			head_td: U256::default(),
+			head_hash: H256::default(),
+			head_num: 10,
+			genesis_hash: H256::zero(),
+			last_head: None,
+		};
+
+		let capabilities = Capabilities {
+			serve_headers: true,
+			serve_chain_since: Some(5),
+			serve_state_since: Some(8),
+			tx_relay: true,
+		};
+
+		let handshake = write_handshake(&status, &capabilities, None);
+
+		let (read_status, read_capabilities, read_flow)
+			= parse_handshake(UntrustedRlp::new(&handshake)).unwrap();
+
+		assert_eq!(read_status, status);
+		assert_eq!(read_capabilities, capabilities);
+		assert!(read_flow.is_none());
+	}
 }

ethcore/light/src/net/tests/mod.rs

@@ -204,7 +204,7 @@ fn handshake_expected() {
 
 	let status = status(provider.client.chain_info());
 
-	let packet_body = write_handshake(&status, &capabilities, &flow_params);
+	let packet_body = write_handshake(&status, &capabilities, Some(&flow_params));
 
 	proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));
 }
@@ -220,7 +220,7 @@ fn genesis_mismatch() {
 	let mut status = status(provider.client.chain_info());
 	status.genesis_hash = H256::default();
 
-	let packet_body = write_handshake(&status, &capabilities, &flow_params);
+	let packet_body = write_handshake(&status, &capabilities, Some(&flow_params));
 
 	proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));
 }
@@ -235,12 +235,12 @@ fn buffer_overflow() {
 	let status = status(provider.client.chain_info());
 
 	{
-		let packet_body = write_handshake(&status, &capabilities, &flow_params);	
+		let packet_body = write_handshake(&status, &capabilities, Some(&flow_params));	
 		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
 	}
 
 	{
-		let my_status = write_handshake(&status, &capabilities, &flow_params);
+		let my_status = write_handshake(&status, &capabilities, Some(&flow_params));
 		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
 	}
 
@@ -267,14 +267,14 @@ fn get_block_headers() {
 	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
 
 	let cur_status = status(provider.client.chain_info());
-	let my_status = write_handshake(&cur_status, &capabilities, &flow_params);
+	let my_status = write_handshake(&cur_status, &capabilities, Some(&flow_params));
 
 	provider.client.add_blocks(100, EachBlockWith::Nothing);
 
 	let cur_status = status(provider.client.chain_info());
 
 	{
-		let packet_body = write_handshake(&cur_status, &capabilities, &flow_params);	
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
 		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
 		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
 	}
@@ -317,14 +317,14 @@ fn get_block_bodies() {
 	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
 
 	let cur_status = status(provider.client.chain_info());
-	let my_status = write_handshake(&cur_status, &capabilities, &flow_params);
+	let my_status = write_handshake(&cur_status, &capabilities, Some(&flow_params));
 
 	provider.client.add_blocks(100, EachBlockWith::Nothing);
 
 	let cur_status = status(provider.client.chain_info());
 
 	{
-		let packet_body = write_handshake(&cur_status, &capabilities, &flow_params);	
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
 		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
 		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
 	}
@@ -364,14 +364,14 @@ fn get_block_receipts() {
 	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
 
 	let cur_status = status(provider.client.chain_info());
-	let my_status = write_handshake(&cur_status, &capabilities, &flow_params);
+	let my_status = write_handshake(&cur_status, &capabilities, Some(&flow_params));
 
 	provider.client.add_blocks(1000, EachBlockWith::Nothing);
 
 	let cur_status = status(provider.client.chain_info());
 
 	{
-		let packet_body = write_handshake(&cur_status, &capabilities, &flow_params);	
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
 		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
 		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
 	}
@@ -419,7 +419,7 @@ fn get_state_proofs() {
 	let cur_status = status(provider.client.chain_info());
 
 	{
-		let packet_body = write_handshake(&cur_status, &capabilities, &flow_params);	
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
 		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body.clone()));	
 		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &packet_body);
 	}
@@ -468,7 +468,7 @@ fn get_contract_code() {
 	let cur_status = status(provider.client.chain_info());
 
 	{
-		let packet_body = write_handshake(&cur_status, &capabilities, &flow_params);	
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
 		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body.clone()));	
 		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &packet_body);
 	}