Increase limit on light client response size (#5461)

* Increase limit on light client response size

* Address review

substrate/client/network/src/protocol/light_client_handler.rs

@@ -77,7 +77,8 @@ use wasm_timer::Instant;
 /// Configuration options for `LightClientHandler` behaviour.
 #[derive(Debug, Clone)]
 pub struct Config {
-	max_data_size: usize,
+	max_request_size: usize,
+	max_response_size: usize,
 	max_pending_requests: usize,
 	inactivity_timeout: Duration,
 	request_timeout: Duration,
@@ -87,13 +88,15 @@ pub struct Config {
 impl Config {
 	/// Create a fresh configuration with the following options:
 	///
-	/// - max. data size = 1 MiB
+	/// - max. request size = 1 MiB
+	/// - max. response size = 16 MiB
 	/// - max. pending requests = 128
 	/// - inactivity timeout = 15s
 	/// - request timeout = 15s
 	pub fn new(id: &ProtocolId) -> Self {
 		let mut c = Config {
-			max_data_size: 1024 * 1024,
+			max_request_size: 1 * 1024 * 1024,
+			max_response_size: 16 * 1024 * 1024,
 			max_pending_requests: 128,
 			inactivity_timeout: Duration::from_secs(15),
 			request_timeout: Duration::from_secs(15),
@@ -103,9 +106,15 @@ impl Config {
 		c
 	}
 
-	/// Limit the max. length of incoming request bytes.
-	pub fn set_max_data_size(&mut self, v: usize) -> &mut Self {
-		self.max_data_size = v;
+	/// Limit the max. length in bytes of a request.
+	pub fn set_max_request_size(&mut self, v: usize) -> &mut Self {
+		self.max_request_size = v;
+		self
+	}
+
+	/// Limit the max. length in bytes of a response.
+	pub fn set_max_response_size(&mut self, v: usize) -> &mut Self {
+		self.max_response_size = v;
 		self
 	}
 
@@ -654,7 +663,7 @@ where
 
 	fn new_handler(&mut self) -> Self::ProtocolsHandler {
 		let p = InboundProtocol {
-			max_data_size: self.config.max_data_size,
+			max_request_size: self.config.max_request_size,
 			protocol: self.config.protocol.clone(),
 		};
 		OneShotHandler::new(SubstreamProtocol::new(p), self.config.inactivity_timeout)
@@ -841,7 +850,7 @@ where
 					let protocol = OutboundProtocol {
 						request: buf,
 						request_id: id,
-						max_data_size: self.config.max_data_size,
+						max_response_size: self.config.max_response_size,
 						protocol: self.config.protocol.clone(),
 					};
 					self.peers.get_mut(&peer).map(|info| info.status = PeerStatus::BusyWith(id));
@@ -1008,7 +1017,7 @@ pub enum Event<T> {
 #[derive(Debug, Clone)]
 pub struct InboundProtocol {
 	/// The max. request length in bytes.
-	max_data_size: usize,
+	max_request_size: usize,
 	/// The protocol to use for upgrade negotiation.
 	protocol: Bytes,
 }
@@ -1032,7 +1041,7 @@ where
 
     fn upgrade_inbound(self, mut s: T, _: Self::Info) -> Self::Future {
 		let future = async move {
-			let vec = read_one(&mut s, self.max_data_size).await?;
+			let vec = read_one(&mut s, self.max_request_size).await?;
 			match api::v1::light::Request::decode(&vec[..]) {
 				Ok(r) => Ok(Event::Request(r, s)),
 				Err(e) => Err(ReadOneError::Io(io::Error::new(io::ErrorKind::Other, e)))
@@ -1051,8 +1060,8 @@ pub struct OutboundProtocol {
 	request: Vec<u8>,
 	/// Local identifier for the request. Used to associate it with a response.
 	request_id: u64,
-	/// The max. request length in bytes.
-	max_data_size: usize,
+	/// The max. response length in bytes.
+	max_response_size: usize,
 	/// The protocol to use for upgrade negotiation.
 	protocol: Bytes,
 }
@@ -1077,7 +1086,7 @@ where
     fn upgrade_outbound(self, mut s: T, _: Self::Info) -> Self::Future {
 		let future = async move {
 			write_one(&mut s, &self.request).await?;
-			let vec = read_one(&mut s, self.max_data_size).await?;
+			let vec = read_one(&mut s, self.max_response_size).await?;
 			api::v1::light::Response::decode(&vec[..])
 				.map(|r| Event::Response(self.request_id, r))
 				.map_err(|e| {