Implement NetworkRequest for litep2p (#7073)

# Description

Implements NetworkRequest::request for litep2p that we need for
networking benchmarks


## Review Notes

Duplicates implementation for NetworkService

https://github.com/paritytech/polkadot-sdk/blob/5bf9dd2a/substrate/client/network/src/service.rs#L1186-L1205

---------

Co-authored-by: command-bot <>

prdoc/pr_7073.prdoc

+title: Implement NetworkRequest for litep2p
+doc:
+- audience: Node Dev
+  description: |-
+    # Description
+
+    Implements NetworkRequest::request for litep2p that we need for networking benchmarks
+
+
+    ## Review Notes
+
+    Duplicates implementation for NetworkService
+    https://github.com/paritytech/polkadot-sdk/blob/5bf9dd2aa9bf944434203128783925bdc2ad8c01/substrate/client/network/src/service.rs#L1186-L1205
+crates:
+- name: sc-network
+  bump: patch

substrate/client/network/src/litep2p/service.rs

@@ -28,8 +28,8 @@ use crate::{
 	peer_store::PeerStoreProvider,
 	service::out_events,
 	Event, IfDisconnected, NetworkDHTProvider, NetworkEventStream, NetworkPeers, NetworkRequest,
-	NetworkSigner, NetworkStateInfo, NetworkStatus, NetworkStatusProvider, ProtocolName,
-	RequestFailure, Signature,
+	NetworkSigner, NetworkStateInfo, NetworkStatus, NetworkStatusProvider, OutboundFailure,
+	ProtocolName, RequestFailure, Signature,
 };
 
 use codec::DecodeAll;
@@ -526,13 +526,23 @@ impl NetworkStateInfo for Litep2pNetworkService {
 impl NetworkRequest for Litep2pNetworkService {
 	async fn request(
 		&self,
-		_target: PeerId,
-		_protocol: ProtocolName,
-		_request: Vec<u8>,
-		_fallback_request: Option<(Vec<u8>, ProtocolName)>,
-		_connect: IfDisconnected,
+		target: PeerId,
+		protocol: ProtocolName,
+		request: Vec<u8>,
+		fallback_request: Option<(Vec<u8>, ProtocolName)>,
+		connect: IfDisconnected,
 	) -> Result<(Vec<u8>, ProtocolName), RequestFailure> {
-		unimplemented!();
+		let (tx, rx) = oneshot::channel();
+
+		self.start_request(target, protocol, request, fallback_request, tx, connect);
+
+		match rx.await {
+			Ok(v) => v,
+			// The channel can only be closed if the network worker no longer exists. If the
+			// network worker no longer exists, then all connections to `target` are necessarily
+			// closed, and we legitimately report this situation as a "ConnectionClosed".
+			Err(_) => Err(RequestFailure::Network(OutboundFailure::ConnectionClosed)),
+		}
 	}
 
 	fn start_request(