[stable2412] Backport #6323 (#6478)

Co-authored-by: GitHub Action <[email protected]>

prdoc/pr_6454.prdoc

@@ -0,0 +1,7 @@
+title: 'rpc server: fix ipv6 host filter for localhost'
+doc:
+- audience: Node Operator
+  description: "This PR fixes that ipv6 connections to localhost was faulty rejected by the host filter because only [::1] was allowed"
+crates:
+- name: sc-rpc-server
+  bump: patch

substrate/client/rpc-servers/src/utils.rs

@@ -193,14 +193,11 @@ pub(crate) fn host_filtering(enabled: bool, addr: SocketAddr) -> Option<HostFilt
 	if enabled {
 		// NOTE: The listening addresses are whitelisted by default.
 
-		let mut hosts = Vec::new();
-
-		if addr.is_ipv4() {
-			hosts.push(format!("localhost:{}", addr.port()));
-			hosts.push(format!("127.0.0.1:{}", addr.port()));
-		} else {
-			hosts.push(format!("[::1]:{}", addr.port()));
-		}
+		let hosts = [
+			format!("localhost:{}", addr.port()),
+			format!("127.0.0.1:{}", addr.port()),
+			format!("[::1]:{}", addr.port()),
+		];
 
 		Some(HostFilterLayer::new(hosts).expect("Valid hosts; qed"))
 	} else {