fix relaychain rpc external (#2613)

Author: xlc

Diff for: node/cli/src/command.rs

@@ -19,6 +19,8 @@
 // Disable the following lints
 #![allow(clippy::borrowed_box)]
 
+use std::net::SocketAddr;
+
 use crate::cli::{Cli, RelayChainCli, Subcommand};
 use cumulus_primitives_core::ParaId;
 use frame_benchmarking_cli::{BenchmarkCmd, SUBSTRATE_REFERENCE_HARDWARE};
@@ -515,6 +517,10 @@ impl CliConfiguration<Self> for RelayChainCli {
 			.or_else(|| self.base_path.clone().map(Into::into)))
 	}
 
+	fn rpc_addr(&self, default_listen_port: u16) -> Result<Option<SocketAddr>> {
+		self.base.base.rpc_addr(default_listen_port)
+	}
+
 	fn prometheus_config(
 		&self,
 		default_listen_port: u16,