Allow configurable control server bind address

This commit adds the ability to bind the control server to a specific network
interface via an additional flag `--control-addr`.

By default it listens on `0.0.0.0` which is the previous behaviour.

src/main.rs

@@ -47,6 +47,10 @@ enum Command {
         /// Optional secret for authentication.
         #[clap(short, long, env = "BORE_SECRET", hide_env_values = true)]
         secret: Option<String>,
+
+        /// IP address for the control server. Bore clients must reach this address.
+        #[clap(long, default_value = "0.0.0.0")]
+        control_addr: String,
     },
 }
 
@@ -67,6 +71,7 @@ async fn run(command: Command) -> Result<()> {
             min_port,
             max_port,
             secret,
+            control_addr,
         } => {
             let port_range = min_port..=max_port;
             if port_range.is_empty() {
@@ -74,7 +79,7 @@ async fn run(command: Command) -> Result<()> {
                     .error(ErrorKind::InvalidValue, "port range is empty")
                     .exit();
             }
-            Server::new(port_range, secret.as_deref()).listen().await?;
+            Server::new(port_range, secret.as_deref(), control_addr).listen().await?;
         }
     }
 

src/server.rs

@@ -1,6 +1,6 @@
 //! Server implementation for the `bore` service.
 
-use std::{io, net::SocketAddr, ops::RangeInclusive, sync::Arc, time::Duration};
+use std::{io, ops::RangeInclusive, sync::Arc, time::Duration};
 
 use anyhow::Result;
 use dashmap::DashMap;
@@ -23,25 +23,28 @@ pub struct Server {
 
     /// Concurrent map of IDs to incoming connections.
     conns: Arc<DashMap<Uuid, TcpStream>>,
+
+    /// IP address for the control server. Bore clients must reach this address.
+    control_addr: String,
 }
 
 impl Server {
     /// Create a new server with a specified minimum port number.
-    pub fn new(port_range: RangeInclusive<u16>, secret: Option<&str>) -> Self {
+    pub fn new(port_range: RangeInclusive<u16>, secret: Option<&str>, control_addr: String) -> Self {
         assert!(!port_range.is_empty(), "must provide at least one port");
         Server {
             port_range,
             conns: Arc::new(DashMap::new()),
             auth: secret.map(Authenticator::new),
+            control_addr: control_addr,
         }
     }
 
     /// Start the server, listening for new connections.
     pub async fn listen(self) -> Result<()> {
         let this = Arc::new(self);
-        let addr = SocketAddr::from(([0, 0, 0, 0], CONTROL_PORT));
-        let listener = TcpListener::bind(&addr).await?;
-        info!(?addr, "server listening");
+        let listener = TcpListener::bind((this.control_addr.as_ref(), CONTROL_PORT)).await?;
+        info!(?this.control_addr, "server listening");
 
         loop {
             let (stream, addr) = listener.accept().await?;