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/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?;