better shutdown

Cargo.toml

@@ -6,4 +6,3 @@ members = ["salut", "desec"]
 lto = "fat"
 opt-level = 3
 strip = "symbols"
-panic = "abort"

salut/src/main.rs

@@ -48,13 +48,24 @@ async fn main() -> Result<(), anyhow::Error> {
     );
     let cert_clone = certs.clone();
     let host_clone = host.clone();
-    tokio::spawn(async move {
+    let tls_handle = tokio::spawn(async move {
         server::listen_tls(host_clone, cfg.tls_port, cert_clone)
             .await
             .expect("TLS listener")
     });
+    let starttls_handle = tokio::spawn(async move {
         server::listen_starttls(host, cfg.insecure_port, certs)
             .await
             .expect("STARTTLS listener");
-    Ok(())
+    });
+    tokio::select! {
+        _ = tls_handle => {
+            error!("tls handler returned unexpectedly");
+        },
+        _ = starttls_handle => {
+            error!("starttls handler returned unexpectedly");
+        },
+    };
+
+    Err(anyhow::anyhow!("unexpected server shutdown"))
 }