Add: Public hostname resolution (needed for testing)

src/main.rs

@@ -1,11 +1,11 @@
 //! Binary entry point that wires configuration, UDP listener, optional TLS listener, and allocation handling.
 //! Backlog: graceful shutdown signals, structured metrics, and coordinated lifecycle management across listeners.
 use std::net::SocketAddr;
-use std::net::{IpAddr, Ipv4Addr};
+use std::net::{IpAddr, Ipv4Addr, ToSocketAddrs};
 use std::sync::Arc;
 use std::time::Duration;
 use tokio::net::UdpSocket;
-use tracing::{error, info};
+use tracing::{error, info, warn};
 
 // Use the library crate's public modules instead of local `mod` declarations.
 use niom_turn::alloc::AllocationManager;
@@ -14,6 +14,25 @@ use niom_turn::auth::{AuthManager, InMemoryStore};
 use niom_turn::config::{AuthOptions, Config};
 use niom_turn::rate_limit::RateLimiters;
 
+// Workaround: allow relay.* config fields to be hostnames by resolving them once at startup.
+fn resolve_host_or_ip(label: &str, value: &str) -> Option<IpAddr> {
+    if let Ok(ip) = value.parse() {
+        return Some(ip);
+    }
+
+    let target = format!("{}:0", value);
+    match target.to_socket_addrs() {
+        Ok(mut addrs) => addrs.next().map(|addr| addr.ip()).or_else(|| {
+            warn!("workaround: {}='{}' resolved to no addresses", label, value);
+            None
+        }),
+        Err(e) => {
+            warn!("workaround: failed to resolve {}='{}': {:?}", label, value, e);
+            None
+        }
+    }
+}
+
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     // Bootstrap configuration: prefer appsettings.json, otherwise rely on baked-in demo defaults.
@@ -90,15 +109,14 @@ async fn main() -> anyhow::Result<()> {
         .relay
         .relay_bind_ip
         .as_deref()
-        .unwrap_or("0.0.0.0")
-        .parse()
+        .and_then(|s| resolve_host_or_ip("relay.relay_bind_ip", s))
         .unwrap_or(IpAddr::V4(Ipv4Addr::UNSPECIFIED));
 
     let advertised_ip: Option<IpAddr> = cfg
         .relay
         .advertised_ip
         .as_deref()
-        .and_then(|s| s.parse().ok());
+        .and_then(|s| resolve_host_or_ip("relay.advertised_ip", s));
 
     let alloc_mgr = AllocationManager::new_with_options(AllocationOptions {
         relay_bind_ip,