site/dashboard.html

@@ -873,6 +873,7 @@ async function refresh() {
     document.getElementById('totalQueries').textContent = formatNumber(q.total);
     document.getElementById('uptime').textContent = formatUptime(stats.uptime_secs);
     document.getElementById('uptimeSub').textContent = formatUptimeSub(stats.uptime_secs);
+    document.getElementById('footerUpstream').textContent = stats.upstream || '';
     document.getElementById('overrideCount').textContent = stats.overrides.active;
     document.getElementById('blockedCount').textContent = formatNumber(q.blocked);
     const bl = stats.blocking;
@@ -1150,7 +1151,8 @@ setInterval(refresh, 2000);
 </script>
 
 <div style="text-align:center;padding:0.8rem;font-family:var(--font-mono);font-size:0.68rem;color:var(--text-dim);">
-  Logs: <span id="logPath" style="user-select:all;">macOS: /usr/local/var/log/numa.log · Linux: journalctl -u numa -f</span>
+  Upstream: <span id="footerUpstream" style="user-select:all;color:var(--emerald);"></span>
+  · Logs: <span id="logPath" style="user-select:all;">macOS: /usr/local/var/log/numa.log · Linux: journalctl -u numa -f</span>
   · <a href="https://github.com/razvandimescu/numa" target="_blank" rel="noopener" style="color:var(--amber);text-decoration:none;">GitHub</a>
 </div>
 

src/api.rs

@@ -126,6 +126,7 @@ struct QueryLogResponse {
 #[derive(Serialize)]
 struct StatsResponse {
     uptime_secs: u64,
+    upstream: String,
     queries: QueriesStats,
     cache: CacheStats,
     overrides: OverrideStats,
@@ -341,8 +342,9 @@ async fn diagnose(
     }
 
     // Check upstream (async, no locks held)
+    let upstream = *ctx.upstream.lock().unwrap();
     let (upstream_matched, upstream_detail) =
-        forward_query_for_diagnose(&domain_lower, ctx.upstream, ctx.timeout).await;
+        forward_query_for_diagnose(&domain_lower, upstream, ctx.timeout).await;
     steps.push(DiagnoseStep {
         source: "upstream".to_string(),
         matched: upstream_matched,
@@ -434,8 +436,11 @@ async fn stats(State(ctx): State<Arc<ServerCtx>>) -> Json<StatsResponse> {
     let override_count = ctx.overrides.lock().unwrap().active_count();
     let bl_stats = ctx.blocklist.lock().unwrap().stats();
 
+    let upstream = ctx.upstream.lock().unwrap().to_string();
+
     Json(StatsResponse {
         uptime_secs: snap.uptime_secs,
+        upstream,
         queries: QueriesStats {
             total: snap.total,
             forwarded: snap.forwarded,

src/ctx.rs

@@ -32,7 +32,10 @@ pub struct ServerCtx {
     pub services: Mutex<ServiceStore>,
     pub lan_peers: Mutex<PeerStore>,
     pub forwarding_rules: Vec<ForwardingRule>,
-    pub upstream: SocketAddr,
+    pub upstream: Mutex<SocketAddr>,
+    pub upstream_auto: bool,
+    pub upstream_port: u16,
+    pub lan_ip: Mutex<std::net::Ipv4Addr>,
     pub timeout: Duration,
     pub proxy_tld: String,
     pub proxy_tld_suffix: String, // pre-computed ".{tld}" to avoid per-query allocation
@@ -132,7 +135,7 @@ pub async fn handle_query(
             } else {
                 let upstream =
                     crate::system_dns::match_forwarding_rule(&qname, &ctx.forwarding_rules)
-                        .unwrap_or(ctx.upstream);
+                        .unwrap_or_else(|| *ctx.upstream.lock().unwrap());
                 match forward_query(&query, upstream, ctx.timeout).await {
                     Ok(resp) => {
                         ctx.cache.lock().unwrap().insert(&qname, qtype, &resp);

src/lan.rs

@@ -57,6 +57,10 @@ impl PeerStore {
             })
             .collect()
     }
+
+    pub fn clear(&mut self) {
+        self.peers.clear();
+    }
 }
 
 // --- Multicast ---
@@ -109,7 +113,7 @@ pub async fn start_lan_discovery(ctx: Arc<ServerCtx>, config: &LanConfig) {
             .as_nanos() as u64;
         pid ^ ts
     };
-    let local_ip = detect_lan_ip().unwrap_or(Ipv4Addr::LOCALHOST);
+    let local_ip = *ctx.lan_ip.lock().unwrap();
     info!(
         "LAN discovery on {}:{}, local IP {}, instance {:016x}",
         multicast_group, port, local_ip, instance_id
@@ -138,7 +142,6 @@ pub async fn start_lan_discovery(ctx: Arc<ServerCtx>, config: &LanConfig) {
     // Spawn sender
     let sender_ctx = Arc::clone(&ctx);
     let sender_socket = Arc::clone(&socket);
-    let local_ip_str = local_ip.to_string();
     let dest = SocketAddr::new(IpAddr::V4(multicast_group), port);
     tokio::spawn(async move {
         let mut ticker = tokio::time::interval(interval);
@@ -158,9 +161,10 @@ pub async fn start_lan_discovery(ctx: Arc<ServerCtx>, config: &LanConfig) {
             if services.is_empty() {
                 continue;
             }
+            let current_ip = sender_ctx.lan_ip.lock().unwrap().to_string();
             let announcement = Announcement {
                 instance_id,
-                host: local_ip_str.clone(),
+                host: current_ip,
                 services,
             };
             if let Ok(json) = serde_json::to_vec(&announcement) {

src/main.rs

@@ -86,7 +86,10 @@ async fn main() -> numa::Result<()> {
     let system_dns = discover_system_dns();
 
     let upstream_addr = if config.upstream.address.is_empty() {
-        system_dns.default_upstream.unwrap_or_else(|| {
+        system_dns
+            .default_upstream
+            .or_else(numa::system_dns::detect_dhcp_dns)
+            .unwrap_or_else(|| {
                 info!("could not detect system DNS, falling back to 9.9.9.9 (Quad9)");
                 "9.9.9.9".to_string()
             })
@@ -129,7 +132,10 @@ async fn main() -> numa::Result<()> {
         services: Mutex::new(service_store),
         lan_peers: Mutex::new(numa::lan::PeerStore::new(config.lan.peer_timeout_secs)),
         forwarding_rules,
-        upstream,
+        upstream: Mutex::new(upstream),
+        upstream_auto: config.upstream.address.is_empty(),
+        upstream_port: config.upstream.port,
+        lan_ip: Mutex::new(numa::lan::detect_lan_ip().unwrap_or(std::net::Ipv4Addr::LOCALHOST)),
         timeout: Duration::from_millis(config.upstream.timeout_ms),
         proxy_tld_suffix: if config.proxy.tld.is_empty() {
             String::new()
@@ -240,6 +246,14 @@ async fn main() -> numa::Result<()> {
         }
     }
 
+    // Spawn network change watcher (upstream re-detection, LAN IP update, peer flush)
+    {
+        let watch_ctx = Arc::clone(&ctx);
+        tokio::spawn(async move {
+            network_watch_loop(watch_ctx).await;
+        });
+    }
+
     // Spawn LAN service discovery
     if config.lan.enabled {
         let lan_ctx = Arc::clone(&ctx);
@@ -264,6 +278,52 @@ async fn main() -> numa::Result<()> {
     }
 }
 
+async fn network_watch_loop(ctx: Arc<numa::ctx::ServerCtx>) {
+    let mut interval = tokio::time::interval(Duration::from_secs(30));
+    interval.tick().await; // skip immediate tick
+
+    loop {
+        interval.tick().await;
+        let mut changed = false;
+
+        // Check LAN IP change
+        if let Some(new_ip) = numa::lan::detect_lan_ip() {
+            let mut current_ip = ctx.lan_ip.lock().unwrap();
+            if new_ip != *current_ip {
+                info!("LAN IP changed: {} → {}", current_ip, new_ip);
+                *current_ip = new_ip;
+                changed = true;
+            }
+        }
+
+        // Check upstream change (only for auto-detected upstream)
+        if ctx.upstream_auto {
+            let dns_info = numa::system_dns::discover_system_dns();
+            // Use detected upstream, or try DHCP-provided DNS, or fall back to Quad9
+            let new_addr = dns_info
+                .default_upstream
+                .or_else(numa::system_dns::detect_dhcp_dns)
+                .unwrap_or_else(|| "9.9.9.9".to_string());
+            if let Ok(new_upstream) =
+                format!("{}:{}", new_addr, ctx.upstream_port).parse::<SocketAddr>()
+            {
+                let mut upstream = ctx.upstream.lock().unwrap();
+                if new_upstream != *upstream {
+                    info!("upstream changed: {} → {}", *upstream, new_upstream);
+                    *upstream = new_upstream;
+                    changed = true;
+                }
+            }
+        }
+
+        // Flush stale LAN peers on any network change
+        if changed {
+            ctx.lan_peers.lock().unwrap().clear();
+            info!("flushed LAN peers after network change");
+        }
+    }
+}
+
 async fn load_blocklists(ctx: &ServerCtx, lists: &[String]) {
     let downloaded = download_blocklists(lists).await;
 

src/system_dns.rs

@@ -205,6 +205,53 @@ fn read_upstream_from_file(path: &str) -> Option<String> {
     None
 }
 
+/// Detect DNS server from DHCP lease — fallback when scutil/resolv.conf only shows 127.0.0.1.
+/// On macOS: parses `ipconfig getpacket en0` for domain_name_server.
+/// On Linux/Windows: returns None (not implemented yet).
+pub fn detect_dhcp_dns() -> Option<String> {
+    #[cfg(target_os = "macos")]
+    {
+        detect_dhcp_dns_macos()
+    }
+    #[cfg(not(target_os = "macos"))]
+    {
+        None
+    }
+}
+
+#[cfg(target_os = "macos")]
+fn detect_dhcp_dns_macos() -> Option<String> {
+    // Try common interfaces
+    for iface in &["en0", "en1"] {
+        let output = std::process::Command::new("ipconfig")
+            .args(["getpacket", iface])
+            .output()
+            .ok()?;
+        let text = String::from_utf8_lossy(&output.stdout);
+        for line in text.lines() {
+            if line.contains("domain_name_server") {
+                // Format: "domain_name_server (ip_mult): {213.154.124.25, 1.0.0.1}"
+                if let Some(braces) = line.split('{').nth(1) {
+                    let inner = braces.trim_end_matches('}').trim();
+                    // Take the first non-loopback DNS server
+                    for addr in inner.split(',') {
+                        let addr = addr.trim();
+                        if !addr.is_empty()
+                            && addr != "127.0.0.1"
+                            && addr != "0.0.0.0"
+                            && addr.parse::<std::net::Ipv4Addr>().is_ok()
+                        {
+                            log::info!("detected DHCP DNS: {}", addr);
+                            return Some(addr.to_string());
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
 // --- Windows implementation ---
 
 #[cfg(windows)]