Fix nativeDnssd(InetAddress) pairing hang from IP SRV host.

Keep DNS-SD host null so mDNSResponder publishes the system hostname
with A/AAAA; only scope registration by interface index. A literal IP as
host became an SRV target with no address record.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: kgoderis

CHANGES.md

@@ -3,6 +3,7 @@
 * Add pluggable `HomekitAdvertiser` with native DNS-SD / Bonjour implementation (`DnssdHomekitAdvertiser`) so macOS can advertise `_hap._tcp` without binding UDP 5353 [#212](https://github.com/hap-java/HAP-Java/issues/212) (see [docs/NATIVE_DNSSD.md](docs/NATIVE_DNSSD.md))
 * Extract shared HAP TXT helpers (`HapDnsTxt`) with stable key order; JmDNS and native advertisers publish the same property set
 * JNA (`net.java.dev.jna:jna`) is **optional** for `nativeDnssd()`; JmDNS-only consumers do not need it. Applications should choose `jmdns(...)` or `nativeDnssd(InetAddress)` explicitly (`auto(...)` is deprecated)
+* `nativeDnssd(InetAddress)` scopes DNS-SD by interface index only and keeps SRV `host` null (system hostname). Passing an IP literal as host broke pairing (SRV target with no A record)
 
 # HAP-Java 2.0.9
 * Fix Set Duration and Remaining Duration characteristics to advertise format `uint32` instead of `int` [#202](https://github.com/hap-java/HAP-Java/issues/202)

docs/NATIVE_DNSSD.md

@@ -40,7 +40,7 @@ import java.net.InetAddress;
 
 InetAddress bind = InetAddress.getByName("192.168.0.6");
 
-// Prefer scoping native registration to the HAP bind address (interface + SRV host):
+// Prefer scoping native registration to the HAP bind interface (SRV host stays system default):
 HomekitServer server =
     new HomekitServer(bind, 9124, HomekitAdvertisers.nativeDnssd(bind));
 
@@ -91,7 +91,7 @@ setConfigurationIndex(int)
 | `jmdns(JmDNS)` | Wrap an existing JmDNS (force JmDNS / share openHAB’s instance) |
 | `jmdns(InetAddress)` | Create dedicated JmDNS on that address |
 | `nativeDnssd()` | Native Bonjour on **all** interfaces (`interfaceIndex = 0`, default host) |
-| `nativeDnssd(InetAddress)` | Native Bonjour scoped to that address’s interface index + SRV host |
+| `nativeDnssd(InetAddress)` | Native Bonjour on that address’s interface index; SRV host = system default (`null`) |
 | `isNativeDnssdSupported()` | Whether JNA + dns_sd **load** (not a live register probe) |
 | `auto(InetAddress)` | **Deprecated** — prefer an explicit `jmdns` / `nativeDnssd` choice |
 
@@ -108,7 +108,7 @@ When an advertiser is supplied, `createBridge` / `createStandaloneAccessory` use
 
 * **JNA** is an **optional** dependency. It loads `System` on macOS/Darwin and `dns_sd` elsewhere (Avahi Bonjour compatibility). Missing JNA surfaces as `LinkageError` and `isNativeDnssdSupported()` returns `false`.
 * `DNSServiceRegister` receives the TCP port in **network byte order**.
-* Default `nativeDnssd()` uses `interfaceIndex = 0` (all interfaces) and `host = null` (system hostname). Prefer `nativeDnssd(InetAddress)` when the HAP TCP listener is bound to one LAN address.
+* Default `nativeDnssd()` uses `interfaceIndex = 0` (all interfaces) and `host = null` (system hostname). Prefer `nativeDnssd(InetAddress)` to limit the interface index when the HAP TCP listener is bound to one LAN address — still with `host = null`. Never pass a raw IP as DNS-SD `host` (no A record → Home hangs on “Setting up”).
 * TXT is RFC 6763 length-prefixed `key=value` bytes (`HapDnsTxt.encodeTxt`). Key insertion order is stable (`LinkedHashMap`); RFC 6763 does not require a particular pair order.
 * A daemon thread runs `DNSServiceProcessResult` until `DNSServiceRefDeallocate` on `stop()` / re-register.
 * Re-registration (discoverability, MAC, `c#`) deallocates and registers again — same pattern as the JmDNS advertiser.

src/main/java/io/github/hapjava/server/HomekitAdvertisers.java

@@ -18,7 +18,7 @@
  * // Force JmDNS (e.g. share openHAB's instance):
  * HomekitAdvertiser adv = HomekitAdvertisers.jmdns(sharedJmDNS);
  *
- * // Native DNS-SD limited to one LAN address / interface:
+ * // Native DNS-SD on the interface that owns the HAP bind address (SRV host = system default):
  * HomekitAdvertiser adv = HomekitAdvertisers.nativeDnssd(InetAddress.getByName("192.168.0.6"));
  * }</pre>
  *
@@ -68,8 +68,10 @@ public static HomekitAdvertiser nativeDnssd() {
   }
 
   /**
-   * Native DNS-SD / Bonjour advertiser scoped to {@code localAddress}: SRV host is that address and
-   * registration uses the matching network interface index when resolvable.
+   * Native DNS-SD / Bonjour advertiser scoped to the interface that owns {@code localAddress}.
+   * Registration uses that interface index when resolvable; SRV host stays {@code null} (system
+   * hostname). Passing an IP literal as DNS-SD host is incorrect — it yields an SRV target with no
+   * A record and breaks Home pairing.
    *
    * @param localAddress LAN address the HAP TCP server listens on
    * @return a native DNS-SD advertiser

src/main/java/io/github/hapjava/server/impl/dnssd/DnssdHomekitAdvertiser.java

@@ -22,9 +22,10 @@
  *
  * <p>Uses JNA to call {@code DNSServiceRegister} / {@code DNSServiceRefDeallocate}.
  *
- * <p>Pass an {@link InetAddress} to scope registration to one LAN interface/host; the no-arg
- * constructor registers on all interfaces ({@code interfaceIndex = 0}) with the system default
- * hostname ({@code host = null}).
+ * <p>Pass an {@link InetAddress} to scope registration to one LAN <em>interface</em>; SRV host
+ * stays {@code null} so mDNSResponder advertises the system hostname (with A/AAAA). Passing a raw
+ * IP as DNS-SD {@code host} breaks pairing — the daemon does not synthesize an A record for that
+ * name. The no-arg constructor registers on all interfaces ({@code interfaceIndex = 0}).
  *
  * @author Karel Goderis
  */
@@ -62,21 +63,25 @@ public DnssdHomekitAdvertiser() {
   }
 
   /**
-   * Scope registration to {@code localAddress}: SRV host is that address's host string, and the
-   * DNS-SD interface index is taken from the matching {@link NetworkInterface} when available.
+   * Scope registration to the network interface that owns {@code localAddress}. SRV {@code host} is
+   * left {@code null} (system default hostname + A/AAAA via mDNSResponder).
+   *
+   * <p>Do not pass {@code localAddress.getHostAddress()} as DNS-SD host: a literal IP becomes an
+   * SRV target name with no A record, and Home pairing hangs after accepting the QR code.
    *
    * @param localAddress LAN address the HAP TCP listener uses
    */
   public DnssdHomekitAdvertiser(InetAddress localAddress) {
-    this(resolveInterfaceIndex(localAddress), resolveHost(localAddress));
+    this(resolveInterfaceIndex(localAddress), null);
   }
 
   /**
    * Full control over DNS-SD {@code interfaceIndex} and {@code host}.
    *
    * @param interfaceIndex {@link #INTERFACE_INDEX_ANY} (0) for all interfaces, or a platform
    *     interface index from {@link NetworkInterface#getIndex()}
-   * @param host SRV target host (IP or DNS name), or {@code null} for the system default hostname
+   * @param host SRV target <strong>DNS hostname</strong>, or {@code null} for the system default.
+   *     Must not be a raw IP literal — DNS-SD will not register an A/AAAA for it.
    */
   public DnssdHomekitAdvertiser(int interfaceIndex, String host) {
     if (!SUPPORTED) {
@@ -125,11 +130,6 @@ private static boolean detectSupport() {
     }
   }
 
-  private static String resolveHost(InetAddress localAddress) {
-    Objects.requireNonNull(localAddress, "localAddress");
-    return localAddress.getHostAddress();
-  }
-
   private static int resolveInterfaceIndex(InetAddress localAddress) {
     Objects.requireNonNull(localAddress, "localAddress");
     try {

src/test/java/io/github/hapjava/server/impl/dnssd/DnssdHomekitAdvertiserTest.java

@@ -93,7 +93,8 @@ public void advertiseRegistersHapService() throws Exception {
 
   @Test
   public void advertisePassesConfiguredInterfaceIndexAndHost() throws Exception {
-    subject = new DnssdHomekitAdvertiser(dnsSd, 4, "192.168.0.6");
+    // Advanced ctor may pass a real DNS hostname; raw IPs must not be used as DNS-SD host.
+    subject = new DnssdHomekitAdvertiser(dnsSd, 4, "bridge.local");
     when(dnsSd.DNSServiceRegister(
             any(PointerByReference.class),
             anyInt(),
@@ -129,7 +130,15 @@ public void advertisePassesConfiguredInterfaceIndexAndHost() throws Exception {
             any());
 
     assertThat(ifIndex.getValue()).isEqualTo(4);
-    assertThat(host.getValue()).isEqualTo("192.168.0.6");
+    assertThat(host.getValue()).isEqualTo("bridge.local");
+  }
+
+  @Test
+  public void inetAddressConstructorLeavesHostNull() {
+    // Package-visible mock ctor mirrors InetAddress behaviour: interface scoped, host=null.
+    subject = new DnssdHomekitAdvertiser(dnsSd, 7, null);
+    assertThat(subject.getInterfaceIndex()).isEqualTo(7);
+    assertThat(subject.getHost()).isNull();
   }
 
   @Test