Configurable Zeroconf listen port

Author: devgianlu

conf.properties

@@ -12,6 +12,8 @@ auth.password=
 # Spotify authentication blob (BLOB only)
 auth.blob=
 ### Zeroconf ###
+# Listen on this port (`-1` for random)
+zeroconf.listenPort=-1
 # Listen on all interfaces (overrides `zeroconf.interfaces`)
 zeroconf.listenAll=true
 # Listen on these interfaces (comma separated list of names)

core/src/main/java/xyz/gianlu/librespot/DefaultConfiguration.java

@@ -115,6 +115,11 @@ public boolean zeroconfListenAll() {
         return true;
     }
 
+    @Override
+    public int zeroconfListenPort() {
+        return -1;
+    }
+
     @Override
     public @NotNull String[] zeroconfInterfaces() {
         return new String[0];

core/src/main/java/xyz/gianlu/librespot/FileConfiguration.java

@@ -6,6 +6,7 @@
 import org.jetbrains.annotations.Nullable;
 import xyz.gianlu.librespot.common.Utils;
 import xyz.gianlu.librespot.core.Session;
+import xyz.gianlu.librespot.core.ZeroconfServer;
 import xyz.gianlu.librespot.player.PlayerRunner;
 import xyz.gianlu.librespot.player.StreamFeeder;
 
@@ -187,6 +188,17 @@ public boolean zeroconfListenAll() {
         return getBoolean("zeroconf.listenAll", defaults.zeroconfListenAll());
     }
 
+    @Override
+    public int zeroconfListenPort() {
+        int val = getInt("zeroconf.listenPort", defaults.zeroconfListenPort());
+        if (val == -1) return val;
+
+        if (val < ZeroconfServer.MIN_PORT || val > ZeroconfServer.MAX_PORT)
+            throw new IllegalArgumentException("Illegal port number: " + val);
+
+        return 0;
+    }
+
     @NotNull
     @Override
     public String[] zeroconfInterfaces() {

core/src/main/java/xyz/gianlu/librespot/core/ZeroconfServer.java

@@ -30,8 +30,8 @@
  * @author Gianlu
  */
 public class ZeroconfServer implements Closeable {
-    private final static int MAX_PORT = 65536;
-    private final static int MIN_PORT = 1024;
+    public final static int MAX_PORT = 65536;
+    public final static int MIN_PORT = 1024;
     private static final Logger LOGGER = Logger.getLogger(ZeroconfServer.class);
     private static final byte[] EOL = new byte[]{'\r', '\n'};
     private static final JsonObject DEFAULT_GET_INFO_FIELDS = new JsonObject();
@@ -77,14 +77,17 @@ public class ZeroconfServer implements Closeable {
     private final HttpRunner runner;
     private final Session.Inner inner;
     private final DiffieHellman keys;
-    private Session session;
     private final JmDNS[] instances;
+    private Session session;
 
     private ZeroconfServer(Session.Inner inner, Configuration conf) throws IOException {
         this.inner = inner;
         this.keys = new DiffieHellman(inner.random);
 
-        int port = inner.random.nextInt((MAX_PORT - MIN_PORT) + 1) + MIN_PORT;
+        int port = conf.zeroconfListenPort();
+        if (port == -1)
+            port = inner.random.nextInt((MAX_PORT - MIN_PORT) + 1) + MIN_PORT;
+
         new Thread(this.runner = new HttpRunner(port), "zeroconf-http-server").start();
 
         InetAddress[] bound;
@@ -300,6 +303,8 @@ private void handleAddUser(OutputStream out, Map<String, String> params, String
     public interface Configuration {
         boolean zeroconfListenAll();
 
+        int zeroconfListenPort();
+
         @NotNull
         String[] zeroconfInterfaces();
     }