[wpiutil] Add mDNS resolver and announcer (#3733)

wpiutil/src/main/java/edu/wpi/first/util/MulticastServiceAnnouncer.java

@@ -0,0 +1,45 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.util;
+
+import java.util.Map;
+
+/** Class to announce over mDNS that a service is available. */
+public class MulticastServiceAnnouncer implements AutoCloseable {
+  private final int m_handle;
+
+  /**
+   * Creates a MulticastServiceAnnouncer.
+   *
+   * @param serviceName service name
+   * @param serviceType service type
+   * @param port port
+   * @param txt txt
+   */
+  public MulticastServiceAnnouncer(
+      String serviceName, String serviceType, int port, Map<String, String> txt) {
+    String[] keys = txt.keySet().toArray(String[]::new);
+    String[] values = txt.values().toArray(String[]::new);
+    m_handle =
+        WPIUtilJNI.createMulticastServiceAnnouncer(serviceName, serviceType, port, keys, values);
+  }
+
+  @Override
+  public void close() {
+    WPIUtilJNI.freeMulticastServiceAnnouncer(m_handle);
+  }
+
+  public void start() {
+    WPIUtilJNI.startMulticastServiceAnnouncer(m_handle);
+  }
+
+  public void stop() {
+    WPIUtilJNI.stopMulticastServiceAnnouncer(m_handle);
+  }
+
+  public boolean hasImplementation() {
+    return WPIUtilJNI.getMulticastServiceAnnouncerHasImplementation(m_handle);
+  }
+}

wpiutil/src/main/java/edu/wpi/first/util/MulticastServiceResolver.java

@@ -0,0 +1,44 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.util;
+
+/** Class to resolve a service over mDNS. */
+public class MulticastServiceResolver implements AutoCloseable {
+  private final int m_handle;
+
+  /**
+   * Creates a MulticastServiceResolver.
+   *
+   * @param serviceType service type to look for
+   */
+  public MulticastServiceResolver(String serviceType) {
+    m_handle = WPIUtilJNI.createMulticastServiceResolver(serviceType);
+  }
+
+  @Override
+  public void close() {
+    WPIUtilJNI.freeMulticastServiceResolver(m_handle);
+  }
+
+  public void start() {
+    WPIUtilJNI.startMulticastServiceResolver(m_handle);
+  }
+
+  public void stop() {
+    WPIUtilJNI.stopMulticastServiceResolver(m_handle);
+  }
+
+  public boolean hasImplementation() {
+    return WPIUtilJNI.getMulticastServiceResolverHasImplementation(m_handle);
+  }
+
+  public int getEventHandle() {
+    return WPIUtilJNI.getMulticastServiceResolverEventHandle(m_handle);
+  }
+
+  public ServiceData getData() {
+    return WPIUtilJNI.getMulticastServiceResolverData(m_handle);
+  }
+}

wpiutil/src/main/java/edu/wpi/first/util/ServiceData.java

@@ -0,0 +1,66 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.util;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/** Service data for MulticastServiceResolver. */
+public class ServiceData {
+  /**
+   * Constructs a ServiceData.
+   *
+   * @param ipv4Address ipv4Address
+   * @param port port
+   * @param serviceName found service name
+   * @param hostName found host name
+   * @param keys txt keys
+   * @param values txt values
+   */
+  public ServiceData(
+      long ipv4Address,
+      int port,
+      String serviceName,
+      String hostName,
+      String[] keys,
+      String[] values) {
+    this.m_serviceName = serviceName;
+    this.m_hostName = hostName;
+    this.m_port = port;
+    this.m_ipv4Address = ipv4Address;
+
+    m_txt = new HashMap<>();
+
+    for (int i = 0; i < keys.length; i++) {
+      m_txt.put(keys[i], values[i]);
+    }
+  }
+
+  public Map<String, String> getTxt() {
+    return m_txt;
+  }
+
+  public String getHostName() {
+    return m_hostName;
+  }
+
+  public String getServiceName() {
+    return m_serviceName;
+  }
+
+  public int getPort() {
+    return m_port;
+  }
+
+  public long getIpv4Address() {
+    return m_ipv4Address;
+  }
+
+  private final Map<String, String> m_txt;
+  private final long m_ipv4Address;
+  private final int m_port;
+  private final String m_serviceName;
+  private final String m_hostName;
+}

wpiutil/src/main/java/edu/wpi/first/util/WPIUtilJNI.java

@@ -122,4 +122,29 @@ public final class WPIUtilJNI {
    */
   public static native int[] waitForObjectsTimeout(int[] handles, double timeout)
       throws InterruptedException;
+
+  public static native int createMulticastServiceAnnouncer(
+      String serviceName, String serviceType, int port, String[] keys, String[] values);
+
+  public static native void freeMulticastServiceAnnouncer(int handle);
+
+  public static native void startMulticastServiceAnnouncer(int handle);
+
+  public static native void stopMulticastServiceAnnouncer(int handle);
+
+  public static native boolean getMulticastServiceAnnouncerHasImplementation(int handle);
+
+  public static native int createMulticastServiceResolver(String serviceType);
+
+  public static native void freeMulticastServiceResolver(int handle);
+
+  public static native void startMulticastServiceResolver(int handle);
+
+  public static native void stopMulticastServiceResolver(int handle);
+
+  public static native boolean getMulticastServiceResolverHasImplementation(int handle);
+
+  public static native int getMulticastServiceResolverEventHandle(int handle);
+
+  public static native ServiceData getMulticastServiceResolverData(int handle);
 }