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

wpiutil/src/main/native/include/wpi/MulticastServiceAnnouncer.h

@@ -0,0 +1,61 @@
+// 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.
+
+#pragma once
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+#include <memory>
+#include <string>
+#include <string_view>
+#include <utility>
+
+#include "wpi/span.h"
+namespace wpi {
+class MulticastServiceAnnouncer {
+ public:
+  MulticastServiceAnnouncer(
+      std::string_view serviceName, std::string_view serviceType, int port,
+      wpi::span<const std::pair<std::string, std::string>> txt);
+  MulticastServiceAnnouncer(
+      std::string_view serviceName, std::string_view serviceType, int port,
+      wpi::span<const std::pair<std::string_view, std::string_view>> txt);
+  ~MulticastServiceAnnouncer() noexcept;
+  void Start();
+  void Stop();
+  bool HasImplementation() const;
+  struct Impl;
+
+ private:
+  std::unique_ptr<Impl> pImpl;
+};
+}  // namespace wpi
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef unsigned int WPI_MulticastServiceAnnouncerHandle;  // NOLINT
+
+WPI_MulticastServiceAnnouncerHandle WPI_CreateMulticastServiceAnnouncer(
+    const char* serviceName, const char* serviceType, int32_t port,
+    int32_t txtCount, const char** keys, const char** values);
+
+void WPI_FreeMulticastServiceAnnouncer(
+    WPI_MulticastServiceAnnouncerHandle handle);
+
+void WPI_StartMulticastServiceAnnouncer(
+    WPI_MulticastServiceAnnouncerHandle handle);
+
+void WPI_StopMulticastServiceAnnouncer(
+    WPI_MulticastServiceAnnouncerHandle handle);
+
+int32_t WPI_GetMulticastServiceAnnouncerHasImplementation(
+    WPI_MulticastServiceAnnouncerHandle handle);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif