[wpinet] Move network portions of wpiutil into new wpinet library (#4077)

wpinet/src/main/native/macOS/MulticastServiceAnnouncer.cpp

@@ -0,0 +1,86 @@
+// 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.
+
+#include "wpinet/MulticastServiceAnnouncer.h"
+
+#include <wpi/SmallString.h>
+
+#include "dns_sd.h"
+
+using namespace wpi;
+
+struct MulticastServiceAnnouncer::Impl {
+  std::string serviceName;
+  std::string serviceType;
+  int port;
+  DNSServiceRef serviceRef{nullptr};
+  TXTRecordRef txtRecord;
+
+  Impl() { TXTRecordCreate(&txtRecord, 0, nullptr); }
+
+  ~Impl() noexcept { TXTRecordDeallocate(&txtRecord); }
+};
+
+MulticastServiceAnnouncer::MulticastServiceAnnouncer(
+    std::string_view serviceName, std::string_view serviceType, int port,
+    wpi::span<const std::pair<std::string, std::string>> txt) {
+  pImpl = std::make_unique<Impl>();
+  pImpl->serviceName = serviceName;
+  pImpl->serviceType = serviceType;
+  pImpl->port = port;
+
+  for (auto&& i : txt) {
+    TXTRecordSetValue(&pImpl->txtRecord, i.first.c_str(), i.second.length(),
+                      i.second.c_str());
+  }
+}
+
+MulticastServiceAnnouncer::MulticastServiceAnnouncer(
+    std::string_view serviceName, std::string_view serviceType, int port,
+    wpi::span<const std::pair<std::string_view, std::string_view>> txt) {
+  pImpl = std::make_unique<Impl>();
+  pImpl->serviceName = serviceName;
+  pImpl->serviceType = serviceType;
+  pImpl->port = port;
+
+  wpi::SmallString<64> key;
+
+  for (auto&& i : txt) {
+    key.clear();
+    key.append(i.first);
+    key.emplace_back('\0');
+
+    TXTRecordSetValue(&pImpl->txtRecord, key.data(), i.second.length(),
+                      i.second.data());
+  }
+}
+
+MulticastServiceAnnouncer::~MulticastServiceAnnouncer() noexcept {
+  Stop();
+}
+
+bool MulticastServiceAnnouncer::HasImplementation() const {
+  return true;
+}
+
+void MulticastServiceAnnouncer::Start() {
+  if (pImpl->serviceRef) {
+    return;
+  }
+
+  uint16_t len = TXTRecordGetLength(&pImpl->txtRecord);
+  const void* ptr = TXTRecordGetBytesPtr(&pImpl->txtRecord);
+
+  (void)DNSServiceRegister(&pImpl->serviceRef, 0, 0, pImpl->serviceName.c_str(),
+                           pImpl->serviceType.c_str(), "local", nullptr,
+                           htons(pImpl->port), len, ptr, nullptr, nullptr);
+}
+
+void MulticastServiceAnnouncer::Stop() {
+  if (!pImpl->serviceRef) {
+    return;
+  }
+  DNSServiceRefDeallocate(pImpl->serviceRef);
+  pImpl->serviceRef = nullptr;
+}