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

wpiutil/src/main/native/cpp/MulticastServiceResolver.cpp

@@ -0,0 +1,134 @@
+// 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 "wpi/MulticastServiceResolver.h"
+
+#include "MulticastHandleManager.h"
+#include "wpi/MemAlloc.h"
+
+extern "C" {
+WPI_MulticastServiceResolverHandle WPI_CreateMulticastServiceResolver(
+    const char* serviceType)
+
+{
+  auto& manager = wpi::GetMulticastManager();
+  std::scoped_lock lock{manager.mutex};
+
+  auto resolver = std::make_unique<wpi::MulticastServiceResolver>(serviceType);
+
+  size_t index = manager.handleIds.emplace_back(2);
+  manager.resolvers[index] = std::move(resolver);
+
+  return index;
+}
+
+void WPI_FreeMulticastServiceResolver(
+    WPI_MulticastServiceResolverHandle handle) {
+  auto& manager = wpi::GetMulticastManager();
+  std::scoped_lock lock{manager.mutex};
+  manager.resolvers[handle] = nullptr;
+  manager.handleIds.erase(handle);
+}
+
+void WPI_StartMulticastServiceResolver(
+    WPI_MulticastServiceResolverHandle handle) {
+  auto& manager = wpi::GetMulticastManager();
+  std::scoped_lock lock{manager.mutex};
+  auto& resolver = manager.resolvers[handle];
+  resolver->Start();
+}
+
+void WPI_StopMulticastServiceResolver(
+    WPI_MulticastServiceResolverHandle handle) {
+  auto& manager = wpi::GetMulticastManager();
+  std::scoped_lock lock{manager.mutex};
+  auto& resolver = manager.resolvers[handle];
+  resolver->Stop();
+}
+
+int32_t WPI_GetMulticastServiceResolverHasImplementation(
+    WPI_MulticastServiceResolverHandle handle) {
+  auto& manager = wpi::GetMulticastManager();
+  std::scoped_lock lock{manager.mutex};
+  auto& resolver = manager.resolvers[handle];
+  return resolver->HasImplementation();
+}
+
+WPI_EventHandle WPI_GetMulticastServiceResolverEventHandle(
+    WPI_MulticastServiceResolverHandle handle) {
+  auto& manager = wpi::GetMulticastManager();
+  std::scoped_lock lock{manager.mutex};
+  auto& resolver = manager.resolvers[handle];
+  return resolver->GetEventHandle();
+}
+
+WPI_ServiceData* WPI_GetMulticastServiceResolverData(
+    WPI_MulticastServiceResolverHandle handle) {
+  wpi::MulticastServiceResolver::ServiceData data;
+  {
+    auto& manager = wpi::GetMulticastManager();
+    std::scoped_lock lock{manager.mutex};
+    auto& resolver = manager.resolvers[handle];
+    data = resolver->GetData();
+  }
+  size_t allocSize = sizeof(WPI_ServiceData);
+  // Include space for hostName and serviceType (+ terminators)
+  allocSize += data.hostName.size() + data.serviceName.size() + 2;
+
+  size_t keysTotalLength = 0;
+  size_t valuesTotalLength = 0;
+  // Include space for all keys and values, and pointer array
+  for (auto&& t : data.txt) {
+    allocSize += sizeof(const char*);
+    keysTotalLength += (t.first.size() + 1);
+    allocSize += sizeof(const char*);
+    valuesTotalLength += (t.second.size() + 1);
+  }
+  allocSize += keysTotalLength;
+  allocSize += valuesTotalLength;
+  uint8_t* cDataRaw = reinterpret_cast<uint8_t*>(wpi::safe_malloc(allocSize));
+  if (!cDataRaw) {
+    return nullptr;
+  }
+  WPI_ServiceData* cData = reinterpret_cast<WPI_ServiceData*>(cDataRaw);
+  cData->ipv4Address = data.ipv4Address;
+  cData->port = data.port;
+  cData->txtCount = data.txt.size();
+  cDataRaw += sizeof(WPI_ServiceData);
+
+  std::memcpy(cDataRaw, data.hostName.c_str(), data.hostName.size() + 1);
+  cData->hostName = reinterpret_cast<const char*>(cDataRaw);
+  cDataRaw += data.hostName.size() + 1;
+
+  std::memcpy(cDataRaw, data.serviceName.c_str(), data.serviceName.size() + 1);
+  cData->serviceName = reinterpret_cast<const char*>(cDataRaw);
+  cDataRaw += data.serviceName.size() + 1;
+
+  char** valuesPtrArr = reinterpret_cast<char**>(cDataRaw);
+  cDataRaw += (sizeof(char**) * data.txt.size());
+  char** keysPtrArr = reinterpret_cast<char**>(cDataRaw);
+  cDataRaw += (sizeof(char**) * data.txt.size());
+
+  cData->txtKeys = const_cast<const char**>(keysPtrArr);
+  cData->txtValues = const_cast<const char**>(valuesPtrArr);
+
+  for (size_t i = 0; i < data.txt.size(); i++) {
+    keysPtrArr[i] = reinterpret_cast<char*>(cDataRaw);
+    std::memcpy(keysPtrArr[i], data.txt[i].first.c_str(),
+                data.txt[i].first.size() + 1);
+    cDataRaw += (data.txt[i].first.size() + 1);
+
+    valuesPtrArr[i] = reinterpret_cast<char*>(cDataRaw);
+    std::memcpy(valuesPtrArr[i], data.txt[i].second.c_str(),
+                data.txt[i].second.size() + 1);
+    cDataRaw += (data.txt[i].second.size() + 1);
+  }
+
+  return cData;
+}
+
+void WPI_FreeServiceData(WPI_ServiceData* serviceData) {
+  std::free(serviceData);
+}
+}  // extern "C"