[cdc_rsync] Move sockets to common (#95)

There are no real changes, just moving files around. Sockets will be
used in the future to find available ports in cdc_stream. Therefore,
they need to be in common.

common/socket.cc

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "common/socket.h"
+
+#include "common/log.h"
+#include "common/platform.h"
+#include "common/status.h"
+#include "common/util.h"
+
+#if PLATFORM_WINDOWS
+#include <winsock2.h>
+#endif
+
+namespace cdc_ft {
+
+// static
+absl::Status Socket::Initialize() {
+#if PLATFORM_WINDOWS
+  WSADATA wsaData;
+  const int result = WSAStartup(MAKEWORD(2, 2), &wsaData);
+  if (result != 0) {
+    return MakeStatus("WSAStartup() failed: %s", Util::GetWin32Error(result));
+  }
+  return absl::OkStatus();
+#elif PLATFORM_LINUX
+  return absl::OkStatus();
+#endif
+}
+
+// static
+absl::Status Socket::Shutdown() {
+#if PLATFORM_WINDOWS
+  const int result = WSACleanup();
+  if (result == SOCKET_ERROR) {
+    return MakeStatus("WSACleanup() failed: %s",
+                      Util::GetWin32Error(WSAGetLastError()));
+  }
+  return absl::OkStatus();
+#elif PLATFORM_LINUX
+  return absl::OkStatus();
+#endif
+}
+
+SocketFinalizer::~SocketFinalizer() {
+  absl::Status status = Socket::Shutdown();
+  if (!status.ok()) {
+    LOG_ERROR("Socket shutdown failed: %s", status.message())
+  }
+};
+
+}  // namespace cdc_ft