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

wpinet/src/main/native/cpp/SocketError.cpp

@@ -0,0 +1,37 @@
+// 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/SocketError.h"
+
+#ifdef _WIN32
+#include <winsock2.h>
+#else
+#include <cerrno>
+#include <cstring>
+#endif
+
+namespace wpi {
+
+int SocketErrno() {
+#ifdef _WIN32
+  return WSAGetLastError();
+#else
+  return errno;
+#endif
+}
+
+std::string SocketStrerror(int code) {
+#ifdef _WIN32
+  LPSTR errstr = nullptr;
+  FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, 0,
+                code, 0, (LPSTR)&errstr, 0, 0);
+  std::string rv(errstr);
+  LocalFree(errstr);
+  return rv;
+#else
+  return std::strerror(code);
+#endif
+}
+
+}  // namespace wpi