Neal, Thomas, what do you think about the patch? Your knowledge of the
Windows API is greater than mine. Is the duplicate_socket() function ok?
I don't want to apply a patch I don't fully understand.

+#ifdef MS_WINDOWS
+/* On Windows a socket is really a handle not an fd */
+static SOCKET
+duplicate_socket(SOCKET handle)
+{
+       HANDLE newhandle;
+
+       if (!DuplicateHandle(GetCurrentProcess(), (HANDLE)handle,
+                            GetCurrentProcess(), &newhandle,
+                            0, FALSE, DUPLICATE_SAME_ACCESS))
+       {
+               WSASetLastError(WSAEBADF);
+               return INVALID_SOCKET;
+       }
+       return (SOCKET)newhandle;
+}
+#define dup(fd) duplicate_socket(fd)
+#define SOCKETCLOSE closesocket
+#define NO_MAKEFILE /* socket handles can't be treated like file handles */
+#endif