高分求解：Delphi编程如何知道硬件网关的WAN IP呢？(100分)

局域网通过硬件网关上网，想在局域网中知道当前的WAN IP，不知道用DELPHI如何实现?

procedure TForm1.Button1Click(Sender: TObject);
var
wVersionRequested : WORD;
wsaData : TWSAData;
p : PHostEnt;
s : array[0..128] of char;
p2 : pchar;
hostName,hostIP:String;
begin
{Start up WinSock}
wVersionRequested := MAKEWORD(1, 1);
WSAStartup(wVersionRequested, wsaData);

{Get the computer name}
GetHostName(@s, 128);
p := GetHostByName(@s);

{Get the IpAddress}
p2 := iNet_ntoa(PInAddr(p^.h_addr_list^)^);

hostName:=p^.h_Name;
hostIP:=p2;
showmessage(hostname+hostip);
WSACleanup;
end;

tracert

执行
WSAStartup(wVersionRequested, wsaData);
发生如下错误：
Project Project1.exe raised exception class EAccessViolation with message 'Access violation at address 00000000. Read of address 00000000'. Process stopped. Use Step or Run to continue.