使用重叠IO处理UDP接收的时候，WSARecvFrom返回10014的错误。请高手指教

Question

代码如下
function iniSocket: Boolean;
var
    wsaData: TWSAData;
begin
    result := false;
    if (sock <> INVALID_SOCKET) then exit;
    if (WSAStartup(MAKEWORD(2, 2), wsaData) <> 0) then exit;
    sock := WSASocket(AF_INET, SOCK_DGRAM, IPPROTO_UDP, nil, 0, WSA_FLAG_OVERLAPPED);
    ServerAddr.sin_family := AF_INET;
    ServerAddr.sin_port := htons(SERVER_PORT);
    ServerAddr.sin_addr.S_addr :=INADDR_ANY;
    if winsock.bind(sock, ServerAddr, SizeOf(ServerAddr)) = SOCKET_ERROR then
    begin
        closesocket(sock);
        sock := INVALID_SOCKET;
        exit;
    end;
    FillChar(over_lap,SizeOf(WSAOVERLAPPED),0);
    over_lap.hEvent:=WSACreateEvent;    result := True;
end;
function p2pserver(): bool;
var
    //std:_stShowThreadData;
    intRet:integer;
    dwRecv,dwFlags:Cardinal;
    pwsa_BUF:PWSABUF;
    remoteaddr:sockaddr_in;
    threadhandle,threadid:Cardinal;
    iErr,inaddlen:Integer;
    pmsg:^_stMessage;
begin
    if not iniSocket then exit;
    New(pmsg);
    New(pwsa_BUF);
    pwsa_BUF^.buf:=nil;
    pwsa_BUF^.len:=MAX_PACKET_SIZE;
    inaddlen:=SizeOf(remoteaddr);
    clientList := tlist.Create;
    Form1.Memo1.Lines.Add('服务器启动');
    if Form1.CheckBox1.Checked then
    begin
        threadhandle := CreateThread(nil, 0, @keepalive, nil, 0, threadid);
        CloseHandle(threadhandle);
    end;
    while(True) do
    begin
      dwRecv:=0;
      dwFlags:=0;
      intRet:=WSARecvFrom(sock,pwsa_BUF,1,@dwRecv,@dwFlags,@remoteaddr,@inaddlen,@over_lap,nil);
      iErr:=WSAGetLastError;//总是返回10014，地址错？
      if (intRet=SOCKET_ERROR) and (iErr=WSA_IO_PENDING) then
      begin
        WSAGetOverlappedResult(sock,@over_lap,@dwRecv,True,@dwFlags);
      end;
      if SERVER_OUT then break;
      pmsg:=pwsa_BUF^.buf;
      if dwRecv>0 then 
        HandleIO(pmsg^,dwRecv,remoteaddr);
    end;
    WSACloseEvent(over_lap.hEvent);
    Dispose(pmsg);
    Dispose(pwsa_BUF);
    WSACleanup();
    result := True;
end;

Answer 1

pwsa_buf.buf指针不能为nil，必须指向一块分配好的内存。
pwsa_Buf.buf=Allocmem(MAX_PACKET_SIZE);