SPI的WSPSendto（）函数中怎么解析出源IP

[guyuan123]

我在SPI中写了个WSPSendto（）函数，
我想在函数中获得发出数据包的源IP和目的IP
然后用源IP和本地IP（用gethostbyname获取的）比较
看看此包中的IP是否为发包程序伪造的，
问题来了：怎么在WSPSendto（）中获得数据包中的源IP
int WSPAPI WSPSendTo(
SOCKET s,
LPWSABUF lpBuffers,
DWORD dwBufferCount,
LPDWORD lpNumberOfBytesSent,
DWORD dwFlags,
const struct sockaddr FAR * lpTo,
int iTolen,
LPWSAOVERLAPPED lpOverlapped,
LPWSAOVERLAPPED_COMPLETION_ROUTINE lpCompletionRoutine,
LPWSATHREADID lpThreadId,
LPINT lpErrno
)
{
ODS1(L"%s试图发包", g_szCurrentApp);
SOCKADDR_IN sa = *(SOCKADDR_IN*)lpTo;
sa.sin_addr.S_un；//其中存的是目的IP
？？ ？？？ //怎么获得数据包中的源IP，
//以便和真实IP比较
if(数据包中的源IP！=gethostbyname获得的本地真实IP)
{
int iError;
g_NextProcTable.lpWSPShutdown(s, SD_BOTH, &iError);
*lpErrno = WSAECONNABORTED;

ODS(L" deny a sendto ");
return SOCKET_ERROR;
}*/

return g_NextProcTable.lpWSPSendTo(s, lpBuffers, dwBufferCount, lpNumberOfBytesSent, dwFlags, lpTo
, iTolen, lpOverlapped, lpCompletionRoutine, lpThreadId, lpErrno);

}

[guyuan123]

//上文中这个地方是如果判断了是非法包的话，阻止其发出
{
int iError;
g_NextProcTable.lpWSPShutdown(s, SD_BOTH, &iError);
*lpErrno = WSAECONNABORTED;
ODS(L" deny a sendto ");
return SOCKET_ERROR;
}