下面这段代码的具体实现过程是什么？tcp包的拆分过程？思想流程，尽量详细些，谢谢！

if (LPIPHEADER->byProtocol == IPPROTO_TCP)
{
TCPHEADER = (LPTCP_HDR)&szBuffer[(LPIPHEADER->byVerLen & 0x0F)*4];
if (ntohs(TCPHEADER->wSrcPort) == 1863 ||
ntohs(TCPHEADER->wDestPort) == 1863)
{
nHeaderLen = (LPIPHEADER->byVerLen & 0x0F)*4 +
(ntohs(TCPHEADER->wLenFlag) >> 12) * 4;

lpData = (LPCSTR)&szBuffer[nHeaderLen] ;

if (strstr(lpData, "MSG") &&
strstr(lpData, "text/plain"))
{
nWLen = LdapUTF8ToUnicode(lpData,
nDataLen - nHeaderLen,
(LPWSTR)szData,
sizeof(szData));
WideCharToMultiByte(CP_ACP,
WC_COMPOSITECHECK,
szData,
nWLen,
szBuffer,
sizeof(szBuffer),
NULL,
NULL);
int nSize = GetWindowTextLength(hBox) + strlen(szBuffer) + 1;
pBuffer = (char*)malloc(nSize);