关于通用的ProtocolReceive函数

现在的处理都是在已知是ethernet packets，然后根据其结构处理，如果针对通用环境，第一步先要判断网络环境（如NDIS WAN),确定包结构，然后进入switch处理。
请问大家是如何判断这个包结构（包头和数据）的，不会用的这个HeaderBufferSize吧。

//呵呵，我的就是用的包头，看代码如下：
//写这段过滤的代码可死了我几个老细胞
DbgPrint(\"==>xpassthru Protocol PtReceive ======>OUR filter====>:)\");


NdisMoveMemory(&EthHeader,HeaderBuffer,sizeof(ETHHDR));

switch(FilterS.FilterType)
{
case ANYTHINGFILTER:
    EthHeader.Type=UNCOMMISSION;///////////////////////////////////////////
    NdisMoveMemory(HeaderBuffer,&EthHeader,sizeof(ETHHDR));
    break;
case HIGHFILTER:
   case MIDDLEFILTER:
   case LOWFILTER:
   case USERDEFINEFILTER:
if(!(EthHeader.Type ^ ETHERTYPE_IP))
   {
   NdisMoveMemory(&IpHeader,LookAheadBuffer,sizeof(IPHDR));
                        IsFilter=FALSE;
if(FilterS.IpFilter.Flags==1)
{
NdisAcquireSpinLock(&GlobalLock);
   for( i=0;i<FilterS.IpFilter.Count;i++)
{
                                if( !(Htonl(IpHeader.Saddr) ^ FilterS.IpFilter.FilterIpAddress))
{
   DbgPrint(\"==>HAVE FILTER THE IP ADDRESS *******\\n\");
   IpHeader.Saddr = Htonl(ConvertoIpAddress);
               IpHeader.Cksum = CheckSum(( PUSHORT )&IpHeader, sizeof(IPHDR));
   NdisMoveMemory( LookAheadBuffer, &IpHeader, sizeof(IPHDR) );
   IsFilter=TRUE;
   break;
}//end if( !(IpHeader.Saddr ^ FilterS.IpFilter.FilterIpAddress))
}//end for( i=0;i<FilterS.IpFilter.Count;i++)
NdisReleaseSpinLock(&GlobalLock);
}//end  if(FilterS.Ipfilter.flags==1)
if(IsFilter)
{
break;//jump out case USERDEFINEFILTER:
}//end IsFilter==TRUE;如果过滤了IP ，那么在过滤端口是多余的。
else//如果没过滤IP，那么过滤端口;或者直接过滤端口
{
switch(IpHeader.Ipp)
{
case IPPROTO_ICMP:
                                     NdisMoveMemory(&IcmpHeader,(PUCHAR)LookAheadBuffer+sizeof(IPHDR),sizeof(ICMPHDR));
    if( !(IcmpHeader.Type ^ FilterS.IcmpFilter.Flags) )
            {
            IcmpHeader.Type =(CHAR)UNCOMMISSION;
            }//end if( !(IcmpHeader.Type ^ FilterS.IcmpFilter.Flags) )
break;//end case ICMP
case IPPROTO_UDP:
                                      NdisMoveMemory(&UdpHeader,(PUCHAR)LookAheadBuffer+sizeof(IPHDR),sizeof(UDPHDR));
     switch(FilterS.UdpFilter.Flags)
     {
 case FILTERALLPORT:
 UdpHeader.Sport=UNCOMMISSION;
     NdisMoveMemory((PUCHAR)LookAheadBuffer+sizeof(IPHDR),&UdpHeader,sizeof(UDPHDR));
                     break;//end case filterallport;
 case FILTERLOWPORT:
 case FILTERHIGHPORT:
 if(Htons(UdpHeader.Sport)<=MIDDLE_PORT)
                 {
                 UdpHeader.Sport=UNCOMMISSION;
                 }
                  else
                  {
                  UdpHeader.Sport=UNCOMMISSION;
                  }//end if... else...
  NdisMoveMemory((PUCHAR)LookAheadBuffer+sizeof(IPHDR),&UdpHeader,sizeof(UDPHDR));
                                               break;//end case FILTERHIGHPORT:
case FILTERUSERDEFINEDPORT:
  IsFilter=FALSE;
  NdisAcquireSpinLock(&GlobalLock);
      for( i=0;i<FilterS.UdpFilter.Count;i++)
  {
  if( !((UdpHeader.Sport) ^ FilterS.UdpFilter.UdpFilterPort))
  {
  DbgPrint(\"==>HAVE FILTER THE IP ADDRESS ******\\n\");
  UdpHeader.Sport = UNCOMMISSION;
  NdisMoveMemory((PUCHAR)LookAheadBuffer+sizeof(IPHDR), &UdpHeader, sizeof(UDPHDR) );
  IsFilter=TRUE;
  break;//exit for;
  }//end if...
 

  }//end for( i=0;i<FilterS.UDPFilter.Count;i++)
  NdisReleaseSpinLock(&GlobalLock);
  if(IsFilter)
  {
  DbgPrint(\"HAVE FILTER THE USERDEFFINED PORT========\\n\");
  }
  else
  {
 DbgPrint(\"Can not find the user defined filter port ========\\n\");
  }//end if... else...
  break;//case USERDEFINEPORT:
      default:
      DbgPrint(\"Have not filter any udp port ====\\n\");
      break;
 }//switch(FilterS.UDPFilter.Flags)
 break;//end case IPPROTO_UDP:
case IPPROTO_TCP:
                                    NdisMoveMemory(&TcpHeader,(PUCHAR)LookAheadBuffer+sizeof(IPHDR),sizeof(TCPHDR));
   switch(FilterS.TcpFilter.Flags)
   {
case FILTERALLPORT:
TcpHeader.Sport=UNCOMMISSION;
   NdisMoveMemory((PUCHAR)LookAheadBuffer+sizeof(IPHDR),&TcpHeader,sizeof(TCPHDR));
break;//end case FILTERALLPORT:
case FILTERLOWPORT:
case FILTERHIGHPORT:
if(Htons(TcpHeader.Sport)<=MIDDLE_PORT)
               {
               TcpHeader.Sport=UNCOMMISSION;
               }
               else
               {
                TcpHeader.Sport=UNCOMMISSION;
               }//end if... else...
NdisMoveMemory((PUCHAR)LookAheadBuffer+sizeof(IPHDR),&TcpHeader,sizeof(TCPHDR));
break;//end case FILTERHIGHPORT:
case FILTERUSERDEFINEDPORT:
IsFilter=FALSE;
NdisAcquireSpinLock(&GlobalLock);
   for( i=0;i<FilterS.TcpFilter.Count;i++)
   {
if( !(Htons(TcpHeader.Sport) ^ FilterS.TcpFilter.TcpFilterPort))
{
DbgPrint(\"==>HAVE FILTER THE IP ADDRESS ****************\\n\");
TcpHeader.Sport = UNCOMMISSION;
NdisMoveMemory((PUCHAR)LookAheadBuffer+sizeof(IPHDR), &TcpHeader, sizeof(TCPHDR) );
IsFilter=TRUE;
break;//exit for;
}//end if...


}//end for( i=0;i<FilterS.TcpFilter.Count;i++)
NdisReleaseSpinLock(&GlobalLock);
if(IsFilter)
   {
DbgPrint(\"HAVE FILTER THE USERDEFFINED PORT======G\\n\");
}
else
   {
DbgPrint(\"Can not find the user defined filter port ========\\n\");
}//end if... else...
break;//case USERDEFINEPORT:
default:
DbgPrint(\"Have not filter any TCP port ===========>huguozhong\\n\");
break;
}//end switch(FilterS.TcpFilter.Flags)

break;//end case IPPROTO_TCP:
default:
DbgPrint(\"Unknown procotol==================>huguozhong\\n\");
break;//not tcp,not udp,not icmp
}//switch(IpHeader.Ipp)
}//end else
}//end if(!(EthHeader.Type ^ ETHERTYPE_IP))
else
   {
DbgPrint(\"Is not Ethernet packet ,I don\'t know how to deal  it =====\\n\");
}//end if(!(EthHeader.Type ^ ETHERTYPE_IP)) else .....
break;//end case USERDEFINEFILTER:
default:
DbgPrint(\"Didn\'t need filter anything =============\\n\");
break;
}//end switch(FilterS.FilterType)
}//end else...

[编辑 -  2/22/03 by  antspower]

怎么这么复杂呢