Re: [WinPcap-users] how to receive an ICMP echo reply

Tue, 08 Jul 2003 11:32:32 -0700

Because I don't use my own MAC address as sender. It's part of a bigger program. You're remark is correct, but I don't think that this causes the problems.
----- Original Message -----
Sent: Tuesday, July 08, 2003 1:07 AM
Subject: Re: [WinPcap-users] how to receive an ICMP echo reply

I just have a point to make. Why is it all that necessary using promiscous mode? If you send a packet from 1 interface, it won't come to a different interface, so promiscous mode is not necessary, it just uses more resources from what I gathered.
 
Daniel
----- Original Message -----
Sent: Monday, July 07, 2003 10:20 AM
Subject: [WinPcap-users] how to receive an ICMP echo reply

I'm trying to write something like a ping program. I send an ICMP echo request with the thread SendICMPPacket.
Sending works fine, but I'm not capable of capturing the reply and recognize it as the reply. The program captures packets, but not all the packets, how can I change that?
If somebody could check my code and give an answer why I don't capture everything and if IsICMPReply() should work.
The code is written in Visual C++ and OnBICMP is the starting point.
 
Thank u.
 
void CPIGDlg::OnBICMP()
{
 if(initAdapter()){
  //begin listening
  AfxBeginThread(ListenThread,this);
 
  Sleep(500);
 
  //send the packet
  AfxBeginThread(SendICMPPacket,this);
  Sleep(6000); //wait for listenthread to finish
 }
}
 
UINT CPIGDlg::ListenThread(LPVOID pParam)
{
 CPIGDlg * dlg = (CPIGDlg *) pParam;
 dlg->ListenThread();
 return 0;
}
 
void CPIGDlg::ListenThread()
{
 LPPACKET   lpPacket;
 char buffer[256000];
 
 if (!m_lpAdapter || (m_lpAdapter->hFile == INVALID_HANDLE_VALUE))
 {
  AfxMessageBox("Unable to open the adapter");
 } 
 
 // set the network adapter in promiscuous mode 
 if(PacketSetHwFilter(m_lpAdapter,NDIS_PACKET_TYPE_PROMISCUOUS)==FALSE){
   AfxMessageBox("Warning: unable to set promiscuous mode!");
 }
 
 // set a 512K buffer in the driver
 if(PacketSetBuff(m_lpAdapter,512000)==FALSE){
   AfxMessageBox("Unable to set the kernel buffer!");
 }
 
 // set a 1 second read timeout
 if(PacketSetReadTimeout(m_lpAdapter,1000)==FALSE){
   AfxMessageBox("Warning: unable to set the read timeout!");
 }
 
 //allocate and initialize a packet structure that will be used to
 //receive the packets.
 if((lpPacket = PacketAllocatePacket())==NULL){
  AfxMessageBox("Error: failed to allocate the LPPACKET structure.");
 }
 PacketInitPacket(lpPacket,(char*)buffer,256000);
 
 //main capture loop
 while(true)
 {
     // capture the packets
  if(PacketReceivePacket(m_lpAdapter,lpPacket,TRUE)==FALSE){
   MessageBox("Error: PacketReceivePacket failed");
  }
  else{
   if(lpPacket->ulBytesReceived!=0){
    AfxMessageBox("packet captured");
    (void)IsICMPReply(lpPacket);
   }
  }
 }
 
 PacketFreePacket(lpPacket);
 
 // close the adapter and exit
 PacketCloseAdapter(m_lpAdapter);
}
 
BOOL CPIGDlg::IsICMPReply(LPPACKET lpPacket)
{
 BOOL bFlag = FALSE;
 PIPHEADER pIPHeader;
 PICMPPACKET pICMPPacket; 
 char *buf;
 u_int off=0;
 struct bpf_hdr *hdr;
 
 buf = (char*)lpPacket->Buffer;
 off=0;
 hdr=(struct bpf_hdr *)(buf+off);
 off+=hdr->bh_hdrlen;
 
 pICMPPacket = (PICMPPACKET) (buf + off);  //cast the received lpPacket to a ICMPPacket
 
 if (pICMPPacket->ehhdr.eh_type == htons(0x0800)){     //if the ethernet type = IP, can be icmp
  if (strcmp((char*)(pICMPPacket->ehhdr.eh_dmac),m_myMAC) == 0
   && pICMPPacket->icmphead.i_id == (USHORT)GetCurrentProcessId())    //if m_myMac = destination MAC and id = current process id
  {
   char szTemp[10];
   pIPHeader = (PIPHEADER)(buf + off + sizeof(EHHDR));
   memcpy(szTemp, &pIPHeader->sourceIP, sizeof(pIPHeader->sourceIP));
   AfxMessageBox((char*)inet_ntoa(*((struct in_addr *)(szTemp))));
   return TRUE;
  }
 }
 return FALSE;
}

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