[Winpcap-users] Not able to capture IPv6 packets.

[Bassam A. Al-Khaffaf]

Dear all,

   I am writing a radius server using winsock2 with win32 C++ on visual C++
2005 express edition on windows xp pro. The application supports both IPv4
and IPv6 and I want to extract the source and destination MAC and IP
addresses from the incoming packets.

 

However, I have read the winpcap documentation and learened on how to sniff
the MACs and IPs. Unfortunately, my sniffer is able to capture the IPv4
only, while I would like to have both IPv4 and IPv6 are captured, a portion
code snippet is shown below.

 

I don't know what is the wrong in my code, and I would appreciate if you
helped me to solve this problem.

 

Regards

Bassam

 

 

 

#include <iostream>

using std::cout;

using std::cin;

using std::cerr;

using std::endl;

 

#include <winsock2.h>

#include "pcap.h"

 

int getAdapters(void)

{

    pcap_if_t *alldevs;

    pcap_if_t *d;

      pcap_t *adhandle;

    int inum, i=0, res;

    char errbuf[PCAP_ERRBUF_SIZE];

      struct tm *ltime;

      char timestr[16];

      struct pcap_pkthdr *header;

      const u_char *pkt_data;

      time_t local_tv_sec;

      struct bpf_program fcode;

      u_int netmask;

 

    

    /* Retrieve the device list from the local machine */

    //if (pcap_findalldevs(&alldevs, errbuf) == -1)

      if (pcap_findalldevs_ex(PCAP_SRC_IF_STRING, NULL, &alldevs, errbuf) ==
-1)

    {

        cerr << "Error in pcap_findalldevs_ex: " << errbuf << endl;

        exit(1);

    }

    

    /* Print the list */

    for(d= alldevs; d != NULL; d= d->next)

    {

        cout << ++i << "." << d->name << " ";

        if (d->description)

            cout << d->description << endl;

        else

            cout << "(No description available)" << endl;

    }

    

    if (i == 0)

    {

        cout << "\nNo interfaces found! Make sure WinPcap is installed." <<
endl;

        return -1;

    }

    

 

      cout << "\nEnter the interface number: " << endl;

      cin >> inum;

 

      if (inum < 1 || inum > i)

      {

            cout << "\nInterface number out of range." << endl;

            

            /* Free the device list */

            pcap_freealldevs(alldevs);

            return -1;

      }

       

      /* Jump to the selected adapter */

      for(d=alldevs, i=0; i< inum-1 ;d=d->next, i++);

 

            

      /* Open the device */

      if ((adhandle= pcap_open(d->name, 65535 , 0, 1000, NULL, errbuf)) ==
NULL)

      {

            cerr << "\nUnable to open the adapter. " << d->name << " is not
supported by WinPcap" << endl;

 

            /* Free the device list */

            pcap_freealldevs(alldevs);

            return -1;

      }

      

 

    if (d->addresses != NULL)

        /* Retrieve the mask of the first address of the interface */

        netmask=((struct sockaddr_in
*)(d->addresses->netmask))->sin_addr.S_un.S_addr;

    else

        /* If the interface is without an address we suppose to be in a C
class network */

        netmask=0xffffff; 

 

 

    //compile the filter

    if (pcap_compile(adhandle, &fcode, "udp dst port 1812 or dst port 1813",
1, 0) < 0)

    {

        fprintf(stderr,"\nUnable to compile the packet filter. Check the
syntax.\n");

        /* Free the device list */

        pcap_freealldevs(alldevs);

        return -1;

    }

    

    //set the filter

    if (pcap_setfilter(adhandle, &fcode) < 0)

    {

        cerr << "\nError setting the filter." << endl;

        /* Free the device list */

        pcap_freealldevs(alldevs);

        return -1;

    }

       

      cout << "\nlistening on " << d->description << endl;

 

      /* At this point, we don't need any more the device list. Free it */

      pcap_freealldevs(alldevs);

 

 

      /* Retrieve the packets */

      while((res = pcap_next_ex(adhandle, &header, &pkt_data)) >= 0)

      {

 

            if(res == 0)

                  continue;   /* Timeout elapsed */

 

            if(res == -1)

            {

                  cout << "Error reading the packets: " <<
pcap_geterr(adhandle) << endl;

                  return -1;

            }

            

            /* convert the timestamp to readable format */

            local_tv_sec = header->ts.tv_sec;

            ltime=localtime(&local_tv_sec);

            strftime( timestr, sizeof timestr, "%H:%M:%S", ltime);

 

            cout << timestr << "." << header->ts.tv_usec << "len: " <<
header->len <<  endl;

 

            cout << "Packet Data: " << endl;

            for (i = 0; i < 34; i++)

                  cout << static_cast<int>(pkt_data[i]) << " ";

 

            cout << endl;

      }

      

      return 0;

}

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