Problem capturing packets over the LAN using ICAP
Hi. I'm having a problem in my code to capture packets over the LAN using ICAP library. Apparently there doesn't seem to be any problem, but whenever I run the code, it gives to list of the devices (which is indeed required) but when I enter the device number, it says: "Segmentation fault". I don't understand what's the problem. Can anyone help? Here's the code:
Code:
int main(int argc, char **argv)
{
char errbuf[PCAP_ERRBUF_SIZE];
pcap_t* descr;
const u_char *packet;
struct pcap_pkthdr hdr; /* pcap.h */
struct ether_header *eptr; /* net/ethernet.h */
u_char *ptr; /* printing out hardware header info */
/* grab a device to peak into... */
/* dev = pcap_lookupdev(errbuf);
if(dev == NULL)
{
printf("%s\n",errbuf);
exit(1);
}
printf("DEV: %s\n",dev);*/
///////////////////////////////////////////////////////////////////////////////////////////////////////////
pcap_if_t *alldevs;
pcap_if_t *d;
int i=0;
pcap_t * fp;
if (pcap_findalldevs(&alldevs, errbuf) == -1)
{
cout<<"Error in pcap_findalldevs "<<errbuf;
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)\n";
}
if (i == 0)
{
cout<<"\nNo interfaces found! Make sure Pcap is installed.\n";
return 1;
}
cout<<"Enter the interface number"<< (1-i);
int inum;
cin>>inum;
if(inum < 1 || inum > i)
{
cout<<"\nInterface number out of range.\n";
// Free the device list /
pcap_freealldevs(alldevs);
return 1;
}
char *dev=d->name;
////////////////////////////////////////////////////////////////////////////////////////////////////
cout<<"adada"<<endl;
descr = pcap_open_live(dev,65536,1,0,errbuf);
if(descr == NULL)
{
printf("pcap_open_live(): %s\n",errbuf);
exit(1);
}
struct pcap_pkthdr;
packet = pcap_next(descr,&hdr);
if(packet == NULL)
{
printf("Didn't grab packet\n");
exit(1);
}
printf("Grabbed packet of length %d\n",hdr.len);
printf("Recieved at ..... %s\n",ctime((const time_t*)&hdr.ts.tv_sec));
printf("Ethernet address length is %d\n",ETHER_HDR_LEN);
eptr = (struct ether_header *) packet;
if (ntohs (eptr->ether_type) == ETHERTYPE_IP)
{
printf("Ethernet type hex:%x dec:%d is an IP packet\n",
ntohs(eptr->ether_type),
ntohs(eptr->ether_type));
}else if (ntohs (eptr->ether_type) == ETHERTYPE_ARP)
{
printf("Ethernet type hex:%x dec:%d is an ARP packet\n",
ntohs(eptr->ether_type),
ntohs(eptr->ether_type));
}else {
printf("Ethernet type %x not IP", ntohs(eptr->ether_type));
exit(1);
}
ptr = eptr->ether_dhost;
i = ETHER_ADDR_LEN;
printf(" Destination Address: ");
do{
printf("%s%x",(i == ETHER_ADDR_LEN) ? " " : ":",*ptr++);
}while(--i>0);
printf("\n");
ptr = eptr->ether_shost;
i = ETHER_ADDR_LEN;
printf(" Source Address: ");
do{
printf("%s%x",(i == ETHER_ADDR_LEN) ? " " : ":",*ptr++);
}while(--i>0);
printf("\n");
return 0;
}
