Get a list of devices

In general, the first thing to write a WinPcap-based application is to get a list of connected network adapters. Both Libpcap and WinPcap provide the PCAP_FINDALLDEVS_EX () function to implement this function: This function returns a list of pcap_if structures, each of which contains the details of an adapter. It is important to note that the data field name and description represent an adapter name and a description that people can understand.

The following code can get the list of adapters and display them on the screen, and if the adapter is not found, an error message will be printed.

#include   "Pcap.h" main () {    pcap_if_t *alldevs;    pcap_if_t  *d;    int i=0;    char errbuf[PCAP_ERRBUF_SIZE];         /*  get a list of local machine devices  */    if  ( PCAP_FINDALLDEVS_EX (pcap_src_if_string, null /* auth is not needed */,  &ALLDEVS, ERRBUF)  == -1)     {         fprintf (stderr, "error in pcap_findalldevs_ex: %s\n",  errbuf);         exit (1);    }         /*  Print List  */    for (d= alldevs; d != null; d=  d->next)     {        printf ("%d. %s" ,  ++i, d->name);         if  (d->description)              printf ("  (%s) \ n",  d->description);         else            printf ("   (no description available) \ n ");    }         if  (i == 0)     {         printf ("\nno interfaces found! make sure winpcap is installed.\n");         return;    }    /*   no longer requires a list of devices, release it  */    pcap_freealldevs (Alldevs);}

A few notes about this piece of code

First, PCAP_FINDALLDEVS_EX (), like the other Libpcap functions, has a errbuf parameter. Once an error occurs, this parameter is Libpcap written to the string type error message.

Second, remember that not all operating systems support the LIBPCAP provided by the network program interface, so if we want to write a portable application, we have to consider under what circumstances, description is null. In this program, when we encounter this situation, the prompt statement "No description available" is printed.

Finally remember that when we complete the device list of the Make

We are going to call the Pcap_freealldevs () function to release the memory resources it occupies.

The result we get is:

1. \device\npf_{4e273621-5161-46c8-895a-48d0e52a0b83} (Realtek RTL8029 (AS) Ethernet Adapter) 2. \device\npf_{5d24ae04-c486-4a96-83fb-8b5ec6c7f430} (3Com EtherLink PCI)

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Get a list of devices