pcap_list_datalinks, pcap_free_datalinks - get a list of link-layer header types
supported by a capture device, and free that list
int pcap_list_datalinks(pcap_t *p, int **dlt_buf);
void pcap_free_datalinks(int *dlt_list);
pcap_list_datalinks() is used to get a list of the supported link-layer
header types of the interface associated with the pcap descriptor.
pcap_list_datalinks() allocates an array to hold the list and sets
*dlt_buf to point to that array.
The caller is responsible for freeing the array with
pcap_free_datalinks(), which frees the list of link-layer header
types pointed to by dlt_list.
It must not be called on a pcap descriptor created by
pcap_create(3PCAP) that has not yet been activated by
pcap_list_datalinks() returns the number of link-layer header types in
the array on success, PCAP_ERROR_NOT_ACTIVATED if called on a capture
handle that has been created but not activated, and PCAP_ERROR on other
errors. If PCAP_ERROR is returned, pcap_geterr(3PCAP) or
pcap_perror(3PCAP) may be called with p as an argument to fetch
or display the error text.