The
if_nametoindex() function maps the interface name specified in
ifname to its corresponding index. If the specified interface does not exist, it returns 0.
The
if_indextoname() function maps the interface index specified in
ifindex to it corresponding name, which is copied into the buffer pointed to by
ifname, which must be of at least IFNAMSIZ bytes. This pointer is also the return value of the function. If there is no interface corresponding to the specified index, NULL is returned.
The
if_nameindex() function returns an array of
if_nameindex structures, one structure per interface, as defined in the include file
<net/if.h>. The
if_nameindex structure contains at least the following entries:
unsigned int if_index; /* 1, 2, ... */
char *if_name; /* null terminated name: "le0", ... */
The end of the array of structures is indicated by a structure with an
if_index of 0 and an
if_name of NULL. A NULL pointer is returned upon an error.
The
if_freenameindex() function frees the dynamic memory that was allocated by
if_nameindex().