unsigned
int
if_nametoindex(
const char *ifname
)
char
*
if_indextoname(
unsigned int ifindex
, char *ifname
)
struct
if_nameindex
*
if_nameindex(
void
)
void
if_freenameindex(
struct if_nameindex *ptr
)
)
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(
).
)
returns the index number of the interface.
If the interface is not found, a value of 0 is returned and
errno
is set to
ENXIO
.
A value of 0 is also returned if an error
occurs while retrieving the list of interfaces via
getifaddrs(3).
Upon successful completion,
if_indextoname()
returns
ifname.
If the interface is not found, a NULL pointer is returned and
errno
is set to
ENXIO
.
A NULL pointer is also returned if an error
occurs while retrieving the list of interfaces via
getifaddrs(3).
The
if_nameindex()
returns a NULL pointer if an error
occurs while retrieving the list of interfaces via
getifaddrs(3),
or if sufficient memory cannot be allocated.
),
if_indextoname(
),
if_nameindex(
),
and
if_freenameindex(
)
functions conform to
IEEE Std 1003.1-2001 (``POSIX.1'') ,
X/Open Networking Services Issue 5.2 (``XNS5.2'') ,
and RFC 3493.