| IF_NAMETOINDEX(3) | Library Functions Manual | IF_NAMETOINDEX(3) | 
if_nametoindex, if_indextoname,
  if_nameindex, if_freenameindex
  —
#include <net/if.h>
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);
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().
if_nametoindex() 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_nametoindex(),
  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.
| March 11, 2005 | NetBSD 10.0 |