HP-UX Reference (11i v2 07/12) - 3 Library Functions A-M (vol 6)

i
if_nameindex(3N) if_nameindex(3N)
NAME
if_nameindex(), if_nametoindex(), if_indextoname(), if_freenameindex() - functions that map between an
interface name and index
SYNOPSIS
#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);
DESCRIPTION
Interfaces are normally known by names such as "lan0", "vlan200" etc., and index is an unique positive
integer value assigned to an interface. Index values start at 1, and 0 is not a valid index.
if_nametoindex()
This function maps an interface name into its corresponding index. If the specified interface name
does not exist, the return value is set to 0 and errno is set to [ENXIO]. If there is a system error, the
return value is 0, and errno is set to the appropriate value. For example, if the system is running out
of memory, errno will be set to [ENOMEM].
if_indextoname()
This function maps an interface index into its corresponding name. The ifname argument must point
to a buffer of at least
IF_NAMESIZE bytes into which the interface name corresponding to the
specified index is returned. This pointer is also the return value of the function. IF_NAMESIZE
is
defined in
<net/if6.h> and its value includes a terminating null byte at the end of the interface
name. If there is no interface corresponding to the specified index, NULL is returned and errno is set
to [ENXIO]. If there is a system error, the return value is 0, and errno is set to the appropriate value.
if_nameindex()
This function returns all interface names and indexes as an array of if_nameindex structures, one
structure per interface. The if_nameindex structure is defined in <net/if6.h> .
struct if_nameindex {
unsigned int if_index; /* 1, 2, ... */
char *if_name; /* null terminated name: "lan0" */
};
The end of the array of structures is indicated by a structure with an if_index of 0, and an if_name of
NULL. The function returns a NULL pointer upon an error, and would set errno to the appropriate
value.
The memory used for this array of structures along with the interface names pointed to by the
if_name members is obtained dynamically. This memory is freed by the next
if_freenameindex()
function.
if_freenameindex()
This function frees the dynamic memory allocated by if_nameindex(). The argument to this
function must be a pointer that was returned by if_nameindex().
The function prototypes and struct if_nameindex are defined in <net/if6.h> . Applications are
not required to include this header file explicitly; it is automatically included by <net/if.h>.
Applications using these functions should link with -lipv6.
ERRORS
When if_nametoindex() or if_indextoname()
fails, the following error message is set in errno.
[ENXIO] The specified interface or index does not exist.
AUTHOR
These functions were developed by Hewlett-Packard.
636 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: December 2007 Update