if_nametoindex(3SOCKET) 				     Sockets Library Functions					   if_nametoindex(3SOCKET)

NAME

       if_nametoindex,	if_indextoname,  if_nameindex,	if_freenameindex - routines to map Internet Protocol network interface names and interface
       indexes

SYNOPSIS

       cc [ flag... ] file... -lsocket [ library... ]
       #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);

PARAMETERS

       ifname	       interface name

       ifindex	       interface index

       ptr	       pointer returned by if_nameindex()

DESCRIPTION

       This API defines two functions that map between an Internet Protocol network interface name and index, a third function	that  returns  all
       the interface names and indexes, and a fourth function to return the dynamic memory allocated by the previous function.

       Network	interfaces  are  normally  known by names such as eri0, sl1, ppp2, and the like.  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.  IF_NAMESIZE  is  defined	in
       <net/if.h> and its value includes a terminating null byte at the end of the interface name.

       if_nametoindex()

	   The	if_nametoindex() function returns the interface index corresponding to the interface name pointed to by the ifname pointer. If the
	   specified interface name does not exist, the return value is 0, and errno is set to ENXIO. If there was a system error, such as running
	   out of memory, the return value is 0 and errno is set to the proper value, for example, ENOMEM.

       if_indextoname()

	   The	if_indextoname()  function maps an interface index into its corresponding name. This pointer is also the return value of the func-
	   tion.  If there is no interface corresponding to the specified index, NULL is returned, and errno is set to ENXIO, if there was a  sys-
	   tem	error,	such  as  running  out	of  memory, if_indextoname() returns NULL and errno would be set to the proper value, for example,
	   ENOMEM.

       *if_nameindex()

	   The if_nameindex() function returns an array of if_nameindex structures, one structure per interface. The if_nameindex structure  holds
	   the information about a single interface and is defined when the <net/if.h> header is included:

	   struct if_nameindex
	      unsigned int   if_index; /* 1, 2, ... */
	      char	    *if_name;  /* null terminated name: "eri0", ... */
	   };

	   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 sets errno to the appropriate value. The memory used for this array of structures along with the  inter-
	   face names pointed to by the if_name members is obtained dynamically. This memory is freed by the if_freenameindex() function.

       if_freenameindex()

	   The	if_freenameindex() function frees the dynamic memory that was allocated by if_nameindex(). The argument to this function must be a
	   pointer that was returned by if_nameindex().

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsl (32-bit)		   |
       +-----------------------------+-----------------------------+
       |			     |SUNWcslx (64-bit) 	   |
       +-----------------------------+-----------------------------+
       |MT Level		     |MT Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ifconfig(1M), if_nametoindex(3XNET), attributes(5), if(7P)

SunOS 5.10							    12 Dec 2003 					   if_nametoindex(3SOCKET)