Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
GETIFADDRS(3)		    Library Functions Manual		 GETIFADDRS(3)

NAME
       getifaddrs -- get interface addresses

SYNOPSIS
       #include	<ifaddrs.h>

       int
       getifaddrs(struct ifaddrs **ifap);

       void
       freeifaddrs(struct ifaddrs *ifp);

DESCRIPTION
       The  getifaddrs()  function  stores a reference to a linked list	of the
       network interfaces on the local machine in  the	memory	referenced  by
       ifap.   The  list consists of ifaddrs structures, as defined in the in-
       clude file <ifaddrs.h>.	The ifaddrs structure contains	at  least  the
       following entries:

	   struct ifaddrs   *ifa_next;	       /* Pointer to next struct */
	   char		    *ifa_name;	       /* Interface name */
	   u_int	     ifa_flags;	       /* Interface flags */
	   struct sockaddr  *ifa_addr;	       /* Interface address */
	   struct sockaddr  *ifa_netmask;      /* Interface netmask */
	   struct sockaddr  *ifa_broadaddr;    /* Interface broadcast address */
	   struct sockaddr  *ifa_dstaddr;      /* P2P interface	destination */
	   void		    *ifa_data;	       /* Address specific data	*/

       The  ifa_next  field  contains  a  pointer to the next structure	on the
       list.  This field is NULL in last structure on the list.

       The ifa_name field contains the interface name.

       The ifa_flags field contains the	interface flags, as set	by ifconfig(8)
       utility.

       The ifa_addr field references either the	address	of  the	 interface  or
       the link	level address of the interface,	if one exists, otherwise it is
       NULL.   (The  sa_family field of	the ifa_addr field should be consulted
       to determine the	format of the ifa_addr address.)

       The ifa_netmask field references	the netmask associated with  ifa_addr,
       if one is set, otherwise	it is NULL.

       The  ifa_broadaddr  field,  which should	only be	referenced for non-P2P
       interfaces, references the broadcast address associated with  ifa_addr,
       if one exists, otherwise	it is NULL.

       The  ifa_dstaddr	 field references the destination address on a P2P in-
       terface,	if one exists, otherwise it is NULL.

       The ifa_data field references address family specific data in a pointer
       to the struct if_data (as defined in  include  file  <net/if.h>).   For
       AF_LINK addresses, it contains various interface	attributes and statis-
       tics.   For  all	other address families,	it contains per-address	inter-
       face statistics.

       The data	returned by getifaddrs() is dynamically	allocated  and	should
       be freed	using freeifaddrs() when no longer needed.

RETURN VALUES
       The  getifaddrs() function returns the value 0 if successful; otherwise
       the value -1 is returned	and the	global variable	errno is set to	 indi-
       cate the	error.

ERRORS
       The getifaddrs()	may fail and set errno for any of the errors specified
       for the library routines	ioctl(2), socket(2), malloc(3) or sysctl(3).

SEE ALSO
       ioctl(2), socket(2), sysctl(3), networking(4), ifconfig(8)

HISTORY
       The getifaddrs implementation first appeared in BSDi BSD/OS.

BUGS
       If  both	<net/if.h> and <ifaddrs.h> are being included, <net/if.h> must
       be included before <ifaddrs.h>.

FreeBSD	13.2		       November	25, 2014		 GETIFADDRS(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY | BUGS

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=getifaddrs&manpath=FreeBSD+14.0-RELEASE+and+Ports>

home | help