GETIFADDRS(3) BSD Programmer's Manual GETIFADDRS(3)NAME
getifaddrs - get interface addresses
SYNOPSIS
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
int
getifaddrs(struct ifaddrs **ifap);
void
freeifaddrs(struct ifaddrs *ifap);
DESCRIPTION
The getifaddrs() function stores a reference to a linked list of the net-
work interfaces on the local machine in the memory referenced by ifap.
The list consists of ifaddrs structures, as defined in the include file
<ifaddrs.h>. The ifaddrs structure contains at least the following en-
tries:
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 */
ifa_next Contains a pointer to the next structure on the list. This
field is set to NULL in the last structure on the list.
ifa_name Contains the interface name.
ifa_flags Contains the interface flags, as set by ifconfig(8).
ifa_addr 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.)
ifa_netmask References the netmask associated with ifa_addr, if one is
set, otherwise it is NULL.
ifa_broadaddr This 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.
ifa_dstaddr References the destination address on a P2P interface, if
one exists, otherwise it is NULL.
ifa_data References address family specific data. For AF_LINK ad-
dresses it contains a pointer to the struct if_data (as
defined in include file <net/if.h>) which contains various
interface attributes and statistics. For all other address
families, it contains a pointer to the struct ifa_data (as
defined in include file <net/if.h>) which contains per-
address interface statistics.
The data returned by getifaddrs() is dynamically allocated and should be
freed using freeifaddrs() when no longer needed.
RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value
of -1 is returned and errno is set to indicate 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 ALSOioctl(2), socket(2), sysctl(3), networking(4), ifconfig(8)HISTORY
The getifaddrs() function first appeared in BSDI BSD/OS. The function has
been available on OpenBSD since OpenBSD 2.7.
BUGS
If both <net/if.h> and <ifaddrs.h> are being included, <net/if.h> must be
included before <ifaddrs.h>.
MirOS BSD #10-current October 12, 1995 1
