GETIFADDRS(3) BSD Library Functions 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
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 */
ifa_next
Contains a pointer to the next structure on the list. This field
is set to NULL in 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 inter-
faces, 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 addresses
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).
BUGS
If both <net/if.h> and <ifaddrs.h> are being included, <net/if.h> must be
included before <ifaddrs.h>.
SEE ALSO
ioctl(2), socket(2), sysctl(3), networking(4), ifconfig(8)
HISTORY
The getifaddrs() function first appeared in BSDI BSD/OS. The function is
supplied on OpenBSD since OpenBSD 2.7.
BSD October 13, 2005 BSD
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