GETIFADDRS(3SOCKET)GETIFADDRS(3SOCKET)NAME
getifaddrs, freeifaddrs - get interface addresses
SYNOPSIS
cc [ flag ... ] file ... -lsocket -lnsl [ library ... ]
#include <sys/types.h>
#include <sys/socket.h>
#include <ifaddrs.h>
int getifaddrs(struct ifaddrs **ifap);
void freeifaddrs(struct ifaddrs *ifp);
DESCRIPTION
The getifaddrs() function is used to obtain the list of network inter‐
faces on the local machine. A reference to a linked list of ifaddrs
structures, as defined in <ifaddrs.h>, is stored in the memory refer‐
enced by ifap. Each structure in the list describes one network inter‐
face address, and is of the form:
struct ifaddrs {
struct ifaddrs *ifa_next;
char *ifa_name;
uint64_t ifa_flags;
struct sockaddr *ifa_addr;
struct sockaddr *ifa_netmask;
union {
struct sockaddr *ifu_broadaddr;
struct sockaddr *ifu_dstaddr;
} ifa_ifu;
void *ifa_data;
};
#define ifa_broadaddr ifa_ifu.ifu_broadaddr
#define ifa_dstaddr ifa_ifu.ifu_dstaddr
The list is traversed by following the ifa_next pointer. This member
is NULL on the last structure in the list.
The ifa_name member contains the interface name.
The ifa_flags member contains the interface flags.
The ifa_addr member references the address of the interface. Use the
sa_family member of this structure to determine the format of the
address, as described in socket.h(3HEAD).
The ifa_netmask member references the netmask associated with ifa_addr,
or NULL if one is not set.
If the IFF_BROADCAST bit is set in ifa_flags, then ifa_broadaddr is
valid, or NULL if not present. If the IFF_POINTOPOINT bit is set, then
ifa_dstaddr is valid, or NULL if not present. These two flags are
mutually exclusive; see if_tcp(7P) for more information.
The ifa_data member is presently unused.
The memory used by getifaddrs() to back the list is dynamically allo‐
cated. It should be freed using freeifaddrs().
RETURN VALUES
If successful, getifaddrs() returns the value 0; otherwise it returns
−1 and sets errno to indicate the error.
ERRORS
The getifaddrs() function may fail and set errno for any of the errors
specified for the library routines ioctl(2), socket(3SOCKET), and mal‐
loc(3C).
ATTRIBUTES
┌────────────────────┬─────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼─────────────────┤
│Interface Stability │ Committed │
├────────────────────┼─────────────────┤
│MT-Level │ MT-Safe │
└────────────────────┴─────────────────┘
SEE ALSOipadm(1M), ifconfig(1M), ioctl(2), malloc(3C), socket(3SOCKET),
socket.h(3HEAD), if_tcp(7P), attributes(5)NOTES
On an illumos system, this function lists only interfaces with the
IFF_UP flag set; see if_tcp(7P) and ifconfig(1M) for more information.
BUGS
At present, this function only lists addresses from the AF_INET and
AF_INET6 families. Other families, such as AF_LINK, are not included.
Apr 18, 2013 GETIFADDRS(3SOCKET)
