GETIFADDRS(3) BSD Library Functions Manual GETIFADDRS(3)
getifaddrs -- get interface addresses
getifaddrs(struct ifaddrs **ifap);
freeifaddrs(struct ifaddrs *ifp);
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 struc-
tures, 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 */
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, other-
wise 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 interface, if one exists,
otherwise it is NULL.
The ifa_data field references address family specific data. For AF_LINK addresses it con-
tains 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 is NULL.
The data returned by getifaddrs() is dynamically allocated and should be freed using
freeifaddrs() when no longer needed.
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned
and errno is set to indicate the error.
The getifaddrs() may fail and set errno for any of the errors specified for the library rou-
tines ioctl(2), socket(2), malloc(3) or sysctl(3).
ioctl(2), socket(2), sysctl(3), networking(4), ifconfig(8)
The getifaddrs implementation first appeared in BSD/OS.
If both <net/if.h> and <ifaddrs.h> are being included, <net/if.h> must be included before
BSD April 21, 2009 BSD