getifaddrs - get interface addresses
getifaddrs(struct ifaddrs **ifap);
freeifaddrs(struct ifaddrs *ifap);
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
<ifaddrs.h>. The ifaddrs structure contains at least the
struct ifaddrs *ifa_next; /* Pointer to next
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
void *ifa_data; /* Address specific
Contains a pointer to the next structure on the
list. This field
is set to NULL in last structure on the list.
Contains the interface name.
Contains the interface flags, as set by ifconfig(8).
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
determine the format of the ifa_addr address.)
References the netmask associated with ifa_addr, if
one is set,
otherwise it is NULL.
This field, which should only be referenced for nonP2P interfaces,
references the broadcast address associated
if one exists, otherwise it is NULL.
References the destination address on a P2P interface, if one exists,
otherwise it is NULL.
References address family specific data. For
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
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.
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 routines ioctl(2), socket(2), malloc(3), or
ioctl(2), socket(2), sysctl(3), networking(4), ifconfig(8)
The getifaddrs() function first appeared in BSDI BSD/OS.
The function is
supplied on OpenBSD since OpenBSD 2.7.
If both <net/if.h> and <ifaddrs.h> are being included,
<net/if.h> must be
included before <ifaddrs.h>.
OpenBSD 3.6 October 12, 1995
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