|GETIFADDRS(3)||FreeBSD Library Functions Manual||GETIFADDRS(3)|
NAMEgetifaddrs — get interface addresses
SYNOPSIS#include < ifaddrs.h>
getifaddrs( struct ifaddrs **ifap);
freeifaddrs( struct ifaddrs *ifp);
DESCRIPTIONThe 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 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 field contains a pointer to the next structure on the list. This field is NULL in last structure on the list.
ifa_name field contains the interface name.
ifa_flags field contains the interface flags, as set by ifconfig(8) utility.
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_netmask field references the netmask associated with
ifa_addr, if one is set, otherwise it is NULL.
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.
ifa_dstaddr field references the destination address on a P2P interface, if one exists, otherwise it is NULL.
ifa_data field 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 VALUESThe getifaddrs() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
ERRORSThe 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).
HISTORYThe getifaddrs implementation first appeared in BSDi BSD/OS.
BUGSIf both < net/if.h> and < ifaddrs.h> are being included, < net/if.h> must be included before < ifaddrs.h>.
|May 21, 2013||FreeBSD|