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# getifaddrs

    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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