MirOS Manual: freeifaddrs(3), getifaddrs(3)

GETIFADDRS(3)              BSD Programmer's Manual               GETIFADDRS(3)


     getifaddrs - get interface addresses


     #include <sys/types.h>
     #include <sys/socket.h>
     #include <ifaddrs.h>

     getifaddrs(struct ifaddrs **ifap);

     freeifaddrs(struct ifaddrs *ifap);


     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 en-

         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 the 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
                    interfaces, 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 ad-
                    dresses 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.


     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 sysctl(3).


     ioctl(2), socket(2), sysctl(3), networking(4), ifconfig(8)


     The getifaddrs() function first appeared in BSDI BSD/OS. The function has
     been available 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>.

MirOS BSD #10-current          October 12, 1995                              1

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