LINK_ADDR(3)              OpenBSD Programmer's Manual             LINK_ADDR(3)

NAME
     link_addr, link_ntoa - elementary address specification routines for link
     level access



SYNOPSIS
     #include <sys/types.h>
     #include <sys/socket.h>
     #include <net/if_dl.h>

     void
     link_addr(const char *addr, struct sockaddr_dl *sdl);

     char *
     link_ntoa(const struct sockaddr_dl *sdl);

DESCRIPTION
     The link_addr() function interprets character strings representing link-
     level addresses, returning binary information suitable for use in system
     calls.  link_ntoa() takes a link-level address and returns an ASCII
     string representing some of the information present, including the link
     level address itself, and the interface name or number, if present.  This
     facility is experimental and is still subject to change.

     For link_addr(), the string addr may contain an optional network inter-
     face identifier of the form ``name unit-number'', suitable for the first
     argument to ifconfig(8),  followed in all cases by a colon and an inter-
     face address in the form of groups of hexadecimal digits separated by pe-
     riods.  Each group represents a byte of address; address bytes are filled
     left to right from low order bytes through high order bytes.

     Thus le0:8.0.9.13.d.30 represents an Ethernet address to be transmitted
     on the first Lance Ethernet interface.

RETURN VALUES
     link_ntoa() always returns a null-terminated string.  link_addr() has no
     return value.  (See BUGS.)

SEE ALSO
     iso(4),  ifconfig(8)

HISTORY
     The link_addr() and link_ntoa() functions appeared in 4.3BSD-Reno.

BUGS
     The returned values for link_ntoa reside in a static memory area.

     The function link_addr() should diagnose improperly formed input, and
     there should be an unambiguous way to recognize this.

     If the sdl_len field of the link socket address sdl is 0, link_ntoa()
     will not insert a colon before the interface address bytes.  If this
     translated address is given to link_addr() without inserting an initial
     colon, the latter will not interpret it correctly.

OpenBSD 2.6                      July 28, 1993                               1