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LINK_ADDR(3)             BSD Library Functions Manual             LINK_ADDR(3)

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

LIBRARY
     Standard C Library (libc, -lc)

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 routine link_addr() interprets character strings representing link-level linklevel
     level addresses, returning binary information suitable for use in system
     calls.  The routine 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 interface
     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 interface
     face address in the form of groups of hexadecimal digits separated by
     periods.  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.

     The direct use of these functions is deprecated in favor of the
     addr2ascii(3) interface; however, portable programs cannot rely on the
     latter as it is not yet widely implemented.

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

SEE ALSO
     addr2ascii(3)

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.

BSD                              June 17, 1996                             BSD