void
link_addr(
const char *addr
, struct sockaddr_dl *sdl
)
char
*
link_ntoa(
const struct sockaddr_dl *sdl
)
)
interprets character strings representing link-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.
Prior to a call to
link_addr(),
sdl->sdl_len
must be initialized to the size of the link-level socket structure,
typically
sizeof(struct
sockaddr_dl)
.
For
link_addr(),
the string
addr
may contain
an optional network interface identifier of the form
``name unit-number'',
suitable for the first argument to
ifconfig(8),
followed in all cases by a colon and
an interface 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.
)
always returns a null terminated string.
link_addr(
)
has no return value (See
BUGS).
)
and
link_ntoa(
)
functions appeared in
4.3BSDReno.
)
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.