LINK_ADDR(3) BSD Library Functions 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
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.
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.
BSD July 28, 1993 BSD
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