\" $NetBSD: ethers.3,v 1.15 2017/10/30 15:46:38 wiz Exp $
\"
\" Written by
[email protected]. Public domain.
\"
Dd November 2, 1997
Dt ETHERS 3
Os
Sh NAME
Nm ether_ntoa ,
Nm ether_aton ,
Nm ether_ntohost ,
Nm ether_hostton ,
Nm ether_line
Nd get ethers entry
Sh LIBRARY
Lb libc
Sh SYNOPSIS
In sys/types.h
In sys/socket.h
In net/if.h
In net/if_ether.h
Ft char *
Fn ether_ntoa "const struct ether_addr *e"
Ft struct ether_addr *
Fn ether_aton "const char *s"
Ft int
Fn ether_ntohost "char *hostname" "const struct ether_addr *e"
Ft int
Fn ether_hostton "const char *hostname" "struct ether_addr *e"
Ft int
Fn ether_line "const char *line" "struct ether_addr *e" "char *hostname"
Sh DESCRIPTION
Ethernet addresses are represented by the
following structure:
Bd -literal -offset indent
struct ether_addr {
u_char ether_addr_octet[6];
};
Ed
Pp
The
Fn ether_ntoa
function converts this structure into an ASCII string of the form
``xx:xx:xx:xx:xx:xx'', consisting of 6 hexadecimal numbers separated
by colons.
It returns a pointer to a static buffer that is reused for
each call.
The
Fn ether_aton
converts an ASCII string of the same form and to a structure
containing the 6 octets of the address.
It returns a pointer to a
static structure that is reused for each call.
Pp
The
Fn ether_ntohost
and
Fn ether_hostton
functions interrogate the data base mapping host names to Ethernet
addresses,
Pa /etc/ethers .
The
Fn ether_ntohost
function looks up the given Ethernet address and writes the associated
host name into the character buffer passed.
The
Fn ether_hostton
function looks up the given host name and writes the associated
Ethernet address into the structure passed.
Both functions return
zero if they find the requested host name or address, and -1 if not.
Each call reads
Pa /etc/ethers
from the beginning; if a + appears alone on a line in the file, then
Fn ether_hostton
will consult the
Pa ethers.byname
YP map, and
Fn ether_ntohost
will consult the
Pa ethers.byaddr
YP map.
Pp
The
Fn ether_line
function parses a line from the
Pa /etc/ethers
file and fills in the passed ``struct ether_addr'' and character
buffer with the Ethernet address and host name on the line.
It returns zero if the line was successfully parsed and -1 if not.
Pp
The
Fa hostname
buffer for
Fn ether_line
and
Fn ether_ntohost
should be at least
Dv MAXHOSTNAMELEN
+ 1
characters long, to prevent a buffer overflow during parsing.
Sh FILES
Bl -tag -width /etc/ethers -compact
It Pa /etc/ethers
El
Sh SEE ALSO
Xr ethers 5
Sh HISTORY
The
Fn ether_ntoa ,
Fn ether_aton ,
Fn ether_ntohost ,
Fn ether_hostton ,
and
Fn ether_line
functions were adopted from SunOS and appeared in
Nx 1.0 .
Sh BUGS
The data space used by these functions is static; if future use
requires the data, it should be copied before any subsequent calls to
these functions overwrite it.
