NAME
ether_ntoa,
ether_aton,
ether_ntohost,
ether_hostton,
ether_line, —
get ethers entry
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_ether.h>
char *
ether_ntoa(
const
struct ether_addr *e);
struct ether_addr *
ether_aton(
const
char *s);
int
ether_ntohost(
char
*hostname,
const struct
ether_addr *e);
int
ether_hostton(
const
char *hostname,
struct
ether_addr *e);
int
ether_line(
const
char *line,
struct
ether_addr *e,
char
*hostname);
DESCRIPTION
Ethernet addresses are represented by the following structure:
struct ether_addr {
u_char ether_addr_octet[6];
};
The
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
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.
The
ether_ntohost() and
ether_hostton()
functions interrogate the data base mapping host names to Ethernet addresses,
/etc/ethers. The
ether_ntohost() function
looks up the given Ethernet address and writes the associated host name into
the character buffer passed. The
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
/etc/ethers from the beginning; if a + appears alone on a
line in the file, then
ether_hostton() will consult the
ethers.byname YP map, and
ether_ntohost()
will consult the
ethers.byaddr YP map.
The
ether_line() function parses a line from the
/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.
The
hostname buffer for
ether_line() and
ether_ntohost() should be at least
MAXHOSTNAMELEN
+ 1 characters long, to prevent a
buffer overflow during parsing.
FILES
- /etc/ethers
-
SEE ALSO
ethers(5)
HISTORY
The
ether_ntoa(),
ether_aton(),
ether_ntohost(),
ether_hostton(), and
ether_line() functions were adopted from SunOS and appeared
in
NetBSD 1.0.
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.