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/*
* ethernet address conversion and lookup routines
*
* Written by Bill Paul <wpaul@ctr.columbia.edu>
* Center for Telecommunications Research
* Columbia University, New York City
*
* This code is public domain. There is no copyright. There are no
* distribution or usage restrictions. There are no strings attached.
*
* Have a party.
*
* $Id: ether_addr.c,v 1.4 1995/03/05 22:03:58 wpaul Exp $
*/
#include <stdio.h>
#include <sys/types.h>
#include <string.h>
#include <sys/param.h>
#ifndef _PATH_ETHERS
#define _PATH_ETHERS "/etc/ethers"
#endif
/*
* This should be defined in <netinet/if_ether.h> but it isn't.
*/
struct ether_addr {
unsigned char octet[6];
};
extern int yp_get_default_domain();
extern int yp_match();
char *yp_domain;
/*
* Parse a string of text containing an ethernet address and hostname
* and separate it into its component parts.
*/
int ether_line(l, e, hostname)
char *l;
struct ether_addr *e;
char *hostname;
{
int i, o[6];
i = sscanf(l, "%x:%x:%x:%x:%x:%x %s", &o[0], &o[1], &o[2],
&o[3], &o[4], &o[5],
hostname);
if (i != 7)
return (i);
for (i=0; i<6; i++)
e->octet[i] = o[i];
return (0);
}
/*
* Convert an ASCII representation of an ethernet address to
* binary form.
*/
struct ether_addr *ether_aton(a)
char *a;
{
int i;
static struct ether_addr o;
i = sscanf(a, "%x:%x:%x:%x:%x:%x", o.octet[0], o.octet[1], o.octet[2],
o.octet[3], o.octet[4], o.octet[5]);
if (i != 6)
return (NULL);
return ((struct ether_addr *)&o);
}
/*
* Convert a binary representation of an ethernet address to
* an ASCII string.
*/
char *ether_ntoa(n)
struct ether_addr *n;
{
int i;
static char a[18];
i = sprintf(a,"%x:%x:%x:%x:%x:%x",n->octet[0],n->octet[1],n->octet[2],
n->octet[3],n->octet[4],n->octet[5]);
if (i < 11)
return (NULL);
return ((char *)&a);
}
/*
* Map an ethernet address to a hostname. Use either /etc/ethers or
* NIS/YP.
*/
int ether_ntohost(hostname, e)
char *hostname;
struct ether_addr *e;
{
FILE *fp;
char buf[BUFSIZ];
struct ether_addr local_ether;
char local_host[MAXHOSTNAMELEN];
char *result;
int resultlen;
char *ether_a;
if ((fp = fopen(_PATH_ETHERS, "r")) == NULL)
return (1);
while (fgets(buf,BUFSIZ,fp)) {
if (buf[0] == '#')
continue;
if (buf[0] == '+') {
fclose(fp); /* Can ignore /etc/ethers from here on. */
if (yp_get_default_domain(&yp_domain))
return(1);
ether_a = ether_ntoa(e);
if (yp_match(yp_domain, "ethers.byaddr", ether_a,
strlen(ether_a), &result, &resultlen)) {
free(result);
return(1);
}
if (!ether_line(result, &local_ether, &local_host)) {
strcpy(hostname, (char *)&local_host);
free(result);
return(0);
} else {
free(result);
return(1);
}
}
if (!ether_line(&buf, &local_ether, &local_host)) {
if (!bcmp((char *)&local_ether.octet[0],
(char *)&e->octet[0], 6)) {
/* We have a match */
strcpy(hostname, (char *)&local_host);
fclose(fp);
return(0);
}
}
}
fclose(fp);
return (1);
}
/*
* Map a hostname to an ethernet address using /etc/ethers or
* NIS/YP.
*/
int ether_hostton(hostname, e)
char *hostname;
struct ether_addr *e;
{
FILE *fp;
char buf[BUFSIZ];
struct ether_addr local_ether;
char local_host[MAXHOSTNAMELEN];
char *result;
int resultlen;
if ((fp = fopen(_PATH_ETHERS, "r")) == NULL)
return (1);
while (fgets(buf,BUFSIZ,fp)) {
if (buf[0] == '#')
continue;
if (buf[0] == '+') {
fclose(fp); /* Can ignore /etc/ethers from here on. */
if (yp_get_default_domain(&yp_domain))
return(1);
if (yp_match(yp_domain, "ethers.byname", hostname,
strlen(hostname), &result, &resultlen)) {
free(result);
return(1);
}
if (!ether_line(result, &local_ether, &local_host)) {
bcopy((char *)&local_ether.octet[0],
(char *)&e->octet[0], 6);
free(result);
return(0);
} else {
free(result);
return(1);
}
}
if (!ether_line(&buf, &local_ether, &local_host)) {
if (!strcmp(hostname, (char *)&local_host)) {
/* We have a match */
bcopy((char *)&local_ether.octet[0],
(char *)&e->octet[0], 6);
fclose(fp);
return(0);
}
}
}
fclose(fp);
return (1);
}
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