/* Origin NetBSD: src/lib/libc/net/ethers.c */

/*
 * ethers(3N) a la Sun.
 *
 * Written by Roland McGrath <roland@frob.com> 10/14/93.
 * Public domain.
 *
 * port for musl by Abdoulaye Walsimou GAYE <awg@embtoolkit.org> 2012/10/15
 */

#define _BSD_SOURCE
#include <net/ethernet.h>
#include <netinet/ether.h>

#include <sys/param.h>
#include <assert.h>
#include <errno.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifndef _PATH_ETHERS
#define _PATH_ETHERS "/etc/ethers"
#endif

/*
 * ether_ntoa():
 * This 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.
 */
char *ether_ntoa(const struct ether_addr *e)
{
	static char a[18];

	assert(e != NULL);

	(void) snprintf(a, sizeof a, "%02x:%02x:%02x:%02x:%02x:%02x",
	    e->ether_addr_octet[0], e->ether_addr_octet[1],
	    e->ether_addr_octet[2], e->ether_addr_octet[3],
	    e->ether_addr_octet[4], e->ether_addr_octet[5]);
	return a;
}

/*
 * ether_aton():
 * This function 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.
 */
struct ether_addr *ether_aton(const char *s)
{
	static struct ether_addr n;
	unsigned int i[6];

	assert(s != NULL);

	if (sscanf(s, " %x:%x:%x:%x:%x:%x ", &i[0], &i[1],
	    &i[2], &i[3], &i[4], &i[5]) == 6) {
		n.ether_addr_octet[0] = (unsigned char)i[0];
		n.ether_addr_octet[1] = (unsigned char)i[1];
		n.ether_addr_octet[2] = (unsigned char)i[2];
		n.ether_addr_octet[3] = (unsigned char)i[3];
		n.ether_addr_octet[4] = (unsigned char)i[4];
		n.ether_addr_octet[5] = (unsigned char)i[5];
		return &n;
	}
	return NULL;
}

/*
 * ether_ntohost():
 * This function interrogates the data base mapping host names to Ethernet
 * addresses, /etc/ethers.
 * It looks up the given Ethernet address and writes the associated host name
 * into the character buffer passed.
 * It returns zero if it finds the requested host name and -1 if not.
 */
int ether_ntohost(char *hostname, const struct ether_addr *e)
{
	FILE *f;
	char *p;
	size_t len;
	struct ether_addr try;

	assert(hostname != NULL);
	assert(e != NULL);

	f = fopen(_PATH_ETHERS, "r");
	if (f == NULL)
		return -1;
	while ((p = fgetln(f, &len)) != NULL) {
		if (p[len - 1] != '\n')
			continue;		/* skip lines w/o \n */
		p[--len] = '\0';
		if (ether_line(p, &try, hostname) == 0 &&
		    memcmp(&try, e, sizeof try) == 0) {
			(void)fclose(f);
			return 0;
		}
	}
	(void)fclose(f);
	errno = ENOENT;
	return -1;
}

/*
 * ether_hostton():
 * This function interrogates the data base mapping host names to Ethernet
 * addresses, /etc/ethers.
 * It looks up the given host name and writes the associated Ethernet address
 * into the structure passed.
 * It returns zero if it finds the requested address and -1 if not.
 */
int ether_hostton(const char *hostname, struct ether_addr *e)
{
	FILE *f;
	char *p;
	size_t len;
	char try[MAXHOSTNAMELEN + 1];

	assert(hostname != NULL);
	assert(e != NULL);

	f = fopen(_PATH_ETHERS, "r");
	if (f==NULL)
		return -1;

	while ((p = fgetln(f, &len)) != NULL) {
		if (p[len - 1] != '\n')
			continue;		/* skip lines w/o \n */
		p[--len] = '\0';
		if (ether_line(p, e, try) == 0 && strcmp(hostname, try) == 0) {
			(void)fclose(f);
			return 0;
		}
	}
	(void)fclose(f);
	errno = ENOENT;
	return -1;
}

/*
 * ether_line():
 * This 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.
 */
int ether_line(const char *l, struct ether_addr *e, char *hostname)
{
	unsigned int i[6];

#define S2(arg) #arg
#define S1(arg) S2(arg)
	static const char fmt[] = " %x:%x:%x:%x:%x:%x"
	    " %" S1(MAXHOSTNAMELEN) "s\n";
#undef S2
#undef S1

	assert(l != NULL);
	assert(e != NULL);
	assert(hostname != NULL);

	if (sscanf(l, fmt,
	    &i[0], &i[1], &i[2], &i[3], &i[4], &i[5], hostname) == 7) {
		e->ether_addr_octet[0] = (unsigned char)i[0];
		e->ether_addr_octet[1] = (unsigned char)i[1];
		e->ether_addr_octet[2] = (unsigned char)i[2];
		e->ether_addr_octet[3] = (unsigned char)i[3];
		e->ether_addr_octet[4] = (unsigned char)i[4];
		e->ether_addr_octet[5] = (unsigned char)i[5];
		return 0;
	}
	errno = EINVAL;
	return -1;
}