xref: /src/sys/lib/libsa/rarp.c

/*	$NetBSD: rarp.c,v 1.34 2019/04/05 20:09:29 christos Exp $	*/

/*
 * Copyright (c) 1992 Regents of the University of California.
 * All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Lawrence Berkeley Laboratory and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * @(#) Header: arp.c,v 1.5 93/07/15 05:52:26 leres Exp  (LBL)
 */
#include <sys/param.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_ether.h>
#include <netinet/in.h>

#include <netinet/in_systm.h>

#ifdef _STANDALONE
#include <lib/libkern/libkern.h>
#else
#include <string.h>
#endif

#include "stand.h"
#include "net.h"


/*
 * Ethernet Address Resolution Protocol.
 *
 * See RFC 826 for protocol description.  Structure below is adapted
 * to resolving internet addresses.  Field names used correspond to
 * RFC 826.
 */
struct ether_arp {
	struct	 arphdr ea_hdr;			/* fixed-size header */
	u_int8_t arp_sha[ETHER_ADDR_LEN];	/* sender hardware address */
	u_int8_t arp_spa[4];			/* sender protocol address */
	u_int8_t arp_tha[ETHER_ADDR_LEN];	/* target hardware address */
	u_int8_t arp_tpa[4];			/* target protocol address */
};
#define	arp_hrd	ea_hdr.ar_hrd
#define	arp_pro	ea_hdr.ar_pro
#define	arp_hln	ea_hdr.ar_hln
#define	arp_pln	ea_hdr.ar_pln
#define	arp_op	ea_hdr.ar_op

static ssize_t rarpsend(struct iodesc *, void *, size_t);
static ssize_t rarprecv(struct iodesc *, void *, size_t, saseconds_t);

/*
 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826).
 */
int
rarp_getipaddress(int sock)
{
	struct iodesc *d;
	struct ether_arp *ap;
	struct {
		u_char header[ETHERNET_HEADER_SIZE];
		struct {
			struct ether_arp arp;
			u_char pad[18]; 	/* 60 - sizeof(arp) */
		} data;
	} wbuf;
	struct {
		u_char header[ETHERNET_HEADER_SIZE];
		struct {
			struct ether_arp arp;
			u_char pad[24]; 	/* extra space */
		} data;
	} rbuf;

#ifdef RARP_DEBUG
 	if (debug)
		printf("%s: socket=%d\n", __func__, sock);
#endif
	if (!(d = socktodesc(sock))) {
		printf("%s: bad socket. %d\n", __func__, sock);
		return -1;
	}
#ifdef RARP_DEBUG
 	if (debug)
		printf("%s: d=%p\n", __func__, d);
#endif

	(void)memset(&wbuf.data, 0, sizeof(wbuf.data));
	ap = &wbuf.data.arp;
	ap->arp_hrd = htons(ARPHRD_ETHER);
	ap->arp_pro = htons(ETHERTYPE_IP);
	ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */
	ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */
	ap->arp_op = htons(ARPOP_REVREQUEST);
	(void)memcpy(ap->arp_sha, d->myea, ETHER_ADDR_LEN);
	(void)memcpy(ap->arp_tha, d->myea, ETHER_ADDR_LEN);

	if (sendrecv(d,
	    rarpsend, &wbuf.data, sizeof(wbuf.data),
	    rarprecv, &rbuf.data, sizeof(rbuf.data)) < 0)
	{
		printf("No response for RARP request\n");
		return -1;
	}

	ap = &rbuf.data.arp;
	(void)memcpy(&myip, ap->arp_tpa, sizeof(myip));
#if 0
	/* XXX - Can NOT assume this is our root server! */
	(void)memcpy(&rootip, ap->arp_spa, sizeof(rootip));
#endif

	/* Compute our "natural" netmask. */
	if (IN_CLASSA(myip.s_addr))
		netmask = IN_CLASSA_NET;
	else if (IN_CLASSB(myip.s_addr))
		netmask = IN_CLASSB_NET;
	else
		netmask = IN_CLASSC_NET;

	d->myip = myip;
	return 0;
}

/*
 * Broadcast a RARP request (i.e. who knows who I am)
 */
static ssize_t
rarpsend(struct iodesc *d, void *pkt, size_t len)
{

#ifdef RARP_DEBUG
 	if (debug)
		printf("%s: called\n", __func__);
#endif

	return sendether(d, pkt, len, bcea, ETHERTYPE_REVARP);
}

/*
 * Returns 0 if this is the packet we're waiting for
 * else -1 (and errno == 0)
 */
static ssize_t
rarprecv(struct iodesc *d, void *pkt, size_t len, saseconds_t tleft)
{
	ssize_t n;
	struct ether_arp *ap;
	u_int16_t etype;	/* host order */

#ifdef RARP_DEBUG
 	if (debug)
		printf("%s: ", __func__);
#endif

	n = readether(d, pkt, len, tleft, &etype);
	errno = 0;	/* XXX */
	if (n == -1 || (size_t)n < sizeof(struct ether_arp)) {
#ifdef RARP_DEBUG
		if (debug)
			printf("bad len=%d\n", (int)n);
#endif
		return -1;
	}

	if (etype != ETHERTYPE_REVARP) {
#ifdef RARP_DEBUG
		if (debug)
			printf("bad type=0x%x\n", etype);
#endif
		return -1;
	}

	ap = (struct ether_arp *)pkt;
	if (ap->arp_hrd != htons(ARPHRD_ETHER) ||
	    ap->arp_pro != htons(ETHERTYPE_IP) ||
	    ap->arp_hln != sizeof(ap->arp_sha) ||
	    ap->arp_pln != sizeof(ap->arp_spa) )
	{
#ifdef RARP_DEBUG
		if (debug)
			printf("bad hrd/pro/hln/pln\n");
#endif
		return -1;
	}

	if (ap->arp_op != htons(ARPOP_REVREPLY)) {
#ifdef RARP_DEBUG
		if (debug)
			printf("bad op=0x%x\n", ntohs(ap->arp_op));
#endif
		return -1;
	}

	/* Is the reply for our Ethernet address? */
	if (memcmp(ap->arp_tha, d->myea, ETHER_ADDR_LEN)) {
#ifdef RARP_DEBUG
		if (debug)
			printf("unwanted address\n");
#endif
		return -1;
	}

	/* We have our answer. */
#ifdef RARP_DEBUG
 	if (debug)
		printf("got it\n");
#endif
	return n;
}