/*      $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;
}