/*      $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;
}

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