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rarp.c revision 1.4 
      1 /*	$NetBSD: rarp.c,v 1.4 1994/10/26 05:44:59 cgd Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1992 Regents of the University of California.
      5  * All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 3. All advertising materials mentioning features or use of this software
     20  *    must display the following acknowledgement:
     21  *	This product includes software developed by the University of
     22  *	California, Lawrence Berkeley Laboratory and its contributors.
     23  * 4. Neither the name of the University nor the names of its contributors
     24  *    may be used to endorse or promote products derived from this software
     25  *    without specific prior written permission.
     26  *
     27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     37  * SUCH DAMAGE.
     38  *
     39  * @(#) Header: arp.c,v 1.5 93/07/15 05:52:26 leres Exp  (LBL)
     40  */
     41 #include <sys/param.h>
     42 #include <sys/socket.h>
     43 #include <net/if.h>
     44 #include <netinet/in.h>
     45 
     46 #include <netinet/if_ether.h>
     47 #include <netinet/in_systm.h>
     48 
     49 #include <string.h>
     50 
     51 #include "stand.h"
     52 #include "net.h"
     53 #include "netif.h"
     54 
     55 static int rarpsend(struct iodesc *, void *, int);
     56 static int rarprecv(struct iodesc *, void *, int);
     57 
     58 /*
     59  * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826).
     60  */
     61 n_long
     62 rarp_getipaddress(sock)
     63 	int sock;
     64 {
     65 	struct iodesc *d;
     66 	register struct ether_arp *ap;
     67 	register void *pkt;
     68 	struct {
     69 		u_char header[HEADER_SIZE];
     70 		struct ether_arp wrarp;
     71 	} wbuf;
     72 	union {
     73 		u_char buffer[RECV_SIZE];
     74 		struct {
     75 			u_char header[HEADER_SIZE];
     76 			struct ether_arp xrrarp;
     77 		}xrbuf;
     78 #define rrarp  xrbuf.xrrarp
     79 	} rbuf;
     80 
     81 #ifdef RARP_DEBUG
     82  	if (debug)
     83 		printf("rarp: socket=%d\n", sock);
     84 #endif
     85 	if (!(d = socktodesc(sock))) {
     86 		printf("rarp: bad socket. %d\n", sock);
     87 		return(INADDR_ANY);
     88 	}
     89 #ifdef RARP_DEBUG
     90  	if (debug)
     91 		printf("rarp: d=%x\n", (u_int)d);
     92 #endif
     93 	ap = &wbuf.wrarp;
     94 	pkt = &rbuf.rrarp;
     95 	pkt -= HEADER_SIZE;
     96 
     97 	bzero(ap, sizeof(*ap));
     98 
     99 	ap->arp_hrd = htons(ARPHRD_ETHER);
    100 	ap->arp_pro = htons(ETHERTYPE_IP);
    101 	ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */
    102 	ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */
    103 	ap->arp_op = htons(ARPOP_REQUEST);
    104 	bcopy(d->myea, ap->arp_sha, 6);
    105 	bcopy(d->myea, ap->arp_tha, 6);
    106 
    107 	if (sendrecv(d,
    108 		     rarpsend, ap, sizeof(*ap),
    109 		     rarprecv, pkt, RECV_SIZE) < 0) {
    110 		printf("No response for RARP request\n");
    111 		return(INADDR_ANY);
    112 	}
    113 
    114 	return(myip);
    115 }
    116 
    117 /*
    118  * Broadcast a RARP request (i.e. who knows who I am)
    119  */
    120 static int
    121 rarpsend(d, pkt, len)
    122 	register struct iodesc *d;
    123 	register void *pkt;
    124 	register int len;
    125 {
    126 #ifdef RARP_DEBUG
    127  	if (debug)
    128  	    printf("rarpsend: called\n");
    129 #endif
    130 	return (sendether(d, pkt, len, bcea, ETHERTYPE_REVARP));
    131 }
    132 
    133 /*
    134  * Called when packet containing RARP is received
    135  */
    136 static int
    137 rarprecv(d, pkt, len)
    138 	register struct iodesc *d;
    139 	register void *pkt;
    140 	register int len;
    141 {
    142 	register struct ether_header *ep;
    143 	register struct ether_arp *ap;
    144 
    145 #ifdef RARP_DEBUG
    146  	if (debug)
    147  	    printf("rarprecv: called\n");
    148 #endif
    149 	if (len < sizeof(struct ether_header) + sizeof(struct ether_arp)) {
    150 		errno = 0;
    151 		return (-1);
    152 	}
    153 
    154 	ep = (struct ether_header *)pkt;
    155 	if (ntohs(ep->ether_type) != ETHERTYPE_REVARP) {
    156 		errno = 0;
    157 		return (-1);
    158 	}
    159 
    160 	ap = (struct ether_arp *)(ep + 1);
    161 	if (ntohs(ap->arp_op) != ARPOP_REPLY ||
    162 	    ntohs(ap->arp_pro) != ETHERTYPE_IP)  {
    163 		errno = 0;
    164 		return (-1);
    165 	}
    166 
    167 	if (bcmp(ap->arp_tha, d->myea, 6)) {
    168 		errno = 0;
    169 		return (-1);
    170 	}
    171 
    172 	bcopy(ap->arp_tpa, (char *)&myip, sizeof(myip));
    173 	bcopy(ap->arp_spa, (char *)&rootip, sizeof(rootip));
    174 
    175 	return(0);
    176 }
    177