rarp.c revision 1.5 
1/*	$NetBSD: rarp.c,v 1.5 1995/02/20 11:04:16 mycroft 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
55static size_t rarpsend __P((struct iodesc *, void *, size_t));
56static size_t rarprecv __P((struct iodesc *, void *, size_t, time_t));
57
58/*
59 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826).
60 */
61n_long
62rarp_getipaddress(sock)
63	int sock;
64{
65	struct iodesc *d;
66	register struct ether_arp *ap;
67	struct {
68		u_char header[HEADER_SIZE];
69		struct ether_arp wrarp;
70	} wbuf;
71	struct {
72		u_char header[HEADER_SIZE];
73		struct ether_arp rrarp;
74	} rbuf;
75
76#ifdef RARP_DEBUG
77 	if (debug)
78		printf("rarp: socket=%d\n", sock);
79#endif
80	if (!(d = socktodesc(sock))) {
81		printf("rarp: bad socket. %d\n", sock);
82		return(INADDR_ANY);
83	}
84#ifdef RARP_DEBUG
85 	if (debug)
86		printf("rarp: d=%x\n", (u_int)d);
87#endif
88
89	ap = &wbuf.wrarp;
90	bzero(ap, sizeof(*ap));
91
92	ap->arp_hrd = htons(ARPHRD_ETHER);
93	ap->arp_pro = htons(ETHERTYPE_IP);
94	ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */
95	ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */
96	ap->arp_op = htons(ARPOP_REQUEST);
97	bcopy(d->myea, ap->arp_sha, 6);
98	bcopy(d->myea, ap->arp_tha, 6);
99
100	if (sendrecv(d,
101	    rarpsend, ap, sizeof(*ap),
102	    rarprecv, &rbuf.rrarp, sizeof(rbuf.rrarp)) < 0) {
103		printf("No response for RARP request\n");
104		return(INADDR_ANY);
105	}
106
107	return (myip);
108}
109
110/*
111 * Broadcast a RARP request (i.e. who knows who I am)
112 */
113static size_t
114rarpsend(d, pkt, len)
115	register struct iodesc *d;
116	register void *pkt;
117	register size_t len;
118{
119
120#ifdef RARP_DEBUG
121 	if (debug)
122		printf("rarpsend: called\n");
123#endif
124
125	return (sendether(d, pkt, len, bcea, ETHERTYPE_REVARP));
126}
127
128/*
129 * Called when packet containing RARP is received
130 */
131static size_t
132rarprecv(d, pkt, len, tleft)
133	register struct iodesc *d;
134	register void *pkt;
135	register size_t len;
136	time_t tleft;
137{
138	register struct ether_header *eh;
139	register struct ether_arp *ap;
140
141#ifdef RARP_DEBUG
142 	if (debug)
143 		printf("rarprecv: called\n");
144#endif
145
146	len = readether(d, pkt, len, tleft);
147	if (len == -1 || len < sizeof(struct ether_arp))
148		goto bad;
149
150	eh = (struct ether_header *)pkt - 1;
151	if (ntohs(eh->ether_type) != ETHERTYPE_REVARP)
152		goto bad;
153
154	ap = (struct ether_arp *)pkt;
155	if (ntohs(ap->arp_op) != ARPOP_REPLY ||
156	    ntohs(ap->arp_pro) != ETHERTYPE_IP)
157		goto bad;
158
159	if (bcmp(ap->arp_tha, d->myea, 6))
160		goto bad;
161
162	bcopy(ap->arp_tpa, (char *)&myip, sizeof(myip));
163	bcopy(ap->arp_spa, (char *)&rootip, sizeof(rootip));
164
165	return (0);
166
167bad:
168	errno = 0;
169	return (-1);
170}
171