rarp.c revision 1.29 
1/*	$NetBSD: rarp.c,v 1.29 2009/01/12 11:32:45 tsutsui 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 <net/if_ether.h>
45#include <netinet/in.h>
46
47#include <netinet/in_systm.h>
48
49#ifdef _STANDALONE
50#include <lib/libkern/libkern.h>
51#else
52#include <string.h>
53#endif
54
55#include "stand.h"
56#include "net.h"
57
58
59/*
60 * Ethernet Address Resolution Protocol.
61 *
62 * See RFC 826 for protocol description.  Structure below is adapted
63 * to resolving internet addresses.  Field names used correspond to
64 * RFC 826.
65 */
66struct ether_arp {
67	struct	 arphdr ea_hdr;			/* fixed-size header */
68	u_int8_t arp_sha[ETHER_ADDR_LEN];	/* sender hardware address */
69	u_int8_t arp_spa[4];			/* sender protocol address */
70	u_int8_t arp_tha[ETHER_ADDR_LEN];	/* target hardware address */
71	u_int8_t arp_tpa[4];			/* target protocol address */
72};
73#define	arp_hrd	ea_hdr.ar_hrd
74#define	arp_pro	ea_hdr.ar_pro
75#define	arp_hln	ea_hdr.ar_hln
76#define	arp_pln	ea_hdr.ar_pln
77#define	arp_op	ea_hdr.ar_op
78
79static ssize_t rarpsend __P((struct iodesc *, void *, size_t));
80static ssize_t rarprecv __P((struct iodesc *, void *, size_t, saseconds_t));
81
82/*
83 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826).
84 */
85int
86rarp_getipaddress(int sock)
87{
88	struct iodesc *d;
89	struct ether_arp *ap;
90	struct {
91		u_char header[ETHER_SIZE];
92		struct {
93			struct ether_arp arp;
94			u_char pad[18]; 	/* 60 - sizeof(arp) */
95		} data;
96	} wbuf;
97	struct {
98		u_char header[ETHER_SIZE];
99		struct {
100			struct ether_arp arp;
101			u_char pad[24]; 	/* extra space */
102		} data;
103	} rbuf;
104
105#ifdef RARP_DEBUG
106 	if (debug)
107		printf("rarp: socket=%d\n", sock);
108#endif
109	if (!(d = socktodesc(sock))) {
110		printf("rarp: bad socket. %d\n", sock);
111		return -1;
112	}
113#ifdef RARP_DEBUG
114 	if (debug)
115		printf("rarp: d=%lx\n", (u_long)d);
116#endif
117
118	(void)memset(&wbuf.data, 0, sizeof(wbuf.data));
119	ap = &wbuf.data.arp;
120	ap->arp_hrd = htons(ARPHRD_ETHER);
121	ap->arp_pro = htons(ETHERTYPE_IP);
122	ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */
123	ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */
124	ap->arp_op = htons(ARPOP_REVREQUEST);
125	(void)memcpy(ap->arp_sha, d->myea, 6);
126	(void)memcpy(ap->arp_tha, d->myea, 6);
127
128	if (sendrecv(d,
129	    rarpsend, &wbuf.data, sizeof(wbuf.data),
130	    rarprecv, &rbuf.data, sizeof(rbuf.data)) < 0)
131	{
132		printf("No response for RARP request\n");
133		return -1;
134	}
135
136	ap = &rbuf.data.arp;
137	(void)memcpy(&myip, ap->arp_tpa, sizeof(myip));
138#if 0
139	/* XXX - Can NOT assume this is our root server! */
140	(void)memcpy(&rootip, ap->arp_spa, sizeof(rootip));
141#endif
142
143	/* Compute our "natural" netmask. */
144	if (IN_CLASSA(myip.s_addr))
145		netmask = IN_CLASSA_NET;
146	else if (IN_CLASSB(myip.s_addr))
147		netmask = IN_CLASSB_NET;
148	else
149		netmask = IN_CLASSC_NET;
150
151	d->myip = myip;
152	return 0;
153}
154
155/*
156 * Broadcast a RARP request (i.e. who knows who I am)
157 */
158static ssize_t
159rarpsend(struct iodesc *d, void *pkt, size_t len)
160{
161
162#ifdef RARP_DEBUG
163 	if (debug)
164		printf("rarpsend: called\n");
165#endif
166
167	return sendether(d, pkt, len, bcea, ETHERTYPE_REVARP);
168}
169
170/*
171 * Returns 0 if this is the packet we're waiting for
172 * else -1 (and errno == 0)
173 */
174static ssize_t
175rarprecv(struct iodesc *d, void *pkt, size_t len, saseconds_t tleft)
176{
177	ssize_t n;
178	struct ether_arp *ap;
179	u_int16_t etype;	/* host order */
180
181#ifdef RARP_DEBUG
182 	if (debug)
183		printf("rarprecv: ");
184#endif
185
186	n = readether(d, pkt, len, tleft, &etype);
187	errno = 0;	/* XXX */
188	if (n == -1 || (size_t)n < sizeof(struct ether_arp)) {
189#ifdef RARP_DEBUG
190		if (debug)
191			printf("bad len=%d\n", (int)n);
192#endif
193		return -1;
194	}
195
196	if (etype != ETHERTYPE_REVARP) {
197#ifdef RARP_DEBUG
198		if (debug)
199			printf("bad type=0x%x\n", etype);
200#endif
201		return -1;
202	}
203
204	ap = (struct ether_arp *)pkt;
205	if (ap->arp_hrd != htons(ARPHRD_ETHER) ||
206	    ap->arp_pro != htons(ETHERTYPE_IP) ||
207	    ap->arp_hln != sizeof(ap->arp_sha) ||
208	    ap->arp_pln != sizeof(ap->arp_spa) )
209	{
210#ifdef RARP_DEBUG
211		if (debug)
212			printf("bad hrd/pro/hln/pln\n");
213#endif
214		return -1;
215	}
216
217	if (ap->arp_op != htons(ARPOP_REVREPLY)) {
218#ifdef RARP_DEBUG
219		if (debug)
220			printf("bad op=0x%x\n", ntohs(ap->arp_op));
221#endif
222		return -1;
223	}
224
225	/* Is the reply for our Ethernet address? */
226	if (memcmp(ap->arp_tha, d->myea, 6)) {
227#ifdef RARP_DEBUG
228		if (debug)
229			printf("unwanted address\n");
230#endif
231		return -1;
232	}
233
234	/* We have our answer. */
235#ifdef RARP_DEBUG
236 	if (debug)
237		printf("got it\n");
238#endif
239	return n;
240}
241