1*479ab7f0SSascha Wildner /* $NetBSD: arp.c,v 1.18 1997/07/07 15:52:49 drochner Exp $ */
2*479ab7f0SSascha Wildner
3*479ab7f0SSascha Wildner /*
4*479ab7f0SSascha Wildner * Copyright (c) 1992 Regents of the University of California.
5*479ab7f0SSascha Wildner * All rights reserved.
6*479ab7f0SSascha Wildner *
7*479ab7f0SSascha Wildner * This software was developed by the Computer Systems Engineering group
8*479ab7f0SSascha Wildner * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9*479ab7f0SSascha Wildner * contributed to Berkeley.
10*479ab7f0SSascha Wildner *
11*479ab7f0SSascha Wildner * Redistribution and use in source and binary forms, with or without
12*479ab7f0SSascha Wildner * modification, are permitted provided that the following conditions
13*479ab7f0SSascha Wildner * are met:
14*479ab7f0SSascha Wildner * 1. Redistributions of source code must retain the above copyright
15*479ab7f0SSascha Wildner * notice, this list of conditions and the following disclaimer.
16*479ab7f0SSascha Wildner * 2. Redistributions in binary form must reproduce the above copyright
17*479ab7f0SSascha Wildner * notice, this list of conditions and the following disclaimer in the
18*479ab7f0SSascha Wildner * documentation and/or other materials provided with the distribution.
19*479ab7f0SSascha Wildner * 3. Neither the name of the University nor the names of its contributors
20*479ab7f0SSascha Wildner * may be used to endorse or promote products derived from this software
21*479ab7f0SSascha Wildner * without specific prior written permission.
22*479ab7f0SSascha Wildner *
23*479ab7f0SSascha Wildner * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24*479ab7f0SSascha Wildner * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25*479ab7f0SSascha Wildner * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26*479ab7f0SSascha Wildner * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27*479ab7f0SSascha Wildner * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28*479ab7f0SSascha Wildner * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29*479ab7f0SSascha Wildner * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30*479ab7f0SSascha Wildner * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31*479ab7f0SSascha Wildner * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32*479ab7f0SSascha Wildner * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33*479ab7f0SSascha Wildner * SUCH DAMAGE.
34*479ab7f0SSascha Wildner *
35*479ab7f0SSascha Wildner * @(#) Header: arp.c,v 1.5 93/07/15 05:52:26 leres Exp (LBL)
36*479ab7f0SSascha Wildner * $DragonFly: src/lib/libstand/arp.c,v 1.4 2005/12/11 02:27:26 swildner Exp $
37*479ab7f0SSascha Wildner */
38*479ab7f0SSascha Wildner
39*479ab7f0SSascha Wildner #include <sys/param.h>
40*479ab7f0SSascha Wildner #include <sys/socket.h>
41*479ab7f0SSascha Wildner #include <net/if.h>
42*479ab7f0SSascha Wildner #include <netinet/in.h>
43*479ab7f0SSascha Wildner #include <netinet/if_ether.h>
44*479ab7f0SSascha Wildner
45*479ab7f0SSascha Wildner #include <netinet/in_systm.h>
46*479ab7f0SSascha Wildner
47*479ab7f0SSascha Wildner #include <string.h>
48*479ab7f0SSascha Wildner
49*479ab7f0SSascha Wildner #include "stand.h"
50*479ab7f0SSascha Wildner #include "net.h"
51*479ab7f0SSascha Wildner
52*479ab7f0SSascha Wildner /* Cache stuff */
53*479ab7f0SSascha Wildner #define ARP_NUM 8 /* need at most 3 arp entries */
54*479ab7f0SSascha Wildner
55*479ab7f0SSascha Wildner struct arp_list {
56*479ab7f0SSascha Wildner struct in_addr addr;
57*479ab7f0SSascha Wildner u_char ea[6];
58*479ab7f0SSascha Wildner } arp_list[ARP_NUM] = {
59*479ab7f0SSascha Wildner /* XXX - net order `INADDR_BROADCAST' must be a constant */
60*479ab7f0SSascha Wildner { {0xffffffff}, BA }
61*479ab7f0SSascha Wildner };
62*479ab7f0SSascha Wildner int arp_num = 1;
63*479ab7f0SSascha Wildner
64*479ab7f0SSascha Wildner /* Local forwards */
65*479ab7f0SSascha Wildner static ssize_t arpsend(struct iodesc *, void *, size_t);
66*479ab7f0SSascha Wildner static ssize_t arprecv(struct iodesc *, void *, size_t, time_t);
67*479ab7f0SSascha Wildner
68*479ab7f0SSascha Wildner /* Broadcast an ARP packet, asking who has addr on interface d */
69*479ab7f0SSascha Wildner u_char *
arpwhohas(struct iodesc * d,struct in_addr addr)70*479ab7f0SSascha Wildner arpwhohas(struct iodesc *d, struct in_addr addr)
71*479ab7f0SSascha Wildner {
72*479ab7f0SSascha Wildner int i;
73*479ab7f0SSascha Wildner struct ether_arp *ah;
74*479ab7f0SSascha Wildner struct arp_list *al;
75*479ab7f0SSascha Wildner struct {
76*479ab7f0SSascha Wildner struct ether_header eh;
77*479ab7f0SSascha Wildner struct {
78*479ab7f0SSascha Wildner struct ether_arp arp;
79*479ab7f0SSascha Wildner u_char pad[18]; /* 60 - sizeof(...) */
80*479ab7f0SSascha Wildner } data;
81*479ab7f0SSascha Wildner } wbuf;
82*479ab7f0SSascha Wildner struct {
83*479ab7f0SSascha Wildner struct ether_header eh;
84*479ab7f0SSascha Wildner struct {
85*479ab7f0SSascha Wildner struct ether_arp arp;
86*479ab7f0SSascha Wildner u_char pad[24]; /* extra space */
87*479ab7f0SSascha Wildner } data;
88*479ab7f0SSascha Wildner } rbuf;
89*479ab7f0SSascha Wildner
90*479ab7f0SSascha Wildner /* Try for cached answer first */
91*479ab7f0SSascha Wildner for (i = 0, al = arp_list; i < arp_num; ++i, ++al)
92*479ab7f0SSascha Wildner if (addr.s_addr == al->addr.s_addr)
93*479ab7f0SSascha Wildner return (al->ea);
94*479ab7f0SSascha Wildner
95*479ab7f0SSascha Wildner /* Don't overflow cache */
96*479ab7f0SSascha Wildner if (arp_num > ARP_NUM - 1) {
97*479ab7f0SSascha Wildner arp_num = 1; /* recycle */
98*479ab7f0SSascha Wildner printf("arpwhohas: overflowed arp_list!\n");
99*479ab7f0SSascha Wildner }
100*479ab7f0SSascha Wildner
101*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
102*479ab7f0SSascha Wildner if (debug)
103*479ab7f0SSascha Wildner printf("arpwhohas: send request for %s\n", inet_ntoa(addr));
104*479ab7f0SSascha Wildner #endif
105*479ab7f0SSascha Wildner
106*479ab7f0SSascha Wildner bzero((char*)&wbuf.data, sizeof(wbuf.data));
107*479ab7f0SSascha Wildner ah = &wbuf.data.arp;
108*479ab7f0SSascha Wildner ah->arp_hrd = htons(ARPHRD_ETHER);
109*479ab7f0SSascha Wildner ah->arp_pro = htons(ETHERTYPE_IP);
110*479ab7f0SSascha Wildner ah->arp_hln = sizeof(ah->arp_sha); /* hardware address length */
111*479ab7f0SSascha Wildner ah->arp_pln = sizeof(ah->arp_spa); /* protocol address length */
112*479ab7f0SSascha Wildner ah->arp_op = htons(ARPOP_REQUEST);
113*479ab7f0SSascha Wildner MACPY(d->myea, ah->arp_sha);
114*479ab7f0SSascha Wildner bcopy(&d->myip, ah->arp_spa, sizeof(ah->arp_spa));
115*479ab7f0SSascha Wildner /* Leave zeros in arp_tha */
116*479ab7f0SSascha Wildner bcopy(&addr, ah->arp_tpa, sizeof(ah->arp_tpa));
117*479ab7f0SSascha Wildner
118*479ab7f0SSascha Wildner /* Store ip address in cache (incomplete entry). */
119*479ab7f0SSascha Wildner al->addr = addr;
120*479ab7f0SSascha Wildner
121*479ab7f0SSascha Wildner i = sendrecv(d,
122*479ab7f0SSascha Wildner arpsend, &wbuf.data, sizeof(wbuf.data),
123*479ab7f0SSascha Wildner arprecv, &rbuf.data, sizeof(rbuf.data));
124*479ab7f0SSascha Wildner if (i == -1) {
125*479ab7f0SSascha Wildner panic("arp: no response for %s\n",
126*479ab7f0SSascha Wildner inet_ntoa(addr));
127*479ab7f0SSascha Wildner }
128*479ab7f0SSascha Wildner
129*479ab7f0SSascha Wildner /* Store ethernet address in cache */
130*479ab7f0SSascha Wildner ah = &rbuf.data.arp;
131*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
132*479ab7f0SSascha Wildner if (debug) {
133*479ab7f0SSascha Wildner printf("arp: response from %s\n",
134*479ab7f0SSascha Wildner ether_sprintf(rbuf.eh.ether_shost));
135*479ab7f0SSascha Wildner printf("arp: cacheing %s --> %s\n",
136*479ab7f0SSascha Wildner inet_ntoa(addr), ether_sprintf(ah->arp_sha));
137*479ab7f0SSascha Wildner }
138*479ab7f0SSascha Wildner #endif
139*479ab7f0SSascha Wildner MACPY(ah->arp_sha, al->ea);
140*479ab7f0SSascha Wildner ++arp_num;
141*479ab7f0SSascha Wildner
142*479ab7f0SSascha Wildner return (al->ea);
143*479ab7f0SSascha Wildner }
144*479ab7f0SSascha Wildner
145*479ab7f0SSascha Wildner static ssize_t
arpsend(struct iodesc * d,void * pkt,size_t len)146*479ab7f0SSascha Wildner arpsend(struct iodesc *d, void *pkt, size_t len)
147*479ab7f0SSascha Wildner {
148*479ab7f0SSascha Wildner
149*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
150*479ab7f0SSascha Wildner if (debug)
151*479ab7f0SSascha Wildner printf("arpsend: called\n");
152*479ab7f0SSascha Wildner #endif
153*479ab7f0SSascha Wildner
154*479ab7f0SSascha Wildner return (sendether(d, pkt, len, bcea, ETHERTYPE_ARP));
155*479ab7f0SSascha Wildner }
156*479ab7f0SSascha Wildner
157*479ab7f0SSascha Wildner /*
158*479ab7f0SSascha Wildner * Returns 0 if this is the packet we're waiting for
159*479ab7f0SSascha Wildner * else -1 (and errno == 0)
160*479ab7f0SSascha Wildner */
161*479ab7f0SSascha Wildner static ssize_t
arprecv(struct iodesc * d,void * pkt,size_t len,time_t tleft)162*479ab7f0SSascha Wildner arprecv(struct iodesc *d, void *pkt, size_t len, time_t tleft)
163*479ab7f0SSascha Wildner {
164*479ab7f0SSascha Wildner ssize_t n;
165*479ab7f0SSascha Wildner struct ether_arp *ah;
166*479ab7f0SSascha Wildner u_int16_t etype; /* host order */
167*479ab7f0SSascha Wildner
168*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
169*479ab7f0SSascha Wildner if (debug)
170*479ab7f0SSascha Wildner printf("arprecv: ");
171*479ab7f0SSascha Wildner #endif
172*479ab7f0SSascha Wildner
173*479ab7f0SSascha Wildner n = readether(d, pkt, len, tleft, &etype);
174*479ab7f0SSascha Wildner errno = 0; /* XXX */
175*479ab7f0SSascha Wildner if (n == -1 || n < sizeof(struct ether_arp)) {
176*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
177*479ab7f0SSascha Wildner if (debug)
178*479ab7f0SSascha Wildner printf("bad len=%d\n", n);
179*479ab7f0SSascha Wildner #endif
180*479ab7f0SSascha Wildner return (-1);
181*479ab7f0SSascha Wildner }
182*479ab7f0SSascha Wildner
183*479ab7f0SSascha Wildner if (etype != ETHERTYPE_ARP) {
184*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
185*479ab7f0SSascha Wildner if (debug)
186*479ab7f0SSascha Wildner printf("not arp type=%d\n", etype);
187*479ab7f0SSascha Wildner #endif
188*479ab7f0SSascha Wildner return (-1);
189*479ab7f0SSascha Wildner }
190*479ab7f0SSascha Wildner
191*479ab7f0SSascha Wildner /* Ethernet address now checked in readether() */
192*479ab7f0SSascha Wildner
193*479ab7f0SSascha Wildner ah = (struct ether_arp *)pkt;
194*479ab7f0SSascha Wildner if (ah->arp_hrd != htons(ARPHRD_ETHER) ||
195*479ab7f0SSascha Wildner ah->arp_pro != htons(ETHERTYPE_IP) ||
196*479ab7f0SSascha Wildner ah->arp_hln != sizeof(ah->arp_sha) ||
197*479ab7f0SSascha Wildner ah->arp_pln != sizeof(ah->arp_spa) )
198*479ab7f0SSascha Wildner {
199*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
200*479ab7f0SSascha Wildner if (debug)
201*479ab7f0SSascha Wildner printf("bad hrd/pro/hln/pln\n");
202*479ab7f0SSascha Wildner #endif
203*479ab7f0SSascha Wildner return (-1);
204*479ab7f0SSascha Wildner }
205*479ab7f0SSascha Wildner
206*479ab7f0SSascha Wildner if (ah->arp_op == htons(ARPOP_REQUEST)) {
207*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
208*479ab7f0SSascha Wildner if (debug)
209*479ab7f0SSascha Wildner printf("is request\n");
210*479ab7f0SSascha Wildner #endif
211*479ab7f0SSascha Wildner arp_reply(d, ah);
212*479ab7f0SSascha Wildner return (-1);
213*479ab7f0SSascha Wildner }
214*479ab7f0SSascha Wildner
215*479ab7f0SSascha Wildner if (ah->arp_op != htons(ARPOP_REPLY)) {
216*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
217*479ab7f0SSascha Wildner if (debug)
218*479ab7f0SSascha Wildner printf("not ARP reply\n");
219*479ab7f0SSascha Wildner #endif
220*479ab7f0SSascha Wildner return (-1);
221*479ab7f0SSascha Wildner }
222*479ab7f0SSascha Wildner
223*479ab7f0SSascha Wildner /* Is the reply from the source we want? */
224*479ab7f0SSascha Wildner if (bcmp(&arp_list[arp_num].addr,
225*479ab7f0SSascha Wildner ah->arp_spa, sizeof(ah->arp_spa)))
226*479ab7f0SSascha Wildner {
227*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
228*479ab7f0SSascha Wildner if (debug)
229*479ab7f0SSascha Wildner printf("unwanted address\n");
230*479ab7f0SSascha Wildner #endif
231*479ab7f0SSascha Wildner return (-1);
232*479ab7f0SSascha Wildner }
233*479ab7f0SSascha Wildner /* We don't care who the reply was sent to. */
234*479ab7f0SSascha Wildner
235*479ab7f0SSascha Wildner /* We have our answer. */
236*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
237*479ab7f0SSascha Wildner if (debug)
238*479ab7f0SSascha Wildner printf("got it\n");
239*479ab7f0SSascha Wildner #endif
240*479ab7f0SSascha Wildner return (n);
241*479ab7f0SSascha Wildner }
242*479ab7f0SSascha Wildner
243*479ab7f0SSascha Wildner /*
244*479ab7f0SSascha Wildner * Convert an ARP request into a reply and send it.
245*479ab7f0SSascha Wildner * Notes: Re-uses buffer. Pad to length = 46.
246*479ab7f0SSascha Wildner *
247*479ab7f0SSascha Wildner * Parameters:
248*479ab7f0SSascha Wildner * pkt: the request
249*479ab7f0SSascha Wildner */
250*479ab7f0SSascha Wildner void
arp_reply(struct iodesc * d,void * pkt)251*479ab7f0SSascha Wildner arp_reply(struct iodesc *d, void *pkt)
252*479ab7f0SSascha Wildner {
253*479ab7f0SSascha Wildner struct ether_arp *arp = pkt;
254*479ab7f0SSascha Wildner
255*479ab7f0SSascha Wildner if (arp->arp_hrd != htons(ARPHRD_ETHER) ||
256*479ab7f0SSascha Wildner arp->arp_pro != htons(ETHERTYPE_IP) ||
257*479ab7f0SSascha Wildner arp->arp_hln != sizeof(arp->arp_sha) ||
258*479ab7f0SSascha Wildner arp->arp_pln != sizeof(arp->arp_spa) )
259*479ab7f0SSascha Wildner {
260*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
261*479ab7f0SSascha Wildner if (debug)
262*479ab7f0SSascha Wildner printf("arp_reply: bad hrd/pro/hln/pln\n");
263*479ab7f0SSascha Wildner #endif
264*479ab7f0SSascha Wildner return;
265*479ab7f0SSascha Wildner }
266*479ab7f0SSascha Wildner
267*479ab7f0SSascha Wildner if (arp->arp_op != htons(ARPOP_REQUEST)) {
268*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
269*479ab7f0SSascha Wildner if (debug)
270*479ab7f0SSascha Wildner printf("arp_reply: not request!\n");
271*479ab7f0SSascha Wildner #endif
272*479ab7f0SSascha Wildner return;
273*479ab7f0SSascha Wildner }
274*479ab7f0SSascha Wildner
275*479ab7f0SSascha Wildner /* If we are not the target, ignore the request. */
276*479ab7f0SSascha Wildner if (bcmp(arp->arp_tpa, &d->myip, sizeof(arp->arp_tpa)))
277*479ab7f0SSascha Wildner return;
278*479ab7f0SSascha Wildner
279*479ab7f0SSascha Wildner #ifdef ARP_DEBUG
280*479ab7f0SSascha Wildner if (debug) {
281*479ab7f0SSascha Wildner printf("arp_reply: to %s\n", ether_sprintf(arp->arp_sha));
282*479ab7f0SSascha Wildner }
283*479ab7f0SSascha Wildner #endif
284*479ab7f0SSascha Wildner
285*479ab7f0SSascha Wildner arp->arp_op = htons(ARPOP_REPLY);
286*479ab7f0SSascha Wildner /* source becomes target */
287*479ab7f0SSascha Wildner bcopy(arp->arp_sha, arp->arp_tha, sizeof(arp->arp_tha));
288*479ab7f0SSascha Wildner bcopy(arp->arp_spa, arp->arp_tpa, sizeof(arp->arp_tpa));
289*479ab7f0SSascha Wildner /* here becomes source */
290*479ab7f0SSascha Wildner bcopy(d->myea, arp->arp_sha, sizeof(arp->arp_sha));
291*479ab7f0SSascha Wildner bcopy(&d->myip, arp->arp_spa, sizeof(arp->arp_spa));
292*479ab7f0SSascha Wildner
293*479ab7f0SSascha Wildner /*
294*479ab7f0SSascha Wildner * No need to get fancy here. If the send fails, the
295*479ab7f0SSascha Wildner * requestor will just ask again.
296*479ab7f0SSascha Wildner */
297*479ab7f0SSascha Wildner (void) sendether(d, pkt, sizeof(*arp) + 18,
298*479ab7f0SSascha Wildner arp->arp_tha, ETHERTYPE_ARP);
299*479ab7f0SSascha Wildner }
300