1 /* $OpenBSD: rarp.c,v 1.10 2003/08/11 06:23:09 deraadt Exp $ */
2 /* $NetBSD: rarp.c,v 1.13 1996/10/13 02:29:05 christos Exp $ */
3
4 /*
5 * Copyright (c) 1992 Regents of the University of California.
6 * All rights reserved.
7 *
8 * This software was developed by the Computer Systems Engineering group
9 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
10 * contributed to Berkeley.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Lawrence Berkeley Laboratory and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 * @(#) Header: arp.c,v 1.5 93/07/15 05:52:26 leres Exp (LBL)
41 */
42 #include <sys/param.h>
43 #include <sys/socket.h>
44 #include <net/if.h>
45 #include <netinet/in.h>
46
47 #include <netinet/if_ether.h>
48 #include <netinet/in_systm.h>
49
50 #include "stand.h"
51 #include "net.h"
52 #include "netif.h"
53
54 static ssize_t rarpsend(struct iodesc *, void *, size_t);
55 static ssize_t rarprecv(struct iodesc *, void *, size_t, time_t);
56
57 /*
58 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826).
59 */
60 int
61 rarp_getipaddress(int sock)
62 {
63 struct iodesc *d;
64 struct ether_arp *ap;
65 struct {
66 u_char header[ETHER_SIZE];
67 struct {
68 struct ether_arp arp;
69 u_char pad[18]; /* 60 - sizeof(arp) */
70 } data;
71 } wbuf;
72 struct {
73 u_char header[ETHER_SIZE];
74 struct {
75 struct ether_arp arp;
76 u_char pad[24]; /* extra space */
77 } data;
78 } rbuf;
79
80 #ifdef RARP_DEBUG
81 if (debug)
82 printf("rarp: socket=%d\n", sock);
83 #endif
84 if (!(d = socktodesc(sock))) {
85 printf("rarp: bad socket. %d\n", sock);
86 return (-1);
87 }
88 #ifdef RARP_DEBUG
89 if (debug)
90 printf("rarp: d=%x\n", (u_int)d);
91 #endif
92
93 bzero((char *)&wbuf.data, sizeof(wbuf.data));
94 ap = &wbuf.data.arp;
95 ap->arp_hrd = htons(ARPHRD_ETHER);
96 ap->arp_pro = htons(ETHERTYPE_IP);
97 ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */
98 ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */
99 ap->arp_op = htons(ARPOP_REVREQUEST);
100 bcopy(d->myea, ap->arp_sha, 6);
101 bcopy(d->myea, ap->arp_tha, 6);
102
103 if (sendrecv(d,
104 rarpsend, &wbuf.data, sizeof(wbuf.data),
105 rarprecv, &rbuf.data, sizeof(rbuf.data)) < 0)
106 {
107 printf("No response for RARP request\n");
108 return (-1);
109 }
110
111 ap = &rbuf.data.arp;
112 bcopy(ap->arp_tpa, (char *)&myip, sizeof(myip));
113 #if 0
114 /* XXX - Can NOT assume this is our root server! */
115 bcopy(ap->arp_spa, (char *)&rootip, sizeof(rootip));
116 #endif
117
118 /* Compute our "natural" netmask. */
119 if (IN_CLASSA(myip.s_addr))
120 netmask = IN_CLASSA_NET;
121 else if (IN_CLASSB(myip.s_addr))
122 netmask = IN_CLASSB_NET;
123 else
124 netmask = IN_CLASSC_NET;
125
126 d->myip = myip;
127 return (0);
128 }
129
130 /*
131 * Broadcast a RARP request (i.e. who knows who I am)
132 */
133 static ssize_t
134 rarpsend(struct iodesc *d, void *pkt, size_t len)
135 {
136
137 #ifdef RARP_DEBUG
138 if (debug)
139 printf("rarpsend: called\n");
140 #endif
141
142 return (sendether(d, pkt, len, bcea, ETHERTYPE_REVARP));
143 }
144
145 /*
146 * Returns 0 if this is the packet we're waiting for
147 * else -1 (and errno == 0)
148 */
149 static ssize_t
150 rarprecv(struct iodesc *d, void *pkt, size_t len, time_t tleft)
151 {
152 ssize_t n;
153 struct ether_arp *ap;
154 u_int16_t etype; /* host order */
155
156 #ifdef RARP_DEBUG
157 if (debug)
158 printf("rarprecv: ");
159 #endif
160
161 n = readether(d, pkt, len, tleft, &etype);
162 errno = 0; /* XXX */
163 if (n < 0 || (size_t)n < sizeof(struct ether_arp)) {
164 #ifdef RARP_DEBUG
165 if (debug)
166 printf("bad len=%d\n", n);
167 #endif
168 return (-1);
169 }
170
171 if (etype != ETHERTYPE_REVARP) {
172 #ifdef RARP_DEBUG
173 if (debug)
174 printf("bad type=0x%x\n", etype);
175 #endif
176 return (-1);
177 }
178
179 ap = (struct ether_arp *)pkt;
180 if (ap->arp_hrd != htons(ARPHRD_ETHER) ||
181 ap->arp_pro != htons(ETHERTYPE_IP) ||
182 ap->arp_hln != sizeof(ap->arp_sha) ||
183 ap->arp_pln != sizeof(ap->arp_spa) )
184 {
185 #ifdef RARP_DEBUG
186 if (debug)
187 printf("bad hrd/pro/hln/pln\n");
188 #endif
189 return (-1);
190 }
191
192 if (ap->arp_op != htons(ARPOP_REVREPLY)) {
193 #ifdef RARP_DEBUG
194 if (debug)
195 printf("bad op=0x%x\n", ntohs(ap->arp_op));
196 #endif
197 return (-1);
198 }
199
200 /* Is the reply for our Ethernet address? */
201 if (bcmp(ap->arp_tha, d->myea, 6)) {
202 #ifdef RARP_DEBUG
203 if (debug)
204 printf("unwanted address\n");
205 #endif
206 return (-1);
207 }
208
209 /* We have our answer. */
210 #ifdef RARP_DEBUG
211 if (debug)
212 printf("got it\n");
213 #endif
214 return (n);
215 }