1 /* $NetBSD: rarp.c,v 1.16 1997/07/07 15:52:52 drochner 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 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#) Header: arp.c,v 1.5 93/07/15 05:52:26 leres Exp (LBL)
36 */
37
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 #include <sys/param.h>
42 #include <sys/socket.h>
43 #include <net/if.h>
44 #include <netinet/in.h>
45 #include <netinet/if_ether.h>
46
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
56 static ssize_t rarpsend(struct iodesc *, void *, size_t);
57 static ssize_t rarprecv(struct iodesc *, void *, size_t, time_t);
58
59 /*
60 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826).
61 */
62 int
rarp_getipaddress(sock)63 rarp_getipaddress(sock)
64 int sock;
65 {
66 struct iodesc *d;
67 struct ether_arp *ap;
68 struct {
69 u_char header[ETHER_SIZE];
70 struct {
71 struct ether_arp arp;
72 u_char pad[18]; /* 60 - sizeof(arp) */
73 } data;
74 } wbuf;
75 struct {
76 u_char header[ETHER_SIZE];
77 struct {
78 struct ether_arp arp;
79 u_char pad[24]; /* extra space */
80 } data;
81 } rbuf;
82
83 #ifdef RARP_DEBUG
84 if (debug)
85 printf("rarp: socket=%d\n", sock);
86 #endif
87 if (!(d = socktodesc(sock))) {
88 printf("rarp: bad socket. %d\n", sock);
89 return (-1);
90 }
91 #ifdef RARP_DEBUG
92 if (debug)
93 printf("rarp: d=%x\n", (u_int)d);
94 #endif
95
96 bzero((char*)&wbuf.data, sizeof(wbuf.data));
97 ap = &wbuf.data.arp;
98 ap->arp_hrd = htons(ARPHRD_ETHER);
99 ap->arp_pro = htons(ETHERTYPE_IP);
100 ap->arp_hln = sizeof(ap->arp_sha); /* hardware address length */
101 ap->arp_pln = sizeof(ap->arp_spa); /* protocol address length */
102 ap->arp_op = htons(ARPOP_REVREQUEST);
103 bcopy(d->myea, ap->arp_sha, 6);
104 bcopy(d->myea, ap->arp_tha, 6);
105
106 if (sendrecv(d,
107 rarpsend, &wbuf.data, sizeof(wbuf.data),
108 rarprecv, &rbuf.data, sizeof(rbuf.data)) < 0)
109 {
110 printf("No response for RARP request\n");
111 return (-1);
112 }
113
114 ap = &rbuf.data.arp;
115 bcopy(ap->arp_tpa, (char *)&myip, sizeof(myip));
116 #if 0
117 /* XXX - Can NOT assume this is our root server! */
118 bcopy(ap->arp_spa, (char *)&rootip, sizeof(rootip));
119 #endif
120
121 /* Compute our "natural" netmask. */
122 if (IN_CLASSA(myip.s_addr))
123 netmask = IN_CLASSA_NET;
124 else if (IN_CLASSB(myip.s_addr))
125 netmask = IN_CLASSB_NET;
126 else
127 netmask = IN_CLASSC_NET;
128
129 d->myip = myip;
130 return (0);
131 }
132
133 /*
134 * Broadcast a RARP request (i.e. who knows who I am)
135 */
136 static ssize_t
rarpsend(d,pkt,len)137 rarpsend(d, pkt, len)
138 struct iodesc *d;
139 void *pkt;
140 size_t len;
141 {
142
143 #ifdef RARP_DEBUG
144 if (debug)
145 printf("rarpsend: called\n");
146 #endif
147
148 return (sendether(d, pkt, len, bcea, ETHERTYPE_REVARP));
149 }
150
151 /*
152 * Returns 0 if this is the packet we're waiting for
153 * else -1 (and errno == 0)
154 */
155 static ssize_t
rarprecv(d,pkt,len,tleft)156 rarprecv(d, pkt, len, tleft)
157 struct iodesc *d;
158 void *pkt;
159 size_t len;
160 time_t tleft;
161 {
162 ssize_t n;
163 struct ether_arp *ap;
164 u_int16_t etype; /* host order */
165
166 #ifdef RARP_DEBUG
167 if (debug)
168 printf("rarprecv: ");
169 #endif
170
171 n = readether(d, pkt, len, tleft, &etype);
172 errno = 0; /* XXX */
173 if (n == -1 || n < sizeof(struct ether_arp)) {
174 #ifdef RARP_DEBUG
175 if (debug)
176 printf("bad len=%d\n", n);
177 #endif
178 return (-1);
179 }
180
181 if (etype != ETHERTYPE_REVARP) {
182 #ifdef RARP_DEBUG
183 if (debug)
184 printf("bad type=0x%x\n", etype);
185 #endif
186 return (-1);
187 }
188
189 ap = (struct ether_arp *)pkt;
190 if (ap->arp_hrd != htons(ARPHRD_ETHER) ||
191 ap->arp_pro != htons(ETHERTYPE_IP) ||
192 ap->arp_hln != sizeof(ap->arp_sha) ||
193 ap->arp_pln != sizeof(ap->arp_spa) )
194 {
195 #ifdef RARP_DEBUG
196 if (debug)
197 printf("bad hrd/pro/hln/pln\n");
198 #endif
199 return (-1);
200 }
201
202 if (ap->arp_op != htons(ARPOP_REVREPLY)) {
203 #ifdef RARP_DEBUG
204 if (debug)
205 printf("bad op=0x%x\n", ntohs(ap->arp_op));
206 #endif
207 return (-1);
208 }
209
210 /* Is the reply for our Ethernet address? */
211 if (bcmp(ap->arp_tha, d->myea, 6)) {
212 #ifdef RARP_DEBUG
213 if (debug)
214 printf("unwanted address\n");
215 #endif
216 return (-1);
217 }
218
219 /* We have our answer. */
220 #ifdef RARP_DEBUG
221 if (debug)
222 printf("got it\n");
223 #endif
224 return (n);
225 }
226