1 /* $NetBSD: rarp.c,v 1.34 2019/04/05 20:09:29 christos 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 */
66 struct 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
79 static ssize_t rarpsend(struct iodesc *, void *, size_t);
80 static ssize_t rarprecv(struct iodesc *, void *, size_t, saseconds_t);
81
82 /*
83 * Ethernet (Reverse) Address Resolution Protocol (see RFC 903, and 826).
84 */
85 int
rarp_getipaddress(int sock)86 rarp_getipaddress(int sock)
87 {
88 struct iodesc *d;
89 struct ether_arp *ap;
90 struct {
91 u_char header[ETHERNET_HEADER_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[ETHERNET_HEADER_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("%s: socket=%d\n", __func__, sock);
108 #endif
109 if (!(d = socktodesc(sock))) {
110 printf("%s: bad socket. %d\n", __func__, sock);
111 return -1;
112 }
113 #ifdef RARP_DEBUG
114 if (debug)
115 printf("%s: d=%p\n", __func__, 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, ETHER_ADDR_LEN);
126 (void)memcpy(ap->arp_tha, d->myea, ETHER_ADDR_LEN);
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 */
158 static ssize_t
rarpsend(struct iodesc * d,void * pkt,size_t len)159 rarpsend(struct iodesc *d, void *pkt, size_t len)
160 {
161
162 #ifdef RARP_DEBUG
163 if (debug)
164 printf("%s: called\n", __func__);
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 */
174 static ssize_t
rarprecv(struct iodesc * d,void * pkt,size_t len,saseconds_t tleft)175 rarprecv(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("%s: ", __func__);
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, ETHER_ADDR_LEN)) {
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