1 /* $NetBSD: bpf.c,v 1.22 2022/09/03 07:45:08 tsutsui Exp $ */
2
3 /*
4 * Copyright (c) 1988, 1992 The University of Utah and the Center
5 * for Software Science (CSS).
6 * Copyright (c) 1992, 1993
7 * The Regents of the University of California. All rights reserved.
8 *
9 * This code is derived from software contributed to Berkeley by
10 * the Center for Software Science of the University of Utah Computer
11 * Science Department. CSS requests users of this software to return
12 * to css-dist@cs.utah.edu any improvements that they make and grant
13 * CSS redistribution rights.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. 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 * from: @(#)bpf.c 8.1 (Berkeley) 6/4/93
40 *
41 * From: Utah Hdr: bpf.c 3.1 92/07/06
42 * Author: Jeff Forys, University of Utah CSS
43 */
44
45 #include <sys/cdefs.h>
46 #ifndef lint
47 #if 0
48 static char sccsid[] = "@(#)bpf.c 8.1 (Berkeley) 6/4/93";
49 #else
50 __RCSID("$NetBSD: bpf.c,v 1.22 2022/09/03 07:45:08 tsutsui Exp $");
51 #endif
52 #endif /* not lint */
53
54 #include <sys/param.h>
55 #include <sys/ioctl.h>
56 #include <sys/socket.h>
57
58 #include <net/if.h>
59 #include <net/bpf.h>
60
61 #include <ctype.h>
62 #include <errno.h>
63 #include <fcntl.h>
64 #include <stdio.h>
65 #include <stdlib.h>
66 #include <string.h>
67 #include <syslog.h>
68 #include <paths.h>
69 #include <unistd.h>
70 #include <ifaddrs.h>
71 #include "defs.h"
72 #include "pathnames.h"
73
74 static int BpfFd = -1;
75 static unsigned BpfLen = 0;
76 static u_int8_t *BpfPkt = NULL;
77
78 /*
79 ** BpfOpen -- Open and initialize a BPF device.
80 **
81 ** Parameters:
82 ** None.
83 **
84 ** Returns:
85 ** File descriptor of opened BPF device (for select() etc).
86 **
87 ** Side Effects:
88 ** If an error is encountered, the program terminates here.
89 */
90 int
BpfOpen(void)91 BpfOpen(void)
92 {
93 struct ifreq ifr;
94 u_int bufsize = 32768;
95 int n;
96
97 BpfFd = open(_PATH_BPF, O_RDWR);
98 if (BpfFd < 0) {
99 syslog(LOG_ERR, "bpf: no available devices: %m");
100 Exit(0);
101 }
102
103 if (ioctl(BpfFd, BIOCSBLEN, &bufsize) < 0) {
104 syslog(LOG_ERR, "bpf: ioctl(BIOCSBLEN,%d): %m", bufsize);
105 }
106
107 /*
108 * Set interface name for bpf device, get data link layer
109 * type and make sure it's type Ethernet.
110 */
111 (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
112 if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
113 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
114 Exit(0);
115 }
116
117 /*
118 * Make sure we are dealing with an Ethernet device.
119 */
120 if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
121 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
122 Exit(0);
123 }
124 if (n != DLT_EN10MB) {
125 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
126 IntfName, n);
127 Exit(0);
128 }
129
130 /*
131 * On read(), return packets immediately (do not buffer them).
132 */
133 n = 1;
134 if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
135 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
136 Exit(0);
137 }
138
139 /*
140 * Try to enable the chip/driver's multicast address filter to
141 * grab our RMP address. If this fails, try promiscuous mode.
142 * If this fails, there's no way we are going to get any RMP
143 * packets so just exit here.
144 */
145 #ifdef MSG_EOR
146 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
147 #endif
148 ifr.ifr_addr.sa_family = AF_UNSPEC;
149 memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
150 RMP_ADDRLEN);
151 if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) {
152 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m");
153 Exit(0);
154 }
155
156 /*
157 * Ask BPF how much buffer space it requires and allocate one.
158 */
159 if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) {
160 syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m");
161 Exit(0);
162 }
163 if (BpfPkt == NULL)
164 BpfPkt = (u_int8_t *)malloc(BpfLen);
165
166 if (BpfPkt == NULL) {
167 syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)",
168 BpfLen);
169 Exit(0);
170 }
171
172 /*
173 * Write a little program to snarf RMP Boot packets and stuff
174 * it down BPF's throat (i.e. set up the packet filter).
175 */
176 {
177 #define RMP ((struct rmp_packet *)0)
178 static struct bpf_insn bpf_insn[] = {
179 { BPF_LD|BPF_B|BPF_ABS, 0, 0, (long)&RMP->hp_llc.dsap },
180 { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP },
181 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (long)&RMP->hp_llc.cntrl },
182 { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP },
183 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (long)&RMP->hp_llc.dxsap },
184 { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP },
185 { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET },
186 { BPF_RET|BPF_K, 0, 0, 0x0 }
187 };
188 #undef RMP
189 static struct bpf_program bpf_pgm = {
190 sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn
191 };
192
193 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) {
194 syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m");
195 Exit(0);
196 }
197 }
198
199 return(BpfFd);
200 }
201
202 /*
203 ** BPF GetIntfName -- Return the name of a network interface attached to
204 ** the system, or 0 if none can be found. The interface
205 ** must be configured up; the lowest unit number is
206 ** preferred; loopback is ignored.
207 **
208 ** Parameters:
209 ** errmsg - if no network interface found, *errmsg explains why.
210 **
211 ** Returns:
212 ** A (static) pointer to interface name, or NULL on error.
213 **
214 ** Side Effects:
215 ** None.
216 */
217 char *
BpfGetIntfName(char ** errmsg)218 BpfGetIntfName(char **errmsg)
219 {
220 struct ifaddrs *ifap, *ifa, *p;
221 int minunit, n;
222 char *cp;
223 static char device[IFNAMSIZ + 1];
224 static char errbuf[128] = "No Error!";
225
226 if (errmsg != NULL)
227 *errmsg = errbuf;
228
229 if (getifaddrs(&ifap) != 0) {
230 (void) strlcpy(errbuf, "bpf: getifaddrs: %m", sizeof(errbuf));
231 return(NULL);
232 }
233
234 p = NULL;
235 minunit = 666;
236 for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
237 /*
238 * If interface is down or this is the loopback interface,
239 * ignore it.
240 */
241 if ((ifa->ifa_flags & IFF_UP) == 0 ||
242 #ifdef IFF_LOOPBACK
243 (ifa->ifa_flags & IFF_LOOPBACK))
244 #else
245 (strcmp(ifa->ifa_name, "lo0") == 0))
246 #endif
247 continue;
248
249 for (cp = ifa->ifa_name; !isdigit((unsigned char)*cp); ++cp)
250 ;
251 n = atoi(cp);
252 if (n < minunit) {
253 minunit = n;
254 p = ifa;
255 }
256 }
257 if (p == NULL) {
258 (void) strlcpy(errbuf, "bpf: no interfaces found",
259 sizeof(errbuf));
260 freeifaddrs(ifap);
261 return(NULL);
262 }
263
264 (void) strlcpy(device, p->ifa_name, sizeof(device));
265 freeifaddrs(ifap);
266 return(device);
267 }
268
269 /*
270 ** BpfRead -- Read packets from a BPF device and fill in `rconn'.
271 **
272 ** Parameters:
273 ** rconn - filled in with next packet.
274 ** doread - is True if we can issue a read() syscall.
275 **
276 ** Returns:
277 ** True if `rconn' contains a new packet, False otherwise.
278 **
279 ** Side Effects:
280 ** None.
281 */
282 int
BpfRead(RMPCONN * rconn,int doread)283 BpfRead(RMPCONN *rconn, int doread)
284 {
285 int datlen, caplen, hdrlen;
286 static u_int8_t *bp = NULL, *ep = NULL;
287 int cc;
288
289 /*
290 * The read() may block, or it may return one or more packets.
291 * We let the caller decide whether or not we can issue a read().
292 */
293 if (doread) {
294 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
295 syslog(LOG_ERR, "bpf: read: %m");
296 return(0);
297 } else {
298 bp = BpfPkt;
299 ep = BpfPkt + cc;
300 }
301 }
302
303 #define bhp ((struct bpf_hdr *)bp)
304 /*
305 * If there is a new packet in the buffer, stuff it into `rconn'
306 * and return a success indication.
307 */
308 if (bp < ep) {
309 datlen = bhp->bh_datalen;
310 caplen = bhp->bh_caplen;
311 hdrlen = bhp->bh_hdrlen;
312
313 if (caplen != datlen)
314 syslog(LOG_ERR,
315 "bpf: short packet dropped (%d of %d bytes)",
316 caplen, datlen);
317 else if (caplen > (int)sizeof(struct rmp_packet))
318 syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
319 caplen);
320 else {
321 rconn->rmplen = caplen;
322 memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
323 sizeof(struct timeval));
324 memmove((char *)&rconn->rmp, (char *)bp + hdrlen,
325 caplen);
326 }
327 bp += BPF_WORDALIGN(caplen + hdrlen);
328 return(1);
329 }
330 #undef bhp
331
332 return(0);
333 }
334
335 /*
336 ** BpfWrite -- Write packet to BPF device.
337 **
338 ** Parameters:
339 ** rconn - packet to send.
340 **
341 ** Returns:
342 ** True if write succeeded, False otherwise.
343 **
344 ** Side Effects:
345 ** None.
346 */
347 int
BpfWrite(RMPCONN * rconn)348 BpfWrite(RMPCONN *rconn)
349 {
350 if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) {
351 syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn));
352 return(0);
353 }
354
355 return(1);
356 }
357
358 /*
359 ** BpfClose -- Close a BPF device.
360 **
361 ** Parameters:
362 ** None.
363 **
364 ** Returns:
365 ** Nothing.
366 **
367 ** Side Effects:
368 ** None.
369 */
370 void
BpfClose(void)371 BpfClose(void)
372 {
373 struct ifreq ifr;
374
375 if (BpfPkt != NULL) {
376 free((char *)BpfPkt);
377 BpfPkt = NULL;
378 }
379
380 if (BpfFd == -1)
381 return;
382
383 #ifdef MSG_EOR
384 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
385 #endif
386 ifr.ifr_addr.sa_family = AF_UNSPEC;
387 memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
388 RMP_ADDRLEN);
389 if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0)
390 (void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0);
391
392 (void) close(BpfFd);
393 BpfFd = -1;
394 }
395