libexec/rbootd/bpf.c

   1 /*
   2  * Copyright (c) 1988, 1992 The University of Utah and the Center
   3  *      for Software Science (CSS).
   4  * Copyright (c) 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * the Center for Software Science of the University of Utah Computer
   9  * Science Department.  CSS requests users of this software to return
  10  * to css-dist@cs.utah.edu any improvements that they make and grant
  11  * CSS redistribution rights.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  *      from: @(#)bpf.c 8.1 (Berkeley) 6/4/93
  38  *
  39  * From: Utah Hdr: bpf.c 3.1 92/07/06
  40  * Author: Jeff Forys, University of Utah CSS
  41  *
  42  * @(#)bpf.c    8.1 (Berkeley) 6/4/93
  43  * $FreeBSD: src/libexec/rbootd/bpf.c,v 1.10 1999/08/28 00:09:44 peter Exp $
  44  */
  45
  46 #include <sys/param.h>
  47 #include <sys/ioctl.h>
  48 #include <sys/socket.h>
  49 #include <sys/time.h>
  50
  51 #include <net/if.h>
  52 #include <net/bpf.h>
  53
  54 #include <ctype.h>
  55 #include <errno.h>
  56 #include <fcntl.h>
  57 #include <stdio.h>
  58 #include <stdlib.h>
  59 #include <string.h>
  60 #include <syslog.h>
  61 #include <unistd.h>
  62 #include "defs.h"
  63 #include "pathnames.h"
  64
  65 static int BpfFd = -1;
  66 static unsigned BpfLen = 0;
  67 static u_int8_t *BpfPkt = NULL;
  68
  69 /*
  70 **  BpfOpen -- Open and initialize a BPF device.
  71 **
  72 **      Parameters:
  73 **              None.
  74 **
  75 **      Returns:
  76 **              File descriptor of opened BPF device (for select() etc).
  77 **
  78 **      Side Effects:
  79 **              If an error is encountered, the program terminates here.
  80 */
  81 int
  82 BpfOpen(void)
  83 {
  84         struct ifreq ifr;
  85         char bpfdev[32];
  86         int n = 0;
  87
  88         /*
  89          *  Open the first available BPF device.
  90          */
  91         do {
  92                 (void) sprintf(bpfdev, _PATH_BPF, n++);
  93                 BpfFd = open(bpfdev, O_RDWR);
  94         } while (BpfFd < 0 && (errno == EBUSY || errno == EPERM));
  95
  96         if (BpfFd < 0) {
  97                 syslog(LOG_ERR, "bpf: no available devices: %m");
  98                 Exit(0);
  99         }
 100
 101         /*
 102          *  Set interface name for bpf device, get data link layer
 103          *  type and make sure it's type Ethernet.
 104          */
 105         (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
 106         if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
 107                 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
 108                 Exit(0);
 109         }
 110
 111         /*
 112          *  Make sure we are dealing with an Ethernet device.
 113          */
 114         if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
 115                 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
 116                 Exit(0);
 117         }
 118         if (n != DLT_EN10MB) {
 119                 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
 120                        IntfName, n);
 121                 Exit(0);
 122         }
 123
 124         /*
 125          *  On read(), return packets immediately (do not buffer them).
 126          */
 127         n = 1;
 128         if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
 129                 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
 130                 Exit(0);
 131         }
 132
 133         /*
 134          *  Try to enable the chip/driver's multicast address filter to
 135          *  grab our RMP address.  If this fails, try promiscuous mode.
 136          *  If this fails, there's no way we are going to get any RMP
 137          *  packets so just exit here.
 138          */
 139 #ifdef MSG_EOR
 140         ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
 141 #endif
 142         ifr.ifr_addr.sa_family = AF_UNSPEC;
 143         memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN);
 144         if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) {
 145                 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m");
 146                 Exit(0);
 147         }
 148
 149         /*
 150          *  Ask BPF how much buffer space it requires and allocate one.
 151          */
 152         if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) {
 153                 syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m");
 154                 Exit(0);
 155         }
 156         if (BpfPkt == NULL)
 157                 BpfPkt = (u_int8_t *)malloc(BpfLen);
 158
 159         if (BpfPkt == NULL) {
 160                 syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)",
 161                        BpfLen);
 162                 Exit(0);
 163         }
 164
 165         /*
 166          *  Write a little program to snarf RMP Boot packets and stuff
 167          *  it down BPF's throat (i.e. set up the packet filter).
 168          */
 169         {
 170 #define RMP     ((struct rmp_packet *)0)
 171                 static struct bpf_insn bpf_insn[] = {
 172                     { BPF_LD|BPF_B|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dsap },
 173                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP },
 174                     { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.cntrl },
 175                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP },
 176                     { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dxsap },
 177                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP },
 178                     { BPF_RET|BPF_K,         0, 0, RMP_MAX_PACKET },
 179                     { BPF_RET|BPF_K,         0, 0, 0x0 }
 180                 };
 181 #undef  RMP
 182                 static struct bpf_program bpf_pgm = {
 183                     NELEM(bpf_insn), bpf_insn
 184                 };
 185
 186                 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) {
 187                         syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m");
 188                         Exit(0);
 189                 }
 190         }
 191
 192         return(BpfFd);
 193 }
 194
 195 /*
 196 **  BPF GetIntfName -- Return the name of a network interface attached to
 197 **              the system, or 0 if none can be found.  The interface
 198 **              must be configured up; the lowest unit number is
 199 **              preferred; loopback is ignored.
 200 **
 201 **      Parameters:
 202 **              errmsg - if no network interface found, *errmsg explains why.
 203 **
 204 **      Returns:
 205 **              A (static) pointer to interface name, or NULL on error.
 206 **
 207 **      Side Effects:
 208 **              None.
 209 */
 210 char *
 211 BpfGetIntfName(char **errmsg)
 212 {
 213         struct ifreq ibuf[8], *ifrp, *ifend, *mp;
 214         struct ifconf ifc;
 215         int fd;
 216         int minunit, n;
 217         char *cp;
 218         static char device[sizeof(ifrp->ifr_name)];
 219         static char errbuf[128] = "No Error!";
 220
 221         if (errmsg != NULL)
 222                 *errmsg = errbuf;
 223
 224         if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 225                 (void) strcpy(errbuf, "bpf: socket: %m");
 226                 return(NULL);
 227         }
 228         ifc.ifc_len = sizeof ibuf;
 229         ifc.ifc_buf = (caddr_t)ibuf;
 230
 231         if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
 232             ifc.ifc_len < sizeof(struct ifreq)) {
 233                 (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFCONF): %m");
 234                 return(NULL);
 235         }
 236         ifrp = ibuf;
 237         ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
 238
 239         mp = NULL;
 240         minunit = 666;
 241         for (; ifrp < ifend; ++ifrp) {
 242                 if (ioctl(fd, SIOCGIFFLAGS, (char *)ifrp) < 0) {
 243                         (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFFLAGS): %m");
 244                         return(NULL);
 245                 }
 246
 247                 /*
 248                  *  If interface is down or this is the loopback interface,
 249                  *  ignore it.
 250                  */
 251                 if ((ifrp->ifr_flags & IFF_UP) == 0 ||
 252 #ifdef IFF_LOOPBACK
 253                     (ifrp->ifr_flags & IFF_LOOPBACK))
 254 #else
 255                     (strcmp(ifrp->ifr_name, "lo0") == 0))
 256 #endif
 257                         continue;
 258
 259                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 260                         ;
 261                 n = atoi(cp);
 262                 if (n < minunit) {
 263                         minunit = n;
 264                         mp = ifrp;
 265                 }
 266         }
 267
 268         (void) close(fd);
 269         if (mp == NULL) {
 270                 (void) strcpy(errbuf, "bpf: no interfaces found");
 271                 return(NULL);
 272         }
 273
 274         (void) strcpy(device, mp->ifr_name);
 275         return(device);
 276 }
 277
 278 /*
 279 **  BpfRead -- Read packets from a BPF device and fill in `rconn'.
 280 **
 281 **      Parameters:
 282 **              rconn - filled in with next packet.
 283 **              doread - is True if we can issue a read() syscall.
 284 **
 285 **      Returns:
 286 **              True if `rconn' contains a new packet, False otherwise.
 287 **
 288 **      Side Effects:
 289 **              None.
 290 */
 291 int
 292 BpfRead(RMPCONN *rconn, int doread)
 293 {
 294         int datlen, caplen, hdrlen;
 295         static u_int8_t *bp = NULL, *ep = NULL;
 296         int cc;
 297
 298         /*
 299          *  The read() may block, or it may return one or more packets.
 300          *  We let the caller decide whether or not we can issue a read().
 301          */
 302         if (doread) {
 303                 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
 304                         syslog(LOG_ERR, "bpf: read: %m");
 305                         return(0);
 306                 } else {
 307                         bp = BpfPkt;
 308                         ep = BpfPkt + cc;
 309                 }
 310         }
 311
 312 #define bhp ((struct bpf_hdr *)bp)
 313         /*
 314          *  If there is a new packet in the buffer, stuff it into `rconn'
 315          *  and return a success indication.
 316          */
 317         if (bp < ep) {
 318                 datlen = bhp->bh_datalen;
 319                 caplen = bhp->bh_caplen;
 320                 hdrlen = bhp->bh_hdrlen;
 321
 322                 if (caplen != datlen)
 323                         syslog(LOG_ERR,
 324                                "bpf: short packet dropped (%d of %d bytes)",
 325                                caplen, datlen);
 326                 else if (caplen > sizeof(struct rmp_packet))
 327                         syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
 328                                caplen);
 329                 else {
 330                         rconn->rmplen = caplen;
 331                         memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
 332                               sizeof(struct timeval));
 333                         memmove((char *)&rconn->rmp, (char *)bp + hdrlen, caplen);
 334                 }
 335                 bp += BPF_WORDALIGN(caplen + hdrlen);
 336                 return(1);
 337         }
 338 #undef bhp
 339
 340         return(0);
 341 }
 342
 343 /*
 344 **  BpfWrite -- Write packet to BPF device.
 345 **
 346 **      Parameters:
 347 **              rconn - packet to send.
 348 **
 349 **      Returns:
 350 **              True if write succeeded, False otherwise.
 351 **
 352 **      Side Effects:
 353 **              None.
 354 */
 355 int
 356 BpfWrite(RMPCONN *rconn)
 357 {
 358         if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) {
 359                 syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn));
 360                 return(0);
 361         }
 362
 363         return(1);
 364 }
 365
 366 /*
 367 **  BpfClose -- Close a BPF device.
 368 **
 369 **      Parameters:
 370 **              None.
 371 **
 372 **      Returns:
 373 **              Nothing.
 374 **
 375 **      Side Effects:
 376 **              None.
 377 */
 378 void
 379 BpfClose(void)
 380 {
 381         struct ifreq ifr;
 382
 383         if (BpfPkt != NULL) {
 384                 free((char *)BpfPkt);
 385                 BpfPkt = NULL;
 386         }
 387
 388         if (BpfFd == -1)
 389                 return;
 390
 391 #ifdef MSG_EOR
 392         ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
 393 #endif
 394         ifr.ifr_addr.sa_family = AF_UNSPEC;
 395         memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN);
 396         if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0)
 397                 (void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0);
 398
 399         (void) close(BpfFd);
 400         BpfFd = -1;
 401 }