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. All advertising materials mentioning features or use of this software
  22  *    must display the following acknowledgement:
  23  *      This product includes software developed by the University of
  24  *      California, Berkeley and its contributors.
  25  * 4. Neither the name of the University nor the names of its contributors
  26  *    may be used to endorse or promote products derived from this software
  27  *    without specific prior written permission.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  39  * SUCH DAMAGE.
  40  *
  41  *      from: @(#)bpf.c 8.1 (Berkeley) 6/4/93
  42  *
  43  * From: Utah Hdr: bpf.c 3.1 92/07/06
  44  * Author: Jeff Forys, University of Utah CSS
  45  *
  46  * @(#)bpf.c    8.1 (Berkeley) 6/4/93
  47  * $FreeBSD: src/libexec/rbootd/bpf.c,v 1.10 1999/08/28 00:09:44 peter Exp $
  48  * $DragonFly: src/libexec/rbootd/bpf.c,v 1.2 2003/06/17 04:27:07 dillon Exp $
  49  */
  50
  51 #include <sys/param.h>
  52 #include <sys/ioctl.h>
  53 #include <sys/socket.h>
  54 #include <sys/time.h>
  55
  56 #include <net/if.h>
  57 #include <net/bpf.h>
  58
  59 #include <ctype.h>
  60 #include <errno.h>
  61 #include <fcntl.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <syslog.h>
  66 #include <unistd.h>
  67 #include "defs.h"
  68 #include "pathnames.h"
  69
  70 static int BpfFd = -1;
  71 static unsigned BpfLen = 0;
  72 static u_int8_t *BpfPkt = NULL;
  73
  74 /*
  75 **  BpfOpen -- Open and initialize a BPF device.
  76 **
  77 **      Parameters:
  78 **              None.
  79 **
  80 **      Returns:
  81 **              File descriptor of opened BPF device (for select() etc).
  82 **
  83 **      Side Effects:
  84 **              If an error is encountered, the program terminates here.
  85 */
  86 int
  87 BpfOpen()
  88 {
  89         struct ifreq ifr;
  90         char bpfdev[32];
  91         int n = 0;
  92
  93         /*
  94          *  Open the first available BPF device.
  95          */
  96         do {
  97                 (void) sprintf(bpfdev, _PATH_BPF, n++);
  98                 BpfFd = open(bpfdev, O_RDWR);
  99         } while (BpfFd < 0 && (errno == EBUSY || errno == EPERM));
 100
 101         if (BpfFd < 0) {
 102                 syslog(LOG_ERR, "bpf: no available devices: %m");
 103                 Exit(0);
 104         }
 105
 106         /*
 107          *  Set interface name for bpf device, get data link layer
 108          *  type and make sure it's type Ethernet.
 109          */
 110         (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
 111         if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
 112                 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
 113                 Exit(0);
 114         }
 115
 116         /*
 117          *  Make sure we are dealing with an Ethernet device.
 118          */
 119         if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
 120                 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
 121                 Exit(0);
 122         }
 123         if (n != DLT_EN10MB) {
 124                 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
 125                        IntfName, n);
 126                 Exit(0);
 127         }
 128
 129         /*
 130          *  On read(), return packets immediately (do not buffer them).
 131          */
 132         n = 1;
 133         if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
 134                 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
 135                 Exit(0);
 136         }
 137
 138         /*
 139          *  Try to enable the chip/driver's multicast address filter to
 140          *  grab our RMP address.  If this fails, try promiscuous mode.
 141          *  If this fails, there's no way we are going to get any RMP
 142          *  packets so just exit here.
 143          */
 144 #ifdef MSG_EOR
 145         ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
 146 #endif
 147         ifr.ifr_addr.sa_family = AF_UNSPEC;
 148         memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN);
 149         if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) {
 150                 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m");
 151                 Exit(0);
 152         }
 153
 154         /*
 155          *  Ask BPF how much buffer space it requires and allocate one.
 156          */
 157         if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) {
 158                 syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m");
 159                 Exit(0);
 160         }
 161         if (BpfPkt == NULL)
 162                 BpfPkt = (u_int8_t *)malloc(BpfLen);
 163
 164         if (BpfPkt == NULL) {
 165                 syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)",
 166                        BpfLen);
 167                 Exit(0);
 168         }
 169
 170         /*
 171          *  Write a little program to snarf RMP Boot packets and stuff
 172          *  it down BPF's throat (i.e. set up the packet filter).
 173          */
 174         {
 175 #define RMP     ((struct rmp_packet *)0)
 176                 static struct bpf_insn bpf_insn[] = {
 177                     { BPF_LD|BPF_B|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dsap },
 178                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP },
 179                     { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.cntrl },
 180                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP },
 181                     { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dxsap },
 182                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP },
 183                     { BPF_RET|BPF_K,         0, 0, RMP_MAX_PACKET },
 184                     { BPF_RET|BPF_K,         0, 0, 0x0 }
 185                 };
 186 #undef  RMP
 187                 static struct bpf_program bpf_pgm = {
 188                     sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn
 189                 };
 190
 191                 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) {
 192                         syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m");
 193                         Exit(0);
 194                 }
 195         }
 196
 197         return(BpfFd);
 198 }
 199
 200 /*
 201 **  BPF GetIntfName -- Return the name of a network interface attached to
 202 **              the system, or 0 if none can be found.  The interface
 203 **              must be configured up; the lowest unit number is
 204 **              preferred; loopback is ignored.
 205 **
 206 **      Parameters:
 207 **              errmsg - if no network interface found, *errmsg explains why.
 208 **
 209 **      Returns:
 210 **              A (static) pointer to interface name, or NULL on error.
 211 **
 212 **      Side Effects:
 213 **              None.
 214 */
 215 char *
 216 BpfGetIntfName(errmsg)
 217         char **errmsg;
 218 {
 219         struct ifreq ibuf[8], *ifrp, *ifend, *mp;
 220         struct ifconf ifc;
 221         int fd;
 222         int minunit, n;
 223         char *cp;
 224         static char device[sizeof(ifrp->ifr_name)];
 225         static char errbuf[128] = "No Error!";
 226
 227         if (errmsg != NULL)
 228                 *errmsg = errbuf;
 229
 230         if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 231                 (void) strcpy(errbuf, "bpf: socket: %m");
 232                 return(NULL);
 233         }
 234         ifc.ifc_len = sizeof ibuf;
 235         ifc.ifc_buf = (caddr_t)ibuf;
 236
 237 #ifdef OSIOCGIFCONF
 238         if (ioctl(fd, OSIOCGIFCONF, (char *)&ifc) < 0 ||
 239             ifc.ifc_len < sizeof(struct ifreq)) {
 240                 (void) strcpy(errbuf, "bpf: ioctl(OSIOCGIFCONF): %m");
 241                 return(NULL);
 242         }
 243 #else
 244         if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
 245             ifc.ifc_len < sizeof(struct ifreq)) {
 246                 (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFCONF): %m");
 247                 return(NULL);
 248         }
 249 #endif
 250         ifrp = ibuf;
 251         ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
 252
 253         mp = 0;
 254         minunit = 666;
 255         for (; ifrp < ifend; ++ifrp) {
 256                 if (ioctl(fd, SIOCGIFFLAGS, (char *)ifrp) < 0) {
 257                         (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFFLAGS): %m");
 258                         return(NULL);
 259                 }
 260
 261                 /*
 262                  *  If interface is down or this is the loopback interface,
 263                  *  ignore it.
 264                  */
 265                 if ((ifrp->ifr_flags & IFF_UP) == 0 ||
 266 #ifdef IFF_LOOPBACK
 267                     (ifrp->ifr_flags & IFF_LOOPBACK))
 268 #else
 269                     (strcmp(ifrp->ifr_name, "lo0") == 0))
 270 #endif
 271                         continue;
 272
 273                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 274                         ;
 275                 n = atoi(cp);
 276                 if (n < minunit) {
 277                         minunit = n;
 278                         mp = ifrp;
 279                 }
 280         }
 281
 282         (void) close(fd);
 283         if (mp == 0) {
 284                 (void) strcpy(errbuf, "bpf: no interfaces found");
 285                 return(NULL);
 286         }
 287
 288         (void) strcpy(device, mp->ifr_name);
 289         return(device);
 290 }
 291
 292 /*
 293 **  BpfRead -- Read packets from a BPF device and fill in `rconn'.
 294 **
 295 **      Parameters:
 296 **              rconn - filled in with next packet.
 297 **              doread - is True if we can issue a read() syscall.
 298 **
 299 **      Returns:
 300 **              True if `rconn' contains a new packet, False otherwise.
 301 **
 302 **      Side Effects:
 303 **              None.
 304 */
 305 int
 306 BpfRead(rconn, doread)
 307         RMPCONN *rconn;
 308         int doread;
 309 {
 310         int datlen, caplen, hdrlen;
 311         static u_int8_t *bp = NULL, *ep = NULL;
 312         int cc;
 313
 314         /*
 315          *  The read() may block, or it may return one or more packets.
 316          *  We let the caller decide whether or not we can issue a read().
 317          */
 318         if (doread) {
 319                 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
 320                         syslog(LOG_ERR, "bpf: read: %m");
 321                         return(0);
 322                 } else {
 323                         bp = BpfPkt;
 324                         ep = BpfPkt + cc;
 325                 }
 326         }
 327
 328 #define bhp ((struct bpf_hdr *)bp)
 329         /*
 330          *  If there is a new packet in the buffer, stuff it into `rconn'
 331          *  and return a success indication.
 332          */
 333         if (bp < ep) {
 334                 datlen = bhp->bh_datalen;
 335                 caplen = bhp->bh_caplen;
 336                 hdrlen = bhp->bh_hdrlen;
 337
 338                 if (caplen != datlen)
 339                         syslog(LOG_ERR,
 340                                "bpf: short packet dropped (%d of %d bytes)",
 341                                caplen, datlen);
 342                 else if (caplen > sizeof(struct rmp_packet))
 343                         syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
 344                                caplen);
 345                 else {
 346                         rconn->rmplen = caplen;
 347                         memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
 348                               sizeof(struct timeval));
 349                         memmove((char *)&rconn->rmp, (char *)bp + hdrlen, caplen);
 350                 }
 351                 bp += BPF_WORDALIGN(caplen + hdrlen);
 352                 return(1);
 353         }
 354 #undef bhp
 355
 356         return(0);
 357 }
 358
 359 /*
 360 **  BpfWrite -- Write packet to BPF device.
 361 **
 362 **      Parameters:
 363 **              rconn - packet to send.
 364 **
 365 **      Returns:
 366 **              True if write succeeded, False otherwise.
 367 **
 368 **      Side Effects:
 369 **              None.
 370 */
 371 int
 372 BpfWrite(rconn)
 373         RMPCONN *rconn;
 374 {
 375         if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) {
 376                 syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn));
 377                 return(0);
 378         }
 379
 380         return(1);
 381 }
 382
 383 /*
 384 **  BpfClose -- Close a BPF device.
 385 **
 386 **      Parameters:
 387 **              None.
 388 **
 389 **      Returns:
 390 **              Nothing.
 391 **
 392 **      Side Effects:
 393 **              None.
 394 */
 395 void
 396 BpfClose()
 397 {
 398         struct ifreq ifr;
 399
 400         if (BpfPkt != NULL) {
 401                 free((char *)BpfPkt);
 402                 BpfPkt = NULL;
 403         }
 404
 405         if (BpfFd == -1)
 406                 return;
 407
 408 #ifdef MSG_EOR
 409         ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
 410 #endif
 411         ifr.ifr_addr.sa_family = AF_UNSPEC;
 412         memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN);
 413         if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0)
 414                 (void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0);
 415
 416         (void) close(BpfFd);
 417         BpfFd = -1;
 418 }