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
  47 #ifndef lint
  48 #if 0
  49 static const char sccsid[] = "@(#)bpf.c 8.1 (Berkeley) 6/4/93";
  50 #endif
  51 static const char rcsid[] =
  52   "$FreeBSD$";
  53 #endif /* not lint */
  54
  55 #include <sys/param.h>
  56 #include <sys/ioctl.h>
  57 #include <sys/socket.h>
  58 #include <sys/time.h>
  59
  60 #include <net/if.h>
  61 #include <net/bpf.h>
  62
  63 #include <ctype.h>
  64 #include <errno.h>
  65 #include <fcntl.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <syslog.h>
  70 #include <unistd.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
  91 BpfOpen(void)
  92 {
  93         struct ifreq ifr;
  94         char bpfdev[32];
  95         int n = 0;
  96
  97         /*
  98          *  Open the first available BPF device.
  99          */
 100         do {
 101                 (void) sprintf(bpfdev, _PATH_BPF, n++);
 102                 BpfFd = open(bpfdev, O_RDWR);
 103         } while (BpfFd < 0 && (errno == EBUSY || errno == EPERM));
 104
 105         if (BpfFd < 0) {
 106                 syslog(LOG_ERR, "bpf: no available devices: %m");
 107                 Exit(0);
 108         }
 109
 110         /*
 111          *  Set interface name for bpf device, get data link layer
 112          *  type and make sure it's type Ethernet.
 113          */
 114         (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
 115         if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
 116                 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
 117                 Exit(0);
 118         }
 119
 120         /*
 121          *  Make sure we are dealing with an Ethernet device.
 122          */
 123         if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
 124                 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
 125                 Exit(0);
 126         }
 127         if (n != DLT_EN10MB) {
 128                 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
 129                        IntfName, n);
 130                 Exit(0);
 131         }
 132
 133         /*
 134          *  On read(), return packets immediately (do not buffer them).
 135          */
 136         n = 1;
 137         if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
 138                 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
 139                 Exit(0);
 140         }
 141
 142         /*
 143          *  Try to enable the chip/driver's multicast address filter to
 144          *  grab our RMP address.  If this fails, try promiscuous mode.
 145          *  If this fails, there's no way we are going to get any RMP
 146          *  packets so just exit here.
 147          */
 148 #ifdef MSG_EOR
 149         ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
 150 #endif
 151         ifr.ifr_addr.sa_family = AF_UNSPEC;
 152         memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN);
 153         if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) {
 154                 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m");
 155                 Exit(0);
 156         }
 157
 158         /*
 159          *  Ask BPF how much buffer space it requires and allocate one.
 160          */
 161         if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) {
 162                 syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m");
 163                 Exit(0);
 164         }
 165         if (BpfPkt == NULL)
 166                 BpfPkt = (u_int8_t *)malloc(BpfLen);
 167
 168         if (BpfPkt == NULL) {
 169                 syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)",
 170                        BpfLen);
 171                 Exit(0);
 172         }
 173
 174         /*
 175          *  Write a little program to snarf RMP Boot packets and stuff
 176          *  it down BPF's throat (i.e. set up the packet filter).
 177          */
 178         {
 179 #define RMP     ((struct rmp_packet *)0)
 180                 static struct bpf_insn bpf_insn[] = {
 181                     { BPF_LD|BPF_B|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dsap },
 182                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP },
 183                     { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.cntrl },
 184                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP },
 185                     { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dxsap },
 186                     { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP },
 187                     { BPF_RET|BPF_K,         0, 0, RMP_MAX_PACKET },
 188                     { BPF_RET|BPF_K,         0, 0, 0x0 }
 189                 };
 190 #undef  RMP
 191                 static struct bpf_program bpf_pgm = {
 192                     sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn
 193                 };
 194
 195                 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) {
 196                         syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m");
 197                         Exit(0);
 198                 }
 199         }
 200
 201         return(BpfFd);
 202 }
 203
 204 /*
 205 **  BPF GetIntfName -- Return the name of a network interface attached to
 206 **              the system, or 0 if none can be found.  The interface
 207 **              must be configured up; the lowest unit number is
 208 **              preferred; loopback is ignored.
 209 **
 210 **      Parameters:
 211 **              errmsg - if no network interface found, *errmsg explains why.
 212 **
 213 **      Returns:
 214 **              A (static) pointer to interface name, or NULL on error.
 215 **
 216 **      Side Effects:
 217 **              None.
 218 */
 219 char *
 220 BpfGetIntfName(char **errmsg)
 221 {
 222         struct ifreq ibuf[8], *ifrp, *ifend, *mp;
 223         struct ifconf ifc;
 224         int fd;
 225         int minunit, n;
 226         char *cp;
 227         static char device[sizeof(ifrp->ifr_name)];
 228         static char errbuf[128] = "No Error!";
 229
 230         if (errmsg != NULL)
 231                 *errmsg = errbuf;
 232
 233         if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
 234                 (void) strcpy(errbuf, "bpf: socket: %m");
 235                 return(NULL);
 236         }
 237         ifc.ifc_len = sizeof ibuf;
 238         ifc.ifc_buf = (caddr_t)ibuf;
 239
 240 #ifdef OSIOCGIFCONF
 241         if (ioctl(fd, OSIOCGIFCONF, (char *)&ifc) < 0 ||
 242             ifc.ifc_len < sizeof(struct ifreq)) {
 243                 (void) strcpy(errbuf, "bpf: ioctl(OSIOCGIFCONF): %m");
 244                 return(NULL);
 245         }
 246 #else
 247         if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
 248             ifc.ifc_len < sizeof(struct ifreq)) {
 249                 (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFCONF): %m");
 250                 return(NULL);
 251         }
 252 #endif
 253         ifrp = ibuf;
 254         ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
 255
 256         mp = 0;
 257         minunit = 666;
 258         for (; ifrp < ifend; ++ifrp) {
 259                 if (ioctl(fd, SIOCGIFFLAGS, (char *)ifrp) < 0) {
 260                         (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFFLAGS): %m");
 261                         return(NULL);
 262                 }
 263
 264                 /*
 265                  *  If interface is down or this is the loopback interface,
 266                  *  ignore it.
 267                  */
 268                 if ((ifrp->ifr_flags & IFF_UP) == 0 ||
 269 #ifdef IFF_LOOPBACK
 270                     (ifrp->ifr_flags & IFF_LOOPBACK))
 271 #else
 272                     (strcmp(ifrp->ifr_name, "lo0") == 0))
 273 #endif
 274                         continue;
 275
 276                 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
 277                         ;
 278                 n = atoi(cp);
 279                 if (n < minunit) {
 280                         minunit = n;
 281                         mp = ifrp;
 282                 }
 283         }
 284
 285         (void) close(fd);
 286         if (mp == 0) {
 287                 (void) strcpy(errbuf, "bpf: no interfaces found");
 288                 return(NULL);
 289         }
 290
 291         (void) strcpy(device, mp->ifr_name);
 292         return(device);
 293 }
 294
 295 /*
 296 **  BpfRead -- Read packets from a BPF device and fill in `rconn'.
 297 **
 298 **      Parameters:
 299 **              rconn - filled in with next packet.
 300 **              doread - is True if we can issue a read() syscall.
 301 **
 302 **      Returns:
 303 **              True if `rconn' contains a new packet, False otherwise.
 304 **
 305 **      Side Effects:
 306 **              None.
 307 */
 308 int
 309 BpfRead(RMPCONN *rconn, int doread)
 310 {
 311         int datlen, caplen, hdrlen;
 312         static u_int8_t *bp = NULL, *ep = NULL;
 313         int cc;
 314
 315         /*
 316          *  The read() may block, or it may return one or more packets.
 317          *  We let the caller decide whether or not we can issue a read().
 318          */
 319         if (doread) {
 320                 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
 321                         syslog(LOG_ERR, "bpf: read: %m");
 322                         return(0);
 323                 } else {
 324                         bp = BpfPkt;
 325                         ep = BpfPkt + cc;
 326                 }
 327         }
 328
 329 #define bhp ((struct bpf_hdr *)bp)
 330         /*
 331          *  If there is a new packet in the buffer, stuff it into `rconn'
 332          *  and return a success indication.
 333          */
 334         if (bp < ep) {
 335                 datlen = bhp->bh_datalen;
 336                 caplen = bhp->bh_caplen;
 337                 hdrlen = bhp->bh_hdrlen;
 338
 339                 if (caplen != datlen)
 340                         syslog(LOG_ERR,
 341                                "bpf: short packet dropped (%d of %d bytes)",
 342                                caplen, datlen);
 343                 else if (caplen > sizeof(struct rmp_packet))
 344                         syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
 345                                caplen);
 346                 else {
 347                         rconn->rmplen = caplen;
 348                         memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
 349                               sizeof(struct timeval));
 350                         memmove((char *)&rconn->rmp, (char *)bp + hdrlen, caplen);
 351                 }
 352                 bp += BPF_WORDALIGN(caplen + hdrlen);
 353                 return(1);
 354         }
 355 #undef bhp
 356
 357         return(0);
 358 }
 359
 360 /*
 361 **  BpfWrite -- Write packet to BPF device.
 362 **
 363 **      Parameters:
 364 **              rconn - packet to send.
 365 **
 366 **      Returns:
 367 **              True if write succeeded, False otherwise.
 368 **
 369 **      Side Effects:
 370 **              None.
 371 */
 372 int
 373 BpfWrite(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(void)
 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 }