The Tcpdump Group git mirrors - libpcap/blob - pcap-pf.c

   1 /*
   2  * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  *
  21  * packet filter subroutines for tcpdump
  22  *      Extraction/creation by Jeffrey Mogul, DECWRL
  23  */
  24
  25 #ifndef lint
  26 static const char rcsid[] =
  27     "@(#) $Header: /tcpdump/master/libpcap/pcap-pf.c,v 1.67 2002-07-11 09:06:42 guy Exp $ (LBL)";
  28 #endif
  29
  30 #ifdef HAVE_CONFIG_H
  31 #include "config.h"
  32 #endif
  33
  34 #include <sys/types.h>
  35 #include <sys/time.h>
  36 #include <sys/timeb.h>
  37 #include <sys/socket.h>
  38 #include <sys/file.h>
  39 #include <sys/ioctl.h>
  40 #include <net/pfilt.h>
  41
  42 struct mbuf;
  43 struct rtentry;
  44 #include <net/if.h>
  45
  46 #include <netinet/in.h>
  47 #include <netinet/in_systm.h>
  48 #include <netinet/ip.h>
  49 #include <netinet/if_ether.h>
  50 #include <netinet/ip_var.h>
  51 #include <netinet/udp.h>
  52 #include <netinet/udp_var.h>
  53 #include <netinet/tcp.h>
  54 #include <netinet/tcpip.h>
  55
  56 #include <ctype.h>
  57 #include <errno.h>
  58 #include <netdb.h>
  59 #include <stdio.h>
  60 #include <stdlib.h>
  61 #include <string.h>
  62 #include <unistd.h>
  63
  64 #include "pcap-int.h"
  65
  66 #ifdef HAVE_OS_PROTO_H
  67 #include "os-proto.h"
  68 #endif
  69
  70 /*
  71  * BUFSPACE is the size in bytes of the packet read buffer.  Most tcpdump
  72  * applications aren't going to need more than 200 bytes of packet header
  73  * and the read shouldn't return more packets than packetfilter's internal
  74  * queue limit (bounded at 256).
  75  */
  76 #define BUFSPACE (200 * 256)
  77
  78 int
  79 pcap_read(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
  80 {
  81         register u_char *p, *bp;
  82         struct bpf_insn *fcode;
  83         register int cc, n, buflen, inc;
  84         register struct enstamp *sp;
  85 #ifdef LBL_ALIGN
  86         struct enstamp stamp;
  87 #endif
  88 #ifdef PCAP_FDDIPAD
  89         register int pad;
  90 #endif
  91
  92         fcode = pc->md.use_bpf ? NULL : pc->fcode.bf_insns;
  93  again:
  94         cc = pc->cc;
  95         if (cc == 0) {
  96                 cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
  97                 if (cc < 0) {
  98                         if (errno == EWOULDBLOCK)
  99                                 return (0);
 100                         if (errno == EINVAL &&
 101                             lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
 102                                 /*
 103                                  * Due to a kernel bug, after 2^31 bytes,
 104                                  * the kernel file offset overflows and
 105                                  * read fails with EINVAL. The lseek()
 106                                  * to 0 will fix things.
 107                                  */
 108                                 (void)lseek(pc->fd, 0L, SEEK_SET);
 109                                 goto again;
 110                         }
 111                         snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
 112                                 pcap_strerror(errno));
 113                         return (-1);
 114                 }
 115                 bp = pc->buffer + pc->offset;
 116         } else
 117                 bp = pc->bp;
 118         /*
 119          * Loop through each packet.
 120          */
 121         n = 0;
 122 #ifdef PCAP_FDDIPAD
 123         if (pc->linktype == DLT_FDDI)
 124                 pad = pcap_fddipad;
 125         else
 126                 pad = 0;
 127 #endif
 128         while (cc > 0) {
 129                 if (cc < sizeof(*sp)) {
 130                         snprintf(pc->errbuf, sizeof(pc->errbuf),
 131                             "pf short read (%d)", cc);
 132                         return (-1);
 133                 }
 134 #ifdef LBL_ALIGN
 135                 if ((long)bp & 3) {
 136                         sp = &stamp;
 137                         memcpy((char *)sp, (char *)bp, sizeof(*sp));
 138                 } else
 139 #endif
 140                         sp = (struct enstamp *)bp;
 141                 if (sp->ens_stamplen != sizeof(*sp)) {
 142                         snprintf(pc->errbuf, sizeof(pc->errbuf),
 143                             "pf short stamplen (%d)",
 144                             sp->ens_stamplen);
 145                         return (-1);
 146                 }
 147
 148                 p = bp + sp->ens_stamplen;
 149                 buflen = sp->ens_count;
 150                 if (buflen > pc->snapshot)
 151                         buflen = pc->snapshot;
 152
 153                 /* Calculate inc before possible pad update */
 154                 inc = ENALIGN(buflen + sp->ens_stamplen);
 155                 cc -= inc;
 156                 bp += inc;
 157 #ifdef PCAP_FDDIPAD
 158                 p += pad;
 159                 buflen -= pad;
 160 #endif
 161                 pc->md.TotPkts++;
 162                 pc->md.TotDrops += sp->ens_dropped;
 163                 pc->md.TotMissed = sp->ens_ifoverflows;
 164                 if (pc->md.OrigMissed < 0)
 165                         pc->md.OrigMissed = pc->md.TotMissed;
 166
 167                 /*
 168                  * Short-circuit evaluation: if using BPF filter
 169                  * in kernel, no need to do it now.
 170                  */
 171                 if (fcode == NULL ||
 172                     bpf_filter(fcode, p, sp->ens_count, buflen)) {
 173                         struct pcap_pkthdr h;
 174                         pc->md.TotAccepted++;
 175                         h.ts = sp->ens_tstamp;
 176 #ifdef PCAP_FDDIPAD
 177                         h.len = sp->ens_count - pad;
 178 #else
 179                         h.len = sp->ens_count;
 180 #endif
 181                         h.caplen = buflen;
 182                         (*callback)(user, &h, p);
 183                         if (++n >= cnt && cnt > 0) {
 184                                 pc->cc = cc;
 185                                 pc->bp = bp;
 186                                 return (n);
 187                         }
 188                 }
 189         }
 190         pc->cc = 0;
 191         return (n);
 192 }
 193
 194 int
 195 pcap_stats(pcap_t *p, struct pcap_stat *ps)
 196 {
 197
 198         /*
 199          * If packet filtering is being done in the kernel:
 200          *
 201          *      "ps_recv" counts only packets that passed the filter.
 202          *      This does not include packets dropped because we
 203          *      ran out of buffer space.  (XXX - perhaps it should,
 204          *      by adding "ps_drop" to "ps_recv", for compatibility
 205          *      with some other platforms.  On the other hand, on
 206          *      some platforms "ps_recv" counts only packets that
 207          *      passed the filter, and on others it counts packets
 208          *      that didn't pass the filter....)
 209          *
 210          *      "ps_drop" counts packets that passed the kernel filter
 211          *      (if any) but were dropped because the input queue was
 212          *      full.
 213          *
 214          *      "ps_ifdrop" counts packets dropped by the network
 215          *      inteface (regardless of whether they would have passed
 216          *      the input filter, of course).
 217          *
 218          * If packet filtering is not being done in the kernel:
 219          *
 220          *      "ps_recv" counts only packets that passed the filter.
 221          *
 222          *      "ps_drop" counts packets that were dropped because the
 223          *      input queue was full, regardless of whether they passed
 224          *      the userland filter.
 225          *
 226          *      "ps_ifdrop" counts packets dropped by the network
 227          *      inteface (regardless of whether they would have passed
 228          *      the input filter, of course).
 229          *
 230          * These statistics don't include packets not yet read from
 231          * the kernel by libpcap, but they may include packets not
 232          * yet read from libpcap by the application.
 233          */
 234         ps->ps_recv = p->md.TotAccepted;
 235         ps->ps_drop = p->md.TotDrops;
 236         ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
 237         return (0);
 238 }
 239
 240 pcap_t *
 241 pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
 242 {
 243         pcap_t *p;
 244         short enmode;
 245         int backlog = -1;       /* request the most */
 246         struct enfilter Filter;
 247         struct endevp devparams;
 248
 249         p = (pcap_t *)malloc(sizeof(*p));
 250         if (p == NULL) {
 251                 snprintf(ebuf, PCAP_ERRBUF_SIZE,
 252                     "pcap_open_live: %s", pcap_strerror(errno));
 253                 return (0);
 254         }
 255         memset(p, 0, sizeof(*p));
 256         p->fd = pfopen(device, O_RDONLY);
 257         if (p->fd < 0) {
 258                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\
 259 your system may not be properly configured; see \"man packetfilter(4)\"\n",
 260                         device, pcap_strerror(errno));
 261                 goto bad;
 262         }
 263         p->md.OrigMissed = -1;
 264         enmode = ENTSTAMP|ENBATCH|ENNONEXCL;
 265         if (promisc)
 266                 enmode |= ENPROMISC;
 267         if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
 268                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
 269                     pcap_strerror(errno));
 270                 goto bad;
 271         }
 272 #ifdef  ENCOPYALL
 273         /* Try to set COPYALL mode so that we see packets to ourself */
 274         enmode = ENCOPYALL;
 275         (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
 276 #endif
 277         /* set the backlog */
 278         if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
 279                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
 280                     pcap_strerror(errno));
 281                 goto bad;
 282         }
 283         /* discover interface type */
 284         if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
 285                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
 286                     pcap_strerror(errno));
 287                 goto bad;
 288         }
 289         /* HACK: to compile prior to Ultrix 4.2 */
 290 #ifndef ENDT_FDDI
 291 #define ENDT_FDDI       4
 292 #endif
 293         switch (devparams.end_dev_type) {
 294
 295         case ENDT_10MB:
 296                 p->linktype = DLT_EN10MB;
 297                 p->offset = 2;
 298                 break;
 299
 300         case ENDT_FDDI:
 301                 p->linktype = DLT_FDDI;
 302                 break;
 303
 304 #ifdef ENDT_SLIP
 305         case ENDT_SLIP:
 306                 p->linktype = DLT_SLIP;
 307                 break;
 308 #endif
 309
 310 #ifdef ENDT_PPP
 311         case ENDT_PPP:
 312                 p->linktype = DLT_PPP;
 313                 break;
 314 #endif
 315
 316 #ifdef ENDT_LOOPBACK
 317         case ENDT_LOOPBACK:
 318                 /*
 319                  * It appears to use Ethernet framing, at least on
 320                  * Digital UNIX 4.0.
 321                  */
 322                 p->linktype = DLT_EN10MB;
 323                 p->offset = 2;
 324                 break;
 325 #endif
 326
 327 #ifdef ENDT_TRN
 328         case ENDT_TRN:
 329                 p->linktype = DLT_IEEE802;
 330                 break;
 331 #endif
 332
 333         default:
 334                 /*
 335                  * XXX - what about ENDT_IEEE802?  The pfilt.h header
 336                  * file calls this "IEEE 802 networks (non-Ethernet)",
 337                  * but that doesn't specify a specific link layer type;
 338                  * it could be 802.4, or 802.5 (except that 802.5 is
 339                  * ENDT_TRN), or 802.6, or 802.11, or....  That's why
 340                  * DLT_IEEE802 was hijacked to mean Token Ring in various
 341                  * BSDs, and why we went along with that hijacking.
 342                  *
 343                  * XXX - what about ENDT_HDLC and ENDT_NULL?
 344                  * Presumably, as ENDT_OTHER is just "Miscellaneous
 345                  * framing", there's not much we can do, as that
 346                  * doesn't specify a particular type of header.
 347                  */
 348                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "unknown data-link type %lu",
 349                     devparams.end_dev_type);
 350                 goto bad;
 351         }
 352         /* set truncation */
 353 #ifdef PCAP_FDDIPAD
 354         if (p->linktype == DLT_FDDI)
 355                 /* packetfilter includes the padding in the snapshot */
 356                 snaplen += pcap_fddipad;
 357 #endif
 358         if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) {
 359                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
 360                     pcap_strerror(errno));
 361                 goto bad;
 362         }
 363         p->snapshot = snaplen;
 364         /* accept all packets */
 365         memset(&Filter, 0, sizeof(Filter));
 366         Filter.enf_Priority = 37;       /* anything > 2 */
 367         Filter.enf_FilterLen = 0;       /* means "always true" */
 368         if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
 369                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
 370                     pcap_strerror(errno));
 371                 goto bad;
 372         }
 373
 374         if (to_ms != 0) {
 375                 struct timeval timeout;
 376                 timeout.tv_sec = to_ms / 1000;
 377                 timeout.tv_usec = (to_ms * 1000) % 1000000;
 378                 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 379                         snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
 380                                 pcap_strerror(errno));
 381                         goto bad;
 382                 }
 383         }
 384         p->bufsize = BUFSPACE;
 385         p->buffer = (u_char*)malloc(p->bufsize + p->offset);
 386
 387         return (p);
 388  bad:
 389         if (p->fd >= 0)
 390                 close(p->fd);
 391         free(p);
 392         return (NULL);
 393 }
 394
 395 int
 396 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
 397 {
 398         return (0);
 399 }
 400
 401 int
 402 pcap_setfilter(pcap_t *p, struct bpf_program *fp)
 403 {
 404         /*
 405          * See if BIOCSETF works.  If it does, the kernel supports
 406          * BPF-style filters, and we do not need to do post-filtering.
 407          */
 408         p->md.use_bpf = (ioctl(p->fd, BIOCSETF, (caddr_t)fp) >= 0);
 409         if (p->md.use_bpf) {
 410                 struct bpf_version bv;
 411
 412                 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) < 0) {
 413                         snprintf(p->errbuf, sizeof(p->errbuf),
 414                             "BIOCVERSION: %s", pcap_strerror(errno));
 415                         return (-1);
 416                 }
 417                 else if (bv.bv_major != BPF_MAJOR_VERSION ||
 418                          bv.bv_minor < BPF_MINOR_VERSION) {
 419                         fprintf(stderr,
 420                 "requires bpf language %d.%d or higher; kernel is %d.%d",
 421                                 BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
 422                               bv.bv_major, bv.bv_minor);
 423                         /* don't give up, just be inefficient */
 424                         p->md.use_bpf = 0;
 425                 }
 426         } else {
 427                 if (install_bpf_program(p, fp) < 0)
 428                         return (-1);
 429         }
 430
 431         /*XXX this goes in tcpdump*/
 432         if (p->md.use_bpf)
 433                 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
 434         else
 435                 fprintf(stderr, "tcpdump: Filtering in user process\n");
 436         return (0);
 437 }