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 1.54 1999-10-07 23:46:40 mcr Exp $ (LBL)";
  28 #endif
  29
  30 #include <sys/types.h>
  31 #include <sys/time.h>
  32 #include <sys/timeb.h>
  33 #include <sys/socket.h>
  34 #include <sys/file.h>
  35 #include <sys/ioctl.h>
  36 #include <net/pfilt.h>
  37
  38 #if __STDC__
  39 struct mbuf;
  40 struct rtentry;
  41 #endif
  42
  43 #include <net/if.h>
  44
  45 #include <netinet/in.h>
  46 #include <netinet/in_systm.h>
  47 #include <netinet/ip.h>
  48 #include <netinet/if_ether.h>
  49 #include <netinet/ip_var.h>
  50 #include <netinet/udp.h>
  51 #include <netinet/udp_var.h>
  52 #include <netinet/tcp.h>
  53 #include <netinet/tcpip.h>
  54
  55 #include <ctype.h>
  56 #include <errno.h>
  57 #include <netdb.h>
  58 #include <stdio.h>
  59 #include <stdlib.h>
  60 #include <string.h>
  61 #include <unistd.h>
  62
  63 #include "pcap-int.h"
  64
  65 #include "gnuc.h"
  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                         sprintf(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                         sprintf(pc->errbuf, "pf short read (%d)", cc);
 131                         return (-1);
 132                 }
 133 #ifdef LBL_ALIGN
 134                 if ((long)bp & 3) {
 135                         sp = &stamp;
 136                         memcpy((char *)sp, (char *)bp, sizeof(*sp));
 137                 } else
 138 #endif
 139                         sp = (struct enstamp *)bp;
 140                 if (sp->ens_stamplen != sizeof(*sp)) {
 141                         sprintf(pc->errbuf, "pf short stamplen (%d)",
 142                             sp->ens_stamplen);
 143                         return (-1);
 144                 }
 145
 146                 p = bp + sp->ens_stamplen;
 147                 buflen = sp->ens_count;
 148                 if (buflen > pc->snapshot)
 149                         buflen = pc->snapshot;
 150
 151                 /* Calculate inc before possible pad update */
 152                 inc = ENALIGN(buflen + sp->ens_stamplen);
 153                 cc -= inc;
 154                 bp += inc;
 155 #ifdef PCAP_FDDIPAD
 156                 p += pad;
 157                 buflen -= pad;
 158 #endif
 159                 pc->md.TotPkts++;
 160                 pc->md.TotDrops += sp->ens_dropped;
 161                 pc->md.TotMissed = sp->ens_ifoverflows;
 162                 if (pc->md.OrigMissed < 0)
 163                         pc->md.OrigMissed = pc->md.TotMissed;
 164
 165                 /*
 166                  * Short-circuit evaluation: if using BPF filter
 167                  * in kernel, no need to do it now.
 168                  */
 169                 if (fcode == NULL ||
 170                     bpf_filter(fcode, p, sp->ens_count, buflen)) {
 171                         struct pcap_pkthdr h;
 172                         pc->md.TotAccepted++;
 173                         h.ts = sp->ens_tstamp;
 174 #ifdef PCAP_FDDIPAD
 175                         h.len = sp->ens_count - pad;
 176 #else
 177                         h.len = sp->ens_count;
 178 #endif
 179                         h.caplen = buflen;
 180                         (*callback)(user, &h, p);
 181                         if (++n >= cnt && cnt > 0) {
 182                                 pc->cc = cc;
 183                                 pc->bp = bp;
 184                                 return (n);
 185                         }
 186                 }
 187         }
 188         pc->cc = 0;
 189         return (n);
 190 }
 191
 192 int
 193 pcap_stats(pcap_t *p, struct pcap_stat *ps)
 194 {
 195
 196         ps->ps_recv = p->md.TotAccepted;
 197         ps->ps_drop = p->md.TotDrops;
 198         ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
 199         return (0);
 200 }
 201
 202 pcap_t *
 203 pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
 204 {
 205         pcap_t *p;
 206         short enmode;
 207         int backlog = -1;       /* request the most */
 208         struct enfilter Filter;
 209         struct endevp devparams;
 210
 211         p = (pcap_t *)malloc(sizeof(*p));
 212         if (p == NULL) {
 213                 sprintf(ebuf, "pcap_open_live: %s", pcap_strerror(errno));
 214                 return (0);
 215         }
 216         bzero((char *)p, sizeof(*p));
 217         p->fd = pfopen(device, O_RDONLY);
 218         if (p->fd < 0) {
 219                 sprintf(ebuf, "pf open: %s: %s\n\
 220 your system may not be properly configured; see \"man packetfilter(4)\"\n",
 221                         device, pcap_strerror(errno));
 222                 goto bad;
 223         }
 224         p->md.OrigMissed = -1;
 225         enmode = ENTSTAMP|ENBATCH|ENNONEXCL;
 226         if (promisc)
 227                 enmode |= ENPROMISC;
 228         if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
 229                 sprintf(ebuf, "EIOCMBIS: %s", pcap_strerror(errno));
 230                 goto bad;
 231         }
 232 #ifdef  ENCOPYALL
 233         /* Try to set COPYALL mode so that we see packets to ourself */
 234         enmode = ENCOPYALL;
 235         (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
 236 #endif
 237         /* set the backlog */
 238         if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
 239                 sprintf(ebuf, "EIOCSETW: %s", pcap_strerror(errno));
 240                 goto bad;
 241         }
 242         /* discover interface type */
 243         if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
 244                 sprintf(ebuf, "EIOCDEVP: %s", pcap_strerror(errno));
 245                 goto bad;
 246         }
 247         /* HACK: to compile prior to Ultrix 4.2 */
 248 #ifndef ENDT_FDDI
 249 #define ENDT_FDDI       4
 250 #endif
 251         switch (devparams.end_dev_type) {
 252
 253         case ENDT_10MB:
 254                 p->linktype = DLT_EN10MB;
 255                 p->offset = 2;
 256                 break;
 257
 258         case ENDT_FDDI:
 259                 p->linktype = DLT_FDDI;
 260                 break;
 261
 262         default:
 263                 /*
 264                  * XXX
 265                  * Currently, the Ultrix packet filter supports only
 266                  * Ethernet and FDDI.  Eventually, support for SLIP and PPP
 267                  * (and possibly others: T1?) should be added.
 268                  */
 269 #ifdef notdef
 270                 warning(
 271                    "Packet filter data-link type %d unknown, assuming Ethernet",
 272                     devparams.end_dev_type);
 273 #endif
 274                 p->linktype = DLT_EN10MB;
 275                 p->offset = 2;
 276                 break;
 277         }
 278         /* set truncation */
 279 #ifdef PCAP_FDDIPAD
 280         if (p->linktype == DLT_FDDI)
 281                 /* packetfilter includes the padding in the snapshot */
 282                 snaplen += pcap_fddipad;
 283 #endif
 284         if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) {
 285                 sprintf(ebuf, "EIOCTRUNCATE: %s", pcap_strerror(errno));
 286                 goto bad;
 287         }
 288         p->snapshot = snaplen;
 289         /* accept all packets */
 290         bzero((char *)&Filter, sizeof(Filter));
 291         Filter.enf_Priority = 37;       /* anything > 2 */
 292         Filter.enf_FilterLen = 0;       /* means "always true" */
 293         if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
 294                 sprintf(ebuf, "EIOCSETF: %s", pcap_strerror(errno));
 295                 goto bad;
 296         }
 297
 298         if (to_ms != 0) {
 299                 struct timeval timeout;
 300                 timeout.tv_sec = to_ms / 1000;
 301                 timeout.tv_usec = (to_ms * 1000) % 1000000;
 302                 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 303                         sprintf(ebuf, "EIOCSRTIMEOUT: %s",
 304                                 pcap_strerror(errno));
 305                         goto bad;
 306                 }
 307         }
 308         p->bufsize = BUFSPACE;
 309         p->buffer = (u_char*)malloc(p->bufsize + p->offset);
 310
 311         return (p);
 312  bad:
 313         free(p);
 314         return (NULL);
 315 }
 316
 317 int
 318 pcap_setfilter(pcap_t *p, struct bpf_program *fp)
 319 {
 320         /*
 321          * See if BIOCSETF works.  If it does, the kernel supports
 322          * BPF-style filters, and we do not need to do post-filtering.
 323          */
 324         p->md.use_bpf = (ioctl(p->fd, BIOCSETF, (caddr_t)fp) >= 0);
 325         if (p->md.use_bpf) {
 326                 struct bpf_version bv;
 327
 328                 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) < 0) {
 329                         sprintf(p->errbuf, "BIOCVERSION: %s",
 330                                 pcap_strerror(errno));
 331                         return (-1);
 332                 }
 333                 else if (bv.bv_major != BPF_MAJOR_VERSION ||
 334                          bv.bv_minor < BPF_MINOR_VERSION) {
 335                         fprintf(stderr,
 336                 "requires bpf language %d.%d or higher; kernel is %d.%d",
 337                                 BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
 338                               bv.bv_major, bv.bv_minor);
 339                         /* don't give up, just be inefficient */
 340                         p->md.use_bpf = 0;
 341                 }
 342         } else
 343                 p->fcode = *fp;
 344
 345         /*XXX this goes in tcpdump*/
 346         if (p->md.use_bpf)
 347                 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
 348         else
 349                 fprintf(stderr, "tcpdump: Filtering in user process\n");
 350         return (0);
 351 }