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 1.57 2000-07-01 03:35:08 assar 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 struct mbuf;
  39 struct rtentry;
  40 #include <net/if.h>
  41
  42 #include <netinet/in.h>
  43 #include <netinet/in_systm.h>
  44 #include <netinet/ip.h>
  45 #include <netinet/if_ether.h>
  46 #include <netinet/ip_var.h>
  47 #include <netinet/udp.h>
  48 #include <netinet/udp_var.h>
  49 #include <netinet/tcp.h>
  50 #include <netinet/tcpip.h>
  51
  52 #include <ctype.h>
  53 #include <errno.h>
  54 #include <netdb.h>
  55 #include <stdio.h>
  56 #include <stdlib.h>
  57 #include <string.h>
  58 #include <unistd.h>
  59
  60 #include "pcap-int.h"
  61
  62 #include "gnuc.h"
  63 #ifdef HAVE_OS_PROTO_H
  64 #include "os-proto.h"
  65 #endif
  66
  67 /*
  68  * BUFSPACE is the size in bytes of the packet read buffer.  Most tcpdump
  69  * applications aren't going to need more than 200 bytes of packet header
  70  * and the read shouldn't return more packets than packetfilter's internal
  71  * queue limit (bounded at 256).
  72  */
  73 #define BUFSPACE (200 * 256)
  74
  75 int
  76 pcap_read(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
  77 {
  78         register u_char *p, *bp;
  79         struct bpf_insn *fcode;
  80         register int cc, n, buflen, inc;
  81         register struct enstamp *sp;
  82 #ifdef LBL_ALIGN
  83         struct enstamp stamp;
  84 #endif
  85 #ifdef PCAP_FDDIPAD
  86         register int pad;
  87 #endif
  88
  89         fcode = pc->md.use_bpf ? NULL : pc->fcode.bf_insns;
  90  again:
  91         cc = pc->cc;
  92         if (cc == 0) {
  93                 cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
  94                 if (cc < 0) {
  95                         if (errno == EWOULDBLOCK)
  96                                 return (0);
  97                         if (errno == EINVAL &&
  98                             lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
  99                                 /*
 100                                  * Due to a kernel bug, after 2^31 bytes,
 101                                  * the kernel file offset overflows and
 102                                  * read fails with EINVAL. The lseek()
 103                                  * to 0 will fix things.
 104                                  */
 105                                 (void)lseek(pc->fd, 0L, SEEK_SET);
 106                                 goto again;
 107                         }
 108                         snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
 109                                 pcap_strerror(errno));
 110                         return (-1);
 111                 }
 112                 bp = pc->buffer + pc->offset;
 113         } else
 114                 bp = pc->bp;
 115         /*
 116          * Loop through each packet.
 117          */
 118         n = 0;
 119 #ifdef PCAP_FDDIPAD
 120         if (pc->linktype == DLT_FDDI)
 121                 pad = pcap_fddipad;
 122         else
 123                 pad = 0;
 124 #endif
 125         while (cc > 0) {
 126                 if (cc < sizeof(*sp)) {
 127                         snprintf(pc->errbuf, sizeof(pc->errbuf),
 128                             "pf short read (%d)", cc);
 129                         return (-1);
 130                 }
 131 #ifdef LBL_ALIGN
 132                 if ((long)bp & 3) {
 133                         sp = &stamp;
 134                         memcpy((char *)sp, (char *)bp, sizeof(*sp));
 135                 } else
 136 #endif
 137                         sp = (struct enstamp *)bp;
 138                 if (sp->ens_stamplen != sizeof(*sp)) {
 139                         snprintf(pc->errbuf, sizeof(pc->errbuf),
 140                             "pf short stamplen (%d)",
 141                             sp->ens_stamplen);
 142                         return (-1);
 143                 }
 144
 145                 p = bp + sp->ens_stamplen;
 146                 buflen = sp->ens_count;
 147                 if (buflen > pc->snapshot)
 148                         buflen = pc->snapshot;
 149
 150                 /* Calculate inc before possible pad update */
 151                 inc = ENALIGN(buflen + sp->ens_stamplen);
 152                 cc -= inc;
 153                 bp += inc;
 154 #ifdef PCAP_FDDIPAD
 155                 p += pad;
 156                 buflen -= pad;
 157 #endif
 158                 pc->md.TotPkts++;
 159                 pc->md.TotDrops += sp->ens_dropped;
 160                 pc->md.TotMissed = sp->ens_ifoverflows;
 161                 if (pc->md.OrigMissed < 0)
 162                         pc->md.OrigMissed = pc->md.TotMissed;
 163
 164                 /*
 165                  * Short-circuit evaluation: if using BPF filter
 166                  * in kernel, no need to do it now.
 167                  */
 168                 if (fcode == NULL ||
 169                     bpf_filter(fcode, p, sp->ens_count, buflen)) {
 170                         struct pcap_pkthdr h;
 171                         pc->md.TotAccepted++;
 172                         h.ts = sp->ens_tstamp;
 173 #ifdef PCAP_FDDIPAD
 174                         h.len = sp->ens_count - pad;
 175 #else
 176                         h.len = sp->ens_count;
 177 #endif
 178                         h.caplen = buflen;
 179                         (*callback)(user, &h, p);
 180                         if (++n >= cnt && cnt > 0) {
 181                                 pc->cc = cc;
 182                                 pc->bp = bp;
 183                                 return (n);
 184                         }
 185                 }
 186         }
 187         pc->cc = 0;
 188         return (n);
 189 }
 190
 191 int
 192 pcap_stats(pcap_t *p, struct pcap_stat *ps)
 193 {
 194
 195         ps->ps_recv = p->md.TotAccepted;
 196         ps->ps_drop = p->md.TotDrops;
 197         ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
 198         return (0);
 199 }
 200
 201 pcap_t *
 202 pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
 203 {
 204         pcap_t *p;
 205         short enmode;
 206         int backlog = -1;       /* request the most */
 207         struct enfilter Filter;
 208         struct endevp devparams;
 209
 210         p = (pcap_t *)malloc(sizeof(*p));
 211         if (p == NULL) {
 212                 snprintf(ebuf, PCAP_ERRBUF_SIZE,
 213                     "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                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "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                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
 230                     pcap_strerror(errno));
 231                 goto bad;
 232         }
 233 #ifdef  ENCOPYALL
 234         /* Try to set COPYALL mode so that we see packets to ourself */
 235         enmode = ENCOPYALL;
 236         (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
 237 #endif
 238         /* set the backlog */
 239         if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
 240                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
 241                     pcap_strerror(errno));
 242                 goto bad;
 243         }
 244         /* discover interface type */
 245         if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
 246                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
 247                     pcap_strerror(errno));
 248                 goto bad;
 249         }
 250         /* HACK: to compile prior to Ultrix 4.2 */
 251 #ifndef ENDT_FDDI
 252 #define ENDT_FDDI       4
 253 #endif
 254         switch (devparams.end_dev_type) {
 255
 256         case ENDT_10MB:
 257                 p->linktype = DLT_EN10MB;
 258                 p->offset = 2;
 259                 break;
 260
 261         case ENDT_FDDI:
 262                 p->linktype = DLT_FDDI;
 263                 break;
 264
 265         default:
 266                 /*
 267                  * XXX
 268                  * Currently, the Ultrix packet filter supports only
 269                  * Ethernet and FDDI.  Eventually, support for SLIP and PPP
 270                  * (and possibly others: T1?) should be added.
 271                  */
 272 #ifdef notdef
 273                 warning(
 274                    "Packet filter data-link type %d unknown, assuming Ethernet",
 275                     devparams.end_dev_type);
 276 #endif
 277                 p->linktype = DLT_EN10MB;
 278                 p->offset = 2;
 279                 break;
 280         }
 281         /* set truncation */
 282 #ifdef PCAP_FDDIPAD
 283         if (p->linktype == DLT_FDDI)
 284                 /* packetfilter includes the padding in the snapshot */
 285                 snaplen += pcap_fddipad;
 286 #endif
 287         if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) {
 288                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
 289                     pcap_strerror(errno));
 290                 goto bad;
 291         }
 292         p->snapshot = snaplen;
 293         /* accept all packets */
 294         bzero((char *)&Filter, sizeof(Filter));
 295         Filter.enf_Priority = 37;       /* anything > 2 */
 296         Filter.enf_FilterLen = 0;       /* means "always true" */
 297         if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
 298                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
 299                     pcap_strerror(errno));
 300                 goto bad;
 301         }
 302
 303         if (to_ms != 0) {
 304                 struct timeval timeout;
 305                 timeout.tv_sec = to_ms / 1000;
 306                 timeout.tv_usec = (to_ms * 1000) % 1000000;
 307                 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 308                         snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
 309                                 pcap_strerror(errno));
 310                         goto bad;
 311                 }
 312         }
 313         p->bufsize = BUFSPACE;
 314         p->buffer = (u_char*)malloc(p->bufsize + p->offset);
 315
 316         return (p);
 317  bad:
 318         free(p);
 319         return (NULL);
 320 }
 321
 322 int
 323 pcap_setfilter(pcap_t *p, struct bpf_program *fp)
 324 {
 325         /*
 326          * See if BIOCSETF works.  If it does, the kernel supports
 327          * BPF-style filters, and we do not need to do post-filtering.
 328          */
 329         p->md.use_bpf = (ioctl(p->fd, BIOCSETF, (caddr_t)fp) >= 0);
 330         if (p->md.use_bpf) {
 331                 struct bpf_version bv;
 332
 333                 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) < 0) {
 334                         snprintf(p->errbuf, sizeof(p->errbuf),
 335                             "BIOCVERSION: %s", pcap_strerror(errno));
 336                         return (-1);
 337                 }
 338                 else if (bv.bv_major != BPF_MAJOR_VERSION ||
 339                          bv.bv_minor < BPF_MINOR_VERSION) {
 340                         fprintf(stderr,
 341                 "requires bpf language %d.%d or higher; kernel is %d.%d",
 342                                 BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
 343                               bv.bv_major, bv.bv_minor);
 344                         /* don't give up, just be inefficient */
 345                         p->md.use_bpf = 0;
 346                 }
 347         } else
 348                 p->fcode = *fp;
 349
 350         /*XXX this goes in tcpdump*/
 351         if (p->md.use_bpf)
 352                 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
 353         else
 354                 fprintf(stderr, "tcpdump: Filtering in user process\n");
 355         return (0);
 356 }