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 1.62 2000-10-28 00:01:30 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         ps->ps_recv = p->md.TotAccepted;
 199         ps->ps_drop = p->md.TotDrops;
 200         ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
 201         return (0);
 202 }
 203
 204 pcap_t *
 205 pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
 206 {
 207         pcap_t *p;
 208         short enmode;
 209         int backlog = -1;       /* request the most */
 210         struct enfilter Filter;
 211         struct endevp devparams;
 212
 213         p = (pcap_t *)malloc(sizeof(*p));
 214         if (p == NULL) {
 215                 snprintf(ebuf, PCAP_ERRBUF_SIZE,
 216                     "pcap_open_live: %s", pcap_strerror(errno));
 217                 return (0);
 218         }
 219         memset(p, 0, sizeof(*p));
 220         p->fd = pfopen(device, O_RDONLY);
 221         if (p->fd < 0) {
 222                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\
 223 your system may not be properly configured; see \"man packetfilter(4)\"\n",
 224                         device, pcap_strerror(errno));
 225                 goto bad;
 226         }
 227         p->md.OrigMissed = -1;
 228         enmode = ENTSTAMP|ENBATCH|ENNONEXCL;
 229         if (promisc)
 230                 enmode |= ENPROMISC;
 231         if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
 232                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
 233                     pcap_strerror(errno));
 234                 goto bad;
 235         }
 236 #ifdef  ENCOPYALL
 237         /* Try to set COPYALL mode so that we see packets to ourself */
 238         enmode = ENCOPYALL;
 239         (void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
 240 #endif
 241         /* set the backlog */
 242         if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
 243                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
 244                     pcap_strerror(errno));
 245                 goto bad;
 246         }
 247         /* discover interface type */
 248         if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
 249                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
 250                     pcap_strerror(errno));
 251                 goto bad;
 252         }
 253         /* HACK: to compile prior to Ultrix 4.2 */
 254 #ifndef ENDT_FDDI
 255 #define ENDT_FDDI       4
 256 #endif
 257         switch (devparams.end_dev_type) {
 258
 259         case ENDT_10MB:
 260                 p->linktype = DLT_EN10MB;
 261                 p->offset = 2;
 262                 break;
 263
 264         case ENDT_FDDI:
 265                 p->linktype = DLT_FDDI;
 266                 break;
 267
 268         default:
 269                 /*
 270                  * XXX
 271                  * Currently, the Ultrix packet filter supports only
 272                  * Ethernet and FDDI.  Eventually, support for SLIP and PPP
 273                  * (and possibly others: T1?) should be added.
 274                  */
 275 #ifdef notdef
 276                 warning(
 277                    "Packet filter data-link type %d unknown, assuming Ethernet",
 278                     devparams.end_dev_type);
 279 #endif
 280                 p->linktype = DLT_EN10MB;
 281                 p->offset = 2;
 282                 break;
 283         }
 284         /* set truncation */
 285 #ifdef PCAP_FDDIPAD
 286         if (p->linktype == DLT_FDDI)
 287                 /* packetfilter includes the padding in the snapshot */
 288                 snaplen += pcap_fddipad;
 289 #endif
 290         if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) {
 291                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
 292                     pcap_strerror(errno));
 293                 goto bad;
 294         }
 295         p->snapshot = snaplen;
 296         /* accept all packets */
 297         memset(&Filter, 0, sizeof(Filter));
 298         Filter.enf_Priority = 37;       /* anything > 2 */
 299         Filter.enf_FilterLen = 0;       /* means "always true" */
 300         if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
 301                 snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
 302                     pcap_strerror(errno));
 303                 goto bad;
 304         }
 305
 306         if (to_ms != 0) {
 307                 struct timeval timeout;
 308                 timeout.tv_sec = to_ms / 1000;
 309                 timeout.tv_usec = (to_ms * 1000) % 1000000;
 310                 if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
 311                         snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
 312                                 pcap_strerror(errno));
 313                         goto bad;
 314                 }
 315         }
 316         p->bufsize = BUFSPACE;
 317         p->buffer = (u_char*)malloc(p->bufsize + p->offset);
 318
 319         return (p);
 320  bad:
 321         free(p);
 322         return (NULL);
 323 }
 324
 325 int
 326 pcap_setfilter(pcap_t *p, struct bpf_program *fp)
 327 {
 328         /*
 329          * See if BIOCSETF works.  If it does, the kernel supports
 330          * BPF-style filters, and we do not need to do post-filtering.
 331          */
 332         p->md.use_bpf = (ioctl(p->fd, BIOCSETF, (caddr_t)fp) >= 0);
 333         if (p->md.use_bpf) {
 334                 struct bpf_version bv;
 335
 336                 if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) < 0) {
 337                         snprintf(p->errbuf, sizeof(p->errbuf),
 338                             "BIOCVERSION: %s", pcap_strerror(errno));
 339                         return (-1);
 340                 }
 341                 else if (bv.bv_major != BPF_MAJOR_VERSION ||
 342                          bv.bv_minor < BPF_MINOR_VERSION) {
 343                         fprintf(stderr,
 344                 "requires bpf language %d.%d or higher; kernel is %d.%d",
 345                                 BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
 346                               bv.bv_major, bv.bv_minor);
 347                         /* don't give up, just be inefficient */
 348                         p->md.use_bpf = 0;
 349                 }
 350         } else {
 351                 if (install_bpf_program(p, fp) < 0)
 352                         return (-1);
 353         }
 354
 355         /*XXX this goes in tcpdump*/
 356         if (p->md.use_bpf)
 357                 fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
 358         else
 359                 fprintf(stderr, "tcpdump: Filtering in user process\n");
 360         return (0);
 361 }