2 * Copyright (c) 1993, 1994, 1995, 1996, 1998
3 * The Regents of the University of California. All rights reserved.
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
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.
22 static const char rcsid[] _U_ =
23 "@(#) $Header: /tcpdump/master/libpcap/pcap-bpf.c,v 1.86.2.9 2006/01/22 05:28:34 guy Exp $ (LBL)";
30 #include <sys/param.h> /* optionally get BSD define */
32 #include <sys/timeb.h>
33 #include <sys/socket.h>
35 #include <sys/ioctl.h>
36 #include <sys/utsname.h>
43 * Make "pcap.h" not include "pcap-bpf.h"; we are going to include the
44 * native OS version, as we need "struct bpf_config" from it.
46 #define PCAP_DONT_INCLUDE_PCAP_BPF_H
48 #include <sys/types.h>
51 * Prevent bpf.h from redefining the DLT_ values to their
52 * IFT_ values, as we're going to return the standard libpcap
53 * values, not IBM's non-standard IFT_ values.
59 #include <net/if_types.h> /* for IFT_ values */
60 #include <sys/sysconfig.h>
61 #include <sys/device.h>
62 #include <sys/cfgodm.h>
66 #define domakedev makedev64
67 #define getmajor major64
68 #define bpf_hdr bpf_hdr32
70 #define domakedev makedev
71 #define getmajor major
72 #endif /* __64BIT__ */
74 #define BPF_NAME "bpf"
76 #define DRIVER_PATH "/usr/lib/drivers"
77 #define BPF_NODE "/dev/bpf"
78 static int bpfloadedflag = 0;
79 static int odmlockid = 0;
99 #endif /* HAVE_DAG_API */
101 #ifdef HAVE_OS_PROTO_H
102 #include "os-proto.h"
105 #include "gencode.h" /* for "no_optimize" */
107 static int pcap_setfilter_bpf(pcap_t *p, struct bpf_program *fp);
108 static int pcap_setdirection_bpf(pcap_t *, pcap_direction_t);
109 static int pcap_set_datalink_bpf(pcap_t *p, int dlt);
112 pcap_stats_bpf(pcap_t *p, struct pcap_stat *ps)
117 * "ps_recv" counts packets handed to the filter, not packets
118 * that passed the filter. This includes packets later dropped
119 * because we ran out of buffer space.
121 * "ps_drop" counts packets dropped inside the BPF device
122 * because we ran out of buffer space. It doesn't count
123 * packets dropped by the interface driver. It counts
124 * only packets that passed the filter.
126 * Both statistics include packets not yet read from the kernel
127 * by libpcap, and thus not yet seen by the application.
129 if (ioctl(p->fd, BIOCGSTATS, (caddr_t)&s) < 0) {
130 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCGSTATS: %s",
131 pcap_strerror(errno));
135 ps->ps_recv = s.bs_recv;
136 ps->ps_drop = s.bs_drop;
141 pcap_read_bpf(pcap_t *p, int cnt, pcap_handler callback, u_char *user)
145 register u_char *bp, *ep;
147 struct bpf_insn *fcode;
152 fcode = p->md.use_bpf ? NULL : p->fcode.bf_insns;
155 * Has "pcap_breakloop()" been called?
159 * Yes - clear the flag that indicates that it
160 * has, and return -2 to indicate that we were
161 * told to break out of the loop.
168 cc = read(p->fd, (char *)p->buffer, p->bufsize);
170 /* Don't choke when we get ptraced */
179 * Sigh. More AIX wonderfulness.
181 * For some unknown reason the uiomove()
182 * operation in the bpf kernel extension
183 * used to copy the buffer into user
184 * space sometimes returns EFAULT. I have
185 * no idea why this is the case given that
186 * a kernel debugger shows the user buffer
187 * is correct. This problem appears to
188 * be mostly mitigated by the memset of
189 * the buffer before it is first used.
190 * Very strange.... Shaun Clowes
192 * In any case this means that we shouldn't
193 * treat EFAULT as a fatal error; as we
194 * don't have an API for returning
195 * a "some packets were dropped since
196 * the last packet you saw" indication,
197 * we just ignore EFAULT and keep reading.
204 #if defined(sun) && !defined(BSD)
206 * Due to a SunOS bug, after 2^31 bytes, the kernel
207 * file offset overflows and read fails with EINVAL.
208 * The lseek() to 0 will fix things.
211 if (lseek(p->fd, 0L, SEEK_CUR) +
213 (void)lseek(p->fd, 0L, SEEK_SET);
219 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "read: %s",
220 pcap_strerror(errno));
228 * Loop through each packet.
230 #define bhp ((struct bpf_hdr *)bp)
236 register int caplen, hdrlen;
239 * Has "pcap_breakloop()" been called?
240 * If so, return immediately - if we haven't read any
241 * packets, clear the flag and return -2 to indicate
242 * that we were told to break out of the loop, otherwise
243 * leave the flag set, so that the *next* call will break
244 * out of the loop without having read any packets, and
245 * return the number of packets we've processed so far.
258 caplen = bhp->bh_caplen;
259 hdrlen = bhp->bh_hdrlen;
262 * Short-circuit evaluation: if using BPF filter
263 * in kernel, no need to do it now.
266 * Note: the filter code was generated assuming
267 * that p->fddipad was the amount of padding
268 * before the header, as that's what's required
269 * in the kernel, so we run the filter before
270 * skipping that padding.
274 bpf_filter(fcode, datap, bhp->bh_datalen, caplen)) {
275 struct pcap_pkthdr pkthdr;
277 pkthdr.ts.tv_sec = bhp->bh_tstamp.tv_sec;
280 * AIX's BPF returns seconds/nanoseconds time
281 * stamps, not seconds/microseconds time stamps.
283 pkthdr.ts.tv_usec = bhp->bh_tstamp.tv_usec/1000;
285 pkthdr.ts.tv_usec = bhp->bh_tstamp.tv_usec;
289 pkthdr.caplen = caplen - pad;
292 if (bhp->bh_datalen > pad)
293 pkthdr.len = bhp->bh_datalen - pad;
298 pkthdr.caplen = caplen;
299 pkthdr.len = bhp->bh_datalen;
301 (*callback)(user, &pkthdr, datap);
302 bp += BPF_WORDALIGN(caplen + hdrlen);
303 if (++n >= cnt && cnt > 0) {
312 bp += BPF_WORDALIGN(caplen + hdrlen);
321 pcap_inject_bpf(pcap_t *p, const void *buf, size_t size)
325 ret = write(p->fd, buf, size);
327 if (ret == -1 && errno == EAFNOSUPPORT) {
329 * In Mac OS X, there's a bug wherein setting the
330 * BIOCSHDRCMPLT flag causes writes to fail; see,
333 * http://cerberus.sourcefire.com/~jeff/archives/patches/macosx/BIOCSHDRCMPLT-10.3.3.patch
335 * So, if, on OS X, we get EAFNOSUPPORT from the write, we
336 * assume it's due to that bug, and turn off that flag
337 * and try again. If we succeed, it either means that
338 * somebody applied the fix from that URL, or other patches
341 * http://cerberus.sourcefire.com/~jeff/archives/patches/macosx/
343 * and are running a Darwin kernel with those fixes, or
344 * that Apple fixed the problem in some OS X release.
346 u_int spoof_eth_src = 0;
348 if (ioctl(p->fd, BIOCSHDRCMPLT, &spoof_eth_src) == -1) {
349 (void)snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
350 "send: can't turn off BIOCSHDRCMPLT: %s",
351 pcap_strerror(errno));
356 * Now try the write again.
358 ret = write(p->fd, buf, size);
360 #endif /* __APPLE__ */
362 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
363 pcap_strerror(errno));
371 bpf_odminit(char *errbuf)
375 if (odm_initialize() == -1) {
376 if (odm_err_msg(odmerrno, &errstr) == -1)
377 errstr = "Unknown error";
378 snprintf(errbuf, PCAP_ERRBUF_SIZE,
379 "bpf_load: odm_initialize failed: %s",
384 if ((odmlockid = odm_lock("/etc/objrepos/config_lock", ODM_WAIT)) == -1) {
385 if (odm_err_msg(odmerrno, &errstr) == -1)
386 errstr = "Unknown error";
387 snprintf(errbuf, PCAP_ERRBUF_SIZE,
388 "bpf_load: odm_lock of /etc/objrepos/config_lock failed: %s",
397 bpf_odmcleanup(char *errbuf)
401 if (odm_unlock(odmlockid) == -1) {
402 if (odm_err_msg(odmerrno, &errstr) == -1)
403 errstr = "Unknown error";
404 snprintf(errbuf, PCAP_ERRBUF_SIZE,
405 "bpf_load: odm_unlock failed: %s",
410 if (odm_terminate() == -1) {
411 if (odm_err_msg(odmerrno, &errstr) == -1)
412 errstr = "Unknown error";
413 snprintf(errbuf, PCAP_ERRBUF_SIZE,
414 "bpf_load: odm_terminate failed: %s",
423 bpf_load(char *errbuf)
427 int numminors, i, rc;
430 struct bpf_config cfg_bpf;
431 struct cfg_load cfg_ld;
432 struct cfg_kmod cfg_km;
435 * This is very very close to what happens in the real implementation
436 * but I've fixed some (unlikely) bug situations.
441 if (bpf_odminit(errbuf) != 0)
444 major = genmajor(BPF_NAME);
446 snprintf(errbuf, PCAP_ERRBUF_SIZE,
447 "bpf_load: genmajor failed: %s", pcap_strerror(errno));
451 minors = getminor(major, &numminors, BPF_NAME);
453 minors = genminor("bpf", major, 0, BPF_MINORS, 1, 1);
455 snprintf(errbuf, PCAP_ERRBUF_SIZE,
456 "bpf_load: genminor failed: %s",
457 pcap_strerror(errno));
462 if (bpf_odmcleanup(errbuf))
465 rc = stat(BPF_NODE "0", &sbuf);
466 if (rc == -1 && errno != ENOENT) {
467 snprintf(errbuf, PCAP_ERRBUF_SIZE,
468 "bpf_load: can't stat %s: %s",
469 BPF_NODE "0", pcap_strerror(errno));
473 if (rc == -1 || getmajor(sbuf.st_rdev) != major) {
474 for (i = 0; i < BPF_MINORS; i++) {
475 sprintf(buf, "%s%d", BPF_NODE, i);
477 if (mknod(buf, S_IRUSR | S_IFCHR, domakedev(major, i)) == -1) {
478 snprintf(errbuf, PCAP_ERRBUF_SIZE,
479 "bpf_load: can't mknod %s: %s",
480 buf, pcap_strerror(errno));
486 /* Check if the driver is loaded */
487 memset(&cfg_ld, 0x0, sizeof(cfg_ld));
489 sprintf(cfg_ld.path, "%s/%s", DRIVER_PATH, BPF_NAME);
490 if ((sysconfig(SYS_QUERYLOAD, (void *)&cfg_ld, sizeof(cfg_ld)) == -1) ||
491 (cfg_ld.kmid == 0)) {
492 /* Driver isn't loaded, load it now */
493 if (sysconfig(SYS_SINGLELOAD, (void *)&cfg_ld, sizeof(cfg_ld)) == -1) {
494 snprintf(errbuf, PCAP_ERRBUF_SIZE,
495 "bpf_load: could not load driver: %s",
501 /* Configure the driver */
502 cfg_km.cmd = CFG_INIT;
503 cfg_km.kmid = cfg_ld.kmid;
504 cfg_km.mdilen = sizeof(cfg_bpf);
505 cfg_km.mdiptr = (void *)&cfg_bpf;
506 for (i = 0; i < BPF_MINORS; i++) {
507 cfg_bpf.devno = domakedev(major, i);
508 if (sysconfig(SYS_CFGKMOD, (void *)&cfg_km, sizeof(cfg_km)) == -1) {
509 snprintf(errbuf, PCAP_ERRBUF_SIZE,
510 "bpf_load: could not configure driver: %s",
523 bpf_open(pcap_t *p, char *errbuf)
527 char device[sizeof "/dev/bpf0000000000"];
531 * Load the bpf driver, if it isn't already loaded,
532 * and create the BPF device entries, if they don't
535 if (bpf_load(errbuf) == -1)
540 * Go through all the minors and find one that isn't in use.
543 (void)snprintf(device, sizeof(device), "/dev/bpf%d", n++);
545 * Initially try a read/write open (to allow the inject
546 * method to work). If that fails due to permission
547 * issues, fall back to read-only. This allows a
548 * non-root user to be granted specific access to pcap
549 * capabilities via file permissions.
551 * XXX - we should have an API that has a flag that
552 * controls whether to open read-only or read-write,
553 * so that denial of permission to send (or inability
554 * to send, if sending packets isn't supported on
555 * the device in question) can be indicated at open
558 fd = open(device, O_RDWR);
559 if (fd == -1 && errno == EACCES)
560 fd = open(device, O_RDONLY);
561 } while (fd < 0 && errno == EBUSY);
564 * XXX better message for all minors used
567 snprintf(errbuf, PCAP_ERRBUF_SIZE, "(no devices found) %s: %s",
568 device, pcap_strerror(errno));
574 * We include the OS's <net/bpf.h>, not our "pcap-bpf.h", so we probably
575 * don't get DLT_DOCSIS defined.
578 #define DLT_DOCSIS 143
582 pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
587 struct bpf_version bv;
589 struct bpf_dltlist bdl;
591 #if defined(BIOCGHDRCMPLT) && defined(BIOCSHDRCMPLT)
592 u_int spoof_eth_src = 1;
596 struct bpf_insn total_insn;
597 struct bpf_program total_prog;
598 struct utsname osinfo;
601 if (strstr(device, "dag")) {
602 return dag_open_live(device, snaplen, promisc, to_ms, ebuf);
604 #endif /* HAVE_DAG_API */
607 memset(&bdl, 0, sizeof(bdl));
610 p = (pcap_t *)malloc(sizeof(*p));
612 snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
613 pcap_strerror(errno));
616 memset(p, 0, sizeof(*p));
617 fd = bpf_open(p, ebuf);
622 p->snapshot = snaplen;
624 if (ioctl(fd, BIOCVERSION, (caddr_t)&bv) < 0) {
625 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCVERSION: %s",
626 pcap_strerror(errno));
629 if (bv.bv_major != BPF_MAJOR_VERSION ||
630 bv.bv_minor < BPF_MINOR_VERSION) {
631 snprintf(ebuf, PCAP_ERRBUF_SIZE,
632 "kernel bpf filter out of date");
637 * Try finding a good size for the buffer; 32768 may be too
638 * big, so keep cutting it in half until we find a size
639 * that works, or run out of sizes to try. If the default
640 * is larger, don't make it smaller.
642 * XXX - there should be a user-accessible hook to set the
643 * initial buffer size.
645 if ((ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) || v < 32768)
647 for ( ; v != 0; v >>= 1) {
648 /* Ignore the return value - this is because the call fails
649 * on BPF systems that don't have kernel malloc. And if
650 * the call fails, it's no big deal, we just continue to
651 * use the standard buffer size.
653 (void) ioctl(fd, BIOCSBLEN, (caddr_t)&v);
655 (void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
656 if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) >= 0)
657 break; /* that size worked; we're done */
659 if (errno != ENOBUFS) {
660 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETIF: %s: %s",
661 device, pcap_strerror(errno));
667 snprintf(ebuf, PCAP_ERRBUF_SIZE,
668 "BIOCSBLEN: %s: No buffer size worked", device);
672 /* Get the data link layer type. */
673 if (ioctl(fd, BIOCGDLT, (caddr_t)&v) < 0) {
674 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGDLT: %s",
675 pcap_strerror(errno));
680 * AIX's BPF returns IFF_ types, not DLT_ types, in BIOCGDLT.
703 * We don't know what to map this to yet.
705 snprintf(ebuf, PCAP_ERRBUF_SIZE, "unknown interface type %u",
710 #if _BSDI_VERSION - 0 >= 199510
711 /* The SLIP and PPP link layer header changed in BSD/OS 2.1 */
726 case 12: /*DLT_C_HDLC*/
733 p->fddipad = PCAP_FDDIPAD;
741 * We know the default link type -- now determine all the DLTs
742 * this interface supports. If this fails with EINVAL, it's
743 * not fatal; we just don't get to use the feature later.
745 if (ioctl(fd, BIOCGDLTLIST, (caddr_t)&bdl) == 0) {
749 bdl.bfl_list = (u_int *) malloc(sizeof(u_int) * (bdl.bfl_len + 1));
750 if (bdl.bfl_list == NULL) {
751 (void)snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
752 pcap_strerror(errno));
756 if (ioctl(fd, BIOCGDLTLIST, (caddr_t)&bdl) < 0) {
757 (void)snprintf(ebuf, PCAP_ERRBUF_SIZE,
758 "BIOCGDLTLIST: %s", pcap_strerror(errno));
764 * OK, for real Ethernet devices, add DLT_DOCSIS to the
765 * list, so that an application can let you choose it,
766 * in case you're capturing DOCSIS traffic that a Cisco
767 * Cable Modem Termination System is putting out onto
768 * an Ethernet (it doesn't put an Ethernet header onto
769 * the wire, it puts raw DOCSIS frames out on the wire
770 * inside the low-level Ethernet framing).
772 * A "real Ethernet device" is defined here as a device
773 * that has a link-layer type of DLT_EN10MB and that has
774 * no alternate link-layer types; that's done to exclude
775 * 802.11 interfaces (which might or might not be the
776 * right thing to do, but I suspect it is - Ethernet <->
777 * 802.11 bridges would probably badly mishandle frames
778 * that don't have Ethernet headers).
780 if (p->linktype == DLT_EN10MB) {
782 for (i = 0; i < bdl.bfl_len; i++) {
783 if (bdl.bfl_list[i] != DLT_EN10MB) {
790 * We reserved one more slot at the end of
793 bdl.bfl_list[bdl.bfl_len] = DLT_DOCSIS;
797 p->dlt_count = bdl.bfl_len;
798 p->dlt_list = bdl.bfl_list;
800 if (errno != EINVAL) {
801 (void)snprintf(ebuf, PCAP_ERRBUF_SIZE,
802 "BIOCGDLTLIST: %s", pcap_strerror(errno));
809 * If this is an Ethernet device, and we don't have a DLT_ list,
810 * give it a list with DLT_EN10MB and DLT_DOCSIS. (That'd give
811 * 802.11 interfaces DLT_DOCSIS, which isn't the right thing to
812 * do, but there's not much we can do about that without finding
813 * some other way of determining whether it's an Ethernet or 802.11
816 if (p->linktype == DLT_EN10MB && p->dlt_count == 0) {
817 p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
819 * If that fails, just leave the list empty.
821 if (p->dlt_list != NULL) {
822 p->dlt_list[0] = DLT_EN10MB;
823 p->dlt_list[1] = DLT_DOCSIS;
828 #if defined(BIOCGHDRCMPLT) && defined(BIOCSHDRCMPLT)
830 * Do a BIOCSHDRCMPLT, if defined, to turn that flag on, so
831 * the link-layer source address isn't forcibly overwritten.
832 * (Should we ignore errors? Should we do this only if
833 * we're open for writing?)
835 * XXX - I seem to remember some packet-sending bug in some
836 * BSDs - check CVS log for "bpf.c"?
838 if (ioctl(fd, BIOCSHDRCMPLT, &spoof_eth_src) == -1) {
839 (void)snprintf(ebuf, PCAP_ERRBUF_SIZE,
840 "BIOCSHDRCMPLT: %s", pcap_strerror(errno));
847 * XXX - is this seconds/nanoseconds in AIX?
848 * (Treating it as such doesn't fix the timeout
849 * problem described below.)
852 to.tv_sec = to_ms / 1000;
853 to.tv_usec = (to_ms * 1000) % 1000000;
854 if (ioctl(p->fd, BIOCSRTIMEOUT, (caddr_t)&to) < 0) {
855 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSRTIMEOUT: %s",
856 pcap_strerror(errno));
864 * Darren Reed notes that
866 * On AIX (4.2 at least), if BIOCIMMEDIATE is not set, the
867 * timeout appears to be ignored and it waits until the buffer
868 * is filled before returning. The result of not having it
869 * set is almost worse than useless if your BPF filter
870 * is reducing things to only a few packets (i.e. one every
873 * so we turn BIOCIMMEDIATE mode on if this is AIX.
875 * We don't turn it on for other platforms, as that means we
876 * get woken up for every packet, which may not be what we want;
877 * in the Winter 1993 USENIX paper on BPF, they say:
879 * Since a process might want to look at every packet on a
880 * network and the time between packets can be only a few
881 * microseconds, it is not possible to do a read system call
882 * per packet and BPF must collect the data from several
883 * packets and return it as a unit when the monitoring
884 * application does a read.
886 * which I infer is the reason for the timeout - it means we
887 * wait that amount of time, in the hopes that more packets
888 * will arrive and we'll get them all with one read.
890 * Setting BIOCIMMEDIATE mode on FreeBSD (and probably other
891 * BSDs) causes the timeout to be ignored.
893 * On the other hand, some platforms (e.g., Linux) don't support
894 * timeouts, they just hand stuff to you as soon as it arrives;
895 * if that doesn't cause a problem on those platforms, it may
896 * be OK to have BIOCIMMEDIATE mode on BSD as well.
898 * (Note, though, that applications may depend on the read
899 * completing, even if no packets have arrived, when the timeout
900 * expires, e.g. GUI applications that have to check for input
901 * while waiting for packets to arrive; a non-zero timeout
902 * prevents "select()" from working right on FreeBSD and
903 * possibly other BSDs, as the timer doesn't start until a
904 * "read()" is done, so the timer isn't in effect if the
905 * application is blocked on a "select()", and the "select()"
906 * doesn't get woken up for a BPF device until the buffer
910 if (ioctl(p->fd, BIOCIMMEDIATE, &v) < 0) {
911 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCIMMEDIATE: %s",
912 pcap_strerror(errno));
915 #endif /* BIOCIMMEDIATE */
919 /* set promiscuous mode, okay if it fails */
920 if (ioctl(p->fd, BIOCPROMISC, NULL) < 0) {
921 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCPROMISC: %s",
922 pcap_strerror(errno));
926 if (ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) {
927 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCGBLEN: %s",
928 pcap_strerror(errno));
932 p->buffer = (u_char *)malloc(p->bufsize);
933 if (p->buffer == NULL) {
934 snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
935 pcap_strerror(errno));
939 /* For some strange reason this seems to prevent the EFAULT
940 * problems we have experienced from AIX BPF. */
941 memset(p->buffer, 0x0, p->bufsize);
945 * If there's no filter program installed, there's
946 * no indication to the kernel of what the snapshot
947 * length should be, so no snapshotting is done.
949 * Therefore, when we open the device, we install
950 * an "accept everything" filter with the specified
953 total_insn.code = (u_short)(BPF_RET | BPF_K);
956 total_insn.k = snaplen;
958 total_prog.bf_len = 1;
959 total_prog.bf_insns = &total_insn;
960 if (ioctl(p->fd, BIOCSETF, (caddr_t)&total_prog) < 0) {
961 snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s",
962 pcap_strerror(errno));
967 * On most BPF platforms, either you can do a "select()" or
968 * "poll()" on a BPF file descriptor and it works correctly,
969 * or you can do it and it will return "readable" if the
970 * hold buffer is full but not if the timeout expires *and*
971 * a non-blocking read will, if the hold buffer is empty
972 * but the store buffer isn't empty, rotate the buffers
973 * and return what packets are available.
975 * In the latter case, the fact that a non-blocking read
976 * will give you the available packets means you can work
977 * around the failure of "select()" and "poll()" to wake up
978 * and return "readable" when the timeout expires by using
979 * the timeout as the "select()" or "poll()" timeout, putting
980 * the BPF descriptor into non-blocking mode, and read from
981 * it regardless of whether "select()" reports it as readable
984 * However, in FreeBSD 4.3 and 4.4, "select()" and "poll()"
985 * won't wake up and return "readable" if the timer expires
986 * and non-blocking reads return EWOULDBLOCK if the hold
987 * buffer is empty, even if the store buffer is non-empty.
989 * This means the workaround in question won't work.
991 * Therefore, on FreeBSD 4.3 and 4.4, we set "p->selectable_fd"
992 * to -1, which means "sorry, you can't use 'select()' or 'poll()'
993 * here". On all other BPF platforms, we set it to the FD for
994 * the BPF device; in NetBSD, OpenBSD, and Darwin, a non-blocking
995 * read will, if the hold buffer is empty and the store buffer
996 * isn't empty, rotate the buffers and return what packets are
997 * there (and in sufficiently recent versions of OpenBSD
998 * "select()" and "poll()" should work correctly).
1000 * XXX - what about AIX?
1002 p->selectable_fd = p->fd; /* assume select() works until we know otherwise */
1003 if (uname(&osinfo) == 0) {
1005 * We can check what OS this is.
1007 if (strcmp(osinfo.sysname, "FreeBSD") == 0) {
1008 if (strncmp(osinfo.release, "4.3-", 4) == 0 ||
1009 strncmp(osinfo.release, "4.4-", 4) == 0)
1010 p->selectable_fd = -1;
1014 p->read_op = pcap_read_bpf;
1015 p->inject_op = pcap_inject_bpf;
1016 p->setfilter_op = pcap_setfilter_bpf;
1017 p->setdirection_op = pcap_setdirection_bpf;
1018 p->set_datalink_op = pcap_set_datalink_bpf;
1019 p->getnonblock_op = pcap_getnonblock_fd;
1020 p->setnonblock_op = pcap_setnonblock_fd;
1021 p->stats_op = pcap_stats_bpf;
1022 p->close_op = pcap_close_common;
1027 if (p->dlt_list != NULL)
1034 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
1037 if (dag_platform_finddevs(alldevsp, errbuf) < 0)
1039 #endif /* HAVE_DAG_API */
1045 pcap_setfilter_bpf(pcap_t *p, struct bpf_program *fp)
1048 * It looks that BPF code generated by gen_protochain() is not
1049 * compatible with some of kernel BPF code (for example BSD/OS 3.1).
1050 * Take a safer side for now.
1054 * XXX - what if we already have a filter in the kernel?
1056 if (install_bpf_program(p, fp) < 0)
1058 p->md.use_bpf = 0; /* filtering in userland */
1063 * Free any user-mode filter we might happen to have installed.
1065 pcap_freecode(&p->fcode);
1068 * Try to install the kernel filter.
1070 if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
1071 snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCSETF: %s",
1072 pcap_strerror(errno));
1075 p->md.use_bpf = 1; /* filtering in the kernel */
1078 * Discard any previously-received packets, as they might have
1079 * passed whatever filter was formerly in effect, but might
1080 * not pass this filter (BIOCSETF discards packets buffered
1081 * in the kernel, so you can lose packets in any case).
1088 * Set direction flag: Which packets do we accept on a forwarding
1089 * single device? IN, OUT or both?
1092 pcap_setdirection_bpf(pcap_t *p, pcap_direction_t d)
1099 * We don't support PCAP_D_OUT.
1101 if (d == PCAP_D_OUT) {
1102 snprintf(p->errbuf, sizeof(p->errbuf),
1103 "Setting direction to PCAP_D_OUT is not supported on BPF");
1107 seesent = (d == PCAP_D_INOUT);
1108 if (ioctl(p->fd, BIOCSSEESENT, &seesent) == -1) {
1109 (void) snprintf(p->errbuf, sizeof(p->errbuf),
1110 "Cannot set direction to %s: %s",
1111 (d == PCAP_D_INOUT) ? "PCAP_D_INOUT" : "PCAP_D_IN",
1117 (void) snprintf(p->errbuf, sizeof(p->errbuf),
1118 "This system doesn't support BIOCSSEESENT, so the direction can't be set");
1124 pcap_set_datalink_bpf(pcap_t *p, int dlt)
1127 if (ioctl(p->fd, BIOCSDLT, &dlt) == -1) {
1128 (void) snprintf(p->errbuf, sizeof(p->errbuf),
1129 "Cannot set DLT %d: %s", dlt, strerror(errno));