2 * pcap-linux.c: Packet capture interface to the Linux kernel
4 * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org>
5 * Sebastian Krahmer <krahmer@cs.uni-potsdam.de>
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
19 * 3. The names of the authors may not be used to endorse or promote
20 * products derived from this software without specific prior
23 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
25 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
27 * Modifications: Added PACKET_MMAP support
28 * Paolo Abeni <paolo.abeni@email.it>
30 * based on previous works of:
31 * Simon Patarin <patarin@cs.unibo.it>
32 * Phil Wood <cpw@lanl.gov>
34 * Monitor-mode support for mac80211 includes code taken from the iw
35 * command; the copyright notice for that code is
37 * Copyright (c) 2007, 2008 Johannes Berg
38 * Copyright (c) 2007 Andy Lutomirski
39 * Copyright (c) 2007 Mike Kershaw
40 * Copyright (c) 2008 Gábor Stefanik
42 * All rights reserved.
44 * Redistribution and use in source and binary forms, with or without
45 * modification, are permitted provided that the following conditions
47 * 1. Redistributions of source code must retain the above copyright
48 * notice, this list of conditions and the following disclaimer.
49 * 2. Redistributions in binary form must reproduce the above copyright
50 * notice, this list of conditions and the following disclaimer in the
51 * documentation and/or other materials provided with the distribution.
52 * 3. The name of the author may not be used to endorse or promote products
53 * derived from this software without specific prior written permission.
55 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
56 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
57 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
58 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
59 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
60 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
61 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
62 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
63 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
69 static const char rcsid[] _U_ =
70 "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.164 2008-12-14 22:00:57 guy Exp $ (LBL)";
74 * Known problems with 2.0[.x] kernels:
76 * - The loopback device gives every packet twice; on 2.2[.x] kernels,
77 * if we use PF_PACKET, we can filter out the transmitted version
78 * of the packet by using data in the "sockaddr_ll" returned by
79 * "recvfrom()", but, on 2.0[.x] kernels, we have to use
80 * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
81 * "sockaddr_pkt" which doesn't give us enough information to let
84 * - We have to set the interface's IFF_PROMISC flag ourselves, if
85 * we're to run in promiscuous mode, which means we have to turn
86 * it off ourselves when we're done; the kernel doesn't keep track
87 * of how many sockets are listening promiscuously, which means
88 * it won't get turned off automatically when no sockets are
89 * listening promiscuously. We catch "pcap_close()" and, for
90 * interfaces we put into promiscuous mode, take them out of
91 * promiscuous mode - which isn't necessarily the right thing to
92 * do, if another socket also requested promiscuous mode between
93 * the time when we opened the socket and the time when we close
96 * - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
97 * return the amount of data that you could have read, rather than
98 * the amount that was returned, so we can't just allocate a buffer
99 * whose size is the snapshot length and pass the snapshot length
100 * as the byte count, and also pass MSG_TRUNC, so that the return
101 * value tells us how long the packet was on the wire.
103 * This means that, if we want to get the actual size of the packet,
104 * so we can return it in the "len" field of the packet header,
105 * we have to read the entire packet, not just the part that fits
106 * within the snapshot length, and thus waste CPU time copying data
107 * from the kernel that our caller won't see.
109 * We have to get the actual size, and supply it in "len", because
110 * otherwise, the IP dissector in tcpdump, for example, will complain
111 * about "truncated-ip", as the packet will appear to have been
112 * shorter, on the wire, than the IP header said it should have been.
130 #include <sys/socket.h>
131 #include <sys/ioctl.h>
132 #include <sys/utsname.h>
133 #include <sys/mman.h>
134 #include <linux/if.h>
135 #include <netinet/in.h>
136 #include <linux/if_ether.h>
137 #include <net/if_arp.h>
141 #include "pcap-int.h"
142 #include "pcap/sll.h"
143 #include "pcap/vlan.h"
146 #include "pcap-dag.h"
147 #endif /* HAVE_DAG_API */
149 #ifdef HAVE_SEPTEL_API
150 #include "pcap-septel.h"
151 #endif /* HAVE_SEPTEL_API */
154 #include "pcap-snf.h"
155 #endif /* HAVE_SNF_API */
157 #ifdef PCAP_SUPPORT_USB
158 #include "pcap-usb-linux.h"
161 #ifdef PCAP_SUPPORT_BT
162 #include "pcap-bt-linux.h"
165 #ifdef PCAP_SUPPORT_CAN
166 #include "pcap-can-linux.h"
169 #if PCAP_SUPPORT_CANUSB
170 #include "pcap-canusb-linux.h"
173 #ifdef PCAP_SUPPORT_NETFILTER
174 #include "pcap-netfilter-linux.h"
178 * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
179 * sockets rather than SOCK_PACKET sockets.
181 * To use them, we include <linux/if_packet.h> rather than
182 * <netpacket/packet.h>; we do so because
184 * some Linux distributions (e.g., Slackware 4.0) have 2.2 or
185 * later kernels and libc5, and don't provide a <netpacket/packet.h>
188 * not all versions of glibc2 have a <netpacket/packet.h> file
189 * that defines stuff needed for some of the 2.4-or-later-kernel
190 * features, so if the system has a 2.4 or later kernel, we
191 * still can't use those features.
193 * We're already including a number of other <linux/XXX.h> headers, and
194 * this code is Linux-specific (no other OS has PF_PACKET sockets as
195 * a raw packet capture mechanism), so it's not as if you gain any
196 * useful portability by using <netpacket/packet.h>
198 * XXX - should we just include <linux/if_packet.h> even if PF_PACKET
199 * isn't defined? It only defines one data structure in 2.0.x, so
200 * it shouldn't cause any problems.
203 # include <linux/if_packet.h>
206 * On at least some Linux distributions (for example, Red Hat 5.2),
207 * there's no <netpacket/packet.h> file, but PF_PACKET is defined if
208 * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
209 * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
210 * the PACKET_xxx stuff.
212 * So we check whether PACKET_HOST is defined, and assume that we have
213 * PF_PACKET sockets only if it is defined.
216 # define HAVE_PF_PACKET_SOCKETS
217 # ifdef PACKET_AUXDATA
218 # define HAVE_PACKET_AUXDATA
219 # endif /* PACKET_AUXDATA */
220 # endif /* PACKET_HOST */
223 /* check for memory mapped access avaibility. We assume every needed
224 * struct is defined if the macro TPACKET_HDRLEN is defined, because it
225 * uses many ring related structs and macros */
226 # ifdef TPACKET_HDRLEN
227 # define HAVE_PACKET_RING
228 # ifdef TPACKET2_HDRLEN
229 # define HAVE_TPACKET2
231 # define TPACKET_V1 0
232 # endif /* TPACKET2_HDRLEN */
233 # endif /* TPACKET_HDRLEN */
234 #endif /* PF_PACKET */
236 #ifdef SO_ATTACH_FILTER
237 #include <linux/types.h>
238 #include <linux/filter.h>
242 * We need linux/sockios.h if we have linux/net_tstamp.h (for time stamp
243 * specification) or linux/ethtool.h (for ethtool ioctls to get offloading
246 #if defined(HAVE_LINUX_NET_TSTAMP_H) || defined(HAVE_LINUX_ETHTOOL_H)
247 #include <linux/sockios.h>
250 #ifdef HAVE_LINUX_NET_TSTAMP_H
251 #include <linux/net_tstamp.h>
255 * Got Wireless Extensions?
257 #ifdef HAVE_LINUX_WIRELESS_H
258 #include <linux/wireless.h>
259 #endif /* HAVE_LINUX_WIRELESS_H */
265 #include <linux/nl80211.h>
267 #include <netlink/genl/genl.h>
268 #include <netlink/genl/family.h>
269 #include <netlink/genl/ctrl.h>
270 #include <netlink/msg.h>
271 #include <netlink/attr.h>
272 #endif /* HAVE_LIBNL */
275 * Got ethtool support?
277 #ifdef HAVE_LINUX_ETHTOOL_H
278 #include <linux/ethtool.h>
281 #ifndef HAVE_SOCKLEN_T
282 typedef int socklen_t;
287 * This is being compiled on a system that lacks MSG_TRUNC; define it
288 * with the value it has in the 2.2 and later kernels, so that, on
289 * those kernels, when we pass it in the flags argument to "recvfrom()"
290 * we're passing the right value and thus get the MSG_TRUNC behavior
291 * we want. (We don't get that behavior on 2.0[.x] kernels, because
292 * they didn't support MSG_TRUNC.)
294 #define MSG_TRUNC 0x20
299 * This is being compiled on a system that lacks SOL_PACKET; define it
300 * with the value it has in the 2.2 and later kernels, so that we can
301 * set promiscuous mode in the good modern way rather than the old
302 * 2.0-kernel crappy way.
304 #define SOL_PACKET 263
307 #define MAX_LINKHEADER_SIZE 256
310 * When capturing on all interfaces we use this as the buffer size.
311 * Should be bigger then all MTUs that occur in real life.
312 * 64kB should be enough for now.
314 #define BIGGER_THAN_ALL_MTUS (64*1024)
317 * Prototypes for internal functions and methods.
319 static void map_arphrd_to_dlt(pcap_t *, int, int);
320 #ifdef HAVE_PF_PACKET_SOCKETS
321 static short int map_packet_type_to_sll_type(short int);
323 static int pcap_activate_linux(pcap_t *);
324 static int activate_old(pcap_t *);
325 static int activate_new(pcap_t *);
326 static int activate_mmap(pcap_t *, int *);
327 static int pcap_can_set_rfmon_linux(pcap_t *);
328 static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *);
329 static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
330 static int pcap_inject_linux(pcap_t *, const void *, size_t);
331 static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
332 static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
333 static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
334 static void pcap_cleanup_linux(pcap_t *);
337 struct tpacket_hdr *h1;
338 struct tpacket2_hdr *h2;
342 #ifdef HAVE_PACKET_RING
343 #define RING_GET_FRAME(h) (((union thdr **)h->buffer)[h->offset])
345 static void destroy_ring(pcap_t *handle);
346 static int create_ring(pcap_t *handle, int *status);
347 static int prepare_tpacket_socket(pcap_t *handle);
348 static void pcap_cleanup_linux_mmap(pcap_t *);
349 static int pcap_read_linux_mmap(pcap_t *, int, pcap_handler , u_char *);
350 static int pcap_setfilter_linux_mmap(pcap_t *, struct bpf_program *);
351 static int pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf);
352 static int pcap_getnonblock_mmap(pcap_t *p, char *errbuf);
353 static void pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h,
354 const u_char *bytes);
358 * Wrap some ioctl calls
360 #ifdef HAVE_PF_PACKET_SOCKETS
361 static int iface_get_id(int fd, const char *device, char *ebuf);
362 #endif /* HAVE_PF_PACKET_SOCKETS */
363 static int iface_get_mtu(int fd, const char *device, char *ebuf);
364 static int iface_get_arptype(int fd, const char *device, char *ebuf);
365 #ifdef HAVE_PF_PACKET_SOCKETS
366 static int iface_bind(int fd, int ifindex, char *ebuf);
367 #ifdef IW_MODE_MONITOR
368 static int has_wext(int sock_fd, const char *device, char *ebuf);
369 #endif /* IW_MODE_MONITOR */
370 static int enter_rfmon_mode(pcap_t *handle, int sock_fd,
372 #endif /* HAVE_PF_PACKET_SOCKETS */
373 static int iface_get_offload(pcap_t *handle);
374 static int iface_bind_old(int fd, const char *device, char *ebuf);
376 #ifdef SO_ATTACH_FILTER
377 static int fix_program(pcap_t *handle, struct sock_fprog *fcode,
379 static int fix_offset(struct bpf_insn *p);
380 static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
381 static int reset_kernel_filter(pcap_t *handle);
383 static struct sock_filter total_insn
384 = BPF_STMT(BPF_RET | BPF_K, 0);
385 static struct sock_fprog total_fcode
386 = { 1, &total_insn };
387 #endif /* SO_ATTACH_FILTER */
390 pcap_create(const char *device, char *ebuf)
395 * A null device name is equivalent to the "any" device.
401 if (strstr(device, "dag")) {
402 return dag_create(device, ebuf);
404 #endif /* HAVE_DAG_API */
406 #ifdef HAVE_SEPTEL_API
407 if (strstr(device, "septel")) {
408 return septel_create(device, ebuf);
410 #endif /* HAVE_SEPTEL_API */
413 handle = snf_create(device, ebuf);
414 if (strstr(device, "snf") || handle != NULL)
417 #endif /* HAVE_SNF_API */
419 #ifdef PCAP_SUPPORT_BT
420 if (strstr(device, "bluetooth")) {
421 return bt_create(device, ebuf);
425 #if PCAP_SUPPORT_CANUSB
426 if (strstr(device, "canusb")) {
427 return canusb_create(device, ebuf);
431 #ifdef PCAP_SUPPORT_CAN
432 if ((strncmp(device, "can", 3) == 0 && isdigit(device[3])) ||
433 (strncmp(device, "vcan", 4) == 0 && isdigit(device[4]))) {
434 return can_create(device, ebuf);
438 #ifdef PCAP_SUPPORT_USB
439 if (strstr(device, "usbmon")) {
440 return usb_create(device, ebuf);
444 #ifdef PCAP_SUPPORT_NETFILTER
445 if (strncmp(device, "nflog", strlen("nflog")) == 0) {
446 return nflog_create(device, ebuf);
450 handle = pcap_create_common(device, ebuf);
454 handle->activate_op = pcap_activate_linux;
455 handle->can_set_rfmon_op = pcap_can_set_rfmon_linux;
456 #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
458 * We claim that we support:
460 * software time stamps, with no details about their precision;
461 * hardware time stamps, synced to the host time;
462 * hardware time stamps, not synced to the host time.
464 * XXX - we can't ask a device whether it supports
465 * hardware time stamps, so we just claim all devices do.
467 handle->tstamp_type_count = 3;
468 handle->tstamp_type_list = malloc(3 * sizeof(u_int));
469 if (handle->tstamp_type_list == NULL) {
473 handle->tstamp_type_list[0] = PCAP_TSTAMP_HOST;
474 handle->tstamp_type_list[1] = PCAP_TSTAMP_ADAPTER;
475 handle->tstamp_type_list[2] = PCAP_TSTAMP_ADAPTER_UNSYNCED;
483 * If interface {if} is a mac80211 driver, the file
484 * /sys/class/net/{if}/phy80211 is a symlink to
485 * /sys/class/ieee80211/{phydev}, for some {phydev}.
487 * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at
488 * least, has a "wmaster0" device and a "wlan0" device; the
489 * latter is the one with the IP address. Both show up in
490 * "tcpdump -D" output. Capturing on the wmaster0 device
491 * captures with 802.11 headers.
493 * airmon-ng searches through /sys/class/net for devices named
494 * monN, starting with mon0; as soon as one *doesn't* exist,
495 * it chooses that as the monitor device name. If the "iw"
496 * command exists, it does "iw dev {if} interface add {monif}
497 * type monitor", where {monif} is the monitor device. It
498 * then (sigh) sleeps .1 second, and then configures the
499 * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface
500 * is a file, it writes {mondev}, without a newline, to that file,
501 * and again (sigh) sleeps .1 second, and then iwconfig's that
502 * device into monitor mode and configures it up. Otherwise,
503 * you can't do monitor mode.
505 * All these devices are "glued" together by having the
506 * /sys/class/net/{device}/phy80211 links pointing to the same
507 * place, so, given a wmaster, wlan, or mon device, you can
508 * find the other devices by looking for devices with
509 * the same phy80211 link.
511 * To turn monitor mode off, delete the monitor interface,
512 * either with "iw dev {monif} interface del" or by sending
513 * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface
515 * Note: if you try to create a monitor device named "monN", and
516 * there's already a "monN" device, it fails, as least with
517 * the netlink interface (which is what iw uses), with a return
518 * value of -ENFILE. (Return values are negative errnos.) We
519 * could probably use that to find an unused device.
521 * Yes, you can have multiple monitor devices for a given
526 * Is this a mac80211 device? If so, fill in the physical device path and
527 * return 1; if not, return 0. On an error, fill in handle->errbuf and
531 get_mac80211_phydev(pcap_t *handle, const char *device, char *phydev_path,
532 size_t phydev_max_pathlen)
538 * Generate the path string for the symlink to the physical device.
540 if (asprintf(&pathstr, "/sys/class/net/%s/phy80211", device) == -1) {
541 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
542 "%s: Can't generate path name string for /sys/class/net device",
546 bytes_read = readlink(pathstr, phydev_path, phydev_max_pathlen);
547 if (bytes_read == -1) {
548 if (errno == ENOENT || errno == EINVAL) {
550 * Doesn't exist, or not a symlink; assume that
551 * means it's not a mac80211 device.
556 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
557 "%s: Can't readlink %s: %s", device, pathstr,
563 phydev_path[bytes_read] = '\0';
567 #ifdef HAVE_LIBNL_2_x
568 #define get_nl_errmsg nl_geterror
570 /* libnl 2.x compatibility code */
572 #define nl_sock nl_handle
574 static inline struct nl_handle *
575 nl_socket_alloc(void)
577 return nl_handle_alloc();
581 nl_socket_free(struct nl_handle *h)
583 nl_handle_destroy(h);
586 #define get_nl_errmsg strerror
589 __genl_ctrl_alloc_cache(struct nl_handle *h, struct nl_cache **cache)
591 struct nl_cache *tmp = genl_ctrl_alloc_cache(h);
597 #define genl_ctrl_alloc_cache __genl_ctrl_alloc_cache
598 #endif /* !HAVE_LIBNL_2_x */
600 struct nl80211_state {
601 struct nl_sock *nl_sock;
602 struct nl_cache *nl_cache;
603 struct genl_family *nl80211;
607 nl80211_init(pcap_t *handle, struct nl80211_state *state, const char *device)
611 state->nl_sock = nl_socket_alloc();
612 if (!state->nl_sock) {
613 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
614 "%s: failed to allocate netlink handle", device);
618 if (genl_connect(state->nl_sock)) {
619 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
620 "%s: failed to connect to generic netlink", device);
621 goto out_handle_destroy;
624 err = genl_ctrl_alloc_cache(state->nl_sock, &state->nl_cache);
626 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
627 "%s: failed to allocate generic netlink cache: %s",
628 device, get_nl_errmsg(-err));
629 goto out_handle_destroy;
632 state->nl80211 = genl_ctrl_search_by_name(state->nl_cache, "nl80211");
633 if (!state->nl80211) {
634 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
635 "%s: nl80211 not found", device);
642 nl_cache_free(state->nl_cache);
644 nl_socket_free(state->nl_sock);
649 nl80211_cleanup(struct nl80211_state *state)
651 genl_family_put(state->nl80211);
652 nl_cache_free(state->nl_cache);
653 nl_socket_free(state->nl_sock);
657 add_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
658 const char *device, const char *mondevice)
664 ifindex = iface_get_id(sock_fd, device, handle->errbuf);
670 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
671 "%s: failed to allocate netlink msg", device);
675 genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
676 0, NL80211_CMD_NEW_INTERFACE, 0);
677 NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
678 NLA_PUT_STRING(msg, NL80211_ATTR_IFNAME, mondevice);
679 NLA_PUT_U32(msg, NL80211_ATTR_IFTYPE, NL80211_IFTYPE_MONITOR);
681 err = nl_send_auto_complete(state->nl_sock, msg);
683 #ifdef HAVE_LIBNL_2_x
684 if (err == -NLE_FAILURE) {
686 if (err == -ENFILE) {
689 * Device not available; our caller should just
690 * keep trying. (libnl 2.x maps ENFILE to
691 * NLE_FAILURE; it can also map other errors
692 * to that, but there's not much we can do
699 * Real failure, not just "that device is not
702 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
703 "%s: nl_send_auto_complete failed adding %s interface: %s",
704 device, mondevice, get_nl_errmsg(-err));
709 err = nl_wait_for_ack(state->nl_sock);
711 #ifdef HAVE_LIBNL_2_x
712 if (err == -NLE_FAILURE) {
714 if (err == -ENFILE) {
717 * Device not available; our caller should just
718 * keep trying. (libnl 2.x maps ENFILE to
719 * NLE_FAILURE; it can also map other errors
720 * to that, but there's not much we can do
727 * Real failure, not just "that device is not
730 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
731 "%s: nl_wait_for_ack failed adding %s interface: %s",
732 device, mondevice, get_nl_errmsg(-err));
745 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
746 "%s: nl_put failed adding %s interface",
753 del_mon_if(pcap_t *handle, int sock_fd, struct nl80211_state *state,
754 const char *device, const char *mondevice)
760 ifindex = iface_get_id(sock_fd, mondevice, handle->errbuf);
766 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
767 "%s: failed to allocate netlink msg", device);
771 genlmsg_put(msg, 0, 0, genl_family_get_id(state->nl80211), 0,
772 0, NL80211_CMD_DEL_INTERFACE, 0);
773 NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, ifindex);
775 err = nl_send_auto_complete(state->nl_sock, msg);
777 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
778 "%s: nl_send_auto_complete failed deleting %s interface: %s",
779 device, mondevice, get_nl_errmsg(-err));
783 err = nl_wait_for_ack(state->nl_sock);
785 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
786 "%s: nl_wait_for_ack failed adding %s interface: %s",
787 device, mondevice, get_nl_errmsg(-err));
799 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
800 "%s: nl_put failed deleting %s interface",
807 enter_rfmon_mode_mac80211(pcap_t *handle, int sock_fd, const char *device)
810 char phydev_path[PATH_MAX+1];
811 struct nl80211_state nlstate;
816 * Is this a mac80211 device?
818 ret = get_mac80211_phydev(handle, device, phydev_path, PATH_MAX);
820 return ret; /* error */
822 return 0; /* no error, but not mac80211 device */
825 * XXX - is this already a monN device?
827 * Is that determined by old Wireless Extensions ioctls?
831 * OK, it's apparently a mac80211 device.
832 * Try to find an unused monN device for it.
834 ret = nl80211_init(handle, &nlstate, device);
837 for (n = 0; n < UINT_MAX; n++) {
841 char mondevice[3+10+1]; /* mon{UINT_MAX}\0 */
843 snprintf(mondevice, sizeof mondevice, "mon%u", n);
844 ret = add_mon_if(handle, sock_fd, &nlstate, device, mondevice);
846 handle->md.mondevice = strdup(mondevice);
851 * Hard failure. Just return ret; handle->errbuf
852 * has already been set.
854 nl80211_cleanup(&nlstate);
859 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
860 "%s: No free monN interfaces", device);
861 nl80211_cleanup(&nlstate);
868 * Sleep for .1 seconds.
871 delay.tv_nsec = 500000000;
872 nanosleep(&delay, NULL);
876 * If we haven't already done so, arrange to have
877 * "pcap_close_all()" called when we exit.
879 if (!pcap_do_addexit(handle)) {
881 * "atexit()" failed; don't put the interface
882 * in rfmon mode, just give up.
884 return PCAP_ERROR_RFMON_NOTSUP;
888 * Now configure the monitor interface up.
890 memset(&ifr, 0, sizeof(ifr));
891 strncpy(ifr.ifr_name, handle->md.mondevice, sizeof(ifr.ifr_name));
892 if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
893 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
894 "%s: Can't get flags for %s: %s", device,
895 handle->md.mondevice, strerror(errno));
896 del_mon_if(handle, sock_fd, &nlstate, device,
897 handle->md.mondevice);
898 nl80211_cleanup(&nlstate);
901 ifr.ifr_flags |= IFF_UP|IFF_RUNNING;
902 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
903 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
904 "%s: Can't set flags for %s: %s", device,
905 handle->md.mondevice, strerror(errno));
906 del_mon_if(handle, sock_fd, &nlstate, device,
907 handle->md.mondevice);
908 nl80211_cleanup(&nlstate);
913 * Success. Clean up the libnl state.
915 nl80211_cleanup(&nlstate);
918 * Note that we have to delete the monitor device when we close
921 handle->md.must_do_on_close |= MUST_DELETE_MONIF;
924 * Add this to the list of pcaps to close when we exit.
926 pcap_add_to_pcaps_to_close(handle);
930 #endif /* HAVE_LIBNL */
933 pcap_can_set_rfmon_linux(pcap_t *handle)
936 char phydev_path[PATH_MAX+1];
939 #ifdef IW_MODE_MONITOR
944 if (strcmp(handle->opt.source, "any") == 0) {
946 * Monitor mode makes no sense on the "any" device.
953 * Bleah. There doesn't seem to be a way to ask a mac80211
954 * device, through libnl, whether it supports monitor mode;
955 * we'll just check whether the device appears to be a
956 * mac80211 device and, if so, assume the device supports
959 * wmaster devices don't appear to support the Wireless
960 * Extensions, but we can create a mon device for a
961 * wmaster device, so we don't bother checking whether
962 * a mac80211 device supports the Wireless Extensions.
964 ret = get_mac80211_phydev(handle, handle->opt.source, phydev_path,
967 return ret; /* error */
969 return 1; /* mac80211 device */
972 #ifdef IW_MODE_MONITOR
974 * Bleah. There doesn't appear to be an ioctl to use to ask
975 * whether a device supports monitor mode; we'll just do
976 * SIOCGIWMODE and, if it succeeds, assume the device supports
979 * Open a socket on which to attempt to get the mode.
980 * (We assume that if we have Wireless Extensions support
981 * we also have PF_PACKET support.)
983 sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
985 (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
986 "socket: %s", pcap_strerror(errno));
991 * Attempt to get the current mode.
993 strncpy(ireq.ifr_ifrn.ifrn_name, handle->opt.source,
994 sizeof ireq.ifr_ifrn.ifrn_name);
995 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
996 if (ioctl(sock_fd, SIOCGIWMODE, &ireq) != -1) {
998 * Well, we got the mode; assume we can set it.
1003 if (errno == ENODEV) {
1004 /* The device doesn't even exist. */
1005 (void)snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1006 "SIOCGIWMODE failed: %s", pcap_strerror(errno));
1008 return PCAP_ERROR_NO_SUCH_DEVICE;
1016 * Grabs the number of dropped packets by the interface from /proc/net/dev.
1018 * XXX - what about /sys/class/net/{interface name}/rx_*? There are
1019 * individual devices giving, in ASCII, various rx_ and tx_ statistics.
1021 * Or can we get them in binary form from netlink?
1024 linux_if_drops(const char * if_name)
1029 int field_to_convert = 3, if_name_sz = strlen(if_name);
1030 long int dropped_pkts = 0;
1032 file = fopen("/proc/net/dev", "r");
1036 while (!dropped_pkts && fgets( buffer, sizeof(buffer), file ))
1038 /* search for 'bytes' -- if its in there, then
1039 that means we need to grab the fourth field. otherwise
1040 grab the third field. */
1041 if (field_to_convert != 4 && strstr(buffer, "bytes"))
1043 field_to_convert = 4;
1047 /* find iface and make sure it actually matches -- space before the name and : after it */
1048 if ((bufptr = strstr(buffer, if_name)) &&
1049 (bufptr == buffer || *(bufptr-1) == ' ') &&
1050 *(bufptr + if_name_sz) == ':')
1052 bufptr = bufptr + if_name_sz + 1;
1054 /* grab the nth field from it */
1055 while( --field_to_convert && *bufptr != '\0')
1057 while (*bufptr != '\0' && *(bufptr++) == ' ');
1058 while (*bufptr != '\0' && *(bufptr++) != ' ');
1061 /* get rid of any final spaces */
1062 while (*bufptr != '\0' && *bufptr == ' ') bufptr++;
1064 if (*bufptr != '\0')
1065 dropped_pkts = strtol(bufptr, NULL, 10);
1072 return dropped_pkts;
1077 * With older kernels promiscuous mode is kind of interesting because we
1078 * have to reset the interface before exiting. The problem can't really
1079 * be solved without some daemon taking care of managing usage counts.
1080 * If we put the interface into promiscuous mode, we set a flag indicating
1081 * that we must take it out of that mode when the interface is closed,
1082 * and, when closing the interface, if that flag is set we take it out
1083 * of promiscuous mode.
1085 * Even with newer kernels, we have the same issue with rfmon mode.
1088 static void pcap_cleanup_linux( pcap_t *handle )
1092 struct nl80211_state nlstate;
1094 #endif /* HAVE_LIBNL */
1095 #ifdef IW_MODE_MONITOR
1098 #endif /* IW_MODE_MONITOR */
1100 if (handle->md.must_do_on_close != 0) {
1102 * There's something we have to do when closing this
1105 if (handle->md.must_do_on_close & MUST_CLEAR_PROMISC) {
1107 * We put the interface into promiscuous mode;
1108 * take it out of promiscuous mode.
1110 * XXX - if somebody else wants it in promiscuous
1111 * mode, this code cannot know that, so it'll take
1112 * it out of promiscuous mode. That's not fixable
1113 * in 2.0[.x] kernels.
1115 memset(&ifr, 0, sizeof(ifr));
1116 strncpy(ifr.ifr_name, handle->md.device,
1117 sizeof(ifr.ifr_name));
1118 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
1120 "Can't restore interface %s flags (SIOCGIFFLAGS failed: %s).\n"
1121 "Please adjust manually.\n"
1122 "Hint: This can't happen with Linux >= 2.2.0.\n",
1123 handle->md.device, strerror(errno));
1125 if (ifr.ifr_flags & IFF_PROMISC) {
1127 * Promiscuous mode is currently on;
1130 ifr.ifr_flags &= ~IFF_PROMISC;
1131 if (ioctl(handle->fd, SIOCSIFFLAGS,
1134 "Can't restore interface %s flags (SIOCSIFFLAGS failed: %s).\n"
1135 "Please adjust manually.\n"
1136 "Hint: This can't happen with Linux >= 2.2.0.\n",
1145 if (handle->md.must_do_on_close & MUST_DELETE_MONIF) {
1146 ret = nl80211_init(handle, &nlstate, handle->md.device);
1148 ret = del_mon_if(handle, handle->fd, &nlstate,
1149 handle->md.device, handle->md.mondevice);
1150 nl80211_cleanup(&nlstate);
1154 "Can't delete monitor interface %s (%s).\n"
1155 "Please delete manually.\n",
1156 handle->md.mondevice, handle->errbuf);
1159 #endif /* HAVE_LIBNL */
1161 #ifdef IW_MODE_MONITOR
1162 if (handle->md.must_do_on_close & MUST_CLEAR_RFMON) {
1164 * We put the interface into rfmon mode;
1165 * take it out of rfmon mode.
1167 * XXX - if somebody else wants it in rfmon
1168 * mode, this code cannot know that, so it'll take
1169 * it out of rfmon mode.
1173 * First, take the interface down if it's up;
1174 * otherwise, we might get EBUSY.
1175 * If we get errors, just drive on and print
1176 * a warning if we can't restore the mode.
1179 memset(&ifr, 0, sizeof(ifr));
1180 strncpy(ifr.ifr_name, handle->md.device,
1181 sizeof(ifr.ifr_name));
1182 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) != -1) {
1183 if (ifr.ifr_flags & IFF_UP) {
1184 oldflags = ifr.ifr_flags;
1185 ifr.ifr_flags &= ~IFF_UP;
1186 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1)
1187 oldflags = 0; /* didn't set, don't restore */
1192 * Now restore the mode.
1194 strncpy(ireq.ifr_ifrn.ifrn_name, handle->md.device,
1195 sizeof ireq.ifr_ifrn.ifrn_name);
1196 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1]
1198 ireq.u.mode = handle->md.oldmode;
1199 if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) {
1201 * Scientist, you've failed.
1204 "Can't restore interface %s wireless mode (SIOCSIWMODE failed: %s).\n"
1205 "Please adjust manually.\n",
1206 handle->md.device, strerror(errno));
1210 * Now bring the interface back up if we brought
1213 if (oldflags != 0) {
1214 ifr.ifr_flags = oldflags;
1215 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
1217 "Can't bring interface %s back up (SIOCSIFFLAGS failed: %s).\n"
1218 "Please adjust manually.\n",
1219 handle->md.device, strerror(errno));
1223 #endif /* IW_MODE_MONITOR */
1226 * Take this pcap out of the list of pcaps for which we
1227 * have to take the interface out of some mode.
1229 pcap_remove_from_pcaps_to_close(handle);
1232 if (handle->md.mondevice != NULL) {
1233 free(handle->md.mondevice);
1234 handle->md.mondevice = NULL;
1236 if (handle->md.device != NULL) {
1237 free(handle->md.device);
1238 handle->md.device = NULL;
1240 pcap_cleanup_live_common(handle);
1244 * Get a handle for a live capture from the given device. You can
1245 * pass NULL as device to get all packages (without link level
1246 * information of course). If you pass 1 as promisc the interface
1247 * will be set to promiscous mode (XXX: I think this usage should
1248 * be deprecated and functions be added to select that later allow
1249 * modification of that values -- Torsten).
1252 pcap_activate_linux(pcap_t *handle)
1257 device = handle->opt.source;
1259 handle->inject_op = pcap_inject_linux;
1260 handle->setfilter_op = pcap_setfilter_linux;
1261 handle->setdirection_op = pcap_setdirection_linux;
1262 handle->set_datalink_op = NULL; /* can't change data link type */
1263 handle->getnonblock_op = pcap_getnonblock_fd;
1264 handle->setnonblock_op = pcap_setnonblock_fd;
1265 handle->cleanup_op = pcap_cleanup_linux;
1266 handle->read_op = pcap_read_linux;
1267 handle->stats_op = pcap_stats_linux;
1270 * The "any" device is a special device which causes us not
1271 * to bind to a particular device and thus to look at all
1274 if (strcmp(device, "any") == 0) {
1275 if (handle->opt.promisc) {
1276 handle->opt.promisc = 0;
1277 /* Just a warning. */
1278 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1279 "Promiscuous mode not supported on the \"any\" device");
1280 status = PCAP_WARNING_PROMISC_NOTSUP;
1284 handle->md.device = strdup(device);
1285 if (handle->md.device == NULL) {
1286 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "strdup: %s",
1287 pcap_strerror(errno) );
1292 * If we're in promiscuous mode, then we probably want
1293 * to see when the interface drops packets too, so get an
1294 * initial count from /proc/net/dev
1296 if (handle->opt.promisc)
1297 handle->md.proc_dropped = linux_if_drops(handle->md.device);
1300 * Current Linux kernels use the protocol family PF_PACKET to
1301 * allow direct access to all packets on the network while
1302 * older kernels had a special socket type SOCK_PACKET to
1303 * implement this feature.
1304 * While this old implementation is kind of obsolete we need
1305 * to be compatible with older kernels for a while so we are
1306 * trying both methods with the newer method preferred.
1308 status = activate_new(handle);
1311 * Fatal error with the new way; just fail.
1312 * status has the error return; if it's PCAP_ERROR,
1313 * handle->errbuf has been set appropriately.
1320 * Try to use memory-mapped access.
1322 switch (activate_mmap(handle, &status)) {
1326 * We succeeded. status has been
1327 * set to the status to return,
1328 * which might be 0, or might be
1329 * a PCAP_WARNING_ value.
1335 * Kernel doesn't support it - just continue
1336 * with non-memory-mapped access.
1342 * We failed to set up to use it, or the kernel
1343 * supports it, but we failed to enable it.
1344 * status has been set to the error status to
1345 * return and, if it's PCAP_ERROR, handle->errbuf
1346 * contains the error message.
1351 else if (status == 0) {
1352 /* Non-fatal error; try old way */
1353 if ((status = activate_old(handle)) != 1) {
1355 * Both methods to open the packet socket failed.
1356 * Tidy up and report our failure (handle->errbuf
1357 * is expected to be set by the functions above).
1364 * We set up the socket, but not with memory-mapped access.
1367 if (handle->opt.buffer_size != 0) {
1369 * Set the socket buffer size to the specified value.
1371 if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF,
1372 &handle->opt.buffer_size,
1373 sizeof(handle->opt.buffer_size)) == -1) {
1374 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1375 "SO_RCVBUF: %s", pcap_strerror(errno));
1376 status = PCAP_ERROR;
1381 /* Allocate the buffer */
1383 handle->buffer = malloc(handle->bufsize + handle->offset);
1384 if (!handle->buffer) {
1385 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1386 "malloc: %s", pcap_strerror(errno));
1387 status = PCAP_ERROR;
1392 * "handle->fd" is a socket, so "select()" and "poll()"
1393 * should work on it.
1395 handle->selectable_fd = handle->fd;
1400 pcap_cleanup_linux(handle);
1405 * Read at most max_packets from the capture stream and call the callback
1406 * for each of them. Returns the number of packets handled or -1 if an
1410 pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
1413 * Currently, on Linux only one packet is delivered per read,
1416 return pcap_read_packet(handle, callback, user);
1420 * Read a packet from the socket calling the handler provided by
1421 * the user. Returns the number of packets received or -1 if an
1425 pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
1429 #ifdef HAVE_PF_PACKET_SOCKETS
1430 struct sockaddr_ll from;
1431 struct sll_header *hdrp;
1433 struct sockaddr from;
1435 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
1438 struct cmsghdr *cmsg;
1440 struct cmsghdr cmsg;
1441 char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))];
1443 #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
1445 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
1446 int packet_len, caplen;
1447 struct pcap_pkthdr pcap_header;
1449 #ifdef HAVE_PF_PACKET_SOCKETS
1451 * If this is a cooked device, leave extra room for a
1452 * fake packet header.
1454 if (handle->md.cooked)
1455 offset = SLL_HDR_LEN;
1460 * This system doesn't have PF_PACKET sockets, so it doesn't
1461 * support cooked devices.
1467 * Receive a single packet from the kernel.
1468 * We ignore EINTR, as that might just be due to a signal
1469 * being delivered - if the signal should interrupt the
1470 * loop, the signal handler should call pcap_breakloop()
1471 * to set handle->break_loop (we ignore it on other
1472 * platforms as well).
1473 * We also ignore ENETDOWN, so that we can continue to
1474 * capture traffic if the interface goes down and comes
1475 * back up again; comments in the kernel indicate that
1476 * we'll just block waiting for packets if we try to
1477 * receive from a socket that delivered ENETDOWN, and,
1478 * if we're using a memory-mapped buffer, we won't even
1479 * get notified of "network down" events.
1481 bp = handle->buffer + handle->offset;
1483 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
1484 msg.msg_name = &from;
1485 msg.msg_namelen = sizeof(from);
1488 msg.msg_control = &cmsg_buf;
1489 msg.msg_controllen = sizeof(cmsg_buf);
1492 iov.iov_len = handle->bufsize - offset;
1493 iov.iov_base = bp + offset;
1494 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
1498 * Has "pcap_breakloop()" been called?
1500 if (handle->break_loop) {
1502 * Yes - clear the flag that indicates that it has,
1503 * and return PCAP_ERROR_BREAK as an indication that
1504 * we were told to break out of the loop.
1506 handle->break_loop = 0;
1507 return PCAP_ERROR_BREAK;
1510 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
1511 packet_len = recvmsg(handle->fd, &msg, MSG_TRUNC);
1512 #else /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
1513 fromlen = sizeof(from);
1514 packet_len = recvfrom(
1515 handle->fd, bp + offset,
1516 handle->bufsize - offset, MSG_TRUNC,
1517 (struct sockaddr *) &from, &fromlen);
1518 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
1519 } while (packet_len == -1 && errno == EINTR);
1521 /* Check if an error occured */
1523 if (packet_len == -1) {
1527 return 0; /* no packet there */
1531 * The device on which we're capturing went away.
1533 * XXX - we should really return
1534 * PCAP_ERROR_IFACE_NOT_UP, but pcap_dispatch()
1535 * etc. aren't defined to return that.
1537 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1538 "The interface went down");
1542 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1543 "recvfrom: %s", pcap_strerror(errno));
1548 #ifdef HAVE_PF_PACKET_SOCKETS
1549 if (!handle->md.sock_packet) {
1551 * Unfortunately, there is a window between socket() and
1552 * bind() where the kernel may queue packets from any
1553 * interface. If we're bound to a particular interface,
1554 * discard packets not from that interface.
1556 * (If socket filters are supported, we could do the
1557 * same thing we do when changing the filter; however,
1558 * that won't handle packet sockets without socket
1559 * filter support, and it's a bit more complicated.
1560 * It would save some instructions per packet, however.)
1562 if (handle->md.ifindex != -1 &&
1563 from.sll_ifindex != handle->md.ifindex)
1567 * Do checks based on packet direction.
1568 * We can only do this if we're using PF_PACKET; the
1569 * address returned for SOCK_PACKET is a "sockaddr_pkt"
1570 * which lacks the relevant packet type information.
1572 if (from.sll_pkttype == PACKET_OUTGOING) {
1575 * If this is from the loopback device, reject it;
1576 * we'll see the packet as an incoming packet as well,
1577 * and we don't want to see it twice.
1579 if (from.sll_ifindex == handle->md.lo_ifindex)
1583 * If the user only wants incoming packets, reject it.
1585 if (handle->direction == PCAP_D_IN)
1590 * If the user only wants outgoing packets, reject it.
1592 if (handle->direction == PCAP_D_OUT)
1598 #ifdef HAVE_PF_PACKET_SOCKETS
1600 * If this is a cooked device, fill in the fake packet header.
1602 if (handle->md.cooked) {
1604 * Add the length of the fake header to the length
1605 * of packet data we read.
1607 packet_len += SLL_HDR_LEN;
1609 hdrp = (struct sll_header *)bp;
1610 hdrp->sll_pkttype = map_packet_type_to_sll_type(from.sll_pkttype);
1611 hdrp->sll_hatype = htons(from.sll_hatype);
1612 hdrp->sll_halen = htons(from.sll_halen);
1613 memcpy(hdrp->sll_addr, from.sll_addr,
1614 (from.sll_halen > SLL_ADDRLEN) ?
1617 hdrp->sll_protocol = from.sll_protocol;
1620 #if defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI)
1621 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
1622 struct tpacket_auxdata *aux;
1624 struct vlan_tag *tag;
1626 if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) ||
1627 cmsg->cmsg_level != SOL_PACKET ||
1628 cmsg->cmsg_type != PACKET_AUXDATA)
1631 aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg);
1632 if (aux->tp_vlan_tci == 0)
1635 len = packet_len > iov.iov_len ? iov.iov_len : packet_len;
1636 if (len < 2 * ETH_ALEN)
1640 memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN);
1642 tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN);
1643 tag->vlan_tpid = htons(ETH_P_8021Q);
1644 tag->vlan_tci = htons(aux->tp_vlan_tci);
1646 packet_len += VLAN_TAG_LEN;
1648 #endif /* defined(HAVE_PACKET_AUXDATA) && defined(HAVE_LINUX_TPACKET_AUXDATA_TP_VLAN_TCI) */
1649 #endif /* HAVE_PF_PACKET_SOCKETS */
1652 * XXX: According to the kernel source we should get the real
1653 * packet len if calling recvfrom with MSG_TRUNC set. It does
1654 * not seem to work here :(, but it is supported by this code
1656 * To be honest the code RELIES on that feature so this is really
1657 * broken with 2.2.x kernels.
1658 * I spend a day to figure out what's going on and I found out
1659 * that the following is happening:
1661 * The packet comes from a random interface and the packet_rcv
1662 * hook is called with a clone of the packet. That code inserts
1663 * the packet into the receive queue of the packet socket.
1664 * If a filter is attached to that socket that filter is run
1665 * first - and there lies the problem. The default filter always
1666 * cuts the packet at the snaplen:
1671 * So the packet filter cuts down the packet. The recvfrom call
1672 * says "hey, it's only 68 bytes, it fits into the buffer" with
1673 * the result that we don't get the real packet length. This
1674 * is valid at least until kernel 2.2.17pre6.
1676 * We currently handle this by making a copy of the filter
1677 * program, fixing all "ret" instructions with non-zero
1678 * operands to have an operand of 65535 so that the filter
1679 * doesn't truncate the packet, and supplying that modified
1680 * filter to the kernel.
1683 caplen = packet_len;
1684 if (caplen > handle->snapshot)
1685 caplen = handle->snapshot;
1687 /* Run the packet filter if not using kernel filter */
1688 if (!handle->md.use_bpf && handle->fcode.bf_insns) {
1689 if (bpf_filter(handle->fcode.bf_insns, bp,
1690 packet_len, caplen) == 0)
1692 /* rejected by filter */
1697 /* Fill in our own header data */
1699 if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) {
1700 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1701 "SIOCGSTAMP: %s", pcap_strerror(errno));
1704 pcap_header.caplen = caplen;
1705 pcap_header.len = packet_len;
1710 * Arguably, we should count them before we check the filter,
1711 * as on many other platforms "ps_recv" counts packets
1712 * handed to the filter rather than packets that passed
1713 * the filter, but if filtering is done in the kernel, we
1714 * can't get a count of packets that passed the filter,
1715 * and that would mean the meaning of "ps_recv" wouldn't
1716 * be the same on all Linux systems.
1718 * XXX - it's not the same on all systems in any case;
1719 * ideally, we should have a "get the statistics" call
1720 * that supplies more counts and indicates which of them
1721 * it supplies, so that we supply a count of packets
1722 * handed to the filter only on platforms where that
1723 * information is available.
1725 * We count them here even if we can get the packet count
1726 * from the kernel, as we can only determine at run time
1727 * whether we'll be able to get it from the kernel (if
1728 * HAVE_TPACKET_STATS isn't defined, we can't get it from
1729 * the kernel, but if it is defined, the library might
1730 * have been built with a 2.4 or later kernel, but we
1731 * might be running on a 2.2[.x] kernel without Alexey
1732 * Kuznetzov's turbopacket patches, and thus the kernel
1733 * might not be able to supply those statistics). We
1734 * could, I guess, try, when opening the socket, to get
1735 * the statistics, and if we can not increment the count
1736 * here, but it's not clear that always incrementing
1737 * the count is more expensive than always testing a flag
1740 * We keep the count in "md.packets_read", and use that for
1741 * "ps_recv" if we can't get the statistics from the kernel.
1742 * We do that because, if we *can* get the statistics from
1743 * the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop"
1744 * as running counts, as reading the statistics from the
1745 * kernel resets the kernel statistics, and if we directly
1746 * increment "md.stat.ps_recv" here, that means it will
1747 * count packets *twice* on systems where we can get kernel
1748 * statistics - once here, and once in pcap_stats_linux().
1750 handle->md.packets_read++;
1752 /* Call the user supplied callback function */
1753 callback(userdata, &pcap_header, bp);
1759 pcap_inject_linux(pcap_t *handle, const void *buf, size_t size)
1763 #ifdef HAVE_PF_PACKET_SOCKETS
1764 if (!handle->md.sock_packet) {
1765 /* PF_PACKET socket */
1766 if (handle->md.ifindex == -1) {
1768 * We don't support sending on the "any" device.
1770 strlcpy(handle->errbuf,
1771 "Sending packets isn't supported on the \"any\" device",
1776 if (handle->md.cooked) {
1778 * We don't support sending on the "any" device.
1780 * XXX - how do you send on a bound cooked-mode
1782 * Is a "sendto()" required there?
1784 strlcpy(handle->errbuf,
1785 "Sending packets isn't supported in cooked mode",
1792 ret = send(handle->fd, buf, size, 0);
1794 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
1795 pcap_strerror(errno));
1802 * Get the statistics for the given packet capture handle.
1803 * Reports the number of dropped packets iff the kernel supports
1804 * the PACKET_STATISTICS "getsockopt()" argument (2.4 and later
1805 * kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket
1806 * patches); otherwise, that information isn't available, and we lie
1807 * and report 0 as the count of dropped packets.
1810 pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
1812 #ifdef HAVE_TPACKET_STATS
1813 struct tpacket_stats kstats;
1814 socklen_t len = sizeof (struct tpacket_stats);
1817 long if_dropped = 0;
1820 * To fill in ps_ifdrop, we parse /proc/net/dev for the number
1822 if (handle->opt.promisc)
1824 if_dropped = handle->md.proc_dropped;
1825 handle->md.proc_dropped = linux_if_drops(handle->md.device);
1826 handle->md.stat.ps_ifdrop += (handle->md.proc_dropped - if_dropped);
1829 #ifdef HAVE_TPACKET_STATS
1831 * Try to get the packet counts from the kernel.
1833 if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
1834 &kstats, &len) > -1) {
1836 * On systems where the PACKET_STATISTICS "getsockopt()"
1837 * argument is supported on PF_PACKET sockets:
1839 * "ps_recv" counts only packets that *passed* the
1840 * filter, not packets that didn't pass the filter.
1841 * This includes packets later dropped because we
1842 * ran out of buffer space.
1844 * "ps_drop" counts packets dropped because we ran
1845 * out of buffer space. It doesn't count packets
1846 * dropped by the interface driver. It counts only
1847 * packets that passed the filter.
1849 * See above for ps_ifdrop.
1851 * Both statistics include packets not yet read from
1852 * the kernel by libpcap, and thus not yet seen by
1855 * In "linux/net/packet/af_packet.c", at least in the
1856 * 2.4.9 kernel, "tp_packets" is incremented for every
1857 * packet that passes the packet filter *and* is
1858 * successfully queued on the socket; "tp_drops" is
1859 * incremented for every packet dropped because there's
1860 * not enough free space in the socket buffer.
1862 * When the statistics are returned for a PACKET_STATISTICS
1863 * "getsockopt()" call, "tp_drops" is added to "tp_packets",
1864 * so that "tp_packets" counts all packets handed to
1865 * the PF_PACKET socket, including packets dropped because
1866 * there wasn't room on the socket buffer - but not
1867 * including packets that didn't pass the filter.
1869 * In the BSD BPF, the count of received packets is
1870 * incremented for every packet handed to BPF, regardless
1871 * of whether it passed the filter.
1873 * We can't make "pcap_stats()" work the same on both
1874 * platforms, but the best approximation is to return
1875 * "tp_packets" as the count of packets and "tp_drops"
1876 * as the count of drops.
1878 * Keep a running total because each call to
1879 * getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, ....
1880 * resets the counters to zero.
1882 handle->md.stat.ps_recv += kstats.tp_packets;
1883 handle->md.stat.ps_drop += kstats.tp_drops;
1884 *stats = handle->md.stat;
1890 * If the error was EOPNOTSUPP, fall through, so that
1891 * if you build the library on a system with
1892 * "struct tpacket_stats" and run it on a system
1893 * that doesn't, it works as it does if the library
1894 * is built on a system without "struct tpacket_stats".
1896 if (errno != EOPNOTSUPP) {
1897 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
1898 "pcap_stats: %s", pcap_strerror(errno));
1904 * On systems where the PACKET_STATISTICS "getsockopt()" argument
1905 * is not supported on PF_PACKET sockets:
1907 * "ps_recv" counts only packets that *passed* the filter,
1908 * not packets that didn't pass the filter. It does not
1909 * count packets dropped because we ran out of buffer
1912 * "ps_drop" is not supported.
1914 * "ps_ifdrop" is supported. It will return the number
1915 * of drops the interface reports in /proc/net/dev,
1916 * if that is available.
1918 * "ps_recv" doesn't include packets not yet read from
1919 * the kernel by libpcap.
1921 * We maintain the count of packets processed by libpcap in
1922 * "md.packets_read", for reasons described in the comment
1923 * at the end of pcap_read_packet(). We have no idea how many
1924 * packets were dropped by the kernel buffers -- but we know
1925 * how many the interface dropped, so we can return that.
1928 stats->ps_recv = handle->md.packets_read;
1930 stats->ps_ifdrop = handle->md.stat.ps_ifdrop;
1935 * Get from "/sys/class/net" all interfaces listed there; if they're
1936 * already in the list of interfaces we have, that won't add another
1937 * instance, but if they're not, that'll add them.
1939 * We don't bother getting any addresses for them; it appears you can't
1940 * use SIOCGIFADDR on Linux to get IPv6 addresses for interfaces, and,
1941 * although some other types of addresses can be fetched with SIOCGIFADDR,
1942 * we don't bother with them for now.
1944 * We also don't fail if we couldn't open "/sys/class/net"; we just leave
1945 * the list of interfaces as is, and return 0, so that we can try
1946 * scanning /proc/net/dev.
1949 scan_sys_class_net(pcap_if_t **devlistp, char *errbuf)
1951 DIR *sys_class_net_d;
1955 char name[512]; /* XXX - pick a size */
1957 struct ifreq ifrflags;
1960 sys_class_net_d = opendir("/sys/class/net");
1961 if (sys_class_net_d == NULL) {
1963 * Don't fail if it doesn't exist at all.
1965 if (errno == ENOENT)
1969 * Fail if we got some other error.
1971 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
1972 "Can't open /sys/class/net: %s", pcap_strerror(errno));
1977 * Create a socket from which to fetch interface information.
1979 fd = socket(AF_INET, SOCK_DGRAM, 0);
1981 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
1982 "socket: %s", pcap_strerror(errno));
1983 (void)closedir(sys_class_net_d);
1989 ent = readdir(sys_class_net_d);
1992 * Error or EOF; if errno != 0, it's an error.
1998 * Ignore directories (".", "..", and any subdirectories).
2000 if (ent->d_type == DT_DIR)
2004 * Get the interface name.
2006 p = &ent->d_name[0];
2008 while (*p != '\0' && isascii(*p) && !isspace(*p)) {
2011 * This could be the separator between a
2012 * name and an alias number, or it could be
2013 * the separator between a name with no
2014 * alias number and the next field.
2016 * If there's a colon after digits, it
2017 * separates the name and the alias number,
2018 * otherwise it separates the name and the
2022 while (isascii(*p) && isdigit(*p))
2026 * That was the next field,
2027 * not the alias number.
2038 * Get the flags for this interface, and skip it if
2041 strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name));
2042 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
2043 if (errno == ENXIO || errno == ENODEV)
2045 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
2046 "SIOCGIFFLAGS: %.*s: %s",
2047 (int)sizeof(ifrflags.ifr_name),
2049 pcap_strerror(errno));
2053 if (!(ifrflags.ifr_flags & IFF_UP))
2057 * Add an entry for this interface, with no addresses.
2059 if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL,
2070 * Well, we didn't fail for any other reason; did we
2071 * fail due to an error reading the directory?
2074 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
2075 "Error reading /sys/class/net: %s",
2076 pcap_strerror(errno));
2082 (void)closedir(sys_class_net_d);
2087 * Get from "/proc/net/dev" all interfaces listed there; if they're
2088 * already in the list of interfaces we have, that won't add another
2089 * instance, but if they're not, that'll add them.
2091 * See comments from scan_sys_class_net().
2094 scan_proc_net_dev(pcap_if_t **devlistp, char *errbuf)
2101 char name[512]; /* XXX - pick a size */
2103 struct ifreq ifrflags;
2106 proc_net_f = fopen("/proc/net/dev", "r");
2107 if (proc_net_f == NULL) {
2109 * Don't fail if it doesn't exist at all.
2111 if (errno == ENOENT)
2115 * Fail if we got some other error.
2117 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
2118 "Can't open /proc/net/dev: %s", pcap_strerror(errno));
2123 * Create a socket from which to fetch interface information.
2125 fd = socket(AF_INET, SOCK_DGRAM, 0);
2127 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
2128 "socket: %s", pcap_strerror(errno));
2129 (void)fclose(proc_net_f);
2134 fgets(linebuf, sizeof linebuf, proc_net_f) != NULL; linenum++) {
2136 * Skip the first two lines - they're headers.
2144 * Skip leading white space.
2146 while (*p != '\0' && isascii(*p) && isspace(*p))
2148 if (*p == '\0' || *p == '\n')
2149 continue; /* blank line */
2152 * Get the interface name.
2155 while (*p != '\0' && isascii(*p) && !isspace(*p)) {
2158 * This could be the separator between a
2159 * name and an alias number, or it could be
2160 * the separator between a name with no
2161 * alias number and the next field.
2163 * If there's a colon after digits, it
2164 * separates the name and the alias number,
2165 * otherwise it separates the name and the
2169 while (isascii(*p) && isdigit(*p))
2173 * That was the next field,
2174 * not the alias number.
2185 * Get the flags for this interface, and skip it if
2188 strncpy(ifrflags.ifr_name, name, sizeof(ifrflags.ifr_name));
2189 if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
2192 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
2193 "SIOCGIFFLAGS: %.*s: %s",
2194 (int)sizeof(ifrflags.ifr_name),
2196 pcap_strerror(errno));
2200 if (!(ifrflags.ifr_flags & IFF_UP))
2204 * Add an entry for this interface, with no addresses.
2206 if (pcap_add_if(devlistp, name, ifrflags.ifr_flags, NULL,
2217 * Well, we didn't fail for any other reason; did we
2218 * fail due to an error reading the file?
2220 if (ferror(proc_net_f)) {
2221 (void)snprintf(errbuf, PCAP_ERRBUF_SIZE,
2222 "Error reading /proc/net/dev: %s",
2223 pcap_strerror(errno));
2229 (void)fclose(proc_net_f);
2234 * Description string for the "any" device.
2236 static const char any_descr[] = "Pseudo-device that captures on all interfaces";
2239 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
2244 * Read "/sys/class/net", and add to the list of interfaces all
2245 * interfaces listed there that we don't already have, because,
2246 * on Linux, SIOCGIFCONF reports only interfaces with IPv4 addresses,
2247 * and even getifaddrs() won't return information about
2248 * interfaces with no addresses, so you need to read "/sys/class/net"
2249 * to get the names of the rest of the interfaces.
2251 ret = scan_sys_class_net(alldevsp, errbuf);
2253 return (-1); /* failed */
2256 * No /sys/class/net; try reading /proc/net/dev instead.
2258 if (scan_proc_net_dev(alldevsp, errbuf) == -1)
2263 * Add the "any" device.
2265 if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0)
2272 if (dag_platform_finddevs(alldevsp, errbuf) < 0)
2274 #endif /* HAVE_DAG_API */
2276 #ifdef HAVE_SEPTEL_API
2278 * Add Septel devices.
2280 if (septel_platform_finddevs(alldevsp, errbuf) < 0)
2282 #endif /* HAVE_SEPTEL_API */
2285 if (snf_platform_finddevs(alldevsp, errbuf) < 0)
2287 #endif /* HAVE_SNF_API */
2289 #ifdef PCAP_SUPPORT_BT
2291 * Add Bluetooth devices.
2293 if (bt_platform_finddevs(alldevsp, errbuf) < 0)
2297 #ifdef PCAP_SUPPORT_USB
2301 if (usb_platform_finddevs(alldevsp, errbuf) < 0)
2305 #ifdef PCAP_SUPPORT_NETFILTER
2307 * Add netfilter devices.
2309 if (netfilter_platform_finddevs(alldevsp, errbuf) < 0)
2313 #if PCAP_SUPPORT_CANUSB
2314 if (canusb_platform_finddevs(alldevsp, errbuf) < 0)
2322 * Attach the given BPF code to the packet capture device.
2325 pcap_setfilter_linux_common(pcap_t *handle, struct bpf_program *filter,
2328 #ifdef SO_ATTACH_FILTER
2329 struct sock_fprog fcode;
2330 int can_filter_in_kernel;
2337 strncpy(handle->errbuf, "setfilter: No filter specified",
2342 /* Make our private copy of the filter */
2344 if (install_bpf_program(handle, filter) < 0)
2345 /* install_bpf_program() filled in errbuf */
2349 * Run user level packet filter by default. Will be overriden if
2350 * installing a kernel filter succeeds.
2352 handle->md.use_bpf = 0;
2354 /* Install kernel level filter if possible */
2356 #ifdef SO_ATTACH_FILTER
2358 if (handle->fcode.bf_len > USHRT_MAX) {
2360 * fcode.len is an unsigned short for current kernel.
2361 * I have yet to see BPF-Code with that much
2362 * instructions but still it is possible. So for the
2363 * sake of correctness I added this check.
2365 fprintf(stderr, "Warning: Filter too complex for kernel\n");
2367 fcode.filter = NULL;
2368 can_filter_in_kernel = 0;
2370 #endif /* USHRT_MAX */
2373 * Oh joy, the Linux kernel uses struct sock_fprog instead
2374 * of struct bpf_program and of course the length field is
2375 * of different size. Pointed out by Sebastian
2377 * Oh, and we also need to fix it up so that all "ret"
2378 * instructions with non-zero operands have 65535 as the
2379 * operand if we're not capturing in memory-mapped modee,
2380 * and so that, if we're in cooked mode, all memory-reference
2381 * instructions use special magic offsets in references to
2382 * the link-layer header and assume that the link-layer
2383 * payload begins at 0; "fix_program()" will do that.
2385 switch (fix_program(handle, &fcode, is_mmapped)) {
2390 * Fatal error; just quit.
2391 * (The "default" case shouldn't happen; we
2392 * return -1 for that reason.)
2398 * The program performed checks that we can't make
2399 * work in the kernel.
2401 can_filter_in_kernel = 0;
2406 * We have a filter that'll work in the kernel.
2408 can_filter_in_kernel = 1;
2414 * NOTE: at this point, we've set both the "len" and "filter"
2415 * fields of "fcode". As of the 2.6.32.4 kernel, at least,
2416 * those are the only members of the "sock_fprog" structure,
2417 * so we initialize every member of that structure.
2419 * If there is anything in "fcode" that is not initialized,
2420 * it is either a field added in a later kernel, or it's
2423 * If a new field is added, this code needs to be updated
2424 * to set it correctly.
2426 * If there are no other fields, then:
2428 * if the Linux kernel looks at the padding, it's
2431 * if the Linux kernel doesn't look at the padding,
2432 * then if some tool complains that we're passing
2433 * uninitialized data to the kernel, then the tool
2434 * is buggy and needs to understand that it's just
2437 if (can_filter_in_kernel) {
2438 if ((err = set_kernel_filter(handle, &fcode)) == 0)
2440 /* Installation succeded - using kernel filter. */
2441 handle->md.use_bpf = 1;
2443 else if (err == -1) /* Non-fatal error */
2446 * Print a warning if we weren't able to install
2447 * the filter for a reason other than "this kernel
2448 * isn't configured to support socket filters.
2450 if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
2452 "Warning: Kernel filter failed: %s\n",
2453 pcap_strerror(errno));
2459 * If we're not using the kernel filter, get rid of any kernel
2460 * filter that might've been there before, e.g. because the
2461 * previous filter could work in the kernel, or because some other
2462 * code attached a filter to the socket by some means other than
2463 * calling "pcap_setfilter()". Otherwise, the kernel filter may
2464 * filter out packets that would pass the new userland filter.
2466 if (!handle->md.use_bpf)
2467 reset_kernel_filter(handle);
2470 * Free up the copy of the filter that was made by "fix_program()".
2472 if (fcode.filter != NULL)
2478 #endif /* SO_ATTACH_FILTER */
2484 pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
2486 return pcap_setfilter_linux_common(handle, filter, 0);
2491 * Set direction flag: Which packets do we accept on a forwarding
2492 * single device? IN, OUT or both?
2495 pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d)
2497 #ifdef HAVE_PF_PACKET_SOCKETS
2498 if (!handle->md.sock_packet) {
2499 handle->direction = d;
2504 * We're not using PF_PACKET sockets, so we can't determine
2505 * the direction of the packet.
2507 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
2508 "Setting direction is not supported on SOCK_PACKET sockets");
2512 #ifdef HAVE_PF_PACKET_SOCKETS
2514 * Map the PACKET_ value to a LINUX_SLL_ value; we
2515 * want the same numerical value to be used in
2516 * the link-layer header even if the numerical values
2517 * for the PACKET_ #defines change, so that programs
2518 * that look at the packet type field will always be
2519 * able to handle DLT_LINUX_SLL captures.
2522 map_packet_type_to_sll_type(short int sll_pkttype)
2524 switch (sll_pkttype) {
2527 return htons(LINUX_SLL_HOST);
2529 case PACKET_BROADCAST:
2530 return htons(LINUX_SLL_BROADCAST);
2532 case PACKET_MULTICAST:
2533 return htons(LINUX_SLL_MULTICAST);
2535 case PACKET_OTHERHOST:
2536 return htons(LINUX_SLL_OTHERHOST);
2538 case PACKET_OUTGOING:
2539 return htons(LINUX_SLL_OUTGOING);
2548 * Linux uses the ARP hardware type to identify the type of an
2549 * interface. pcap uses the DLT_xxx constants for this. This
2550 * function takes a pointer to a "pcap_t", and an ARPHRD_xxx
2551 * constant, as arguments, and sets "handle->linktype" to the
2552 * appropriate DLT_XXX constant and sets "handle->offset" to
2553 * the appropriate value (to make "handle->offset" plus link-layer
2554 * header length be a multiple of 4, so that the link-layer payload
2555 * will be aligned on a 4-byte boundary when capturing packets).
2556 * (If the offset isn't set here, it'll be 0; add code as appropriate
2557 * for cases where it shouldn't be 0.)
2559 * If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture
2560 * in cooked mode; otherwise, we can't use cooked mode, so we have
2561 * to pick some type that works in raw mode, or fail.
2563 * Sets the link type to -1 if unable to map the type.
2565 static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok)
2571 * This is (presumably) a real Ethernet capture; give it a
2572 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
2573 * that an application can let you choose it, in case you're
2574 * capturing DOCSIS traffic that a Cisco Cable Modem
2575 * Termination System is putting out onto an Ethernet (it
2576 * doesn't put an Ethernet header onto the wire, it puts raw
2577 * DOCSIS frames out on the wire inside the low-level
2578 * Ethernet framing).
2580 * XXX - are there any sorts of "fake Ethernet" that have
2581 * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as
2582 * a Cisco CMTS won't put traffic onto it or get traffic
2583 * bridged onto it? ISDN is handled in "activate_new()",
2584 * as we fall back on cooked mode there; are there any
2587 handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
2589 * If that fails, just leave the list empty.
2591 if (handle->dlt_list != NULL) {
2592 handle->dlt_list[0] = DLT_EN10MB;
2593 handle->dlt_list[1] = DLT_DOCSIS;
2594 handle->dlt_count = 2;
2598 case ARPHRD_METRICOM:
2599 case ARPHRD_LOOPBACK:
2600 handle->linktype = DLT_EN10MB;
2605 handle->linktype = DLT_EN3MB;
2609 handle->linktype = DLT_AX25_KISS;
2613 handle->linktype = DLT_PRONET;
2617 handle->linktype = DLT_CHAOS;
2620 #define ARPHRD_CAN 280
2623 handle->linktype = DLT_CAN_SOCKETCAN;
2626 #ifndef ARPHRD_IEEE802_TR
2627 #define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */
2629 case ARPHRD_IEEE802_TR:
2630 case ARPHRD_IEEE802:
2631 handle->linktype = DLT_IEEE802;
2636 handle->linktype = DLT_ARCNET_LINUX;
2639 #ifndef ARPHRD_FDDI /* From Linux 2.2.13 */
2640 #define ARPHRD_FDDI 774
2643 handle->linktype = DLT_FDDI;
2647 #ifndef ARPHRD_ATM /* FIXME: How to #include this? */
2648 #define ARPHRD_ATM 19
2652 * The Classical IP implementation in ATM for Linux
2653 * supports both what RFC 1483 calls "LLC Encapsulation",
2654 * in which each packet has an LLC header, possibly
2655 * with a SNAP header as well, prepended to it, and
2656 * what RFC 1483 calls "VC Based Multiplexing", in which
2657 * different virtual circuits carry different network
2658 * layer protocols, and no header is prepended to packets.
2660 * They both have an ARPHRD_ type of ARPHRD_ATM, so
2661 * you can't use the ARPHRD_ type to find out whether
2662 * captured packets will have an LLC header, and,
2663 * while there's a socket ioctl to *set* the encapsulation
2664 * type, there's no ioctl to *get* the encapsulation type.
2668 * programs that dissect Linux Classical IP frames
2669 * would have to check for an LLC header and,
2670 * depending on whether they see one or not, dissect
2671 * the frame as LLC-encapsulated or as raw IP (I
2672 * don't know whether there's any traffic other than
2673 * IP that would show up on the socket, or whether
2674 * there's any support for IPv6 in the Linux
2675 * Classical IP code);
2677 * filter expressions would have to compile into
2678 * code that checks for an LLC header and does
2681 * Both of those are a nuisance - and, at least on systems
2682 * that support PF_PACKET sockets, we don't have to put
2683 * up with those nuisances; instead, we can just capture
2684 * in cooked mode. That's what we'll do, if we can.
2685 * Otherwise, we'll just fail.
2688 handle->linktype = DLT_LINUX_SLL;
2690 handle->linktype = -1;
2693 #ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
2694 #define ARPHRD_IEEE80211 801
2696 case ARPHRD_IEEE80211:
2697 handle->linktype = DLT_IEEE802_11;
2700 #ifndef ARPHRD_IEEE80211_PRISM /* From Linux 2.4.18 */
2701 #define ARPHRD_IEEE80211_PRISM 802
2703 case ARPHRD_IEEE80211_PRISM:
2704 handle->linktype = DLT_PRISM_HEADER;
2707 #ifndef ARPHRD_IEEE80211_RADIOTAP /* new */
2708 #define ARPHRD_IEEE80211_RADIOTAP 803
2710 case ARPHRD_IEEE80211_RADIOTAP:
2711 handle->linktype = DLT_IEEE802_11_RADIO;
2716 * Some PPP code in the kernel supplies no link-layer
2717 * header whatsoever to PF_PACKET sockets; other PPP
2718 * code supplies PPP link-layer headers ("syncppp.c");
2719 * some PPP code might supply random link-layer
2720 * headers (PPP over ISDN - there's code in Ethereal,
2721 * for example, to cope with PPP-over-ISDN captures
2722 * with which the Ethereal developers have had to cope,
2723 * heuristically trying to determine which of the
2724 * oddball link-layer headers particular packets have).
2726 * As such, we just punt, and run all PPP interfaces
2727 * in cooked mode, if we can; otherwise, we just treat
2728 * it as DLT_RAW, for now - if somebody needs to capture,
2729 * on a 2.0[.x] kernel, on PPP devices that supply a
2730 * link-layer header, they'll have to add code here to
2731 * map to the appropriate DLT_ type (possibly adding a
2732 * new DLT_ type, if necessary).
2735 handle->linktype = DLT_LINUX_SLL;
2738 * XXX - handle ISDN types here? We can't fall
2739 * back on cooked sockets, so we'd have to
2740 * figure out from the device name what type of
2741 * link-layer encapsulation it's using, and map
2742 * that to an appropriate DLT_ value, meaning
2743 * we'd map "isdnN" devices to DLT_RAW (they
2744 * supply raw IP packets with no link-layer
2745 * header) and "isdY" devices to a new DLT_I4L_IP
2746 * type that has only an Ethernet packet type as
2747 * a link-layer header.
2749 * But sometimes we seem to get random crap
2750 * in the link-layer header when capturing on
2753 handle->linktype = DLT_RAW;
2757 #ifndef ARPHRD_CISCO
2758 #define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
2761 handle->linktype = DLT_C_HDLC;
2764 /* Not sure if this is correct for all tunnels, but it
2768 #define ARPHRD_SIT 776 /* From Linux 2.2.13 */
2776 #ifndef ARPHRD_RAWHDLC
2777 #define ARPHRD_RAWHDLC 518
2779 case ARPHRD_RAWHDLC:
2781 #define ARPHRD_DLCI 15
2785 * XXX - should some of those be mapped to DLT_LINUX_SLL
2786 * instead? Should we just map all of them to DLT_LINUX_SLL?
2788 handle->linktype = DLT_RAW;
2792 #define ARPHRD_FRAD 770
2795 handle->linktype = DLT_FRELAY;
2798 case ARPHRD_LOCALTLK:
2799 handle->linktype = DLT_LTALK;
2803 #define ARPHRD_FCPP 784
2807 #define ARPHRD_FCAL 785
2811 #define ARPHRD_FCPL 786
2814 #ifndef ARPHRD_FCFABRIC
2815 #define ARPHRD_FCFABRIC 787
2817 case ARPHRD_FCFABRIC:
2819 * We assume that those all mean RFC 2625 IP-over-
2820 * Fibre Channel, with the RFC 2625 header at
2821 * the beginning of the packet.
2823 handle->linktype = DLT_IP_OVER_FC;
2827 #define ARPHRD_IRDA 783
2830 /* Don't expect IP packet out of this interfaces... */
2831 handle->linktype = DLT_LINUX_IRDA;
2832 /* We need to save packet direction for IrDA decoding,
2833 * so let's use "Linux-cooked" mode. Jean II */
2834 //handle->md.cooked = 1;
2837 /* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation
2838 * is needed, please report it to <daniele@orlandi.com> */
2840 #define ARPHRD_LAPD 8445
2843 /* Don't expect IP packet out of this interfaces... */
2844 handle->linktype = DLT_LINUX_LAPD;
2848 #define ARPHRD_NONE 0xFFFE
2852 * No link-layer header; packets are just IP
2853 * packets, so use DLT_RAW.
2855 handle->linktype = DLT_RAW;
2858 #ifndef ARPHRD_IEEE802154
2859 #define ARPHRD_IEEE802154 804
2861 case ARPHRD_IEEE802154:
2862 handle->linktype = DLT_IEEE802_15_4_NOFCS;
2866 handle->linktype = -1;
2871 /* ===== Functions to interface to the newer kernels ================== */
2874 * Try to open a packet socket using the new kernel PF_PACKET interface.
2875 * Returns 1 on success, 0 on an error that means the new interface isn't
2876 * present (so the old SOCK_PACKET interface should be tried), and a
2877 * PCAP_ERROR_ value on an error that means that the old mechanism won't
2878 * work either (so it shouldn't be tried).
2881 activate_new(pcap_t *handle)
2883 #ifdef HAVE_PF_PACKET_SOCKETS
2884 const char *device = handle->opt.source;
2885 int is_any_device = (strcmp(device, "any") == 0);
2886 int sock_fd = -1, arptype;
2887 #ifdef HAVE_PACKET_AUXDATA
2891 struct packet_mreq mr;
2894 * Open a socket with protocol family packet. If the
2895 * "any" device was specified, we open a SOCK_DGRAM
2896 * socket for the cooked interface, otherwise we first
2897 * try a SOCK_RAW socket for the raw interface.
2899 sock_fd = is_any_device ?
2900 socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL)) :
2901 socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
2903 if (sock_fd == -1) {
2904 if (errno == EINVAL || errno == EAFNOSUPPORT) {
2906 * We don't support PF_PACKET/SOCK_whatever
2907 * sockets; try the old mechanism.
2912 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "socket: %s",
2913 pcap_strerror(errno) );
2914 if (errno == EPERM || errno == EACCES) {
2916 * You don't have permission to open the
2919 return PCAP_ERROR_PERM_DENIED;
2928 /* It seems the kernel supports the new interface. */
2929 handle->md.sock_packet = 0;
2932 * Get the interface index of the loopback device.
2933 * If the attempt fails, don't fail, just set the
2934 * "md.lo_ifindex" to -1.
2936 * XXX - can there be more than one device that loops
2937 * packets back, i.e. devices other than "lo"? If so,
2938 * we'd need to find them all, and have an array of
2939 * indices for them, and check all of them in
2940 * "pcap_read_packet()".
2942 handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", handle->errbuf);
2945 * Default value for offset to align link-layer payload
2946 * on a 4-byte boundary.
2951 * What kind of frames do we have to deal with? Fall back
2952 * to cooked mode if we have an unknown interface type
2953 * or a type we know doesn't work well in raw mode.
2955 if (!is_any_device) {
2956 /* Assume for now we don't need cooked mode. */
2957 handle->md.cooked = 0;
2959 if (handle->opt.rfmon) {
2961 * We were asked to turn on monitor mode.
2962 * Do so before we get the link-layer type,
2963 * because entering monitor mode could change
2964 * the link-layer type.
2966 err = enter_rfmon_mode(handle, sock_fd, device);
2974 * Nothing worked for turning monitor mode
2978 return PCAP_ERROR_RFMON_NOTSUP;
2982 * Either monitor mode has been turned on for
2983 * the device, or we've been given a different
2984 * device to open for monitor mode. If we've
2985 * been given a different device, use it.
2987 if (handle->md.mondevice != NULL)
2988 device = handle->md.mondevice;
2990 arptype = iface_get_arptype(sock_fd, device, handle->errbuf);
2995 map_arphrd_to_dlt(handle, arptype, 1);
2996 if (handle->linktype == -1 ||
2997 handle->linktype == DLT_LINUX_SLL ||
2998 handle->linktype == DLT_LINUX_IRDA ||
2999 handle->linktype == DLT_LINUX_LAPD ||
3000 (handle->linktype == DLT_EN10MB &&
3001 (strncmp("isdn", device, 4) == 0 ||
3002 strncmp("isdY", device, 4) == 0))) {
3004 * Unknown interface type (-1), or a
3005 * device we explicitly chose to run
3006 * in cooked mode (e.g., PPP devices),
3007 * or an ISDN device (whose link-layer
3008 * type we can only determine by using
3009 * APIs that may be different on different
3010 * kernels) - reopen in cooked mode.
3012 if (close(sock_fd) == -1) {
3013 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3014 "close: %s", pcap_strerror(errno));
3017 sock_fd = socket(PF_PACKET, SOCK_DGRAM,
3019 if (sock_fd == -1) {
3020 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3021 "socket: %s", pcap_strerror(errno));
3022 if (errno == EPERM || errno == EACCES) {
3024 * You don't have permission to
3027 return PCAP_ERROR_PERM_DENIED;
3035 handle->md.cooked = 1;
3038 * Get rid of any link-layer type list
3039 * we allocated - this only supports cooked
3042 if (handle->dlt_list != NULL) {
3043 free(handle->dlt_list);
3044 handle->dlt_list = NULL;
3045 handle->dlt_count = 0;
3048 if (handle->linktype == -1) {
3050 * Warn that we're falling back on
3051 * cooked mode; we may want to
3052 * update "map_arphrd_to_dlt()"
3053 * to handle the new type.
3055 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3057 "supported by libpcap - "
3058 "falling back to cooked "
3064 * IrDA capture is not a real "cooked" capture,
3065 * it's IrLAP frames, not IP packets. The
3066 * same applies to LAPD capture.
3068 if (handle->linktype != DLT_LINUX_IRDA &&
3069 handle->linktype != DLT_LINUX_LAPD)
3070 handle->linktype = DLT_LINUX_SLL;
3073 handle->md.ifindex = iface_get_id(sock_fd, device,
3075 if (handle->md.ifindex == -1) {
3080 if ((err = iface_bind(sock_fd, handle->md.ifindex,
3081 handle->errbuf)) != 1) {
3086 return 0; /* try old mechanism */
3092 if (handle->opt.rfmon) {
3094 * It doesn't support monitor mode.
3096 return PCAP_ERROR_RFMON_NOTSUP;
3100 * It uses cooked mode.
3102 handle->md.cooked = 1;
3103 handle->linktype = DLT_LINUX_SLL;
3106 * We're not bound to a device.
3107 * For now, we're using this as an indication
3108 * that we can't transmit; stop doing that only
3109 * if we figure out how to transmit in cooked
3112 handle->md.ifindex = -1;
3116 * Select promiscuous mode on if "promisc" is set.
3118 * Do not turn allmulti mode on if we don't select
3119 * promiscuous mode - on some devices (e.g., Orinoco
3120 * wireless interfaces), allmulti mode isn't supported
3121 * and the driver implements it by turning promiscuous
3122 * mode on, and that screws up the operation of the
3123 * card as a normal networking interface, and on no
3124 * other platform I know of does starting a non-
3125 * promiscuous capture affect which multicast packets
3126 * are received by the interface.
3130 * Hmm, how can we set promiscuous mode on all interfaces?
3131 * I am not sure if that is possible at all. For now, we
3132 * silently ignore attempts to turn promiscuous mode on
3133 * for the "any" device (so you don't have to explicitly
3134 * disable it in programs such as tcpdump).
3137 if (!is_any_device && handle->opt.promisc) {
3138 memset(&mr, 0, sizeof(mr));
3139 mr.mr_ifindex = handle->md.ifindex;
3140 mr.mr_type = PACKET_MR_PROMISC;
3141 if (setsockopt(sock_fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP,
3142 &mr, sizeof(mr)) == -1) {
3143 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3144 "setsockopt: %s", pcap_strerror(errno));
3150 /* Enable auxillary data if supported and reserve room for
3151 * reconstructing VLAN headers. */
3152 #ifdef HAVE_PACKET_AUXDATA
3154 if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val,
3155 sizeof(val)) == -1 && errno != ENOPROTOOPT) {
3156 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3157 "setsockopt: %s", pcap_strerror(errno));
3161 handle->offset += VLAN_TAG_LEN;
3162 #endif /* HAVE_PACKET_AUXDATA */
3165 * This is a 2.2[.x] or later kernel (we know that
3166 * because we're not using a SOCK_PACKET socket -
3167 * PF_PACKET is supported only in 2.2 and later
3170 * We can safely pass "recvfrom()" a byte count
3171 * based on the snapshot length.
3173 * If we're in cooked mode, make the snapshot length
3174 * large enough to hold a "cooked mode" header plus
3175 * 1 byte of packet data (so we don't pass a byte
3176 * count of 0 to "recvfrom()").
3178 if (handle->md.cooked) {
3179 if (handle->snapshot < SLL_HDR_LEN + 1)
3180 handle->snapshot = SLL_HDR_LEN + 1;
3182 handle->bufsize = handle->snapshot;
3184 /* Save the socket FD in the pcap structure */
3185 handle->fd = sock_fd;
3190 "New packet capturing interface not supported by build "
3191 "environment", PCAP_ERRBUF_SIZE);
3196 #ifdef HAVE_PACKET_RING
3198 * Attempt to activate with memory-mapped access.
3200 * On success, returns 1, and sets *status to 0 if there are no warnings
3201 * or to a PCAP_WARNING_ code if there is a warning.
3203 * On failure due to lack of support for memory-mapped capture, returns
3206 * On error, returns -1, and sets *status to the appropriate error code;
3207 * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message.
3210 activate_mmap(pcap_t *handle, int *status)
3215 * Attempt to allocate a buffer to hold the contents of one
3216 * packet, for use by the oneshot callback.
3218 handle->md.oneshot_buffer = malloc(handle->snapshot);
3219 if (handle->md.oneshot_buffer == NULL) {
3220 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3221 "can't allocate oneshot buffer: %s",
3222 pcap_strerror(errno));
3223 *status = PCAP_ERROR;
3227 if (handle->opt.buffer_size == 0) {
3228 /* by default request 2M for the ring buffer */
3229 handle->opt.buffer_size = 2*1024*1024;
3231 ret = prepare_tpacket_socket(handle);
3233 free(handle->md.oneshot_buffer);
3234 *status = PCAP_ERROR;
3237 ret = create_ring(handle, status);
3240 * We don't support memory-mapped capture; our caller
3241 * will fall back on reading from the socket.
3243 free(handle->md.oneshot_buffer);
3248 * Error attempting to enable memory-mapped capture;
3249 * fail. create_ring() has set *status.
3251 free(handle->md.oneshot_buffer);
3256 * Success. *status has been set either to 0 if there are no
3257 * warnings or to a PCAP_WARNING_ value if there is a warning.
3259 * Override some defaults and inherit the other fields from
3261 * handle->offset is used to get the current position into the rx ring.
3262 * handle->cc is used to store the ring size.
3264 handle->read_op = pcap_read_linux_mmap;
3265 handle->cleanup_op = pcap_cleanup_linux_mmap;
3266 handle->setfilter_op = pcap_setfilter_linux_mmap;
3267 handle->setnonblock_op = pcap_setnonblock_mmap;
3268 handle->getnonblock_op = pcap_getnonblock_mmap;
3269 handle->oneshot_callback = pcap_oneshot_mmap;
3270 handle->selectable_fd = handle->fd;
3273 #else /* HAVE_PACKET_RING */
3275 activate_mmap(pcap_t *handle _U_, int *status _U_)
3279 #endif /* HAVE_PACKET_RING */
3281 #ifdef HAVE_PACKET_RING
3283 * Attempt to set the socket to version 2 of the memory-mapped header.
3284 * Return 1 if we succeed or if we fail because version 2 isn't
3285 * supported; return -1 on any other error, and set handle->errbuf.
3288 prepare_tpacket_socket(pcap_t *handle)
3290 #ifdef HAVE_TPACKET2
3295 handle->md.tp_version = TPACKET_V1;
3296 handle->md.tp_hdrlen = sizeof(struct tpacket_hdr);
3298 #ifdef HAVE_TPACKET2
3299 /* Probe whether kernel supports TPACKET_V2 */
3302 if (getsockopt(handle->fd, SOL_PACKET, PACKET_HDRLEN, &val, &len) < 0) {
3303 if (errno == ENOPROTOOPT)
3304 return 1; /* no - just drive on */
3306 /* Yes - treat as a failure. */
3307 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3308 "can't get TPACKET_V2 header len on packet socket: %s",
3309 pcap_strerror(errno));
3312 handle->md.tp_hdrlen = val;
3315 if (setsockopt(handle->fd, SOL_PACKET, PACKET_VERSION, &val,
3317 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3318 "can't activate TPACKET_V2 on packet socket: %s",
3319 pcap_strerror(errno));
3322 handle->md.tp_version = TPACKET_V2;
3324 /* Reserve space for VLAN tag reconstruction */
3326 if (setsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &val,
3328 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3329 "can't set up reserve on packet socket: %s",
3330 pcap_strerror(errno));
3334 #endif /* HAVE_TPACKET2 */
3339 * Attempt to set up memory-mapped access.
3341 * On success, returns 1, and sets *status to 0 if there are no warnings
3342 * or to a PCAP_WARNING_ code if there is a warning.
3344 * On failure due to lack of support for memory-mapped capture, returns
3347 * On error, returns -1, and sets *status to the appropriate error code;
3348 * if that is PCAP_ERROR, sets handle->errbuf to the appropriate message.
3351 create_ring(pcap_t *handle, int *status)
3353 unsigned i, j, frames_per_block;
3354 struct tpacket_req req;
3356 unsigned int sk_type, tp_reserve, maclen, tp_hdrlen, netoff, macoff;
3357 unsigned int frame_size;
3360 * Start out assuming no warnings or errors.
3364 /* Note that with large snapshot length (say 64K, which is the default
3365 * for recent versions of tcpdump, the value that "-s 0" has given
3366 * for a long time with tcpdump, and the default in Wireshark/TShark),
3367 * if we use the snapshot length to calculate the frame length,
3368 * only a few frames will be available in the ring even with pretty
3369 * large ring size (and a lot of memory will be unused).
3371 * Ideally, we should choose a frame length based on the
3372 * minimum of the specified snapshot length and the maximum
3373 * packet size. That's not as easy as it sounds; consider, for
3374 * example, an 802.11 interface in monitor mode, where the
3375 * frame would include a radiotap header, where the maximum
3376 * radiotap header length is device-dependent.
3378 * So, for now, we just do this for Ethernet devices, where
3379 * there's no metadata header, and the link-layer header is
3380 * fixed length. We can get the maximum packet size by
3381 * adding 18, the Ethernet header length plus the CRC length
3382 * (just in case we happen to get the CRC in the packet), to
3383 * the MTU of the interface; we fetch the MTU in the hopes
3384 * that it reflects support for jumbo frames. (Even if the
3385 * interface is just being used for passive snooping, the driver
3386 * might set the size of buffers in the receive ring based on
3387 * the MTU, so that the MTU limits the maximum size of packets
3388 * that we can receive.)
3390 * We don't do that if segmentation/fragmentation or receive
3391 * offload are enabled, so we don't get rudely surprised by
3392 * "packets" bigger than the MTU. */
3393 frame_size = handle->snapshot;
3394 if (handle->linktype == DLT_EN10MB) {
3398 offload = iface_get_offload(handle);
3399 if (offload == -1) {
3400 *status = PCAP_ERROR;
3404 mtu = iface_get_mtu(handle->fd, handle->opt.source,
3407 *status = PCAP_ERROR;
3410 if (frame_size > mtu + 18)
3411 frame_size = mtu + 18;
3415 /* NOTE: calculus matching those in tpacket_rcv()
3416 * in linux-2.6/net/packet/af_packet.c
3418 len = sizeof(sk_type);
3419 if (getsockopt(handle->fd, SOL_SOCKET, SO_TYPE, &sk_type, &len) < 0) {
3420 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno));
3421 *status = PCAP_ERROR;
3424 #ifdef PACKET_RESERVE
3425 len = sizeof(tp_reserve);
3426 if (getsockopt(handle->fd, SOL_PACKET, PACKET_RESERVE, &tp_reserve, &len) < 0) {
3427 if (errno != ENOPROTOOPT) {
3429 * ENOPROTOOPT means "kernel doesn't support
3430 * PACKET_RESERVE", in which case we fall back
3433 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "getsockopt: %s", pcap_strerror(errno));
3434 *status = PCAP_ERROR;
3437 tp_reserve = 0; /* older kernel, reserve not supported */
3440 tp_reserve = 0; /* older kernel, reserve not supported */
3442 maclen = (sk_type == SOCK_DGRAM) ? 0 : MAX_LINKHEADER_SIZE;
3443 /* XXX: in the kernel maclen is calculated from
3444 * LL_ALLOCATED_SPACE(dev) and vnet_hdr.hdr_len
3445 * in: packet_snd() in linux-2.6/net/packet/af_packet.c
3446 * then packet_alloc_skb() in linux-2.6/net/packet/af_packet.c
3447 * then sock_alloc_send_pskb() in linux-2.6/net/core/sock.c
3448 * but I see no way to get those sizes in userspace,
3449 * like for instance with an ifreq ioctl();
3450 * the best thing I've found so far is MAX_HEADER in the kernel
3451 * part of linux-2.6/include/linux/netdevice.h
3452 * which goes up to 128+48=176; since pcap-linux.c defines
3453 * a MAX_LINKHEADER_SIZE of 256 which is greater than that,
3454 * let's use it.. maybe is it even large enough to directly
3457 tp_hdrlen = TPACKET_ALIGN(handle->md.tp_hdrlen) + sizeof(struct sockaddr_ll) ;
3458 netoff = TPACKET_ALIGN(tp_hdrlen + (maclen < 16 ? 16 : maclen)) + tp_reserve;
3459 /* NOTE: AFAICS tp_reserve may break the TPACKET_ALIGN of
3460 * netoff, which contradicts
3461 * linux-2.6/Documentation/networking/packet_mmap.txt
3463 * "- Gap, chosen so that packet data (Start+tp_net)
3464 * aligns to TPACKET_ALIGNMENT=16"
3466 /* NOTE: in linux-2.6/include/linux/skbuff.h:
3467 * "CPUs often take a performance hit
3468 * when accessing unaligned memory locations"
3470 macoff = netoff - maclen;
3471 req.tp_frame_size = TPACKET_ALIGN(macoff + frame_size);
3472 req.tp_frame_nr = handle->opt.buffer_size/req.tp_frame_size;
3474 /* compute the minumum block size that will handle this frame.
3475 * The block has to be page size aligned.
3476 * The max block size allowed by the kernel is arch-dependent and
3477 * it's not explicitly checked here. */
3478 req.tp_block_size = getpagesize();
3479 while (req.tp_block_size < req.tp_frame_size)
3480 req.tp_block_size <<= 1;
3482 frames_per_block = req.tp_block_size/req.tp_frame_size;
3485 * PACKET_TIMESTAMP was added after linux/net_tstamp.h was,
3486 * so we check for PACKET_TIMESTAMP. We check for
3487 * linux/net_tstamp.h just in case a system somehow has
3488 * PACKET_TIMESTAMP but not linux/net_tstamp.h; that might
3491 * SIOCSHWTSTAMP was introduced in the patch that introduced
3492 * linux/net_tstamp.h, so we don't bother checking whether
3493 * SIOCSHWTSTAMP is defined (if your Linux system has
3494 * linux/net_tstamp.h but doesn't define SIOCSHWTSTAMP, your
3495 * Linux system is badly broken).
3497 #if defined(HAVE_LINUX_NET_TSTAMP_H) && defined(PACKET_TIMESTAMP)
3499 * If we were told to do so, ask the kernel and the driver
3500 * to use hardware timestamps.
3502 * Hardware timestamps are only supported with mmapped
3505 if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER ||
3506 handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER_UNSYNCED) {
3507 struct hwtstamp_config hwconfig;
3512 * Ask for hardware time stamps on all packets,
3513 * including transmitted packets.
3515 memset(&hwconfig, 0, sizeof(hwconfig));
3516 hwconfig.tx_type = HWTSTAMP_TX_ON;
3517 hwconfig.rx_filter = HWTSTAMP_FILTER_ALL;
3519 memset(&ifr, 0, sizeof(ifr));
3520 strcpy(ifr.ifr_name, handle->opt.source);
3521 ifr.ifr_data = (void *)&hwconfig;
3523 if (ioctl(handle->fd, SIOCSHWTSTAMP, &ifr) < 0) {
3528 * Treat this as an error, as the
3529 * user should try to run this
3530 * with the appropriate privileges -
3531 * and, if they can't, shouldn't
3532 * try requesting hardware time stamps.
3534 *status = PCAP_ERROR_PERM_DENIED;
3539 * Treat this as a warning, as the
3540 * only way to fix the warning is to
3541 * get an adapter that supports hardware
3542 * time stamps. We'll just fall back
3543 * on the standard host time stamps.
3545 *status = PCAP_WARNING_TSTAMP_TYPE_NOTSUP;
3549 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3550 "SIOCSHWTSTAMP failed: %s",
3551 pcap_strerror(errno));
3552 *status = PCAP_ERROR;
3557 * Well, that worked. Now specify the type of
3558 * hardware time stamp we want for this
3561 if (handle->opt.tstamp_type == PCAP_TSTAMP_ADAPTER) {
3563 * Hardware timestamp, synchronized
3564 * with the system clock.
3566 timesource = SOF_TIMESTAMPING_SYS_HARDWARE;
3569 * PCAP_TSTAMP_ADAPTER_UNSYNCED - hardware
3570 * timestamp, not synchronized with the
3573 timesource = SOF_TIMESTAMPING_RAW_HARDWARE;
3575 if (setsockopt(handle->fd, SOL_PACKET, PACKET_TIMESTAMP,
3576 (void *)×ource, sizeof(timesource))) {
3577 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3578 "can't set PACKET_TIMESTAMP: %s",
3579 pcap_strerror(errno));
3580 *status = PCAP_ERROR;
3585 #endif /* HAVE_LINUX_NET_TSTAMP_H && PACKET_TIMESTAMP */
3587 /* ask the kernel to create the ring */
3589 req.tp_block_nr = req.tp_frame_nr / frames_per_block;
3591 /* req.tp_frame_nr is requested to match frames_per_block*req.tp_block_nr */
3592 req.tp_frame_nr = req.tp_block_nr * frames_per_block;
3594 if (setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
3595 (void *) &req, sizeof(req))) {
3596 if ((errno == ENOMEM) && (req.tp_block_nr > 1)) {
3598 * Memory failure; try to reduce the requested ring
3601 * We used to reduce this by half -- do 5% instead.
3602 * That may result in more iterations and a longer
3603 * startup, but the user will be much happier with
3604 * the resulting buffer size.
3606 if (req.tp_frame_nr < 20)
3607 req.tp_frame_nr -= 1;
3609 req.tp_frame_nr -= req.tp_frame_nr/20;
3612 if (errno == ENOPROTOOPT) {
3614 * We don't have ring buffer support in this kernel.
3618 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3619 "can't create rx ring on packet socket: %s",
3620 pcap_strerror(errno));
3621 *status = PCAP_ERROR;
3625 /* memory map the rx ring */
3626 handle->md.mmapbuflen = req.tp_block_nr * req.tp_block_size;
3627 handle->md.mmapbuf = mmap(0, handle->md.mmapbuflen,
3628 PROT_READ|PROT_WRITE, MAP_SHARED, handle->fd, 0);
3629 if (handle->md.mmapbuf == MAP_FAILED) {
3630 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3631 "can't mmap rx ring: %s", pcap_strerror(errno));
3633 /* clear the allocated ring on error*/
3634 destroy_ring(handle);
3635 *status = PCAP_ERROR;
3639 /* allocate a ring for each frame header pointer*/
3640 handle->cc = req.tp_frame_nr;
3641 handle->buffer = malloc(handle->cc * sizeof(union thdr *));
3642 if (!handle->buffer) {
3643 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3644 "can't allocate ring of frame headers: %s",
3645 pcap_strerror(errno));
3647 destroy_ring(handle);
3648 *status = PCAP_ERROR;
3652 /* fill the header ring with proper frame ptr*/
3654 for (i=0; i<req.tp_block_nr; ++i) {
3655 void *base = &handle->md.mmapbuf[i*req.tp_block_size];
3656 for (j=0; j<frames_per_block; ++j, ++handle->offset) {
3657 RING_GET_FRAME(handle) = base;
3658 base += req.tp_frame_size;
3662 handle->bufsize = req.tp_frame_size;
3667 /* free all ring related resources*/
3669 destroy_ring(pcap_t *handle)
3671 /* tell the kernel to destroy the ring*/
3672 struct tpacket_req req;
3673 memset(&req, 0, sizeof(req));
3674 setsockopt(handle->fd, SOL_PACKET, PACKET_RX_RING,
3675 (void *) &req, sizeof(req));
3677 /* if ring is mapped, unmap it*/
3678 if (handle->md.mmapbuf) {
3679 /* do not test for mmap failure, as we can't recover from any error */
3680 munmap(handle->md.mmapbuf, handle->md.mmapbuflen);
3681 handle->md.mmapbuf = NULL;
3686 * Special one-shot callback, used for pcap_next() and pcap_next_ex(),
3687 * for Linux mmapped capture.
3689 * The problem is that pcap_next() and pcap_next_ex() expect the packet
3690 * data handed to the callback to be valid after the callback returns,
3691 * but pcap_read_linux_mmap() has to release that packet as soon as
3692 * the callback returns (otherwise, the kernel thinks there's still
3693 * at least one unprocessed packet available in the ring, so a select()
3694 * will immediately return indicating that there's data to process), so,
3695 * in the callback, we have to make a copy of the packet.
3697 * Yes, this means that, if the capture is using the ring buffer, using
3698 * pcap_next() or pcap_next_ex() requires more copies than using
3699 * pcap_loop() or pcap_dispatch(). If that bothers you, don't use
3700 * pcap_next() or pcap_next_ex().
3703 pcap_oneshot_mmap(u_char *user, const struct pcap_pkthdr *h,
3704 const u_char *bytes)
3706 struct oneshot_userdata *sp = (struct oneshot_userdata *)user;
3709 memcpy(sp->pd->md.oneshot_buffer, bytes, h->caplen);
3710 *sp->pkt = sp->pd->md.oneshot_buffer;
3714 pcap_cleanup_linux_mmap( pcap_t *handle )
3716 destroy_ring(handle);
3717 if (handle->md.oneshot_buffer != NULL) {
3718 free(handle->md.oneshot_buffer);
3719 handle->md.oneshot_buffer = NULL;
3721 pcap_cleanup_linux(handle);
3726 pcap_getnonblock_mmap(pcap_t *p, char *errbuf)
3728 /* use negative value of timeout to indicate non blocking ops */
3729 return (p->md.timeout<0);
3733 pcap_setnonblock_mmap(pcap_t *p, int nonblock, char *errbuf)
3735 /* map each value to the corresponding 2's complement, to
3736 * preserve the timeout value provided with pcap_set_timeout */
3738 if (p->md.timeout >= 0) {
3740 * Timeout is non-negative, so we're not already
3741 * in non-blocking mode; set it to the 2's
3742 * complement, to make it negative, as an
3743 * indication that we're in non-blocking mode.
3745 p->md.timeout = p->md.timeout*-1 - 1;
3748 if (p->md.timeout < 0) {
3750 * Timeout is negative, so we're not already
3751 * in blocking mode; reverse the previous
3752 * operation, to make the timeout non-negative
3755 p->md.timeout = (p->md.timeout+1)*-1;
3761 static inline union thdr *
3762 pcap_get_ring_frame(pcap_t *handle, int status)
3766 h.raw = RING_GET_FRAME(handle);
3767 switch (handle->md.tp_version) {
3769 if (status != (h.h1->tp_status ? TP_STATUS_USER :
3773 #ifdef HAVE_TPACKET2
3775 if (status != (h.h2->tp_status ? TP_STATUS_USER :
3789 pcap_read_linux_mmap(pcap_t *handle, int max_packets, pcap_handler callback,
3796 /* wait for frames availability.*/
3797 if (!pcap_get_ring_frame(handle, TP_STATUS_USER)) {
3798 struct pollfd pollinfo;
3801 pollinfo.fd = handle->fd;
3802 pollinfo.events = POLLIN;
3804 if (handle->md.timeout == 0)
3805 timeout = -1; /* block forever */
3806 else if (handle->md.timeout > 0)
3807 timeout = handle->md.timeout; /* block for that amount of time */
3809 timeout = 0; /* non-blocking mode - poll to pick up errors */
3811 ret = poll(&pollinfo, 1, timeout);
3812 if (ret < 0 && errno != EINTR) {
3813 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3814 "can't poll on packet socket: %s",
3815 pcap_strerror(errno));
3817 } else if (ret > 0 &&
3818 (pollinfo.revents & (POLLHUP|POLLRDHUP|POLLERR|POLLNVAL))) {
3820 * There's some indication other than
3821 * "you can read on this descriptor" on
3824 if (pollinfo.revents & (POLLHUP | POLLRDHUP)) {
3825 snprintf(handle->errbuf,
3827 "Hangup on packet socket");
3830 if (pollinfo.revents & POLLERR) {
3832 * A recv() will give us the
3833 * actual error code.
3835 * XXX - make the socket non-blocking?
3837 if (recv(handle->fd, &c, sizeof c,
3839 continue; /* what, no error? */
3840 if (errno == ENETDOWN) {
3842 * The device on which we're
3843 * capturing went away.
3845 * XXX - we should really return
3846 * PCAP_ERROR_IFACE_NOT_UP,
3847 * but pcap_dispatch() etc.
3848 * aren't defined to return
3851 snprintf(handle->errbuf,
3853 "The interface went down");
3855 snprintf(handle->errbuf,
3857 "Error condition on packet socket: %s",
3862 if (pollinfo.revents & POLLNVAL) {
3863 snprintf(handle->errbuf,
3865 "Invalid polling request on packet socket");
3869 /* check for break loop condition on interrupted syscall*/
3870 if (handle->break_loop) {
3871 handle->break_loop = 0;
3872 return PCAP_ERROR_BREAK;
3877 /* non-positive values of max_packets are used to require all
3878 * packets currently available in the ring */
3879 while ((pkts < max_packets) || (max_packets <= 0)) {
3881 struct sockaddr_ll *sll;
3882 struct pcap_pkthdr pcaphdr;
3885 unsigned int tp_len;
3886 unsigned int tp_mac;
3887 unsigned int tp_snaplen;
3888 unsigned int tp_sec;
3889 unsigned int tp_usec;
3891 h.raw = pcap_get_ring_frame(handle, TP_STATUS_USER);
3895 switch (handle->md.tp_version) {
3897 tp_len = h.h1->tp_len;
3898 tp_mac = h.h1->tp_mac;
3899 tp_snaplen = h.h1->tp_snaplen;
3900 tp_sec = h.h1->tp_sec;
3901 tp_usec = h.h1->tp_usec;
3903 #ifdef HAVE_TPACKET2
3905 tp_len = h.h2->tp_len;
3906 tp_mac = h.h2->tp_mac;
3907 tp_snaplen = h.h2->tp_snaplen;
3908 tp_sec = h.h2->tp_sec;
3909 tp_usec = h.h2->tp_nsec / 1000;
3913 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3914 "unsupported tpacket version %d",
3915 handle->md.tp_version);
3918 /* perform sanity check on internal offset. */
3919 if (tp_mac + tp_snaplen > handle->bufsize) {
3920 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
3921 "corrupted frame on kernel ring mac "
3922 "offset %d + caplen %d > frame len %d",
3923 tp_mac, tp_snaplen, handle->bufsize);
3927 /* run filter on received packet
3928 * If the kernel filtering is enabled we need to run the
3929 * filter until all the frames present into the ring
3930 * at filter creation time are processed.
3931 * In such case md.use_bpf is used as a counter for the
3932 * packet we need to filter.
3933 * Note: alternatively it could be possible to stop applying
3934 * the filter when the ring became empty, but it can possibly
3935 * happen a lot later... */
3936 bp = (unsigned char*)h.raw + tp_mac;
3937 run_bpf = (!handle->md.use_bpf) ||
3938 ((handle->md.use_bpf>1) && handle->md.use_bpf--);
3939 if (run_bpf && handle->fcode.bf_insns &&
3940 (bpf_filter(handle->fcode.bf_insns, bp,
3941 tp_len, tp_snaplen) == 0))
3945 * Do checks based on packet direction.
3947 sll = (void *)h.raw + TPACKET_ALIGN(handle->md.tp_hdrlen);
3948 if (sll->sll_pkttype == PACKET_OUTGOING) {
3951 * If this is from the loopback device, reject it;
3952 * we'll see the packet as an incoming packet as well,
3953 * and we don't want to see it twice.
3955 if (sll->sll_ifindex == handle->md.lo_ifindex)
3959 * If the user only wants incoming packets, reject it.
3961 if (handle->direction == PCAP_D_IN)
3966 * If the user only wants outgoing packets, reject it.
3968 if (handle->direction == PCAP_D_OUT)
3972 /* get required packet info from ring header */
3973 pcaphdr.ts.tv_sec = tp_sec;
3974 pcaphdr.ts.tv_usec = tp_usec;
3975 pcaphdr.caplen = tp_snaplen;
3976 pcaphdr.len = tp_len;
3978 /* if required build in place the sll header*/
3979 if (handle->md.cooked) {
3980 struct sll_header *hdrp;
3983 * The kernel should have left us with enough
3984 * space for an sll header; back up the packet
3985 * data pointer into that space, as that'll be
3986 * the beginning of the packet we pass to the
3992 * Let's make sure that's past the end of
3993 * the tpacket header, i.e. >=
3994 * ((u_char *)thdr + TPACKET_HDRLEN), so we
3995 * don't step on the header when we construct
3998 if (bp < (u_char *)h.raw +
3999 TPACKET_ALIGN(handle->md.tp_hdrlen) +
4000 sizeof(struct sockaddr_ll)) {
4001 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4002 "cooked-mode frame doesn't have room for sll header");
4007 * OK, that worked; construct the sll header.
4009 hdrp = (struct sll_header *)bp;
4010 hdrp->sll_pkttype = map_packet_type_to_sll_type(
4012 hdrp->sll_hatype = htons(sll->sll_hatype);
4013 hdrp->sll_halen = htons(sll->sll_halen);
4014 memcpy(hdrp->sll_addr, sll->sll_addr, SLL_ADDRLEN);
4015 hdrp->sll_protocol = sll->sll_protocol;
4017 /* update packet len */
4018 pcaphdr.caplen += SLL_HDR_LEN;
4019 pcaphdr.len += SLL_HDR_LEN;
4022 #ifdef HAVE_TPACKET2
4023 if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci &&
4024 tp_snaplen >= 2 * ETH_ALEN) {
4025 struct vlan_tag *tag;
4028 memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN);
4030 tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN);
4031 tag->vlan_tpid = htons(ETH_P_8021Q);
4032 tag->vlan_tci = htons(h.h2->tp_vlan_tci);
4034 pcaphdr.caplen += VLAN_TAG_LEN;
4035 pcaphdr.len += VLAN_TAG_LEN;
4040 * The only way to tell the kernel to cut off the
4041 * packet at a snapshot length is with a filter program;
4042 * if there's no filter program, the kernel won't cut
4045 * Trim the snapshot length to be no longer than the
4046 * specified snapshot length.
4048 if (pcaphdr.caplen > handle->snapshot)
4049 pcaphdr.caplen = handle->snapshot;
4051 /* pass the packet to the user */
4053 callback(user, &pcaphdr, bp);
4054 handle->md.packets_read++;
4058 switch (handle->md.tp_version) {
4060 h.h1->tp_status = TP_STATUS_KERNEL;
4062 #ifdef HAVE_TPACKET2
4064 h.h2->tp_status = TP_STATUS_KERNEL;
4068 if (++handle->offset >= handle->cc)
4071 /* check for break loop condition*/
4072 if (handle->break_loop) {
4073 handle->break_loop = 0;
4074 return PCAP_ERROR_BREAK;
4081 pcap_setfilter_linux_mmap(pcap_t *handle, struct bpf_program *filter)
4087 * Don't rewrite "ret" instructions; we don't need to, as
4088 * we're not reading packets with recvmsg(), and we don't
4089 * want to, as, by not rewriting them, the kernel can avoid
4090 * copying extra data.
4092 ret = pcap_setfilter_linux_common(handle, filter, 1);
4096 /* if the kernel filter is enabled, we need to apply the filter on
4097 * all packets present into the ring. Get an upper bound of their number
4099 if (!handle->md.use_bpf)
4102 /* walk the ring backward and count the free slot */
4103 offset = handle->offset;
4104 if (--handle->offset < 0)
4105 handle->offset = handle->cc - 1;
4106 for (n=0; n < handle->cc; ++n) {
4107 if (--handle->offset < 0)
4108 handle->offset = handle->cc - 1;
4109 if (!pcap_get_ring_frame(handle, TP_STATUS_KERNEL))
4113 /* be careful to not change current ring position */
4114 handle->offset = offset;
4116 /* store the number of packets currently present in the ring */
4117 handle->md.use_bpf = 1 + (handle->cc - n);
4121 #endif /* HAVE_PACKET_RING */
4124 #ifdef HAVE_PF_PACKET_SOCKETS
4126 * Return the index of the given device name. Fill ebuf and return
4130 iface_get_id(int fd, const char *device, char *ebuf)
4134 memset(&ifr, 0, sizeof(ifr));
4135 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
4137 if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
4138 snprintf(ebuf, PCAP_ERRBUF_SIZE,
4139 "SIOCGIFINDEX: %s", pcap_strerror(errno));
4143 return ifr.ifr_ifindex;
4147 * Bind the socket associated with FD to the given device.
4148 * Return 1 on success, 0 if we should try a SOCK_PACKET socket,
4149 * or a PCAP_ERROR_ value on a hard error.
4152 iface_bind(int fd, int ifindex, char *ebuf)
4154 struct sockaddr_ll sll;
4156 socklen_t errlen = sizeof(err);
4158 memset(&sll, 0, sizeof(sll));
4159 sll.sll_family = AF_PACKET;
4160 sll.sll_ifindex = ifindex;
4161 sll.sll_protocol = htons(ETH_P_ALL);
4163 if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
4164 if (errno == ENETDOWN) {
4166 * Return a "network down" indication, so that
4167 * the application can report that rather than
4168 * saying we had a mysterious failure and
4169 * suggest that they report a problem to the
4170 * libpcap developers.
4172 return PCAP_ERROR_IFACE_NOT_UP;
4174 snprintf(ebuf, PCAP_ERRBUF_SIZE,
4175 "bind: %s", pcap_strerror(errno));
4180 /* Any pending errors, e.g., network is down? */
4182 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
4183 snprintf(ebuf, PCAP_ERRBUF_SIZE,
4184 "getsockopt: %s", pcap_strerror(errno));
4188 if (err == ENETDOWN) {
4190 * Return a "network down" indication, so that
4191 * the application can report that rather than
4192 * saying we had a mysterious failure and
4193 * suggest that they report a problem to the
4194 * libpcap developers.
4196 return PCAP_ERROR_IFACE_NOT_UP;
4197 } else if (err > 0) {
4198 snprintf(ebuf, PCAP_ERRBUF_SIZE,
4199 "bind: %s", pcap_strerror(err));
4206 #ifdef IW_MODE_MONITOR
4208 * Check whether the device supports the Wireless Extensions.
4209 * Returns 1 if it does, 0 if it doesn't, PCAP_ERROR_NO_SUCH_DEVICE
4210 * if the device doesn't even exist.
4213 has_wext(int sock_fd, const char *device, char *ebuf)
4217 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4218 sizeof ireq.ifr_ifrn.ifrn_name);
4219 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4220 if (ioctl(sock_fd, SIOCGIWNAME, &ireq) >= 0)
4222 snprintf(ebuf, PCAP_ERRBUF_SIZE,
4223 "%s: SIOCGIWPRIV: %s", device, pcap_strerror(errno));
4224 if (errno == ENODEV)
4225 return PCAP_ERROR_NO_SUCH_DEVICE;
4230 * Per me si va ne la citta dolente,
4231 * Per me si va ne l'etterno dolore,
4233 * Lasciate ogne speranza, voi ch'intrate.
4235 * XXX - airmon-ng does special stuff with the Orinoco driver and the
4251 * Use the Wireless Extensions, if we have them, to try to turn monitor mode
4252 * on if it's not already on.
4254 * Returns 1 on success, 0 if we don't support the Wireless Extensions
4255 * on this device, or a PCAP_ERROR_ value if we do support them but
4256 * we weren't able to turn monitor mode on.
4259 enter_rfmon_mode_wext(pcap_t *handle, int sock_fd, const char *device)
4262 * XXX - at least some adapters require non-Wireless Extensions
4263 * mechanisms to turn monitor mode on.
4265 * Atheros cards might require that a separate "monitor virtual access
4266 * point" be created, with later versions of the madwifi driver.
4267 * airmon-ng does "wlanconfig ath create wlandev {if} wlanmode
4268 * monitor -bssid", which apparently spits out a line "athN"
4269 * where "athN" is the monitor mode device. To leave monitor
4270 * mode, it destroys the monitor mode device.
4272 * Some Intel Centrino adapters might require private ioctls to get
4273 * radio headers; the ipw2200 and ipw3945 drivers allow you to
4274 * configure a separate "rtapN" interface to capture in monitor
4275 * mode without preventing the adapter from operating normally.
4276 * (airmon-ng doesn't appear to use that, though.)
4278 * It would be Truly Wonderful if mac80211 and nl80211 cleaned this
4279 * up, and if all drivers were converted to mac80211 drivers.
4281 * If interface {if} is a mac80211 driver, the file
4282 * /sys/class/net/{if}/phy80211 is a symlink to
4283 * /sys/class/ieee80211/{phydev}, for some {phydev}.
4285 * On Fedora 9, with a 2.6.26.3-29 kernel, my Zydas stick, at
4286 * least, has a "wmaster0" device and a "wlan0" device; the
4287 * latter is the one with the IP address. Both show up in
4288 * "tcpdump -D" output. Capturing on the wmaster0 device
4289 * captures with 802.11 headers.
4291 * airmon-ng searches through /sys/class/net for devices named
4292 * monN, starting with mon0; as soon as one *doesn't* exist,
4293 * it chooses that as the monitor device name. If the "iw"
4294 * command exists, it does "iw dev {if} interface add {monif}
4295 * type monitor", where {monif} is the monitor device. It
4296 * then (sigh) sleeps .1 second, and then configures the
4297 * device up. Otherwise, if /sys/class/ieee80211/{phydev}/add_iface
4298 * is a file, it writes {mondev}, without a newline, to that file,
4299 * and again (sigh) sleeps .1 second, and then iwconfig's that
4300 * device into monitor mode and configures it up. Otherwise,
4301 * you can't do monitor mode.
4303 * All these devices are "glued" together by having the
4304 * /sys/class/net/{device}/phy80211 links pointing to the same
4305 * place, so, given a wmaster, wlan, or mon device, you can
4306 * find the other devices by looking for devices with
4307 * the same phy80211 link.
4309 * To turn monitor mode off, delete the monitor interface,
4310 * either with "iw dev {monif} interface del" or by sending
4311 * {monif}, with no NL, down /sys/class/ieee80211/{phydev}/remove_iface
4313 * Note: if you try to create a monitor device named "monN", and
4314 * there's already a "monN" device, it fails, as least with
4315 * the netlink interface (which is what iw uses), with a return
4316 * value of -ENFILE. (Return values are negative errnos.) We
4317 * could probably use that to find an unused device.
4321 struct iw_priv_args *priv;
4322 monitor_type montype;
4331 * Does this device *support* the Wireless Extensions?
4333 err = has_wext(sock_fd, device, handle->errbuf);
4335 return err; /* either it doesn't or the device doesn't even exist */
4337 * Start out assuming we have no private extensions to control
4340 montype = MONITOR_WEXT;
4344 * Try to get all the Wireless Extensions private ioctls
4345 * supported by this device.
4347 * First, get the size of the buffer we need, by supplying no
4348 * buffer and a length of 0. If the device supports private
4349 * ioctls, it should return E2BIG, with ireq.u.data.length set
4350 * to the length we need. If it doesn't support them, it should
4351 * return EOPNOTSUPP.
4353 memset(&ireq, 0, sizeof ireq);
4354 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4355 sizeof ireq.ifr_ifrn.ifrn_name);
4356 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4357 ireq.u.data.pointer = (void *)args;
4358 ireq.u.data.length = 0;
4359 ireq.u.data.flags = 0;
4360 if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) != -1) {
4361 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4362 "%s: SIOCGIWPRIV with a zero-length buffer didn't fail!",
4366 if (errno != EOPNOTSUPP) {
4368 * OK, it's not as if there are no private ioctls.
4370 if (errno != E2BIG) {
4374 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4375 "%s: SIOCGIWPRIV: %s", device,
4376 pcap_strerror(errno));
4381 * OK, try to get the list of private ioctls.
4383 priv = malloc(ireq.u.data.length * sizeof (struct iw_priv_args));
4385 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4386 "malloc: %s", pcap_strerror(errno));
4389 ireq.u.data.pointer = (void *)priv;
4390 if (ioctl(sock_fd, SIOCGIWPRIV, &ireq) == -1) {
4391 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4392 "%s: SIOCGIWPRIV: %s", device,
4393 pcap_strerror(errno));
4399 * Look for private ioctls to turn monitor mode on or, if
4400 * monitor mode is on, to set the header type.
4402 for (i = 0; i < ireq.u.data.length; i++) {
4403 if (strcmp(priv[i].name, "monitor_type") == 0) {
4405 * Hostap driver, use this one.
4406 * Set monitor mode first.
4407 * You can set it to 0 to get DLT_IEEE80211,
4408 * 1 to get DLT_PRISM, 2 to get
4409 * DLT_IEEE80211_RADIO_AVS, and, with more
4410 * recent versions of the driver, 3 to get
4411 * DLT_IEEE80211_RADIO.
4413 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
4415 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
4417 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
4419 montype = MONITOR_HOSTAP;
4423 if (strcmp(priv[i].name, "set_prismhdr") == 0) {
4425 * Prism54 driver, use this one.
4426 * Set monitor mode first.
4427 * You can set it to 2 to get DLT_IEEE80211
4428 * or 3 or get DLT_PRISM.
4430 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
4432 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
4434 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
4436 montype = MONITOR_PRISM54;
4440 if (strcmp(priv[i].name, "forceprismheader") == 0) {
4442 * RT2570 driver, use this one.
4443 * Do this after turning monitor mode on.
4444 * You can set it to 1 to get DLT_PRISM or 2
4445 * to get DLT_IEEE80211.
4447 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
4449 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
4451 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
4453 montype = MONITOR_RT2570;
4457 if (strcmp(priv[i].name, "forceprism") == 0) {
4459 * RT73 driver, use this one.
4460 * Do this after turning monitor mode on.
4461 * Its argument is a *string*; you can
4462 * set it to "1" to get DLT_PRISM or "2"
4463 * to get DLT_IEEE80211.
4465 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_CHAR)
4467 if (priv[i].set_args & IW_PRIV_SIZE_FIXED)
4469 montype = MONITOR_RT73;
4473 if (strcmp(priv[i].name, "prismhdr") == 0) {
4475 * One of the RTL8xxx drivers, use this one.
4476 * It can only be done after monitor mode
4477 * has been turned on. You can set it to 1
4478 * to get DLT_PRISM or 0 to get DLT_IEEE80211.
4480 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
4482 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
4484 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 1)
4486 montype = MONITOR_RTL8XXX;
4490 if (strcmp(priv[i].name, "rfmontx") == 0) {
4492 * RT2500 or RT61 driver, use this one.
4493 * It has one one-byte parameter; set
4494 * u.data.length to 1 and u.data.pointer to
4495 * point to the parameter.
4496 * It doesn't itself turn monitor mode on.
4497 * You can set it to 1 to allow transmitting
4498 * in monitor mode(?) and get DLT_IEEE80211,
4499 * or set it to 0 to disallow transmitting in
4500 * monitor mode(?) and get DLT_PRISM.
4502 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
4504 if ((priv[i].set_args & IW_PRIV_SIZE_MASK) != 2)
4506 montype = MONITOR_RT2500;
4510 if (strcmp(priv[i].name, "monitor") == 0) {
4512 * Either ACX100 or hostap, use this one.
4513 * It turns monitor mode on.
4514 * If it takes two arguments, it's ACX100;
4515 * the first argument is 1 for DLT_PRISM
4516 * or 2 for DLT_IEEE80211, and the second
4517 * argument is the channel on which to
4518 * run. If it takes one argument, it's
4519 * HostAP, and the argument is 2 for
4520 * DLT_IEEE80211 and 3 for DLT_PRISM.
4522 * If we see this, we don't quit, as this
4523 * might be a version of the hostap driver
4524 * that also supports "monitor_type".
4526 if ((priv[i].set_args & IW_PRIV_TYPE_MASK) != IW_PRIV_TYPE_INT)
4528 if (!(priv[i].set_args & IW_PRIV_SIZE_FIXED))
4530 switch (priv[i].set_args & IW_PRIV_SIZE_MASK) {
4533 montype = MONITOR_PRISM;
4538 montype = MONITOR_ACX100;
4551 * XXX - ipw3945? islism?
4557 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4558 sizeof ireq.ifr_ifrn.ifrn_name);
4559 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4560 if (ioctl(sock_fd, SIOCGIWMODE, &ireq) == -1) {
4562 * We probably won't be able to set the mode, either.
4564 return PCAP_ERROR_RFMON_NOTSUP;
4568 * Is it currently in monitor mode?
4570 if (ireq.u.mode == IW_MODE_MONITOR) {
4572 * Yes. Just leave things as they are.
4573 * We don't offer multiple link-layer types, as
4574 * changing the link-layer type out from under
4575 * somebody else capturing in monitor mode would
4576 * be considered rude.
4581 * No. We have to put the adapter into rfmon mode.
4585 * If we haven't already done so, arrange to have
4586 * "pcap_close_all()" called when we exit.
4588 if (!pcap_do_addexit(handle)) {
4590 * "atexit()" failed; don't put the interface
4591 * in rfmon mode, just give up.
4593 return PCAP_ERROR_RFMON_NOTSUP;
4597 * Save the old mode.
4599 handle->md.oldmode = ireq.u.mode;
4602 * Put the adapter in rfmon mode. How we do this depends
4603 * on whether we have a special private ioctl or not.
4605 if (montype == MONITOR_PRISM) {
4607 * We have the "monitor" private ioctl, but none of
4608 * the other private ioctls. Use this, and select
4611 * If it fails, just fall back on SIOCSIWMODE.
4613 memset(&ireq, 0, sizeof ireq);
4614 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4615 sizeof ireq.ifr_ifrn.ifrn_name);
4616 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4617 ireq.u.data.length = 1; /* 1 argument */
4618 args[0] = 3; /* request Prism header */
4619 memcpy(ireq.u.name, args, IFNAMSIZ);
4620 if (ioctl(sock_fd, cmd, &ireq) != -1) {
4623 * Note that we have to put the old mode back
4624 * when we close the device.
4626 handle->md.must_do_on_close |= MUST_CLEAR_RFMON;
4629 * Add this to the list of pcaps to close
4632 pcap_add_to_pcaps_to_close(handle);
4638 * Failure. Fall back on SIOCSIWMODE.
4643 * First, take the interface down if it's up; otherwise, we
4646 memset(&ifr, 0, sizeof(ifr));
4647 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
4648 if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
4649 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4650 "%s: Can't get flags: %s", device, strerror(errno));
4654 if (ifr.ifr_flags & IFF_UP) {
4655 oldflags = ifr.ifr_flags;
4656 ifr.ifr_flags &= ~IFF_UP;
4657 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
4658 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4659 "%s: Can't set flags: %s", device, strerror(errno));
4665 * Then turn monitor mode on.
4667 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4668 sizeof ireq.ifr_ifrn.ifrn_name);
4669 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4670 ireq.u.mode = IW_MODE_MONITOR;
4671 if (ioctl(sock_fd, SIOCSIWMODE, &ireq) == -1) {
4673 * Scientist, you've failed.
4674 * Bring the interface back up if we shut it down.
4676 ifr.ifr_flags = oldflags;
4677 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
4678 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4679 "%s: Can't set flags: %s", device, strerror(errno));
4682 return PCAP_ERROR_RFMON_NOTSUP;
4686 * XXX - airmon-ng does "iwconfig {if} key off" after setting
4687 * monitor mode and setting the channel, and then does
4692 * Now select the appropriate radio header.
4698 * We don't have any private ioctl to set the header.
4702 case MONITOR_HOSTAP:
4704 * Try to select the radiotap header.
4706 memset(&ireq, 0, sizeof ireq);
4707 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4708 sizeof ireq.ifr_ifrn.ifrn_name);
4709 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4710 args[0] = 3; /* request radiotap header */
4711 memcpy(ireq.u.name, args, sizeof (int));
4712 if (ioctl(sock_fd, cmd, &ireq) != -1)
4713 break; /* success */
4716 * That failed. Try to select the AVS header.
4718 memset(&ireq, 0, sizeof ireq);
4719 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4720 sizeof ireq.ifr_ifrn.ifrn_name);
4721 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4722 args[0] = 2; /* request AVS header */
4723 memcpy(ireq.u.name, args, sizeof (int));
4724 if (ioctl(sock_fd, cmd, &ireq) != -1)
4725 break; /* success */
4728 * That failed. Try to select the Prism header.
4730 memset(&ireq, 0, sizeof ireq);
4731 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4732 sizeof ireq.ifr_ifrn.ifrn_name);
4733 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4734 args[0] = 1; /* request Prism header */
4735 memcpy(ireq.u.name, args, sizeof (int));
4736 ioctl(sock_fd, cmd, &ireq);
4741 * The private ioctl failed.
4745 case MONITOR_PRISM54:
4747 * Select the Prism header.
4749 memset(&ireq, 0, sizeof ireq);
4750 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4751 sizeof ireq.ifr_ifrn.ifrn_name);
4752 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4753 args[0] = 3; /* request Prism header */
4754 memcpy(ireq.u.name, args, sizeof (int));
4755 ioctl(sock_fd, cmd, &ireq);
4758 case MONITOR_ACX100:
4760 * Get the current channel.
4762 memset(&ireq, 0, sizeof ireq);
4763 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4764 sizeof ireq.ifr_ifrn.ifrn_name);
4765 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4766 if (ioctl(sock_fd, SIOCGIWFREQ, &ireq) == -1) {
4767 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4768 "%s: SIOCGIWFREQ: %s", device,
4769 pcap_strerror(errno));
4772 channel = ireq.u.freq.m;
4775 * Select the Prism header, and set the channel to the
4778 memset(&ireq, 0, sizeof ireq);
4779 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4780 sizeof ireq.ifr_ifrn.ifrn_name);
4781 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4782 args[0] = 1; /* request Prism header */
4783 args[1] = channel; /* set channel */
4784 memcpy(ireq.u.name, args, 2*sizeof (int));
4785 ioctl(sock_fd, cmd, &ireq);
4788 case MONITOR_RT2500:
4790 * Disallow transmission - that turns on the
4793 memset(&ireq, 0, sizeof ireq);
4794 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4795 sizeof ireq.ifr_ifrn.ifrn_name);
4796 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4797 args[0] = 0; /* disallow transmitting */
4798 memcpy(ireq.u.name, args, sizeof (int));
4799 ioctl(sock_fd, cmd, &ireq);
4802 case MONITOR_RT2570:
4804 * Force the Prism header.
4806 memset(&ireq, 0, sizeof ireq);
4807 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4808 sizeof ireq.ifr_ifrn.ifrn_name);
4809 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4810 args[0] = 1; /* request Prism header */
4811 memcpy(ireq.u.name, args, sizeof (int));
4812 ioctl(sock_fd, cmd, &ireq);
4817 * Force the Prism header.
4819 memset(&ireq, 0, sizeof ireq);
4820 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4821 sizeof ireq.ifr_ifrn.ifrn_name);
4822 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4823 ireq.u.data.length = 1; /* 1 argument */
4824 ireq.u.data.pointer = "1";
4825 ireq.u.data.flags = 0;
4826 ioctl(sock_fd, cmd, &ireq);
4829 case MONITOR_RTL8XXX:
4831 * Force the Prism header.
4833 memset(&ireq, 0, sizeof ireq);
4834 strncpy(ireq.ifr_ifrn.ifrn_name, device,
4835 sizeof ireq.ifr_ifrn.ifrn_name);
4836 ireq.ifr_ifrn.ifrn_name[sizeof ireq.ifr_ifrn.ifrn_name - 1] = 0;
4837 args[0] = 1; /* request Prism header */
4838 memcpy(ireq.u.name, args, sizeof (int));
4839 ioctl(sock_fd, cmd, &ireq);
4844 * Now bring the interface back up if we brought it down.
4846 if (oldflags != 0) {
4847 ifr.ifr_flags = oldflags;
4848 if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
4849 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4850 "%s: Can't set flags: %s", device, strerror(errno));
4853 * At least try to restore the old mode on the
4856 if (ioctl(handle->fd, SIOCSIWMODE, &ireq) == -1) {
4858 * Scientist, you've failed.
4861 "Can't restore interface wireless mode (SIOCSIWMODE failed: %s).\n"
4862 "Please adjust manually.\n",
4870 * Note that we have to put the old mode back when we
4873 handle->md.must_do_on_close |= MUST_CLEAR_RFMON;
4876 * Add this to the list of pcaps to close when we exit.
4878 pcap_add_to_pcaps_to_close(handle);
4882 #endif /* IW_MODE_MONITOR */
4885 * Try various mechanisms to enter monitor mode.
4888 enter_rfmon_mode(pcap_t *handle, int sock_fd, const char *device)
4890 #if defined(HAVE_LIBNL) || defined(IW_MODE_MONITOR)
4895 ret = enter_rfmon_mode_mac80211(handle, sock_fd, device);
4897 return ret; /* error attempting to do so */
4899 return 1; /* success */
4900 #endif /* HAVE_LIBNL */
4902 #ifdef IW_MODE_MONITOR
4903 ret = enter_rfmon_mode_wext(handle, sock_fd, device);
4905 return ret; /* error attempting to do so */
4907 return 1; /* success */
4908 #endif /* IW_MODE_MONITOR */
4911 * Either none of the mechanisms we know about work or none
4912 * of those mechanisms are available, so we can't do monitor
4919 * Find out if we have any form of fragmentation/reassembly offloading.
4921 * We do so using SIOCETHTOOL checking for various types of offloading;
4922 * if SIOCETHTOOL isn't defined, or we don't have any #defines for any
4923 * of the types of offloading, there's nothing we can do to check, so
4924 * we just say "no, we don't".
4926 #if defined(SIOCETHTOOL) && (defined(ETHTOOL_GTSO) || defined(ETHTOOL_GUFO) || defined(ETHTOOL_GGSO) || defined(ETHTOOL_GFLAGS) || defined(ETHTOOL_GGRO))
4928 iface_ethtool_ioctl(pcap_t *handle, int cmd, const char *cmdname)
4931 struct ethtool_value eval;
4933 memset(&ifr, 0, sizeof(ifr));
4934 strncpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name));
4936 ifr.ifr_data = (caddr_t)&eval;
4937 if (ioctl(handle->fd, SIOCETHTOOL, &ifr) == -1) {
4938 if (errno == EOPNOTSUPP) {
4940 * OK, let's just return 0, which, in our
4941 * case, either means "no, what we're asking
4942 * about is not enabled" or "all the flags
4943 * are clear (i.e., nothing is enabled)".
4947 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
4948 "%s: SIOETHTOOL(%s) ioctl failed: %s", handle->opt.source,
4949 cmdname, strerror(errno));
4956 iface_get_offload(pcap_t *handle)
4961 ret = iface_ethtool_ioctl(handle, ETHTOOL_GTSO, "ETHTOOL_GTSO");
4965 return 1; /* TCP segmentation offloading on */
4969 ret = iface_ethtool_ioctl(handle, ETHTOOL_GUFO, "ETHTOOL_GUFO");
4973 return 1; /* UDP fragmentation offloading on */
4978 * XXX - will this cause large unsegmented packets to be
4979 * handed to PF_PACKET sockets on transmission? If not,
4980 * this need not be checked.
4982 ret = iface_ethtool_ioctl(handle, ETHTOOL_GGSO, "ETHTOOL_GGSO");
4986 return 1; /* generic segmentation offloading on */
4989 #ifdef ETHTOOL_GFLAGS
4990 ret = iface_ethtool_ioctl(handle, ETHTOOL_GFLAGS, "ETHTOOL_GFLAGS");
4993 if (ret & ETH_FLAG_LRO)
4994 return 1; /* large receive offloading on */
4999 * XXX - will this cause large reassembled packets to be
5000 * handed to PF_PACKET sockets on receipt? If not,
5001 * this need not be checked.
5003 ret = iface_ethtool_ioctl(handle, ETHTOOL_GGRO, "ETHTOOL_GGRO");
5007 return 1; /* generic (large) receive offloading on */
5012 #else /* SIOCETHTOOL */
5014 iface_get_offload(pcap_t *handle _U_)
5017 * XXX - do we need to get this information if we don't
5018 * have the ethtool ioctls? If so, how do we do that?
5022 #endif /* SIOCETHTOOL */
5024 #endif /* HAVE_PF_PACKET_SOCKETS */
5026 /* ===== Functions to interface to the older kernels ================== */
5029 * Try to open a packet socket using the old kernel interface.
5030 * Returns 1 on success and a PCAP_ERROR_ value on an error.
5033 activate_old(pcap_t *handle)
5037 const char *device = handle->opt.source;
5038 struct utsname utsname;
5041 /* Open the socket */
5043 handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
5044 if (handle->fd == -1) {
5045 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
5046 "socket: %s", pcap_strerror(errno));
5047 if (errno == EPERM || errno == EACCES) {
5049 * You don't have permission to open the
5052 return PCAP_ERROR_PERM_DENIED;
5061 /* It worked - we are using the old interface */
5062 handle->md.sock_packet = 1;
5064 /* ...which means we get the link-layer header. */
5065 handle->md.cooked = 0;
5067 /* Bind to the given device */
5069 if (strcmp(device, "any") == 0) {
5070 strncpy(handle->errbuf, "pcap_activate: The \"any\" device isn't supported on 2.0[.x]-kernel systems",
5074 if (iface_bind_old(handle->fd, device, handle->errbuf) == -1)
5078 * Try to get the link-layer type.
5080 arptype = iface_get_arptype(handle->fd, device, handle->errbuf);
5085 * Try to find the DLT_ type corresponding to that
5088 map_arphrd_to_dlt(handle, arptype, 0);
5089 if (handle->linktype == -1) {
5090 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
5091 "unknown arptype %d", arptype);
5095 /* Go to promisc mode if requested */
5097 if (handle->opt.promisc) {
5098 memset(&ifr, 0, sizeof(ifr));
5099 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
5100 if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
5101 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
5102 "SIOCGIFFLAGS: %s", pcap_strerror(errno));
5105 if ((ifr.ifr_flags & IFF_PROMISC) == 0) {
5107 * Promiscuous mode isn't currently on,
5108 * so turn it on, and remember that
5109 * we should turn it off when the
5114 * If we haven't already done so, arrange
5115 * to have "pcap_close_all()" called when
5118 if (!pcap_do_addexit(handle)) {
5120 * "atexit()" failed; don't put
5121 * the interface in promiscuous
5122 * mode, just give up.
5127 ifr.ifr_flags |= IFF_PROMISC;
5128 if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
5129 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
5131 pcap_strerror(errno));
5134 handle->md.must_do_on_close |= MUST_CLEAR_PROMISC;
5137 * Add this to the list of pcaps
5138 * to close when we exit.
5140 pcap_add_to_pcaps_to_close(handle);
5145 * Compute the buffer size.
5147 * We're using SOCK_PACKET, so this might be a 2.0[.x]
5148 * kernel, and might require special handling - check.
5150 if (uname(&utsname) < 0 ||
5151 strncmp(utsname.release, "2.0", 3) == 0) {
5153 * Either we couldn't find out what kernel release
5154 * this is, or it's a 2.0[.x] kernel.
5156 * In the 2.0[.x] kernel, a "recvfrom()" on
5157 * a SOCK_PACKET socket, with MSG_TRUNC set, will
5158 * return the number of bytes read, so if we pass
5159 * a length based on the snapshot length, it'll
5160 * return the number of bytes from the packet
5161 * copied to userland, not the actual length
5164 * This means that, for example, the IP dissector
5165 * in tcpdump will get handed a packet length less
5166 * than the length in the IP header, and will
5167 * complain about "truncated-ip".
5169 * So we don't bother trying to copy from the
5170 * kernel only the bytes in which we're interested,
5171 * but instead copy them all, just as the older
5172 * versions of libpcap for Linux did.
5174 * The buffer therefore needs to be big enough to
5175 * hold the largest packet we can get from this
5176 * device. Unfortunately, we can't get the MRU
5177 * of the network; we can only get the MTU. The
5178 * MTU may be too small, in which case a packet larger
5179 * than the buffer size will be truncated *and* we
5180 * won't get the actual packet size.
5182 * However, if the snapshot length is larger than
5183 * the buffer size based on the MTU, we use the
5184 * snapshot length as the buffer size, instead;
5185 * this means that with a sufficiently large snapshot
5186 * length we won't artificially truncate packets
5187 * to the MTU-based size.
5189 * This mess just one of many problems with packet
5190 * capture on 2.0[.x] kernels; you really want a
5191 * 2.2[.x] or later kernel if you want packet capture
5194 mtu = iface_get_mtu(handle->fd, device, handle->errbuf);
5197 handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
5198 if (handle->bufsize < handle->snapshot)
5199 handle->bufsize = handle->snapshot;
5202 * This is a 2.2[.x] or later kernel.
5204 * We can safely pass "recvfrom()" a byte count
5205 * based on the snapshot length.
5207 handle->bufsize = handle->snapshot;
5211 * Default value for offset to align link-layer payload
5212 * on a 4-byte boundary.
5220 * Bind the socket associated with FD to the given device using the
5221 * interface of the old kernels.
5224 iface_bind_old(int fd, const char *device, char *ebuf)
5226 struct sockaddr saddr;
5228 socklen_t errlen = sizeof(err);
5230 memset(&saddr, 0, sizeof(saddr));
5231 strncpy(saddr.sa_data, device, sizeof(saddr.sa_data));
5232 if (bind(fd, &saddr, sizeof(saddr)) == -1) {
5233 snprintf(ebuf, PCAP_ERRBUF_SIZE,
5234 "bind: %s", pcap_strerror(errno));
5238 /* Any pending errors, e.g., network is down? */
5240 if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
5241 snprintf(ebuf, PCAP_ERRBUF_SIZE,
5242 "getsockopt: %s", pcap_strerror(errno));
5247 snprintf(ebuf, PCAP_ERRBUF_SIZE,
5248 "bind: %s", pcap_strerror(err));
5256 /* ===== System calls available on all supported kernels ============== */
5259 * Query the kernel for the MTU of the given interface.
5262 iface_get_mtu(int fd, const char *device, char *ebuf)
5267 return BIGGER_THAN_ALL_MTUS;
5269 memset(&ifr, 0, sizeof(ifr));
5270 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
5272 if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) {
5273 snprintf(ebuf, PCAP_ERRBUF_SIZE,
5274 "SIOCGIFMTU: %s", pcap_strerror(errno));
5282 * Get the hardware type of the given interface as ARPHRD_xxx constant.
5285 iface_get_arptype(int fd, const char *device, char *ebuf)
5289 memset(&ifr, 0, sizeof(ifr));
5290 strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
5292 if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) {
5293 snprintf(ebuf, PCAP_ERRBUF_SIZE,
5294 "SIOCGIFHWADDR: %s", pcap_strerror(errno));
5295 if (errno == ENODEV) {
5299 return PCAP_ERROR_NO_SUCH_DEVICE;
5304 return ifr.ifr_hwaddr.sa_family;
5307 #ifdef SO_ATTACH_FILTER
5309 fix_program(pcap_t *handle, struct sock_fprog *fcode, int is_mmapped)
5313 register struct bpf_insn *p;
5318 * Make a copy of the filter, and modify that copy if
5321 prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len;
5322 len = handle->fcode.bf_len;
5323 f = (struct bpf_insn *)malloc(prog_size);
5325 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
5326 "malloc: %s", pcap_strerror(errno));
5329 memcpy(f, handle->fcode.bf_insns, prog_size);
5331 fcode->filter = (struct sock_filter *) f;
5333 for (i = 0; i < len; ++i) {
5336 * What type of instruction is this?
5338 switch (BPF_CLASS(p->code)) {
5342 * It's a return instruction; are we capturing
5343 * in memory-mapped mode?
5347 * No; is the snapshot length a constant,
5348 * rather than the contents of the
5351 if (BPF_MODE(p->code) == BPF_K) {
5353 * Yes - if the value to be returned,
5354 * i.e. the snapshot length, is
5355 * anything other than 0, make it
5356 * 65535, so that the packet is
5357 * truncated by "recvfrom()",
5358 * not by the filter.
5360 * XXX - there's nothing we can
5361 * easily do if it's getting the
5362 * value from the accumulator; we'd
5363 * have to insert code to force
5364 * non-zero values to be 65535.
5375 * It's a load instruction; is it loading
5378 switch (BPF_MODE(p->code)) {
5384 * Yes; are we in cooked mode?
5386 if (handle->md.cooked) {
5388 * Yes, so we need to fix this
5391 if (fix_offset(p) < 0) {
5393 * We failed to do so.
5394 * Return 0, so our caller
5395 * knows to punt to userland.
5405 return 1; /* we succeeded */
5409 fix_offset(struct bpf_insn *p)
5412 * What's the offset?
5414 if (p->k >= SLL_HDR_LEN) {
5416 * It's within the link-layer payload; that starts at an
5417 * offset of 0, as far as the kernel packet filter is
5418 * concerned, so subtract the length of the link-layer
5421 p->k -= SLL_HDR_LEN;
5422 } else if (p->k == 0) {
5424 * It's the packet type field; map it to the special magic
5425 * kernel offset for that field.
5427 p->k = SKF_AD_OFF + SKF_AD_PKTTYPE;
5428 } else if (p->k == 14) {
5430 * It's the protocol field; map it to the special magic
5431 * kernel offset for that field.
5433 p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
5434 } else if ((bpf_int32)(p->k) > 0) {
5436 * It's within the header, but it's not one of those
5437 * fields; we can't do that in the kernel, so punt
5446 set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode)
5448 int total_filter_on = 0;
5454 * The socket filter code doesn't discard all packets queued
5455 * up on the socket when the filter is changed; this means
5456 * that packets that don't match the new filter may show up
5457 * after the new filter is put onto the socket, if those
5458 * packets haven't yet been read.
5460 * This means, for example, that if you do a tcpdump capture
5461 * with a filter, the first few packets in the capture might
5462 * be packets that wouldn't have passed the filter.
5464 * We therefore discard all packets queued up on the socket
5465 * when setting a kernel filter. (This isn't an issue for
5466 * userland filters, as the userland filtering is done after
5467 * packets are queued up.)
5469 * To flush those packets, we put the socket in read-only mode,
5470 * and read packets from the socket until there are no more to
5473 * In order to keep that from being an infinite loop - i.e.,
5474 * to keep more packets from arriving while we're draining
5475 * the queue - we put the "total filter", which is a filter
5476 * that rejects all packets, onto the socket before draining
5479 * This code deliberately ignores any errors, so that you may
5480 * get bogus packets if an error occurs, rather than having
5481 * the filtering done in userland even if it could have been
5482 * done in the kernel.
5484 if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
5485 &total_fcode, sizeof(total_fcode)) == 0) {
5489 * Note that we've put the total filter onto the socket.
5491 total_filter_on = 1;
5494 * Save the socket's current mode, and put it in
5495 * non-blocking mode; we drain it by reading packets
5496 * until we get an error (which is normally a
5497 * "nothing more to be read" error).
5499 save_mode = fcntl(handle->fd, F_GETFL, 0);
5500 if (save_mode != -1 &&
5501 fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) {
5502 while (recv(handle->fd, &drain, sizeof drain,
5506 fcntl(handle->fd, F_SETFL, save_mode);
5507 if (save_errno != EAGAIN) {
5509 reset_kernel_filter(handle);
5510 snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
5511 "recv: %s", pcap_strerror(save_errno));
5518 * Now attach the new filter.
5520 ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
5521 fcode, sizeof(*fcode));
5522 if (ret == -1 && total_filter_on) {
5524 * Well, we couldn't set that filter on the socket,
5525 * but we could set the total filter on the socket.
5527 * This could, for example, mean that the filter was
5528 * too big to put into the kernel, so we'll have to
5529 * filter in userland; in any case, we'll be doing
5530 * filtering in userland, so we need to remove the
5531 * total filter so we see packets.
5536 * XXX - if this fails, we're really screwed;
5537 * we have the total filter on the socket,
5538 * and it won't come off. What do we do then?
5540 reset_kernel_filter(handle);
5548 reset_kernel_filter(pcap_t *handle)
5551 * setsockopt() barfs unless it get a dummy parameter.
5552 * valgrind whines unless the value is initialized,
5553 * as it has no idea that setsockopt() ignores its
5558 return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
5559 &dummy, sizeof(dummy));