2 * The actual capturing loop, getting packets and storing it
6 * Ethereal - Network traffic analyzer
7 * By Gerald Combs <gerald@ethereal.com>
8 * Copyright 1998 Gerald Combs
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version 2
13 * of the License, or (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
28 * Capture loop (internal interface).
30 * It will open the input and output files, capture the packets,
31 * change ringbuffer output files while capturing and close all files again.
33 * The input file can be a network interface or capture pipe (unix only).
34 * The output file can be a single or a ringbuffer file handled by wiretap.
54 #ifdef HAVE_SYS_TYPES_H
55 # include <sys/types.h>
58 #ifdef HAVE_SYS_STAT_H
59 # include <sys/stat.h>
69 #include <epan/packet.h>
71 #include "capture_sync.h"
72 #include "pcap-util.h"
74 #include "simple_dialog.h"
76 #include "conditions.h"
77 #include "capture_stop_conditions.h"
78 #include "ringbuffer.h"
80 #include "wiretap/libpcap.h"
81 #include "wiretap/wtap.h"
82 #include "wiretap/wtap-capture.h"
84 #include <epan/prefs.h>
85 /* XXX - try to remove this later */
87 /* XXX - try to remove this later */
90 #include <epan/dissectors/packet-ap1394.h>
91 #include <epan/dissectors/packet-atalk.h>
92 #include <epan/dissectors/packet-atm.h>
93 #include <epan/dissectors/packet-clip.h>
94 #include <epan/dissectors/packet-eth.h>
95 #include <epan/dissectors/packet-fddi.h>
96 #include <epan/dissectors/packet-null.h>
97 #include <epan/dissectors/packet-ppp.h>
98 #include <epan/dissectors/packet-raw.h>
99 #include <epan/dissectors/packet-sll.h>
100 #include <epan/dissectors/packet-tr.h>
101 #include <epan/dissectors/packet-ieee80211.h>
102 #include <epan/dissectors/packet-chdlc.h>
103 #include <epan/dissectors/packet-prism.h>
104 #include <epan/dissectors/packet-ipfc.h>
105 #include <epan/dissectors/packet-arcnet.h>
111 * We don't want to do a "select()" on the pcap_t's file descriptor on
112 * BSD (because "select()" doesn't work correctly on BPF devices on at
113 * least some releases of some flavors of BSD), and we don't want to do
114 * it on Windows (because "select()" is something for sockets, not for
115 * arbitrary handles). (Note that "Windows" here includes Cygwin;
116 * even in its pretend-it's-UNIX environment, we're using WinPcap, not
119 * We *do* want to do it on other platforms, as, on other platforms (with
120 * the possible exception of Ultrix and Digital UNIX), the read timeout
121 * doesn't expire if no packets have arrived, so a "pcap_dispatch()" call
122 * will block until packets arrive, causing the UI to hang.
124 * XXX - the various BSDs appear to define BSD in <sys/param.h>; we don't
125 * want to include it if it's not present on this platform, however.
127 #if !defined(__FreeBSD__) && !defined(__NetBSD__) && !defined(__OpenBSD__) && \
128 !defined(__bsdi__) && !defined(__APPLE__) && !defined(_WIN32) && \
130 # define MUST_DO_SELECT
134 typedef struct _loop_data {
136 gboolean go; /* TRUE as long as we're supposed to keep capturing */
137 int err; /* if non-zero, error seen while capturing */
138 gint packets_max; /* Number of packets we're supposed to capture - 0 means infinite */
139 gint packets_sync_pipe; /* packets not already send out to the sync_pipe */
140 packet_counts counts; /* several packet type counters */
142 /* pcap "input file" */
143 pcap_t *pcap_h; /* pcap handle */
144 gboolean pcap_err; /* TRUE if error from pcap */
145 #ifdef MUST_DO_SELECT
146 int pcap_fd; /* pcap file descriptor */
149 /* capture pipe (unix only "input file") */
150 gboolean from_cap_pipe; /* TRUE if we are capturing data from a capture pipe */
152 struct pcap_hdr cap_pipe_hdr;
153 int cap_pipe_fd; /* the file descriptor of the capture pipe */
154 gboolean cap_pipe_modified; /* TRUE if data in the pipe uses modified pcap headers */
155 gboolean cap_pipe_byte_swapped; /* TRUE if data in the pipe is byte swapped */
156 unsigned int cap_pipe_bytes_to_read;/* Used by cap_pipe_dispatch */
157 unsigned int cap_pipe_bytes_read; /* Used by cap_pipe_dispatch */
159 STATE_EXPECT_REC_HDR,
165 enum { PIPOK, PIPEOF, PIPERR, PIPNEXIST } cap_pipe_err;
168 /* wiretap (output file) */
169 wtap_dumper *wtap_pdh;
176 * Timeout, in milliseconds, for reads from the stream of captured packets.
178 #define CAP_READ_TIMEOUT 250
180 static void capture_loop_packet_cb(guchar *user, const struct pcap_pkthdr *phdr,
182 static void capture_loop_popup_errmsg(capture_options *capture_opts, const char *errmsg);
183 static void capture_loop_get_errmsg(char *errmsg, int errmsglen, const char *fname,
184 int err, gboolean is_close);
189 /* Take care of byte order in the libpcap headers read from pipes.
190 * (function taken from wiretap/libpcap.c) */
192 cap_pipe_adjust_header(loop_data *ld, struct pcap_hdr *hdr, struct pcaprec_hdr *rechdr)
194 if (ld->cap_pipe_byte_swapped) {
195 /* Byte-swap the record header fields. */
196 rechdr->ts_sec = BSWAP32(rechdr->ts_sec);
197 rechdr->ts_usec = BSWAP32(rechdr->ts_usec);
198 rechdr->incl_len = BSWAP32(rechdr->incl_len);
199 rechdr->orig_len = BSWAP32(rechdr->orig_len);
202 /* In file format version 2.3, the "incl_len" and "orig_len" fields were
203 swapped, in order to match the BPF header layout.
205 Unfortunately, some files were, according to a comment in the "libpcap"
206 source, written with version 2.3 in their headers but without the
207 interchanged fields, so if "incl_len" is greater than "orig_len" - which
208 would make no sense - we assume that we need to swap them. */
209 if (hdr->version_major == 2 &&
210 (hdr->version_minor < 3 ||
211 (hdr->version_minor == 3 && rechdr->incl_len > rechdr->orig_len))) {
214 temp = rechdr->orig_len;
215 rechdr->orig_len = rechdr->incl_len;
216 rechdr->incl_len = temp;
220 /* Mimic pcap_open_live() for pipe captures
221 * We check if "pipename" is "-" (stdin) or a FIFO, open it, and read the
223 * N.B. : we can't read the libpcap formats used in RedHat 6.1 or SuSE 6.3
224 * because we can't seek on pipes (see wiretap/libpcap.c for details) */
226 cap_pipe_open_live(char *pipename, struct pcap_hdr *hdr, loop_data *ld,
227 char *errmsg, int errmsgl)
229 struct stat pipe_stat;
233 unsigned int bytes_read;
235 struct timeval timeout;
238 * XXX Ethereal blocks until we return
240 if (strcmp(pipename, "-") == 0)
241 fd = 0; /* read from stdin */
243 if (stat(pipename, &pipe_stat) < 0) {
244 if (errno == ENOENT || errno == ENOTDIR)
245 ld->cap_pipe_err = PIPNEXIST;
247 g_snprintf(errmsg, errmsgl,
248 "The capture session could not be initiated "
249 "due to error on pipe: %s", strerror(errno));
250 ld->cap_pipe_err = PIPERR;
254 if (! S_ISFIFO(pipe_stat.st_mode)) {
255 if (S_ISCHR(pipe_stat.st_mode)) {
257 * Assume the user specified an interface on a system where
258 * interfaces are in /dev. Pretend we haven't seen it.
260 ld->cap_pipe_err = PIPNEXIST;
262 g_snprintf(errmsg, errmsgl,
263 "The capture session could not be initiated because\n"
264 "\"%s\" is neither an interface nor a pipe", pipename);
265 ld->cap_pipe_err = PIPERR;
269 fd = open(pipename, O_RDONLY | O_NONBLOCK);
271 g_snprintf(errmsg, errmsgl,
272 "The capture session could not be initiated "
273 "due to error on pipe open: %s", strerror(errno));
274 ld->cap_pipe_err = PIPERR;
279 ld->from_cap_pipe = TRUE;
281 /* read the pcap header */
284 while (bytes_read < sizeof magic) {
287 timeout.tv_usec = CAP_READ_TIMEOUT*1000;
288 sel_ret = select(fd+1, &rfds, NULL, NULL, &timeout);
290 g_snprintf(errmsg, errmsgl,
291 "Unexpected error from select: %s", strerror(errno));
293 } else if (sel_ret > 0) {
294 b = read(fd, ((char *)&magic)+bytes_read, sizeof magic-bytes_read);
297 g_snprintf(errmsg, errmsgl, "End of file on pipe during open");
299 g_snprintf(errmsg, errmsgl, "Error on pipe during open: %s",
309 /* Host that wrote it has our byte order, and was running
310 a program using either standard or ss990417 libpcap. */
311 ld->cap_pipe_byte_swapped = FALSE;
312 ld->cap_pipe_modified = FALSE;
314 case PCAP_MODIFIED_MAGIC:
315 /* Host that wrote it has our byte order, but was running
316 a program using either ss990915 or ss991029 libpcap. */
317 ld->cap_pipe_byte_swapped = FALSE;
318 ld->cap_pipe_modified = TRUE;
320 case PCAP_SWAPPED_MAGIC:
321 /* Host that wrote it has a byte order opposite to ours,
322 and was running a program using either standard or
324 ld->cap_pipe_byte_swapped = TRUE;
325 ld->cap_pipe_modified = FALSE;
327 case PCAP_SWAPPED_MODIFIED_MAGIC:
328 /* Host that wrote it out has a byte order opposite to
329 ours, and was running a program using either ss990915
330 or ss991029 libpcap. */
331 ld->cap_pipe_byte_swapped = TRUE;
332 ld->cap_pipe_modified = TRUE;
335 /* Not a "libpcap" type we know about. */
336 g_snprintf(errmsg, errmsgl, "Unrecognized libpcap format");
340 /* Read the rest of the header */
342 while (bytes_read < sizeof(struct pcap_hdr)) {
345 timeout.tv_usec = CAP_READ_TIMEOUT*1000;
346 sel_ret = select(fd+1, &rfds, NULL, NULL, &timeout);
348 g_snprintf(errmsg, errmsgl,
349 "Unexpected error from select: %s", strerror(errno));
351 } else if (sel_ret > 0) {
352 b = read(fd, ((char *)hdr)+bytes_read,
353 sizeof(struct pcap_hdr) - bytes_read);
356 g_snprintf(errmsg, errmsgl, "End of file on pipe during open");
358 g_snprintf(errmsg, errmsgl, "Error on pipe during open: %s",
366 if (ld->cap_pipe_byte_swapped) {
367 /* Byte-swap the header fields about which we care. */
368 hdr->version_major = BSWAP16(hdr->version_major);
369 hdr->version_minor = BSWAP16(hdr->version_minor);
370 hdr->snaplen = BSWAP32(hdr->snaplen);
371 hdr->network = BSWAP32(hdr->network);
374 if (hdr->version_major < 2) {
375 g_snprintf(errmsg, errmsgl, "Unable to read old libpcap format");
379 ld->cap_pipe_state = STATE_EXPECT_REC_HDR;
380 ld->cap_pipe_err = PIPOK;
384 ld->cap_pipe_err = PIPERR;
391 /* We read one record from the pipe, take care of byte order in the record
392 * header, write the record to the capture file, and update capture statistics. */
394 cap_pipe_dispatch(int fd, loop_data *ld, struct pcap_hdr *hdr,
395 struct pcaprec_modified_hdr *rechdr, guchar *data,
396 char *errmsg, int errmsgl)
398 struct pcap_pkthdr phdr;
400 enum { PD_REC_HDR_READ, PD_DATA_READ, PD_PIPE_EOF, PD_PIPE_ERR,
403 switch (ld->cap_pipe_state) {
405 case STATE_EXPECT_REC_HDR:
406 ld->cap_pipe_bytes_to_read = ld->cap_pipe_modified ?
407 sizeof(struct pcaprec_modified_hdr) : sizeof(struct pcaprec_hdr);
408 ld->cap_pipe_bytes_read = 0;
409 ld->cap_pipe_state = STATE_READ_REC_HDR;
412 case STATE_READ_REC_HDR:
413 b = read(fd, ((char *)rechdr)+ld->cap_pipe_bytes_read,
414 ld->cap_pipe_bytes_to_read - ld->cap_pipe_bytes_read);
417 result = PD_PIPE_EOF;
419 result = PD_PIPE_ERR;
422 if ((ld->cap_pipe_bytes_read += b) < ld->cap_pipe_bytes_to_read)
424 result = PD_REC_HDR_READ;
427 case STATE_EXPECT_DATA:
428 ld->cap_pipe_bytes_read = 0;
429 ld->cap_pipe_state = STATE_READ_DATA;
432 case STATE_READ_DATA:
433 b = read(fd, data+ld->cap_pipe_bytes_read, rechdr->hdr.incl_len - ld->cap_pipe_bytes_read);
436 result = PD_PIPE_EOF;
438 result = PD_PIPE_ERR;
441 if ((ld->cap_pipe_bytes_read += b) < rechdr->hdr.incl_len)
443 result = PD_DATA_READ;
447 g_snprintf(errmsg, errmsgl, "cap_pipe_dispatch: invalid state");
450 } /* switch (ld->cap_pipe_state) */
453 * We've now read as much data as we were expecting, so process it.
457 case PD_REC_HDR_READ:
458 /* We've read the header. Take care of byte order. */
459 cap_pipe_adjust_header(ld, hdr, &rechdr->hdr);
460 if (rechdr->hdr.incl_len > WTAP_MAX_PACKET_SIZE) {
461 g_snprintf(errmsg, errmsgl, "Frame %u too long (%d bytes)",
462 ld->counts.total+1, rechdr->hdr.incl_len);
465 ld->cap_pipe_state = STATE_EXPECT_DATA;
469 /* Fill in a "struct pcap_pkthdr", and process the packet. */
470 phdr.ts.tv_sec = rechdr->hdr.ts_sec;
471 phdr.ts.tv_usec = rechdr->hdr.ts_usec;
472 phdr.caplen = rechdr->hdr.incl_len;
473 phdr.len = rechdr->hdr.orig_len;
475 capture_loop_packet_cb((guchar *)ld, &phdr, data);
477 ld->cap_pipe_state = STATE_EXPECT_REC_HDR;
481 ld->cap_pipe_err = PIPEOF;
485 g_snprintf(errmsg, errmsgl, "Error reading from pipe: %s",
492 ld->cap_pipe_err = PIPERR;
493 /* Return here rather than inside the switch to prevent GCC warning */
496 #endif /* not _WIN32 */
499 /* open the capture input file (pcap or capture pipe) */
500 static int capture_loop_open_input(capture_options *capture_opts, loop_data *ld, char *errmsg, int errmsg_len) {
501 gchar open_err_str[PCAP_ERRBUF_SIZE];
502 const char *set_linktype_err_str;
505 WORD wVersionRequested;
508 static const char ppamsg[] = "can't find PPA for ";
512 /* Initialize Windows Socket if we are in a WIN32 OS
513 This needs to be done before querying the interface for network/netmask */
515 /* XXX - do we really require 1.1 or earlier?
516 Are there any versions that support only 2.0 or higher? */
517 wVersionRequested = MAKEWORD(1, 1);
518 err = WSAStartup(wVersionRequested, &wsaData);
523 g_snprintf(errmsg, errmsg_len,
524 "Couldn't initialize Windows Sockets: Network system not ready for network communication");
527 case WSAVERNOTSUPPORTED:
528 g_snprintf(errmsg, errmsg_len,
529 "Couldn't initialize Windows Sockets: Windows Sockets version %u.%u not supported",
530 LOBYTE(wVersionRequested), HIBYTE(wVersionRequested));
534 g_snprintf(errmsg, errmsg_len,
535 "Couldn't initialize Windows Sockets: Blocking operation is in progress");
539 g_snprintf(errmsg, errmsg_len,
540 "Couldn't initialize Windows Sockets: Limit on the number of tasks supported by this WinSock implementation has been reached");
544 g_snprintf(errmsg, errmsg_len,
545 "Couldn't initialize Windows Sockets: Bad pointer passed to WSAStartup");
549 g_snprintf(errmsg, errmsg_len,
550 "Couldn't initialize Windows Sockets: error %d", err);
557 /* Open the network interface to capture from it.
558 Some versions of libpcap may put warnings into the error buffer
559 if they succeed; to tell if that's happened, we have to clear
560 the error buffer, and check if it's still a null string. */
561 open_err_str[0] = '\0';
562 ld->pcap_h = pcap_open_live(cfile.iface,
563 capture_opts->has_snaplen ? capture_opts->snaplen :
564 WTAP_MAX_PACKET_SIZE,
565 capture_opts->promisc_mode, CAP_READ_TIMEOUT,
568 if (ld->pcap_h != NULL) {
569 /* we've opened "cfile.iface" as a network device */
571 /* try to set the capture buffer size */
572 if (pcap_setbuff(ld->pcap_h, capture_opts->buffer_size * 1024 * 1024) != 0) {
573 simple_dialog(ESD_TYPE_INFO, ESD_BTN_OK,
574 "%sCouldn't set the capture buffer size!%s\n"
576 "The capture buffer size of %luMB seems to be too high for your machine,\n"
577 "the default of 1MB will be used.\n"
579 "Nonetheless, the capture is started.\n",
580 simple_dialog_primary_start(), simple_dialog_primary_end(), capture_opts->buffer_size);
584 /* setting the data link type only works on real interfaces */
585 if (capture_opts->linktype != -1) {
586 set_linktype_err_str = set_pcap_linktype(ld->pcap_h, cfile.iface,
587 capture_opts->linktype);
588 if (set_linktype_err_str != NULL) {
589 g_snprintf(errmsg, errmsg_len, "Unable to set data link type (%s).",
590 set_linktype_err_str);
595 /* We couldn't open "cfile.iface" as a network device. */
597 /* On Windows, we don't support capturing on pipes, so we give up.
598 If this is a child process that does the capturing in sync
599 mode or fork mode, it shouldn't do any UI stuff until we pop up the
600 capture-progress window, and, since we couldn't start the
601 capture, we haven't popped it up. */
602 if (!capture_opts->capture_child) {
603 main_window_update();
606 /* On Win32 OSes, the capture devices are probably available to all
607 users; don't warn about permissions problems.
609 Do, however, warn that WAN devices aren't supported. */
610 g_snprintf(errmsg, errmsg_len,
611 "The capture session could not be initiated (%s).\n"
612 "Please check that you have the proper interface specified.\n"
614 "Note that the WinPcap 2.x version of the driver Ethereal uses for packet\n"
615 "capture on Windows doesn't support capturing on PPP/WAN interfaces in\n"
616 "Windows NT/2000/XP/2003 Server, and that the WinPcap 3.0 and later versions\n"
617 "don't support capturing on PPP/WAN interfaces at all.",
621 /* try to open cfile.iface as a pipe */
622 ld->cap_pipe_fd = cap_pipe_open_live(cfile.iface, &ld->cap_pipe_hdr, ld, errmsg, errmsg_len);
624 if (ld->cap_pipe_fd == -1) {
626 /* If this is a child process that does the capturing in sync
627 * mode or fork mode, it shouldn't do any UI stuff until we pop up the
628 * capture-progress window, and, since we couldn't start the
629 * capture, we haven't popped it up.
631 if (!capture_opts->capture_child) {
632 main_window_update();
635 if (ld->cap_pipe_err == PIPNEXIST) {
636 /* Pipe doesn't exist, so output message for interface */
638 /* If we got a "can't find PPA for XXX" message, warn the user (who
639 is running Ethereal on HP-UX) that they don't have a version
640 of libpcap that properly handles HP-UX (libpcap 0.6.x and later
641 versions, which properly handle HP-UX, say "can't find /dev/dlpi
642 PPA for XXX" rather than "can't find PPA for XXX"). */
643 if (strncmp(open_err_str, ppamsg, sizeof ppamsg - 1) == 0)
646 "You are running Ethereal with a version of the libpcap library\n"
647 "that doesn't handle HP-UX network devices well; this means that\n"
648 "Ethereal may not be able to capture packets.\n"
650 "To fix this, you should install libpcap 0.6.2, or a later version\n"
651 "of libpcap, rather than libpcap 0.4 or 0.5.x. It is available in\n"
652 "packaged binary form from the Software Porting And Archive Centre\n"
653 "for HP-UX; the Centre is at http://hpux.connect.org.uk/ - the page\n"
654 "at the URL lists a number of mirror sites.";
657 g_snprintf(errmsg, errmsg_len,
658 "The capture session could not be initiated (%s).\n"
659 "Please check to make sure you have sufficient permissions, and that\n"
660 "you have the proper interface or pipe specified.%s", open_err_str,
664 * Else pipe (or file) does exist and cap_pipe_open_live() has
669 /* cap_pipe_open_live() succeeded; don't want
670 error message from pcap_open_live() */
671 open_err_str[0] = '\0';
675 #ifdef MUST_DO_SELECT
676 if (!ld->from_cap_pipe) ld->pcap_fd = pcap_fileno(ld->pcap_h);
679 /* Does "open_err_str" contain a non-empty string? If so, "pcap_open_live()"
680 returned a warning; print it, but keep capturing. */
681 if (open_err_str[0] != '\0')
682 g_warning("%s.", open_err_str);
688 /* open the capture input file (pcap or capture pipe) */
689 static void capture_loop_close_input(loop_data *ld) {
691 /* if open, close the capture pipe "input file" */
692 if (ld->cap_pipe_fd >= 0) {
693 g_assert(ld->from_cap_pipe);
694 close(ld->cap_pipe_fd);
698 /* if open, close the pcap "input file" */
699 if(ld->pcap_h != NULL) {
700 g_assert(!ld->from_cap_pipe);
701 pcap_close(ld->pcap_h);
705 /* Shut down windows sockets */
711 /* init the capture filter */
712 static int capture_loop_init_filter(loop_data *ld, char *errmsg, int errmsg_len) {
713 bpf_u_int32 netnum, netmask;
714 gchar lookup_net_err_str[PCAP_ERRBUF_SIZE];
715 struct bpf_program fcode;
717 /* capture filters only work on real interfaces */
718 if (cfile.cfilter && !ld->from_cap_pipe) {
719 /* A capture filter was specified; set it up. */
720 if (pcap_lookupnet(cfile.iface, &netnum, &netmask, lookup_net_err_str) < 0) {
722 * Well, we can't get the netmask for this interface; it's used
723 * only for filters that check for broadcast IP addresses, so
724 * we just punt and use 0. It might be nice to warn the user,
725 * but that's a pain in a GUI application, as it'd involve popping
726 * up a message box, and it's not clear how often this would make
727 * a difference (only filters that check for IP broadcast addresses
732 if (pcap_compile(ld->pcap_h, &fcode, cfile.cfilter, 1, netmask) < 0) {
733 dfilter_t *rfcode = NULL;
734 /* filter string invalid, did the user tried a display filter? */
735 if (dfilter_compile(cfile.cfilter, &rfcode) && rfcode != NULL) {
736 g_snprintf(errmsg, errmsg_len,
737 "%sInvalid capture filter: \"%s\"!%s\n"
739 "That string looks like a valid display filter; however, it isn't a valid\n"
740 "capture filter (%s).\n"
742 "Note that display filters and capture filters don't have the same syntax,\n"
743 "so you can't use most display filter expressions as capture filters.\n"
745 "See the help for a description of the capture filter syntax.",
746 simple_dialog_primary_start(), cfile.cfilter, simple_dialog_primary_end(),
747 pcap_geterr(ld->pcap_h));
748 dfilter_free(rfcode);
750 g_snprintf(errmsg, errmsg_len,
751 "%sInvalid capture filter: \"%s\"!%s\n"
753 "That string isn't a valid capture filter (%s).\n"
754 "See the help for a description of the capture filter syntax.",
755 simple_dialog_primary_start(), cfile.cfilter, simple_dialog_primary_end(),
756 pcap_geterr(ld->pcap_h));
760 if (pcap_setfilter(ld->pcap_h, &fcode) < 0) {
761 g_snprintf(errmsg, errmsg_len, "Can't install filter (%s).",
762 pcap_geterr(ld->pcap_h));
771 /* open the wiretap part of the capture output file */
772 static int capture_loop_open_wiretap_output(capture_options *capture_opts, loop_data *ld, char *errmsg, int errmsg_len) {
778 /* get packet encapsulation type and snaplen */
780 if (ld->from_cap_pipe) {
781 pcap_encap = ld->cap_pipe_hdr.network;
782 file_snaplen = ld->cap_pipe_hdr.snaplen;
786 pcap_encap = get_pcap_linktype(ld->pcap_h, cfile.iface);
787 file_snaplen = pcap_snapshot(ld->pcap_h);
790 /* Set up to write to the capture file. */
791 ld->wtap_linktype = wtap_pcap_encap_to_wtap_encap(pcap_encap);
792 if (ld->wtap_linktype == WTAP_ENCAP_UNKNOWN) {
793 g_snprintf(errmsg, errmsg_len,
794 "The network you're capturing from is of a type"
795 " that Ethereal doesn't support (data link type %d).", pcap_encap);
798 if (capture_opts->multi_files_on) {
799 ld->wtap_pdh = ringbuf_init_wtap_dump_fdopen(WTAP_FILE_PCAP, ld->wtap_linktype,
802 ld->wtap_pdh = wtap_dump_fdopen(capture_opts->save_file_fd, WTAP_FILE_PCAP,
803 ld->wtap_linktype, file_snaplen, &err);
806 if (ld->wtap_pdh == NULL) {
807 /* We couldn't set up to write to the capture file. */
810 case WTAP_ERR_CANT_OPEN:
811 strcpy(errmsg, "The file to which the capture would be saved"
812 " couldn't be created for some unknown reason.");
815 case WTAP_ERR_SHORT_WRITE:
816 strcpy(errmsg, "A full header couldn't be written to the file"
817 " to which the capture would be saved.");
822 g_snprintf(errmsg, errmsg_len,
823 "The file to which the capture would be"
824 " saved (\"%s\") could not be opened: Error %d.",
825 cfile.save_file, err);
827 g_snprintf(errmsg, errmsg_len,
828 "The file to which the capture would be"
829 " saved (\"%s\") could not be opened: %s.",
830 cfile.save_file, strerror(err));
841 static gboolean capture_loop_close_output(capture_options *capture_opts, loop_data *ld, int *err_close) {
842 if (capture_opts->multi_files_on) {
843 return ringbuf_wtap_dump_close(&cfile.save_file, err_close);
845 return wtap_dump_close(ld->wtap_pdh, err_close);
849 /* dispatch incoming packets (pcap or capture pipe) */
851 capture_loop_dispatch(capture_options *capture_opts, loop_data *ld,
852 char *errmsg, int errmsg_len) {
856 struct timeval timeout;
858 struct pcaprec_modified_hdr rechdr;
859 guchar pcap_data[WTAP_MAX_PACKET_SIZE];
863 /* dispatch from capture pipe */
864 if (ld->from_cap_pipe) {
866 FD_SET(ld->cap_pipe_fd, &set1);
868 timeout.tv_usec = CAP_READ_TIMEOUT*1000;
869 sel_ret = select(ld->cap_pipe_fd+1, &set1, NULL, NULL, &timeout);
872 if (sel_ret < 0 && errno != EINTR) {
873 g_snprintf(errmsg, errmsg_len,
874 "Unexpected error from select: %s", strerror(errno));
875 capture_loop_popup_errmsg(capture_opts, errmsg);
880 * "select()" says we can read from the pipe without blocking
882 inpkts = cap_pipe_dispatch(ld->cap_pipe_fd, ld, &ld->cap_pipe_hdr, &rechdr, pcap_data,
892 /* dispatch from pcap using select */
893 #ifdef MUST_DO_SELECT
895 * Sigh. The semantics of the read timeout argument to
896 * "pcap_open_live()" aren't particularly well specified by
897 * the "pcap" man page - at least with the BSD BPF code, the
898 * intent appears to be, at least in part, a way of cutting
899 * down the number of reads done on a capture, by blocking
900 * until the buffer fills or a timer expires - and the Linux
901 * libpcap doesn't actually support it, so we can't use it
902 * to break out of the "pcap_dispatch()" every 1/4 of a second
903 * or so. Linux's libpcap is not the only libpcap that doesn't
904 * support the read timeout.
906 * Furthermore, at least on Solaris, the bufmod STREAMS module's
907 * read timeout won't go off if no data has arrived, i.e. it cannot
908 * be used to guarantee that a read from a DLPI stream will return
909 * within a specified amount of time regardless of whether any
910 * data arrives or not.
912 * Thus, on all platforms other than BSD, we do a "select()" on the
913 * file descriptor for the capture, with a timeout of CAP_READ_TIMEOUT
914 * milliseconds, or CAP_READ_TIMEOUT*1000 microseconds.
916 * "select()", on BPF devices, doesn't work as you might expect;
917 * at least on some versions of some flavors of BSD, the timer
918 * doesn't start until a read is done, so it won't expire if
919 * only a "select()" or "poll()" is posted.
922 FD_SET(ld->pcap_fd, &set1);
924 timeout.tv_usec = CAP_READ_TIMEOUT*1000;
925 sel_ret = select(ld->pcap_fd+1, &set1, NULL, NULL, &timeout);
928 * "select()" says we can read from it without blocking; go for
931 inpkts = pcap_dispatch(ld->pcap_h, 1, capture_loop_packet_cb, (gchar *)ld);
938 if (sel_ret < 0 && errno != EINTR) {
939 g_snprintf(errmsg, errmsg_len,
940 "Unexpected error from select: %s", strerror(errno));
941 capture_loop_popup_errmsg(capture_opts, errmsg);
946 /* dispatch from pcap without select */
947 inpkts = pcap_dispatch(ld->pcap_h, 1, capture_loop_packet_cb, (gchar *) ld);
952 #endif /* MUST_DO_SELECT */
960 * This needs to be static, so that the SIGUSR1 handler can clear the "go"
965 /* Do the low-level work of a capture.
966 Returns TRUE if it succeeds, FALSE otherwise. */
968 capture_loop_start(capture_options *capture_opts, gboolean *stats_known, struct pcap_stat *stats)
970 time_t upd_time, cur_time;
972 int err_close, inpkts;
973 condition *cnd_file_duration = NULL;
974 condition *cnd_autostop_files = NULL;
975 condition *cnd_autostop_size = NULL;
976 condition *cnd_autostop_duration = NULL;
977 guint32 autostop_files = 0;
980 capture_info capture_ui;
983 gboolean show_info = capture_opts->show_info || !capture_opts->sync_mode;
986 /* init the loop data */
988 if (capture_opts->has_autostop_packets)
989 ld.packets_max = capture_opts->autostop_packets;
991 ld.packets_max = 0; /* no limit */
992 ld.err = 0; /* no error seen yet */
993 ld.wtap_linktype = WTAP_ENCAP_UNKNOWN;
995 ld.from_cap_pipe = FALSE;
996 ld.packets_sync_pipe = 0;
1005 ld.counts.netbios = 0;
1006 ld.counts.vines = 0;
1007 ld.counts.other = 0;
1011 ld.cap_pipe_fd = -1;
1013 #ifdef MUST_DO_SELECT
1017 /* We haven't yet gotten the capture statistics. */
1018 *stats_known = FALSE;
1021 /* open the "input file" from network interface or capture pipe */
1022 if (!capture_loop_open_input(capture_opts, &ld, errmsg, sizeof(errmsg))) {
1026 /* init the input filter from the network interface (capture pipe will do nothing) */
1027 if (!capture_loop_init_filter(&ld, errmsg, sizeof(errmsg))) {
1031 /* open the wiretap part of the output file (the output file is already open) */
1032 if (!capture_loop_open_wiretap_output(capture_opts, &ld, errmsg, sizeof(errmsg))) {
1036 /* XXX - capture SIGTERM and close the capture, in case we're on a
1037 Linux 2.0[.x] system and you have to explicitly close the capture
1038 stream in order to turn promiscuous mode off? We need to do that
1039 in other places as well - and I don't think that works all the
1040 time in any case, due to libpcap bugs. */
1042 if (capture_opts->capture_child) {
1043 /* Well, we should be able to start capturing.
1045 This is the child process for a sync mode capture, so sync out
1046 the capture file, so the header makes it to the file system,
1047 and send a "capture started successfully and capture file created"
1048 message to our parent so that they'll open the capture file and
1049 update its windows to indicate that we have a live capture in
1051 fflush(wtap_dump_file(ld.wtap_pdh));
1052 sync_pipe_capstart_to_parent();
1055 /* initialize capture stop (and alike) conditions */
1056 init_capture_stop_conditions();
1057 /* create stop conditions */
1058 if (capture_opts->has_autostop_filesize)
1060 cnd_new(CND_CLASS_CAPTURESIZE,(long)capture_opts->autostop_filesize);
1061 if (capture_opts->has_autostop_duration)
1062 cnd_autostop_duration =
1063 cnd_new(CND_CLASS_TIMEOUT,(gint32)capture_opts->autostop_duration);
1065 if (capture_opts->multi_files_on) {
1066 if (capture_opts->has_file_duration)
1068 cnd_new(CND_CLASS_TIMEOUT, capture_opts->file_duration);
1070 if (capture_opts->has_autostop_files)
1071 cnd_autostop_files =
1072 cnd_new(CND_CLASS_CAPTURESIZE, capture_opts->autostop_files);
1075 /* start capture info dialog */
1077 capture_ui.callback_data = &ld;
1078 capture_ui.counts = &ld.counts;
1079 capture_info_create(&capture_ui, cfile.iface);
1082 /* init the time values */
1083 start_time = time(NULL);
1084 upd_time = time(NULL);
1086 /* WOW, everything is prepared! */
1087 /* please fasten your seat belts, we will enter now the actual capture loop */
1089 main_window_update();
1091 /* dispatch incoming packets */
1092 inpkts = capture_loop_dispatch(capture_opts, &ld, errmsg, sizeof(errmsg));
1095 ld.packets_sync_pipe += inpkts;
1097 /* check capture size condition */
1098 if (cnd_autostop_size != NULL && cnd_eval(cnd_autostop_size,
1099 (guint32)wtap_get_bytes_dumped(ld.wtap_pdh))){
1100 /* Capture size limit reached, do we have another file? */
1101 if (capture_opts->multi_files_on) {
1102 if (cnd_autostop_files != NULL && cnd_eval(cnd_autostop_files, ++autostop_files)) {
1103 /* no files left: stop here */
1108 /* Switch to the next ringbuffer file */
1109 if (ringbuf_switch_file(&ld.wtap_pdh, &cfile.save_file, &capture_opts->save_file_fd, &ld.err)) {
1110 /* File switch succeeded: reset the conditions */
1111 cnd_reset(cnd_autostop_size);
1112 if (cnd_file_duration) {
1113 cnd_reset(cnd_file_duration);
1116 /* File switch failed: stop here */
1121 /* single file, stop now */
1125 } /* cnd_autostop_size */
1128 /* Only update once a second so as not to overload slow displays */
1129 cur_time = time(NULL);
1130 if (cur_time > upd_time) {
1131 upd_time = cur_time;
1133 /*if (pcap_stats(pch, stats) >= 0) {
1134 *stats_known = TRUE;
1137 /* calculate and display running time */
1139 cur_time -= start_time;
1140 capture_ui.running_time = cur_time;
1141 capture_ui.new_packets = ld.packets_sync_pipe;
1142 capture_info_update(&capture_ui);
1145 /* Let the parent process know. */
1146 if (ld.packets_sync_pipe) {
1148 fflush(wtap_dump_file(ld.wtap_pdh));
1150 if (capture_opts->capture_child) {
1151 /* This is the child process for a sync mode capture, so send
1152 our parent a message saying we've written out "ld.sync_packets"
1153 packets to the capture file. */
1154 sync_pipe_packet_count_to_parent(ld.packets_sync_pipe);
1157 ld.packets_sync_pipe = 0;
1160 /* check capture duration condition */
1161 if (cnd_autostop_duration != NULL && cnd_eval(cnd_autostop_duration)) {
1162 /* The maximum capture time has elapsed; stop the capture. */
1167 /* check capture file duration condition */
1168 if (cnd_file_duration != NULL && cnd_eval(cnd_file_duration)) {
1169 /* duration limit reached, do we have another file? */
1170 if (capture_opts->multi_files_on) {
1171 if (cnd_autostop_files != NULL && cnd_eval(cnd_autostop_files, ++autostop_files)) {
1172 /* no files left: stop here */
1177 /* Switch to the next ringbuffer file */
1178 if (ringbuf_switch_file(&ld.wtap_pdh, &cfile.save_file, &capture_opts->save_file_fd, &ld.err)) {
1179 /* file switch succeeded: reset the conditions */
1180 cnd_reset(cnd_file_duration);
1181 if(cnd_autostop_size)
1182 cnd_reset(cnd_autostop_size);
1184 /* File switch failed: stop here */
1189 /* single file, stop now */
1193 } /* cnd_file_duration */
1196 } /* while (ld.go) */
1198 /* close capture info dialog */
1200 capture_info_destroy(&capture_ui);
1203 /* delete stop conditions */
1204 if (cnd_file_duration != NULL)
1205 cnd_delete(cnd_file_duration);
1206 if (cnd_autostop_files != NULL)
1207 cnd_delete(cnd_autostop_files);
1208 if (cnd_autostop_size != NULL)
1209 cnd_delete(cnd_autostop_size);
1210 if (cnd_autostop_duration != NULL)
1211 cnd_delete(cnd_autostop_duration);
1213 /* did we had a pcap (input) error? */
1215 g_snprintf(errmsg, sizeof(errmsg), "Error while capturing packets: %s",
1216 pcap_geterr(ld.pcap_h));
1217 capture_loop_popup_errmsg(capture_opts, errmsg);
1220 else if (ld.from_cap_pipe && ld.cap_pipe_err == PIPERR)
1221 capture_loop_popup_errmsg(capture_opts, errmsg);
1224 /* did we had an error while capturing? */
1228 capture_loop_get_errmsg(errmsg, sizeof(errmsg), cfile.save_file, ld.err,
1230 capture_loop_popup_errmsg(capture_opts, errmsg);
1234 /* close the wiretap (output) file */
1235 close_ok = capture_loop_close_output(capture_opts, &ld, &err_close);
1237 /* If we've displayed a message about a write error, there's no point
1238 in displaying another message about an error on close. */
1239 if (!close_ok && write_ok) {
1240 capture_loop_get_errmsg(errmsg, sizeof(errmsg), cfile.save_file, err_close,
1242 capture_loop_popup_errmsg(capture_opts, errmsg);
1246 * XXX We exhibit different behaviour between normal mode and sync mode
1247 * when the pipe is stdin and not already at EOF. If we're a child, the
1248 * parent's stdin isn't closed, so if the user starts another capture,
1249 * cap_pipe_open_live() will very likely not see the expected magic bytes and
1250 * will say "Unrecognized libpcap format". On the other hand, in normal
1251 * mode, cap_pipe_open_live() will say "End of file on pipe during open".
1254 /* get packet drop statistics from pcap */
1255 if(ld.pcap_h != NULL) {
1256 g_assert(!ld.from_cap_pipe);
1257 /* Get the capture statistics, so we know how many packets were
1259 if (pcap_stats(ld.pcap_h, stats) >= 0) {
1260 *stats_known = TRUE;
1261 if (capture_opts->capture_child) {
1262 /* Let the parent process know. */
1263 sync_pipe_drops_to_parent(stats->ps_drop);
1266 g_snprintf(errmsg, sizeof(errmsg),
1267 "Can't get packet-drop statistics: %s",
1268 pcap_geterr(ld.pcap_h));
1269 capture_loop_popup_errmsg(capture_opts, errmsg);
1273 /* close the input file (pcap or capture pipe) */
1274 capture_loop_close_input(&ld);
1276 /* ok, if the write and the close were successful. */
1277 return write_ok && close_ok;
1280 if (capture_opts->multi_files_on) {
1281 /* cleanup ringbuffer */
1282 ringbuf_error_cleanup();
1284 /* We can't use the save file, and we have no wtap_dump stream
1285 to close in order to close it, so close the FD directly. */
1286 close(capture_opts->save_file_fd);
1288 /* We couldn't even start the capture, so get rid of the capture
1290 unlink(cfile.save_file); /* silently ignore error */
1291 g_free(cfile.save_file);
1293 cfile.save_file = NULL;
1294 capture_loop_popup_errmsg(capture_opts, errmsg);
1296 /* close the input file (pcap or cap_pipe) */
1297 capture_loop_close_input(&ld);
1303 void capture_loop_stop(void)
1310 capture_loop_get_errmsg(char *errmsg, int errmsglen, const char *fname,
1311 int err, gboolean is_close)
1316 g_snprintf(errmsg, errmsglen,
1317 "Not all the packets could be written to the file"
1318 " to which the capture was being saved\n"
1319 "(\"%s\") because there is no space left on the file system\n"
1320 "on which that file resides.",
1326 g_snprintf(errmsg, errmsglen,
1327 "Not all the packets could be written to the file"
1328 " to which the capture was being saved\n"
1329 "(\"%s\") because you are too close to, or over,"
1330 " your disk quota\n"
1331 "on the file system on which that file resides.",
1336 case WTAP_ERR_CANT_CLOSE:
1337 g_snprintf(errmsg, errmsglen,
1338 "The file to which the capture was being saved"
1339 " couldn't be closed for some unknown reason.");
1342 case WTAP_ERR_SHORT_WRITE:
1343 g_snprintf(errmsg, errmsglen,
1344 "Not all the packets could be written to the file"
1345 " to which the capture was being saved\n"
1352 g_snprintf(errmsg, errmsglen,
1353 "The file to which the capture was being saved\n"
1354 "(\"%s\") could not be closed: %s.",
1355 fname, wtap_strerror(err));
1357 g_snprintf(errmsg, errmsglen,
1358 "An error occurred while writing to the file"
1359 " to which the capture was being saved\n"
1361 fname, wtap_strerror(err));
1368 capture_loop_popup_errmsg(capture_options *capture_opts, const char *errmsg)
1370 if (capture_opts->capture_child) {
1371 /* This is the child process for a sync mode capture.
1372 Send the error message to our parent, so they can display a
1373 dialog box containing it. */
1374 sync_pipe_errmsg_to_parent(errmsg);
1376 /* Display the dialog box ourselves; there's no parent. */
1377 simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, "%s", errmsg);
1382 /* one packet was captured, process it */
1384 capture_loop_packet_cb(guchar *user, const struct pcap_pkthdr *phdr,
1387 struct wtap_pkthdr whdr;
1388 union wtap_pseudo_header pseudo_header;
1389 loop_data *ld = (loop_data *) user;
1392 /* if the user told us to stop after x packets, do we have enough? */
1394 if ((ld->packets_max > 0) && (ld->counts.total >= ld->packets_max))
1399 /* Convert from libpcap to Wiretap format.
1400 If that fails, set "ld->go" to FALSE, to stop the capture, and set
1401 "ld->err" to the error. */
1402 pd = wtap_process_pcap_packet(ld->wtap_linktype, phdr, pd, &pseudo_header,
1411 /* We're supposed to write the packet to a file; do so.
1412 If this fails, set "ld->go" to FALSE, to stop the capture, and set
1413 "ld->err" to the error. */
1414 if (!wtap_dump(ld->wtap_pdh, &whdr, &pseudo_header, pd, &err)) {
1420 switch (ld->wtap_linktype) {
1421 case WTAP_ENCAP_ETHERNET:
1422 capture_eth(pd, 0, whdr.caplen, &ld->counts);
1424 case WTAP_ENCAP_FDDI:
1425 case WTAP_ENCAP_FDDI_BITSWAPPED:
1426 capture_fddi(pd, whdr.caplen, &ld->counts);
1428 case WTAP_ENCAP_PRISM_HEADER:
1429 capture_prism(pd, 0, whdr.caplen, &ld->counts);
1431 case WTAP_ENCAP_TOKEN_RING:
1432 capture_tr(pd, 0, whdr.caplen, &ld->counts);
1434 case WTAP_ENCAP_NULL:
1435 capture_null(pd, whdr.caplen, &ld->counts);
1437 case WTAP_ENCAP_PPP:
1438 capture_ppp_hdlc(pd, 0, whdr.caplen, &ld->counts);
1440 case WTAP_ENCAP_RAW_IP:
1441 capture_raw(pd, whdr.caplen, &ld->counts);
1443 case WTAP_ENCAP_SLL:
1444 capture_sll(pd, whdr.caplen, &ld->counts);
1446 case WTAP_ENCAP_LINUX_ATM_CLIP:
1447 capture_clip(pd, whdr.caplen, &ld->counts);
1449 case WTAP_ENCAP_IEEE_802_11:
1450 case WTAP_ENCAP_IEEE_802_11_WITH_RADIO:
1451 capture_ieee80211(pd, 0, whdr.caplen, &ld->counts);
1453 case WTAP_ENCAP_CHDLC:
1454 capture_chdlc(pd, 0, whdr.caplen, &ld->counts);
1456 case WTAP_ENCAP_LOCALTALK:
1457 capture_llap(&ld->counts);
1459 case WTAP_ENCAP_ATM_PDUS:
1460 capture_atm(&pseudo_header, pd, whdr.caplen, &ld->counts);
1462 case WTAP_ENCAP_IP_OVER_FC:
1463 capture_ipfc(pd, whdr.caplen, &ld->counts);
1465 case WTAP_ENCAP_ARCNET:
1466 capture_arcnet(pd, whdr.caplen, &ld->counts, FALSE, TRUE);
1468 case WTAP_ENCAP_ARCNET_LINUX:
1469 capture_arcnet(pd, whdr.caplen, &ld->counts, TRUE, FALSE);
1471 case WTAP_ENCAP_APPLE_IP_OVER_IEEE1394:
1472 capture_ap1394(pd, 0, whdr.caplen, &ld->counts);
1474 /* XXX - some ATM drivers on FreeBSD might prepend a 4-byte ATM
1475 pseudo-header to DLT_ATM_RFC1483, with LLC header following;
1476 we might have to implement that at some point. */
1480 #endif /* HAVE_LIBPCAP */