/* capture.c * Routines for packet capture windows * * $Id$ * * Ethereal - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #ifdef HAVE_LIBPCAP #include #include #include #ifdef HAVE_FCNTL_H #include #endif #ifdef HAVE_IO_H # include #endif #include #include #include #include #include #include #include "file.h" #include "capture.h" #include "capture_sync.h" #include "capture_ui_utils.h" #include "util.h" #include "pcap-util.h" #include "alert_box.h" #include "simple_dialog.h" #include #include "conditions.h" #include "ringbuffer.h" #ifdef _WIN32 #include "capture-wpcap.h" #endif #include "ui_util.h" /* Win32 needs the O_BINARY flag for open() */ #ifndef O_BINARY #define O_BINARY 0 #endif static gboolean normal_do_capture(capture_options *capture_opts, gboolean is_tempfile); static void stop_capture_signal_handler(int signo); /* open the output file (temporary/specified name/ringbuffer) */ /* Returns TRUE if the file opened successfully, FALSE otherwise. */ static gboolean capture_open_output(capture_options *capture_opts, gboolean *is_tempfile) { char tmpname[128+1]; gchar *capfile_name; if (capture_opts->save_file != NULL) { /* If the Sync option is set, we return to the caller while the capture * is in progress. Therefore we need to take a copy of save_file in * case the caller destroys it after we return. */ capfile_name = g_strdup(capture_opts->save_file); if (capture_opts->multi_files_on) { /* ringbuffer is enabled */ capture_opts->save_file_fd = ringbuf_init(capfile_name, (capture_opts->has_ring_num_files) ? capture_opts->ring_num_files : 0); } else { /* Try to open/create the specified file for use as a capture buffer. */ capture_opts->save_file_fd = open(capfile_name, O_RDWR|O_BINARY|O_TRUNC|O_CREAT, 0600); } *is_tempfile = FALSE; } else { /* Choose a random name for the temporary capture buffer */ capture_opts->save_file_fd = create_tempfile(tmpname, sizeof tmpname, "ether"); capfile_name = g_strdup(tmpname); *is_tempfile = TRUE; } /* did we fail to open the output file? */ if (capture_opts->save_file_fd == -1) { if (*is_tempfile) { simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, "The temporary file to which the capture would be saved (\"%s\") " "could not be opened: %s.", capfile_name, strerror(errno)); } else { if (capture_opts->multi_files_on) { ringbuf_error_cleanup(); } open_failure_alert_box(capfile_name, errno, TRUE); } g_free(capfile_name); return FALSE; } if(capture_opts->save_file != NULL) { g_free(capture_opts->save_file); } capture_opts->save_file = capfile_name; /* capture_opts.save_file is "g_free"ed later, which is equivalent to "g_free(capfile_name)". */ return TRUE; } /* close the output file (NOT the capture file) */ static void capture_close_output(capture_options *capture_opts) { if (capture_opts->multi_files_on) { ringbuf_free(); } else { g_free(capture_opts->save_file); } capture_opts->save_file = NULL; } /* Open a specified file, or create a temporary file, and start a capture to the file in question. */ /* Returns TRUE if the capture starts successfully, FALSE otherwise. */ gboolean do_capture(capture_options *capture_opts) { gboolean is_tempfile; gboolean ret; /* open the new output file (temporary/specified name/ringbuffer) */ if(!capture_open_output(capture_opts, &is_tempfile)) { return FALSE; } /* close the currently loaded capture file */ cf_close(capture_opts->cf); /* We could simply use TRUE for this expression now, this will work for all * captures except for some of the multiple files options, as these capture * options currently cannot be passed through the command line to the * capture child. * * If this is fixed, we could always use the sync mode, throwing away the * normal mode completely and doing some more cleanup. */ /* if (TRUE) {*/ if (capture_opts->sync_mode) { /* sync mode: do the capture in a child process */ ret = sync_pipe_do_capture(capture_opts, is_tempfile); /* capture is still running */ cf_callback_invoke(cf_cb_live_capture_prepare, capture_opts); } else { /* normal mode: do the capture synchronously */ cf_callback_invoke(cf_cb_live_capture_prepare, capture_opts); ret = normal_do_capture(capture_opts, is_tempfile); /* capture is finished here */ } return ret; } /* we've succeeded a capture, try to read it into a new capture file */ gboolean capture_read(capture_options *capture_opts, gboolean is_tempfile, gboolean drops_known, guint32 drops) { int err; /* Capture succeeded; attempt to read in the capture file. */ if (cf_open(capture_opts->cf, capture_opts->save_file, is_tempfile, &err) != CF_OK) { /* We're not doing a capture any more, so we don't have a save file. */ return FALSE; } /* Set the read filter to NULL. */ /* XXX - this is odd here, try to put it somewhere, where it fits better */ cf_set_rfcode(capture_opts->cf, NULL); /* Get the packet-drop statistics. XXX - there are currently no packet-drop statistics stored in libpcap captures, and that's what we're reading. At some point, we will add support in Wiretap to return packet-drop statistics for capture file formats that store it, and will make "cf_read()" get those statistics from Wiretap. We clear the statistics (marking them as "not known") in "cf_open()", and "cf_read()" will only fetch them and mark them as known if Wiretap supplies them, so if we get the statistics now, after calling "cf_open()" but before calling "cf_read()", the values we store will be used by "cf_read()". If a future libpcap capture file format stores the statistics, we'll put them into the capture file that we write, and will thus not have to set them here - "cf_read()" will get them from the file and use them. */ if (drops_known) { cf_set_drops_known(capture_opts->cf, TRUE); /* XXX - on some systems, libpcap doesn't bother filling in "ps_ifdrop" - it doesn't even set it to zero - so we don't bother looking at it. Ideally, libpcap would have an interface that gave us several statistics - perhaps including various interface error statistics - and would tell us which of them it supplies, allowing us to display only the ones it does. */ cf_set_drops(capture_opts->cf, drops); } switch (cf_read(capture_opts->cf)) { case CF_READ_OK: case CF_READ_ERROR: /* Just because we got an error, that doesn't mean we were unable to read any of the file; we handle what we could get from the file. */ break; case CF_READ_ABORTED: /* Exit by leaving the main loop, so that any quit functions we registered get called. */ main_window_nested_quit(); return FALSE; } /* if we didn't captured even a single packet, close the file again */ if(cf_packet_count(capture_opts->cf) == 0) { simple_dialog(ESD_TYPE_INFO, ESD_BTN_OK, "%sNo packets captured!%s\n\n" "As no data was captured, closing the %scapture file!", simple_dialog_primary_start(), simple_dialog_primary_end(), (cf_is_tempfile(capture_opts->cf)) ? "temporary " : ""); cf_close(capture_opts->cf); } return TRUE; } /* start a normal capture session */ static gboolean normal_do_capture(capture_options *capture_opts, gboolean is_tempfile) { gboolean succeeded; gboolean stats_known; struct pcap_stat stats; /* Not sync mode. */ succeeded = capture_loop_start(capture_opts, &stats_known, &stats); if (capture_opts->quit_after_cap) { /* DON'T unlink the save file. Presumably someone wants it. */ main_window_exit(); } if (succeeded) { /* We succeed in doing the capture, try to read it in. */ succeeded = capture_read(capture_opts, is_tempfile, stats_known, stats.ps_drop); } /* wether the capture suceeded or not, we have to close the output file here */ capture_close_output(capture_opts); return succeeded; } static void stop_capture_signal_handler(int signo _U_) { capture_loop_stop(); } int capture_child_start(capture_options *capture_opts, gboolean *stats_known, struct pcap_stat *stats) { gchar *err_msg; g_assert(capture_opts->capture_child); #ifndef _WIN32 /* * Catch SIGUSR1, so that we exit cleanly if the parent process * kills us with it due to the user selecting "Capture->Stop". */ signal(SIGUSR1, stop_capture_signal_handler); #endif /* parent must have send us a file descriptor for the opened output file */ if (capture_opts->save_file_fd == -1) { /* send this to the standard output as something our parent should put in an error message box */ err_msg = g_strdup_printf("%s: \"-W\" flag not specified (internal error)\n", CHILD_NAME); sync_pipe_errmsg_to_parent(err_msg); g_free(err_msg); return FALSE; } return capture_loop_start(capture_opts, stats_known, stats); } void capture_stop(capture_options *capture_opts) { /* stop the capture child, if we have one */ if (!capture_opts->capture_child) { sync_pipe_stop(capture_opts); } /* stop the capture loop */ capture_loop_stop(); } void capture_kill_child(capture_options *capture_opts) { /* kill the capture child, if we have one */ if (!capture_opts->capture_child) { sync_pipe_kill(capture_opts); } } #endif /* HAVE_LIBPCAP */