2 * Do the low-level work of a capture
6 * Wireshark - Network traffic analyzer
7 * By Gerald Combs <gerald@wireshark.org>
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 * Do the low-level work of a capture.
32 #ifndef __CAPTURE_LOOP_H__
33 #define __CAPTURE_LOOP_H__
37 * Get information about libpcap format from "wiretap/libpcap.h".
38 * XXX - can we just use pcap_open_offline() to read the pipe?
40 #include "wiretap/libpcap.h"
43 /** Do the low-level work of a capture.
44 * Returns TRUE if it succeeds, FALSE otherwise. */
45 extern int capture_loop_start(capture_options *capture_opts, gboolean *stats_known, struct pcap_stat *stats);
47 /** Stop a low-level capture (stops the capture child). */
48 extern void capture_loop_stop(void);
51 /*** the following is internal only (should be moved to capture_loop_int.h) ***/
54 #ifndef HAVE_PCAP_BREAKLOOP
56 * We don't have pcap_breakloop(), which is the only way to ensure that
57 * pcap_dispatch(), pcap_loop(), or even pcap_next() or pcap_next_ex()
58 * won't, if the call to read the next packet or batch of packets is
59 * is interrupted by a signal on UN*X, just go back and try again to
62 * On UN*X, we catch SIGUSR1 as a "stop capturing" signal, and, in
63 * the signal handler, set a flag to stop capturing; however, without
64 * a guarantee of that sort, we can't guarantee that we'll stop capturing
65 * if the read will be retried and won't time out if no packets arrive.
67 * Therefore, on at least some platforms, we work around the lack of
68 * pcap_breakloop() by doing a select() on the pcap_t's file descriptor
69 * to wait for packets to arrive, so that we're probably going to be
70 * blocked in the select() when the signal arrives, and can just bail
71 * out of the loop at that point.
73 * However, we don't want to that on BSD (because "select()" doesn't work
74 * correctly on BPF devices on at least some releases of some flavors of
75 * BSD), and we don't want to do it on Windows (because "select()" is
76 * something for sockets, not for arbitrary handles). (Note that "Windows"
77 * here includes Cygwin; even in its pretend-it's-UNIX environment, we're
78 * using WinPcap, not a UNIX libpcap.)
80 * Fortunately, we don't need to do it on BSD, because the libpcap timeout
81 * on BSD times out even if no packets have arrived, so we'll eventually
82 * exit pcap_dispatch() with an indication that no packets have arrived,
83 * and will break out of the capture loop at that point.
85 * On Windows, we can't send a SIGUSR1 to stop capturing, so none of this
86 * applies in any case.
88 * XXX - the various BSDs appear to define BSD in <sys/param.h>; we don't
89 * want to include it if it's not present on this platform, however.
91 # if !defined(__FreeBSD__) && !defined(__NetBSD__) && !defined(__OpenBSD__) && \
92 !defined(__bsdi__) && !defined(__APPLE__) && !defined(_WIN32) && \
94 # define MUST_DO_SELECT
95 # endif /* avoid select */
96 #endif /* HAVE_PCAP_BREAKLOOP */
98 typedef void (*capture_packet_cb_fct)(u_char *, const struct pcap_pkthdr *, const u_char *);
101 /* moved from capture_loop.c here, so we can combine it (and the related functions) with tshark */
102 /* XXX - should be moved back to capture_loop.c */
103 /* E: capture_loop.c only (Wireshark/dumpcap) T: tshark only */
104 typedef struct _loop_data {
106 gboolean go; /* TRUE as long as we're supposed to keep capturing */
107 int err; /* E: if non-zero, error seen while capturing */
108 gint packet_count; /* Number of packets we have already captured */
109 gint packet_max; /* E: Number of packets we're supposed to capture - 0 means infinite */
111 jmp_buf stopenv; /* T: starting point of loop (jump back this point on SIG...) */
113 char *save_file; /* T: Name of file to which we're writing */
114 capture_packet_cb_fct packet_cb; /* callback for a single captured packet */
116 /* pcap "input file" */
117 pcap_t *pcap_h; /* pcap handle */
118 gboolean pcap_err; /* E: TRUE if error from pcap */
119 #ifdef MUST_DO_SELECT
120 int pcap_fd; /* pcap file descriptor */
123 /* capture pipe (unix only "input file") */
124 gboolean from_cap_pipe; /* TRUE if we are capturing data from a capture pipe */
126 struct pcap_hdr cap_pipe_hdr; /* ? */
127 struct pcaprec_modified_hdr cap_pipe_rechdr; /* ? */
128 int cap_pipe_fd; /* the file descriptor of the capture pipe */
129 gboolean cap_pipe_modified; /* TRUE if data in the pipe uses modified pcap headers */
130 gboolean cap_pipe_byte_swapped; /* TRUE if data in the pipe is byte swapped */
131 unsigned int cap_pipe_bytes_to_read;/* Used by cap_pipe_dispatch */
132 unsigned int cap_pipe_bytes_read; /* Used by cap_pipe_dispatch */
134 STATE_EXPECT_REC_HDR,
139 enum { PIPOK, PIPEOF, PIPERR, PIPNEXIST } cap_pipe_err;
152 /** init the capture filter */
155 INITFILTER_BAD_FILTER,
156 INITFILTER_OTHER_ERROR
157 } initfilter_status_t;
159 extern initfilter_status_t
160 capture_loop_init_filter(pcap_t *pcap_h, gboolean from_cap_pipe, const gchar * iface, gchar * cfilter);
165 cap_pipe_dispatch(loop_data *, guchar *, char *, int);
170 capture_loop_open_input(capture_options *capture_opts, loop_data *ld,
171 char *errmsg, size_t errmsg_len,
172 char *secondary_errmsg, size_t secondary_errmsg_len);
175 capture_loop_open_output(capture_options *capture_opts, int *save_file_fd, char *errmsg, int errmsg_len);
178 capture_loop_init_output(capture_options *capture_opts, int save_file_fd, loop_data *ld, char *errmsg, int errmsg_len);
181 capture_loop_close_output(capture_options *capture_opts, loop_data *ld, int *err_close);
184 * Routines called by the capture loop code to report things.
187 /** Report a new capture file having been opened. */
189 report_new_capture_file(const char *filename);
191 /** Report a number of new packets captured. */
193 report_packet_count(int packet_count);
195 /** Report the packet drops once the capture finishes. */
197 report_packet_drops(int drops);
199 /** Report an error in the capture. */
201 report_capture_error(const char *error_msg, const char *secondary_error_msg);
203 /** Report an error with a capture filter. */
205 report_cfilter_error(const char *cfilter, const char *errmsg);
208 #endif /* capture_loop.h */