2 * packet tap interface 2002 Ronnie Sahlberg
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.
31 #ifdef HAVE_SYS_TYPES_H
32 # include <sys/types.h>
35 #ifdef HAVE_NETINET_IN_H
36 # include <netinet/in.h>
40 #include "epan/packet_info.h"
41 #include "epan/dfilter/dfilter.h"
44 static gboolean tapping_is_active=FALSE;
45 int num_tap_filters=0;
47 typedef struct _tap_dissector_t {
48 struct _tap_dissector_t *next;
51 static tap_dissector_t *tap_dissector_list=NULL;
54 * This is the list of free and used packets queued for a tap.
55 * It is implemented here explicitely instead of using GLib objects
56 * in order to be as fast as possible as we need to build and tear down the
57 * queued list at least once for each packet we see, thus we must be able
58 * to build and tear it down as fast as possible.
60 typedef struct _tap_packet_t {
63 const void *tap_specific_data;
66 #define TAP_PACKET_QUEUE_LEN 100
67 static tap_packet_t tap_packet_array[TAP_PACKET_QUEUE_LEN];
68 static guint tap_packet_index;
70 typedef struct _tap_listener_t {
71 struct _tap_listener_t *next;
80 static volatile tap_listener_t *tap_listener_queue=NULL;
82 /* structure to keep track of what tap listeners have registered
83 command-line arguments.
85 typedef struct _tap_cmd_arg {
86 struct _tap_cmd_arg *next;
88 void (*func)(char *arg);
90 static tap_cmd_arg *tap_cmd_arg_list=NULL;
92 /* structure to keep track of what taps have been specified on the
99 static GSList *taps_requested = NULL;
101 /* **********************************************************************
102 * Init routine only called from epan at application startup
103 * ********************************************************************** */
104 /* This function is called once when ethereal starts up and is used
105 to init any data structures we may need later.
115 /* **********************************************************************
116 * Function called from tap to register the tap's command-line argument
117 * and initialization routine
118 * ********************************************************************** */
120 register_tap_listener_cmd_arg(char *cmd, void (*func)(char *arg))
124 newtca=malloc(sizeof(tap_cmd_arg));
125 newtca->next=tap_cmd_arg_list;
126 tap_cmd_arg_list=newtca;
131 /* **********************************************************************
132 * Function called for a tap command-line argument
133 * ********************************************************************** */
135 process_tap_cmd_arg(char *optarg)
140 for(tca=tap_cmd_arg_list;tca;tca=tca->next){
141 if(!strncmp(tca->cmd,optarg,strlen(tca->cmd))){
142 tr=g_malloc(sizeof (tap_requested));
144 tr->arg=g_strdup(optarg);
145 taps_requested=g_slist_append(taps_requested, tr);
152 /* **********************************************************************
153 * Function to list all possible tap command-line arguments
154 * ********************************************************************** */
156 list_tap_cmd_args(void)
160 for(tca=tap_cmd_arg_list;tca;tca=tca->next){
161 fprintf(stderr," %s\n",tca->cmd);
165 /* **********************************************************************
166 * Function to process taps requested with command-line arguments
167 * ********************************************************************** */
169 start_requested_taps(void)
173 while(taps_requested){
174 tr=taps_requested->data;
175 (*tr->tca->func)(tr->arg);
178 taps_requested=g_slist_remove(taps_requested, tr);
182 /* **********************************************************************
183 * Functions called from dissector when made tappable
184 * ********************************************************************** */
185 /* the following two functions are used from dissectors to
186 1, register the ability to tap packets from this subdissector
187 2, push packets encountered by the subdissector to anyone tapping
190 /* This function registers that a dissector has the packet tap ability
191 available. The name parameter is the name of this tap and extensions can
192 use open_tap(char *name,... to specify that it wants to receive packets/
193 events from this tap.
195 This function is only to be called once, when the dissector initializes.
197 The return value from this call is later used as a parameter to the
198 tap_packet(unsinged int *tap_id,...
199 call so that the tap subsystem knows to which tap point this tapped
200 packet is associated.
203 register_tap(char *name)
205 tap_dissector_t *td, *tdl;
208 td=g_malloc(sizeof(tap_dissector_t));
210 td->name = g_strdup(name);
212 if(!tap_dissector_list){
213 tap_dissector_list=td;
216 for(i=2,tdl=tap_dissector_list;tdl->next;i++,tdl=tdl->next)
224 /* Everytime the dissector has finished dissecting a packet (and all
225 subdissectors have returned) and if the dissector has been made "tappable"
226 it will push some data to everyone tapping this layer by a call
227 to tap_queue_packet().
228 The first parameter is the tap_id returned by the register_tap()
229 call for this dissector (so the tap system can keep track of who it came
230 from and who is listening to it)
231 The second is the packet_info structure which many tap readers will find
233 The third argument is specific to each tap point or NULL if no additional
234 data is available to this tap. A tap point in say IP will probably want to
235 push the IP header structure here. Same thing for TCP and ONCRPC.
237 The pinfo and the specific pointer are what is supplied to every listener
238 in the read_callback() call made to every one currently listening to this
241 The tap reader is responsible to know how to parse any structure pointed
242 to by the tap specific data pointer.
245 tap_queue_packet(int tap_id, packet_info *pinfo, const void *tap_specific_data)
249 if(!tapping_is_active){
253 tpt=&tap_packet_array[tap_packet_index];
256 tpt->tap_specific_data=tap_specific_data;
264 /* **********************************************************************
265 * Functions used by file.c to drive the tap subsystem
266 * ********************************************************************** */
267 /* This function is used to delete/initialize the tap queue and prime an
268 epan_dissect_t with all the filters for tap listeners.
269 To free the tap queue, we just prepend the used queue to the free queue.
272 tap_queue_init(epan_dissect_t *edt)
276 /* nothing to do, just return */
277 if(!tap_listener_queue){
281 tapping_is_active=TRUE;
285 /* loop over all tap listeners and build the list of all
286 interesting hf_fields */
287 for(tl=(tap_listener_t *)tap_listener_queue;tl;tl=tl->next){
289 epan_dissect_prime_dfilter(edt, tl->code);
294 /* this function is called after a packet has been fully dissected to push the tapped
295 data to all extensions that has callbacks registered.
298 tap_push_tapped_queue(epan_dissect_t *edt)
304 /* nothing to do, just return */
305 if(!tapping_is_active){
309 tapping_is_active=FALSE;
311 /* nothing to do, just return */
312 if(!tap_packet_index){
316 /* loop over all tap listeners and call the listener callback
317 for all packets that match the filter. */
318 for(i=0;i<tap_packet_index;i++){
319 for(tl=(tap_listener_t *)tap_listener_queue;tl;tl=tl->next){
320 tp=&tap_packet_array[i];
321 if(tp->tap_id==tl->tap_id){
324 passed=dfilter_apply_edt(tl->code, edt);
326 if(passed && tl->packet){
327 tl->needs_redraw|=tl->packet(tl->tapdata, tp->pinfo, edt, tp->tap_specific_data);
334 /* This function is called when we need to reset all tap listeners, for example
335 when we open/start a new capture or if we need to rescan the packet list.
338 reset_tap_listeners(void)
342 for(tl=(tap_listener_t *)tap_listener_queue;tl;tl=tl->next){
344 tl->reset(tl->tapdata);
352 /* This function is called when we need to redraw all tap listeners, for example
353 when we open/start a new capture or if we need to rescan the packet list.
354 this one should be called from a low priority thread say once every 3 seconds
356 If draw_all is true, redraw all aplications regardless if they have
360 draw_tap_listeners(gboolean draw_all)
364 for(tl=(tap_listener_t *)tap_listener_queue;tl;tl=tl->next){
365 if(tl->needs_redraw || draw_all){
367 tl->draw(tl->tapdata);
376 /* **********************************************************************
377 * Functions used by tap to
378 * 1, register that a really simple extension is available for use by
380 * 2, start tapping from a subdissector
381 * 3, close an already open tap
382 * ********************************************************************** */
383 /* this function will return the tap_id for the specific protocol tap
384 or 0 if no such tap was found.
387 find_tap_id(char *name)
392 for(i=1,td=tap_dissector_list;td;i++,td=td->next) {
393 if(!strcmp(td->name,name)){
400 /* this function attaches the tap_listener to the named tap.
403 * non-NULL: error, return value points to GString containing error
407 register_tap_listener(char *tapname, void *tapdata, char *fstring, tap_reset_cb reset, tap_packet_cb packet, tap_draw_cb draw)
411 GString *error_string;
413 tap_id=find_tap_id(tapname);
415 error_string = g_string_new("");
416 g_string_sprintf(error_string, "Tap %s not found", tapname);
420 tl=g_malloc(sizeof(tap_listener_t));
424 if(!dfilter_compile(fstring, &tl->code)){
425 error_string = g_string_new("");
426 g_string_sprintf(error_string,
427 "Filter \"%s\" is invalid - %s",
428 fstring, dfilter_error_msg);
441 tl->next=(tap_listener_t *)tap_listener_queue;
443 tap_listener_queue=tl;
448 /* this function removes a tap listener
451 remove_tap_listener(void *tapdata)
453 tap_listener_t *tl=NULL,*tl2;
455 if(!tap_listener_queue){
459 if(tap_listener_queue->tapdata==tapdata){
460 tl=(tap_listener_t *)tap_listener_queue;
461 tap_listener_queue=tap_listener_queue->next;
463 for(tl2=(tap_listener_t *)tap_listener_queue;tl2->next;tl2=tl2->next){
464 if(tl2->next->tapdata==tapdata){
466 tl2->next=tl2->next->next;
475 dfilter_free(tl->code);
485 * Return TRUE if we have tap listeners, FALSE otherwise.
486 * Checking "num_tap_filters" isn't the right way to check whether we need
487 * to do any dissection in order to run taps, as not all taps necessarily
488 * have filters, and "num_tap_filters" is the number of tap filters, not
489 * the number of tap listeners; it's only the right way to check whether
490 * we need to build a protocol tree when doing dissection.
493 have_tap_listeners(void)
495 return tap_listener_queue != NULL;