epan/tap.h

   1 /* tap.h
   2  * packet tap interface   2002 Ronnie Sahlberg
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  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.
  14  *
  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.
  19  *
  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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 #ifndef __TAP_H__
  26 #define __TAP_H__
  27
  28 #include <epan/epan.h>
  29 #include "ws_symbol_export.h"
  30
  31 #ifdef __cplusplus
  32 extern "C" {
  33 #endif /* __cplusplus */
  34
  35 typedef void (*tap_reset_cb)(void *tapdata);
  36 typedef gboolean (*tap_packet_cb)(void *tapdata, packet_info *pinfo, epan_dissect_t *edt, const void *data);
  37 typedef void (*tap_draw_cb)(void *tapdata);
  38
  39 /**
  40  * Flags to indicate what a tap listener's packet routine requires.
  41  */
  42 #define TL_REQUIRES_NOTHING     0x00000000      /**< nothing */
  43 #define TL_REQUIRES_PROTO_TREE  0x00000001      /**< full protocol tree */
  44 #define TL_REQUIRES_COLUMNS     0x00000002      /**< columns */
  45 /** Flags to indicate what the tap listener does */
  46 #define TL_IS_DISSECTOR_HELPER  0x00000004      /**< tap helps a dissector do work
  47                                                  ** but does not, itself, require dissection */
  48
  49 extern void tap_init(void);
  50
  51 /** This function registers that a dissector has the packet tap ability
  52  *  available.  The name parameter is the name of this tap and extensions can
  53  *  use open_tap(char *name,... to specify that it wants to receive packets/
  54  *  events from this tap.
  55  *
  56  *  This function is only to be called once, when the dissector initializes.
  57  *
  58  *  The return value from this call is later used as a parameter to the
  59  *  tap_packet(unsigned int *tap_id,...
  60  *  call so that the tap subsystem knows to which tap point this tapped
  61  *  packet is associated.
  62  */
  63 WS_DLL_PUBLIC int register_tap(const char *name);
  64
  65 /** This function will return the tap_id for the specific protocol tap
  66  *  or 0 if no such tap was found.
  67  */
  68 WS_DLL_PUBLIC int find_tap_id(const char *name);
  69
  70 /** Everytime the dissector has finished dissecting a packet (and all
  71  *  subdissectors have returned) and if the dissector has been made "tappable"
  72  *  it will push some data to everyone tapping this layer by a call
  73  *  to tap_queue_packet().
  74  *  The first parameter is the tap_id returned by the register_tap()
  75  *  call for this dissector (so the tap system can keep track of who it came
  76  *  from and who is listening to it)
  77  *  The second is the packet_info structure which many tap readers will find
  78  *  interesting.
  79  *  The third argument is specific to each tap point or NULL if no additional
  80  *  data is available to this tap.  A tap point in say IP will probably want to
  81  *  push the IP header structure here. Same thing for TCP and ONCRPC.
  82  *
  83  *  The pinfo and the specific pointer are what is supplied to every listener
  84  *  in the read_callback() call made to every one currently listening to this
  85  *  tap.
  86  *
  87  *  The tap reader is responsible to know how to parse any structure pointed
  88  *  to by the tap specific data pointer.
  89  */
  90 WS_DLL_PUBLIC void tap_queue_packet(int tap_id, packet_info *pinfo, const void *tap_specific_data);
  91
  92 /** Functions used by file.c to drive the tap subsystem */
  93 WS_DLL_PUBLIC void tap_build_interesting(epan_dissect_t *edt);
  94
  95 /** This function is used to delete/initialize the tap queue and prime an
  96  *  epan_dissect_t with all the filters for tap listeners.
  97  *  To free the tap queue, we just prepend the used queue to the free queue.
  98  */
  99 extern void tap_queue_init(epan_dissect_t *edt);
 100
 101 /** this function is called after a packet has been fully dissected to push the tapped
 102  *  data to all extensions that has callbacks registered.
 103  */
 104
 105 extern void tap_push_tapped_queue(epan_dissect_t *edt);
 106
 107 /** This function is called after a packet has been fully dissected to push the tapped
 108  *  data to all extensions that has callbacks registered.
 109  */
 110
 111 WS_DLL_PUBLIC void reset_tap_listeners(void);
 112
 113 /** This function is called when we need to redraw all tap listeners, for example
 114  * when we open/start a new capture or if we need to rescan the packet list.
 115  * It should be called from a low priority thread say once every 3 seconds
 116  *
 117  * If draw_all is true, redraw all aplications regardless if they have
 118  * changed or not.
 119  */
 120 WS_DLL_PUBLIC void draw_tap_listeners(gboolean draw_all);
 121
 122 /** this function attaches the tap_listener to the named tap.
 123  * function returns :
 124  *     NULL: ok.
 125  * non-NULL: error, return value points to GString containing error
 126  *           message.
 127  * @param tapname    The name of the tap we want to listen to.
 128  * @param tapdata    is the instance identifier. The tap system uses the value of this
 129  *                   pointer to distinguish between different instances of a tap.
 130  *                   Just make sure that it is unique by letting it be the pointer to a struct
 131  *                   holding all state variables. If you want to allow multiple concurrent
 132  *                   instances, just put ALL state variables inside a struct allocated by
 133  *                   g_malloc() and use that pointer.
 134  * @param fstring    is a pointer to a filter string.
 135  *                   If this is NULL, then the tap system will provide ALL packets passing the
 136  *                   tapped protocol to your listener.
 137  *                   If you specify a filter string here the tap system will first try
 138  *                   to apply this string to the packet and then only pass those packets that
 139  *                   matched the filter to your listener.
 140  *                   The syntax for the filter string is identical to normal display filters.
 141  *
 142  *                   NOTE: Specifying filter strings will have a significant performance impact
 143  *                   on your application and Wireshark. If possible it is MUCH better to take
 144  *                   unfiltered data and just filter it yourself in the packet-callback than
 145  *                   to specify a filter string.
 146  *                   ONLY use a filter string if no other option exist.
 147  *
 148  * @param flags      is a set of flags for the tap listener.  The flags that can be set are:
 149  *
 150  *                      TL_REQUIRES_PROTO_TREE
 151  *
 152  *                      set if your tap listener "packet" routine requires a protocol
 153  *                      tree to be built.  It will require a protocol tree to be
 154  *                      built if either
 155  *
 156  *                              1) it looks at the protocol tree in edt->tree
 157  *
 158  *                      or
 159  *
 160  *                              2) the tap-specific data passed to it is constructed only if
 161  *                                 the protocol tree is being built.
 162  *
 163  *                      TL_REQUIRES_COLUMNS
 164  *
 165  *                      set if your tap listener "packet" routine requires the column
 166  *                      strings to be constructed.
 167  *
 168  *                       If no flags are needed, use TL_REQUIRES_NOTHING.
 169  *
 170  * @param tap_reset  void (*reset)(void *tapdata)
 171  *                   This callback is called whenever Wireshark wants to inform your
 172  *                   listener that it is about to start [re]reading a capture file or a new capture
 173  *                   from an interface and that your application should reset any state it has
 174  *                   in the *tapdata instance.
 175  * @param tap_packet gboolean (*packet)(void *tapdata, packet_info *pinfo, epan_dissect_t *edt, const void *data)
 176  *                   This callback is used whenever a new packet has arrived at the tap and that
 177  *                   it has passed the filter (if there were a filter).
 178  *                   The *data structure type is specific to each tap.
 179  *                   This function returns an gboolean and it should return
 180  *                    TRUE, if the data in the packet caused state to be updated
 181  *                          (and thus a redraw of the window would later be required)
 182  *                    FALSE, if we don't need to redraw the window.
 183  *                   NOTE: that (*packet) should be as fast and efficient as possible. Use this
 184  *                   function ONLY to store data for later and do the CPU-intensive processing
 185  *                   or GUI updates down in (*draw) instead.
 186  * @param tap_draw   void (*draw)(void *tapdata)
 187  *                   This callback is used when Wireshark wants your application to redraw its
 188  *                   output. It will usually not be called unless your application has received
 189  *                   new data through the (*packet) callback.
 190  *                   On some ports of Wireshark (gtk2) (*draw) will be called asynchronously
 191  *                   from a separate thread up to once every 2-3 seconds.
 192  *                   On other ports it might only be called once when the capture is finished
 193  *                   or the file has been [re]read completely.
 194  */
 195
 196 WS_DLL_PUBLIC GString *register_tap_listener(const char *tapname, void *tapdata,
 197     const char *fstring, guint flags, tap_reset_cb tap_reset,
 198     tap_packet_cb tap_packet, tap_draw_cb tap_draw);
 199
 200 /** This function sets a new dfilter to a tap listener */
 201 WS_DLL_PUBLIC GString *set_tap_dfilter(void *tapdata, const char *fstring);
 202
 203 /** this function removes a tap listener */
 204 WS_DLL_PUBLIC void remove_tap_listener(void *tapdata);
 205
 206 /**
 207  * Return TRUE if we have one or more tap listeners that require dissection,
 208  * FALSE otherwise.
 209  */
 210 WS_DLL_PUBLIC gboolean tap_listeners_require_dissection(void);
 211
 212 /** Returns TRUE there is an active tap listener for the specified tap id. */
 213 extern gboolean have_tap_listener(int tap_id);
 214
 215 /** Return TRUE if we have any tap listeners with filters, FALSE otherwise. */
 216 WS_DLL_PUBLIC gboolean have_filtering_tap_listeners(void);
 217
 218 /**
 219  * Get the union of all the flags for all the tap listeners; that gives
 220  * an indication of whether the protocol tree, or the columns, are
 221  * required by any taps.
 222  */
 223 WS_DLL_PUBLIC guint union_of_tap_listener_flags(void);
 224
 225 /** This function can be used by a dissector to fetch any tapped data before
 226  * returning.
 227  * This can be useful if one wants to extract the data inside dissector  BEFORE
 228  * it exists as an alternative to the callbacks that are all called AFTER the
 229  * dissection has completed.
 230  *
 231  * Example: SMB2 uses this mechanism to extract the data tapped from NTLMSSP
 232  * containing the account and domain names before exiting.
 233  * Note that the SMB2 tap listener specifies all three callbacks as NULL.
 234  *
 235  * Beware: when using this mechanism to extract the tapped data you can not
 236  * use "filters" and should specify the "filter" as NULL when registering
 237  * the tap listener.
 238  */
 239 WS_DLL_PUBLIC const void *fetch_tapped_data(int tap_id, int idx);
 240
 241 #ifdef __cplusplus
 242 }
 243 #endif /* __cplusplus */
 244
 245 #endif /* __TAP_H__ */