epan/dissectors/packet-mac-lte-framed.c

   1 /* Routines for MAC LTE format files with context info as header.
   2  *
   3  * Martin Mathieson
   4  *
   5  * $Id$
   6  *
   7  * Wireshark - Network traffic analyzer
   8  * By Gerald Combs <gerald@wireshark.org>
   9  * Copyright 1998 Gerald Combs
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version 2
  14  * of the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  24  */
  25
  26 #include "config.h"
  27
  28 #include <epan/packet.h>
  29 #include <epan/wmem/wmem.h>
  30
  31 #include "packet-mac-lte.h"
  32
  33
  34 /* Initialize the protocol and registered fields. */
  35 static int proto_mac_lte_framed = -1;
  36
  37 extern int proto_mac_lte;
  38
  39 /* Main dissection function. */
  40 static void dissect_mac_lte_framed(tvbuff_t *tvb, packet_info *pinfo,
  41                                    proto_tree *tree)
  42 {
  43     gint                 offset = 0;
  44     struct mac_lte_info  *p_mac_lte_info;
  45     tvbuff_t             *mac_tvb;
  46     gboolean             infoAlreadySet = FALSE;
  47
  48     /* Need to find enabled mac-lte dissector */
  49     dissector_handle_t   mac_lte_handle = find_dissector("mac-lte");
  50     if (!mac_lte_handle) {
  51         return;
  52     }
  53
  54     /* Do this again on re-dissection to re-discover offset of actual PDU */
  55
  56     /* Needs to be at least as long as:
  57        - fixed header bytes
  58        - tag for data
  59        - at least one byte of MAC PDU payload */
  60     if ((size_t)tvb_length_remaining(tvb, offset) < (3+2)) {
  61         return;
  62     }
  63
  64     /* If redissecting, use previous info struct (if available) */
  65     p_mac_lte_info = (struct mac_lte_info*)p_get_proto_data(pinfo->fd, proto_mac_lte, 0);
  66     if (p_mac_lte_info == NULL) {
  67         /* Allocate new info struct for this frame */
  68         p_mac_lte_info = (struct mac_lte_info*)wmem_alloc0(wmem_file_scope(), sizeof(struct mac_lte_info));
  69         infoAlreadySet = FALSE;
  70     }
  71     else {
  72         infoAlreadySet = TRUE;
  73     }
  74
  75     /* Dissect the fields to populate p_mac_lte */
  76     if (!dissect_mac_lte_context_fields(p_mac_lte_info, tvb, &offset)) {
  77         return;
  78     }
  79
  80     /* Store info in packet (first time) */
  81     if (!infoAlreadySet) {
  82         p_add_proto_data(pinfo->fd, proto_mac_lte, 0, p_mac_lte_info);
  83     }
  84
  85     /**************************************/
  86     /* OK, now dissect as MAC LTE         */
  87
  88     /* Create tvb that starts at actual MAC PDU */
  89     mac_tvb = tvb_new_subset_remaining(tvb, offset);
  90     call_dissector_only(mac_lte_handle, mac_tvb, pinfo, tree, NULL);
  91 }
  92
  93 void proto_register_mac_lte_framed(void)
  94 {
  95     /* Register protocol. */
  96     proto_mac_lte_framed = proto_register_protocol("mac-lte-framed", "MAC-LTE-FRAMED", "mac-lte-framed");
  97
  98     /* Allow other dissectors to find this one by name. */
  99     register_dissector("mac-lte-framed", dissect_mac_lte_framed, proto_mac_lte_framed);
 100 }
 101