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  * Wireshark - Network traffic analyzer
   6  * By Gerald Combs <gerald@wireshark.org>
   7  * Copyright 1998 Gerald Combs
   8  *
   9  * SPDX-License-Identifier: GPL-2.0-or-later
  10  */
  11
  12 #include "config.h"
  13
  14 #include <epan/packet.h>
  15 #include <epan/proto_data.h>
  16 #include "packet-mac-lte.h"
  17
  18 void proto_register_mac_lte_framed(void);
  19
  20 /* Initialize the protocol and registered fields. */
  21 static int proto_mac_lte_framed;
  22
  23 extern int proto_mac_lte;
  24
  25 /* Main dissection function. */
  26 static int dissect_mac_lte_framed(tvbuff_t *tvb, packet_info *pinfo,
  27                                    proto_tree *tree, void* data _U_)
  28 {
  29     int                  offset = 0;
  30     struct mac_lte_info  *p_mac_lte_info;
  31     tvbuff_t             *mac_tvb;
  32     bool                 infoAlreadySet = false;
  33
  34     /* Need to find enabled mac-lte dissector */
  35     dissector_handle_t   mac_lte_handle = find_dissector("mac-lte");
  36     if (!mac_lte_handle) {
  37         return 0;
  38     }
  39
  40     /* Do this again on re-dissection to re-discover offset of actual PDU */
  41
  42     /* Needs to be at least as long as:
  43        - fixed header bytes
  44        - tag for data
  45        - at least one byte of MAC PDU payload */
  46     if ((size_t)tvb_reported_length_remaining(tvb, offset) < (3+2)) {
  47         return 5;
  48     }
  49
  50     /* If redissecting, use previous info struct (if available) */
  51     p_mac_lte_info = (struct mac_lte_info*)p_get_proto_data(wmem_file_scope(), pinfo, proto_mac_lte, 0);
  52     if (p_mac_lte_info == NULL) {
  53         /* Allocate new info struct for this frame */
  54         p_mac_lte_info = wmem_new0(wmem_file_scope(), struct mac_lte_info);
  55         infoAlreadySet = false;
  56     }
  57     else {
  58         infoAlreadySet = true;
  59     }
  60
  61     /* Dissect the fields to populate p_mac_lte */
  62     if (!dissect_mac_lte_context_fields(p_mac_lte_info, tvb, pinfo, tree, &offset)) {
  63         return offset;
  64     }
  65
  66     /* Store info in packet (first time) */
  67     if (!infoAlreadySet) {
  68         p_add_proto_data(wmem_file_scope(), pinfo, proto_mac_lte, 0, p_mac_lte_info);
  69     }
  70
  71     /**************************************/
  72     /* OK, now dissect as MAC LTE         */
  73
  74     /* Create tvb that starts at actual MAC PDU */
  75     mac_tvb = tvb_new_subset_remaining(tvb, offset);
  76     call_dissector_only(mac_lte_handle, mac_tvb, pinfo, tree, NULL);
  77     return tvb_captured_length(tvb);
  78 }
  79
  80 void proto_register_mac_lte_framed(void)
  81 {
  82     /* Register protocol. */
  83     proto_mac_lte_framed = proto_register_protocol("mac-lte-framed", "MAC-LTE-FRAMED", "mac-lte-framed");
  84
  85     /* Allow other dissectors to find this one by name. */
  86     register_dissector("mac-lte-framed", dissect_mac_lte_framed, proto_mac_lte_framed);
  87 }
  88
  89 /*
  90  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  91  *
  92  * Local variables:
  93  * c-basic-offset: 4
  94  * tab-width: 8
  95  * indent-tabs-mode: nil
  96  * End:
  97  *
  98  * vi: set shiftwidth=4 tabstop=8 expandtab:
  99  * :indentSize=4:tabSize=8:noTabs=true:
 100  */