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

   1 /* Routines for MAC NR format files with context info as header.
   2  *
   3  * Based on mac-lte-framed.c
   4  *
   5  * Martin Mathieson
   6  * Pedro Alvarez
   7  *
   8  * Wireshark - Network traffic analyzer
   9  * By Gerald Combs <gerald@wireshark.org>
  10  * Copyright 1998 Gerald Combs
  11  *
  12  * SPDX-License-Identifier: GPL-2.0-or-later
  13  */
  14
  15 #include <epan/packet.h>
  16 #include <epan/proto_data.h>
  17
  18 #include "config.h"
  19 #include "packet-mac-nr.h"
  20
  21 void proto_register_mac_nr_framed(void);
  22
  23 /* Initialize the protocol and registered fields. */
  24 static int proto_mac_nr_framed;
  25
  26 extern int proto_mac_nr;
  27
  28 /* Main dissection function. */
  29 static int dissect_mac_nr_framed(tvbuff_t *tvb, packet_info *pinfo,
  30                                  proto_tree *tree, void *data _U_) {
  31     int offset = 0;
  32     struct mac_nr_info *p_mac_nr_info;
  33     tvbuff_t *mac_tvb;
  34     bool infoAlreadySet = false;
  35
  36     /* Need to find enabled mac-nr dissector */
  37     dissector_handle_t mac_nr_handle = find_dissector("mac-nr");
  38     if (!mac_nr_handle) {
  39         return 0;
  40     }
  41
  42     /* Do this again on re-dissection to re-discover offset of actual PDU */
  43
  44     /* Needs to be at least as long as:
  45        - fixed header bytes
  46        - tag for data
  47        - at least one byte of MAC PDU payload */
  48     if ((size_t)tvb_reported_length_remaining(tvb, offset) < (3 + 2)) {
  49         return 5;
  50     }
  51
  52     /* If redissecting, use previous info struct (if available) */
  53     p_mac_nr_info = (struct mac_nr_info *)p_get_proto_data(
  54         wmem_file_scope(), pinfo, proto_mac_nr, 0);
  55     if (p_mac_nr_info == NULL) {
  56         /* Allocate new info struct for this frame */
  57         p_mac_nr_info = wmem_new0(wmem_file_scope(), struct mac_nr_info);
  58     } else {
  59         infoAlreadySet = true;
  60     }
  61
  62     /* Dissect the fields to populate p_mac_nr */
  63     if (!dissect_mac_nr_context_fields(p_mac_nr_info, tvb, pinfo, tree,
  64                                        &offset)) {
  65         return offset;
  66     }
  67
  68     /* Store info in packet (first time) */
  69     if (!infoAlreadySet) {
  70         p_add_proto_data(wmem_file_scope(), pinfo, proto_mac_nr, 0,
  71                          p_mac_nr_info);
  72     }
  73
  74     /**************************************/
  75     /* OK, now dissect as MAC NR         */
  76
  77     /* Create tvb that starts at actual MAC PDU */
  78     mac_tvb = tvb_new_subset_remaining(tvb, offset);
  79     call_dissector_only(mac_nr_handle, mac_tvb, pinfo, tree, NULL);
  80     return tvb_captured_length(tvb);
  81 }
  82
  83 void proto_register_mac_nr_framed(void) {
  84     /* Register protocol. */
  85     proto_mac_nr_framed = proto_register_protocol(
  86         "mac-nr-framed", "MAC-NR-FRAMED", "mac-nr-framed");
  87
  88     /* Allow other dissectors to find this one by name. */
  89     register_dissector("mac-nr-framed", dissect_mac_nr_framed,
  90                        proto_mac_nr_framed);
  91 }
  92
  93 /*
  94  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  95  *
  96  * Local variables:
  97  * c-basic-offset: 4
  98  * tab-width: 8
  99  * indent-tabs-mode: nil
 100  * End:
 101  *
 102  * vi: set shiftwidth=4 tabstop=8 expandtab:
 103  * :indentSize=4:tabSize=8:noTabs=true:
 104  */