plugins/docsis/packet-dccack.c

   1 /* packet-dccack.c
   2  * Routines for DCC Acknowledge Message  dissection
   3  * Copyright 2004, Darryl Hymel <darryl.hymel[AT]arrisi.com>
   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/exceptions.h>
  30
  31 #define DCCACK_KEY_SEQ_NUM 31
  32 #define DCCACK_HMAC_DIGEST 27
  33
  34 /* Initialize the protocol and registered fields */
  35 static int proto_docsis_dccack = -1;
  36
  37 static int hf_docsis_dccack_tran_id = -1;
  38 static int hf_docsis_dccack_key_seq_num = -1;
  39 static int hf_docsis_dccack_hmac_digest = -1;
  40
  41 /* Initialize the subtree pointers */
  42 static gint ett_docsis_dccack = -1;
  43
  44
  45 /* Code to actually dissect the packets */
  46 static void
  47 dissect_dccack (tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)
  48 {
  49   guint16 pos;
  50   guint8 type, length;
  51   proto_tree *dcc_tree;
  52   proto_item *dcc_item;
  53   guint16 len;
  54
  55   len = tvb_length_remaining (tvb, 0);
  56
  57   col_set_str(pinfo->cinfo, COL_INFO, "DCC-ACK Message: ");
  58
  59   if (tree)
  60     {
  61       dcc_item =
  62         proto_tree_add_protocol_format (tree, proto_docsis_dccack, tvb, 0,
  63                                         tvb_length_remaining (tvb, 0),
  64                                         "DCC-ACK Message");
  65       dcc_tree = proto_item_add_subtree (dcc_item, ett_docsis_dccack);
  66       proto_tree_add_item (dcc_tree, hf_docsis_dccack_tran_id, tvb, 0, 2, ENC_BIG_ENDIAN);
  67
  68       pos = 2;
  69       while (pos < len)
  70         {
  71           type = tvb_get_guint8 (tvb, pos++);
  72           length = tvb_get_guint8 (tvb, pos++);
  73           switch (type)
  74             {
  75             case DCCACK_KEY_SEQ_NUM:
  76               if (length == 1)
  77                 {
  78                   proto_tree_add_item (dcc_tree, hf_docsis_dccack_key_seq_num, tvb,
  79                                        pos, length, ENC_BIG_ENDIAN);
  80                 }
  81               else
  82                 {
  83                   THROW (ReportedBoundsError);
  84                 }
  85               break;
  86             case DCCACK_HMAC_DIGEST:
  87               if (length == 20)
  88                 {
  89                   proto_tree_add_item (dcc_tree, hf_docsis_dccack_hmac_digest, tvb,
  90                                        pos, length, ENC_NA);
  91                 }
  92               else
  93                 {
  94                   THROW (ReportedBoundsError);
  95                 }
  96               break;
  97             }                   /* switch(type) */
  98           pos = pos + length;
  99         }                       /* while (pos < len) */
 100     }                           /* if (tree) */
 101
 102 }
 103 /* Register the protocol with Wireshark */
 104
 105 /* this format is require because a script is used to build the C function
 106    that calls all the protocol registration.
 107 */
 108
 109
 110 void
 111 proto_register_docsis_dccack (void)
 112 {
 113 /* Setup list of header fields  See Section 1.6.1 for details*/
 114   static hf_register_info hf[] = {
 115     {&hf_docsis_dccack_tran_id ,
 116       {
 117       "Transaction ID",
 118       "docsis_dccack.tran_id",
 119       FT_UINT16, BASE_DEC, NULL, 0x0,
 120       NULL,
 121       HFILL
 122       }
 123     },
 124     {&hf_docsis_dccack_key_seq_num ,
 125       {
 126       "Auth Key Sequence Number",
 127       "docsis_dccack.key_seq_num",
 128       FT_UINT8, BASE_DEC, NULL, 0x0,
 129       NULL,
 130       HFILL
 131       }
 132     },
 133     {&hf_docsis_dccack_hmac_digest ,
 134       {
 135       "HMAC-DigestNumber",
 136       "docsis_dccack.hmac_digest",
 137       FT_BYTES, BASE_NONE, NULL, 0x0,
 138       NULL,
 139       HFILL
 140       }
 141     },
 142
 143   };
 144
 145 /* Setup protocol subtree array */
 146   static gint *ett[] = {
 147     &ett_docsis_dccack,
 148   };
 149
 150 /* Register the protocol name and description */
 151   proto_docsis_dccack =
 152     proto_register_protocol ("DOCSIS Downstream Channel Change Acknowledge",
 153                              "DOCSIS DCC-ACK", "docsis_dccack");
 154
 155 /* Required function calls to register the header fields and subtrees used */
 156   proto_register_field_array (proto_docsis_dccack, hf, array_length (hf));
 157   proto_register_subtree_array (ett, array_length (ett));
 158
 159   register_dissector ("docsis_dccack", dissect_dccack, proto_docsis_dccack);
 160 }
 161
 162
 163 /* If this dissector uses sub-dissector registration add a registration routine.
 164    This format is required because a script is used to find these routines and
 165    create the code that calls these routines.
 166 */
 167 void
 168 proto_reg_handoff_docsis_dccack (void)
 169 {
 170   dissector_handle_t docsis_dccack_handle;
 171
 172   docsis_dccack_handle = find_dissector ("docsis_dccack");
 173   dissector_add_uint ("docsis_mgmt", 0x19, docsis_dccack_handle);
 174
 175 }