epan/dissectors/packet-srp.c

   1 /* packet-srp.c
   2  * Routines for H.324/SRP dissection
   3  * 2004 Richard van der Hoff <richardv@mxtelecom.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 <glib.h>
  29 #include <epan/packet.h>
  30 #include <epan/bitswap.h>
  31 #include <epan/circuit.h>
  32 #include <epan/stream.h>
  33 #include <epan/crc16-tvb.h>
  34
  35 /* Wireshark ID of the protocols */
  36 static int proto_srp = -1;
  37 static int proto_ccsrl = -1;
  38
  39 /* The following hf_* variables are used to hold the Wireshark IDs of
  40  * our header fields; they are filled out when we call
  41  * proto_register_field_array() in proto_register_srp()
  42  */
  43 static int hf_srp_header = -1;
  44 static int hf_srp_seqno = -1;
  45 static int hf_srp_crc = -1;
  46 static int hf_srp_crc_bad = -1;
  47 static int hf_ccsrl_ls = -1;
  48
  49 /* These are the ids of the subtrees that we may be creating */
  50 static gint ett_srp = -1;
  51 static gint ett_ccsrl = -1;
  52
  53 static dissector_handle_t ccsrl_handle;
  54 static dissector_handle_t h245dg_handle;
  55
  56 /*****************************************************************************/
  57 #define SRP_SRP_COMMAND 249
  58 #define SRP_SRP_RESPONSE 251
  59 #define SRP_NSRP_RESPONSE 247
  60
  61 static const value_string srp_frame_types[] = {
  62   {SRP_SRP_COMMAND, "SRP command"},
  63   {SRP_SRP_RESPONSE, "SRP response"},
  64   {SRP_NSRP_RESPONSE, "NSRP response"},
  65   {0,NULL}
  66 };
  67
  68 static const value_string ccsrl_ls_vals[] = {
  69   {0xFF, "Yes"},
  70   {0x00, "No"},
  71   {0,NULL}
  72 };
  73
  74 /*****************************************************************************/
  75
  76 static void dissect_ccsrl(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)
  77 {
  78     proto_item *ccsrl_item;
  79     proto_tree *ccsrl_tree=NULL;
  80     guint8 lastseg = tvb_get_guint8(tvb,0);
  81     tvbuff_t *next_tvb;
  82
  83     /* add the 'ccsrl' tree to the main tree */
  84     if (tree) {
  85         ccsrl_item = proto_tree_add_item (tree, proto_ccsrl, tvb, 0, -1, ENC_NA);
  86         ccsrl_tree = proto_item_add_subtree (ccsrl_item, ett_ccsrl);
  87         proto_tree_add_uint(ccsrl_tree,hf_ccsrl_ls,tvb,0,1,lastseg);
  88     }
  89
  90     /* XXX add support for reassembly of fragments */
  91
  92     /* XXX currently, we always dissect as H245. It's not necessarily
  93         that though.
  94     */
  95     next_tvb = tvb_new_subset_remaining(tvb, 1);
  96     call_dissector( h245dg_handle, next_tvb, pinfo, ccsrl_tree );
  97 }
  98
  99 static void dissect_srp_command(tvbuff_t * tvb, packet_info * pinfo, proto_tree * srp_tree)
 100 {
 101     tvbuff_t *next_tvb;
 102     guint payload_len;
 103
 104     if( srp_tree )
 105         proto_tree_add_item(srp_tree,hf_srp_seqno,tvb,1,1,ENC_BIG_ENDIAN);
 106
 107     payload_len = tvb_reported_length_remaining(tvb,4);
 108     next_tvb = tvb_new_subset(tvb, 2, payload_len, payload_len );
 109
 110     /* XXX currently, we always dissect as CCSRL. It's only that in
 111      * H324/Annex C though.
 112      */
 113     call_dissector(ccsrl_handle, next_tvb, pinfo, srp_tree );
 114 }
 115
 116 static void dissect_srp (tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree)
 117 {
 118     proto_item *srp_item = NULL;
 119     proto_tree *srp_tree = NULL;
 120     proto_item *hidden_item;
 121
 122     guint8 header = tvb_get_guint8(tvb,0);
 123
 124     /* add the 'srp' tree to the main tree */
 125     if (tree) {
 126         srp_item = proto_tree_add_item (tree, proto_srp, tvb, 0, -1, ENC_NA);
 127         srp_tree = proto_item_add_subtree (srp_item, ett_srp);
 128         proto_tree_add_uint(srp_tree,hf_srp_header,tvb,0,1,header);
 129     }
 130
 131     switch( header ) {
 132         case SRP_SRP_COMMAND:
 133             dissect_srp_command(tvb,pinfo,srp_tree);
 134             break;
 135
 136         case SRP_SRP_RESPONSE:
 137             break;
 138
 139         case SRP_NSRP_RESPONSE:
 140             if( srp_tree )
 141                 proto_tree_add_item(srp_tree,hf_srp_seqno,tvb,1,1,ENC_BIG_ENDIAN);
 142             break;
 143
 144         default:
 145             break;
 146     }
 147
 148     if( srp_tree ) {
 149         guint16 crc, calc_crc;
 150         guint crc_offset = tvb_reported_length(tvb)-2;
 151         crc = tvb_get_letohs(tvb,-2);
 152
 153         /* crc includes the header */
 154         calc_crc = crc16_ccitt_tvb(tvb,crc_offset);
 155
 156         if( crc == calc_crc ) {
 157             proto_tree_add_uint_format_value(srp_tree, hf_srp_crc, tvb,
 158                                        crc_offset, 2, crc,
 159                                        "0x%04x (correct)", crc);
 160         } else {
 161             hidden_item = proto_tree_add_boolean(srp_tree, hf_srp_crc_bad, tvb,
 162                                           crc_offset, 2, TRUE);
 163             PROTO_ITEM_SET_HIDDEN(hidden_item);
 164             proto_tree_add_uint_format_value(srp_tree, hf_srp_crc, tvb,
 165                                        crc_offset, 2, crc,
 166                                        "0x%04x (incorrect, should be 0x%04x)",
 167                                        crc,
 168                                        calc_crc);
 169         }
 170     }
 171
 172 }
 173
 174 void proto_register_ccsrl (void)
 175 {
 176     static hf_register_info hf[] = {
 177         { &hf_ccsrl_ls,
 178           { "Last Segment","ccsrl.ls",FT_UINT8, BASE_HEX, ccsrl_ls_vals, 0x0,
 179             "Last segment indicator", HFILL}},
 180     };
 181
 182     static gint *ett[] = {
 183         &ett_ccsrl,
 184     };
 185
 186     proto_ccsrl = proto_register_protocol ("H.324/CCSRL", "CCSRL", "ccsrl");
 187     proto_register_field_array (proto_ccsrl, hf, array_length (hf));
 188     proto_register_subtree_array (ett, array_length (ett));
 189     register_dissector("ccsrl", dissect_ccsrl, proto_ccsrl);
 190 }
 191
 192 void proto_register_srp (void)
 193 {
 194     static hf_register_info hf[] = {
 195         {&hf_srp_header,
 196          { "Header", "srp.header", FT_UINT8, BASE_DEC, srp_frame_types, 0x0,
 197            "SRP header octet", HFILL }},
 198         {&hf_srp_seqno,
 199          { "Sequence Number", "srp.seqno", FT_UINT8, BASE_DEC, NULL, 0x0,
 200            NULL, HFILL }},
 201         {&hf_srp_crc,
 202          { "CRC", "srp.crc", FT_UINT16, BASE_HEX, NULL, 0x0,
 203            NULL, HFILL }},
 204         { &hf_srp_crc_bad,
 205           { "Bad CRC","srp.crc_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
 206             NULL, HFILL }},
 207     };
 208
 209     static gint *ett[] = {
 210         &ett_srp,
 211     };
 212
 213     proto_srp = proto_register_protocol ("H.324/SRP", "SRP", "srp");
 214     proto_register_field_array (proto_srp, hf, array_length (hf));
 215     proto_register_subtree_array (ett, array_length (ett));
 216     register_dissector("srp", dissect_srp, proto_srp);
 217
 218     /* register our init routine to be called at the start of a capture,
 219        to clear out our hash tables etc */
 220     /* register_init_routine(&srp_init_protocol); */
 221
 222 }
 223
 224
 225 void proto_reg_handoff_srp(void) {
 226     ccsrl_handle = find_dissector("ccsrl");
 227     h245dg_handle = find_dissector("h245dg");
 228 }