packet-v120.c

   1 /* packet-v120.c
   2  * Routines for v120 frame disassembly
   3  * Bert Driehuis <driehuis@playbeing.org>
   4  *
   5  * $Id: packet-v120.c,v 1.30 2002/10/31 07:43:10 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@ethereal.com>
   9  * Copyright 1998
  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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  24  */
  25
  26 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <stdio.h>
  31 #include <glib.h>
  32 #include <string.h>
  33 #include <epan/packet.h>
  34 #include "xdlc.h"
  35
  36 static int proto_v120 = -1;
  37 static int hf_v120_address = -1;
  38 static int hf_v120_control = -1;
  39 static int hf_v120_header = -1;
  40
  41 static gint ett_v120 = -1;
  42 static gint ett_v120_address = -1;
  43 static gint ett_v120_control = -1;
  44 static gint ett_v120_header = -1;
  45
  46 static dissector_handle_t data_handle;
  47
  48 static int dissect_v120_header(tvbuff_t *tvb, int offset, proto_tree *tree);
  49
  50 static void
  51 dissect_v120(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  52 {
  53     proto_tree  *v120_tree, *tc, *address_tree;
  54     proto_item  *ti;
  55     int         is_response;
  56     int         addr;
  57     char        info[80];
  58     int         v120len;
  59     guint8      byte0, byte1;
  60     guint16     control;
  61     tvbuff_t    *next_tvb;
  62
  63     if (check_col(pinfo->cinfo, COL_PROTOCOL))
  64         col_set_str(pinfo->cinfo, COL_PROTOCOL, "V.120");
  65     if (check_col(pinfo->cinfo, COL_INFO))
  66         col_clear(pinfo->cinfo, COL_INFO);
  67
  68     byte0 = tvb_get_guint8(tvb, 0);
  69
  70     if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  71         col_add_fstr(pinfo->cinfo, COL_RES_DL_SRC, "0x%02X", byte0);
  72
  73     byte1 = tvb_get_guint8(tvb, 1);
  74
  75     if ((byte0 & 0x01) != 0x00 && (byte1 && 0x01) != 0x01)
  76     {
  77         if (check_col(pinfo->cinfo, COL_INFO))
  78             col_set_str(pinfo->cinfo, COL_INFO, "Invalid V.120 frame");
  79         if (tree)
  80             ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, -1,
  81                                             "Invalid V.120 frame");
  82         return;
  83     }
  84
  85     if (pinfo->p2p_dir == P2P_DIR_SENT) {
  86         is_response = (byte0 & 0x02) ? FALSE: TRUE;
  87         if(check_col(pinfo->cinfo, COL_RES_DL_DST))
  88             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
  89         if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  90             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
  91     } else {
  92         /* XXX - what if the direction is unknown? */
  93         is_response = (byte0 & 0x02) ? TRUE : FALSE;
  94         if(check_col(pinfo->cinfo, COL_RES_DL_DST))
  95             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
  96         if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  97             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
  98     }
  99
 100     if (tree) {
 101         ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, -1, "V.120");
 102         v120_tree = proto_item_add_subtree(ti, ett_v120);
 103         addr = byte1 << 8 | byte0;
 104         sprintf(info, "LLI: %d C/R: %s",
 105                         ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1),
 106                         byte0 & 0x02 ? "R" : "C");
 107         tc = proto_tree_add_text(v120_tree, tvb,
 108                         0, 2,
 109                         "Address field: %s", info);
 110         address_tree = proto_item_add_subtree(tc, ett_v120_address);
 111         proto_tree_add_text(address_tree, tvb, 0, 2,
 112                     decode_boolean_bitfield(addr, 0x0002, 2*8,
 113                         "Response", "Command"), NULL);
 114         sprintf(info, "LLI: %d", ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1));
 115         proto_tree_add_text(address_tree, tvb, 0, 2,
 116                     decode_numeric_bitfield(addr, 0xfefc, 2*8, info));
 117         proto_tree_add_text(address_tree, tvb, 0, 2,
 118                     decode_boolean_bitfield(addr, 0x0001, 2*8,
 119                         "EA0 = 1 (Error)", "EA0 = 0"), NULL);
 120         proto_tree_add_text(address_tree, tvb, 0, 2,
 121                     decode_boolean_bitfield(addr, 0x0100, 2*8,
 122                         "EA1 = 1", "EA1 = 0 (Error)"), NULL);
 123     }
 124     else {
 125         v120_tree = NULL;
 126         ti = NULL;
 127     }
 128     control = dissect_xdlc_control(tvb, 2, pinfo, v120_tree, hf_v120_control,
 129             ett_v120_control, is_response, TRUE);
 130     if (tree) {
 131         v120len = 2 + XDLC_CONTROL_LEN(control, TRUE);
 132         if (tvb_bytes_exist(tvb, v120len, 1))
 133                 v120len += dissect_v120_header(tvb, v120len, v120_tree);
 134         proto_item_set_len(ti, v120len);
 135         next_tvb = tvb_new_subset(tvb, v120len, -1, -1);
 136         call_dissector(data_handle,next_tvb, pinfo, v120_tree);
 137     }
 138 }
 139
 140 static int
 141 dissect_v120_header(tvbuff_t *tvb, int offset, proto_tree *tree)
 142 {
 143         char info[80];
 144         int header_len, nbits;
 145         int header;
 146         proto_tree *h_tree, *tc;
 147         guint8  byte0;
 148
 149         byte0 = tvb_get_guint8(tvb, offset);
 150
 151         if (byte0 & 0x80) {
 152                 header_len = 1;
 153                 header = byte0;
 154         } else {
 155                 header_len = 2;
 156                 header = byte0 | tvb_get_guint8(tvb, offset + 1) << 8;
 157         }
 158         nbits = header_len * 8;
 159         sprintf(info, "Header: B: %d F: %d", byte0 & 0x02 ? 1:0,
 160                         byte0 & 0x01 ? 1:0);
 161         tc = proto_tree_add_text(tree, tvb,
 162                         offset, header_len,
 163                         "Header octet: %s (0x%02X)", info, byte0);
 164         h_tree = proto_item_add_subtree(tc, ett_v120_header);
 165         proto_tree_add_text(h_tree, tvb, offset, header_len,
 166                     decode_boolean_bitfield(header, 0x80, nbits,
 167                         "No extension octet", "Extension octet follows"), NULL);
 168         proto_tree_add_text(h_tree, tvb, offset, header_len,
 169                     decode_boolean_bitfield(header, 0x40, nbits,
 170                         "Break condition", "No break condition"), NULL);
 171         sprintf(info, "Error control C1/C2: %d", (header & 0x0c) >> 2);
 172         proto_tree_add_text(h_tree, tvb, offset, header_len,
 173                     decode_numeric_bitfield(header, 0x0c, nbits, info));
 174         proto_tree_add_text(h_tree, tvb, offset, header_len,
 175                     decode_boolean_bitfield(header, 0x02, nbits,
 176                         "Segmentation bit B", "No segmentation bit B"), NULL);
 177         proto_tree_add_text(h_tree, tvb, offset, header_len,
 178                     decode_boolean_bitfield(header, 0x01, nbits,
 179                         "Segmentation bit F", "No segmentation bit F"), NULL);
 180         if (header_len == 2) {
 181                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 182                     decode_boolean_bitfield(header, 0x8000, nbits,
 183                         "E", "E bit not set (Error)"), NULL);
 184                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 185                     decode_boolean_bitfield(header, 0x4000, nbits,
 186                         "DR", "No DR"), NULL);
 187                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 188                     decode_boolean_bitfield(header, 0x2000, nbits,
 189                         "SR", "No SR"), NULL);
 190                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 191                     decode_boolean_bitfield(header, 0x1000, nbits,
 192                         "RR", "No RR"), NULL);
 193         }
 194         return header_len;
 195 }
 196
 197 void
 198 proto_register_v120(void)
 199 {
 200     static hf_register_info hf[] = {
 201         { &hf_v120_address,
 202           { "Link Address", "v120.address", FT_UINT16, BASE_HEX, NULL,
 203                   0x0, "", HFILL }},
 204         { &hf_v120_control,
 205           { "Control Field", "v120.control", FT_UINT16, BASE_HEX, NULL, 0x0,
 206                 "", HFILL }},
 207         { &hf_v120_header,
 208           { "Header Field", "v120.header", FT_STRING, BASE_NONE, NULL, 0x0,
 209                 "", HFILL }},
 210     };
 211     static gint *ett[] = {
 212         &ett_v120,
 213         &ett_v120_address,
 214         &ett_v120_control,
 215         &ett_v120_header,
 216     };
 217
 218     proto_v120 = proto_register_protocol("Async data over ISDN (V.120)",
 219                                          "V.120", "v120");
 220     proto_register_field_array (proto_v120, hf, array_length(hf));
 221     proto_register_subtree_array(ett, array_length(ett));
 222
 223     register_dissector("v120", dissect_v120, proto_v120);
 224 }
 225
 226 void
 227 proto_reg_handoff_v120(void)
 228 {
 229     data_handle = find_dissector("data");
 230 }