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 1.26 2002/04/11 09:38:03 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 #ifdef HAVE_SYS_TYPES_H
  31 # include <sys/types.h>
  32 #endif
  33
  34 #include <stdio.h>
  35 #include <glib.h>
  36 #include <string.h>
  37 #include <epan/packet.h>
  38 #include "xdlc.h"
  39
  40 static int proto_v120 = -1;
  41 static int hf_v120_address = -1;
  42 static int hf_v120_control = -1;
  43 static int hf_v120_header = -1;
  44
  45 static gint ett_v120 = -1;
  46 static gint ett_v120_address = -1;
  47 static gint ett_v120_control = -1;
  48 static gint ett_v120_header = -1;
  49
  50 static dissector_handle_t data_handle;
  51
  52 static int dissect_v120_header(tvbuff_t *tvb, int offset, proto_tree *tree);
  53
  54 static void
  55 dissect_v120(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  56 {
  57     proto_tree  *v120_tree, *tc, *address_tree;
  58     proto_item  *ti;
  59     int         is_response;
  60     int         addr;
  61     char        info[80];
  62     int         v120len;
  63     guint8      byte0, byte1;
  64     guint16     control;
  65     tvbuff_t    *next_tvb;
  66
  67     if (check_col(pinfo->cinfo, COL_PROTOCOL))
  68         col_set_str(pinfo->cinfo, COL_PROTOCOL, "V.120");
  69     if (check_col(pinfo->cinfo, COL_INFO))
  70         col_clear(pinfo->cinfo, COL_INFO);
  71
  72     byte0 = tvb_get_guint8(tvb, 0);
  73
  74     if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  75         col_add_fstr(pinfo->cinfo, COL_RES_DL_SRC, "0x%02X", byte0);
  76
  77     byte1 = tvb_get_guint8(tvb, 1);
  78
  79     if ((byte0 & 0x01) != 0x00 && (byte1 && 0x01) != 0x01)
  80     {
  81         if (check_col(pinfo->cinfo, COL_INFO))
  82             col_set_str(pinfo->cinfo, COL_INFO, "Invalid V.120 frame");
  83         if (tree)
  84             ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, -1,
  85                                             "Invalid V.120 frame");
  86         return;
  87     }
  88
  89     if (pinfo->pseudo_header->x25.flags & FROM_DCE) {
  90         if(check_col(pinfo->cinfo, COL_RES_DL_DST))
  91             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
  92         if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  93             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
  94     }
  95     else {
  96         if(check_col(pinfo->cinfo, COL_RES_DL_DST))
  97             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
  98         if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  99             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
 100     }
 101
 102     if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 & 0x02) ||
 103        (!(pinfo->pseudo_header->x25.flags & FROM_DCE) && !(byte0 & 0x02)))
 104         is_response = TRUE;
 105     else
 106         is_response = FALSE;
 107
 108     if (tree) {
 109         ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, -1, "V.120");
 110         v120_tree = proto_item_add_subtree(ti, ett_v120);
 111         addr = byte1 << 8 | byte0;
 112         sprintf(info, "LLI: %d C/R: %s",
 113                         ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1),
 114                         byte0 & 0x02 ? "R" : "C");
 115         tc = proto_tree_add_text(v120_tree, tvb,
 116                         0, 2,
 117                         "Address field: %s", info);
 118         address_tree = proto_item_add_subtree(tc, ett_v120_address);
 119         proto_tree_add_text(address_tree, tvb, 0, 2,
 120                     decode_boolean_bitfield(addr, 0x0002, 2*8,
 121                         "Response", "Command"), NULL);
 122         sprintf(info, "LLI: %d", ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1));
 123         proto_tree_add_text(address_tree, tvb, 0, 2,
 124                     decode_numeric_bitfield(addr, 0xfefc, 2*8, info));
 125         proto_tree_add_text(address_tree, tvb, 0, 2,
 126                     decode_boolean_bitfield(addr, 0x0001, 2*8,
 127                         "EA0 = 1 (Error)", "EA0 = 0"), NULL);
 128         proto_tree_add_text(address_tree, tvb, 0, 2,
 129                     decode_boolean_bitfield(addr, 0x0100, 2*8,
 130                         "EA1 = 1", "EA1 = 0 (Error)"), NULL);
 131     }
 132     else {
 133         v120_tree = NULL;
 134         ti = NULL;
 135     }
 136     control = dissect_xdlc_control(tvb, 2, pinfo, v120_tree, hf_v120_control,
 137             ett_v120_control, is_response, TRUE);
 138     if (tree) {
 139         v120len = 2 + XDLC_CONTROL_LEN(control, TRUE);
 140         if (tvb_bytes_exist(tvb, v120len, 1))
 141                 v120len += dissect_v120_header(tvb, v120len, v120_tree);
 142         proto_item_set_len(ti, v120len);
 143         next_tvb = tvb_new_subset(tvb, v120len, -1, -1);
 144         call_dissector(data_handle,next_tvb, pinfo, v120_tree);
 145     }
 146 }
 147
 148 static int
 149 dissect_v120_header(tvbuff_t *tvb, int offset, proto_tree *tree)
 150 {
 151         char info[80];
 152         int header_len, nbits;
 153         int header;
 154         proto_tree *h_tree, *tc;
 155         guint8  byte0;
 156
 157         byte0 = tvb_get_guint8(tvb, offset);
 158
 159         if (byte0 & 0x80) {
 160                 header_len = 1;
 161                 header = byte0;
 162         } else {
 163                 header_len = 2;
 164                 header = byte0 | tvb_get_guint8(tvb, offset + 1) << 8;
 165         }
 166         nbits = header_len * 8;
 167         sprintf(info, "Header: B: %d F: %d", byte0 & 0x02 ? 1:0,
 168                         byte0 & 0x01 ? 1:0);
 169         tc = proto_tree_add_text(tree, tvb,
 170                         offset, header_len,
 171                         "Header octet: %s (0x%02X)", info, byte0);
 172         h_tree = proto_item_add_subtree(tc, ett_v120_header);
 173         proto_tree_add_text(h_tree, tvb, offset, header_len,
 174                     decode_boolean_bitfield(header, 0x80, nbits,
 175                         "No extension octet", "Extension octet follows"), NULL);
 176         proto_tree_add_text(h_tree, tvb, offset, header_len,
 177                     decode_boolean_bitfield(header, 0x40, nbits,
 178                         "Break condition", "No break condition"), NULL);
 179         sprintf(info, "Error control C1/C2: %d", (header & 0x0c) >> 2);
 180         proto_tree_add_text(h_tree, tvb, offset, header_len,
 181                     decode_numeric_bitfield(header, 0x0c, nbits, info));
 182         proto_tree_add_text(h_tree, tvb, offset, header_len,
 183                     decode_boolean_bitfield(header, 0x02, nbits,
 184                         "Segmentation bit B", "No segmentation bit B"), NULL);
 185         proto_tree_add_text(h_tree, tvb, offset, header_len,
 186                     decode_boolean_bitfield(header, 0x01, nbits,
 187                         "Segmentation bit F", "No segmentation bit F"), NULL);
 188         if (header_len == 2) {
 189                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 190                     decode_boolean_bitfield(header, 0x8000, nbits,
 191                         "E", "E bit not set (Error)"), NULL);
 192                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 193                     decode_boolean_bitfield(header, 0x4000, nbits,
 194                         "DR", "No DR"), NULL);
 195                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 196                     decode_boolean_bitfield(header, 0x2000, nbits,
 197                         "SR", "No SR"), NULL);
 198                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 199                     decode_boolean_bitfield(header, 0x1000, nbits,
 200                         "RR", "No RR"), NULL);
 201         }
 202         return header_len;
 203 }
 204
 205 void
 206 proto_register_v120(void)
 207 {
 208     static hf_register_info hf[] = {
 209         { &hf_v120_address,
 210           { "Link Address", "v120.address", FT_UINT16, BASE_HEX, NULL,
 211                   0x0, "", HFILL }},
 212         { &hf_v120_control,
 213           { "Control Field", "v120.control", FT_UINT16, BASE_HEX, NULL, 0x0,
 214                 "", HFILL }},
 215         { &hf_v120_header,
 216           { "Header Field", "v120.header", FT_STRING, BASE_NONE, NULL, 0x0,
 217                 "", HFILL }},
 218     };
 219     static gint *ett[] = {
 220         &ett_v120,
 221         &ett_v120_address,
 222         &ett_v120_control,
 223         &ett_v120_header,
 224     };
 225
 226     proto_v120 = proto_register_protocol("Async data over ISDN (V.120)",
 227                                          "V.120", "v120");
 228     proto_register_field_array (proto_v120, hf, array_length(hf));
 229     proto_register_subtree_array(ett, array_length(ett));
 230 }
 231
 232 void
 233 proto_reg_handoff_v120(void)
 234 {
 235     dissector_handle_t v120_handle;
 236
 237     data_handle = find_dissector("data");
 238     v120_handle = create_dissector_handle(dissect_v120, proto_v120);
 239     dissector_add("wtap_encap", WTAP_ENCAP_V120, v120_handle);
 240 }