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 1.19 2001/06/18 02:17:53 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@zing.org>
   9  * Copyright 1998
  10  *
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  25  */
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #ifdef HAVE_SYS_TYPES_H
  32 # include <sys/types.h>
  33 #endif
  34
  35 #include <stdio.h>
  36 #include <glib.h>
  37 #include <string.h>
  38 #include "packet.h"
  39 #include "xdlc.h"
  40
  41 #define FROM_DCE        0x80
  42
  43 static int proto_v120 = -1;
  44 static int hf_v120_address = -1;
  45 static int hf_v120_control = -1;
  46 static int hf_v120_header = -1;
  47
  48 static gint ett_v120 = -1;
  49 static gint ett_v120_address = -1;
  50 static gint ett_v120_control = -1;
  51 static gint ett_v120_header = -1;
  52
  53 static int dissect_v120_header(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree);
  54
  55 static void
  56 dissect_v120(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  57 {
  58     proto_tree  *v120_tree, *tc, *address_tree;
  59     proto_item  *ti;
  60     int         is_response;
  61     int         addr;
  62     char        info[80];
  63     int         v120len;
  64     guint8      byte0, byte1;
  65     guint16     control;
  66     tvbuff_t    *next_tvb;
  67
  68     if (check_col(pinfo->fd, COL_PROTOCOL))
  69         col_set_str(pinfo->fd, COL_PROTOCOL, "V.120");
  70     if (check_col(pinfo->fd, COL_INFO))
  71         col_clear(pinfo->fd, COL_INFO);
  72
  73     byte0 = tvb_get_guint8(tvb, 0);
  74
  75     if(check_col(pinfo->fd, COL_RES_DL_SRC))
  76         col_add_fstr(pinfo->fd, COL_RES_DL_SRC, "0x%02X", byte0);
  77
  78     byte1 = tvb_get_guint8(tvb, 1);
  79
  80     if ((byte0 & 0x01) != 0x00 && (byte1 && 0x01) != 0x01)
  81     {
  82         if (check_col(pinfo->fd, COL_INFO))
  83             col_set_str(pinfo->fd, COL_INFO, "Invalid V.120 frame");
  84         if (tree)
  85             ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, tvb_length(tvb),
  86                                             "Invalid V.120 frame");
  87         return;
  88     }
  89
  90     if (pinfo->pseudo_header->x25.flags & FROM_DCE) {
  91         if(check_col(pinfo->fd, COL_RES_DL_DST))
  92             col_set_str(pinfo->fd, COL_RES_DL_DST, "DTE");
  93         if(check_col(pinfo->fd, COL_RES_DL_SRC))
  94             col_set_str(pinfo->fd, COL_RES_DL_SRC, "DCE");
  95     }
  96     else {
  97         if(check_col(pinfo->fd, COL_RES_DL_DST))
  98             col_set_str(pinfo->fd, COL_RES_DL_DST, "DCE");
  99         if(check_col(pinfo->fd, COL_RES_DL_SRC))
 100             col_set_str(pinfo->fd, COL_RES_DL_SRC, "DTE");
 101     }
 102
 103     if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 & 0x02) ||
 104        (!(pinfo->pseudo_header->x25.flags & FROM_DCE) && !(byte0 & 0x02)))
 105         is_response = TRUE;
 106     else
 107         is_response = FALSE;
 108
 109     if (tree) {
 110         ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, 0, "V.120");
 111         v120_tree = proto_item_add_subtree(ti, ett_v120);
 112         addr = byte1 << 8 | byte0;
 113         sprintf(info, "LLI: %d C/R: %s",
 114                         ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1),
 115                         byte0 & 0x02 ? "R" : "C");
 116         tc = proto_tree_add_text(v120_tree, tvb,
 117                         0, 2,
 118                         "Address field: %s", info);
 119         address_tree = proto_item_add_subtree(tc, ett_v120_address);
 120         proto_tree_add_text(address_tree, tvb, 0, 2,
 121                     decode_boolean_bitfield(addr, 0x0002, 2*8,
 122                         "Response", "Command"), NULL);
 123         sprintf(info, "LLI: %d", ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1));
 124         proto_tree_add_text(address_tree, tvb, 0, 2,
 125                     decode_numeric_bitfield(addr, 0xfefc, 2*8, info));
 126         proto_tree_add_text(address_tree, tvb, 0, 2,
 127                     decode_boolean_bitfield(addr, 0x0001, 2*8,
 128                         "EA0 = 1 (Error)", "EA0 = 0"), NULL);
 129         proto_tree_add_text(address_tree, tvb, 0, 2,
 130                     decode_boolean_bitfield(addr, 0x0100, 2*8,
 131                         "EA1 = 1", "EA1 = 0 (Error)"), NULL);
 132     }
 133     else {
 134         v120_tree = NULL;
 135         ti = NULL;
 136     }
 137     control = dissect_xdlc_control(tvb, 2, pinfo, v120_tree, hf_v120_control,
 138             ett_v120_control, is_response, TRUE);
 139     if (tree) {
 140         v120len = 2 + XDLC_CONTROL_LEN(control, TRUE);
 141         if (tvb_bytes_exist(tvb, v120len, 1))
 142                 v120len += dissect_v120_header(tvb, v120len, pinfo, v120_tree);
 143         proto_item_set_len(ti, v120len);
 144         next_tvb = tvb_new_subset(tvb, v120len, -1, -1);
 145         dissect_data(next_tvb, 0, pinfo, v120_tree);
 146     }
 147 }
 148
 149 static int
 150 dissect_v120_header(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree)
 151 {
 152         char info[80];
 153         int header_len, nbits;
 154         int header;
 155         proto_tree *h_tree, *tc;
 156         guint8  byte0;
 157
 158         byte0 = tvb_get_guint8(tvb, offset);
 159
 160         if (byte0 & 0x80) {
 161                 header_len = 1;
 162                 header = byte0;
 163         } else {
 164                 header_len = 2;
 165                 header = byte0 | tvb_get_guint8(tvb, offset + 1) << 8;
 166         }
 167         nbits = header_len * 8;
 168         sprintf(info, "Header: B: %d F: %d", byte0 & 0x02 ? 1:0,
 169                         byte0 & 0x01 ? 1:0);
 170         tc = proto_tree_add_text(tree, tvb,
 171                         offset, header_len,
 172                         "Header octet: %s (0x%02X)", info, byte0);
 173         h_tree = proto_item_add_subtree(tc, ett_v120_header);
 174         proto_tree_add_text(h_tree, tvb, offset, header_len,
 175                     decode_boolean_bitfield(header, 0x80, nbits,
 176                         "No extension octet", "Extension octet follows"), NULL);
 177         proto_tree_add_text(h_tree, tvb, offset, header_len,
 178                     decode_boolean_bitfield(header, 0x40, nbits,
 179                         "Break condition", "No break condition"), NULL);
 180         sprintf(info, "Error control C1/C2: %d", (header & 0x0c) >> 2);
 181         proto_tree_add_text(h_tree, tvb, offset, header_len,
 182                     decode_numeric_bitfield(header, 0x0c, nbits, info));
 183         proto_tree_add_text(h_tree, tvb, offset, header_len,
 184                     decode_boolean_bitfield(header, 0x02, nbits,
 185                         "Segmentation bit B", "No segmentation bit B"), NULL);
 186         proto_tree_add_text(h_tree, tvb, offset, header_len,
 187                     decode_boolean_bitfield(header, 0x01, nbits,
 188                         "Segmentation bit F", "No segmentation bit F"), NULL);
 189         if (header_len == 2) {
 190                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 191                     decode_boolean_bitfield(header, 0x8000, nbits,
 192                         "E", "E bit not set (Error)"), NULL);
 193                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 194                     decode_boolean_bitfield(header, 0x4000, nbits,
 195                         "DR", "No DR"), NULL);
 196                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 197                     decode_boolean_bitfield(header, 0x2000, nbits,
 198                         "SR", "No SR"), NULL);
 199                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 200                     decode_boolean_bitfield(header, 0x1000, nbits,
 201                         "RR", "No RR"), NULL);
 202         }
 203         return header_len;
 204 }
 205
 206 void
 207 proto_register_v120(void)
 208 {
 209     static hf_register_info hf[] = {
 210         { &hf_v120_address,
 211           { "Link Address", "v120.address", FT_UINT16, BASE_HEX, NULL,
 212                   0x0, "", HFILL }},
 213         { &hf_v120_control,
 214           { "Control Field", "v120.control", FT_UINT16, BASE_HEX, NULL, 0x0,
 215                 "", HFILL }},
 216         { &hf_v120_header,
 217           { "Header Field", "v120.header", FT_STRING, BASE_NONE, NULL, 0x0,
 218                 "", HFILL }},
 219     };
 220     static gint *ett[] = {
 221         &ett_v120,
 222         &ett_v120_address,
 223         &ett_v120_control,
 224         &ett_v120_header,
 225     };
 226
 227     proto_v120 = proto_register_protocol("Async data over ISDN (V.120)",
 228                                          "V.120", "v120");
 229     proto_register_field_array (proto_v120, hf, array_length(hf));
 230     proto_register_subtree_array(ett, array_length(ett));
 231 }
 232
 233 void
 234 proto_reg_handoff_v120(void)
 235 {
 236         dissector_add("wtap_encap", WTAP_ENCAP_V120, dissect_v120,
 237             proto_v120);
 238 }