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 1.9 2000/05/31 03:58:54 gram 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 "packet-v120.h"
  40 #include "xdlc.h"
  41
  42 #define FROM_DCE        0x80
  43
  44 static int proto_v120 = -1;
  45 static int hf_v120_address = -1;
  46 static int hf_v120_control = -1;
  47 static int hf_v120_header = -1;
  48
  49 static gint ett_v120 = -1;
  50 static gint ett_v120_address = -1;
  51 static gint ett_v120_control = -1;
  52 static gint ett_v120_header = -1;
  53
  54 static int dissect_v120_header(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree);
  55
  56 void
  57 dissect_v120(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  58 {
  59     proto_tree  *v120_tree, *tc, *address_tree;
  60     proto_item  *ti;
  61     int         is_response;
  62     int         addr;
  63     char        info[80];
  64     int         v120len;
  65     guint8      byte0, byte1;
  66     guint16     control;
  67     tvbuff_t    *next_tvb;
  68
  69     pinfo->current_proto = "V.120";
  70
  71     if (check_col(pinfo->fd, COL_PROTOCOL))
  72         col_add_str(pinfo->fd, COL_PROTOCOL, "V.120");
  73
  74     byte0 = tvb_get_guint8(tvb, 0);
  75
  76     if(check_col(pinfo->fd, COL_RES_DL_SRC))
  77         col_add_fstr(pinfo->fd, COL_RES_DL_SRC, "0x%02X", byte0);
  78
  79     byte1 = tvb_get_guint8(tvb, 1);
  80
  81     if ((byte0 & 0x01) != 0x00 && (byte1 && 0x01) != 0x01)
  82     {
  83         if (check_col(pinfo->fd, COL_INFO))
  84             col_add_str(pinfo->fd, COL_INFO, "Invalid V.120 frame");
  85         if (tree)
  86             ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, pinfo->fd->cap_len,
  87                                             "Invalid V.120 frame");
  88         return;
  89     }
  90
  91     if (pinfo->pseudo_header->x25.flags & FROM_DCE) {
  92         if(check_col(pinfo->fd, COL_RES_DL_DST))
  93             col_add_str(pinfo->fd, COL_RES_DL_DST, "DTE");
  94         if(check_col(pinfo->fd, COL_RES_DL_SRC))
  95             col_add_str(pinfo->fd, COL_RES_DL_SRC, "DCE");
  96     }
  97     else {
  98         if(check_col(pinfo->fd, COL_RES_DL_DST))
  99             col_add_str(pinfo->fd, COL_RES_DL_DST, "DCE");
 100         if(check_col(pinfo->fd, COL_RES_DL_SRC))
 101             col_add_str(pinfo->fd, COL_RES_DL_SRC, "DTE");
 102     }
 103
 104     if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 & 0x02) ||
 105        (!(pinfo->pseudo_header->x25.flags & FROM_DCE) && !(byte0 & 0x02)))
 106         is_response = TRUE;
 107     else
 108         is_response = FALSE;
 109
 110     if (tree) {
 111         ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, 0, "V.120");
 112         v120_tree = proto_item_add_subtree(ti, ett_v120);
 113         addr = byte1 << 8 | byte0;
 114         sprintf(info, "LLI: %d C/R: %s",
 115                         ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1),
 116                         byte0 & 0x02 ? "R" : "C");
 117         tc = proto_tree_add_text(v120_tree, tvb,
 118                         0, 2,
 119                         "Address field: %s", info);
 120         address_tree = proto_item_add_subtree(tc, ett_v120_address);
 121         proto_tree_add_text(address_tree, tvb, 0, 2,
 122                     decode_boolean_bitfield(addr, 0x0002, 2*8,
 123                         "Response", "Command"), NULL);
 124         sprintf(info, "LLI: %d", ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1));
 125         proto_tree_add_text(address_tree, tvb, 0, 2,
 126                     decode_numeric_bitfield(addr, 0xfefc, 2*8, info));
 127         proto_tree_add_text(address_tree, tvb, 0, 2,
 128                     decode_boolean_bitfield(addr, 0x0001, 2*8,
 129                         "EA0 = 1 (Error)", "EA0 = 0"), NULL);
 130         proto_tree_add_text(address_tree, tvb, 0, 2,
 131                     decode_boolean_bitfield(addr, 0x0100, 2*8,
 132                         "EA1 = 1", "EA1 = 0 (Error)"), NULL);
 133     }
 134     else {
 135         v120_tree = NULL;
 136         ti = NULL;
 137     }
 138     control = dissect_xdlc_control(tvb, 2, pinfo, v120_tree, hf_v120_control,
 139             ett_v120_control, is_response, TRUE);
 140     if (tree) {
 141         v120len = 2 + XDLC_CONTROL_LEN(control, TRUE);
 142         if (tvb_bytes_exist(tvb, v120len, 1))
 143                 v120len += dissect_v120_header(tvb, v120len, pinfo, v120_tree);
 144         proto_item_set_len(ti, v120len);
 145         next_tvb = tvb_new_subset(tvb, v120len, -1, -1);
 146         dissect_data_tvb(next_tvb, pinfo, v120_tree);
 147     }
 148 }
 149
 150 static int
 151 dissect_v120_header(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree)
 152 {
 153         char info[80];
 154         int header_len, nbits;
 155         int header;
 156         proto_tree *h_tree, *tc;
 157         guint8  byte0;
 158
 159         byte0 = tvb_get_guint8(tvb, offset);
 160
 161         if (byte0 & 0x80) {
 162                 header_len = 1;
 163                 header = byte0;
 164         } else {
 165                 header_len = 2;
 166                 header = byte0 | tvb_get_guint8(tvb, offset + 1) << 8;
 167         }
 168         nbits = header_len * 8;
 169         sprintf(info, "Header: B: %d F: %d", byte0 & 0x02 ? 1:0,
 170                         byte0 & 0x01 ? 1:0);
 171         tc = proto_tree_add_text(tree, tvb,
 172                         offset, header_len,
 173                         "Header octet: %s (0x%02X)", info, byte0);
 174         h_tree = proto_item_add_subtree(tc, ett_v120_header);
 175         proto_tree_add_text(h_tree, tvb, offset, header_len,
 176                     decode_boolean_bitfield(header, 0x80, nbits,
 177                         "No extension octet", "Extension octet follows"), NULL);
 178         proto_tree_add_text(h_tree, tvb, offset, header_len,
 179                     decode_boolean_bitfield(header, 0x40, nbits,
 180                         "Break condition", "No break condition"), NULL);
 181         sprintf(info, "Error control C1/C2: %d", (header & 0x0c) >> 2);
 182         proto_tree_add_text(h_tree, tvb, offset, header_len,
 183                     decode_numeric_bitfield(header, 0x0c, nbits, info));
 184         proto_tree_add_text(h_tree, tvb, offset, header_len,
 185                     decode_boolean_bitfield(header, 0x02, nbits,
 186                         "Segmentation bit B", "No segmentation bit B"), NULL);
 187         proto_tree_add_text(h_tree, tvb, offset, header_len,
 188                     decode_boolean_bitfield(header, 0x01, nbits,
 189                         "Segmentation bit F", "No segmentation bit F"), NULL);
 190         if (header_len == 2) {
 191                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 192                     decode_boolean_bitfield(header, 0x8000, nbits,
 193                         "E", "E bit not set (Error)"), NULL);
 194                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 195                     decode_boolean_bitfield(header, 0x4000, nbits,
 196                         "DR", "No DR"), NULL);
 197                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 198                     decode_boolean_bitfield(header, 0x2000, nbits,
 199                         "SR", "No SR"), NULL);
 200                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 201                     decode_boolean_bitfield(header, 0x1000, nbits,
 202                         "RR", "No RR"), NULL);
 203         }
 204         return header_len;
 205 }
 206
 207 void
 208 proto_register_v120(void)
 209 {
 210     static hf_register_info hf[] = {
 211         { &hf_v120_address,
 212           { "Link Address", "v120.address", FT_UINT16, BASE_HEX, NULL,
 213                   0x0, "" }},
 214         { &hf_v120_control,
 215           { "Control Field", "v120.control", FT_UINT16, BASE_HEX, NULL, 0x0,
 216                 "" }},
 217         { &hf_v120_header,
 218           { "Header Field", "v120.header", FT_STRING, BASE_NONE, NULL, 0x0,
 219                 "" }},
 220     };
 221     static gint *ett[] = {
 222         &ett_v120,
 223         &ett_v120_address,
 224         &ett_v120_control,
 225         &ett_v120_header,
 226     };
 227
 228     proto_v120 = proto_register_protocol ("Async data over ISDN (V.120)", "v120");
 229     proto_register_field_array (proto_v120, hf, array_length(hf));
 230     proto_register_subtree_array(ett, array_length(ett));
 231 }