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 1.28 2002/08/28 21:00:36 jmayer 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->pseudo_header->x25.flags & FROM_DCE) {
  86         if(check_col(pinfo->cinfo, COL_RES_DL_DST))
  87             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DTE");
  88         if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  89             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DCE");
  90     }
  91     else {
  92         if(check_col(pinfo->cinfo, COL_RES_DL_DST))
  93             col_set_str(pinfo->cinfo, COL_RES_DL_DST, "DCE");
  94         if(check_col(pinfo->cinfo, COL_RES_DL_SRC))
  95             col_set_str(pinfo->cinfo, COL_RES_DL_SRC, "DTE");
  96     }
  97
  98     if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 & 0x02) ||
  99        (!(pinfo->pseudo_header->x25.flags & FROM_DCE) && !(byte0 & 0x02)))
 100         is_response = TRUE;
 101     else
 102         is_response = FALSE;
 103
 104     if (tree) {
 105         ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, -1, "V.120");
 106         v120_tree = proto_item_add_subtree(ti, ett_v120);
 107         addr = byte1 << 8 | byte0;
 108         sprintf(info, "LLI: %d C/R: %s",
 109                         ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1),
 110                         byte0 & 0x02 ? "R" : "C");
 111         tc = proto_tree_add_text(v120_tree, tvb,
 112                         0, 2,
 113                         "Address field: %s", info);
 114         address_tree = proto_item_add_subtree(tc, ett_v120_address);
 115         proto_tree_add_text(address_tree, tvb, 0, 2,
 116                     decode_boolean_bitfield(addr, 0x0002, 2*8,
 117                         "Response", "Command"), NULL);
 118         sprintf(info, "LLI: %d", ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1));
 119         proto_tree_add_text(address_tree, tvb, 0, 2,
 120                     decode_numeric_bitfield(addr, 0xfefc, 2*8, info));
 121         proto_tree_add_text(address_tree, tvb, 0, 2,
 122                     decode_boolean_bitfield(addr, 0x0001, 2*8,
 123                         "EA0 = 1 (Error)", "EA0 = 0"), NULL);
 124         proto_tree_add_text(address_tree, tvb, 0, 2,
 125                     decode_boolean_bitfield(addr, 0x0100, 2*8,
 126                         "EA1 = 1", "EA1 = 0 (Error)"), NULL);
 127     }
 128     else {
 129         v120_tree = NULL;
 130         ti = NULL;
 131     }
 132     control = dissect_xdlc_control(tvb, 2, pinfo, v120_tree, hf_v120_control,
 133             ett_v120_control, is_response, TRUE);
 134     if (tree) {
 135         v120len = 2 + XDLC_CONTROL_LEN(control, TRUE);
 136         if (tvb_bytes_exist(tvb, v120len, 1))
 137                 v120len += dissect_v120_header(tvb, v120len, v120_tree);
 138         proto_item_set_len(ti, v120len);
 139         next_tvb = tvb_new_subset(tvb, v120len, -1, -1);
 140         call_dissector(data_handle,next_tvb, pinfo, v120_tree);
 141     }
 142 }
 143
 144 static int
 145 dissect_v120_header(tvbuff_t *tvb, int offset, proto_tree *tree)
 146 {
 147         char info[80];
 148         int header_len, nbits;
 149         int header;
 150         proto_tree *h_tree, *tc;
 151         guint8  byte0;
 152
 153         byte0 = tvb_get_guint8(tvb, offset);
 154
 155         if (byte0 & 0x80) {
 156                 header_len = 1;
 157                 header = byte0;
 158         } else {
 159                 header_len = 2;
 160                 header = byte0 | tvb_get_guint8(tvb, offset + 1) << 8;
 161         }
 162         nbits = header_len * 8;
 163         sprintf(info, "Header: B: %d F: %d", byte0 & 0x02 ? 1:0,
 164                         byte0 & 0x01 ? 1:0);
 165         tc = proto_tree_add_text(tree, tvb,
 166                         offset, header_len,
 167                         "Header octet: %s (0x%02X)", info, byte0);
 168         h_tree = proto_item_add_subtree(tc, ett_v120_header);
 169         proto_tree_add_text(h_tree, tvb, offset, header_len,
 170                     decode_boolean_bitfield(header, 0x80, nbits,
 171                         "No extension octet", "Extension octet follows"), NULL);
 172         proto_tree_add_text(h_tree, tvb, offset, header_len,
 173                     decode_boolean_bitfield(header, 0x40, nbits,
 174                         "Break condition", "No break condition"), NULL);
 175         sprintf(info, "Error control C1/C2: %d", (header & 0x0c) >> 2);
 176         proto_tree_add_text(h_tree, tvb, offset, header_len,
 177                     decode_numeric_bitfield(header, 0x0c, nbits, info));
 178         proto_tree_add_text(h_tree, tvb, offset, header_len,
 179                     decode_boolean_bitfield(header, 0x02, nbits,
 180                         "Segmentation bit B", "No segmentation bit B"), NULL);
 181         proto_tree_add_text(h_tree, tvb, offset, header_len,
 182                     decode_boolean_bitfield(header, 0x01, nbits,
 183                         "Segmentation bit F", "No segmentation bit F"), NULL);
 184         if (header_len == 2) {
 185                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 186                     decode_boolean_bitfield(header, 0x8000, nbits,
 187                         "E", "E bit not set (Error)"), NULL);
 188                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 189                     decode_boolean_bitfield(header, 0x4000, nbits,
 190                         "DR", "No DR"), NULL);
 191                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 192                     decode_boolean_bitfield(header, 0x2000, nbits,
 193                         "SR", "No SR"), NULL);
 194                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 195                     decode_boolean_bitfield(header, 0x1000, nbits,
 196                         "RR", "No RR"), NULL);
 197         }
 198         return header_len;
 199 }
 200
 201 void
 202 proto_register_v120(void)
 203 {
 204     static hf_register_info hf[] = {
 205         { &hf_v120_address,
 206           { "Link Address", "v120.address", FT_UINT16, BASE_HEX, NULL,
 207                   0x0, "", HFILL }},
 208         { &hf_v120_control,
 209           { "Control Field", "v120.control", FT_UINT16, BASE_HEX, NULL, 0x0,
 210                 "", HFILL }},
 211         { &hf_v120_header,
 212           { "Header Field", "v120.header", FT_STRING, BASE_NONE, NULL, 0x0,
 213                 "", HFILL }},
 214     };
 215     static gint *ett[] = {
 216         &ett_v120,
 217         &ett_v120_address,
 218         &ett_v120_control,
 219         &ett_v120_header,
 220     };
 221
 222     proto_v120 = proto_register_protocol("Async data over ISDN (V.120)",
 223                                          "V.120", "v120");
 224     proto_register_field_array (proto_v120, hf, array_length(hf));
 225     proto_register_subtree_array(ett, array_length(ett));
 226 }
 227
 228 void
 229 proto_reg_handoff_v120(void)
 230 {
 231     dissector_handle_t v120_handle;
 232
 233     data_handle = find_dissector("data");
 234     v120_handle = create_dissector_handle(dissect_v120, proto_v120);
 235     dissector_add("wtap_encap", WTAP_ENCAP_V120, v120_handle);
 236 }