epan/dissectors/packet-ax25-nol3.c

   1 /* packet-ax25-nol3.c
   2  *
   3  * Routines for Amateur Packet Radio protocol dissection
   4  * Copyright 2007,2008,2009,2010,2012 R.W. Stearn <richard@rns-stearn.demon.co.uk>
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13 /*
  14  * This dissector is for the "No Layer 3 protocol" PID of the AX.25 Amateur
  15  * Packet-Radio Link-Layer Protocol, Version 2.0, October 1984
  16  *
  17  * At the time of writing the specification could be found here:
  18  *   http://www.tapr.org/pub_ax25.html
  19  *
  20  * Information on the "protocols" recognised by this dissector are drawn from:
  21  *  DX cluster:
  22  *    A network capture kindly donated by Luca Melette.
  23  *  APRS:
  24  *    http://www.aprs.org/
  25  *
  26  * Inspiration on how to build the dissector drawn from
  27  *   packet-sdlc.c
  28  *   packet-x25.c
  29  *   packet-lapb.c
  30  *   paket-gprs-llc.c
  31  *   xdlc.c
  32  * with the base file built from README.developers.
  33  */
  34
  35 #include "config.h"
  36
  37 #include <epan/packet.h>
  38 #include <epan/prefs.h>
  39 #include <epan/ax25_pids.h>
  40
  41 #define STRLEN  80
  42
  43 void proto_register_ax25_nol3(void);
  44 void proto_reg_handoff_ax25_nol3(void);
  45
  46 /* Dissector handles - all the possibles are listed */
  47 static dissector_handle_t aprs_handle;
  48
  49 /* Initialize the protocol and registered fields */
  50 static int proto_ax25_nol3;
  51 static int proto_dx;
  52
  53 static int hf_dx_report;
  54
  55 /* static int hf_text; */
  56
  57 /* Global preferences */
  58 static bool gPREF_APRS;
  59 static bool gPREF_DX;
  60
  61 /* Initialize the subtree pointers */
  62 static int ett_ax25_nol3;
  63
  64 static int ett_dx;
  65
  66
  67 /* Code to actually dissect the packets */
  68 static int
  69 dissect_dx(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_)
  70 {
  71         proto_item *ti;
  72         proto_tree *dx_tree;
  73
  74         int data_len;
  75         int offset;
  76
  77         offset   = 0;
  78         data_len = tvb_reported_length_remaining( tvb, offset );
  79
  80         col_set_str( pinfo->cinfo, COL_PROTOCOL, "DX" );
  81
  82         col_add_str( pinfo->cinfo, COL_INFO, tvb_format_text( pinfo->pool, tvb, offset, 15 ) );
  83
  84         if ( parent_tree )
  85                 {
  86                 /* create display subtree for the protocol */
  87                 ti = proto_tree_add_protocol_format( parent_tree, proto_dx, tvb, 0, -1,
  88                     "DX (%s)", tvb_format_text( pinfo->pool, tvb, offset, 15 ) );
  89                 dx_tree = proto_item_add_subtree( ti, ett_dx );
  90                 offset = 0;
  91
  92                 proto_tree_add_item( dx_tree, hf_dx_report, tvb, offset, data_len, ENC_ASCII );
  93         }
  94
  95         return tvb_captured_length(tvb);
  96 }
  97
  98 static bool
  99 isaprs( uint8_t dti )
 100 {
 101         bool b = false;
 102
 103         switch ( dti )
 104                 {
 105                 case 0x1c       :
 106                 case 0x1d       :
 107                 case '!'        :
 108                 case '#'        :
 109                 case '$'        :
 110                 case '%'        :
 111                 case '&'        :
 112                 case ')'        :
 113                 case '*'        :
 114                 case '+'        :
 115                 case ','        :
 116                 case '.'        :
 117                 case '/'        :
 118                 case ':'        :
 119                 case ';'        :
 120                 case '<'        :
 121                 case '='        :
 122                 case '>'        :
 123                 case '?'        :
 124                 case '@'        :
 125                 case 'T'        :
 126                 case '['        :
 127                 case '\''       :
 128                 case '_'        :
 129                 case '`'        :
 130                 case '{'        :
 131                 case '}'        : b = true; break;
 132                 default         : break;
 133                 }
 134         return b;
 135 }
 136
 137 static int
 138 dissect_ax25_nol3(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_ )
 139 {
 140         proto_item *ti;
 141         proto_tree *ax25_nol3_tree;
 142         char       *info_buffer;
 143         int         offset;
 144         tvbuff_t   *next_tvb = NULL;
 145         uint8_t     dti      = 0;
 146         bool        dissected;
 147
 148         info_buffer = (char *)wmem_alloc( pinfo->pool, STRLEN );
 149         info_buffer[0] = '\0';
 150
 151         col_set_str( pinfo->cinfo, COL_PROTOCOL, "AX.25-NoL3");
 152
 153         col_clear( pinfo->cinfo, COL_INFO);
 154
 155         offset = 0;
 156         snprintf( info_buffer, STRLEN, "Text" );
 157
 158         if ( gPREF_APRS )
 159                 {
 160                 dti = tvb_get_uint8( tvb, offset );
 161                 if ( isaprs( dti ) )
 162                         snprintf( info_buffer, STRLEN, "APRS" );
 163                 }
 164         if ( gPREF_DX )
 165                 {
 166                 if ( tvb_get_uint8( tvb, offset ) == 'D' && tvb_get_uint8( tvb, offset + 1 ) == 'X' )
 167                 snprintf( info_buffer, STRLEN, "DX cluster" );
 168                 }
 169
 170         col_add_str( pinfo->cinfo, COL_INFO, info_buffer );
 171
 172         /* Call sub-dissectors here */
 173
 174         /* create display subtree for the protocol */
 175         ti = proto_tree_add_protocol_format( parent_tree,
 176                                                 proto_ax25_nol3,
 177                                                 tvb,
 178                                                 0,
 179                                                 -1,
 180                                                 "AX.25 No Layer 3 - (%s)", info_buffer );
 181         ax25_nol3_tree = proto_item_add_subtree( ti, ett_ax25_nol3 );
 182
 183         next_tvb = tvb_new_subset_remaining(tvb, offset);
 184         dissected = false;
 185         if ( gPREF_APRS )
 186                 {
 187                 if ( isaprs( dti ) )
 188                         {
 189                         dissected = true;
 190                         call_dissector( aprs_handle , next_tvb, pinfo, ax25_nol3_tree );
 191                         }
 192                 }
 193         if ( gPREF_DX )
 194                 {
 195                 if ( tvb_get_uint8( tvb, offset ) == 'D' && tvb_get_uint8( tvb, offset + 1 ) == 'X' )
 196                         {
 197                         dissected = true;
 198                         dissect_dx( next_tvb, pinfo, ax25_nol3_tree, NULL );
 199                         }
 200                 }
 201         if ( ! dissected )
 202                 call_data_dissector(next_tvb, pinfo, ax25_nol3_tree );
 203
 204         return tvb_captured_length(tvb);
 205 }
 206
 207 void
 208 proto_register_ax25_nol3(void)
 209 {
 210         module_t *ax25_nol3_module;
 211
 212         /* Setup list of header fields */
 213 #if 0 /* not used ? */
 214         static hf_register_info hf[] = {
 215                 { &hf_text,
 216                         { "Text",                       "ax25_nol3.text",
 217                         FT_STRING, BASE_NONE, NULL, 0x0,
 218                         NULL, HFILL }
 219                 },
 220         };
 221 #endif
 222
 223         static hf_register_info hf_dx[] = {
 224                 { &hf_dx_report,
 225                         { "DX",                         "ax25_nol3.dx",
 226                         FT_STRING, BASE_NONE, NULL, 0x0,
 227                         "DX cluster", HFILL }
 228                 },
 229         };
 230
 231         /* Setup protocol subtree array */
 232         static int *ett[] = {
 233                 &ett_ax25_nol3,
 234                 &ett_dx,
 235         };
 236
 237         /* Register the protocol name and description */
 238         proto_ax25_nol3 = proto_register_protocol("AX.25 no Layer 3", "AX.25 no L3", "ax25_nol3");
 239
 240         /* Required function calls to register the header fields and subtrees used */
 241         /* proto_register_field_array( proto_ax25_nol3, hf, array_length(hf ) ); */
 242         proto_register_subtree_array( ett, array_length( ett ) );
 243
 244         /* Register preferences module */
 245         ax25_nol3_module = prefs_register_protocol( proto_ax25_nol3, NULL);
 246
 247         /* Register any preference */
 248         prefs_register_bool_preference(ax25_nol3_module, "showaprs",
 249              "Decode the APRS info field",
 250              "Enable decoding of the payload as APRS.",
 251              &gPREF_APRS );
 252
 253         prefs_register_bool_preference(ax25_nol3_module, "showcluster",
 254              "Decode DX cluster info field",
 255              "Enable decoding of the payload as DX cluster info.",
 256              &gPREF_DX );
 257
 258         /* Register the sub-protocol name and description */
 259         proto_dx = proto_register_protocol("DX cluster", "DX", "dx");
 260
 261         /* Register the dissector */
 262         register_dissector( "dx", dissect_dx, proto_dx);
 263
 264         /* Register the header fields */
 265         proto_register_field_array( proto_dx, hf_dx, array_length( hf_dx ) );
 266
 267         /* Register the subtrees used */
 268         /* proto_register_subtree_array( ett_dx, array_length( ett_dx ) ); */
 269 }
 270
 271 void
 272 proto_reg_handoff_ax25_nol3(void)
 273 {
 274         dissector_add_uint( "ax25.pid", AX25_P_NO_L3, create_dissector_handle( dissect_ax25_nol3, proto_ax25_nol3 ) );
 275
 276         /*
 277          */
 278         aprs_handle     = find_dissector_add_dependency( "aprs", proto_ax25_nol3 );
 279 }
 280
 281 /*
 282  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 283  *
 284  * Local variables:
 285  * c-basic-offset: 8
 286  * tab-width: 8
 287  * indent-tabs-mode: t
 288  * End:
 289  *
 290  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 291  * :indentSize=8:tabSize=8:noTabs=false:
 292  */