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 = -1; 51 static int proto_dx = -1; 52 53 static int hf_dx_report = -1; 54 55 /* static int hf_text = -1; */ 56 57 /* Global preferences */ 58 static gboolean gPREF_APRS = FALSE; 59 static gboolean gPREF_DX = FALSE; 60 61 /* Initialize the subtree pointers */ 62 static gint ett_ax25_nol3 = -1; 63 64 static gint ett_dx = -1; 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_fstr( pinfo->cinfo, COL_INFO, "%s", 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|ENC_NA ); 93 } 94 95 return tvb_captured_length(tvb); 96 } 97 98 static gboolean 99 isaprs( guint8 dti ) 100 { 101 gboolean 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 guint8 dti = 0; 146 gboolean 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 g_snprintf( info_buffer, STRLEN, "Text" ); 157 158 if ( gPREF_APRS ) 159 { 160 dti = tvb_get_guint8( tvb, offset ); 161 if ( isaprs( dti ) ) 162 g_snprintf( info_buffer, STRLEN, "APRS" ); 163 } 164 if ( gPREF_DX ) 165 { 166 if ( tvb_get_guint8( tvb, offset ) == 'D' && tvb_get_guint8( tvb, offset + 1 ) == 'X' ) 167 g_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_guint8( tvb, offset ) == 'D' && tvb_get_guint8( 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 gint *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 */ 293