text: /* packet-ax25-nol3.c
   *
   * Routines for Amateur Packet Radio protocol dissection
   * Copyright 2007,2008,2009,2010,2012 R.W. Stearn <richard@rns-stearn.demon.co.uk>
   *
   * Wireshark - Network traffic analyzer
   * By Gerald Combs <gerald@wireshark.org>
   * Copyright 1998 Gerald Combs
   *
   * SPDX-License-Identifier: GPL-2.0-or-later
   */
  
  /*
   * This dissector is for the "No Layer 3 protocol" PID of the AX.25 Amateur
   * Packet-Radio Link-Layer Protocol, Version 2.0, October 1984
   *
   * At the time of writing the specification could be found here:
   *   http://www.tapr.org/pub_ax25.html
   *
   * Information on the "protocols" recognised by this dissector are drawn from:
   *  DX cluster:
   *    A network capture kindly donated by Luca Melette.
   *  APRS:
   *    http://www.aprs.org/
   *
   * Inspiration on how to build the dissector drawn from
   *   packet-sdlc.c
   *   packet-x25.c
   *   packet-lapb.c
   *   paket-gprs-llc.c
   *   xdlc.c
   * with the base file built from README.developers.
   */
  
  #include "config.h"
  
  #include <epan/packet.h>
  #include <epan/prefs.h>
  #include <epan/ax25_pids.h>
  
  #define STRLEN	80
  
  void proto_register_ax25_nol3(void);
  void proto_reg_handoff_ax25_nol3(void);
  
  /* Dissector handles - all the possibles are listed */
  static dissector_handle_t aprs_handle;
  
  /* Initialize the protocol and registered fields */
  static int proto_ax25_nol3		= -1;
  static int proto_dx			= -1;
  
  static int hf_dx_report			= -1;
  
  /* static int hf_text			= -1; */
  
  /* Global preferences */
  static gboolean gPREF_APRS     = FALSE;
  static gboolean gPREF_DX       = FALSE;
  
  /* Initialize the subtree pointers */
  static gint ett_ax25_nol3 = -1;
  
  static gint ett_dx		= -1;
  
  
  /* Code to actually dissect the packets */
  static int
  dissect_dx(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_)
  {
  	proto_item *ti;
  	proto_tree *dx_tree;
  
  	int data_len;
  	int offset;
  
  	offset   = 0;
  	data_len = tvb_reported_length_remaining( tvb, offset );
  
  	col_set_str( pinfo->cinfo, COL_PROTOCOL, "DX" );
  
  	col_add_fstr( pinfo->cinfo, COL_INFO, "%s", tvb_format_text( tvb, offset, 15 ) );
  
  	if ( parent_tree )
  		{
  		/* create display subtree for the protocol */
  		ti = proto_tree_add_protocol_format( parent_tree, proto_dx, tvb, 0, -1,
  		    "DX (%s)", tvb_format_text( tvb, offset, 15 ) );
  		dx_tree = proto_item_add_subtree( ti, ett_dx );
  		offset = 0;
  
  		proto_tree_add_item( dx_tree, hf_dx_report, tvb, offset, data_len, ENC_ASCII|ENC_NA );
  	}
  
  	return tvb_captured_length(tvb);
  }
  
  static gboolean
  isaprs( guint8 dti )
  {
  	gboolean b = FALSE;
  
  	switch ( dti )
  		{
  		case 0x1c	:
  		case 0x1d	:
  		case '!'	:
  		case '#'	:
  		case '$'	:
  		case '%'	:
  		case '&'	:
  		case ')'	:
  		case '*'	:
  		case '+'	:
  		case ','	:
  		case '.'	:
  		case '/'	:
  		case ':'	:
  		case ';'	:
  		case '<'	:
  		case '='	:
  		case '>'	:
  		case '?'	:
  		case '@'	:
  		case 'T'	:
  		case '['	:
  		case '\''	:
  		case '_'	:
  		case '`'	:
  		case '{'	:
  		case '}'	: b = TRUE; break;
  		default		: break;
  		}
  	return b;
  }
  
  static int
  dissect_ax25_nol3(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_ )
  {
  	proto_item *ti;
  	proto_tree *ax25_nol3_tree;
  	char       *info_buffer;
  	int         offset;
  	tvbuff_t   *next_tvb = NULL;
  	guint8      dti      = 0;
  	gboolean    dissected;
  
  	info_buffer = (char *)wmem_alloc( wmem_packet_scope(), STRLEN );
  	info_buffer[0] = '\0';
  
  	col_set_str( pinfo->cinfo, COL_PROTOCOL, "AX.25-NoL3");
  
  	col_clear( pinfo->cinfo, COL_INFO);
  
  	offset = 0;
  	g_snprintf( info_buffer, STRLEN, "Text" );
  
  	if ( gPREF_APRS )
  		{
  		dti = tvb_get_guint8( tvb, offset );
  		if ( isaprs( dti ) )
  			g_snprintf( info_buffer, STRLEN, "APRS" );
  		}
  	if ( gPREF_DX )
  		{
  		if ( tvb_get_guint8( tvb, offset ) == 'D' && tvb_get_guint8( tvb, offset + 1 ) == 'X' )
  		g_snprintf( info_buffer, STRLEN, "DX cluster" );
  		}
  
  	col_add_str( pinfo->cinfo, COL_INFO, info_buffer );
  
  	/* Call sub-dissectors here */
  
  	/* create display subtree for the protocol */
  	ti = proto_tree_add_protocol_format( parent_tree,
  						proto_ax25_nol3,
  						tvb,
  						0,
  						-1,
  						"AX.25 No Layer 3 - (%s)", info_buffer );
  	ax25_nol3_tree = proto_item_add_subtree( ti, ett_ax25_nol3 );
  
  	next_tvb = tvb_new_subset_remaining(tvb, offset);
  	dissected = FALSE;
  	if ( gPREF_APRS )
  		{
  		if ( isaprs( dti ) )
  			{
  			dissected = TRUE;
  			call_dissector( aprs_handle , next_tvb, pinfo, ax25_nol3_tree );
  			}
  		}
  	if ( gPREF_DX )
  		{
  		if ( tvb_get_guint8( tvb, offset ) == 'D' && tvb_get_guint8( tvb, offset + 1 ) == 'X' )
  			{
  			dissected = TRUE;
  			dissect_dx( next_tvb, pinfo, ax25_nol3_tree, NULL );
  			}
  		}
  	if ( ! dissected )
  		call_data_dissector(next_tvb, pinfo, ax25_nol3_tree );
  
  	return tvb_captured_length(tvb);
  }
  
  void
  proto_register_ax25_nol3(void)
  {
  	module_t *ax25_nol3_module;
  
  	/* Setup list of header fields */
  #if 0 /* not used ? */
  	static hf_register_info hf[] = {
  		{ &hf_text,
  			{ "Text",			"ax25_nol3.text",
  			FT_STRING, BASE_NONE, NULL, 0x0,
  			NULL, HFILL }
  		},
  	};
  #endif
  
  	static hf_register_info hf_dx[] = {
  		{ &hf_dx_report,
  			{ "DX",				"ax25_nol3.dx",
  			FT_STRING, BASE_NONE, NULL, 0x0,
  			"DX cluster", HFILL }
  		},
  	};
  
  	/* Setup protocol subtree array */
  	static gint *ett[] = {
  		&ett_ax25_nol3,
  		&ett_dx,
  	};
  
  	/* Register the protocol name and description */
  	proto_ax25_nol3 = proto_register_protocol("AX.25 no Layer 3", "AX.25 no L3", "ax25_nol3");
  
  	/* Required function calls to register the header fields and subtrees used */
  	/* proto_register_field_array( proto_ax25_nol3, hf, array_length(hf ) ); */
  	proto_register_subtree_array( ett, array_length( ett ) );
  
  	/* Register preferences module */
  	ax25_nol3_module = prefs_register_protocol( proto_ax25_nol3, NULL);
  
  	/* Register any preference */
  	prefs_register_bool_preference(ax25_nol3_module, "showaprs",
  	     "Decode the APRS info field",
  	     "Enable decoding of the payload as APRS.",
  	     &gPREF_APRS );
  
  	prefs_register_bool_preference(ax25_nol3_module, "showcluster",
  	     "Decode DX cluster info field",
  	     "Enable decoding of the payload as DX cluster info.",
  	     &gPREF_DX );
  
  	/* Register the sub-protocol name and description */
  	proto_dx = proto_register_protocol("DX cluster", "DX", "dx");
  
  	/* Register the dissector */
  	register_dissector( "dx", dissect_dx, proto_dx);
  
  	/* Register the header fields */
  	proto_register_field_array( proto_dx, hf_dx, array_length( hf_dx ) );
  
  	/* Register the subtrees used */
  	/* proto_register_subtree_array( ett_dx, array_length( ett_dx ) ); */
  }
  
  void
  proto_reg_handoff_ax25_nol3(void)
  {
  	dissector_add_uint( "ax25.pid", AX25_P_NO_L3, create_dissector_handle( dissect_ax25_nol3, proto_ax25_nol3 ) );
  
  	/*
  	 */
  	aprs_handle     = find_dissector_add_dependency( "aprs", proto_ax25_nol3 );
  }
  
  /*
   * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
   *
   * Local variables:
   * c-basic-offset: 8
   * tab-width: 8
   * indent-tabs-mode: t
   * End:
   *
   * vi: set shiftwidth=8 tabstop=8 noexpandtab:
   * :indentSize=8:tabSize=8:noTabs=false:
   */
  