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/* 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( pinfo->pool, 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( pinfo->pool, 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 );
}
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( pinfo->pool, STRLEN );
info_buffer[0] = '\0';
col_set_str( pinfo->cinfo, COL_PROTOCOL, "AX.25-NoL3");
col_clear( pinfo->cinfo, COL_INFO);
offset = 0;
snprintf( info_buffer, STRLEN, "Text" );
if ( gPREF_APRS )
{
dti = tvb_get_guint8( tvb, offset );
if ( isaprs( dti ) )
snprintf( info_buffer, STRLEN, "APRS" );
}
if ( gPREF_DX )
{
if ( tvb_get_guint8( tvb, offset ) == 'D' && tvb_get_guint8( tvb, offset + 1 ) == 'X' )
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:
*/
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