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/** Decode IrDA Serial Infrared (SIR) wrapped packets.
* @author Shaun Jackman <sjackman@debian.org>
* @copyright Copyright 2004 Shaun Jackman
* @license GPL
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "moduleinfo.h"
#include "plugins/plugin_api.h"
#include <epan/crc16.h>
#include <gmodule.h>
/** Serial infrared port. */
#define TCP_PORT_SIR 6417
/** Beginning of frame. */
#define SIR_BOF 0xc0
/** End of frame. */
#define SIR_EOF 0xc1
/** Control escape. */
#define SIR_CE 0x7d
/** Escapes this character. */
#define SIR_ESCAPE(x) ((x)^0x20)
/** Protocol handles. */
dissector_handle_t data_handle;
dissector_handle_t irda_handle;
/** Protocol fields. */
static int proto_sir = -1;
static int ett_sir = -1;
static int hf_sir_bof = -1;
static int hf_sir_ce = -1;
static int hf_sir_eof = -1;
static int hf_sir_fcs = -1;
static int hf_sir_fcs_bad = -1;
static int hf_sir_length = -1;
static int hf_sir_preamble = -1;
/** Unescapes the data. */
static tvbuff_t*
unescape_data( tvbuff_t* tvb, packet_info* pinfo)
{
if( tvb_find_guint8( tvb, 0, -1, SIR_CE) == -1) {
return tvb;
} else {
guint8* data = g_malloc( tvb_length( tvb));
const guint8* src = tvb_get_ptr( tvb, 0, -1);
const guint8* end = src + tvb_length( tvb);
guint8* dst = data;
while( src < end) {
guint8 c = *src++;
switch( c) {
case SIR_CE:
if( src < end)
c = SIR_ESCAPE( *src++);
default:
*dst++ = c;
}
}
{
tvbuff_t* next_tvb = tvb_new_real_data(
data, dst-data, dst-data);
tvb_set_free_cb( next_tvb, g_free);
tvb_set_child_real_data_tvbuff( tvb, next_tvb);
add_new_data_source( pinfo, next_tvb, "Unescaped SIR");
return next_tvb;
}
}
}
/** Checksums the data. */
static tvbuff_t*
checksum_data( tvbuff_t* tvb, proto_tree* tree)
{
int len = tvb_length( tvb) - 2;
if( len < 0)
return tvb;
if( tree) {
guint16 actual_fcs = tvb_get_letohs( tvb, len);
guint16 calculated_fcs = crc16_ccitt_tvb( tvb, len);
if( calculated_fcs == actual_fcs) {
proto_tree_add_uint_format( tree, hf_sir_fcs,
tvb, len, 2, actual_fcs,
"Frame check sequence: 0x%04x (correct)",
actual_fcs);
} else {
proto_tree_add_boolean_hidden( tree,
hf_sir_fcs_bad, tvb, len, 2, TRUE);
proto_tree_add_uint_format( tree, hf_sir_fcs,
tvb, len, 2, actual_fcs,
"Frame check sequence: 0x%04x "
"(incorrect, should be 0x%04x)",
actual_fcs, calculated_fcs);
}
}
return tvb_new_subset( tvb, 0, len, len);
}
/** Dissects an SIR packet. */
static void
dissect_sir( tvbuff_t* tvb, packet_info* pinfo, proto_tree* root)
{
gint offset = 0;
while( tvb_length_remaining( tvb, offset) > 0) {
gint bof_offset = tvb_find_guint8( tvb, offset, -1, SIR_BOF);
guint preamble_len = bof_offset - offset;
gint eof_offset = bof_offset == -1 ? -1 :
tvb_find_guint8( tvb, bof_offset, -1, SIR_EOF);
gint data_offset = bof_offset + 1;
guint data_len = eof_offset - data_offset;
tvbuff_t* next_tvb = tvb_new_subset( tvb,
data_offset, data_len, -1);
if( bof_offset == -1 || eof_offset == -1) {
if( pinfo->can_desegment) {
pinfo->desegment_offset = offset;
pinfo->desegment_len = 1;
}
return;
} else {
next_tvb = unescape_data( next_tvb, pinfo);
if( root) {
unsigned data_len = tvb_length( next_tvb) < 2 ? 0 :
tvb_length( next_tvb) - 2;
proto_tree* ti = proto_tree_add_protocol_format( root,
proto_sir, tvb, offset, eof_offset - offset + 1,
"Serial Infrared, Len: %d", data_len);
proto_tree* tree = proto_item_add_subtree( ti, ett_sir);
if( preamble_len > 0)
proto_tree_add_item( tree, hf_sir_preamble, tvb,
offset, preamble_len, FALSE);
proto_tree_add_item( tree, hf_sir_bof, tvb,
bof_offset, 1, FALSE);
proto_tree_add_uint( tree, hf_sir_length,
next_tvb, 0, data_len, data_len);
next_tvb = checksum_data( next_tvb, tree);
proto_tree_add_item( tree, hf_sir_eof, tvb,
eof_offset, 1, FALSE);
} else
next_tvb = checksum_data( next_tvb, NULL);
call_dissector( irda_handle, next_tvb, pinfo, root);
}
offset = eof_offset + 1;
}
}
/** Registers this dissector with the parent dissector. */
static void
proto_reg_handoff_sir( void)
{
dissector_add( "tcp.port", TCP_PORT_SIR, find_dissector( "sir"));
data_handle = find_dissector( "data");
irda_handle = find_dissector( "irda");
if( irda_handle == 0)
irda_handle = data_handle;
}
/** Initializes this protocol. */
void
proto_register_irsir( void)
{
static gint* ett[] = { &ett_sir };
static hf_register_info hf_sir[] = {
{ &hf_sir_bof,
{ "Beginning of frame", "sir.bof",
FT_UINT8, BASE_HEX, NULL, 0,
"", HFILL }},
{ &hf_sir_ce,
{ "Command escape", "sir.ce",
FT_UINT8, BASE_HEX, NULL, 0,
"", HFILL }},
{ &hf_sir_eof,
{ "End of frame", "sir.eof",
FT_UINT8, BASE_HEX, NULL, 0,
"", HFILL }},
{ &hf_sir_fcs,
{ "Frame check sequence", "sir.fcs",
FT_UINT16, BASE_HEX, NULL, 0,
"", HFILL }},
{ &hf_sir_fcs_bad,
{ "Bad frame check sequence", "sir.fcs_bad",
FT_BOOLEAN, BASE_NONE, NULL, 0,
"", HFILL }},
{ &hf_sir_length,
{ "Length", "sir.length",
FT_UINT16, BASE_DEC, NULL, 0,
"", HFILL }},
{ &hf_sir_preamble,
{ "Preamble", "sir.preamble",
FT_BYTES, BASE_NONE, NULL, 0,
"", HFILL }},
};
proto_sir = proto_register_protocol(
"Serial Infrared", "SIR", "sir");
register_dissector( "sir", dissect_sir, proto_sir);
proto_register_subtree_array( ett, array_length( ett));
proto_register_field_array(
proto_sir, hf_sir, array_length( hf_sir));
proto_reg_handoff_sir();
}
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