nexmon – Rev 1
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/** Decode IrDA Serial Infrared (SIR) wrapped packets.
* @author Shaun Jackman <sjackman@debian.org>
* @copyright Copyright 2004 Shaun Jackman
* @license GPL
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/crc16-tvb.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)
void proto_reg_handoff_irsir(void);
void proto_register_irsir(void);
/** Protocol handles. */
static 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_status = -1;
static int hf_sir_length = -1;
static int hf_sir_preamble = -1;
/* Copied and renamed from proto.c because global value_strings don't work for plugins */
static const value_string plugin_proto_checksum_vals[] = {
{ PROTO_CHECKSUM_E_BAD, "Bad" },
{ PROTO_CHECKSUM_E_GOOD, "Good" },
{ PROTO_CHECKSUM_E_UNVERIFIED, "Unverified" },
{ PROTO_CHECKSUM_E_NOT_PRESENT, "Not present" },
{ 0, NULL }
};
/** 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 {
guint length = tvb_captured_length(tvb);
guint offset;
guint8 *data = (guint8 *)g_malloc(length);
guint8 *dst = data;
tvbuff_t *next_tvb;
for (offset = 0; offset < length; )
{
guint8 c = tvb_get_guint8(tvb, offset++);
if ((c == SIR_CE) && (offset < length))
c = SIR_ESCAPE(tvb_get_guint8(tvb, offset++));
*dst++ = c;
}
next_tvb = tvb_new_child_real_data(tvb, data, (guint) (dst-data), (guint) (dst-data));
tvb_set_free_cb(next_tvb, g_free);
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_reported_length(tvb) - 2;
if (len < 0)
return tvb;
proto_tree_add_checksum(tree, tvb, len, hf_sir_fcs, hf_sir_fcs_status, NULL, NULL, crc16_ccitt_tvb(tvb, len),
ENC_LITTLE_ENDIAN, PROTO_CHECKSUM_VERIFY);
return tvb_new_subset_length(tvb, 0, len);
}
/** Dissects an SIR packet. */
static int
dissect_sir(tvbuff_t *tvb, packet_info *pinfo, proto_tree *root, void* data _U_)
{
gint offset = 0;
gint bof_offset;
gint eof_offset;
while (tvb_reported_length_remaining(tvb, offset) > 0) {
bof_offset = tvb_find_guint8(tvb, offset, -1, SIR_BOF);
eof_offset = (bof_offset == -1) ? -1 :
tvb_find_guint8(tvb, bof_offset, -1, SIR_EOF);
if (bof_offset == -1 || eof_offset == -1) {
if (pinfo->can_desegment) {
pinfo->desegment_offset = offset;
pinfo->desegment_len = 1;
}
return tvb_captured_length(tvb);
} else {
guint preamble_len = bof_offset - offset;
gint data_offset = bof_offset + 1;
tvbuff_t* next_tvb = tvb_new_subset(tvb,
data_offset, eof_offset - data_offset, -1);
next_tvb = unescape_data(next_tvb, pinfo);
if (root) {
guint data_len = tvb_reported_length(next_tvb) < 2 ? 0 :
tvb_reported_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, ENC_NA);
proto_tree_add_item(tree, hf_sir_bof, tvb,
bof_offset, 1, ENC_BIG_ENDIAN);
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, ENC_BIG_ENDIAN);
} else {
next_tvb = checksum_data(next_tvb, NULL);
}
call_dissector(irda_handle, next_tvb, pinfo, root);
}
offset = eof_offset + 1;
}
return tvb_captured_length(tvb);
}
/** Registers this dissector with the parent dissector. */
void
proto_reg_handoff_irsir(void)
{
dissector_add_uint("tcp.port", TCP_PORT_SIR, find_dissector("sir"));
irda_handle = find_dissector("irda");
}
/** 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,
NULL, HFILL }},
#if 0
{ &hf_sir_ce,
{ "Command escape", "sir.ce",
FT_UINT8, BASE_HEX, NULL, 0,
NULL, HFILL }},
#endif
{ &hf_sir_eof,
{ "End of frame", "sir.eof",
FT_UINT8, BASE_HEX, NULL, 0,
NULL, HFILL }},
{ &hf_sir_fcs,
{ "Frame check sequence", "sir.fcs",
FT_UINT16, BASE_HEX, NULL, 0,
NULL, HFILL }},
{ &hf_sir_fcs_status,
{ "Frame check sequence Status", "sir.fcs.status",
FT_UINT8, BASE_NONE, VALS(plugin_proto_checksum_vals), 0x0,
NULL, HFILL }},
{ &hf_sir_length,
{ "Length", "sir.length",
FT_UINT16, BASE_DEC, NULL, 0,
NULL, HFILL }},
{ &hf_sir_preamble,
{ "Preamble", "sir.preamble",
FT_BYTES, BASE_NONE, NULL, 0,
NULL, 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));
}
/*
* Editor modelines - http://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:
*/