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wireshark/epan/dissectors/packet-ax25-kiss.c

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/* packet-ax25-kiss.c
*
* Routines for AX.25 KISS protocol dissection
* Copyright 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
*
* 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.
*/
/*
* This dissector handles the "KISS" protocol as implemented by the
* Linux kernel.
*
* The original definition of the KISS protocol can be found here:
* http://www.ka9q.net/papers/kiss.html
* and here:
* http://www.ax25.net/kiss.aspx
*
* The Linux implementation does not appear to attempt to implement that
* protocol in full. It does provide the ability to send a KISS command via
* ax25_kiss_cmd() and internally will send FULLDUPLEX KISS commands if
* DAMA is enabled/disabled.
* i.e.:
* ax25_dev_dama_on sends FullDuplex ON
* ax25_dev_dama_off sends FullDuplex OFF
*
* Data frames are prefixed with a "Data Frame" command but the port appears to
* be always 0.
*
* Abstract from http://www.ka9q.net/papers/kiss.html
* --------------------------------------------------
* For reference the first byte of a KISS frame is the frame type and the TNC
* port number,
* LSB 4 bits = frame type,
* MSB 4 bits = port number.
*
* The frame types are:
* Command Function Comments
* 0 Data frame The rest of the frame is data to
* be sent on the HDLC channel.
*
* 1 TXDELAY The next byte is the transmitter
* keyup delay in 10 ms units.
* The default start-up value is 50
* (i.e., 500 ms).
*
* 2 P The next byte is the persistence
* parameter, p, scaled to the range
* 0 - 255 with the following
* formula:
*
* P = p * 256 - 1
*
* The default value is P = 63
* (i.e., p = 0.25).
*
* 3 SlotTime The next byte is the slot interval
* in 10 ms units.
* The default is 10 (i.e., 100ms).
*
* 4 TXtail The next byte is the time to hold
* up the TX after the FCS has been
* sent, in 10 ms units. This command
* is obsolete, and is included here
* only for compatibility with some
* existing implementations.
*
* 5 FullDuplex The next byte is 0 for half duplex,
* nonzero for full duplex.
* The default is 0
* (i.e., half duplex).
*
* 6 SetHardware Specific for each TNC. In the
* TNC-1, this command sets the
* modem speed. Other implementations
* may use this function for other
* hardware-specific functions.
*
* FF Return Exit KISS and return control to a
* higher-level program. This is useful
* only when KISS is incorporated
* into the TNC along with other
* applications.
*
*
* G8BPQ extensions:
*
* 12 Data frame Data with acknowledge request
*
* 14 Poll mode Set poll mode
*
* Checksum mode
*
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/capture_dissectors.h>
#include <epan/prefs.h>
#include <wiretap/wtap.h>
#include "packet-ax25.h"
#define STRLEN 80
#define KISS_HEADER_SIZE 1 /* length of the KISS type header */
/* KISS frame types */
#define KISS_DATA_FRAME 0
#define KISS_TXDELAY 1
#define KISS_PERSISTENCE 2
#define KISS_SLOT_TIME 3
#define KISS_TXTAIL 4
#define KISS_FULLDUPLEX 5
#define KISS_SETHARDWARE 6
#define KISS_DATA_FRAME_ACK 12
#define KISS_POLL_MODE 14
#define KISS_RETURN 15
#define KISS_CMD_MASK 0x0f
#define KISS_PORT_MASK 0xf0
/* Global preferences */
static gboolean gPREF_CKSUM_MODE = FALSE;
void proto_register_ax25_kiss(void);
void proto_reg_handoff_ax25_kiss(void);
/* Initialize the protocol and registered fields */
static int proto_ax25_kiss = -1;
static int hf_ax25_kiss_cmd = -1;
static int hf_ax25_kiss_port = -1;
static int hf_ax25_kiss_txdelay = -1;
static int hf_ax25_kiss_persistence = -1;
static int hf_ax25_kiss_slottime = -1;
static int hf_ax25_kiss_txtail = -1;
static int hf_ax25_kiss_fullduplex = -1;
static int hf_ax25_kiss_sethardware = -1;
static int hf_ax25_kiss_data_ack = -1;
static int hf_ax25_kiss_cksum = -1;
/* Initialize the subtree pointers */
static gint ett_ax25_kiss = -1;
static dissector_handle_t kiss_handle;
/* Dissector handles - all the possibles are listed */
static dissector_handle_t ax25_handle;
static const value_string kiss_frame_types[] = {
{ KISS_DATA_FRAME, "Data frame" },
{ KISS_TXDELAY, "Tx delay" },
{ KISS_PERSISTENCE, "Persistence" },
{ KISS_SLOT_TIME, "Slot time" },
{ KISS_TXTAIL, "Tx tail" },
{ KISS_FULLDUPLEX, "Full duplex" },
{ KISS_SETHARDWARE, "Set hardware" },
{ KISS_DATA_FRAME_ACK, "Data frame ack" },
{ KISS_POLL_MODE, "Poll mode" },
{ KISS_RETURN, "Return" },
{ 0, NULL }
};
static gboolean
capture_ax25_kiss( const guchar *pd, int offset, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header)
{
int l_offset;
guint8 kiss_cmd;
if ( ! BYTES_ARE_IN_FRAME( offset, len, KISS_HEADER_SIZE ) )
return FALSE;
l_offset = offset;
kiss_cmd = pd[ l_offset ];
l_offset += KISS_HEADER_SIZE; /* step over kiss header */
switch ( kiss_cmd & KISS_CMD_MASK )
{
case KISS_DATA_FRAME :
return capture_ax25( pd, l_offset, len, cpinfo, pseudo_header );
case KISS_TXDELAY : break;
case KISS_PERSISTENCE : break;
case KISS_SLOT_TIME : break;
case KISS_TXTAIL : break;
case KISS_FULLDUPLEX : break;
case KISS_SETHARDWARE : break;
case KISS_DATA_FRAME_ACK:
l_offset += 2;
return capture_ax25( pd, l_offset, len, cpinfo, pseudo_header );
case KISS_POLL_MODE : break;
case KISS_RETURN : break;
default : break;
}
return FALSE;
}
/* Code to actually dissect the packets */
static int
dissect_ax25_kiss( tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_ )
{
proto_item *ti;
proto_tree *kiss_tree;
int offset;
int kiss_cmd;
int kiss_type;
int kiss_port;
int kiss_param;
int kiss_param_len;
int kiss_cksum;
int kiss_cksum_index;
int kiss_tvb_length;
const char *frame_type_text;
char *info_buffer;
tvbuff_t *next_tvb = NULL;
info_buffer = (char *)wmem_alloc( wmem_packet_scope(), STRLEN );
info_buffer[0] = '\0';
col_set_str( pinfo->cinfo, COL_PROTOCOL, "AX.25 KISS" );
col_clear( pinfo->cinfo, COL_INFO );
/* protocol offset for the KISS header */
offset = 0;
kiss_cmd = tvb_get_guint8( tvb, offset ) & 0xff;
kiss_type = kiss_cmd & KISS_CMD_MASK;
kiss_port = (kiss_cmd & KISS_PORT_MASK) >> 4;
offset += KISS_HEADER_SIZE;
kiss_param = 0;
kiss_param_len = 0;
switch ( kiss_type )
{
case KISS_TXDELAY : kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
case KISS_PERSISTENCE : kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
case KISS_SLOT_TIME : kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
case KISS_TXTAIL : kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
case KISS_FULLDUPLEX : kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
case KISS_SETHARDWARE :
kiss_param_len = tvb_captured_length_remaining( tvb, offset );
if ( kiss_param_len < 0 )
kiss_param_len = 0;
if ( (kiss_param_len > 0) && gPREF_CKSUM_MODE )
kiss_param_len--;
break;
case KISS_DATA_FRAME_ACK: kiss_param_len = 2; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
default : break;
}
frame_type_text = val_to_str(kiss_type, kiss_frame_types, "Unknown (%u)");
g_snprintf( info_buffer, STRLEN, "%s, Port %u", frame_type_text, kiss_port );
if ( kiss_param_len > 0 )
g_snprintf( info_buffer, STRLEN, "%s %u, Port %u", frame_type_text, kiss_param, kiss_port );
offset += kiss_param_len;
col_add_str( pinfo->cinfo, COL_INFO, info_buffer );
if ( parent_tree )
{
/* protocol offset for the KISS header */
offset = 0;
/* create display subtree for the protocol */
ti = proto_tree_add_protocol_format( parent_tree, proto_ax25_kiss, tvb, offset,
tvb_captured_length_remaining( tvb, offset ),
"KISS: %s",
info_buffer
);
kiss_tree = proto_item_add_subtree( ti, ett_ax25_kiss );
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_cmd, tvb, offset, KISS_HEADER_SIZE,
kiss_cmd );
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_port, tvb, offset, KISS_HEADER_SIZE,
kiss_port );
offset += KISS_HEADER_SIZE;
switch ( kiss_type )
{
case KISS_DATA_FRAME : break;
case KISS_TXDELAY :
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_txdelay,
tvb, offset, kiss_param_len, kiss_param );
offset += kiss_param_len;
break;
case KISS_PERSISTENCE :
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_persistence,
tvb, offset, kiss_param_len, kiss_param );
offset += kiss_param_len;
break;
case KISS_SLOT_TIME :
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_slottime,
tvb, offset, kiss_param_len, kiss_param );
offset += kiss_param_len;
break;
case KISS_TXTAIL :
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_txtail,
tvb, offset, kiss_param_len, kiss_param );
offset += kiss_param_len;
break;
case KISS_FULLDUPLEX :
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_fullduplex,
tvb, offset, kiss_param_len, kiss_param );
offset += kiss_param_len;
break;
case KISS_SETHARDWARE :
proto_tree_add_item( kiss_tree, hf_ax25_kiss_sethardware,
tvb, offset, kiss_param_len, ENC_NA );
offset += kiss_param_len;
break;
case KISS_DATA_FRAME_ACK:
proto_tree_add_uint( kiss_tree, hf_ax25_kiss_data_ack,
tvb, offset, kiss_param_len, kiss_param );
offset += kiss_param_len;
break;
case KISS_POLL_MODE : break;
case KISS_RETURN : break;
default : break;
}
if ( gPREF_CKSUM_MODE )
{
kiss_cksum = 0;
kiss_tvb_length = tvb_captured_length(tvb) - 1;
if ( kiss_tvb_length > 0 )
{
for ( kiss_cksum_index = 0; kiss_cksum_index < kiss_tvb_length; kiss_cksum_index++ )
kiss_cksum ^= (tvb_get_guint8( tvb, kiss_cksum_index ) & 0xff);
proto_tree_add_checksum(kiss_tree, tvb, 0, hf_ax25_kiss_cksum, -1, NULL, pinfo, kiss_cksum, ENC_NA, PROTO_CHECKSUM_GENERATED);
}
}
}
/* Call sub-dissectors here */
if ( ( kiss_type == KISS_DATA_FRAME ) || ( kiss_type == KISS_DATA_FRAME_ACK ) )
{
next_tvb = tvb_new_subset_remaining( tvb, offset );
call_dissector( ax25_handle, next_tvb, pinfo, parent_tree );
}
return tvb_captured_length(tvb);
}
void
proto_register_ax25_kiss(void)
{
module_t *ax25_kiss_module;
/* Setup list of header fields */
static hf_register_info hf[] = {
{ &hf_ax25_kiss_cmd,
{ "Cmd", "ax25_kiss.cmd",
FT_UINT8, BASE_DEC, VALS(kiss_frame_types), KISS_CMD_MASK,
NULL, HFILL }
},
{ &hf_ax25_kiss_port,
{ "Port", "ax25_kiss.port",
FT_UINT8, BASE_DEC, NULL, KISS_PORT_MASK,
NULL, HFILL }
},
{ &hf_ax25_kiss_txdelay,
{ "Tx delay", "ax25_kiss.txdelay",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ax25_kiss_persistence,
{ "Persistence", "ax25_kiss.persistence",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ax25_kiss_slottime,
{ "Slot time", "ax25_kiss.slottime",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ax25_kiss_txtail,
{ "Tx tail", "ax25_kiss.txtail",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ax25_kiss_fullduplex,
{ "Full duplex", "ax25_kiss.fullduplex",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ax25_kiss_sethardware,
{ "Set hardware", "ax25_kiss.sethardware",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ax25_kiss_data_ack,
{ "Data ack", "ax25_kiss.data_ack",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_ax25_kiss_cksum,
{ "Checksum", "ax25_kiss.cksum",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
};
/* Setup protocol subtree array */
static gint *ett[] = {
&ett_ax25_kiss,
};
/* Register the protocol name and description */
proto_ax25_kiss = proto_register_protocol( "AX.25 KISS", "AX.25 KISS", "ax25_kiss" );
/* Register the dissector */
kiss_handle = register_dissector( "ax25_kiss", dissect_ax25_kiss, proto_ax25_kiss );
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array( proto_ax25_kiss, hf, array_length( hf ) );
proto_register_subtree_array( ett, array_length( ett ) );
/* Register preferences module */
ax25_kiss_module = prefs_register_protocol( proto_ax25_kiss, NULL);
prefs_register_bool_preference(ax25_kiss_module, "showcksum",
"Set checksum mode",
"Enable checksum calculation.",
&gPREF_CKSUM_MODE );
}
void
proto_reg_handoff_ax25_kiss(void)
{
dissector_add_uint( "wtap_encap", WTAP_ENCAP_AX25_KISS, kiss_handle );
register_capture_dissector("wtap_encap", WTAP_ENCAP_AX25_KISS, capture_ax25_kiss, proto_ax25_kiss);
/* only currently implemented for AX.25 */
ax25_handle = find_dissector_add_dependency( "ax25", proto_ax25_kiss );
}
/*
* 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:
*/
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