forked from osmocom/wireshark
405 lines
13 KiB
C
405 lines
13 KiB
C
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/* packet-ax25-kiss.c
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*
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* Routines for AX.25 KISS protocol dissection
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* Copyright 2010,2012 R.W. Stearn <richard@rns-stearn.demon.co.uk>
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*
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* $Id$
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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/*
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* This dissector handles the "KISS" protocol as implemented by the
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* Linux kernel.
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*
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* The original definition of the KISS protocol can be found here:
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* http://www.ka9q.net/papers/kiss.html
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* and here:
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* http://www.ax25.net/kiss.aspx
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*
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* Linux implementation does not appear to attempt to implement that
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* protocol in full. Does provide the ability to send a KISS command via
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* ax25_kiss_cmd() and internally will send FULLDUPLEX KISS commands if
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* DAMA is enabled/disabled.
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* i.e.:
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* ax25_dev_dama_on sends FullDuplex ON
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* ax25_dev_dama_off sends FullDuplex OFF
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*
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* Data frames are prefixed with a "Data Frame" command but the port appears to
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* be always 0.
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*
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* Abstract from http://www.ka9q.net/papers/kiss.html
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* --------------------------------------------------
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* For reference the first byte of a KISS frame is the frame type and the TNC
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* port number,
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* LSB 4 bits = frame type,
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* MSB 4 bits = port number.
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*
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* The frame types are:
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* Command Function Comments
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* 0 Data frame The rest of the frame is data to
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* be sent on the HDLC channel.
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*
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* 1 TXDELAY The next byte is the transmitter
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* keyup delay in 10 ms units.
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* The default start-up value is 50
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* (i.e., 500 ms).
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*
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* 2 P The next byte is the persistence
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* parameter, p, scaled to the range
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* 0 - 255 with the following
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* formula:
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*
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* P = p * 256 - 1
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*
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* The default value is P = 63
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* (i.e., p = 0.25).
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*
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* 3 SlotTime The next byte is the slot interval
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* in 10 ms units.
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* The default is 10 (i.e., 100ms).
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*
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* 4 TXtail The next byte is the time to hold
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* up the TX after the FCS has been
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* sent, in 10 ms units. This command
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* is obsolete, and is included here
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* only for compatibility with some
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* existing implementations.
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*
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* 5 FullDuplex The next byte is 0 for half duplex,
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* nonzero for full duplex.
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* The default is 0
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* (i.e., half duplex).
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*
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* 6 SetHardware Specific for each TNC. In the
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* TNC-1, this command sets the
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* modem speed. Other implementations
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* may use this function for other
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* hardware-specific functions.
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*
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* FF Return Exit KISS and return control to a
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* higher-level program. This is useful
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* only when KISS is incorporated
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* into the TNC along with other
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* applications.
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*
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <glib.h>
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#include <epan/strutil.h>
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#include <epan/packet.h>
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#include <epan/prefs.h>
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#include <epan/emem.h>
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#include <epan/etypes.h>
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#include "packet-ax25-kiss.h"
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#define STRLEN 80
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#define KISS_HEADER_SIZE 1 /* length of the KISS type header */
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/* KISS frame types */
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#define KISS_DATA_FRAME 0
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#define KISS_TXDELAY 1
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#define KISS_PERSISTENCE 2
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#define KISS_SLOT_TIME 3
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#define KISS_TXTAIL 4
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#define KISS_FULLDUPLEX 5
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#define KISS_SETHARDWARE 6
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#define KISS_RETURN 15
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#define KISS_CMD_MASK 0x0f
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#define KISS_PORT_MASK 0xf0
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/* Forward declaration we need below */
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void proto_reg_handoff_ax25_kiss(void);
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/* Dissector handles - all the possibles are listed */
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/* Initialize the protocol and registered fields */
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static int proto_ax25_kiss = -1;
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static int hf_ax25_kiss_cmd = -1;
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static int hf_ax25_kiss_port = -1;
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static int hf_ax25_kiss_txdelay = -1;
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static int hf_ax25_kiss_persistence = -1;
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static int hf_ax25_kiss_slottime = -1;
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static int hf_ax25_kiss_txtail = -1;
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static int hf_ax25_kiss_fullduplex = -1;
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static int hf_ax25_kiss_sethardware = -1;
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/* Global preference ("controls" display of numbers) */
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/*
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static gboolean gPREF_HEX = FALSE;
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*/
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/* Initialize the subtree pointers */
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static gint ett_ax25_kiss = -1;
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/* Code to actually dissect the packets */
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static void
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dissect_ax25_kiss( tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree )
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{
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proto_item *ti;
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proto_tree *kiss_tree;
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int offset;
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int kiss_cmd;
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int kiss_type;
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int kiss_port;
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int kiss_param;
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int kiss_param_len;
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char *frame_type_text;
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char *info_buffer;
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#if 0
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void *saved_private_data;
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tvbuff_t *next_tvb = NULL;
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#endif
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info_buffer = ep_alloc( STRLEN );
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info_buffer[0]='\0';
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if ( check_col( pinfo->cinfo, COL_PROTOCOL ) )
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col_set_str( pinfo->cinfo, COL_PROTOCOL, "KISS" );
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col_clear( pinfo->cinfo, COL_INFO );
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/* protocol offset for the KISS header */
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offset = 0;
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kiss_cmd = tvb_get_guint8( tvb, offset ) & 0xff;
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kiss_type = kiss_cmd & KISS_CMD_MASK;
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kiss_port = (kiss_cmd & KISS_PORT_MASK) >> 4;
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offset += KISS_HEADER_SIZE;
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frame_type_text = "????";
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kiss_param = 0;
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kiss_param_len = 0;
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switch ( kiss_type )
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{
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case KISS_DATA_FRAME : frame_type_text = "Data frame"; break;
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case KISS_TXDELAY : frame_type_text = "Tx Delay"; kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
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case KISS_PERSISTENCE : frame_type_text = "Persistence"; kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
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case KISS_SLOT_TIME : frame_type_text = "Slot time"; kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
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case KISS_TXTAIL : frame_type_text = "Tx tail"; kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
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case KISS_FULLDUPLEX : frame_type_text = "Full duplex"; kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
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case KISS_SETHARDWARE : frame_type_text = "Set hardware"; kiss_param_len = 1; kiss_param = tvb_get_guint8( tvb, offset ) & 0xff; break;
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case KISS_RETURN : frame_type_text = "Return"; break;
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default : break;
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}
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g_snprintf( info_buffer, STRLEN, "%s, Port %u", frame_type_text, kiss_port );
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if ( kiss_param_len > 0 )
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g_snprintf( info_buffer, STRLEN, "%s %u, Port %u", frame_type_text, kiss_param,
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kiss_port );
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offset += kiss_param_len;
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col_add_str( pinfo->cinfo, COL_INFO, info_buffer );
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if ( parent_tree )
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{
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/* protocol offset for the KISS header */
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offset = 0;
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/* create display subtree for the protocol */
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ti = proto_tree_add_protocol_format( parent_tree, proto_ax25_kiss, tvb, offset,
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KISS_HEADER_SIZE + kiss_param_len,
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"KISS: %s",
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info_buffer
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);
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kiss_tree = proto_item_add_subtree( ti, ett_ax25_kiss );
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_cmd, tvb, offset, KISS_HEADER_SIZE,
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kiss_cmd );
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_port, tvb, offset, KISS_HEADER_SIZE,
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kiss_cmd );
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offset += KISS_HEADER_SIZE;
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switch ( kiss_type )
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{
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case KISS_DATA_FRAME : break;
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case KISS_TXDELAY :
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_txdelay,
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tvb, offset, kiss_param_len, kiss_param );
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offset += kiss_param_len;
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break;
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case KISS_PERSISTENCE :
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_persistence,
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tvb, offset, kiss_param_len, kiss_param );
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offset += kiss_param_len;
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break;
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case KISS_SLOT_TIME :
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_slottime,
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tvb, offset, kiss_param_len, kiss_param );
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offset += kiss_param_len;
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break;
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case KISS_TXTAIL :
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_txtail,
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tvb, offset, kiss_param_len, kiss_param );
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offset += kiss_param_len;
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break;
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case KISS_FULLDUPLEX :
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_fullduplex,
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tvb, offset, kiss_param_len, kiss_param );
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offset += kiss_param_len;
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break;
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case KISS_SETHARDWARE :
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proto_tree_add_uint( kiss_tree, hf_ax25_kiss_sethardware,
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tvb, offset, kiss_param_len, kiss_param );
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offset += kiss_param_len;
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break;
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case KISS_RETURN : break;
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default : break;
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}
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}
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/* Call sub-dissectors here */
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}
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void
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proto_register_ax25_kiss(void)
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{
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module_t *ax25_kiss_module;
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/* Setup list of header fields */
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static hf_register_info hf[] = {
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{ &hf_ax25_kiss_cmd,
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{ "Cmd", "ax25_kiss.cmd",
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FT_UINT8, BASE_DEC, NULL, KISS_CMD_MASK,
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"Cmd", HFILL }
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},
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{ &hf_ax25_kiss_port,
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{ "Port", "ax25_kiss.port",
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FT_UINT8, BASE_DEC, NULL, KISS_PORT_MASK,
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"Port", HFILL }
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},
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{ &hf_ax25_kiss_txdelay,
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{ "Tx delay", "ax25_kiss.txdelay",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"Tx delay", HFILL }
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},
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{ &hf_ax25_kiss_persistence,
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{ "Persistence", "ax25_kiss.persistence",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"Persistence", HFILL }
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},
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{ &hf_ax25_kiss_slottime,
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{ "Slot time", "ax25_kiss.slottime",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"Slot time", HFILL }
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},
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{ &hf_ax25_kiss_txtail,
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{ "Tx tail", "ax25_kiss.txtail",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"Tx tail", HFILL }
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},
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{ &hf_ax25_kiss_fullduplex,
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{ "Full duplex", "ax25_kiss.fullduplex",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"Full duplex", HFILL }
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},
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{ &hf_ax25_kiss_sethardware,
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{ "Set hardware", "ax25_kiss.sethardware",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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"Set hardware", HFILL }
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},
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};
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/* Setup protocol subtree array */
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static gint *ett[] = {
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&ett_ax25_kiss,
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};
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/* Register the protocol name and description */
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proto_ax25_kiss = proto_register_protocol( "AX.25 KISS", "AX.25 KISS", "ax25_kiss" );
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/* Register the dissector */
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register_dissector( "ax25_kiss", dissect_ax25_kiss, proto_ax25_kiss );
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/* Required function calls to register the header fields and subtrees used */
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proto_register_field_array( proto_ax25_kiss, hf, array_length( hf ) );
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proto_register_subtree_array( ett, array_length( ett ) );
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/* Register preferences module */
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ax25_kiss_module = prefs_register_protocol( proto_ax25_kiss, proto_reg_handoff_ax25_kiss );
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/* Register any preference */
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/*
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prefs_register_bool_preference( ax25_kiss_module, "showhex",
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"Display numbers in Hex",
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"Enable to display numerical values in hexadecimal.",
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&gPREF_HEX );
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*/
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}
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void
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proto_reg_handoff_ax25_kiss(void)
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{
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static gboolean inited = FALSE;
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if( !inited ) {
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dissector_handle_t kiss_handle;
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kiss_handle = create_dissector_handle( dissect_ax25_kiss, proto_ax25_kiss );
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dissector_add( "wtap_encap", WTAP_ENCAP_AX25_KISS, kiss_handle );
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inited = TRUE;
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}
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}
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void
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capture_ax25_kiss( const guchar *pd, int offset, int len, packet_counts *ld)
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{
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int l_offset;
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guint8 kiss_cmd;
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if ( ! BYTES_ARE_IN_FRAME( offset, len, KISS_HEADER_SIZE ) ) {
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ld->other++;
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return;
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}
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l_offset = offset;
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kiss_cmd = pd[ l_offset ];
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l_offset += KISS_HEADER_SIZE; /* step over kiss header */
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switch ( kiss_cmd & KISS_CMD_MASK )
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{
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case KISS_DATA_FRAME : break;
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case KISS_TXDELAY : l_offset += 1; break;
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case KISS_PERSISTENCE : l_offset += 1; break;
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case KISS_SLOT_TIME : l_offset += 1; break;
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case KISS_TXTAIL : l_offset += 1; break;
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case KISS_FULLDUPLEX : l_offset += 1; break;
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case KISS_SETHARDWARE : l_offset += 1; break;
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case KISS_RETURN : break;
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default : break;
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}
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}
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