/* packet-qllc.c
 * Routines for QLLC protocol - Qualified? LLC
 * Gilbert Ramirez <gram@alumni.rice.edu>
 *
 * $Id: packet-qllc.c,v 1.8 2003/01/06 02:24:57 guy Exp $
 *
 * Ethereal - Network traffic analyzer
 * By Gerald Combs <gerald@ethereal.com>
 * Copyright 2001 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <glib.h>
#include <epan/packet.h>

static int proto_qllc = -1;
static int hf_qllc_address = -1;
static int hf_qllc_control = -1;

static gint ett_qllc = -1;

static dissector_handle_t sna_handle;

#define QSM                 0x93
#define QDISC               0x53
#define QXID                0xbf
#define QTEST               0xf3
#define QRR                 0xf1
#define QRD                 0x53
#define QUA                 0x73
#define QDM                 0x1f
#define QFRMR               0x97
#define QUI                 0x03
#define QUI_NO_REPLY        0x13
#define QSIM                0x17

#define QRD_QDISC_VALUE     0x53
#define QDISC_TEXT          "QDISC"
#define QRD_TEXT            "QRD"

/* Control Field */
static const value_string qllc_control_vals[] = {
    { QUI,          "QUI" },
    { QUI_NO_REPLY, "QUI - reply required" },
    { QSIM,         "QSIM" },
    { QDM,          "QDM" },
    { QUA,          "QUA" },
    { QSM,          "QSM" },
    { QFRMR,        "QFRMR" },
    { QXID,         "QXID" },
    { QRR,          "QRR" },
    { QTEST,        "QTEST" },
    { QDISC,        QDISC_TEXT },
    { QRD,          QRD_TEXT },
    { 0x00, NULL },
};


static void
dissect_qllc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
    proto_tree	*qllc_tree = NULL;
    proto_item	*qllc_ti = NULL;
    gboolean	*q_bit_set = pinfo->private_data;
    guint8	address, ctrl;
    gboolean	command = FALSE;

    /*
     * If the Q bit isn't set, this is just SNA data.
     */
    if (!(*q_bit_set)) {
	call_dissector(sna_handle, tvb, pinfo, tree);
	return;
    }

    /* Summary information */
    if (check_col(pinfo->cinfo, COL_PROTOCOL))
	col_set_str(pinfo->cinfo, COL_PROTOCOL, "QLLC");
    if (check_col(pinfo->cinfo, COL_INFO))
	col_clear(pinfo->cinfo, COL_INFO);

    if (tree) {
	qllc_ti = proto_tree_add_item(tree, proto_qllc, tvb, 0, -1, FALSE);
	qllc_tree = proto_item_add_subtree(qllc_ti, ett_qllc);
    }

    /* Get the address; we need it to determine if this is a
     * COMMAND or a RESPONSE */
    address = tvb_get_guint8(tvb, 0);
    if (tree) {
	proto_tree_add_item(qllc_tree, hf_qllc_address, tvb, 0, 1, FALSE);
    }

    /* The address field equals X'FF' in commands (except QRR)
     * and anything in responses. */
    ctrl = tvb_get_guint8(tvb, 1);
    if (ctrl != QRR && address == 0xff) {
        command = TRUE;
    }


    /* Disambiguate QRD_QDISC_VALUE, based on whether this packet is
     * a COMMAND or RESPONSE. */
    if (ctrl == QRD_QDISC_VALUE) {
        if (command) {
            if (check_col(pinfo->cinfo, COL_INFO)) {
                col_set_str(pinfo->cinfo, COL_INFO, QDISC_TEXT);
            }
            if (tree) {
                proto_tree_add_text(qllc_tree, tvb,
                        1, 1, "Control Field: %s (0x%02x)", QDISC_TEXT, ctrl);
            }
        }
        else {
            if (check_col(pinfo->cinfo, COL_INFO)) {
                col_set_str(pinfo->cinfo, COL_INFO, QRD_TEXT);
            }
            if (tree) {
                proto_tree_add_text(qllc_tree, tvb,
                        1, 1, "Control Field: %s (0x%02x)", QRD_TEXT, ctrl);
            }
        }

        /* Add the field for filtering purposes */
        if (tree) {
            proto_tree_add_uint_hidden(qllc_tree, hf_qllc_control, tvb,
                    1, 1, ctrl);
        }
    }
    else {
        /* Non-ambiguous control field value */
        if (check_col(pinfo->cinfo, COL_INFO)) {
            col_set_str(pinfo->cinfo, COL_INFO,
                    val_to_str(ctrl, qllc_control_vals,
                        "Control Field: 0x%02x (unknown)"));
        }
        if (tree) {
            proto_tree_add_uint(qllc_tree, hf_qllc_control, tvb,
                    1, 1, ctrl);
        }
    }

    /* Do we have an I field ? */
    /* XXX - I field exists for QUI too, but only for subarea nodes.
     * Need to test for this. */
    if (ctrl == QXID || ctrl == QTEST || ctrl == QFRMR) {
        /* yes */
    }
}

void
proto_register_qllc(void)
{
	static hf_register_info hf[] = {
	    { &hf_qllc_address,
		{ "Address Field",	"qllc.address", FT_UINT8, BASE_HEX, NULL, 0x0,
			"", HFILL }},

		{ &hf_qllc_control,
		{ "Control Field",	"qllc.control", FT_UINT8, BASE_HEX,
		  VALS(qllc_control_vals), 0x0, "", HFILL }},
	};

	static gint *ett[] = {
		&ett_qllc,
	};

	proto_qllc = proto_register_protocol("Qualified Logical Link Control",
            "QLLC", "qllc");
	proto_register_field_array(proto_qllc, hf, array_length(hf));
	proto_register_subtree_array(ett, array_length(ett));
	register_dissector("qllc", dissect_qllc, proto_qllc);
}

void
proto_reg_handoff_qllc(void)
{
	sna_handle = find_dissector("sna");
}