/* packet-qllc.c

 * Routines for QLLC protocol - Qualified? LLC

 * Gilbert Ramirez <gram@alumni.rice.edu>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 2001 Gerald Combs

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 */

#include "config.h"

#include <epan/packet.h>

void proto_register_qllc(void);

void proto_reg_handoff_qllc(void);

static int proto_qllc;

static int hf_qllc_address;

static int hf_qllc_control;

static int ett_qllc;

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 / QRD" }, /* Same value for QDISC and QRD (following it is a COMMAND or RESPONSE) */

    { 0x00, NULL },

};

static int

dissect_qllc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)

{

    proto_tree *qllc_tree;

    proto_item *qllc_ti;

    bool       *q_bit_set;

    uint8_t     addr, ctrl;

    bool        command = false;

    /* Reject the packet if data is NULL */

    if (data == NULL)

        return 0;

    q_bit_set = (bool *)data;

    /*

     * If the Q bit isn't set, this is just SNA data.

     */

    if (!(*q_bit_set)) {

        call_dissector(sna_handle, tvb, pinfo, tree);

        return tvb_captured_length(tvb);

    }

    /* Summary information */

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "QLLC");

    col_clear(pinfo->cinfo, COL_INFO);

    qllc_ti = proto_tree_add_item(tree, proto_qllc, tvb, 0, -1, ENC_NA);

    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 */

    addr = tvb_get_uint8(tvb, 0);

    proto_tree_add_item(qllc_tree, hf_qllc_address, tvb, 0, 1, ENC_BIG_ENDIAN);

    /* The address field equals X'FF' in commands (except QRR)

     * and anything in responses. */

    ctrl = tvb_get_uint8(tvb, 1);

    if (ctrl != QRR && addr == 0xff) {

        command = true;

    }

    /* Disambiguate QRD_QDISC_VALUE, based on whether this packet is

     * a COMMAND or RESPONSE. */

    if (ctrl == QRD_QDISC_VALUE) {

        if (command) {

            col_set_str(pinfo->cinfo, COL_INFO, QDISC_TEXT);

            proto_tree_add_uint_format_value(qllc_tree, hf_qllc_control, tvb,

                    1, 1, ctrl, "%s (0x%02x)", QDISC_TEXT, ctrl);

        }

        else {

            col_set_str(pinfo->cinfo, COL_INFO, QRD_TEXT);

            proto_tree_add_uint_format_value(qllc_tree, hf_qllc_control, tvb,

                    1, 1, ctrl, "%s (0x%02x)", QRD_TEXT, ctrl);

        }

    }

    else {

        /* Non-ambiguous control field value */

        col_add_str(pinfo->cinfo, COL_INFO,

                    val_to_str(ctrl, qllc_control_vals,

                        "Control Field: 0x%02x (unknown)"));

        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 */

    }

    return tvb_captured_length(tvb);

}

void

proto_register_qllc(void)

{

    static hf_register_info hf[] = {

        { &hf_qllc_address,

          { "Address Field", "qllc.address", FT_UINT8, BASE_HEX, NULL, 0x0,

            NULL, HFILL }},

        { &hf_qllc_control,

          { "Control Field", "qllc.control", FT_UINT8, BASE_HEX,

            VALS(qllc_control_vals), 0x0, NULL, HFILL }},

    };

    static int *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_add_dependency("sna", proto_qllc);

}

/*

 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html

 *

 * Local variables:

 * c-basic-offset: 4

 * tab-width: 8

 * indent-tabs-mode: nil

 * End:

 *

 * vi: set shiftwidth=4 tabstop=8 expandtab:

 * :indentSize=4:tabSize=8:noTabs=true:

 */