/* packet-lmi.c
 * Routines for Frame Relay Local Management Interface (LMI) disassembly
 * Copyright 2001, Jeffrey C. Foster <jfoste@woodward.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * ToDo:
 *
 * References:
 *
 * http://www.techfest.com/networking/wan/frrel.htm
 * https://www.broadband-forum.org/technical/download/FRF.1.2/frf1_2.pdf
 * http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/frame.htm#xtocid18
 * http://www.net.aapt.com.au/techref/lmimess.htm
 * http://www.raleigh.ibm.com:80/cgi-bin/bookmgr/BOOKS/EZ305800/1.2.4.4
 */


#include "config.h"

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

void proto_register_lmi(void);
void proto_reg_handoff_lmi(void);

static dissector_handle_t lmi_handle;

static int proto_lmi;
static int hf_lmi_call_ref;
static int hf_lmi_msg_type;
static int hf_lmi_inf_ele;
static int hf_lmi_inf_len;

static int hf_lmi_rcd_type;
static int hf_lmi_send_seq;
static int hf_lmi_recv_seq;
static int hf_lmi_dlci_high;
static int hf_lmi_dlci_low;
static int hf_lmi_new;
static int hf_lmi_act;

static gint ett_lmi;
static gint ett_lmi_ele;

#ifdef _OLD_
/*
 * Bits in the address field.
 */
#define LMI_CMD 0xf000    /* LMI Command */
#define LMI_SEQ 0x0fff    /* LMI Sequence number */

#endif

static const value_string msg_type_str[] = {
    {0x75, "Status Enquiry"},
    {0x7D, "Status"},
    { 0,   NULL }
};

static const value_string element_type_str[] = {

    /*** These are the ANSI values ***/
    {0x01, "Report"},
    {0x03, "Keep Alive"},
    {0x07, "PVC Status"},

    /*** These are the ITU values ***/
    {0x51, "Report"},
    {0x53, "Keep Alive"},
    {0x07, "PVC Status"},

    {0,       NULL }
};

static const value_string record_type_str[] = {
    {0x00, "Full Status"},
    {0x01, "Link Integrity Verification Only"},
    {0x02, "Single PVC"},
    {0,    NULL }
};

static const value_string pvc_status_new_str[] = {
    {0x00, "PVC already present"},
    {0x01, "PVC is new"},
    {0,    NULL }
};

static const value_string pvc_status_act_str[] = {
    {0x00, "PVC is Inactive"},
    {0x01, "PVC is Active"},
    {0,    NULL }
};

static void
dissect_lmi_report_type(tvbuff_t *tvb, int offset, proto_tree *tree)
{
    proto_tree_add_item(tree, hf_lmi_rcd_type, tvb, offset, 1, ENC_NA);
}

static void
dissect_lmi_link_int(tvbuff_t *tvb, int offset, proto_tree *tree)
{
    proto_tree_add_item(tree, hf_lmi_send_seq, tvb, offset, 1, ENC_NA);
    ++offset;
    proto_tree_add_item(tree, hf_lmi_recv_seq, tvb, offset, 1, ENC_NA);

}

static void
dissect_lmi_pvc_status(tvbuff_t *tvb, int offset, proto_tree *tree)
{
    proto_tree_add_item(tree, hf_lmi_dlci_high, tvb, offset, 1, ENC_NA);
    ++offset;
    proto_tree_add_item(tree, hf_lmi_dlci_low, tvb, offset, 1, ENC_NA);
    ++offset;
    proto_tree_add_item(tree, hf_lmi_new, tvb, offset, 1, ENC_NA);
    proto_tree_add_item(tree, hf_lmi_act, tvb, offset, 1, ENC_NA);
}

static int
dissect_lmi(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    proto_tree    *lmi_tree, *lmi_subtree;
    proto_item    *ti;
    int           offset = 2, len;
    guint8        msg_type;
    guint8        ele_id;

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "LMI");
    col_clear(pinfo->cinfo, COL_INFO);

    ti = proto_tree_add_item(tree, proto_lmi, tvb, 0, 3, ENC_NA);
    lmi_tree = proto_item_add_subtree(ti, ett_lmi_ele);

    proto_tree_add_item(lmi_tree, hf_lmi_call_ref, tvb, 0, 1, ENC_BIG_ENDIAN);

    msg_type = tvb_get_guint8( tvb, 1);
    col_add_str(pinfo->cinfo, COL_INFO,
            val_to_str(msg_type, msg_type_str, "Unknown message type (0x%02x)"));

    proto_tree_add_uint(lmi_tree, hf_lmi_msg_type, tvb, 1, 1, msg_type);

    /* Display the LMI elements */
    while (tvb_reported_length_remaining(tvb, offset) > 0) {
        ele_id = tvb_get_guint8( tvb, offset);
        len =  tvb_get_guint8( tvb, offset + 1);

        lmi_subtree = proto_tree_add_subtree_format(lmi_tree, tvb, offset, len + 2,
                ett_lmi_ele, NULL, "Information Element: %s",
                val_to_str(ele_id, element_type_str, "Unknown (%u)"));

        proto_tree_add_uint(lmi_subtree, hf_lmi_inf_ele, tvb, offset, 1,
                ele_id);
        ++offset;
        proto_tree_add_uint(lmi_subtree, hf_lmi_inf_len, tvb, offset, 1, len);
        ++offset;
        if (( ele_id == 1) || (ele_id == 51))
            dissect_lmi_report_type( tvb, offset, lmi_subtree);
        else if (( ele_id == 3) || (ele_id == 53))
            dissect_lmi_link_int( tvb, offset, lmi_subtree);
        else if (( ele_id == 7) || (ele_id == 57))
            dissect_lmi_pvc_status( tvb, offset, lmi_subtree);
        offset += len;
    }
    return tvb_captured_length(tvb);
}


void
proto_register_lmi(void)
{
    static hf_register_info hf[] = {
        { &hf_lmi_call_ref,
            { "Call reference", "lmi.cmd", FT_UINT8, BASE_HEX, NULL, 0,
                NULL, HFILL }},

        { &hf_lmi_msg_type,
            { "Message Type", "lmi.msg_type", FT_UINT8, BASE_HEX, VALS(msg_type_str), 0,
                NULL, HFILL }},

        { &hf_lmi_inf_ele,
            { "Type", "lmi.inf_ele_type", FT_UINT8, BASE_DEC, VALS(element_type_str), 0,
                "Information Element Type", HFILL }},
        { &hf_lmi_inf_len,
            { "Length", "lmi.inf_ele_len", FT_UINT8, BASE_DEC, NULL, 0,
                "Information Element Length", HFILL }},

        { &hf_lmi_rcd_type,
            { "Record Type", "lmi.ele_rcd_type", FT_UINT8, BASE_DEC, VALS(record_type_str), 0,
                NULL, HFILL }},
        { &hf_lmi_send_seq,
            { "Send Seq", "lmi.send_seq", FT_UINT8, BASE_DEC, NULL, 0,
                "Send Sequence", HFILL }},
        { &hf_lmi_recv_seq,
            { "Recv Seq", "lmi.recv_seq", FT_UINT8, BASE_DEC, NULL, 0,
                "Receive Sequence", HFILL }},
        { &hf_lmi_dlci_high,
            { "DLCI High", "lmi.dlci_hi", FT_UINT8, BASE_DEC, NULL, 0x3f,
                "DLCI High bits", HFILL }},
        { &hf_lmi_dlci_low,
            { "DLCI Low", "lmi.dlci_low", FT_UINT8, BASE_DEC, NULL, 0x78,
                "DLCI Low bits", HFILL }},
        { &hf_lmi_new,
            { "DLCI New", "lmi.dlci_new", FT_UINT8, BASE_DEC, VALS(pvc_status_new_str), 0x08,
                "DLCI New Flag", HFILL }},
        { &hf_lmi_act,
            { "DLCI Active","lmi.dlci_act", FT_UINT8, BASE_DEC, VALS(pvc_status_act_str), 0x02,
                "DLCI Active Flag", HFILL }},
    };
    static gint *ett[] = {
        &ett_lmi,
        &ett_lmi_ele,
    };
    proto_lmi = proto_register_protocol ("Local Management Interface", "LMI", "lmi");
    proto_register_field_array (proto_lmi, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));

    lmi_handle = register_dissector("lmi", dissect_lmi, proto_lmi);
}

void
proto_reg_handoff_lmi(void)
{
    dissector_add_uint("fr.nlpid", NLPID_LMI, lmi_handle);
}


/*
 * 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:
 */