/* packet-pw-hdlc.c

 * Routines for HDLC PW dissection as per RFC4618.

 * Copyright 2009, Dmitry Trebich, Artem Tamazov <artem.tamazov@tellabs.com>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 *

 * History:

 * ---------------------------------

 * 02.03.2009 Initial implementation, supports:

 * - HDLC mode (rfc4618 5.1), no CW, payload is PPP (PPP in HDLC-like Framing (rfc1662)).

 * - FR port mode (rfc4618 5.2), no CW.

 *

 * [informative: Not supported yet:

 * - All kinds of HDLC PW with CW.

 * - PPP mode (rfc4618 5.3).

 * - For HDLC mode, decoding payloads other than PPP.]

 */

#include "config.h"

#include <epan/packet.h>

void proto_register_pw_hdlc(void);

void proto_reg_handoff_pw_hdlc(void);

static dissector_handle_t ppp_handle;

static dissector_handle_t fr_handle;

static dissector_handle_t pw_hdlc_nocw_fr_handle;

static dissector_handle_t pw_ppp_handle;

static int proto_pw_hdlc_nocw_fr;

static int proto_pw_hdlc_nocw_hdlc_ppp;

static int ett_pw_hdlc;

/* static int hf_pw_hdlc; */

static int hf_pw_hdlc_address_field;

static int hf_pw_hdlc_address;

static int hf_pw_hdlc_cr_bit;

static int hf_pw_hdlc_control_field;

static int hf_pw_hdlc_pf_bit;

static int hf_pw_hdlc_modifier;

static int hf_pw_hdlc_frame;

static const value_string pw_hdlc_modifier_vals[] = {

  {0x00, "UI - Unnumbered information" },

  {0x08, "UP - Unnumbered poll" },

  {0x10, "DISC/RD - Disconnect/Request disconnect" },

  {0x18, "UA - Unnumbered acknowledgment" },

  {0x20, "SNRM - Set normal response mode" },

  {0x38, "TEST - Test" },

  {0x01, "SIM/RIM - Set initialization mode/Request initialization mode" },

  {0x21, "FRMR - Frame reject" },

  {0x03, "SARM/DM - Set asynchronous response mode/Disconnect mode" },

  {0x0B, "SABM - Set asynchronous balanced mode" },

  {0x13, "SARME - Set asynchronous response extended mode" },

  {0x1B, "SABME - Set asynchronous balanced extended mode" },

  {0x23, "RSET - Reset" },

  {0x2B, "XID - Exchange identification" },

  {0x33, "SNRME - Set normal response extended mode" },

  {0, NULL }

};

static int dissect_pw_hdlc_nocw_fr( tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* data _U_ )

{

  return call_dissector( fr_handle, tvb, pinfo, tree );

}

static int dissect_pw_hdlc_nocw_hdlc_ppp( tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* data _U_ )

{

  if (tvb_reported_length_remaining(tvb, 0) < 2)

  {

    return 0;

  }

  if (tree)

  {

    proto_tree  *tr;

    proto_item  *item;

    proto_item  *item_address;

    proto_item  *item_control;

    uint8_t     addr;

    uint8_t     control;

    addr  = tvb_get_uint8(tvb, 0);

    control = tvb_get_uint8(tvb, 1);

    item = proto_tree_add_item( tree, proto_pw_hdlc_nocw_hdlc_ppp, tvb, 0, 2, ENC_NA );

    tr = proto_item_add_subtree( item, ett_pw_hdlc );

    item_address = proto_tree_add_item( tr, hf_pw_hdlc_address_field, tvb, 0, 1, ENC_BIG_ENDIAN );

    item_control = proto_tree_add_item( tr, hf_pw_hdlc_control_field, tvb, 1, 1, ENC_BIG_ENDIAN );

    tr = proto_item_add_subtree( item_address, ett_pw_hdlc );

    if ( 0x3F == (( addr & 0xFC ) >> 2 ))

      proto_tree_add_uint_format_value( tr, hf_pw_hdlc_address, tvb, 0, 1, 0xFC, "0x%x (All stations)", 0x3F );

    else

      proto_tree_add_uint( tr, hf_pw_hdlc_address, tvb, 0, 1, ( addr & 0xFC ) >> 2 );

    proto_tree_add_uint( tr, hf_pw_hdlc_cr_bit, tvb, 0, 1, ( addr & 2 ) >> 1 );

    tr = proto_item_add_subtree( item_control, ett_pw_hdlc );

    if ( control & 1 )

    {

      if ( control & 2 )

      {

        proto_tree_add_uint_format( tr, hf_pw_hdlc_frame, tvb, 1, 1, control, "U frame" );

        proto_tree_add_uint( tr, hf_pw_hdlc_pf_bit, tvb, 1, 1, ( control & 0x10 ) >> 4 );

        proto_tree_add_uint( tr, hf_pw_hdlc_modifier, tvb, 1, 1, (control & 0xEC) >> 2);

      }

      else

      {

        proto_tree_add_uint_format( tr, hf_pw_hdlc_frame, tvb, 1, 1, control, "S frame" );

      }

    }

    else

    {

      proto_tree_add_uint_format( tr, hf_pw_hdlc_frame, tvb, 1, 1, control, "I frame" );

    }

  }

  call_dissector( ppp_handle, tvb_new_subset_remaining(tvb, 2), pinfo, tree );

  return tvb_captured_length(tvb);

}

void proto_register_pw_hdlc(void)

{

  static hf_register_info hf[] = {

#if 0

    {

      &hf_pw_hdlc,

      {

        "PW HDLC", "pw_hdlc", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL

      }

    },

#endif

    {

      &hf_pw_hdlc_address_field,

      {

        "Address field", "pw_hdlc.address_field",

        FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL

      }

    },

    {

      &hf_pw_hdlc_address,

      {

        "Address", "pw_hdlc.address",

        FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL

      }

    },

    {

      &hf_pw_hdlc_cr_bit,

      {

        "C/R bit", "pw_hdlc.cr_bit",

        FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL

      }

    },

    {

      &hf_pw_hdlc_control_field,

      {

        "Control field", "pw_hdlc.control_field",

        FT_UINT8, BASE_HEX, NULL, 0x0, NULL, HFILL

      }

    },

    {

      &hf_pw_hdlc_pf_bit,

      {

        "Poll/Final bit", "pw_hdlc.pf_bit",

        FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL

      }

    },

    {

      &hf_pw_hdlc_modifier,

      {

        "Modifier", "pw_hdlc.modifier",

        FT_UINT8, BASE_HEX, VALS(pw_hdlc_modifier_vals), 0x0, NULL, HFILL

      }

    },

    {

      &hf_pw_hdlc_frame,

      {

        "Frame type", "pw_hdlc.frame",

        FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL

      }

    },

  };

  static int *ett[] = {

    &ett_pw_hdlc

  };

  proto_pw_hdlc_nocw_fr = proto_register_protocol("HDLC PW, FR port mode (no CW)", /*not displayed*/

              "HDLC PW, FR port mode (no CW)",

              "pw_hdlc_nocw_fr" );

  proto_pw_hdlc_nocw_hdlc_ppp = proto_register_protocol("HDLC-like framing for PPP",

                    "HDLC PW with PPP payload (no CW)",

                    "pw_hdlc_nocw_hdlc_ppp" );

  proto_register_field_array(proto_pw_hdlc_nocw_fr, hf, array_length(hf));

  proto_register_subtree_array(ett, array_length(ett));

  pw_hdlc_nocw_fr_handle = register_dissector("pw_hdlc_nocw_fr", dissect_pw_hdlc_nocw_fr, proto_pw_hdlc_nocw_fr );

  pw_ppp_handle = register_dissector("pw_hdlc_nocw_hdlc_ppp", dissect_pw_hdlc_nocw_hdlc_ppp, proto_pw_hdlc_nocw_hdlc_ppp );

}

void proto_reg_handoff_pw_hdlc(void)

{

  dissector_add_for_decode_as( "mpls.label", pw_hdlc_nocw_fr_handle );

  dissector_add_for_decode_as( "mpls.label", pw_ppp_handle );

  dissector_add_for_decode_as( "mpls.pfn", pw_hdlc_nocw_fr_handle );

  dissector_add_for_decode_as( "mpls.pfn", pw_ppp_handle );

  ppp_handle = find_dissector_add_dependency( "ppp", proto_pw_hdlc_nocw_hdlc_ppp );

  fr_handle = find_dissector_add_dependency( "fr", proto_pw_hdlc_nocw_fr );

}

/*

 * Editor modelines  -  https://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:

 */