/* packet-esis.c

 * Routines for ISO/OSI End System to Intermediate System

 * Routing Exchange Protocol ISO 9542.

 *

 * Ralf Schneider <Ralf.Schneider@t-online.de>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

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

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/expert.h>

#include <epan/unit_strings.h>

#include "packet-osi.h"

#include "packet-osi-options.h"

/* The version we support is 1 */

#define ESIS_REQUIRED_VERSION    1

/* ESIS PDU types */

#define ESIS_ESH_PDU    02

#define ESIS_ISH_PDU    04

#define ESIS_RD_PDU     06

/* The length of the fixed part */

#define ESIS_HDR_FIXED_LENGTH 9

void proto_register_esis(void);

void proto_reg_handoff_esis(void);

/* esis base header */

static int  proto_esis;

static int  hf_esis_nlpi;

static int  hf_esis_length;

static int  hf_esis_version;

static int  hf_esis_reserved;

static int  hf_esis_type;

static int  hf_esis_holdtime;

static int  hf_esis_checksum;

static int  hf_esis_checksum_status;

/* Generated from convert_proto_tree_add_text.pl */

static int hf_esis_dal;

static int hf_esis_number_of_source_addresses;

static int hf_esis_netl;

static int hf_esis_sal;

static int hf_esis_sa;

static int hf_esis_bsnpal;

static int hf_esis_net;

static int hf_esis_da;

static int hf_esis_bsnpa;

static int ett_esis;

static int ett_esis_area_addr;

static int ett_esis_network;

static int ett_esis_dest_addr;

static int ett_esis_subnetwork;

static expert_field ei_esis_version;

static expert_field ei_esis_length;

static expert_field ei_esis_type;

static expert_field ei_esis_checksum;

static dissector_handle_t esis_handle;

static const value_string esis_vals[] = {

  { ESIS_ESH_PDU, "ES HELLO"},

  { ESIS_ISH_PDU, "IS HELLO"},

  { ESIS_RD_PDU,  "RD REQUEST"},

  { 0,             NULL} };

/* ################## Descriptions ###########################################*/

/* Parameters for the ESH PDU

 * Source Address Parameter:

 *

 * Octet:    Length:   Parameter Type:

 *     10          1   Number of Source Addresses ( NSAPs served by this Network

 *     11          1   Source Address Length Indicator ( SAL )     #    Entity )

 * 12-m-1   variable   Source Address ( NSAP )

 *      m              Options, dissected in osi.c

 *

 *

 * Parameter for the ISH PDU:

 * Network Entity Title Parameter:

 *

 * Octet:    Length:   Parameter Type:

 *     10          1   Network Entity Title Length Indicator ( NETL )

 * 11-m-1   variable   Network Entity Title ( NET )

 *      m              Options, dissected in osi.c

 *

 *

 * Parameter for the RD PDU:

 * When re-directed to an IS:

 *

 *  Octet:   Length:   Parameter Type:

 *      10         1   Destination Address Length Indicator ( DAL )

 *  11>m-1  variable   Destination Address ( DA )

 *       m         1   Subnetwork Address Length Indicator ( BSNPAL )

 * m+1>n-1  variable   Subnetwork Address ( BSNPA )

 *       n         1   Network Entity Title Length Indicator ( NETL )

 * n+1>p-1  variable   Network Entity Title ( NET )

 *       p             Options, dissected in osi.c

 *

 *

 * Parameter for the RD PDU:

 * When re-directed to an ES:

 *

 *  Octet:   Length:   Parameter Type:

 *      10         1   Destination Address Length Indicator ( DAL )

 *  11>m-1  variable   Destination Address ( DA )

 *       m         1   Subnetwork Address Length Indicator ( BSNPAL )

 * m+1>n-1  variable   Subnetwork Address ( BSNPA )

 *       n         1   Network Entity Title Length Indicator ( NETL ) == 0

 *     n+1             Options, dissected in osi.c

 *

 */

/* ############################ Tool Functions ############################## */

static void

esis_dissect_esh_pdu( uint8_t len, tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo) {

    proto_tree *esis_area_tree;

    int         offset  = 0;

    unsigned    no_sa, sal;

    proto_item  *ti;

    offset += ESIS_HDR_FIXED_LENGTH;

    ti = proto_tree_add_item_ret_uint( tree, hf_esis_number_of_source_addresses, tvb, offset, 1, ENC_NA, &no_sa);

    len--;

    offset++;

    esis_area_tree = proto_item_add_subtree( ti, ett_esis_area_addr );

    while ( no_sa-- > 0 ) {

      proto_tree_add_item_ret_uint(esis_area_tree, hf_esis_sal, tvb, offset, 1, ENC_NA, &sal);

      offset++;

      proto_tree_add_string(esis_area_tree, hf_esis_sa, tvb, offset, sal, print_nsap_net( pinfo->pool, tvb, offset, sal ) );

      offset += sal;

      len    -= ( sal + 1 );

    }

    dissect_osi_options( len, tvb, offset, tree, pinfo );

} /* esis_dissect_esh_pdu */

static void

esis_dissect_ish_pdu( uint8_t len, tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo) {

    int   offset  = 0;

    int   netl    = 0;

    proto_tree* network_tree;

    offset += ESIS_HDR_FIXED_LENGTH;

    netl = (int) tvb_get_uint8(tvb, offset);

    network_tree = proto_tree_add_subtree( tree, tvb, offset, netl + 1, ett_esis_network, NULL,

                         "### Network Entity Title Section ###");

    proto_tree_add_uint(network_tree, hf_esis_netl, tvb, offset++, 1, netl);

    proto_tree_add_string(network_tree, hf_esis_net, tvb, offset, netl, print_nsap_net( pinfo->pool, tvb, offset, netl ) );

    offset += netl;

    len    -= ( netl + 1 );

    dissect_osi_options( len, tvb, offset, network_tree, pinfo );

}

static void

esis_dissect_redirect_pdu( uint8_t len, tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo) {

    int   offset  = 0;

    int   tmpl    = 0;

    proto_tree *dest_tree, *subnet_tree, *network_tree;

    offset += ESIS_HDR_FIXED_LENGTH;

    tmpl = (int) tvb_get_uint8(tvb, offset);

    dest_tree = proto_tree_add_subtree( tree, tvb, offset, tmpl + 1, ett_esis_dest_addr, NULL,

                         "### Destination Address Section ###" );

    proto_tree_add_uint(dest_tree, hf_esis_dal, tvb, offset++, 1, tmpl);

    proto_tree_add_string( dest_tree, hf_esis_da, tvb, offset, tmpl,

                         print_nsap_net( pinfo->pool, tvb, offset, tmpl ) );

    offset += tmpl;

    len    -= ( tmpl + 1 );

    tmpl    = (int) tvb_get_uint8(tvb, offset);

    subnet_tree = proto_tree_add_subtree( tree, tvb, offset, tmpl + 1, ett_esis_subnetwork, NULL,

                         "###  Subnetwork Address Section ###");

    proto_tree_add_uint(subnet_tree, hf_esis_bsnpal, tvb, offset++, 1, tmpl);

    proto_tree_add_item(subnet_tree, hf_esis_bsnpa, tvb, offset, tmpl, ENC_NA);

    offset += tmpl;

    len    -= ( tmpl + 1 );

    tmpl    = (int) tvb_get_uint8(tvb, offset);

    if ( 0 == tmpl ) {

      network_tree = proto_tree_add_subtree( tree, tvb, offset, 1, ett_esis_network, NULL,

                           "### No Network Entity Title Section ###" );

      offset++;

      len--;

    }

    else {

      network_tree = proto_tree_add_subtree( tree, tvb, offset, 1, ett_esis_network, NULL,

                           "### Network Entity Title Section ###" );

      proto_tree_add_uint(network_tree, hf_esis_netl, tvb, offset++, 1, tmpl);

      proto_tree_add_string( network_tree, hf_esis_net, tvb, offset, tmpl,

                           print_nsap_net( pinfo->pool, tvb, offset, tmpl ) );

      offset += tmpl;

      len    -= ( tmpl + 1 );

    }

    dissect_osi_options( len, tvb, offset, network_tree, pinfo );

}

/*

 * Name: dissect_esis()

 *

 * Description:

 *   Main entry area for esis de-mangling.  This will build the

 *   main esis tree data and call the sub-protocols as needed.

 *

 * Input:

 *   tvbuff *      : tvbuff referring to packet data

 *   packet_info * : info for current packet

 *   proto_tree *  : tree of display data.  May be NULL.

 *

 * Output:

 *   void, but we will add to the proto_tree if it is not NULL.

 */

static int

dissect_esis(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) {

  uint8_t version, length;

  proto_item *ti, *type_item;

  proto_tree *esis_tree    = NULL;

  uint8_t     variable_len, type;

  uint16_t    checksum;

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

  col_clear(pinfo->cinfo, COL_INFO);

    ti = proto_tree_add_item(tree, proto_esis, tvb, 0, -1, ENC_NA);

    esis_tree = proto_item_add_subtree(ti, ett_esis);

    proto_tree_add_item( esis_tree, hf_esis_nlpi, tvb, 0, 1, ENC_BIG_ENDIAN);

    ti = proto_tree_add_item( esis_tree, hf_esis_length, tvb, 1, 1, ENC_BIG_ENDIAN );

    length = tvb_get_uint8(tvb, 1);

    if (length < ESIS_HDR_FIXED_LENGTH) {

      expert_add_info_format(pinfo, ti, &ei_esis_length,

                           "Bogus ESIS length (%u, must be >= %u)",

                           length, ESIS_HDR_FIXED_LENGTH );

    }

    version = tvb_get_uint8(tvb, 2);

    ti = proto_tree_add_item( esis_tree, hf_esis_version, tvb, 2, 1, ENC_BIG_ENDIAN);

    if (version != ESIS_REQUIRED_VERSION){

      expert_add_info_format(pinfo, ti, &ei_esis_version,

                           "Unknown ESIS version (%u vs %u)",

                           version, ESIS_REQUIRED_VERSION );

    }

    proto_tree_add_item( esis_tree, hf_esis_reserved, tvb, 3, 1, ENC_BIG_ENDIAN);

    type_item = proto_tree_add_item( esis_tree, hf_esis_type, tvb, 4, 1, ENC_BIG_ENDIAN);

    type = tvb_get_uint8(tvb, 4) & OSI_PDU_TYPE_MASK;

    proto_tree_add_item(esis_tree, hf_esis_holdtime, tvb, 5, 2, ENC_BIG_ENDIAN);

    checksum = tvb_get_ntohs(tvb, 7);

    if (checksum == 0) {

        /* No checksum present */

        proto_tree_add_checksum(esis_tree, tvb, 7, hf_esis_checksum, -1, NULL, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NOT_PRESENT);

    } else {

        uint32_t c0 = 0, c1 = 0;

        if (osi_calc_checksum(tvb, 0, length, &c0, &c1)) {

            /* Successfully processed checksum, verify it */

            proto_tree_add_checksum(esis_tree, tvb, 7, hf_esis_checksum, hf_esis_checksum_status, &ei_esis_checksum, pinfo, c0 | c1, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_ZERO);

        } else {

            proto_tree_add_checksum(esis_tree, tvb, 7, hf_esis_checksum, hf_esis_checksum_status, &ei_esis_checksum, pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);

        }

    }

  /*

   * Let us make sure we use the same names for all our decodes

   * here.  First, dump the name into info column, and THEN

   * dispatch the sub-type.

   */

  col_add_str(pinfo->cinfo, COL_INFO,

                val_to_str(pinfo->pool, type, esis_vals,

                            "Unknown (0x%x)" ) );

  variable_len = length - ESIS_HDR_FIXED_LENGTH;

  switch (type) {

  case ESIS_ESH_PDU:

    esis_dissect_esh_pdu( variable_len, tvb, esis_tree, pinfo);

    break;

  case ESIS_ISH_PDU:

    esis_dissect_ish_pdu( variable_len, tvb, esis_tree, pinfo);

    break;

  case ESIS_RD_PDU:

    esis_dissect_redirect_pdu( variable_len, tvb, esis_tree, pinfo);

    break;

  default:

    expert_add_info(pinfo, type_item, &ei_esis_type);

  }

  return tvb_captured_length(tvb);

} /* dissect_esis */

/*

 * Name: proto_register_esis()

 *

 * Description:

 *      main register for esis protocol set.  We register some display

 *      formats and the protocol module variables.

 *

 *      NOTE: this procedure to autolinked by the makefile process that

 *      builds register.c

 *

 * Input:

 *      void

 *

 * Output:

 *      void

 */

void

proto_register_esis(void) {

  static hf_register_info hf[] = {

    { &hf_esis_nlpi,

      { "Network Layer Protocol Identifier", "esis.nlpi",

        FT_UINT8, BASE_HEX, VALS(nlpid_vals), 0x0, NULL, HFILL }},

    { &hf_esis_length,

      { "PDU Length", "esis.length",  FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_esis_version,

      { "Version", "esis.ver",  FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_esis_reserved,

      { "Reserved(==0)", "esis.res",  FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_esis_type,

      { "PDU Type", "esis.type",      FT_UINT8, BASE_DEC, VALS(esis_vals), OSI_PDU_TYPE_MASK, NULL, HFILL }},

    { &hf_esis_holdtime,

      { "Holding Time", "esis.htime", FT_UINT16, BASE_DEC|BASE_UNIT_STRING, UNS(&units_second_seconds), 0x0, NULL, HFILL }},

    { &hf_esis_checksum,

      { "Checksum", "esis.chksum",    FT_UINT16, BASE_HEX, NULL, 0x0, NULL, HFILL }},

    { &hf_esis_checksum_status,

      { "Checksum Status", "esis.chksum.status",    FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0, NULL, HFILL }},

      /* Generated from convert_proto_tree_add_text.pl */

      { &hf_esis_number_of_source_addresses, { "Number of Source Addresses (SA, Format: NSAP)", "esis.number_of_source_addresses", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

      { &hf_esis_sal, { "SAL", "esis.sal", FT_UINT8, BASE_DEC|BASE_UNIT_STRING, UNS(&units_octet_octets), 0x0, NULL, HFILL }},

      { &hf_esis_sa, { "SA", "esis.sa", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }},

      { &hf_esis_netl, { "NETL", "esis.netl", FT_UINT8, BASE_DEC|BASE_UNIT_STRING, UNS(&units_octet_octets), 0x0, NULL, HFILL }},

      { &hf_esis_dal, { "DAL", "esis.dal", FT_UINT8, BASE_DEC|BASE_UNIT_STRING, UNS(&units_octet_octets), 0x0, NULL, HFILL }},

      { &hf_esis_bsnpal, { "BSNPAL", "esis.bsnpal", FT_UINT8, BASE_DEC|BASE_UNIT_STRING, UNS(&units_octet_octets), 0x0, NULL, HFILL }},

      { &hf_esis_net, { "NET", "esis.net", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }},

      { &hf_esis_da, { "DA", "esis.da", FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL }},

      { &hf_esis_bsnpa, { "BSNPA", "esis.bsnpa", FT_SYSTEM_ID, BASE_NONE, NULL, 0x0, NULL, HFILL }},

  };

  static int *ett[] = {

    &ett_esis,

    &ett_esis_area_addr,

    &ett_esis_network,

    &ett_esis_dest_addr,

    &ett_esis_subnetwork

  };

  static ei_register_info ei[] = {

    { &ei_esis_version, { "esis.ver.unknown", PI_PROTOCOL, PI_WARN, "Unknown ESIS version", EXPFILL }},

    { &ei_esis_length, { "esis.length.invalid", PI_MALFORMED, PI_ERROR, "Bogus ESIS length", EXPFILL }},

    { &ei_esis_type, { "esis.type.unknown", PI_PROTOCOL, PI_WARN, "Unknown ESIS packet type", EXPFILL }},

    { &ei_esis_checksum, { "esis.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},

  };

  expert_module_t* expert_esis;

  proto_esis = proto_register_protocol( PROTO_STRING_ESIS, "ESIS", "esis");

  proto_register_field_array(proto_esis, hf, array_length(hf));

  proto_register_subtree_array(ett, array_length(ett));

  expert_esis = expert_register_protocol(proto_esis);

  expert_register_field_array(expert_esis, ei, array_length(ei));

  esis_handle = register_dissector("esis", dissect_esis, proto_esis);

}

void

proto_reg_handoff_esis(void)

{

  dissector_add_uint("osinl.incl", NLPID_ISO9542_ESIS, esis_handle);

}

/*

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

 *

 * Local Variables:

 * c-basic-offset: 2

 * tab-width: 8

 * indent-tabs-mode: nil

 * End:

 *

 * ex: set shiftwidth=2 tabstop=8 expandtab:

 * :indentSize=2:tabSize=8:noTabs=true:

 */