wireshark/epan/dissectors/packet-clnp.c

/* packet-clnp.c
 * Routines for ISO/OSI network protocol packet disassembly
 *
 * $Id$
 * Laurent Deniel <laurent.deniel@free.fr>
 * Ralf Schneider <Ralf.Schneider@t-online.de>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 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 <stdio.h>
#include <string.h>
#include <ctype.h>
#include <glib.h>
#include <epan/prefs.h>
#include <epan/packet.h>
#include <epan/reassemble.h>
#include "packet-frame.h"
#include "packet-osi.h"
#include "packet-osi-options.h"
#include "packet-isis.h"
#include "packet-esis.h"
#include <epan/nlpid.h>
#include <epan/ipproto.h>
#include <epan/expert.h>
#include <epan/strutil.h>

/* protocols and fields */

static int  proto_clnp         = -1;
static gint ett_clnp           = -1;
static gint ett_clnp_type      = -1;
static gint ett_clnp_segments  = -1;
static gint ett_clnp_segment   = -1;
static gint ett_clnp_disc_pdu  = -1;

static int hf_clnp_id          = -1;
static int hf_clnp_length      = -1;
static int hf_clnp_version     = -1;
static int hf_clnp_ttl         = -1;
static int hf_clnp_type        = -1;
static int hf_clnp_pdu_length  = -1;
static int hf_clnp_checksum    = -1;
static int hf_clnp_dest_length = -1;
static int hf_clnp_dest        = -1;
static int hf_clnp_src_length  = -1;
static int hf_clnp_src         = -1;
static int hf_clnp_segments    = -1;
static int hf_clnp_segment     = -1;
static int hf_clnp_segment_overlap = -1;
static int hf_clnp_segment_overlap_conflict = -1;
static int hf_clnp_segment_multiple_tails = -1;
static int hf_clnp_segment_too_long_segment = -1;
static int hf_clnp_segment_error = -1;
static int hf_clnp_reassembled_in = -1;

static const fragment_items clnp_frag_items = {
	&ett_clnp_segment,
	&ett_clnp_segments,
	&hf_clnp_segments,
	&hf_clnp_segment,
	&hf_clnp_segment_overlap,
	&hf_clnp_segment_overlap_conflict,
	&hf_clnp_segment_multiple_tails,
	&hf_clnp_segment_too_long_segment,
	&hf_clnp_segment_error,
	&hf_clnp_reassembled_in,
	"segments"
};

static dissector_handle_t clnp_handle;
static dissector_handle_t ositp_handle;
static dissector_handle_t ositp_inactive_handle;
static dissector_handle_t data_handle;

/*
 * ISO 8473 OSI CLNP definition (see RFC994)
 *
 *            _________________________________
 *           |           Fixed Part            |
 *           |_________________________________|
 *           |          Address Part           |
 *           |_________________________________|
 *           |   Segmentation Part (optional)  |
 *           |_________________________________|
 *           |     Options Part (optional)     |
 *           |_________________________________|
 *           |         Data (optional)         |
 *           |_________________________________|
 */

#define	ISO8473_V1  0x01    /* CLNP version 1 */

/* Fixed part */

#define CNF_TYPE		0x1f
#define CNF_ERR_OK		0x20
#define CNF_MORE_SEGS		0x40
#define CNF_SEG_OK		0x80

#define DT_NPDU			0x1C
#define MD_NPDU			0x1D
#define ER_NPDU			0x01
#define ERQ_NPDU		0x1E
#define ERP_NPDU		0x1F

static const value_string npdu_type_abbrev_vals[] = {
  { DT_NPDU,	"DT" },
  { MD_NPDU,	"MD" },
  { ER_NPDU,	"ER" },
  { ERQ_NPDU,	"ERQ" },
  { ERP_NPDU,	"ERP" },
  { 0,		NULL }
};

static const value_string npdu_type_vals[] = {
  { DT_NPDU,	"Data" },
  { MD_NPDU,	"Multicast Data" },
  { ER_NPDU,	"Error Report" },
  { ERQ_NPDU,	"Echo Request" },
  { ERP_NPDU,	"Echo Response" },
  { 0,		NULL }
};

/* field position */

#define P_CLNP_PROTO_ID		0
#define P_CLNP_HDR_LEN		1
#define P_CLNP_VERS		2
#define P_CLNP_TTL		3
#define P_CLNP_TYPE		4
#define P_CLNP_SEGLEN		5
#define P_CLNP_CKSUM		7
#define P_CLNP_ADDRESS_PART	9

/* Segmentation part */

struct clnp_segment {
  gushort	cng_id;		/* data unit identifier */
  gushort	cng_off;	/* segment offset */
  gushort	cng_tot_len;	/* total length */
};

/* NSAP selector */

#define NSEL_NET 		0x00
#define NSEL_NP  		0x20
#define NSEL_TP  		0x21

/* global variables */

/* List of dissectors to call for CLNP packets */
static heur_dissector_list_t clnp_heur_subdissector_list;

/*
 * Reassembly of CLNP.
 */
static GHashTable *clnp_segment_table = NULL;
static GHashTable *clnp_reassembled_table = NULL;

/* options */
static guint tp_nsap_selector = NSEL_TP;
static gboolean always_decode_transport = FALSE;
static gboolean clnp_reassemble = TRUE;

/* function definitions */

/*
 *  CLNP part / main entry point
*/

static void dissect_clnp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
  proto_tree *clnp_tree = NULL;
  proto_item *ti;
  guint8      cnf_proto_id;
  guint8      cnf_hdr_len;
  guint8      cnf_vers;
  guint8      cnf_ttl;
  guint8      cnf_type;
  char        flag_string[6+1];
  const char *pdu_type_string;
  proto_tree *type_tree;
  guint16     segment_length;
  guint16     du_id = 0;
  guint16     segment_offset = 0;
  guint16     cnf_cksum;
  cksum_status_t cksum_status;
  int         offset;
  guchar      src_len, dst_len, nsel, opt_len = 0;
  const guint8     *dst_addr, *src_addr;
  gint        len;
  guint       next_length;
  proto_tree *discpdu_tree;
  gboolean    save_in_error_pkt;
  fragment_data *fd_head;
  tvbuff_t   *next_tvb;
  gboolean    update_col_info = TRUE;
  gboolean    save_fragmented;

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

  cnf_proto_id = tvb_get_guint8(tvb, P_CLNP_PROTO_ID);
  if (cnf_proto_id == NLPID_NULL) {
    col_set_str(pinfo->cinfo, COL_INFO, "Inactive subset");
    if (tree) {
      ti = proto_tree_add_item(tree, proto_clnp, tvb, P_CLNP_PROTO_ID, 1, FALSE);
      clnp_tree = proto_item_add_subtree(ti, ett_clnp);
      proto_tree_add_uint_format(clnp_tree, hf_clnp_id, tvb, P_CLNP_PROTO_ID, 1,
				 cnf_proto_id,
				 "Inactive subset");
    }
    next_tvb = tvb_new_subset_remaining(tvb, 1);
    if (call_dissector(ositp_inactive_handle, next_tvb, pinfo, tree) == 0)
      call_dissector(data_handle,tvb, pinfo, tree);
    return;
  }

  /* return if version not known */
  cnf_vers = tvb_get_guint8(tvb, P_CLNP_VERS);
  if (cnf_vers != ISO8473_V1) {
    call_dissector(data_handle,tvb, pinfo, tree);
    return;
  }

  /* fixed part decoding */
  cnf_hdr_len = tvb_get_guint8(tvb, P_CLNP_HDR_LEN);
  opt_len = cnf_hdr_len;

  if (tree) {
    ti = proto_tree_add_item(tree, proto_clnp, tvb, 0, cnf_hdr_len, FALSE);
    clnp_tree = proto_item_add_subtree(ti, ett_clnp);
    proto_tree_add_uint(clnp_tree, hf_clnp_id, tvb, P_CLNP_PROTO_ID, 1,
			       cnf_proto_id);
    proto_tree_add_uint(clnp_tree, hf_clnp_length, tvb, P_CLNP_HDR_LEN, 1,
			cnf_hdr_len);
    proto_tree_add_uint(clnp_tree, hf_clnp_version, tvb, P_CLNP_VERS, 1,
			cnf_vers);
    cnf_ttl = tvb_get_guint8(tvb, P_CLNP_TTL);
    proto_tree_add_uint_format(clnp_tree, hf_clnp_ttl, tvb, P_CLNP_TTL, 1,
			       cnf_ttl,
			       "Holding Time : %u (%u.%u secs)",
			       cnf_ttl, cnf_ttl / 2, (cnf_ttl % 2) * 5);
  }

  cnf_type = tvb_get_guint8(tvb, P_CLNP_TYPE);
  pdu_type_string = val_to_str(cnf_type & CNF_TYPE, npdu_type_abbrev_vals,
				"Unknown (0x%02x)");
  flag_string[0] = '\0';
  if (cnf_type & CNF_SEG_OK)
    g_strlcat(flag_string, "S ", 7);
  if (cnf_type & CNF_MORE_SEGS)
    g_strlcat(flag_string, "M ", 7);
  if (cnf_type & CNF_ERR_OK)
    g_strlcat(flag_string, "E ", 7);
  if (tree) {
    ti = proto_tree_add_uint_format(clnp_tree, hf_clnp_type, tvb, P_CLNP_TYPE, 1,
			       cnf_type,
			       "PDU Type     : 0x%02x (%s%s)",
			       cnf_type,
			       flag_string,
			       pdu_type_string);
    type_tree = proto_item_add_subtree(ti, ett_clnp_type);
    proto_tree_add_text(type_tree, tvb, P_CLNP_TYPE, 1, "%s",
			decode_boolean_bitfield(cnf_type, CNF_SEG_OK, 8,
				      "Segmentation permitted",
				      "Segmentation not permitted"));
    proto_tree_add_text(type_tree, tvb, P_CLNP_TYPE, 1, "%s",
			decode_boolean_bitfield(cnf_type, CNF_MORE_SEGS, 8,
				      "More segments",
				      "Last segment"));
    proto_tree_add_text(type_tree, tvb, P_CLNP_TYPE, 1, "%s",
			decode_boolean_bitfield(cnf_type, CNF_ERR_OK, 8,
				      "Report error if PDU discarded",
				      "Don't report error if PDU discarded"));
    proto_tree_add_text(type_tree, tvb, P_CLNP_TYPE, 1, "%s",
			decode_enumerated_bitfield(cnf_type, CNF_TYPE, 8,
				      npdu_type_vals, "%s"));
  }

  /* If we don't have the full header - i.e., not enough to see the
     segmentation part and determine whether this datagram is segmented
     or not - set the Info column now; we'll get an exception before
     we set it otherwise. */

  if (tvb_length(tvb) < cnf_hdr_len) {
    if (check_col(pinfo->cinfo, COL_INFO))
      col_add_fstr(pinfo->cinfo, COL_INFO, "%s NPDU %s", pdu_type_string, flag_string);
  }

  segment_length = tvb_get_ntohs(tvb, P_CLNP_SEGLEN);
  cnf_cksum = tvb_get_ntohs(tvb, P_CLNP_CKSUM);
  cksum_status = calc_checksum(tvb, 0, cnf_hdr_len, cnf_cksum);
  if (tree) {
    proto_tree_add_uint(clnp_tree, hf_clnp_pdu_length, tvb, P_CLNP_SEGLEN, 2,
			segment_length);
    switch (cksum_status) {

    default:
	/*
	 * No checksum present, or not enough of the header present to
	 * checksum it.
	 */
	proto_tree_add_uint_format(clnp_tree, hf_clnp_checksum, tvb,
			       P_CLNP_CKSUM, 2,
			       cnf_cksum,
			       "Checksum     : 0x%04x",
			       cnf_cksum);
	break;

    case CKSUM_OK:
	/*
	 * Checksum is correct.
	 */
	proto_tree_add_uint_format(clnp_tree, hf_clnp_checksum, tvb,
			       P_CLNP_CKSUM, 2,
			       cnf_cksum,
			       "Checksum     : 0x%04x (correct)",
			       cnf_cksum);
	break;

    case CKSUM_NOT_OK:
	/*
	 * Checksum is not correct.
	 */
	proto_tree_add_uint_format(clnp_tree, hf_clnp_checksum, tvb,
			       P_CLNP_CKSUM, 2,
			       cnf_cksum,
			       "Checksum     : 0x%04x (incorrect)",
			       cnf_cksum);
	break;
    }
    opt_len -= 9; /* Fixed part of Hesder */
  } /* tree */

  /* address part */

  offset = P_CLNP_ADDRESS_PART;
  dst_len  = tvb_get_guint8(tvb, offset);
  dst_addr = tvb_get_ptr(tvb, offset + 1, dst_len);
  nsel     = tvb_get_guint8(tvb, offset + dst_len);
  src_len  = tvb_get_guint8(tvb, offset + dst_len + 1);
  src_addr = tvb_get_ptr(tvb, offset + dst_len + 2, src_len);

  if (tree) {
    proto_tree_add_uint(clnp_tree, hf_clnp_dest_length, tvb, offset, 1,
			dst_len);
    proto_tree_add_bytes_format(clnp_tree, hf_clnp_dest, tvb, offset + 1 , dst_len,
			       dst_addr,
			       " DA : %s",
			       print_nsap_net(dst_addr, dst_len));
    proto_tree_add_uint(clnp_tree, hf_clnp_src_length, tvb,
			offset + 1 + dst_len, 1, src_len);
    proto_tree_add_bytes_format(clnp_tree, hf_clnp_src, tvb,
			       offset + dst_len + 2, src_len,
			       src_addr,
			       " SA : %s",
			       print_nsap_net(src_addr, src_len));

    opt_len -= dst_len + src_len +2;
  }

  SET_ADDRESS(&pinfo->net_src, AT_OSI, src_len, src_addr);
  SET_ADDRESS(&pinfo->src, AT_OSI, src_len, src_addr);
  SET_ADDRESS(&pinfo->net_dst, AT_OSI, dst_len, dst_addr);
  SET_ADDRESS(&pinfo->dst, AT_OSI, dst_len, dst_addr);

  /* Segmentation Part */

  offset += dst_len + src_len + 2;

  if (cnf_type & CNF_SEG_OK) {
    struct clnp_segment seg;			/* XXX - not used */
    tvb_memcpy(tvb, (guint8 *)&seg, offset, sizeof(seg));	/* XXX - not used */

    segment_offset = tvb_get_ntohs(tvb, offset + 2);
    du_id = tvb_get_ntohs(tvb, offset);
    if (tree) {
      proto_tree_add_text(clnp_tree, tvb, offset, 2,
			"Data unit identifier: %06u",
			du_id);
      proto_tree_add_text(clnp_tree, tvb, offset + 2 , 2,
			"Segment offset      : %6u",
			segment_offset);
      proto_tree_add_text(clnp_tree, tvb, offset + 4 , 2,
			"Total length        : %6u",
			tvb_get_ntohs(tvb, offset + 4));
    }

    offset  += 6;
    opt_len -= 6;
  }

  if (tree) {
    /* To do : decode options  */
/*
    proto_tree_add_text(clnp_tree, tvb, offset,
			cnf_hdr_len - offset,
			"Options/Data: <not shown>");
*/
/* QUICK HACK Option Len:= PDU_Hd_length-( FixedPart+AddresPart+SegmentPart )*/

    dissect_osi_options( opt_len,
                         tvb, offset, clnp_tree );
  }

  /* Length of CLNP datagram plus headers above it. */
  len = segment_length;

  offset = cnf_hdr_len;

  /* If clnp_reassemble is on, this is a segment, we have all the
   * data in the segment, and the checksum is valid, then just add the
   * segment to the hashtable.
   */
  save_fragmented = pinfo->fragmented;
  if (clnp_reassemble && (cnf_type & CNF_SEG_OK) &&
	((cnf_type & CNF_MORE_SEGS) || segment_offset != 0) &&
	tvb_bytes_exist(tvb, offset, segment_length - cnf_hdr_len) &&
	segment_length > cnf_hdr_len &&
	cksum_status != CKSUM_NOT_OK) {
    fd_head = fragment_add_check(tvb, offset, pinfo, du_id, clnp_segment_table,
			   clnp_reassembled_table, segment_offset,
			   segment_length - cnf_hdr_len,
			   cnf_type & CNF_MORE_SEGS);

    next_tvb = process_reassembled_data(tvb, offset, pinfo, "Reassembled CLNP",
        fd_head, &clnp_frag_items, &update_col_info, clnp_tree);
  } else {
    /* If this is the first segment, dissect its contents, otherwise
       just show it as a segment.

       XXX - if we eventually don't save the reassembled contents of all
       segmented datagrams, we may want to always reassemble. */
    if ((cnf_type & CNF_SEG_OK) && segment_offset != 0) {
      /* Not the first segment - don't dissect it. */
      next_tvb = NULL;
    } else {
      /* First segment, or not segmented.  Dissect what we have here. */

      /* Get a tvbuff for the payload. */
      next_tvb = tvb_new_subset_remaining(tvb, offset);

      /*
       * If this is the first segment, but not the only segment,
       * tell the next protocol that.
       */
      if ((cnf_type & (CNF_SEG_OK|CNF_MORE_SEGS)) == (CNF_SEG_OK|CNF_MORE_SEGS))
        pinfo->fragmented = TRUE;
      else
        pinfo->fragmented = FALSE;
    }
  }

  if (next_tvb == NULL) {
    /* Just show this as a segment. */
    if (check_col(pinfo->cinfo, COL_INFO))
      col_add_fstr(pinfo->cinfo, COL_INFO, "Fragmented %s NPDU %s(off=%u)",
		pdu_type_string, flag_string, segment_offset);

    /* As we haven't reassembled anything, we haven't changed "pi", so
       we don't have to restore it. */
    call_dissector(data_handle, tvb_new_subset_remaining(tvb, offset), pinfo,
                   tree);
    pinfo->fragmented = save_fragmented;
    return;
  }

  if (tvb_offset_exists(tvb, offset)) {
    switch (cnf_type & CNF_TYPE) {

    case DT_NPDU:
    case MD_NPDU:
      /* Continue with COTP if any data.
         XXX - if this isn't the first Derived PDU of a segmented Initial
         PDU, skip that? */

      if (nsel == (char)tp_nsap_selector || always_decode_transport) {
        if (call_dissector(ositp_handle, next_tvb, pinfo, tree) != 0) {
          pinfo->fragmented = save_fragmented;
          return;	/* yes, it appears to be COTP or CLTP */
        }
      }
      if (dissector_try_heuristic(clnp_heur_subdissector_list, next_tvb,
				  pinfo, tree))	{
          pinfo->fragmented = save_fragmented;
          return;	/* yes, it appears to be one of the protocols in the heuristic list */
      }

      break;

    case ER_NPDU:
      /* The payload is the header and "none, some, or all of the data
         part of the discarded PDU", i.e. it's like an ICMP error;
	 dissect it as a CLNP PDU. */
      if (check_col(pinfo->cinfo, COL_INFO))
        col_add_fstr(pinfo->cinfo, COL_INFO, "%s NPDU %s", pdu_type_string, flag_string);
      if (tree) {
        next_length = tvb_length_remaining(tvb, offset);
        if (next_length != 0) {
          /* We have payload; dissect it. */
          ti = proto_tree_add_text(clnp_tree, tvb, offset, next_length,
            "Discarded PDU");
          discpdu_tree = proto_item_add_subtree(ti, ett_clnp_disc_pdu);

          /* Save the current value of the "we're inside an error packet"
             flag, and set that flag; subdissectors may treat packets
             that are the payload of error packets differently from
             "real" packets. */
          save_in_error_pkt = pinfo->in_error_pkt;
          pinfo->in_error_pkt = TRUE;

          call_dissector(clnp_handle, next_tvb, pinfo, discpdu_tree);

          /* Restore the "we're inside an error packet" flag. */
          pinfo->in_error_pkt = save_in_error_pkt;
        }
      }
      pinfo->fragmented = save_fragmented;
      return;	/* we're done with this PDU */

    case ERQ_NPDU:
    case ERP_NPDU:
      /* XXX - dissect this */
      break;
    }
  }
  if (check_col(pinfo->cinfo, COL_INFO))
    col_add_fstr(pinfo->cinfo, COL_INFO, "%s NPDU %s", pdu_type_string, flag_string);
  call_dissector(data_handle,next_tvb, pinfo, tree);
  pinfo->fragmented = save_fragmented;
} /* dissect_clnp */

static void
clnp_reassemble_init(void)
{
  fragment_table_init(&clnp_segment_table);
  reassembled_table_init(&clnp_reassembled_table);
}

void proto_register_clnp(void)
{
  static hf_register_info hf[] = {
    { &hf_clnp_id,
      { "Network Layer Protocol Identifier", "clnp.nlpi", FT_UINT8, BASE_HEX,
        VALS(nlpid_vals), 0x0, NULL, HFILL }},

    { &hf_clnp_length,
      { "HDR Length", "clnp.len",	   FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_version,
      { "Version", "clnp.version",  FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_ttl,
      { "Holding Time", "clnp.ttl",	   FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_type,
      { "PDU Type", "clnp.type",     FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_pdu_length,
      { "PDU length", "clnp.pdu.len",  FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_checksum,
      { "Checksum", "clnp.checksum", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_dest_length,
      { "DAL", "clnp.dsap.len", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_dest,
      { "DA", "clnp.dsap",     FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_src_length,
      { "SAL", "clnp.ssap.len", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_src,
      { "SA", "clnp.ssap",     FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL }},

    { &hf_clnp_segment_overlap,
      { "Segment overlap", "clnp.segment.overlap", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
	"Segment overlaps with other segments", HFILL }},

    { &hf_clnp_segment_overlap_conflict,
      { "Conflicting data in segment overlap", "clnp.segment.overlap.conflict", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
	"Overlapping segments contained conflicting data", HFILL }},

    { &hf_clnp_segment_multiple_tails,
      { "Multiple tail segments found", "clnp.segment.multipletails", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
	"Several tails were found when reassembling the packet", HFILL }},

    { &hf_clnp_segment_too_long_segment,
      { "Segment too long", "clnp.segment.toolongsegment", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
	"Segment contained data past end of packet", HFILL }},

    { &hf_clnp_segment_error,
      { "Reassembly error", "clnp.segment.error", FT_FRAMENUM, BASE_NONE, NULL, 0x0,
	"Reassembly error due to illegal segments", HFILL }},

    { &hf_clnp_segment,
      { "CLNP Segment", "clnp.segment", FT_FRAMENUM, BASE_NONE, NULL, 0x0,
	NULL, HFILL }},

    { &hf_clnp_segments,
      { "CLNP Segments", "clnp.segments", FT_NONE, BASE_NONE, NULL, 0x0,
	NULL, HFILL }},

    { &hf_clnp_reassembled_in,
      { "Reassembled CLNP in frame", "clnp.reassembled_in", FT_FRAMENUM, BASE_NONE, NULL, 0x0,
	"This CLNP packet is reassembled in this frame", HFILL }}
  };
  static gint *ett[] = {
    &ett_clnp,
    &ett_clnp_type,
    &ett_clnp_segments,
    &ett_clnp_segment,
    &ett_clnp_disc_pdu,
  };

  module_t *clnp_module;

  proto_clnp = proto_register_protocol(PROTO_STRING_CLNP, "CLNP", "clnp");
  proto_register_field_array(proto_clnp, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));
  register_dissector("clnp", dissect_clnp, proto_clnp);
  register_heur_dissector_list("clnp", &clnp_heur_subdissector_list);
  register_init_routine(clnp_reassemble_init);

  clnp_module = prefs_register_protocol(proto_clnp, NULL);
  prefs_register_uint_preference(clnp_module, "tp_nsap_selector",
	"NSAP selector for Transport Protocol (last byte in hex)",
	"NSAP selector for Transport Protocol (last byte in hex)",
       	16, &tp_nsap_selector);
  prefs_register_bool_preference(clnp_module, "always_decode_transport",
	"Always try to decode NSDU as transport PDUs",
	"Always try to decode NSDU as transport PDUs",
       	&always_decode_transport);
  prefs_register_bool_preference(clnp_module, "reassemble",
	"Reassemble segmented CLNP datagrams",
	"Whether segmented CLNP datagrams should be reassembled",
	&clnp_reassemble);
}

void
proto_reg_handoff_clnp(void)
{
  ositp_handle = find_dissector("ositp");
  ositp_inactive_handle = find_dissector("ositp_inactive");
  data_handle = find_dissector("data");

  clnp_handle = create_dissector_handle(dissect_clnp, proto_clnp);
  dissector_add("osinl", NLPID_ISO8473_CLNP, clnp_handle);
  dissector_add("osinl", NLPID_NULL, clnp_handle); /* Inactive subset */
  dissector_add("x.25.spi", NLPID_ISO8473_CLNP, clnp_handle);
}