/* packet-sscop.c
 * Routines for SSCOP (Q.2110, Q.SAAL) frame disassembly
 * Guy Harris <guy@alum.mit.edu>
 *
 * $Id: packet-sscop.c 35224 2010-12-20 05:35:29Z guy $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998
 *
 *
 * 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 <glib.h>
#include <epan/packet.h>
#include <prefs.h>
#include "packet-sscop.h"

int proto_sscop = -1;

static int hf_sscop_type = -1;
static int hf_sscop_sq = -1;
static int hf_sscop_mr = -1;
static int hf_sscop_s = -1;
static int hf_sscop_ps = -1;
static int hf_sscop_r = -1;
static int hf_sscop_stat_s = -1;
static int hf_sscop_stat_count = -1;

static gint ett_sscop = -1;
static gint ett_stat = -1;

static dissector_handle_t q2931_handle;
static dissector_handle_t data_handle;
static dissector_handle_t sscf_nni_handle;
static dissector_handle_t alcap_handle;
static dissector_handle_t nbap_handle;

static module_t *sscop_module;

static range_t *global_udp_port_range;

static dissector_handle_t sscop_handle;


static enum_val_t sscop_payload_dissector_options[] = {
  { "data",	"Data (no further dissection)",	DATA_DISSECTOR },
  { "Q.2931",	"Q.2931",	Q2931_DISSECTOR },
  { "SSCF-NNI",	"SSCF-NNI (MTP3-b)",		SSCF_NNI_DISSECTOR },
  { "ALCAP",	"ALCAP",			ALCAP_DISSECTOR },
  { "NBAP",	"NBAP",				NBAP_DISSECTOR },
  { NULL,	NULL,				0 }
};

static guint sscop_payload_dissector = Q2931_DISSECTOR;
static dissector_handle_t default_handle;

static sscop_info_t sscop_info;
/*
 * See
 *
 *	http://www.protocols.com/pbook/atmsig.htm
 *
 * for some information on SSCOP, although, alas, not the actual PDU
 * type values - those I got from the FreeBSD 3.2 ATM code.
 */

/*
 * SSCOP PDU types.
 */
#define	SSCOP_TYPE_MASK	0x0f

#define	SSCOP_BGN	0x01	/* Begin */
#define	SSCOP_BGAK	0x02	/* Begin Acknowledge */
#define	SSCOP_BGREJ	0x07	/* Begin Reject */
#define	SSCOP_END	0x03	/* End */
#define	SSCOP_ENDAK	0x04	/* End Acknowledge */
#define	SSCOP_RS	0x05	/* Resynchronization */
#define	SSCOP_RSAK	0x06	/* Resynchronization Acknowledge */
#define	SSCOP_SD	0x08	/* Sequenced Data */
#define	SSCOP_SDP	0x09	/* Sequenced Data with Poll */
#define	SSCOP_POLL	0x0a	/* Status Request */
#define	SSCOP_STAT	0x0b	/* Solicited Status Response */
#define	SSCOP_USTAT	0x0c	/* Unsolicited Status Response */
#define	SSCOP_UD	0x0d	/* Unnumbered Data */
#define	SSCOP_MD	0x0e	/* Management Data */
#define	SSCOP_ER	0x09	/* Error Recovery */
#define	SSCOP_ERAK	0x0f	/* Error Acknowledge */

#define	SSCOP_S		0x10	/* Source bit in End PDU */

/*
 * XXX - how to distinguish SDP from ER?
 */
static const value_string sscop_type_vals[] = {
	{ SSCOP_BGN,   "Begin" },
	{ SSCOP_BGAK,  "Begin Acknowledge" },
	{ SSCOP_BGREJ, "Begin Reject" },
	{ SSCOP_END,   "End" },
	{ SSCOP_ENDAK, "End Acknowledge" },
	{ SSCOP_RS,    "Resynchronization" },
	{ SSCOP_RSAK,  "Resynchronization Acknowledge" },
	{ SSCOP_SD,    "Sequenced Data" },
#if 0
	{ SSCOP_SDP,   "Sequenced Data with Poll" },
#endif
	{ SSCOP_POLL,  "Status Request" },
	{ SSCOP_STAT,  "Solicited Status Response" },
	{ SSCOP_USTAT, "Unsolicited Status Response" },
	{ SSCOP_UD,    "Unnumbered Data" },
	{ SSCOP_MD,    "Management Data" },
	{ SSCOP_ER,    "Error Recovery" },
	{ SSCOP_ERAK,  "Error Acknowledge" },
	{ 0,            NULL }
};

/*
 * The SSCOP "header" is a trailer, so the "offsets" are computed based
 * on the length of the packet.
 */

/*
 * PDU type.
 */
#define	SSCOP_PDU_TYPE	(reported_length - 4)	/* single byte */

/*
 * Begin PDU, Begin Acknowledge PDU (no N(SQ) in it), Resynchronization
 * PDU, Resynchronization Acknowledge PDU (no N(SQ) in it in Q.SAAL),
 * Error Recovery PDU, Error Recovery Acknoledge PDU (no N(SQ) in it).
 */
#define	SSCOP_N_SQ	(reported_length - 5)	/* One byte */
#define	SSCOP_N_MR	(reported_length - 4)	/* lower 3 bytes thereof */

/*
 * Sequenced Data PDU (no N(PS) in it), Sequenced Data with Poll PDU,
 * Poll PDU.
 */
#define	SSCOP_N_PS	(reported_length - 8)	/* lower 3 bytes thereof */
#define	SSCOP_N_S	(reported_length - 4)	/* lower 3 bytes thereof */

/*
 * Solicited Status PDU, Unsolicited Status PDU (no N(PS) in it).
 */
#define	SSCOP_SS_N_PS	(reported_length - 12)	/* lower 3 bytes thereof */
#define	SSCOP_SS_N_MR	(reported_length - 8)	/* lower 3 bytes thereof */
#define	SSCOP_SS_N_R	(reported_length - 4)	/* lower 3 bytes thereof */

static void dissect_stat_list(proto_tree *tree, tvbuff_t *tvb,guint h) {
	gint n,i;
	proto_item* pi;

	if ((n = (tvb_reported_length(tvb))/4 - h)) {
		pi = proto_tree_add_text(tree,tvb,0,n*4,"SD List");
		tree = proto_item_add_subtree(pi,ett_stat);

		for (i = 0; i < n; i++) {
			proto_tree_add_item(tree, hf_sscop_stat_s, tvb, i*4 + 1,3,FALSE);
		}
	}
}

extern void
dissect_sscop_and_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, dissector_handle_t payload_handle)
{
  guint reported_length;
  proto_item *ti;
  proto_tree *sscop_tree = NULL;
  guint8 sscop_pdu_type;
  int pdu_len;
  int pad_len;
  tvbuff_t *next_tvb;

  reported_length = tvb_reported_length(tvb);	/* frame length */
  sscop_pdu_type = tvb_get_guint8(tvb, SSCOP_PDU_TYPE);
  sscop_info.type = sscop_pdu_type & SSCOP_TYPE_MASK;

  col_set_str(pinfo->cinfo, COL_PROTOCOL, "SSCOP");
  if (check_col(pinfo->cinfo, COL_INFO))
    col_add_str(pinfo->cinfo, COL_INFO, val_to_str(sscop_info.type, sscop_type_vals,
					"Unknown PDU type (0x%02x)"));

  /*
   * Find the length of the PDU and, if there's any payload and
   * padding, the length of the padding.
   */
  switch (sscop_info.type) {

  case SSCOP_SD:
    pad_len = (sscop_pdu_type >> 6) & 0x03;
    pdu_len = 4;
    break;

  case SSCOP_BGN:
  case SSCOP_BGAK:
  case SSCOP_BGREJ:
  case SSCOP_END:
  case SSCOP_RS:
#if 0
  case SSCOP_SDP:
#endif
    pad_len = (sscop_pdu_type >> 6) & 0x03;
    sscop_info.payload_len = pdu_len = 8;
    break;

  case SSCOP_UD:
    pad_len = (sscop_pdu_type >> 6) & 0x03;
    sscop_info.payload_len = pdu_len = 4;
    break;

  default:
    pad_len = 0;
    pdu_len = reported_length;	/* No payload, just SSCOP */
	sscop_info.payload_len = 0;
    break;
  }

  if (tree) {
    ti = proto_tree_add_protocol_format(tree, proto_sscop, tvb,
					reported_length - pdu_len,
    					pdu_len, "SSCOP");
    sscop_tree = proto_item_add_subtree(ti, ett_sscop);

    proto_tree_add_item(sscop_tree, hf_sscop_type, tvb, SSCOP_PDU_TYPE, 1,FALSE);

    switch (sscop_info.type) {

    case SSCOP_BGN:
    case SSCOP_RS:
    case SSCOP_ER:
      proto_tree_add_item(sscop_tree, hf_sscop_sq, tvb, SSCOP_N_SQ, 1,FALSE);
      proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, FALSE);
      break;

    case SSCOP_END:
      proto_tree_add_text(sscop_tree, tvb, SSCOP_PDU_TYPE, 1,
          "Source: %s", (sscop_pdu_type & SSCOP_S) ? "SSCOP" : "User");
      break;

    case SSCOP_BGAK:
    case SSCOP_RSAK:
		proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, FALSE);
      break;

    case SSCOP_ERAK:
		proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_N_MR + 1, 3, FALSE);
      break;

    case SSCOP_SD:
		proto_tree_add_item(sscop_tree, hf_sscop_s, tvb, SSCOP_N_S + 1, 3, FALSE);
      break;

#if 0
    case SSCOP_SDP:
#endif
    case SSCOP_POLL:
      proto_tree_add_item(sscop_tree, hf_sscop_ps, tvb, SSCOP_N_PS + 1, 3,FALSE);
	  proto_tree_add_item(sscop_tree, hf_sscop_s, tvb, SSCOP_N_S + 1, 3,FALSE);
      break;

    case SSCOP_STAT:
		proto_tree_add_item(sscop_tree, hf_sscop_ps, tvb, SSCOP_SS_N_PS + 1, 3,FALSE);
		proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_SS_N_MR + 1, 3, FALSE);
		proto_tree_add_item(sscop_tree, hf_sscop_r, tvb, SSCOP_SS_N_R + 1, 3,FALSE);
		dissect_stat_list(sscop_tree,tvb,3);
      break;

    case SSCOP_USTAT:
		proto_tree_add_item(sscop_tree, hf_sscop_mr, tvb, SSCOP_SS_N_MR + 1, 3, FALSE);
		proto_tree_add_item(sscop_tree, hf_sscop_r, tvb, SSCOP_SS_N_R + 1, 3,FALSE);
		dissect_stat_list(sscop_tree,tvb,2);
      break;
    }
  }

  /*
   * Dissect the payload, if any.
   *
   * XXX - what about a Management Data PDU?
   */
  switch (sscop_info.type) {

  case SSCOP_SD:
  case SSCOP_UD:
  case SSCOP_BGN:
  case SSCOP_BGAK:
  case SSCOP_BGREJ:
  case SSCOP_END:
  case SSCOP_RS:
#if 0
  case SSCOP_SDP:
#endif
    if (tree) {
      proto_tree_add_text(sscop_tree, tvb, SSCOP_PDU_TYPE, 1,
			"Pad length: %u", pad_len);
    }

    /*
     * Compute length of data in PDU - subtract the trailer length
     * and the pad length from the reported length.
     */
    reported_length -= (pdu_len + pad_len);

    if (reported_length != 0) {
      /*
       * We know that we have all of the payload, because we know we have
       * at least 4 bytes of data after the payload, i.e. the SSCOP trailer.
       * Therefore, we know that the captured length of the payload is
       * equal to the length of the payload.
       */
      next_tvb = tvb_new_subset(tvb, 0, reported_length, reported_length);
      if (sscop_info.type == SSCOP_SD)
      {
		  call_dissector(payload_handle, next_tvb, pinfo, tree);
      }
    break;
  }
}
}

static void dissect_sscop(tvbuff_t* tvb, packet_info* pinfo,proto_tree* tree)
{
    struct _sscop_payload_info  *p_sscop_info;
    dissector_handle_t subdissector;

	/* Look for packet info for subdissector information */
    p_sscop_info = p_get_proto_data(pinfo->fd, proto_sscop);

	if ( p_sscop_info
		 && ( subdissector = p_sscop_info->subdissector )
		 && ( subdissector == data_handle
			  || subdissector == q2931_handle
			  || subdissector == sscf_nni_handle
			  || subdissector == alcap_handle
			  || subdissector == nbap_handle) )
		dissect_sscop_and_payload(tvb,pinfo,tree,subdissector);
    else
		dissect_sscop_and_payload(tvb,pinfo,tree,default_handle);
}


static void range_delete_callback(guint32 port)
{
    if (port) {
	dissector_delete_uint("udp.port", port, sscop_handle);
    }
}

static void range_add_callback(guint32 port)
{
    if (port) {
	dissector_add_uint("udp.port", port, sscop_handle);
    }
}

/* Make sure handles for various protocols are initialized */
static void initialize_handles_once(void) {
    static gboolean initialized = FALSE;
    if (!initialized) {
		sscop_handle = create_dissector_handle(dissect_sscop, proto_sscop);

		q2931_handle = find_dissector("q2931");
		data_handle = find_dissector("data");
		sscf_nni_handle = find_dissector("sscf-nni");
		alcap_handle = find_dissector("alcap");
		nbap_handle = find_dissector("nbap");

		initialized = TRUE;
    }
}

gboolean sscop_allowed_subdissector(dissector_handle_t handle)
{
    initialize_handles_once();
    if (handle == q2931_handle || handle == data_handle
	|| handle == sscf_nni_handle || handle == alcap_handle
	|| handle == nbap_handle)
	return TRUE;
    return FALSE;
}

void
proto_reg_handoff_sscop(void)
{
  static gboolean prefs_initialized = FALSE;
  static range_t *udp_port_range;

  if (!prefs_initialized) {
    initialize_handles_once();
    prefs_initialized = TRUE;

  } else {

    range_foreach(udp_port_range, range_delete_callback);
    g_free(udp_port_range);

  }

  udp_port_range = range_copy(global_udp_port_range);

  range_foreach(udp_port_range, range_add_callback);

  switch(sscop_payload_dissector) {
	  case DATA_DISSECTOR: default_handle = data_handle; break;
	  case Q2931_DISSECTOR: default_handle = q2931_handle; break;
	  case SSCF_NNI_DISSECTOR: default_handle = sscf_nni_handle; break;
	  case ALCAP_DISSECTOR: default_handle = alcap_handle; break;
	  case NBAP_DISSECTOR: default_handle = nbap_handle; break;
	}

}

void
proto_register_sscop(void)
{
	static hf_register_info hf[] = {
		{ &hf_sscop_type, { "PDU Type", "sscop.type", FT_UINT8, BASE_HEX,	VALS(sscop_type_vals), SSCOP_TYPE_MASK, NULL, HFILL }},
		{ &hf_sscop_sq, { "N(SQ)", "sscop.sq", FT_UINT8, BASE_DEC,	NULL, 0x0, NULL, HFILL }},
		{ &hf_sscop_mr, { "N(MR)", "sscop.mr", FT_UINT24, BASE_DEC,	NULL, 0x0, NULL, HFILL }},
		{ &hf_sscop_s, { "N(S)", "sscop.s", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
		{ &hf_sscop_ps, { "N(PS)", "sscop.ps", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
		{ &hf_sscop_r, { "N(R)", "sscop.r", FT_UINT24, BASE_DEC, NULL, 0x0, NULL, HFILL }},
		{ &hf_sscop_stat_s, { "N(S)", "sscop.stat.s", FT_UINT24, BASE_DEC, NULL, 0x0,NULL, HFILL }},
		{ &hf_sscop_stat_count, { "Number of NACKed pdus", "sscop.stat.count", FT_UINT32, BASE_DEC, NULL, 0x0,NULL, HFILL }}
	};

  static gint *ett[] = {
    &ett_sscop,
	&ett_stat
  };

  proto_sscop = proto_register_protocol("SSCOP", "SSCOP", "sscop");
  proto_register_field_array(proto_sscop, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));
  register_dissector("sscop", dissect_sscop, proto_sscop);

  sscop_module = prefs_register_protocol(proto_sscop, proto_reg_handoff_sscop);

  global_udp_port_range = range_empty();

  prefs_register_range_preference(sscop_module, "udp.ports",
				 "SSCOP UDP port range",
				 "Set the UDP port for SSCOP messages encapsulated in UDP (0 to disable)",
				 &global_udp_port_range, MAX_UDP_PORT);

  prefs_register_enum_preference(sscop_module, "payload",
				 "SSCOP payload protocol",
				 "SSCOP payload (dissector to call on SSCOP payload)",
				 (gint *)&sscop_payload_dissector,
				 sscop_payload_dissector_options, FALSE);
}

