From Michael Lum:

	GSM A facility element decoding;

	make TCAP dissector export routines for use by various GSM
	dissectors;

	make GSM MAP dissector use exported TCAP routines/defines;

	GSM Supplementary Services support.

svn path=/trunk/; revision=10409

1 files changed, 810 insertions, 0 deletions

diff --git a/packet-gsm_ss.c b/packet-gsm_ss.c
new file mode 100644
index 0000000000..59e544ecec
--- /dev/null
+++ b/packet-gsm_ss.c
@@ -0,0 +1,810 @@
+/* packet-gsm_ss.c
+ * Routines for GSM Supplementary Services dissection
+ *
+ * NOTE:
+ *	Routines are shared by GSM MAP/GSM A dissectors.
+ *	This file provides SHARED routines and is NOT a
+ *	standalone dissector.
+ *
+ * Copyright 2004, Michael Lum <mlum [AT] telostech.com>
+ * In association with Telos Technology Inc.
+ *
+ * Title		3GPP			Other
+ *
+ *   Reference [1]
+ *   Mobile radio Layer 3 supplementary service specification;
+ *   Formats and coding
+ *   (3GPP TS 24.080 version 4.3.0 Release 4)
+ *
+ * Michael Lum <mlum [AT] telostech.com>,
+ * Created (2004).
+ *
+ * $Id: packet-gsm_ss.c,v 1.1 2004/03/19 07:54:57 guy Exp $
+ *
+ * Ethereal - Network traffic analyzer
+ * By Gerald Combs <gerald@ethereal.com>
+ * Copyright 1998 Gerald Combs
+ *
+ * Copied from packet-gsm_map.c (where "WHATEVER_FILE_YOU_USED"
+ * is a dissector file; if you just copied this from README.developer,
+ * don't bother with the "Copied from" - you don't even need to put
+ * in a "Copied from" if you copied an existing dissector, especially
+ * if the bulk of the code in the new dissector is your code)
+ *
+ * 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 <stdlib.h>
+#include <string.h>
+
+#include "epan/packet.h"
+#include "tap.h"
+#include "asn1.h"
+
+#include "packet-tcap.h"
+#include "packet-gsm_ss.h"
+
+
+const value_string gsm_ss_opr_code_strings[] = {
+    { 10,	"RegisterSS" },
+    { 11,	"EraseSS" },
+    { 12,	"ActivateSS" },
+    { 13,	"DeactivateSS" },
+    { 14,	"InterrogateSS" },
+    { 16,	"NotifySS" },
+    { 17,	"RegisterPassword" },
+    { 18,	"GetPassword" },
+    { 19,	"ProcessUnstructuredSS-Data" },
+    { 38,	"ForwardCheckSS-Indication" },
+    { 59,	"ProcessUnstructuredSS-Request" },
+    { 60,	"UnstructuredSS-Request" },
+    { 61,	"UnstructuredSS-Notify" },
+    { 77,	"EraseCC-Entry" },
+    { 119,	"AccessRegisterCCEntry" },
+    { 120,	"ForwardCUG-Info" },
+    { 121,	"SplitMPTY" },
+    { 122,	"RetrieveMPTY" },
+    { 123,	"HoldMPTY" },
+    { 124,	"BuildMPTY" },
+    { 125,	"ForwardChargeAdvice" },
+    { 126,	"ExplicitCT" },
+    { 0, NULL }
+};
+
+
+/* never initialize in field array */
+static int hf_null = -1;
+#define	HF_NULL		&hf_null
+
+gint gsm_ss_ett_sequence = -1;
+gint gsm_ss_ett_param = -1;
+
+
+/* GENERIC HELPER FUNCTIONS */
+
+static gchar *
+my_match_strval(guint32 val, const value_string *vs, gint *idx)
+{
+    gint	i = 0;
+
+    while (vs[i].strptr) {
+	if (vs[i].value == val)
+	{
+	    *idx = i;
+	    return(vs[i].strptr);
+	}
+
+	i++;
+    }
+
+    *idx = -1;
+    return(NULL);
+}
+
+/* PARAMETER dissection */
+
+static void
+param_ssCode(ASN1_SCK *asn1, proto_tree *tree, guint len, int hf_field)
+{
+    guint	saved_offset;
+    gint32	value;
+    gchar	*str = NULL;
+
+    hf_field = hf_field;
+
+    saved_offset = asn1->offset;
+    asn1_int32_value_decode(asn1, len, &value);
+
+    switch (value)
+    {
+    case 0x00:
+	str = "allSS - all SS";
+	break;
+
+    case 0x10:
+	str = "allLineIdentificationSS - all line identification SS";
+	break;
+
+    case 0x11:
+	str = "clip - calling line identification presentation";
+	break;
+
+    case 0x12:
+	str = "clir - calling line identification restriction";
+	break;
+
+    case 0x13:
+	str = "colp - connected line identification presentation";
+	break;
+
+    case 0x14:
+	str = "colr - connected line identification restriction";
+	break;
+
+    case 0x15:
+	str = "mci - malicious call identification";
+	break;
+
+    case 0x18:
+	str = "allNameIdentificationSS - all name indentification SS";
+	break;
+
+    case 0x19:
+	str = "cnap - calling name presentation";
+	break;
+
+    case 0x20:
+	str = "allForwardingSS - all forwarding SS";
+	break;
+
+    case 0x21:
+	str = "cfu - call forwarding unconditional";
+	break;
+
+    case 0x28:
+	str = "allCondForwardingSS - all conditional forwarding SS";
+	break;
+
+    case 0x29:
+	str = "cfb - call forwarding busy";
+	break;
+
+    case 0x2a:
+	str = "cfnry - call forwarding on no reply";
+	break;
+
+    case 0x2b:
+	str = "cfnrc - call forwarding on mobile subscriber not reachable";
+	break;
+
+    case 0x24:
+	str = "cd - call deflection";
+	break;
+
+    case 0x30:
+	str = "allCallOfferingSS - all call offering SS includes also all forwarding SS";
+	break;
+
+    case 0x31:
+	str = "ect - explicit call transfer";
+	break;
+
+    case 0x32:
+	str = "mah - mobile access hunting";
+	break;
+
+    case 0x40:
+	str = "allCallCompletionSS - all Call completion SS";
+	break;
+
+    case 0x41:
+	str = "cw - call waiting";
+	break;
+
+    case 0x42:
+	str = "hold - call hold";
+	break;
+
+    case 0x43:
+	str = "ccbs-A - completion of call to busy subscribers, originating side";
+	break;
+
+    case 0x44:
+	str = "ccbs-B - completion of call to busy subscribers, destination side";
+	break;
+
+    case 0x45:
+	str = "mc - multicall";
+	break;
+
+    case 0x50:
+	str = "allMultiPartySS - all multiparty SS";
+	break;
+
+    case 0x51:
+	str = "multiPTY - multiparty";
+	break;
+
+    case 0x60:
+	str = "allCommunityOfInterestSS - all community of interest SS";
+	break;
+
+    case 0x61:
+	str = "cug - closed user group";
+	break;
+
+    case 0x70:
+	str = "allChargingSS - all charging SS";
+	break;
+
+    case 0x71:
+	str = "aoci - advice of charge information";
+	break;
+
+    case 0x72:
+	str = "aocc - advice of charge charging";
+	break;
+
+    case 0x80:
+	str = "allAdditionalInfoTransferSS - all additional information transfer SS";
+	break;
+
+    case 0x81:
+	str = "uus1 - UUS1 user-to-user signalling";
+	break;
+
+    case 0x82:
+	str = "uus2 - UUS2 user-to-user signalling";
+	break;
+
+    case 0x83:
+	str = "uus3 - UUS3 user-to-user signalling";
+	break;
+
+    case 0x90:
+	str = "allBarringSS - all barring SS";
+	break;
+
+    case 0x91:
+	str = "barringOfOutgoingCalls";
+	break;
+
+    case 0x92:
+	str = "baoc - barring of all outgoing calls";
+	break;
+
+    case 0x93:
+	str = "boic - barring of outgoing international calls";
+	break;
+
+    case 0x94:
+	str = "boicExHC - barring of outgoing international calls except those directed to the home PLMN";
+	break;
+
+    case 0x99:
+	str = "barringOfIncomingCalls";
+	break;
+
+    case 0x9a:
+	str = "baic - barring of all incoming calls";
+	break;
+
+    case 0x9b:
+	str = "bicRoam - barring of incoming calls when roaming outside home PLMN Country";
+	break;
+
+    case 0xf0:
+	str = "allPLMN-specificSS";
+	break;
+
+    case 0xa0:
+	str = "allCallPrioritySS - all call priority SS";
+	break;
+
+    case 0xa1:
+	str = "emlpp - enhanced Multilevel Precedence Pre-emption (EMLPP) service";
+	break;
+
+    case 0xb0:
+	str = "allLCSPrivacyException - all LCS Privacy Exception Classes";
+	break;
+
+    case 0xb1:
+	str = "universal - allow location by any LCS client";
+	break;
+
+    case 0xb2:
+	str = "callrelated - allow location by any value added LCS client to which a call is established from the target MS";
+	break;
+
+    case 0xb3:
+	str = "callunrelated - allow location by designated external value added LCS clients";
+	break;
+
+    case 0xb4:
+	str = "plmnoperator - allow location by designated PLMN operator LCS clients";
+	break;
+
+    case 0xc0:
+	str = "allMOLR-SS - all Mobile Originating Location Request Classes";
+	break;
+
+    case 0xc1:
+	str = "basicSelfLocation - allow an MS to request its own location";
+	break;
+
+    case 0xc2:
+	str = "autonomousSelfLocation - allow an MS to perform self location without interaction with the PLMN for a predetermined period of time";
+	break;
+
+    case 0xc3:
+	str = "transferToThirdParty - allow an MS to request transfer of its location to another LCS client";
+	break;
+
+    default:
+	/*
+	 * XXX
+	 */
+	str = "reserved for future use";
+	break;
+    }
+
+    proto_tree_add_text(tree, asn1->tvb, saved_offset, len, str);
+}
+
+/*
+ * See GSM 03.11
+ */
+static void
+param_ssStatus(ASN1_SCK *asn1, proto_tree *tree, guint len, int hf_field)
+{
+    guint	saved_offset;
+    gint32	value;
+    char	bigbuf[1024];
+
+    hf_field = hf_field;
+
+    saved_offset = asn1->offset;
+    asn1_int32_value_decode(asn1, len, &value);
+
+    other_decode_bitfield_value(bigbuf, value, 0xf0, 8);
+    proto_tree_add_text(tree, asn1->tvb,
+	saved_offset, 1,
+	"%s :  Unused",
+	bigbuf);
+
+    /*
+     * Q bit is valid only if A bit is "Active"
+     */
+    other_decode_bitfield_value(bigbuf, value, 0x08, 8);
+    proto_tree_add_text(tree, asn1->tvb,
+	saved_offset, 1,
+	"%s :  Q bit: %s",
+	bigbuf,
+	(value & 0x01) ?
+	    ((value & 0x08) ? "Quiescent" : "Operative") : "N/A");
+
+    other_decode_bitfield_value(bigbuf, value, 0x04, 8);
+    proto_tree_add_text(tree, asn1->tvb,
+	saved_offset, 1,
+	"%s :  P bit: %sProvisioned",
+	bigbuf,
+	(value & 0x04) ? "" : "Not ");
+
+    other_decode_bitfield_value(bigbuf, value, 0x02, 8);
+    proto_tree_add_text(tree, asn1->tvb,
+	saved_offset, 1,
+	"%s :  R bit: %sRegistered",
+	bigbuf,
+	(value & 0x02) ? "" : "Not ");
+
+    other_decode_bitfield_value(bigbuf, value, 0x01, 8);
+    proto_tree_add_text(tree, asn1->tvb,
+	saved_offset, 1,
+	"%s :  A bit: %sActive",
+	bigbuf,
+	(value & 0x01) ? "" : "Not ");
+}
+
+
+typedef enum
+{
+    GSM_SS_P_SS_CODE,			/* SS-Code */
+    GSM_SS_P_SS_STATUS,			/* SS-Status */
+    GSM_SS_P_NONE			/* NONE */
+}
+param_idx_t;
+
+#define	NUM_PARAM_1 (GSM_SS_P_NONE+1)
+static gint ett_param_1[NUM_PARAM_1];
+static void (*param_1_fcn[])(ASN1_SCK *asn1, proto_tree *tree, guint len, int hf_field) = {
+    param_ssCode,			/* SS-Code */
+    param_ssStatus,			/* SS-Status */
+    NULL				/* NONE */
+};
+
+static int *param_1_hf[] = {
+    HF_NULL,				/* SS-Code */
+    HF_NULL,				/* SS-Status */
+    NULL				/* NONE */
+};
+
+#define	GSM_SS_START_SUBTREE(_Gtree, _Gsaved_offset, _Gtag, _Gstr1, _Gett, _Gdef_len_p, _Glen_p, _Gsubtree_p) \
+    { \
+	guint		_len_offset; \
+	proto_item	*_item; \
+ \
+	_len_offset = asn1->offset; \
+	asn1_length_decode(asn1, _Gdef_len_p, _Glen_p); \
+ \
+	_item = \
+	    proto_tree_add_text(_Gtree, asn1->tvb, _Gsaved_offset, -1, _Gstr1); \
+ \
+	_Gsubtree_p = proto_item_add_subtree(_item, _Gett); \
+ \
+	proto_tree_add_text(_Gsubtree_p, asn1->tvb, \
+	    _Gsaved_offset, _len_offset - _Gsaved_offset, "Tag: 0x%02x", _Gtag); \
+ \
+	if (*_Gdef_len_p) \
+	{ \
+	    proto_tree_add_text(_Gsubtree_p, asn1->tvb, \
+		_len_offset, asn1->offset - _len_offset, "Length: %d", *_Glen_p); \
+	} \
+	else \
+	{ \
+	    proto_tree_add_text(_Gsubtree_p, asn1->tvb, \
+		_len_offset, asn1->offset - _len_offset, "Length: Indefinite"); \
+ \
+	    *_Glen_p = tcap_find_eoc(asn1); \
+	} \
+ \
+	proto_item_set_len(_item, (asn1->offset - _Gsaved_offset) + *_Glen_p + \
+	    (*_Gdef_len_p ? 0 : TCAP_EOC_LEN)); \
+    }
+
+
+#define	GSM_SS_PARAM_DISPLAY(Gtree, Goffset, Gtag, Ga1, Ga2) \
+    { \
+	gint		_ett_param_idx; \
+	guint		_len; \
+	void		(*_param_fcn)(ASN1_SCK *asn1, proto_tree *tree, guint len, int hf_field) = NULL; \
+	int		*_param_hf = NULL; \
+	proto_tree	*_subtree; \
+	gboolean	_def_len; \
+ \
+	if (Ga1 == GSM_SS_P_NONE) \
+	{ \
+	    _ett_param_idx = gsm_ss_ett_param; \
+	    _param_fcn = NULL; \
+	    _param_hf = HF_NULL; \
+	} \
+	else \
+	{ \
+	    _ett_param_idx = ett_param_1[Ga1]; \
+	    _param_fcn = param_1_fcn[Ga1]; \
+	    _param_hf = param_1_hf[Ga1]; \
+	} \
+ \
+	GSM_SS_START_SUBTREE(Gtree, Goffset, Gtag, Ga2, _ett_param_idx, &_def_len, &_len, _subtree); \
+ \
+	if (_len > 0) \
+	{ \
+	    if (Ga1 == GSM_SS_P_NONE || _param_fcn == NULL) \
+	    { \
+		proto_tree_add_text(_subtree, asn1->tvb, \
+		    asn1->offset, _len, "Parameter Data"); \
+ \
+		asn1->offset += _len; \
+	    } \
+	    else \
+	    { \
+		(*_param_fcn)(asn1, _subtree, _len, *_param_hf); \
+	    } \
+	} \
+ \
+	if (!_def_len) \
+	{ \
+	    guint	_saved_offset; \
+ \
+	    _saved_offset = asn1->offset; \
+	    asn1_eoc_decode(asn1, -1); \
+ \
+	    proto_tree_add_text(Gtree, asn1->tvb, \
+		_saved_offset, asn1->offset - _saved_offset, "End of Contents"); \
+	} \
+    }
+
+
+static void
+op_generic_ss(ASN1_SCK *asn1, proto_tree *tree, guint exp_len)
+{
+    guint	orig_offset, saved_offset, len_offset;
+    guint	tag, len;
+    gboolean	def_len = FALSE;
+    proto_item	*item;
+    proto_tree	*subtree;
+
+    orig_offset = asn1->offset;
+
+    while ((tvb_length_remaining(asn1->tvb, asn1->offset) > 0) &&
+	(!tcap_check_tag(asn1, 0)))
+    {
+	if ((exp_len != 0) &&
+	    ((asn1->offset - orig_offset) >= exp_len))
+	{
+	    break;
+	}
+
+	saved_offset = asn1->offset;
+	asn1_id_decode1(asn1, &tag);
+
+	if (TCAP_CONSTRUCTOR(tag))
+	{
+	    GSM_SS_START_SUBTREE(tree, saved_offset, tag, "Sequence",
+		gsm_ss_ett_sequence,
+		&def_len, &len, subtree);
+
+	    op_generic_ss(asn1, subtree, len);
+
+	    if (!def_len)
+	    {
+		saved_offset = asn1->offset;
+		asn1_eoc_decode(asn1, -1);
+
+		proto_tree_add_text(subtree, asn1->tvb,
+		    saved_offset, asn1->offset - saved_offset, "End of Contents");
+	    }
+	    continue;
+	}
+
+	len_offset = asn1->offset;
+	asn1_length_decode(asn1, &def_len, &len);
+
+	if (!def_len)
+	{
+	    proto_tree_add_text(tree, asn1->tvb,
+		saved_offset, len_offset - saved_offset,
+		"Tag: 0x%02x", tag);
+
+	    proto_tree_add_text(tree, asn1->tvb,
+		len_offset, asn1->offset - len_offset, "Length: Indefinite");
+
+	    len = tcap_find_eoc(asn1);
+
+	    op_generic_ss(asn1, tree, len);
+
+	    saved_offset = asn1->offset;
+	    asn1_eoc_decode(asn1, -1);
+
+	    proto_tree_add_text(tree, asn1->tvb,
+		saved_offset, asn1->offset - saved_offset, "End of Contents");
+	    continue;
+	}
+
+	item =
+	    proto_tree_add_text(tree, asn1->tvb,
+		saved_offset, (asn1->offset - saved_offset) + len, "Parameter");
+
+	subtree = proto_item_add_subtree(item, gsm_ss_ett_param);
+
+	proto_tree_add_text(subtree, asn1->tvb,
+	    saved_offset, len_offset - saved_offset,
+	    "Tag: 0x%02x", tag);
+
+	proto_tree_add_text(subtree, asn1->tvb,
+	    len_offset, asn1->offset - len_offset, "Length: %d", len);
+
+	if (len > 0)
+	{
+	    proto_tree_add_text(subtree, asn1->tvb,
+		asn1->offset, len, "Parameter Data");
+
+	    asn1->offset += len;
+	}
+    }
+}
+
+static void
+op_interrogate_ss(ASN1_SCK *asn1, proto_tree *tree, guint exp_len)
+{
+    guint	saved_offset, start_offset;
+    guint	tag, len;
+    gboolean	def_len = FALSE;
+    proto_tree	*subtree;
+
+    exp_len = exp_len;
+
+    if (tvb_length_remaining(asn1->tvb, asn1->offset) <= 0) return;
+
+    saved_offset = asn1->offset;
+    asn1_id_decode1(asn1, &tag);
+
+    if (TCAP_CONSTRUCTOR(tag) == FALSE)
+    {
+	/*
+	 * Hmmm, unexpected
+	 */
+	return;
+    }
+
+    GSM_SS_START_SUBTREE(tree, saved_offset, tag, "Sequence",
+	gsm_ss_ett_sequence,
+	&def_len, &len, subtree);
+
+    start_offset = asn1->offset;
+
+    saved_offset = asn1->offset;
+    asn1_id_decode1(asn1, &tag);
+
+    GSM_SS_PARAM_DISPLAY(subtree, saved_offset, tag, GSM_SS_P_SS_CODE, "SS-Code");
+
+    op_generic_ss(asn1, subtree, len - (asn1->offset - start_offset));
+
+    if (!def_len)
+    {
+	saved_offset = asn1->offset;
+	asn1_eoc_decode(asn1, -1);
+
+	proto_tree_add_text(subtree, asn1->tvb,
+	    saved_offset, asn1->offset - saved_offset, "End of Contents");
+    }
+}
+
+static void
+op_interrogate_ss_rr(ASN1_SCK *asn1, proto_tree *tree, guint exp_len)
+{
+    guint	saved_offset;
+    guint	tag;
+
+    exp_len = exp_len;
+
+    if (tvb_length_remaining(asn1->tvb, asn1->offset) <= 0) return;
+
+    saved_offset = asn1->offset;
+    asn1_id_decode1(asn1, &tag);
+
+    switch (tag)
+    {
+    case 0x80:	/* SS-Status */
+	GSM_SS_PARAM_DISPLAY(tree, saved_offset, tag, GSM_SS_P_SS_STATUS, "SS-Status");
+	return;
+
+    case 0x82:	/* BasicServiceGroupList */
+	/* FALLTHRU */
+    case 0x83:	/* ForwardingFeatureList */
+	/* FALLTHRU */
+
+    case 0x84:	/* GenericServiceInfo */
+	/*
+	 * XXX
+	 * needs implementing, let "generic" parameter dissector handle it for now
+	 */
+	break;
+
+    default:
+	/* do nothing - unexpected tag */
+	break;
+    }
+
+    op_generic_ss(asn1, tree, 0);
+}
+
+#define	GSM_SS_NUM_OP (sizeof(gsm_ss_opr_code_strings)/sizeof(value_string))
+static void (*op_fcn[])(ASN1_SCK *asn1, proto_tree *tree, guint exp_len) = {
+    NULL,	/* RegisterSS */
+    NULL,	/* EraseSS */
+    NULL,	/* ActivateSS */
+    NULL,	/* DeactivateSS */
+    op_interrogate_ss,	/* InterrogateSS */
+    NULL,	/* NotifySS */
+    NULL,	/* RegisterPassword */
+    NULL,	/* GetPassword */
+    NULL,	/* ProcessUnstructuredSS-Data */
+    NULL,	/* ForwardCheckSS-Indication */
+    NULL,	/* ProcessUnstructuredSS-Request */
+    NULL,	/* UnstructuredSS-Request */
+    NULL,	/* UnstructuredSS-Notify */
+    NULL,	/* EraseCC-Entry */
+    NULL,	/* AccessRegisterCCEntry */
+    NULL,	/* ForwardCUG-Info */
+    NULL,	/* SplitMPTY */
+    NULL,	/* RetrieveMPTY */
+    NULL,	/* HoldMPTY */
+    NULL,	/* BuildMPTY */
+    NULL,	/* ForwardChargeAdvice */
+    NULL,	/* ExplicitCT */
+
+    NULL	/* NONE */
+};
+
+static void (*op_fcn_rr[])(ASN1_SCK *asn1, proto_tree *tree, guint exp_len) = {
+    NULL,	/* RegisterSS */
+    NULL,	/* EraseSS */
+    NULL,	/* ActivateSS */
+    NULL,	/* DeactivateSS */
+    op_interrogate_ss_rr,	/* InterrogateSS */
+    NULL,	/* NotifySS */
+    NULL,	/* RegisterPassword */
+    NULL,	/* GetPassword */
+    NULL,	/* ProcessUnstructuredSS-Data */
+    NULL,	/* ForwardCheckSS-Indication */
+    NULL,	/* ProcessUnstructuredSS-Request */
+    NULL,	/* UnstructuredSS-Request */
+    NULL,	/* UnstructuredSS-Notify */
+    NULL,	/* EraseCC-Entry */
+    NULL,	/* AccessRegisterCCEntry */
+    NULL,	/* ForwardCUG-Info */
+    NULL,	/* SplitMPTY */
+    NULL,	/* RetrieveMPTY */
+    NULL,	/* HoldMPTY */
+    NULL,	/* BuildMPTY */
+    NULL,	/* ForwardChargeAdvice */
+    NULL,	/* ExplicitCT */
+
+    NULL	/* NONE */
+};
+
+void
+gsm_ss_dissect(ASN1_SCK *asn1, proto_tree *tree, guint exp_len,
+    guint opr_code, guint comp_type_tag)
+{
+    void (*dissect_fcn)(ASN1_SCK *asn1, proto_tree *tree, guint exp_len);
+    gchar	*str;
+    gint	op_idx;
+
+
+    dissect_fcn = NULL;
+
+    str = my_match_strval(opr_code, gsm_ss_opr_code_strings, &op_idx);
+
+    if (str != NULL)
+    {
+	switch (comp_type_tag)
+	{
+	case TCAP_COMP_INVOKE:
+	    dissect_fcn = op_fcn[op_idx];
+	    break;
+
+	case TCAP_COMP_RRL:
+	    dissect_fcn = op_fcn_rr[op_idx];
+	    break;
+
+	case TCAP_COMP_RE:
+	    /* XXX */
+	    break;
+
+	default:
+	    /*
+	     * no parameters should be present in the component types
+	     * ignore
+	     */
+	    return;
+	}
+    }
+
+    if (dissect_fcn == NULL)
+    {
+	op_generic_ss(asn1, tree, exp_len);
+    }
+    else
+    {
+	(*dissect_fcn)(asn1, tree, exp_len);
+    }
+}