/src/wireshark/epan/dissectors/packet-sgsap.c

Source
/* packet-sgsap.c
 * Routines for SGs Application Part (SGsAP) protocol dissection
 *
 * Copyright 2010 - 2017, Anders Broman <anders.broman@ericsson.com>
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * References: 3GPP TS 29.118 V10.2.0 (2010-12)
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/tfs.h>
#include <epan/expert.h>
#include <epan/exceptions.h>
#include <epan/show_exception.h>

#include <wsutil/array.h>
#include "packet-gsm_a_common.h"
#include "packet-e212.h"

void proto_register_sgsap(void);
void proto_reg_handoff_sgsap(void);

/* Global variables */
static dissector_handle_t gsm_a_dtap_handle;

/* The registered SCTP port number for SGsAP is 29118.
 * The payload protocol identifier to be used for SGsAP is 0.
 */
#define SGSAP_SCTP_PORT_RANGE "29118"

/* Initialize the protocol and registered fields */
static int proto_sgsap;

static int hf_sgsap_msg_type;
int hf_sgsap_elem_id;
static int hf_sgsap_eps_location_update_type;
static int hf_sgsap_service_indicator_value;
static int hf_sgsap_sgs_cause;
static int hf_sgsap_ue_emm_mode;
static int hf_sgsap_eci;
static int hf_sgsap_cn_id;
static int hf_sgsap_imsi_det_eps;
static int hf_sgsap_imsi_det_non_eps;
static int hf_sgsap_lcs_indic;
static int hf_sgsap_mme_name;
static int hf_sgsap_vlr_name;
static int hf_sgsap_imeisv;
static int hf_sgsap_unknown_msg;
static int hf_sgsap_message_elements;
static int hf_sgsap_csri;
static int hf_sgsap_sel_cs_dmn_op;

static int ett_sgsap;
static int ett_sgsap_sel_cs_dmn_op;

static expert_field ei_sgsap_extraneous_data;
static expert_field ei_sgsap_missing_mandatory_element;

static dissector_handle_t sgsap_handle;

static void get_sgsap_msg_params(uint8_t oct, const char **msg_str, int *ett_tree, int *hf_idx, msg_fcn *msg_fcn_p);

/*
 * 9.4  Information elements
 */
/*
 * 9.4.1    CLI
 */

/*
 * Octets 3 to 14 contain the value part of the Calling party BCD number information element
 * defined in subclause 10.5.4.9 of 3GPP TS 24.008 [8] (octets 3 to 14, i.e. not including
 * 3GPP TS 24.008 IEI and 3GPP TS 24.008 length indicator)
 * ( packet-gsm_a_dtap.c )
 */
/*
 * 9.4.2    EPS location update type
 */

/* EPS location update type value (octet 3) */
static const value_string sgsap_eps_location_update_type_values[] = {
    { 0x00, "Shall not be sent in this version of the protocol" },
    { 0x01, "IMSI attach" },
    { 0x02, "Normal location update" },
    { 0, NULL }
};

static uint16_t
de_sgsap_eps_loc_upd_type(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;
    uint8_t oct;

    curr_offset = offset;

    /* Octet 3  EPS location update type value */
    proto_tree_add_item(tree, hf_sgsap_eps_location_update_type, tvb, offset, 1, ENC_BIG_ENDIAN);
    if (add_string) {
        oct = tvb_get_uint8(tvb, curr_offset);
        snprintf(add_string, string_len, " - %s", val_to_str_const(oct, sgsap_eps_location_update_type_values, "Reserved"));
    }

    curr_offset++;

    return curr_offset - offset;
}
/*
 * 9.4.3    Erroneous message
 *
 * See subclause 18.4.5 in 3GPP TS 29.018 [16].
 */
static uint16_t
de_sgsap_err_msg(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len, char *add_string , int string_len)
{
    const char      *msg_str;
    int              ett_tree;
    int              hf_idx;
    void(*msg_fcn_p)(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len);
    uint8_t         oct;

    /* 18.4.5 Erroneous message
     * The Erroneous message IE is a TLV IE that encapsulates the message in error.
     * Octet 3 - Octet n
     * Erroneous message including the message type.
     */
     /* Message type IE*/
    oct = tvb_get_uint8(tvb, offset);
    msg_fcn_p = NULL;
    ett_tree = -1;
    hf_idx = -1;
    msg_str = NULL;

    proto_tree_add_item(tree, hf_sgsap_msg_type, tvb, offset, 1, ENC_BIG_ENDIAN);

    get_sgsap_msg_params(oct, &msg_str, &ett_tree, &hf_idx, &msg_fcn_p);
    if (msg_str) {
        if (add_string)
            snprintf(add_string, string_len, " - %s", msg_str);

    }
    if (msg_fcn_p){
        volatile uint32_t curr_offset = offset + 1;
        TRY {
            /*let's try to decode erroneous message and catch exceptions as it could be malformed */
            (*msg_fcn_p)(tvb, tree, pinfo, curr_offset, len - 1);
        } CATCH_BOUNDS_ERRORS {
            show_exception(tvb, pinfo, tree, EXCEPT_CODE, GET_MESSAGE);
        } ENDTRY
    }


    return len;
}
/*
 * 9.4.3a   E-UTRAN Cell Global Identity
 *
 * The coding of the E-UTRAN Cell Global Identity value is according to ECGI field information element
 * as specified in subclause 8.21.5 of 3GPP TS 29.274 [17A] (GTPv2-C)
 */
uint16_t
de_sgsap_ecgi(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t   curr_offset;

    curr_offset = offset;

    dissect_e212_mcc_mnc(tvb, pinfo, tree, offset, E212_ECGI, true);
    curr_offset += 3;

    proto_tree_add_item(tree, hf_sgsap_eci, tvb, curr_offset, 4, ENC_BIG_ENDIAN);
    curr_offset += 4;

    return curr_offset-offset;
}
/*
 * 9.4.4    Global CN-Id
 *
 * See subclause 18.4.27 in 3GPP TS 29.018 [16].
 * 18.4.27 Global CN-Id
 * The Global CN-Id consists of a PLMN-Id and a CN-Id, see 3GPP TS 23.003. The PLMN-Id consists of MCC and MNC
 * coded according to Location Area Identification in 3GPP TS 24.008. The CN-Id is an integer defined by O&M. The
 * least significant bit of the CN-Id field is bit 1 of octet 7 and the most significant bit is bit 8 of octet 6. If the CN-Id does
 * not fill the field reserved for it, the rest of the bits are set to '0'.
 */
static uint16_t
de_sgsap_g_cn_id(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t   curr_offset;

    curr_offset = offset;

    dissect_e212_mcc_mnc(tvb, pinfo, tree, offset, E212_NONE, true);
    curr_offset += 3;

    proto_tree_add_item(tree, hf_sgsap_cn_id, tvb, curr_offset, 2, ENC_BIG_ENDIAN);
    curr_offset += 2;

    return curr_offset-offset;
}
/*
 * 9.4.5    IMEISV
 * See subclause 18.4.9 in 3GPP TS 29.018 [16].
 * The IMEISV is coded as a sequence of BCD digits, compressed two into each octet.
 * The IMEISV consists of 16 digits
 * (see 3GPP TS 23.003).
 */
static uint16_t
de_sgsap_imeisv(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    char       *imeisv_str;
    uint32_t    curr_offset;

    curr_offset = offset;

    proto_tree_add_item_ret_display_string(tree, hf_sgsap_imeisv, tvb, curr_offset, len, ENC_BCD_DIGITS_0_9|ENC_LITTLE_ENDIAN, pinfo->pool, &imeisv_str);
    if (add_string) {
        /* (len<<2)+4 = the maximum number of bytes to produce (including the terminating nul character). */
        snprintf(add_string, (len<<2)+4, " - %s", imeisv_str);
    }

    return len;
}

/*
 * 9.4.6    IMSI
 * See subclause 18.4.10 in 3GPP TS 29.018 [16].
 */
/* The IMSI is coded as a sequence of BCD digits, compressed two into each octet.
 * This is a variable length element, and includes a length indicator.
 * The IMSI is defined in 3GPP TS 23.003. It shall not exceed 15 digits (see 3GPP TS 23.003).
 */
/*
 * 9.4.7    IMSI detach from EPS service type
 */

/* IMSI detach from EPS service type value (octet 3) */
static const value_string sgsap_imsi_det_from_eps_serv_type_values[] = {
    { 0x00, "Interpreted as reserved in this version of the protocol" },
    { 0x01, "Network initiated IMSI detach from EPS services" },
    { 0x02, "UE initiated IMSI detach from EPS services" },
    { 0x03, "EPS services not allowed" },
    { 0, NULL }
};

static uint16_t
de_sgsap_imsi_det_eps(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;

    proto_tree_add_item(tree, hf_sgsap_imsi_det_eps, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset += 1;

    return curr_offset-offset;
}
/*
 * 9.4.8    IMSI detach from non-EPS service type
 */
/* IMSI detach from non-EPS service type value (octet 3)*/
static const value_string sgsap_imsi_det_from_non_eps_serv_type_values[] = {
    { 0x00, "Interpreted as reserved in this version of the protocol" },
    { 0x01, "Explicit UE initiated IMSI detach from non-EPS services" },
    { 0x02, "Combined UE initiated IMSI detach from EPS and non-EPS services" },
    { 0x03, "Implicit network initiated IMSI detach from non-EPS services" },
    { 0, NULL }
};

static uint16_t
de_sgsap_imsi_det_non_eps(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;

    proto_tree_add_item(tree, hf_sgsap_imsi_det_non_eps, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset += 1;

    return curr_offset-offset;
}
/*
 * 9.4.9    LCS client identity
 * The coding of the LCS client identity value is according to LCS-ClientID
 * as specified in subclause 17.7.13 of 3GPP TS 29.002 [15]
 * (packet-nas_eps.c)
 */
/*
 * 9.4.10   LCS indicator
 */
static const value_string sgsap_lcs_indic_values[] = {
    { 0x00, "Normal, unspecified in this version of the protocol" },
    { 0x01, "MT-LR" },
    { 0, NULL }
};

static uint16_t
de_sgsap_lcs_indic(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;

    proto_tree_add_item(tree, hf_sgsap_lcs_indic, tvb, curr_offset, 1, ENC_BIG_ENDIAN);
    curr_offset += 1;

    return curr_offset-offset;
}
/*
 * 9.4.11   Location area identifier
 *
 * Octets 3 to 7 contain the value part of the Location area identification information element
 * defined in 3GPP TS 24.008 [8] (starting with octet 2, i.e. not including 3GPP TS 24.008 IEI)
 *(packet-gsm_a_common.c)
 */
/*
 * 9.4.12   MM information
 * For the coding see subclause 18.4.16 in 3GPP TS 29.018 [16].
 * User information: This field is composed of one or more of the
 * information elements of the MM information message as defined in
 * 3GPP TS 24.008, excluding the Protocol discriminator, Skip
 * indicator and Message type. This field includes the IEI and length
 * indicator of the other information elements.
 */
static uint16_t
de_sgsap_mm_info(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;

    dtap_mm_mm_info(tvb, tree, pinfo, curr_offset, len);

    return len;
}

/*
 * 9.4.13   MME name
 */
static uint16_t
de_sgsap_mme_name(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    unsigned   name_len;
    char *fqdn = NULL;

    /* The MME name information element specifies the MME name and is coded as shown in figure 9.4.13.1. Octets 3
     * through n contain the name in the form of a fully qualified domain name (FQDN) as specified in 3GPP TS 23.003 [3].
     * The value part of the MME name information element (not including IEI and length indicator) shall have a length of 55
     * octets.
     */
    if (len > 0) {
        name_len = tvb_get_uint8(tvb, offset);

        if (name_len < 0x20) {
            fqdn = (char*)tvb_get_string_enc(pinfo->pool, tvb, offset, len, ENC_APN_STR);
        } else{
            fqdn = (char*)tvb_get_string_enc(pinfo->pool, tvb, offset, len, ENC_ASCII);
        }
        proto_tree_add_string(tree, hf_sgsap_mme_name, tvb, offset, len, fqdn);
        if (add_string)
            snprintf(add_string, string_len, " - %s", fqdn);

    }

    return len;
}
/*
 * 9.4.14   Mobile identity
 * See subclause 18.4.17 in 3GPP TS 29.018 [16].
 * (packet-gsm_a_common.c)
 */
/*
 * 9.4.14a  Mobile Station Classmark 2
 * With the exception of the IEI, the contents are specified in subclause 10.5.1.6 in 3GPP TS 24.008 [8].
 * (packet-gsm_a_common.c)
 */
/*
 * 9.4.15   NAS message container
 * Octets 3 to 253 contain the SMS message (i.e. CP DATA, CP ACK or CP ERROR)
 * as defined in subclause 7.2 of 3GPP TS 24.011 [10]
 */
static uint16_t
de_sgsap_nas_msg_container(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len, char *add_string _U_, int string_len _U_)
{
    tvbuff_t *new_tvb;
    uint32_t curr_offset;

    curr_offset = offset;

    /* Octets 3 to 253 contain the SMS message (i.e. CP DATA, CP ACK or CP ERROR)
     * as defined in subclause 7.2 of 3GPP TS 24.011 [10]
     */
    new_tvb = tvb_new_subset_length(tvb, curr_offset, len);
    if (gsm_a_dtap_handle) {
        call_dissector(gsm_a_dtap_handle, new_tvb, pinfo, tree);
    }

    return len;
}
/*
 * 9.4.16   Reject cause
 * See subclause 18.4.21 in 3GPP TS 29.018 [16].
 * The rest of the information element is coded as the value part of
 * the reject cause IE defined in 3GPP TS 24.008, not including
 * 3GPP TS 24.008 IEI.
 * (packet-gsm_a_dtap.c)
 */
/*
 * 9.4.17   Service indicator
 */

/* Octet 3  Service indicator value */
static const value_string sgsap_service_indicator_values[] = {
    { 0x00, "Shall not be sent in this version of the protocol" },
    { 0x01, "CS call indicator" },
    { 0x02, "SMS indicator" },
    { 0, NULL }
};

static uint16_t
de_sgsap_serv_indic(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;
    uint8_t oct;

    curr_offset = offset;

    /* Octet 3  Service indicator value */
    proto_tree_add_item(tree, hf_sgsap_service_indicator_value, tvb, offset, 1, ENC_BIG_ENDIAN);
    if (add_string) {
        oct = tvb_get_uint8(tvb, curr_offset);
        snprintf(add_string, string_len, " - %s", val_to_str_const(oct, sgsap_service_indicator_values, "Reserved"));
    }
    curr_offset++;

    return curr_offset-offset;
}
/*
 * 9.4.18   SGs cause
 */

/* SGs cause value (octet 3) */
static const value_string sgsap_sgs_cause_values[] = {
    { 0x00, "Normal, unspecified in this version of the protocol" },
    { 0x01, "IMSI detached for EPS services" },
    { 0x02, "IMSI detached for EPS and non-EPS services" },
    { 0x03, "IMSI unknown" },
    { 0x04, "IMSI detached for non-EPS services" },
    { 0x05, "IMSI implicitly detached for non-EPS services" },
    { 0x06, "UE unreachable" },
    { 0x07, "Message not compatible with the protocol state" },
    { 0x08, "Missing mandatory information element" },
    { 0x09, "Invalid mandatory information" },
    { 0x0a, "Conditional information element error" },
    { 0x0b, "Semantically incorrect message" },
    { 0x0c, "Message unknown" },
    { 0x0d, "Mobile terminating CS fallback call rejected by the user" },
    { 0x0e, "UE temporarily unreachable" },
    { 0, NULL }
};

static value_string_ext sgsap_sgs_cause_values_ext = VALUE_STRING_EXT_INIT(sgsap_sgs_cause_values);

static uint16_t
de_sgsap_sgs_cause(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;
    uint8_t oct;

    curr_offset = offset;

    proto_tree_add_item(tree, hf_sgsap_sgs_cause, tvb, offset, 1, ENC_BIG_ENDIAN);
    if (add_string) {
        oct = tvb_get_uint8(tvb, curr_offset);
        snprintf(add_string, string_len, " - %s", val_to_str_ext_const(oct, &sgsap_sgs_cause_values_ext, "Reserved"));
    }
    curr_offset++;

    return curr_offset-offset;
}
/*
 * 9.4.19   SS code
 * The coding of the SS code value is according to SS-Code as specified in
 * subclause 17.7.5 of 3GPP TS 29.002 [15]
 * ( packet-nas_eps.c)
 */
/*
 * 9.4.20   TMSI
 * See subclause 18.4.23 in 3GPP TS 29.018 [16].
 * (packet-gsm_a_bssmap.c)
 */

/*
 * 9.4.21   TMSI status
 *
 * See subclause 18.4.24 in 3GPP TS 29.018 [16].
 * (packet-gsm_a_gm.c)
 */
/*
 * 9.4.21a  Tracking Area Identity
 * Octets 3 to 7 contain the value part of the Tracking Area Identity information element defined in 3GPP TS 24.301 [14]
 * (starting with octet 2, i.e. not including 3GPP TS 24.301 IEI)
 * (packet-nas_eps.c)
 */
/*
 * 9.4.21b  UE Time Zone
 * The coding of the UE Time Zone value is according to value part of the Time Zone information element as specified
 * in subclause 10.5.3.8 of 3GPP TS 24.008 [8] (i.e. not including 3GPP TS 24.008 IEI)
 * (packet-gsm_a_dtap.c)
 */
/*
 * 9.4.21c  UE EMM mode
 */
static const value_string sgsap_ue_emm_mode_values[] = {
    { 0x00, "EMM-IDLE" },
    { 0x01, "EMM-CONNECTED" },
    { 0, NULL }
};

static uint16_t
de_sgsap_ue_emm_mode(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    uint32_t curr_offset;

    curr_offset = offset;

    proto_tree_add_item(tree, hf_sgsap_ue_emm_mode, tvb, offset, 1, ENC_BIG_ENDIAN);
    curr_offset += 1;

    return curr_offset-offset;
}
/*
 * 9.4.22   VLR name
 */
static uint16_t
de_sgsap_vlr_name(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    unsigned  name_len;
    char *fqdn = NULL;

    /* The VLR name information element specifies the VLR name and is coded as shown in figure 9.4.22.1.
     * Octets 3 through n contain the VLR name in the form of a fully qualified domain name (FQDN)
     * as specified in IETF RFC 1035 [21].
     */
    if (len > 0) {
        name_len = tvb_get_uint8(tvb, offset);

        if (name_len < 0x20) {
            fqdn = (char*)tvb_get_string_enc(pinfo->pool, tvb, offset, len, ENC_APN_STR);
        } else{
            fqdn = (char*)tvb_get_string_enc(pinfo->pool, tvb, offset, len, ENC_ASCII);
        }
        proto_tree_add_string(tree, hf_sgsap_vlr_name, tvb, offset, len, fqdn);
        if (add_string)
            snprintf(add_string, string_len, " - %s", fqdn);
    }

    return len;
}

/*
 * 9.4.23   Channel needed
 * See subclause 18.4.2 in 3GPP TS 29.018 [16].
 * The rest of the information element is coded as the IEI part and the
 * value part of the Channel Needed IE defined in 3GPP TS 44.018
 * (packet-gsm_a_bssmap.c)
 */
/*
 * 9.4.24   eMLPP priority
 * See subclause 18.4.4 in 3GPP TS 29.018 [16].
 * The rest of the information element is coded as the value part of
 * the eMLPP-Priority IE defined in 3GPP TS 48.008 (not including
 * 3GPP TS 48.008 IEI and 3GPP TS 48.008 length indicator).
 * (packet-gsm_a_bssmap.c)
 */

/*
 *
 */
static uint16_t
de_sgsap_add_paging_ind(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    /* Octet 3 0 0 0 0 0 0 0 CSRI */
    proto_tree_add_item(tree, hf_sgsap_csri, tvb, offset, 1, ENC_BIG_ENDIAN);

    return len;
}

#if 0
Reuse GSM_A_PDU_TYPE_GM, DE_NET_RES_ID_CONT
/*
 * 9.4.26 TMSI based NRI container
 */
static uint16_t
de_sgsap_tmsi_based_nri_cont(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{

    /* See subclause 18.4.28 in 3GPP TS 29.018 [16].
     * Which says The TMSI based NRI container value value consists of 10 bits which correspond to bits 23 to 14 of the valid TMSI
     * (3GPP TS 23.236 and
     * Octet 3 and Octet 4 The rest of the information element is coded as the value part of the Network resource identifier container IE
     * defined in 3GPP TS 24.008.
     */
    return len;
}
#endif
/*
* 9.4.27 Selected CS domain operator
*/
static uint16_t
de_sgsap_selected_cs_dmn_op(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len _U_, char *add_string _U_, int string_len _U_)
{
    proto_item *item;
    proto_tree *sub_tree;
    /* Coded as octets 2 to 4 of the Location Area Identification IE,
     * defined in 3GPP TS 24.008 [8] (not including 3GPP TS 24.008 IEI
     * and LAC).(10.5.1.3 Location Area Identification)
     * MCC digit 2 MCC digit 1 octet 2
     * MNC digit 3 MCC digit 3 octet 3
     * MNC digit 2 MNC digit 1 octet 4
     */
    item = proto_tree_add_item(tree, hf_sgsap_sel_cs_dmn_op, tvb, offset, 1, ENC_NA);
    sub_tree = proto_item_add_subtree(item, ett_sgsap_sel_cs_dmn_op);

    dissect_e212_mcc_mnc_wmem_packet_str(tvb, pinfo, sub_tree, offset, E212_LAI, true);

    return len;
}

static const value_string sgsap_elem_strings[] = {
    { DE_SGSAP_IMSI, "IMSI" },                                              /* 9.4.6 */
    { DE_SGSAP_VLR_NAME, "VLR name" },                                      /* 9.4.22 */
    { DE_SGSAP_TMSI, "TMSI" },                                              /* 9.4.20 */
    { DE_SGSAP_LOC_AREA_ID, "Location area identifier" },                   /* 9.4.11 */
    { DE_SGSAP_CH_NEEDED, "Channel Needed" },                               /* 9.4.23 */
    { DE_SGSAP_EMLPP_PRIO, "eMLPP Priority" },                              /* 9.4.24 */
    { DE_SGSAP_TMSI_STATUS, "TMSI status" },                                /* 9.4.21 */
    { DE_SGSAP_SGS_CAUSE, "SGs cause" },                                    /* 9.4.18 */
    { DE_SGSAP_MME_NAME, "MME name" },                                      /* 9.4.13 */
    { DE_SGSAP_EPS_LOC_UPD_TYPE, "EPS location update type" },              /* 9.4.2 */
    { DE_SGSAP_GLOBAL_CN_ID, "Global CN-Id" },                              /* 9.4.4 */

    { DE_SGSAP_UDEF_11, "Undefined" },                                      /*  */
    { DE_SGSAP_UDEF_12, "Undefined" },                                      /*  */

    { DE_SGSAP_MID, "Mobile identity" },                                    /* 9.4.14 */
    { DE_SGSAP_REJ_CAUSE, "Reject cause" },                                 /* 9.4.16 */
    { DE_SGSAP_IMSI_DET_EPS, "IMSI detach from EPS service type" },         /* 9.4.7 */
    { DE_SGSAP_IMSI_DET_NON_EPS, "IMSI detach from non-EPS service type" }, /* 9.4.8 */

    { DE_SGSAP_IMEISV, "IMEISV" },                                          /* 9.4.5 */
    { DE_SGSAP_NAS_MSG_CONTAINER, "NAS message container" },                /* 9.4.15 */
    { DE_SGSAP_MM_INFO, "MM information" },                                 /* 9.4.12 */

    { DE_SGSAP_UDEF_20, "Undefined" },                                      /*  */
    { DE_SGSAP_UDEF_21, "Undefined" },                                      /*  */
    { DE_SGSAP_UDEF_22, "Undefined" },                                      /*  */

    { DE_SGSAP_ERR_MSG, "Erroneous message" },                              /* 9.4.3 */
    { DE_SGSAP_CLI, "CLI" },                                                /* 9.4.1 */
    { DE_SGSAP_LCS_CLIENT_ID, "LCS client identity" },                      /* 9.4.9 */
    { DE_SGSAP_LCS_INDIC, "LCS indicator" },                                /* 9.4.10 */
    { DE_SGSAP_SS_CODE, "SS code" },                                        /* 9.4.19 */
    { DE_SGSAP_SERV_INDIC, "Service indicator" },                           /* 9.4.17 */
    { DE_SGSAP_UE_TZ, "UE Time Zone" },                                     /* 9.4.21b */
    { DE_SGSAP_MSC_2, "Mobile Station Classmark 2" },                       /* 9.4.14a */
    { DE_SGSAP_TAID, "Tracking Area Identity" },                            /* 9.4.21a */
    { DE_SGSAP_ECGI, "E-UTRAN Cell Global Identity" },                      /* 9.4.3a */
    { DE_SGSAP_UE_EMM_MODE, "UE EMM mode" },                                /* 9.4.21c */
    { DE_SGSAP_ADD_PAGING_IND, "Additional paging indicators" },            /* 9.4.25 */
    { DE_SGSAP_TMSI_BASED_NRI_CONT, "TMSI based NRI container" },           /* 9.4.26 */
    { DE_SGSAP_SELECTED_CS_DMN_OP, "Selected CS domain operator" },         /* 9.4.27 */
    { 0, NULL }
};
value_string_ext sgsap_elem_strings_ext = VALUE_STRING_EXT_INIT(sgsap_elem_strings);

#define NUM_SGSAP_ELEM array_length(sgsap_elem_strings)
int ett_sgsap_elem[NUM_SGSAP_ELEM];
#if 0
This enum has been moved to packet-gsm_a_common to
make it possible to use element dissecton from this dissector
in other dissectors.
It is left here as a comment for easier reference.

Note this enum must be of the same size as the element decoding list

typedef enum
{

    DE_SGSAP_IMSI,                                  /. 9.4.6 IMSI./
    DE_SGSAP_VLR_NAME,                              /. 9.4.22 VLR name./
    DE_SGSAP_TMSI,                                  /. 9.4.20 TMSI ./
    DE_SGSAP_LOC_AREA_ID,                           /. 9.4.11 Location area identifier ./
    DE_SGSAP_CH_NEEDED,                             /. 9.4.23 Channel Needed ./
    DE_SGSAP_EMLPP_PRIO,                            /. 9.4.24 eMLPP Priority./
    DE_SGSAP_TMSI_STATUS,                           /. 9.4.21 TMSI status ./
    DE_SGSAP_SGS_CAUSE,                             /. 9.4.18 SGs cause./
    DE_SGSAP_MME_NAME,                              /. 9.4.13 MME name./
    DE_SGSAP_EPS_LOC_UPD_TYPE,                      /. 9.4.2 EPS location update type./
    DE_SGSAP_GLOBAL_CN_ID,                          /. 9.4.4 Global CN-Id./

    DE_SGSAP_UDEF_11,                               /. Undefined ./
    DE_SGSAP_UDEF_12,                               /. Undefined ./

    DE_SGSAP_MID,                                   /. 9.4.14 Mobile identity./
    DE_SGSAP_REJ_CAUSE,                             /. 9.4.16 Reject cause ./
    DE_SGSAP_IMSI_DET_EPS,                          /. 9.4.7 IMSI detach from EPS service type ./
    DE_SGSAP_IMSI_DET_NON_EPS,                      /. 9.4.8 IMSI detach from non-EPS service type ./

    DE_SGSAP_IMEISV,                                /. 9.4.5 IMEISV ./
    DE_SGSAP_NAS_MSG_CONTAINER,                     /. 9.4.15 NAS message container./
    DE_SGSAP_MM_INFO,                               /. 9.4.12 MM information./

    DE_SGSAP_UDEF_20,                               /. Undefined ./
    DE_SGSAP_UDEF_21,                               /. Undefined ./
    DE_SGSAP_UDEF_22,                               /. Undefined ./

    DE_SGSAP_ERR_MSG,                               /. 9.4.3 Erroneous message./
    DE_SGSAP_CLI,                                   /. 9.4.1 CLI ./
    DE_SGSAP_LCS_CLIENT_ID,                         /. 9.4.9 LCS client identity ./
    DE_SGSAP_LCS_INDIC,                             /. 9.4.10 LCS indicator ./
    DE_SGSAP_SS_CODE,                               /. 9.4.19 SS code ./
    DE_SGSAP_SERV_INDIC,                            /. 9.4.17 Service indicator ./
    DE_SGSAP_UE_TZ,                                 /. 9.4.21b UE Time Zone ./
    DE_SGSAP_MSC_2,                                 /. 9.4.14a Mobile Station Classmark 2 ./
    DE_SGSAP_TAID,                                  /. 9.4.21a Tracking Area Identity ./
    DE_SGSAP_ECGI,                                  /. 9.4.3a E-UTRAN Cell Global Identity ./
    DE_SGSAP_UE_EMM_MODE,                           /. 9.4.21c UE EMM mode./
    DE_SGSAP_ADD_PAGING_IND,                        /. 9.4.25 Additional paging indicators ./
    DE_SGSAP_TMSI_BASED_NRI_CONT,                   /. 9.4.26 TMSI based NRI container ./
    DE_SGSAP_SELECTED_CS_DMN_OP,                    /. 9.4.27 Selected CS domain operator ./

    DE_SGAP_NONE                            /. NONE ./
}
sgsap_elem_idx_t;
#endif /* 0 */

uint16_t (* const sgsap_elem_fcn[])(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len, char *add_string, int string_len) = {
    NULL/*DE_SGSAP_IMSI*/,                                  /* 9.4.6 IMSI*/
    de_sgsap_vlr_name,                                      /* 9.4.22 VLR name*/
    NULL/*DE_SGSAP_TMSI*/,                                  /* 9.4.20 TMSI */
    NULL/*DE_SGSAP_LOC_AREA_ID*/,                           /* 9.4.11 Location area identifier */
    NULL/*DE_SGSAP_CH_NEEDED*/,                             /* 9.4.23 Channel Needed */
    NULL/*DE_SGSAP_EMLPP_PRIO*/,                            /* 9.4.24 eMLPP Priority*/
    NULL/*DE_SGSAP_TMSI_STATUS*/,                           /* 9.4.21 TMSI status */
    de_sgsap_sgs_cause,                                     /* 9.4.18 SGs cause*/
    de_sgsap_mme_name,                                      /* 9.4.13 MME name*/
    de_sgsap_eps_loc_upd_type,                              /* 9.4.2 EPS location update type*/
    de_sgsap_g_cn_id,                                       /* 9.4.4 Global CN-Id*/

    NULL/*DE_SGSAP_UDEF_11*/,                               /* Undefined */
    NULL/*DE_SGSAP_UDEF_12*/,                               /* Undefined */

    NULL/*DE_SGSAP_MID*/,                                   /* 9.4.14 Mobile identity*/
    NULL/*DE_SGSAP_REJ_CAUSE*/,                             /* 9.4.16 Reject cause */
    de_sgsap_imsi_det_eps,                                  /* 9.4.7 IMSI detach from EPS service type */
    de_sgsap_imsi_det_non_eps,                              /* 9.4.8 IMSI detach from non-EPS service type */

    de_sgsap_imeisv,                                        /* 9.4.5 IMEISV */
    de_sgsap_nas_msg_container,                             /* 9.4.15 NAS message container*/
    de_sgsap_mm_info,                                       /* 9.4.12 MM information*/

    NULL/*DE_SGSAP_UDEF_20*/,                               /* Undefined */
    NULL/*DE_SGSAP_UDEF_21*/,                               /* Undefined */
    NULL/*DE_SGSAP_UDEF_22*/,                               /* Undefined */

    de_sgsap_err_msg,                                       /* 9.4.3 Erroneous message*/
    NULL/*DE_SGSAP_CLI*/,                                   /* 9.4.1 CLI */
    NULL/*DE_SGSAP_LCS_CLIENT_ID*/,                         /* 9.4.9 LCS client identity */
    de_sgsap_lcs_indic,                                     /* 9.4.10 LCS indicator */
    NULL/*DE_SGSAP_SS_CODE*/,                               /* 9.4.19 SS code */
    de_sgsap_serv_indic,                                    /* 9.4.17 Service indicator */
    NULL/*DE_SGSAP_UE_TZ*/,                                 /* 9.4.21b UE Time Zone */
    NULL/*DE_SGSAP_MSC_2*/,                                 /* 9.4.14a Mobile Station Classmark 2 */
    NULL/*DE_SGSAP_TAID*/,                                  /* 9.4.21a Tracking Area Identity */
    de_sgsap_ecgi,                                          /* 9.4.3a E-UTRAN Cell Global Identity */
    de_sgsap_ue_emm_mode,                                   /* 9.4.21c UE EMM mode*/
    de_sgsap_add_paging_ind,                                /* 9.4.25 Additional paging indicators */
    NULL/*DE_SGSAP_TMSI_BASED_NRI_CONT */,                  /* 9.4.26 TMSI based NRI container (Reuse GSM_A_PDU_TYPE_GM, DE_NET_RES_ID_CONT */
    de_sgsap_selected_cs_dmn_op,                            /* 9.4.27 Selected CS domain operator */
    NULL,   /* NONE */
};

/* MESSAGE FUNCTIONS */

/*
 * 8.1  SGsAP-ALERT-ACK message
 */
static void
sgsap_alert_ack(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.2  SGsAP-ALERT-REJECT message
 */
static void
sgsap_alert_rej(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* SGs Cause    SGs cause  9.4.18   M   TLV 3 */
    ELEM_MAND_TLV(0x08, SGSAP_PDU_TYPE, DE_SGSAP_SGS_CAUSE, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.3  SGsAP-ALERT-REQUEST message
 */
static void
sgsap_alert_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.4  SGsAP-DOWNLINK-UNITDATA message
 */
static void
sgsap_dl_unitdata(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;


    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* NAS message container    NAS message container 9.4.15    M   TLV 4-253 */
    ELEM_MAND_TLV(0x16, SGSAP_PDU_TYPE, DE_SGSAP_NAS_MSG_CONTAINER, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.5  SGsAP-EPS-DETACH-ACK message
 */

static void
sgsap_eps_det_ack(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 8.6  SGsAP-EPS-DETACH-INDICATION message
 */

static void
sgsap_eps_det_ind(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* MME name MME name 9.4.13 M   TLV 57 */
    ELEM_MAND_TLV(0x09, SGSAP_PDU_TYPE, DE_SGSAP_MME_NAME, NULL, ei_sgsap_missing_mandatory_element);
    /* IMSI detach from EPS service type    IMSI detach from EPS service type 9.4.7 M   TLV 3 */
    ELEM_MAND_TLV(0x10, SGSAP_PDU_TYPE, DE_SGSAP_IMSI_DET_EPS, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.7  SGsAP-IMSI-DETACH-ACK message
 */
static void
sgsap_imsi_det_ack(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 8.8  SGsAP-IMSI-DETACH-INDICATION message
 */
static void
sgsap_imsi_det_ind(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* MME name MME name 9.4.13 M   TLV 57 */
    ELEM_MAND_TLV(0x09, SGSAP_PDU_TYPE, DE_SGSAP_MME_NAME, NULL, ei_sgsap_missing_mandatory_element);
    /* IMSI Detach from non-EPS service type    IMSI detach from non-EPS service type 9.4.8 M   TLV 3 */
    ELEM_MAND_TLV(0x11, SGSAP_PDU_TYPE, DE_SGSAP_IMSI_DET_NON_EPS, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.9  SGsAP-LOCATION-UPDATE-ACCEPT message
 */
static void
sgsap_imsi_loc_update_acc(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* Location area identifier Location area identifier 9.4.11 M   TLV 7 */
    ELEM_MAND_TLV(0x04, GSM_A_PDU_TYPE_COMMON, DE_LAI, NULL, ei_sgsap_missing_mandatory_element);
    /* New TMSI, or IMSI    Mobile identity 9.4.14  O   TLV 6-10 */
    ELEM_OPT_TLV(0x0e, GSM_A_PDU_TYPE_COMMON, DE_MID, " - New TMSI, or IMSI");

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.10 SGsAP-LOCATION-UPDATE-REJECT message
 */
static void
sgsap_imsi_loc_update_rej(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* Reject cause Reject cause 9.4.16 M   TLV 3 */
    ELEM_MAND_TLV(0x0f, GSM_A_PDU_TYPE_DTAP, DE_REJ_CAUSE, NULL, ei_sgsap_missing_mandatory_element);
    /* Location area identifier Location area identifier 9.4.11 O   TLV 7 */
    ELEM_OPT_TLV(0x04, GSM_A_PDU_TYPE_COMMON, DE_LAI, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.11 SGsAP-LOCATION-UPDATE-REQUEST message
 */

static void
sgsap_imsi_loc_update_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* MME name MME name 9.4.13 M   TLV 57 */
    ELEM_MAND_TLV(0x09, SGSAP_PDU_TYPE, DE_SGSAP_MME_NAME, NULL, ei_sgsap_missing_mandatory_element);
    /* EPS location update type EPS location update type 9.4.2  M   TLV 3 */
    ELEM_MAND_TLV(0x0a, SGSAP_PDU_TYPE, DE_SGSAP_EPS_LOC_UPD_TYPE, NULL, ei_sgsap_missing_mandatory_element);
    /* New location area identifier Location area identifier 9.4.11 M   TLV 7 */
    ELEM_MAND_TLV(0x04, GSM_A_PDU_TYPE_COMMON, DE_LAI, NULL, ei_sgsap_missing_mandatory_element);
    /* Old location area identifier Location area identifier 9.4.11 O   TLV 7 */
    ELEM_OPT_TLV(0x04, GSM_A_PDU_TYPE_COMMON, DE_LAI, " - Old location area identifier");
    /* TMSI status  TMSI status 9.4.21  O   TLV 3 */
    ELEM_OPT_TLV( 0x07 , GSM_A_PDU_TYPE_GM, DE_TMSI_STAT , NULL );
    /* IMEISV   IMEISV 9.4.5    O   TLV 10 */
    ELEM_OPT_TLV(0x15, SGSAP_PDU_TYPE, DE_SGSAP_IMEISV, NULL);
    /* TAI Tracking Area Identity 9.4.21a O TLV 7 */
    ELEM_OPT_TLV(0x23, NAS_PDU_TYPE_EMM, DE_EMM_TRAC_AREA_ID, NULL);
    /* E-CGI E-UTRAN Cell Global Identity 9.4.3a O TLV 9 */
    ELEM_OPT_TLV(0x24, SGSAP_PDU_TYPE, DE_SGSAP_ECGI, NULL);
    /* TMSI based NRI container TMSI based NRI container 9.4.26 O TLV 4 */
    ELEM_OPT_TLV(0x27, GSM_A_PDU_TYPE_GM, DE_NET_RES_ID_CONT, " - TMSI based NRI container");
    /* Selected CS domain operator Selected CS domain operator 9.4.27 O TLV 5 */
    ELEM_OPT_TLV(0x28, SGSAP_PDU_TYPE, DE_SGSAP_SELECTED_CS_DMN_OP, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.12 SGsAP-MM-INFORMATION-REQUEST
 */
static void
sgsap_mm_info_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* MM information   MM information 9.4.12   M   TLV 3-n */
    ELEM_MAND_TLV(0x17, SGSAP_PDU_TYPE, DE_SGSAP_MM_INFO, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.13 SGsAP-PAGING-REJECT message
 */
static void
sgsap_paging_rej(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* SGs Cause    SGs Cause 9.4.18    M   TLV 3 */
    ELEM_MAND_TLV(0x08, SGSAP_PDU_TYPE, DE_SGSAP_SGS_CAUSE, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 8.14 SGsAP-PAGING-REQUEST message
 */
static void
sgsap_paging_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* VLR name VLR name 9.4.22 M   TLV 3-n */
    ELEM_MAND_TLV(0x02, SGSAP_PDU_TYPE, DE_SGSAP_VLR_NAME, NULL, ei_sgsap_missing_mandatory_element);
    /* Service indicator    Service indicator 9.4.17    M   TLV 3 */
    ELEM_MAND_TLV(0x20, SGSAP_PDU_TYPE, DE_SGSAP_SERV_INDIC, NULL, ei_sgsap_missing_mandatory_element);
    /* TMSI TMSI 9.4.20 O   TLV 6 */
    ELEM_OPT_TLV(0x03, GSM_A_PDU_TYPE_BSSMAP, BE_TMSI, NULL);
    /* CLI  CLI 9.4.1   O   TLV 3-14 */
    ELEM_OPT_TLV(0x1c, GSM_A_PDU_TYPE_DTAP, DE_CLG_PARTY_BCD_NUM, " - CLI");
    /* Location area identifier Location area identifier 9.4.11 O   TLV 7 */
    ELEM_OPT_TLV(0x04, GSM_A_PDU_TYPE_COMMON, DE_LAI, NULL);
    /* Global CN-Id Global CN-Id 9.4.4  O   TLV 7 */
    ELEM_OPT_TLV(0x0b, SGSAP_PDU_TYPE, DE_SGSAP_GLOBAL_CN_ID, NULL);
    /* SS code  SS code 9.4.19  O   TLV 3 */
    ELEM_OPT_TLV(0x1f, NAS_PDU_TYPE_EMM, DE_EMM_SS_CODE, NULL);
    /* LCS indicator    LCS indicator 9.4.10    O   TLV 3 */
    ELEM_OPT_TLV(0x1e, SGSAP_PDU_TYPE, DE_SGSAP_LCS_INDIC, NULL);
    /* LCS client identity  LCS client identity 9.4.9   O   TLV 3-n */
    ELEM_OPT_TLV(0x1d, NAS_PDU_TYPE_EMM, DE_EMM_LCS_CLIENT_ID, NULL);
    /* Channel needed   Channel needed 9.4.23   O   TLV 3 */
    ELEM_OPT_TLV(0x05, GSM_A_PDU_TYPE_BSSMAP, BE_CHAN_NEEDED, NULL);
    /* eMLPP Priority   eMLPP Priority 9.4.24   O   TLV 3 */
    ELEM_OPT_TLV(0x06, GSM_A_PDU_TYPE_BSSMAP, BE_EMLPP_PRIO, NULL);
    /* Additional paging indicators Additional paging indicators 9.4.25 O TLV 3 */
    ELEM_OPT_TLV(0x26, SGSAP_PDU_TYPE, DE_SGSAP_ADD_PAGING_IND, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 8.15 SGsAP-RESET-ACK message
 */
static void
sgsap_reset_ack(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* MME name MME name 9.4.13 C   TLV 57 */
    ELEM_OPT_TLV(0x09, SGSAP_PDU_TYPE, DE_SGSAP_MME_NAME, NULL);
    /* VLR name VLR name 9.4.22 C   TLV 3-n */
    ELEM_OPT_TLV(0x02, SGSAP_PDU_TYPE, DE_SGSAP_VLR_NAME, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.16 SGsAP-RESET-INDICATION message
 */
static void
sgsap_reset_ind(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* MME name MME name 9.4.13 C   TLV 57 */
    ELEM_OPT_TLV(0x09, SGSAP_PDU_TYPE, DE_SGSAP_MME_NAME, NULL);
    /* VLR name VLR name 9.4.22 C   TLV 3-n */
    ELEM_OPT_TLV(0x02, SGSAP_PDU_TYPE, DE_SGSAP_VLR_NAME, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 8.17 SGsAP-SERVICE-REQUEST message
 */
static void
sgsap_service_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /*IMSI  IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* Service indicator    Service indicator 9.4.17    M   TLV 3 */
    ELEM_MAND_TLV(0x20, SGSAP_PDU_TYPE, DE_SGSAP_SERV_INDIC, NULL, ei_sgsap_missing_mandatory_element);
    /* IMEISV   IMEISV 9.4.5    O   TLV 10 */
    ELEM_OPT_TLV(0x15, SGSAP_PDU_TYPE, DE_SGSAP_IMEISV, NULL);
    /* UE Time Zone UE Time Zone 9.4.21b    O   TLV 3 */
    ELEM_OPT_TLV(0x21, GSM_A_PDU_TYPE_DTAP, DE_TIME_ZONE, " - UE Time Zone");
    /* Mobile Station Classmark 2   Mobile Station Classmark 2 9.4.14a  O   TLV 5 */
    ELEM_OPT_TLV(0x22 , GSM_A_PDU_TYPE_COMMON, DE_MS_CM_2, NULL);
    /* TAI  Tracking Area Identity 9.4.21a  O   TLV 7 */
    ELEM_OPT_TLV(0x23, NAS_PDU_TYPE_EMM, DE_EMM_TRAC_AREA_ID, NULL);
    /* E-CGI    E-UTRAN Cell Global Identity 9.4.3a O   TLV 9 */
    ELEM_OPT_TLV(0x24, SGSAP_PDU_TYPE, DE_SGSAP_ECGI, NULL);
    /* UE EMM Mode  UE EMM mode 9.4.21c O   TLV 3 */
    ELEM_OPT_TLV(0x25, SGSAP_PDU_TYPE, DE_SGSAP_UE_EMM_MODE, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.18 SGsAP-STATUS message
 */
static void
sgsap_status(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  O   TLV 6-10 */
    ELEM_OPT_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL);
    /* SGs cause    SGs cause 9.4.18    M   TLV 3 */
    ELEM_MAND_TLV(0x08, SGSAP_PDU_TYPE, DE_SGSAP_SGS_CAUSE, NULL, ei_sgsap_missing_mandatory_element);
    /* Erroneous message    Erroneous message 9.4.3 M   TLV 3-n */
    ELEM_OPT_TLV(0x1b, SGSAP_PDU_TYPE, DE_SGSAP_ERR_MSG, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.19 SGsAP-TMSI-REALLOCATION-COMPLETE message
 */
static void
sgsap_tmsi_realloc_comp(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /*IMSI  IMSI 9.4.6  M   TLV 6-10  */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.20 SGsAP-UE-ACTIVITY-INDICATION message
 */
static void
sgsap_ue_act_ind(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.21 SGsAP-UE-UNREACHABLE message
 */
static void
sgsap_ue_unreachable(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;


    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* SGs cause    SGs cause 9.4.18    M   TLV 3 */
    ELEM_MAND_TLV(0x08, SGSAP_PDU_TYPE, DE_SGSAP_SGS_CAUSE, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 8.22 SGsAP-UPLINK-UNITDATA message
 */
static void
sgsap_ue_ul_unitdata(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* NAS message container    NAS message container 9.4.15    M   TLV 4-253 */
    ELEM_MAND_TLV(0x16, SGSAP_PDU_TYPE, DE_SGSAP_NAS_MSG_CONTAINER, NULL, ei_sgsap_missing_mandatory_element);
    /* IMEISV   IMEISV 9.4.5    O   TLV 10 */
    ELEM_OPT_TLV(0x15, SGSAP_PDU_TYPE, DE_SGSAP_IMEISV, NULL);
    /* UE Time Zone UE Time Zone 9.4.21b    O   TLV 3 */
    ELEM_OPT_TLV(0x21, GSM_A_PDU_TYPE_DTAP, DE_TIME_ZONE, " - UE Time Zone");
    /* Mobile Station Classmark 2   Mobile Station Classmark 2 9.4.14a  O   TLV 5 */
    ELEM_OPT_TLV(0x22 , GSM_A_PDU_TYPE_COMMON, DE_MS_CM_2, NULL);
    /* TAI  Tracking Area Identity 9.4.21a  O   TLV 7 */
    ELEM_OPT_TLV(0x23, NAS_PDU_TYPE_EMM, DE_EMM_TRAC_AREA_ID, NULL);
    /* E-CGI    E-UTRAN Cell Global Identity 9.4.3a O   TLV 9 */
    ELEM_OPT_TLV(0x24, SGSAP_PDU_TYPE, DE_SGSAP_ECGI, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 8.23 SGsAP-RELEASE-REQUEST message
 */
static void
sgsap_release_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* SGs cause    SGs cause 9.4.18    O   TLV 3 */
    ELEM_OPT_TLV(0x08, SGSAP_PDU_TYPE, DE_SGSAP_SGS_CAUSE, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.24 SGsAP-SERVICE-ABORT-REQUEST message
 */
static void
sgsap_service_abort_req(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6  M   TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}

/*
 * 8.25 SGsAP-MO-CSFB-INDICATION message
 */
static void
sgsap_mo_csfb_ind(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len)
{
    uint32_t curr_offset;
    uint32_t consumed;
    unsigned   curr_len;

    curr_offset = offset;
    curr_len    = len;

    /* IMSI IMSI 9.4.6 M TLV 6-10 */
    ELEM_MAND_TLV(0x01, GSM_A_PDU_TYPE_BSSMAP, BE_IMSI, NULL, ei_sgsap_missing_mandatory_element);
    /* TAI Tracking Area Identity 9.4.21a O TLV 7 */
    ELEM_OPT_TLV(0x23, NAS_PDU_TYPE_EMM, DE_EMM_TRAC_AREA_ID, NULL);
    /* E-CGI E-UTRAN Cell Global Identity 9.4.3a O TLV 9 */
    ELEM_OPT_TLV(0x24, SGSAP_PDU_TYPE, DE_SGSAP_ECGI, NULL);

    EXTRANEOUS_DATA_CHECK(curr_len, 0, pinfo, &ei_sgsap_extraneous_data);
}
/*
 * 9.2  Message type
 */
static const value_string sgsap_msg_strings[] = {
    { 0x01, "SGsAP-PAGING-REQUEST"},                /*  8.14 */
    { 0x02, "SGsAP-PAGING-REJECT"},                 /*  8.13 */
/*
 * 0 0 0 0 0 0 1 1
 * to
 * 0 0 0 0 0 1 0 1
 * Unassigned: treated as an unknown Message type
 */
    { 0x03, "Unassigned"},                          /* 7 */
    { 0x04, "Unassigned"},                          /* 7 */
    { 0x05, "Unassigned"},                          /* 7 */

    { 0x06, "SGsAP-SERVICE-REQUEST"},               /* 8.17 */
    { 0x07, "SGsAP-DOWNLINK-UNITDATA"},             /* 8.4 */
    { 0x08, "SGsAP-UPLINK-UNITDATA"},               /* 8.22 */
    { 0x09, "SGsAP-LOCATION-UPDATE-REQUEST"},       /* 8.11 */
    { 0x0a, "SGsAP-LOCATION-UPDATE-ACCEPT"},        /* 8.9 */
    { 0x0b, "SGsAP-LOCATION-UPDATE-REJECT"},        /* 8.10 */
    { 0x0c, "SGsAP-TMSI-REALLOCATION-COMPLETE"},    /* 8.19 */
    { 0x0d, "SGsAP-ALERT-REQUEST"},                 /* 8.3 */
    { 0x0e, "SGsAP-ALERT-ACK"},                     /* 8.1 */
    { 0x0f, "SGsAP-ALERT-REJECT"},                  /* 8.2 */
    { 0x10, "SGsAP-UE-ACTIVITY-INDICATION"},        /* 8.20 */
    { 0x11, "SGsAP-EPS-DETACH-INDICATION"},         /* 8.6 */
    { 0x12, "SGsAP-EPS-DETACH-ACK"},                /* 8.5 */
    { 0x13, "SGsAP-IMSI-DETACH-INDICATION"},        /* 8.8 */
    { 0x14, "SGsAP-IMSI-DETACH-ACK"},               /* 8.7 */
    { 0x15, "SGsAP-RESET-INDICATION"},              /* 8.16 */
    { 0x16, "SGsAP-RESET-ACK"},                     /* 8.15 */
    { 0x17, "SGsAP-SERVICE-ABORT-REQUEST"},         /* 8.24 */
    { 0x18, "SGsAP-MO-CSFB-INDICATION"},            /* 8.25 */
/*
 * 0 0 0 1 1 0 0 0
 * to
 * 0 0 0 1 1 0 0 1
 * Unassigned: treated as an unknown Message type
 */
    { 0x19, "Unassigned"},

    { 0x1a, "SGsAP-MM-INFORMATION-REQUEST"},        /* 8.12 */
    { 0x1b, "SGsAP-RELEASE-REQUEST"},               /* 8.23 */
/*
 * 0 0 0 1 1 1 0 0  Unassigned: treated as an unknown Message type  7
 */
    { 0x1c, "Unassigned"},                          /* 7 */

    { 0x1d, "SGsAP-STATUS"},                        /* 8.18 */
    { 0x1e, "Unassigned"},                          /* 7 */
    { 0x1f, "SGsAP-UE-UNREACHABLE"},                /* 8.21 */
    { 0,    NULL }
};
static value_string_ext sgsap_msg_strings_ext = VALUE_STRING_EXT_INIT(sgsap_msg_strings);

#define NUM_SGSAP_MSG array_length(sgsap_msg_strings)
static int ett_sgsap_msg[NUM_SGSAP_MSG];
static void (* const sgsap_msg_fcn[])(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo _U_, uint32_t offset, unsigned len) = {
    sgsap_paging_req,           /* 0x01,    "SGsAP-PAGING-REQUEST"  8.14 */
    sgsap_paging_rej,           /* 0x02,    "SGsAP-PAGING-REJECT"   8.13 */
/*
 * 0 0 0 0 0 0 1 1
 * to
 * 0 0 0 0 0 1 0 1
 * Unassigned: treated as an unknown Message type
 */
    NULL,                           /* 0x03,    "Unassigned" 7 */
    NULL,                           /* 0x04,    "Unassigned" 7 */
    NULL,                           /* 0x05,    "Unassigned" 7 */

    sgsap_service_req,              /* 0x06,    "SGsAP-SERVICE-REQUEST" 8.17 */
    sgsap_dl_unitdata,              /* 0x07,    "SGsAP-DOWNLINK-UNITDATA" 8.4 */
    sgsap_ue_ul_unitdata,           /* 0x08,    "SGsAP-UPLINK-UNITDATA" 8.22 */
    sgsap_imsi_loc_update_req,      /* 0x09,    "SGsAP-LOCATION-UPDATE-REQUEST" 8.11 */
    sgsap_imsi_loc_update_acc,      /* 0x0a,    "SGsAP-LOCATION-UPDATE-ACCEPT" 8.9 */
    sgsap_imsi_loc_update_rej,      /* 0x0b,    "SGsAP-LOCATION-UPDATE-REJECT" 8.10 */
    sgsap_tmsi_realloc_comp,        /* 0x0c,    "SGsAP-TMSI-REALLOCATION-COMPLETE"  8.19 */
    sgsap_alert_req,                /* 0x0d,    "SGsAP-ALERT-REQUEST" 8.3 */
    sgsap_alert_ack,                /* 0x0e,    "SGsAP-ALERT-ACK" 8.1 */
    sgsap_alert_rej,                /* 0x0f,    "SGsAP-ALERT-REJECT" 8.2 */
    sgsap_ue_act_ind,               /* 0x10,    "SGsAP-UE-ACTIVITY-INDICATION" 8.20 */
    sgsap_eps_det_ind,              /* 0x11,    "SGsAP-EPS-DETACH-INDICATION" 8.6 */
    sgsap_eps_det_ack,              /* 0x12,    "SGsAP-EPS-DETACH-ACK" 8.5 */
    sgsap_imsi_det_ind,             /* 0x13,    "SGsAP-IMSI-DETACH-INDICATION" 8.8 */
    sgsap_imsi_det_ack,             /* 0x14,    "SGsAP-IMSI-DETACH-ACK" 8.7 */
    sgsap_reset_ind,                /* 0x15,    "SGsAP-RESET-INDICATION" 8.16 */
    sgsap_reset_ack,                /* 0x16,    "SGsAP-RESET-ACK" 8.15 */
    sgsap_service_abort_req,        /* 0x17,    "SGsAP-SERVICE-ABORT-REQUEST" 8.24 */
    sgsap_mo_csfb_ind,              /* 0x18,    "SGsAP-MO-CSFB-INDICATION" 8.25 */
/*
 * 0 0 0 1 1 0 0 1
 * to
 * 0 0 0 1 1 0 0 1
 * Unassigned: treated as an unknown Message type
 */
    NULL,                           /* 0x19,    "Unassigned" */

    sgsap_mm_info_req,              /* 0x1a,    "SGsAP-MM-INFORMATION-REQUEST" 8.12 */
    sgsap_release_req,              /* 0x1b,    "SGsAP-RELEASE-REQUEST" 8.23 */
/*
 * 0 0 0 1 1 1 0 0  Unassigned: treated as an unknown Message type  7
 */
    NULL,                           /* 0x1c,    "Unassigned" */

    sgsap_status,                   /* 0x1d,    "SGsAP-STATUS" 8.18 */
    NULL,                           /* 0x1e,    "Unassigned" */
    sgsap_ue_unreachable,           /* 0x1f,    "SGsAP-UE-UNREACHABLE" 8.21 */

    NULL,   /* NONE */
};

static void get_sgsap_msg_params(uint8_t oct, const char **msg_str, int *ett_tree, int *hf_idx, msg_fcn *msg_fcn_p)
{
    int             idx;

    *msg_str   = try_val_to_str_idx_ext((uint32_t) (oct & 0xff), &sgsap_msg_strings_ext, &idx);
    *hf_idx    = hf_sgsap_msg_type;
    if (*msg_str != NULL) {
        *ett_tree  = ett_sgsap_msg[idx];
        *msg_fcn_p = sgsap_msg_fcn[idx];
    }

    return;
}


static int
dissect_sgsap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    proto_item      *item;
    proto_tree      *sgsap_tree;
    int              offset = 0;
    uint32_t         len;
    const char      *msg_str;
    int              ett_tree;
    int              hf_idx;
    void            (*msg_fcn_p)(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, uint32_t offset, unsigned len);
    uint8_t         oct;

    len = tvb_reported_length(tvb);

    /* Make entry in the Protocol column on summary display */
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "SGSAP");

    item = proto_tree_add_item(tree, proto_sgsap, tvb, 0, -1, ENC_NA);
    sgsap_tree = proto_item_add_subtree(item, ett_sgsap);

    /* Message type IE*/
    oct       = tvb_get_uint8(tvb, offset);
    msg_fcn_p = NULL;
    ett_tree  = -1;
    hf_idx    = -1;
    msg_str   = NULL;

    get_sgsap_msg_params(oct, &msg_str, &ett_tree, &hf_idx, &msg_fcn_p);

    if (msg_str) {
        col_add_str(pinfo->cinfo, COL_INFO, msg_str);
    }else{
        proto_tree_add_item(tree, hf_sgsap_unknown_msg, tvb, offset, 1, ENC_BIG_ENDIAN);
        return tvb_captured_length(tvb);
    }

    /*
     * Add SGSAP message name
     */
    proto_tree_add_item(sgsap_tree, hf_idx, tvb, offset, 1, ENC_BIG_ENDIAN);
    offset++;


    /*
     * decode elements
     */
    if (msg_fcn_p == NULL)
    {
        proto_tree_add_item(sgsap_tree, hf_sgsap_message_elements, tvb, offset, len - offset, ENC_NA);
    }
    else
    {
        (*msg_fcn_p)(tvb, sgsap_tree, pinfo, offset, len - offset);
    }

    return tvb_captured_length(tvb);
}



void proto_register_sgsap(void) {
    unsigned     i;
    unsigned     last_offset;

    /* List of fields */

  static hf_register_info hf[] = {
    { &hf_sgsap_msg_type,
        { "SGSAP Message Type",    "sgsap.msg_type",
        FT_UINT8, BASE_HEX|BASE_EXT_STRING, &sgsap_msg_strings_ext, 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_elem_id,
        { "Element ID",    "sgsap.elem_id",
        FT_UINT8, BASE_HEX, NULL, 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_eps_location_update_type,
        { "EPS location update type",    "sgsap.eps_location_update_type",
        FT_UINT8, BASE_DEC, VALS(sgsap_eps_location_update_type_values), 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_service_indicator_value,
        { "Service indicator",    "sgsap.service_indicator",
        FT_UINT8, BASE_DEC, VALS(sgsap_service_indicator_values), 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_sgs_cause,
        { "SGs cause",    "sgsap.sgs_cause",
        FT_UINT8, BASE_DEC|BASE_EXT_STRING, &sgsap_sgs_cause_values_ext, 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_ue_emm_mode,
        { "UE EMM mode",    "sgsap.ue_emm_mode",
        FT_UINT8, BASE_DEC, VALS(sgsap_ue_emm_mode_values), 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_eci,
        {"ECI (E-UTRAN Cell Identifier)", "sgsap.eci",
        FT_UINT32, BASE_DEC, NULL, 0x0fffffff,
        NULL, HFILL}
    },
    { &hf_sgsap_cn_id,
        {"CN_ID", "sgsap.cn_id",
        FT_UINT16, BASE_DEC, NULL, 0x0,
        NULL, HFILL}
    },
    { &hf_sgsap_imsi_det_eps,
        { "IMSI detach from EPS service type",    "sgsap.imsi_det_eps",
        FT_UINT8, BASE_DEC, VALS(sgsap_imsi_det_from_eps_serv_type_values), 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_imsi_det_non_eps,
        { "IMSI detach from non-EPS service type",    "sgsap.imsi_det_non_eps",
        FT_UINT8, BASE_DEC, VALS(sgsap_imsi_det_from_non_eps_serv_type_values), 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_lcs_indic,
        { "LCS indicator",    "sgsap.lcs_indicator",
        FT_UINT8, BASE_DEC, VALS(sgsap_lcs_indic_values), 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_mme_name,
        {"MME name", "sgsap.mme_name",
        FT_STRING, BASE_NONE, NULL, 0x0,
        NULL, HFILL}
    },
    { &hf_sgsap_vlr_name,
        {"VLR name", "sgsap.vlr_name",
        FT_STRING, BASE_NONE, NULL, 0x0,
        NULL, HFILL}
    },
    { &hf_sgsap_imeisv,
        {"IMEISV", "sgsap.imeisv",
        FT_STRING, BASE_NONE, NULL, 0x0,
        NULL, HFILL}
    },
    { &hf_sgsap_unknown_msg,
        { "Unknown message",    "sgsap.unknown_msg",
        FT_UINT8, BASE_HEX, NULL, 0x0,
        NULL, HFILL }
    },
    { &hf_sgsap_message_elements,
        {"Message Elements", "sgsap.message_elements",
        FT_BYTES, BASE_NONE, NULL, 0x0,
        NULL, HFILL}
    },
    { &hf_sgsap_csri,
        {"CS restoration indicator (CSRI)", "sgsap.csri",
        FT_BOOLEAN, 8, TFS(&tfs_set_notset), 0x01,
        NULL, HFILL }
    },
    { &hf_sgsap_sel_cs_dmn_op,
        { "Selected CS domain operator", "sgsap.sel_cs_dmn_op",
        FT_BYTES, BASE_NONE, NULL, 0x0,
        NULL, HFILL }
    },
  };

    static ei_register_info ei[] = {
        { &ei_sgsap_extraneous_data, { "sgsap.extraneous_data", PI_PROTOCOL, PI_NOTE, "Extraneous Data, dissector bug or later version spec (report to wireshark.org)", EXPFILL }},
        { &ei_sgsap_missing_mandatory_element, { "sgsap.missing_mandatory_element", PI_PROTOCOL, PI_WARN, "Missing Mandatory element, rest of dissection is suspect", EXPFILL }},
    };

   expert_module_t* expert_sgsap;

    /* Setup protocol subtree array */
#define NUM_INDIVIDUAL_ELEMS    2
    int *ett[NUM_INDIVIDUAL_ELEMS +
          NUM_SGSAP_ELEM +
          NUM_SGSAP_MSG];

    ett[0] = &ett_sgsap;
    ett[1] = &ett_sgsap_sel_cs_dmn_op;

    last_offset = NUM_INDIVIDUAL_ELEMS;

    for (i=0; i < NUM_SGSAP_ELEM; i++, last_offset++)
    {
        ett[last_offset] = &ett_sgsap_elem[i];
    }

    for (i=0; i < NUM_SGSAP_MSG; i++, last_offset++)
    {
        ett[last_offset] = &ett_sgsap_msg[i];
    }

    /* Register protocol */
    proto_sgsap = proto_register_protocol("SGs Application Part (SGsAP)", "SGSAP", "sgsap");
    /* Register fields and subtrees */
    proto_register_field_array(proto_sgsap, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_sgsap = expert_register_protocol(proto_sgsap);
    expert_register_field_array(expert_sgsap, ei, array_length(ei));

    /* Register dissector */
    sgsap_handle = register_dissector("sgsap", dissect_sgsap, proto_sgsap);

    /* sgsap_module = prefs_register_protocol(proto_sgsap, NULL); */

}

void
proto_reg_handoff_sgsap(void)
{
    /* The registered SCTP port number for SGsAP is 29118.
     * The payload protocol identifier to be used for SGsAP is 0.
     */
    gsm_a_dtap_handle = find_dissector_add_dependency("gsm_a_dtap", proto_sgsap);
    dissector_add_uint_range_with_preference("sctp.port", SGSAP_SCTP_PORT_RANGE, sgsap_handle);
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */

Coverage Report

Created: 2026-06-30 07:22