/*! Decode Global Call Reference, 3GPP TS 29.205 Table B 2.1.9.1.
* \param[out] gcr Caller-provided memory to store Global Call Reference
* \param[in] elem IE value to be decoded
* \param[in] len Length of \a elem in bytes
* \returns number of bytes parsed; negative on error */
int osmo_dec_gcr(struct osmo_gcr_parsed *gcr, const uint8_t *elem, uint8_t len)
{
uint16_t parsed = 1; /* account for length byte right away */
if (len < 13)
return -EBADMSG;
gcr->net_len = elem[0];
if (gcr->net_len < 3 || gcr->net_len > 5)
return -EINVAL;
memcpy(gcr->net, elem + parsed, gcr->net_len);
/* +1 for ignored Node ID length field */
parsed += (gcr->net_len + 1);
gcr->node = osmo_load16be(elem + parsed);
parsed += 2;
if (elem[parsed] != 5) /* see Table B 2.1.9.2 */
return -ENOENT;
parsed++;
memcpy(gcr->cr, elem + parsed, 5);
return parsed + 5;
}
/* GSM 08.08 § 3.2.1.19 */
static int bssmap_handle_paging(struct osmo_msc_data *msc,
struct msgb *msg, unsigned int payload_length)
{
struct gsm_subscriber *subscr;
struct tlv_parsed tp;
char mi_string[GSM48_MI_SIZE];
uint32_t tmsi = GSM_RESERVED_TMSI;
unsigned int lac = GSM_LAC_RESERVED_ALL_BTS;
uint8_t data_length;
const uint8_t *data;
uint8_t chan_needed = RSL_CHANNEED_ANY;
tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h + 1, payload_length - 1, 0, 0);
if (!TLVP_PRESENT(&tp, GSM0808_IE_IMSI)) {
LOGP(DMSC, LOGL_ERROR, "Mandatory IMSI not present.\n");
return -1;
} else if ((TLVP_VAL(&tp, GSM0808_IE_IMSI)[0] & GSM_MI_TYPE_MASK) != GSM_MI_TYPE_IMSI) {
LOGP(DMSC, LOGL_ERROR, "Wrong content in the IMSI\n");
return -1;
}
if (!TLVP_PRESENT(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST)) {
LOGP(DMSC, LOGL_ERROR, "Mandatory CELL IDENTIFIER LIST not present.\n");
return -1;
}
if (TLVP_PRESENT(&tp, GSM0808_IE_TMSI) &&
TLVP_LEN(&tp, GSM0808_IE_TMSI) == 4) {
tmsi = ntohl(tlvp_val32_unal(&tp, GSM0808_IE_TMSI));
}
/*
* parse the IMSI
*/
gsm48_mi_to_string(mi_string, sizeof(mi_string),
TLVP_VAL(&tp, GSM0808_IE_IMSI), TLVP_LEN(&tp, GSM0808_IE_IMSI));
/*
* parse the cell identifier list
*/
data_length = TLVP_LEN(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
data = TLVP_VAL(&tp, GSM0808_IE_CELL_IDENTIFIER_LIST);
/*
* Support paging to all network or one BTS at one LAC
*/
if (data_length == 3 && data[0] == CELL_IDENT_LAC) {
lac = osmo_load16be(&data[1]);
} else if (data_length > 1 || (data[0] & 0x0f) != CELL_IDENT_BSS) {
LOGP(DMSC, LOGL_ERROR, "Unsupported Cell Identifier List: %s\n", osmo_hexdump(data, data_length));
return -1;
}
if (TLVP_PRESENT(&tp, GSM0808_IE_CHANNEL_NEEDED) && TLVP_LEN(&tp, GSM0808_IE_CHANNEL_NEEDED) == 1)
chan_needed = TLVP_VAL(&tp, GSM0808_IE_CHANNEL_NEEDED)[0] & 0x03;
if (TLVP_PRESENT(&tp, GSM0808_IE_EMLPP_PRIORITY)) {
LOGP(DMSC, LOGL_ERROR, "eMLPP is not handled\n");
}
subscr = subscr_get_or_create(msc->network->subscr_group, mi_string);
if (!subscr) {
LOGP(DMSC, LOGL_ERROR, "Failed to allocate a subscriber for %s\n", mi_string);
return -1;
}
subscr->lac = lac;
subscr->tmsi = tmsi;
LOGP(DMSC, LOGL_INFO, "Paging request from MSC IMSI: '%s' TMSI: '0x%x/%u' LAC: 0x%x\n", mi_string, tmsi, tmsi, lac);
bsc_grace_paging_request(subscr, chan_needed, msc);
return 0;
}
/*
* Handle the assignment request message.
*
* See §3.2.1.1 for the message type
*/
static int bssmap_handle_assignm_req(struct osmo_bsc_sccp_con *conn,
struct msgb *msg, unsigned int length)
{
struct msgb *resp;
struct osmo_msc_data *msc;
struct tlv_parsed tp;
uint8_t *data;
uint8_t timeslot;
uint8_t multiplex;
enum gsm48_chan_mode chan_mode = GSM48_CMODE_SIGN;
int i, supported, port, full_rate = -1;
if (!conn->conn) {
LOGP(DMSC, LOGL_ERROR, "No lchan/msc_data in cipher mode command.\n");
return -1;
}
tlv_parse(&tp, gsm0808_att_tlvdef(), msg->l4h + 1, length - 1, 0, 0);
if (!TLVP_PRESENT(&tp, GSM0808_IE_CHANNEL_TYPE)) {
LOGP(DMSC, LOGL_ERROR, "Mandatory channel type not present.\n");
goto reject;
}
if (!TLVP_PRESENT(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE)) {
LOGP(DMSC, LOGL_ERROR, "Identity code missing. Audio routing will not work.\n");
goto reject;
}
conn->cic = osmo_load16be(TLVP_VAL(&tp, GSM0808_IE_CIRCUIT_IDENTITY_CODE));
timeslot = conn->cic & 0x1f;
multiplex = (conn->cic & ~0x1f) >> 5;
/*
* Currently we only support a limited subset of all
* possible channel types. The limitation ends by not using
* multi-slot, limiting the channel coding, speech...
*/
if (TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE) < 3) {
LOGP(DMSC, LOGL_ERROR, "ChannelType len !=3 not supported: %d\n",
TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE));
goto reject;
}
/*
* Try to figure out if we support the proposed speech codecs. For
* now we will always pick the full rate codecs.
*/
data = (uint8_t *) TLVP_VAL(&tp, GSM0808_IE_CHANNEL_TYPE);
if ((data[0] & 0xf) != 0x1) {
LOGP(DMSC, LOGL_ERROR, "ChannelType != speech: %d\n", data[0]);
goto reject;
}
/*
* go through the list of preferred codecs of our gsm network
* and try to find it among the permitted codecs. If we found
* it we will send chan_mode to the right mode and break the
* inner loop. The outer loop will exit due chan_mode having
* the correct value.
*/
full_rate = 0;
msc = conn->msc;
for (supported = 0;
chan_mode == GSM48_CMODE_SIGN && supported < msc->audio_length;
++supported) {
int perm_val = audio_support_to_gsm88(msc->audio_support[supported]);
for (i = 2; i < TLVP_LEN(&tp, GSM0808_IE_CHANNEL_TYPE); ++i) {
if ((data[i] & 0x7f) == perm_val) {
chan_mode = gsm88_to_chan_mode(perm_val);
full_rate = (data[i] & 0x4) == 0;
break;
} else if ((data[i] & 0x80) == 0x00) {
break;
}
}
}
if (chan_mode == GSM48_CMODE_SIGN) {
LOGP(DMSC, LOGL_ERROR, "No supported audio type found.\n");
goto reject;
}
/* map it to a MGCP Endpoint and a RTP port */
port = mgcp_timeslot_to_endpoint(multiplex, timeslot);
conn->rtp_port = rtp_calculate_port(port, msc->rtp_base);
return gsm0808_assign_req(conn->conn, chan_mode, full_rate);
reject:
resp = gsm0808_create_assignment_failure(GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE, NULL);
if (!resp) {
LOGP(DMSC, LOGL_ERROR, "Channel allocation failure.\n");
return -1;
}
bsc_queue_for_msc(conn, resp);
return -1;
}
