libmsc/gsm_04_11.c: accept MT SMS messages over GSUP

Change-Id: I57357982ca0e51f6722c24a4aa1d0fb3e6caef88
Depends-on: (core) Ibe325c64ae2d6c626b232533bb4cbc65fc2b5d71
Depends-on: (OsmoHLR) I0589ff27933e9bca2bcf93b8259004935778db8f
Related Change-Id: (TTCN) I63a25c8366cce0852df6b628365151661a22a25f
Related: OS#3587

3 files changed, 154 insertions, 4 deletions

diff --git a/src/libmsc/gsm_04_08.c b/src/libmsc/gsm_04_08.c
index 7ff868140..686194fc8 100644
--- a/src/libmsc/gsm_04_08.c
+++ b/src/libmsc/gsm_04_08.c
@@ -1810,6 +1810,11 @@ static int msc_vlr_route_gsup_msg(struct vlr_subscr *vsub,
 		DEBUGP(DMSC, "Routed to GSM 04.11 MO handler\n");
 		return gsm411_gsup_mo_handler(vsub, gsup_msg);
 
+	/* GSM 04.11 code implementing MT SMS */
+	case OSMO_GSUP_MSGT_MT_FORWARD_SM_REQUEST:
+		DEBUGP(DMSC, "Routed to GSM 04.11 MT handler\n");
+		return gsm411_gsup_mt_handler(vsub, gsup_msg);
+
 	default:
 		LOGP(DMM, LOGL_ERROR, "No handler found for %s, dropping message...\n",
 			osmo_gsup_message_type_name(gsup_msg->message_type));
diff --git a/src/libmsc/gsm_04_11.c b/src/libmsc/gsm_04_11.c
index 788a0a946..15a92d487 100644
--- a/src/libmsc/gsm_04_11.c
+++ b/src/libmsc/gsm_04_11.c
@@ -158,10 +158,13 @@ static int paging_cb_mmsms_est_req(unsigned int hooknum, unsigned int event,
 		gsm411_smc_recv(&trans->sms.smc_inst,
 			GSM411_MMSMS_REL_IND, NULL, 0);
 
-		/* Notify the SMSqueue and free stored SMS */
-		send_signal(S_SMS_UNKNOWN_ERROR, NULL, sms, event);
-		trans->sms.sms = NULL;
-		sms_free(sms);
+		/* gsm411_send_rp_data() doesn't set trans->sms.sms */
+		if (sms != NULL) {
+			/* Notify the SMSqueue and free stored SMS */
+			send_signal(S_SMS_UNKNOWN_ERROR, NULL, sms, event);
+			trans->sms.sms = NULL;
+			sms_free(sms);
+		}
 
 		/* Destroy this transaction */
 		trans_free(trans);
@@ -794,6 +797,11 @@ static int gsm411_rx_rp_ack(struct gsm_trans *trans,
 	 * successfully received a SMS.  We can now safely mark it as
 	 * transmitted */
 
+	if (trans->net->sms_over_gsup) {
+		/* Forward towards SMSC via GSUP */
+		return gsm411_gsup_mt_fwd_sm_res(trans, rph->msg_ref);
+	}
+
 	if (!sms) {
 		LOGP(DLSMS, LOGL_ERROR, "RX RP-ACK but no sms in transaction?!?\n");
 		return gsm411_send_rp_error(trans, rph->msg_ref,
@@ -830,6 +838,11 @@ static int gsm411_rx_rp_error(struct gsm_trans *trans,
 	     vlr_subscr_name(trans->conn->vsub), cause_len, cause,
 	     get_value_string(gsm411_rp_cause_strs, cause));
 
+	if (trans->net->sms_over_gsup) {
+		/* Forward towards SMSC via GSUP */
+		return gsm411_gsup_mt_fwd_sm_err(trans, rph->msg_ref, cause);
+	}
+
 	if (!sms) {
 		LOGP(DLSMS, LOGL_ERROR,
 			"RX RP-ERR, but no sms in transaction?!?\n");
@@ -1112,6 +1125,42 @@ int gsm411_send_sms(struct gsm_network *net,
 		GSM411_SM_RL_DATA_REQ);
 }
 
+/* Low-level function to send raw RP-DATA to a given subscriber */
+int gsm411_send_rp_data(struct gsm_network *net, struct vlr_subscr *vsub,
+			size_t sm_rp_oa_len, const uint8_t *sm_rp_oa,
+			size_t sm_rp_ud_len, const uint8_t *sm_rp_ud)
+{
+	struct gsm_trans *trans;
+	struct msgb *msg;
+
+	/* Allocate a new transaction for MT SMS */
+	trans = gsm411_alloc_mt_trans(net, vsub);
+	if (!trans)
+		return -ENOMEM;
+
+	/* Allocate a message buffer for to be encoded SMS */
+	msg = gsm411_msgb_alloc();
+	if (!msg) {
+		trans_free(trans);
+		return -ENOMEM;
+	}
+
+	/* Encode SM-RP-OA (SMSC address) */
+	msgb_lv_put(msg, sm_rp_oa_len, sm_rp_oa);
+
+	/* Encode SM-RP-DA (shall be empty, len=0) */
+	msgb_v_put(msg, 0x00);
+
+	/* Encode RP-UD itself (SM TPDU) */
+	msgb_lv_put(msg, sm_rp_ud_len, sm_rp_ud);
+
+	rate_ctr_inc(&net->msc_ctrs->ctr[MSC_CTR_SMS_DELIVERED]);
+
+	return gsm411_rp_sendmsg(&trans->sms.smr_inst, msg,
+		GSM411_MT_RP_DATA_MT, trans->sms.sm_rp_mr,
+		GSM411_SM_RL_DATA_REQ);
+}
+
 /* Entry point for incoming GSM48_PDISC_SMS from abis_rsl.c */
 int gsm0411_rcv_sms(struct ran_conn *conn,
 		    struct msgb *msg)
diff --git a/src/libmsc/gsm_04_11_gsup.c b/src/libmsc/gsm_04_11_gsup.c
index 5c0107245..f2de95f70 100644
--- a/src/libmsc/gsm_04_11_gsup.c
+++ b/src/libmsc/gsm_04_11_gsup.c
@@ -201,3 +201,99 @@ msg_error:
 		msg_name, msg_is_err ? "Err" : "Res");
 	return -EINVAL;
 }
+
+int gsm411_gsup_mt_fwd_sm_res(struct gsm_trans *trans, uint8_t sm_rp_mr)
+{
+	struct osmo_gsup_message gsup_msg;
+
+	/* Associate logging messages with this subscriber */
+	log_set_context(LOG_CTX_VLR_SUBSCR, trans->vsub);
+
+	LOGP(DLSMS, LOGL_DEBUG, "TX MT-forwardSM-Res\n");
+
+	/* Initialize a new GSUP message */
+	gsup_sm_msg_init(&gsup_msg, OSMO_GSUP_MSGT_MT_FORWARD_SM_RESULT,
+		trans->vsub->imsi, &sm_rp_mr);
+
+	return osmo_gsup_client_enc_send(trans->net->vlr->gsup_client, &gsup_msg);
+}
+
+int gsm411_gsup_mt_fwd_sm_err(struct gsm_trans *trans,
+	uint8_t sm_rp_mr, uint8_t cause)
+{
+	struct osmo_gsup_message gsup_msg;
+
+	/* Associate logging messages with this subscriber */
+	log_set_context(LOG_CTX_VLR_SUBSCR, trans->vsub);
+
+	LOGP(DLSMS, LOGL_DEBUG, "TX MT-forwardSM-Err\n");
+
+	/* Initialize a new GSUP message */
+	gsup_sm_msg_init(&gsup_msg, OSMO_GSUP_MSGT_MT_FORWARD_SM_ERROR,
+		trans->vsub->imsi, &sm_rp_mr);
+
+	/* SM-RP-Cause value */
+	gsup_msg.sm_rp_cause = &cause;
+
+	/* TODO: include optional SM-RP-UI field if present */
+	return osmo_gsup_client_enc_send(trans->net->vlr->gsup_client, &gsup_msg);
+}
+
+/* Handles MT SMS (and triggers Paging Request if required) */
+int gsm411_gsup_mt_handler(struct vlr_subscr *vsub,
+	struct osmo_gsup_message *gsup_msg)
+{
+	struct vlr_instance *vlr;
+	struct gsm_network *net;
+	int rc;
+
+	/* Obtain required pointers */
+	vlr = vsub->vlr;
+	net = (struct gsm_network *) vlr->user_ctx;
+
+	/* Associate logging messages with this subscriber */
+	log_set_context(LOG_CTX_VLR_SUBSCR, vsub);
+
+	LOGP(DLSMS, LOGL_DEBUG, "RX MT-forwardSM-Req\n");
+
+	/* Make sure that 'SMS over GSUP' is expected */
+	if (!net->sms_over_gsup) {
+		LOGP(DLSMS, LOGL_NOTICE, "Unexpected MT SMS over GSUP, "
+			"ignoring message...\n");
+		/* TODO: notify sender about that? */
+		return -EIO;
+	}
+
+	/**
+	 * Verify GSUP message
+	 *
+	 * FIXME: SM-RP-MR is not known yet (to be assigned by MSC)
+	 * NOTE: SM-RP-DA is out of our interest
+	 */
+	if (!gsup_msg->sm_rp_mr)
+		goto msg_error;
+	if (!gsup_msg->sm_rp_ui)
+		goto msg_error;
+
+	/* SM-RP-OA shall contain SMSC address */
+	if (gsup_msg->sm_rp_oa_type != OSMO_GSUP_SMS_SM_RP_ODA_SMSC_ADDR)
+		goto msg_error;
+
+	/* Send RP-DATA */
+	rc = gsm411_send_rp_data(net, vsub,
+		gsup_msg->sm_rp_oa_len, gsup_msg->sm_rp_oa,
+		gsup_msg->sm_rp_ui_len, gsup_msg->sm_rp_ui);
+	if (rc) {
+		LOGP(DLSMS, LOGL_NOTICE, "Failed to send MT SMS, "
+			"ignoring MT-forwardSM-Req message...\n");
+		/* TODO: notify sender about that? */
+		return rc;
+	}
+
+	return 0;
+
+msg_error:
+	/* TODO: notify sender about that? */
+	LOGP(DLSMS, LOGL_NOTICE, "RX malformed MT-forwardSM-Req\n");
+	return -EINVAL;
+}