libmsc: handle delivery ack via SMPP SUBMIT SM / send GSM 03.40 status report

This patch adds gsm340_sms_send_status_report_tpdu() to build a
status-report. Moreover, set sms->report field if we see a SMPP
SUBMIT_SM with Delivery Acknowledgment esm_class, so this identifies
that this is a delivery report.

    MS        GSM 03.40           SMSC       SMPP 3.4               ESME
     |                             |                                |
     |                             |           SUBMIT-SM            |
     |                             |    esm_class = Delivery Ack    |
     |                             |<-------------------------------|
     |                             |         SUBMIT-SM-RESP         |
     |                             |------------------------------->|
     |                             |                                |
     |     SMS-STATUS-REPORT       |                                |
     |<----------------------------|                                |
     |     GSM 04.11 RP-ACK        |                                |
     |---------------------------->|                                |
     |                             |                                |

There is a FIXME message in this patch, that I just copied from
gsm340_gen_sms_deliver_tpdu() since TP-MMS is not supported by OpenBSC.

Change-Id: Ib70e534840308ed315f7add440351e649de3f907

2 files changed, 54 insertions, 2 deletions

diff --git a/openbsc/src/libmsc/gsm_04_11.c b/openbsc/src/libmsc/gsm_04_11.c
index 0edbe0b6c..80c3d779e 100644
--- a/openbsc/src/libmsc/gsm_04_11.c
+++ b/openbsc/src/libmsc/gsm_04_11.c
@@ -277,6 +277,49 @@ static int gsm340_gen_sms_deliver_tpdu(struct msgb *msg, struct gsm_sms *sms)
 	return msg->len - old_msg_len;
 }
 
+/* As defined by GSM 03.40, Section 9.2.2.3. */
+static int gsm340_gen_sms_status_report_tpdu(struct msgb *msg,
+					     struct gsm_sms *sms)
+{
+	unsigned int old_msg_len = msg->len;
+	uint8_t oa_len = 0;
+	uint8_t oa[12];	/* max len per 03.40 */
+	uint8_t *smsp;
+
+	/* generate first octet with masked bits */
+	smsp = msgb_put(msg, 1);
+	/* TP-MTI (message type indicator) */
+	*smsp = GSM340_SMS_STATUS_REP_SC2MS;
+	/* TP-MMS (more messages to send) */
+	if (0 /* FIXME */)
+		*smsp |= 0x04;
+	/* TP-MR (message reference) */
+	smsp = msgb_put(msg, 1);
+	*smsp = sms->msg_ref;
+	/* generate recipient address */
+	oa_len = gsm340_gen_oa_sub(oa, sizeof(oa), &sms->dst);
+	smsp = msgb_put(msg, oa_len);
+	memcpy(smsp, oa, oa_len);
+
+	/* generate TP-SCTS (Service centre timestamp) */
+	smsp = msgb_put(msg, 7);
+	gsm340_gen_scts(smsp, time(NULL));
+
+	/* generate TP-DT (Discharge time, in TP-SCTS format). */
+	smsp = msgb_put(msg, 7);
+	gsm340_gen_scts(smsp, time(NULL));
+
+	/* TP-ST (status) */
+	smsp = msgb_put(msg, 1);
+	/* From GSM 03.40, Section 9.2.3.15, 0x00 means OK. */
+	*smsp = 0x00;
+
+	LOGP(DLSMS, LOGL_INFO, "sending status report for SMS reference %x\n",
+	     sms->msg_ref);
+
+	return msg->len - old_msg_len;
+}
+
 static int sms_route_mt_sms(struct gsm_subscriber_connection *conn,
 			    struct gsm_sms *gsms)
 {
@@ -989,8 +1032,13 @@ int gsm411_send_sms(struct gsm_subscriber_connection *conn, struct gsm_sms *sms)
 	/* obtain a pointer for the rp_ud_len, so we can fill it later */
 	rp_ud_len = (uint8_t *)msgb_put(msg, 1);
 
-	/* generate the 03.40 SMS-DELIVER TPDU */
-	rc = gsm340_gen_sms_deliver_tpdu(msg, sms);
+	if (sms->is_report) {
+		/* generate the 03.40 SMS-STATUS-REPORT TPDU */
+		rc = gsm340_gen_sms_status_report_tpdu(msg, sms);
+	} else {
+		/* generate the 03.40 SMS-DELIVER TPDU */
+		rc = gsm340_gen_sms_deliver_tpdu(msg, sms);
+	}
 	if (rc < 0) {
 		send_signal(S_SMS_UNKNOWN_ERROR, trans, sms, 0);
 		sms_free(sms);
diff --git a/openbsc/src/libmsc/smpp_openbsc.c b/openbsc/src/libmsc/smpp_openbsc.c
index c0aa89bc5..85de04045 100644
--- a/openbsc/src/libmsc/smpp_openbsc.c
+++ b/openbsc/src/libmsc/smpp_openbsc.c
@@ -143,6 +143,10 @@ static int submit_to_sms(struct gsm_sms **psms, struct gsm_network *net,
 	osmo_strlcpy(sms->src.addr, (char *)submit->source_addr,
 		     sizeof(sms->src.addr));
 
+	/* This is a Delivery Acknowledgment. */
+	if (submit->esm_class == 0x08)
+		sms->is_report = true;
+
 	if (submit->esm_class & 0x40)
 		sms->ud_hdr_ind = 1;