SMS over GSUP: handle READY-FOR-SM.req from MSCs
When an MS indicates that it is ready to receive MT SMS, the MSC will
send us a READY-FOR-SM.req message. Handle it by sending copies of
the same message to all connected SMSCs and returning OK result
to the MS that indicates its ready status.
Related: OS#6135
Change-Id: I731545a3a0d0804289e24a7769e13bfd3f645132
diff --git a/include/osmocom/hlr/hlr_sms.h b/include/osmocom/hlr/hlr_sms.h
index b3beea6..0a75b05 100644
--- a/include/osmocom/hlr/hlr_sms.h
+++ b/include/osmocom/hlr/hlr_sms.h
@@ -30,3 +30,4 @@
void forward_mo_sms(struct osmo_gsup_req *req);
void forward_mt_sms(struct osmo_gsup_req *req);
+void rx_ready_for_sm_req(struct osmo_gsup_req *req);
diff --git a/src/hlr.c b/src/hlr.c
index 3d4026a..043189c 100644
--- a/src/hlr.c
+++ b/src/hlr.c
@@ -562,6 +562,9 @@
case OSMO_GSUP_MSGT_MT_FORWARD_SM_REQUEST:
forward_mt_sms(req);
break;
+ case OSMO_GSUP_MSGT_READY_FOR_SM_REQUEST:
+ rx_ready_for_sm_req(req);
+ break;
default:
LOGP(DMAIN, LOGL_DEBUG, "Unhandled GSUP message type %s\n",
osmo_gsup_message_type_name(req->gsup.message_type));
diff --git a/src/hlr_sms.c b/src/hlr_sms.c
index ac4d50d..918d094 100644
--- a/src/hlr_sms.c
+++ b/src/hlr_sms.c
@@ -219,3 +219,59 @@
strlen(subscr.vlr_number) + 1);
osmo_gsup_forward_to_local_peer(req->cb_data, &dest_peer, req, NULL);
}
+
+/***********************************************************************
+ * READY-FOR-SM handling
+ *
+ * An MSC indicates that an MS is ready to receive messages. If one
+ * or more SMSCs have previously tried to send MT SMS to this MS and
+ * failed, we should pass this READY-FOR-SM message to them so they
+ * can resend their queued SMS right away. But which SMSC do we
+ * forward the message to? 3GPP specs call for a complicated system
+ * where the HLR remembers which SMSCs have tried and failed to deliver
+ * MT SMS, and those SMSCs then get notified - but that design is too
+ * much complexity for the current state of Osmocom. So we keep it
+ * simple: we iterate over all configured SMSCs and forward a copy
+ * of the READY-FOR-SM.req message to each.
+ *
+ * Routing of responses is another problem: the MSC that sent
+ * READY-FOR-SM.req expects only one response, and one can even argue
+ * that the operation is a "success" from the perspective of the MS
+ * irrespective of whether each given SMSC handled the notification
+ * successfully or not. Hence our approach: we always return success
+ * to the MS, and when we forward copies of READY-FOR-SM.req to SMSCs,
+ * we list the HLR as the message source - this way SMSC responses
+ * will terminate at this HLR and won't be forwarded to the MSC.
+ ***********************************************************************/
+
+static void forward_req_copy_to_smsc(const struct osmo_gsup_req *req,
+ const struct hlr_smsc *smsc)
+{
+ const char *my_ipa_name = g_hlr->gsup_unit_name.serno;
+ struct osmo_gsup_message forward = req->gsup;
+ struct osmo_ipa_name smsc_ipa_name;
+
+ /* set the source to this HLR */
+ forward.source_name = (const uint8_t *) my_ipa_name;
+ forward.source_name_len = strlen(my_ipa_name) + 1;
+
+ /* send it off */
+ LOG_GSUP_REQ(req, LOGL_INFO, "Forwarding source-reset copy to %s\n",
+ smsc->name);
+ osmo_ipa_name_set(&smsc_ipa_name, (const uint8_t *) smsc->name,
+ strlen(smsc->name) + 1);
+ osmo_gsup_enc_send_to_ipa_name(g_hlr->gs, &smsc_ipa_name, &forward);
+}
+
+void rx_ready_for_sm_req(struct osmo_gsup_req *req)
+{
+ struct hlr_smsc *smsc;
+
+ /* fan request msg out to all SMSCs */
+ llist_for_each_entry(smsc, &g_hlr->smsc_list, list)
+ forward_req_copy_to_smsc(req, smsc);
+
+ /* send OK response to the MSC and the MS */
+ osmo_gsup_req_respond_msgt(req, OSMO_GSUP_MSGT_READY_FOR_SM_RESULT,
+ true);
+}