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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
This commit is contained in:
Mychaela N. Falconia 2023-08-28 18:46:41 +00:00
parent f1158c7719
commit 3bb01d0ef6
3 changed files with 60 additions and 0 deletions
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1
include/osmocom/hlr/hlr_sms.h
View File

@ -30,3 +30,4 @@ void smsc_route_del(struct hlr_smsc_route *rt);
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);

3
src/hlr.c
View File

@ -563,6 +563,9 @@ static int read_cb(struct osmo_gsup_conn *conn, struct msgb *msg)
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));

56
src/hlr_sms.c
View File

@ -219,3 +219,59 @@ void forward_mt_sms(struct osmo_gsup_req *req)
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);
}