iface-modem-location: allow Cell ID only updates

The "Serving System" indications reported via QMI when the device is
moving may contain LAC/TAC+CID updates or just CID updates.

E.g. this one has "CID 3GPP" (0x1e):

  Mon Aug  3 11:22:42 2020 daemon.debug [1567]: [/dev/cdc-wdm0] received
  generic indication (translated)... <<<<<< QMUX: <<<<<<   length  = 33
  <<<<<<   flags   = 0x80 <<<<<<   service = "nas" <<<<<<   client  = 3
  <<<<<< QMI: <<<<<<   flags       = "indication" <<<<<<   transaction =
  4512 <<<<<<   tlv_length  = 21 <<<<<<   message     = "Serving System"
  (0x0024) <<<<<< TLV: <<<<<<   type       = "Serving System" (0x01)
  <<<<<<   length     = 6 <<<<<<   value      = 01:01:01:02:01:08 <<<<<<
    translated = [ registration_state = 'registered' cs_attach_state =
  'attached' ps_attach_state = 'attached' selected_network = '3gpp'
  radio_interfaces = '{ [0] = 'lte '}' ] <<<<<< TLV: <<<<<<   type
  = "Data Service Capability" (0x11) <<<<<<   length     = 2 <<<<<<
  value      = 01:0B <<<<<<   translated = { [0] = 'lte '} <<<<<< TLV:
  <<<<<<   type       = "CID 3GPP" (0x1e) <<<<<<   length     = 4 <<<<<<
    value      = 14:C2:A8:00 <<<<<<   translated = 11059732

And this one has both "CID 3GPP" (0x1e) and "LTE TAC" (0x25):

  Mon Aug  3 11:23:05 2020 daemon.debug [1567]: [/dev/cdc-wdm0] received
  generic indication (translated)... <<<<<< QMUX: <<<<<<   length  = 38
  <<<<<<   flags   = 0x80 <<<<<<   service = "nas" <<<<<<   client  = 3
  <<<<<< QMI: <<<<<<   flags       = "indication" <<<<<<   transaction =
  4513 <<<<<<   tlv_length  = 26 <<<<<<   message     = "Serving System"
  (0x0024) <<<<<< TLV: <<<<<<   type       = "Serving System" (0x01)
  <<<<<<   length     = 6 <<<<<<   value      = 01:01:01:02:01:08 <<<<<<
    translated = [ registration_state = 'registered' cs_attach_state =
  'attached' ps_attach_state = 'attached' selected_network = '3gpp'
  radio_interfaces = '{ [0] = 'lte '}' ] <<<<<< TLV: <<<<<<   type
  = "Data Service Capability" (0x11) <<<<<<   length     = 2 <<<<<<
  value      = 01:0B <<<<<<   translated = { [0] = 'lte '} <<<<<< TLV:
  <<<<<<   type       = "CID 3GPP" (0x1e) <<<<<<   length     = 4 <<<<<<
    value      = 32:36:BC:00 <<<<<<   translated = 12334642 <<<<<< TLV:
  <<<<<<   type       = "LTE TAC" (0x25) <<<<<<   length     = 2 <<<

We should therefore allow changes only in the CID, maintaining
whatever LAC/TAC value we had before.

3 files changed, 25 insertions, 11 deletions

diff --git a/src/mm-broadband-modem-qmi.c b/src/mm-broadband-modem-qmi.c
index 9a1a1e64..8fc5660b 100644
--- a/src/mm-broadband-modem-qmi.c
+++ b/src/mm-broadband-modem-qmi.c
@@ -2668,7 +2668,7 @@ common_process_serving_system_3gpp (MMBroadbandModemQmi *self,
         qmi_indication_nas_serving_system_output_get_cid_3gpp (indication_output, &cid, NULL);
     }
     /* Only update info in the interface if we get something */
-    if (cid && (lac || tac))
+    if (cid || lac || tac)
         mm_iface_modem_3gpp_update_location (MM_IFACE_MODEM_3GPP (self), lac, tac, cid);
 
     /* request to reload operator info explicitly, so that the new
diff --git a/src/mm-iface-modem-3gpp.c b/src/mm-iface-modem-3gpp.c
index 08006709..b933064e 100644
--- a/src/mm-iface-modem-3gpp.c
+++ b/src/mm-iface-modem-3gpp.c
@@ -1359,9 +1359,9 @@ mm_iface_modem_3gpp_update_access_technologies (MMIfaceModem3gpp        *self,
 
 void
 mm_iface_modem_3gpp_update_location (MMIfaceModem3gpp *self,
-                                     gulong location_area_code,
-                                     gulong tracking_area_code,
-                                     gulong cell_id)
+                                     gulong            location_area_code,
+                                     gulong            tracking_area_code,
+                                     gulong            cell_id)
 {
     Private                      *priv;
     MMModem3gppRegistrationState  state;
@@ -1380,7 +1380,7 @@ mm_iface_modem_3gpp_update_location (MMIfaceModem3gpp *self,
      * where we're registering (loading current registration info after a state
      * change to registered), we also allow LAC/CID updates. */
     if (REG_STATE_IS_REGISTERED (state) || priv->reloading_registration_info) {
-        if ((location_area_code > 0 || tracking_area_code > 0) && cell_id > 0)
+        if (location_area_code || tracking_area_code || cell_id)
             mm_iface_modem_location_3gpp_update_lac_tac_ci (MM_IFACE_MODEM_LOCATION (self),
                                                             location_area_code,
                                                             tracking_area_code,
diff --git a/src/mm-iface-modem-location.c b/src/mm-iface-modem-location.c
index ce307ccb..da78a1ff 100644
--- a/src/mm-iface-modem-location.c
+++ b/src/mm-iface-modem-location.c
@@ -396,9 +396,9 @@ mm_iface_modem_location_3gpp_update_mcc_mnc (MMIfaceModemLocation *self,
 
 void
 mm_iface_modem_location_3gpp_update_lac_tac_ci (MMIfaceModemLocation *self,
-                                                gulong location_area_code,
-                                                gulong tracking_area_code,
-                                                gulong cell_id)
+                                                gulong                location_area_code,
+                                                gulong                tracking_area_code,
+                                                gulong                cell_id)
 {
     MmGdbusModemLocation *skeleton;
     LocationContext *ctx;
@@ -414,9 +414,23 @@ mm_iface_modem_location_3gpp_update_lac_tac_ci (MMIfaceModemLocation *self,
         guint changed = 0;
 
         g_assert (ctx->location_3gpp != NULL);
-        changed += mm_location_3gpp_set_location_area_code (ctx->location_3gpp, location_area_code);
-        changed += mm_location_3gpp_set_tracking_area_code (ctx->location_3gpp, tracking_area_code);
-        changed += mm_location_3gpp_set_cell_id            (ctx->location_3gpp, cell_id);
+
+        /* Update LAC if given, and clear TAC unless a TAC is also given */
+        if (location_area_code) {
+            changed += mm_location_3gpp_set_location_area_code (ctx->location_3gpp, location_area_code);
+            if (!tracking_area_code)
+                changed += mm_location_3gpp_set_tracking_area_code (ctx->location_3gpp, 0);
+        }
+        /* Update TAC if given, and clear LAC unless a LAC is also given */
+        if (tracking_area_code) {
+            changed += mm_location_3gpp_set_tracking_area_code (ctx->location_3gpp, tracking_area_code);
+            if (!location_area_code)
+                changed += mm_location_3gpp_set_location_area_code (ctx->location_3gpp, 0);
+        }
+        /* Cell ID only updated if given. It is assumed that if LAC or TAC are given, CID is also given */
+        if (cell_id)
+            changed += mm_location_3gpp_set_cell_id (ctx->location_3gpp, cell_id);
+
         if (changed)
             notify_3gpp_location_update (self, skeleton, ctx->location_3gpp);
     }