broadband-modem: implement default connection monitoring logic

A default implementation to monitor the ongoing connection is provided in the
generic MMBroadbandModem, based on AT+CGACT? to check whether the PDP context
of the connection (identified by the cached cid) is active or not.

This commit also disables the connection monitoring logic in those plugins that
have custom connection methods.

src/mm-bearer-mbim.c

@@ -1375,6 +1375,8 @@ mm_bearer_mbim_class_init (MMBearerMbimClass *klass)
     base_bearer_class->report_connection_status = report_connection_status;
     base_bearer_class->reload_stats = reload_stats;
     base_bearer_class->reload_stats_finish = reload_stats_finish;
+    base_bearer_class->load_connection_status = NULL;
+    base_bearer_class->load_connection_status_finish = NULL;
 
     properties[PROP_SESSION_ID] =
         g_param_spec_uint (MM_BEARER_MBIM_SESSION_ID,

src/mm-bearer-qmi.c

@@ -1674,4 +1674,6 @@ mm_bearer_qmi_class_init (MMBearerQmiClass *klass)
     base_bearer_class->report_connection_status = report_connection_status;
     base_bearer_class->reload_stats = reload_stats;
     base_bearer_class->reload_stats_finish = reload_stats_finish;
+    base_bearer_class->load_connection_status = NULL;
+    base_bearer_class->load_connection_status_finish = NULL;
 }

src/mm-broadband-bearer.c

@@ -1909,6 +1909,99 @@ disconnect (MMBaseBearer *self,
     g_object_unref (modem);
 }
 
+/*****************************************************************************/
+/* Connection status monitoring */
+
+static MMBearerConnectionStatus
+load_connection_status_finish (MMBaseBearer  *bearer,
+                               GAsyncResult  *res,
+                               GError       **error)
+{
+    gssize value;
+
+    value = g_task_propagate_int (G_TASK (res), error);
+    return (value < 0 ? MM_BEARER_CONNECTION_STATUS_UNKNOWN : (MMBearerConnectionStatus) value);
+}
+
+static void
+cgact_periodic_query_ready (MMBaseModem  *modem,
+                            GAsyncResult *res,
+                            GTask        *task)
+{
+    MMBroadbandBearer        *self;
+    const gchar              *response;
+    GError                   *error = NULL;
+    GList                    *pdp_active_list = NULL;
+    GList                    *l;
+    MMBearerConnectionStatus  status = MM_BEARER_CONNECTION_STATUS_UNKNOWN;
+
+    self = MM_BROADBAND_BEARER (g_task_get_source_object (task));
+
+    response = mm_base_modem_at_command_finish (modem, res, &error);
+    if (response)
+        pdp_active_list = mm_3gpp_parse_cgact_read_response (response, &error);
+
+    if (error) {
+        g_assert (!pdp_active_list);
+        g_prefix_error (&error, "Couldn't check current list of active PDP contexts: ");
+        g_task_return_error (task, error);
+        g_object_unref (task);
+        return;
+    }
+
+    for (l = pdp_active_list; l; l = g_list_next (l)) {
+        MM3gppPdpContextActive *pdp_active;
+
+        /* We look for he just assume the first active PDP context found is the one we're
+         * looking for. */
+        pdp_active = (MM3gppPdpContextActive *)(l->data);
+        if (pdp_active->cid == self->priv->cid) {
+            status = (pdp_active->active ? MM_BEARER_CONNECTION_STATUS_CONNECTED : MM_BEARER_CONNECTION_STATUS_DISCONNECTED);
+            break;
+        }
+    }
+    mm_3gpp_pdp_context_active_list_free (pdp_active_list);
+
+    /* PDP context not found? This shouldn't happen, error out */
+    if (status == MM_BEARER_CONNECTION_STATUS_UNKNOWN)
+        g_task_return_new_error (task, MM_CORE_ERROR, MM_CORE_ERROR_FAILED,
+                                 "PDP context not found in the known contexts list");
+    else
+        g_task_return_int (task, (gssize) status);
+    g_object_unref (task);
+}
+
+static void
+load_connection_status (MMBaseBearer        *self,
+                        GAsyncReadyCallback  callback,
+                        gpointer             user_data)
+{
+    GTask       *task;
+    MMBaseModem *modem = NULL;
+
+    task = g_task_new (self, NULL, callback, user_data);
+
+    if (!MM_BROADBAND_BEARER (self)->priv->cid) {
+        g_task_return_new_error (task, MM_CORE_ERROR, MM_CORE_ERROR_FAILED,
+                                 "Couldn't load connection status: cid not defined");
+        g_object_unref (task);
+        return;
+    }
+
+    g_object_get (MM_BASE_BEARER (self),
+                  MM_BASE_BEARER_MODEM, &modem,
+                  NULL);
+
+    mm_base_modem_at_command (MM_BASE_MODEM (modem),
+                              "+CGACT?",
+                              3,
+                              FALSE,
+                              (GAsyncReadyCallback) cgact_periodic_query_ready,
+                              task);
+
+    g_object_unref (modem);
+}
+
 /*****************************************************************************/
 
 static void
@@ -2184,6 +2277,8 @@ mm_broadband_bearer_class_init (MMBroadbandBearerClass *klass)
     base_bearer_class->disconnect = disconnect;
     base_bearer_class->disconnect_finish = disconnect_finish;
     base_bearer_class->report_connection_status = report_connection_status;
+    base_bearer_class->load_connection_status = load_connection_status;
+    base_bearer_class->load_connection_status_finish = load_connection_status_finish;
 
     klass->connect_3gpp = connect_3gpp;
     klass->connect_3gpp_finish = detailed_connect_finish;