mm-iface-modem: add check_for_sim_swap method and enable steps

When in low-power mode, some modems will not dispatch unsolicited
notifications, such as for SIM hot swapping. There is code in
MMBroadbandModemTelit to handle this by checking the SIM identifier
during modem power up against the identifier cached in the SIM
D-Bus object. If they're different, the SIM has likely been
swapped while we were powered down.

We can move this code out to MMBroadbandModem because it doesn't
actually rely on any Telit-specific details, and invoke it from
MMIfaceModem via a new method.

3 files changed, 170 insertions, 0 deletions

diff --git a/src/mm-broadband-modem.c b/src/mm-broadband-modem.c
index c97afc13..f82122b1 100644
--- a/src/mm-broadband-modem.c
+++ b/src/mm-broadband-modem.c
@@ -3357,6 +3357,132 @@ modem_power_up (MMIfaceModem *self,
 }
 
 /*****************************************************************************/
+/* Reprobing the modem if the SIM changed across a power-off or power-down */
+
+typedef struct {
+    MMBaseSim *sim;
+    guint retries;
+} SimSwapContext;
+
+static gboolean load_sim_identifier (GTask *task);
+
+static void
+sim_swap_context_free (SimSwapContext *ctx)
+{
+    g_clear_object (&ctx->sim);
+    g_slice_free (SimSwapContext, ctx);
+}
+
+static gboolean
+modem_check_for_sim_swap_finish (MMIfaceModem *self,
+                                 GAsyncResult *res,
+                                 GError **error)
+{
+    return g_task_propagate_boolean (G_TASK (res), error);
+}
+
+static void
+load_sim_identifier_ready (MMBaseSim *sim,
+                           GAsyncResult *res,
+                           GTask *task)
+{
+    MMBroadbandModem *self;
+    SimSwapContext *ctx;
+    const gchar *cached_simid;
+    gchar *current_simid;
+    GError *error = NULL;
+
+    self = MM_BROADBAND_MODEM (g_task_get_source_object (task));
+    ctx = g_task_get_task_data (task);
+    cached_simid = mm_gdbus_sim_get_sim_identifier (MM_GDBUS_SIM (sim));
+    current_simid = MM_BASE_SIM_GET_CLASS (sim)->load_sim_identifier_finish (sim, res, &error);
+
+    if (error) {
+        if (g_error_matches (error, MM_CORE_ERROR, MM_CORE_ERROR_UNSUPPORTED)) {
+            g_task_return_error (task, error);
+            goto out;
+        }
+
+        if (ctx->retries > 0) {
+            mm_warn ("could not load SIM identifier: %s (%d retries left)",
+                     error->message, ctx->retries);
+            --ctx->retries;
+            g_clear_error (&error);
+            g_timeout_add_seconds (1, (GSourceFunc) load_sim_identifier, task);
+            return;
+        }
+
+        mm_warn ("could not load SIM identifier: %s", error->message);
+        g_task_return_error (task, error);
+        goto out;
+    }
+
+    if (g_strcmp0 (current_simid, cached_simid) != 0) {
+        mm_info ("sim identifier has changed: possible SIM swap during power down/low");
+        mm_broadband_modem_update_sim_hot_swap_detected (self);
+    }
+
+    g_task_return_boolean (task, TRUE);
+
+out:
+    g_free (current_simid);
+    g_object_unref (task);
+}
+
+static gboolean
+load_sim_identifier (GTask *task)
+{
+    SimSwapContext *ctx = g_task_get_task_data (task);
+
+    MM_BASE_SIM_GET_CLASS (ctx->sim)->load_sim_identifier (
+        ctx->sim,
+        (GAsyncReadyCallback)load_sim_identifier_ready,
+        task);
+
+    return G_SOURCE_REMOVE;
+}
+
+static void
+modem_check_for_sim_swap (MMIfaceModem *self,
+                          GAsyncReadyCallback callback,
+                          gpointer user_data)
+{
+    GTask *task;
+    SimSwapContext *ctx;
+
+    mm_dbg ("Checking if SIM was swapped...");
+
+    task = g_task_new (self, NULL, callback, user_data);
+    ctx = g_slice_new0 (SimSwapContext);
+    ctx->retries = 3;
+    g_task_set_task_data (task, ctx, (GDestroyNotify)sim_swap_context_free);
+
+    g_object_get (self,
+                  MM_IFACE_MODEM_SIM, &ctx->sim,
+                  NULL);
+    if (!ctx->sim) {
+        g_task_return_new_error (task,
+                                 MM_CORE_ERROR,
+                                 MM_CORE_ERROR_FAILED,
+                                 "could not acquire sim object");
+        g_object_unref (task);
+        return;
+    }
+
+    if (!MM_BASE_SIM_GET_CLASS (ctx->sim)->load_sim_identifier ||
+        !MM_BASE_SIM_GET_CLASS (ctx->sim)->load_sim_identifier_finish) {
+        g_task_return_new_error (task,
+                                 MM_CORE_ERROR,
+                                 MM_CORE_ERROR_FAILED,
+                                 "sim identifier could not be loaded");
+        g_object_unref (task);
+        return;
+    }
+
+    load_sim_identifier (task);
+}
+
+/*****************************************************************************/
 /* Sending a command to the modem (Modem interface) */
 
 static const gchar *
@@ -10767,6 +10893,8 @@ iface_modem_init (MMIfaceModem *iface)
     /* Enabling steps */
     iface->modem_power_up = modem_power_up;
     iface->modem_power_up_finish = modem_power_up_finish;
+    iface->check_for_sim_swap = modem_check_for_sim_swap;
+    iface->check_for_sim_swap_finish = modem_check_for_sim_swap_finish;
     iface->setup_flow_control = modem_setup_flow_control;
     iface->setup_flow_control_finish = modem_setup_flow_control_finish;
     iface->load_supported_charsets = modem_load_supported_charsets;
diff --git a/src/mm-iface-modem.c b/src/mm-iface-modem.c
index afb3be32..7236e30b 100644
--- a/src/mm-iface-modem.c
+++ b/src/mm-iface-modem.c
@@ -3557,6 +3557,7 @@ static void interface_enabling_step (GTask *task);
 typedef enum {
     ENABLING_STEP_FIRST,
     ENABLING_STEP_SET_POWER_STATE,
+    ENABLING_STEP_CHECK_FOR_SIM_SWAP,
     ENABLING_STEP_FLOW_CONTROL,
     ENABLING_STEP_SUPPORTED_CHARSETS,
     ENABLING_STEP_CHARSET,
@@ -3607,6 +3608,25 @@ enabling_set_power_state_ready (MMIfaceModem *self,
 }
 
 static void
+check_for_sim_swap_ready (MMIfaceModem *self,
+                          GAsyncResult *res,
+                          GTask *task)
+{
+    EnablingContext *ctx;
+    GError *error = NULL;
+
+    if (!MM_IFACE_MODEM_GET_INTERFACE (self)->check_for_sim_swap_finish (self, res, &error)) {
+        mm_warn ("Error checking if SIM was swapped: '%s'", error->message);
+        g_error_free (error);
+    }
+
+    /* Go on to next step */
+    ctx = g_task_get_task_data (task);
+    ctx->step++;
+    interface_enabling_step (task);
+}
+
+static void
 setup_flow_control_ready (MMIfaceModem *self,
                           GAsyncResult *res,
                           GTask *task)
@@ -3709,6 +3729,18 @@ interface_enabling_step (GTask *task)
                                         task);
         return;
 
+    case ENABLING_STEP_CHECK_FOR_SIM_SWAP:
+        if (MM_IFACE_MODEM_GET_INTERFACE (self)->check_for_sim_swap &&
+            MM_IFACE_MODEM_GET_INTERFACE (self)->check_for_sim_swap_finish) {
+            MM_IFACE_MODEM_GET_INTERFACE (self)->check_for_sim_swap (
+                self,
+                (GAsyncReadyCallback)check_for_sim_swap_ready,
+                task);
+            return;
+        }
+        /* Fall down to next step */
+        ctx->step++;
+
     case ENABLING_STEP_FLOW_CONTROL:
         if (MM_IFACE_MODEM_GET_INTERFACE (self)->setup_flow_control &&
             MM_IFACE_MODEM_GET_INTERFACE (self)->setup_flow_control_finish) {
diff --git a/src/mm-iface-modem.h b/src/mm-iface-modem.h
index d25fbd49..177bf910 100644
--- a/src/mm-iface-modem.h
+++ b/src/mm-iface-modem.h
@@ -281,6 +281,16 @@ struct _MMIfaceModem {
                                              GAsyncResult *res,
                                              GError **error);
 
+    /* Asynchronous check to see if the SIM was swapped.
+     * Useful for when the modem changes power states since we might
+     * not get the relevant notifications from the modem. */
+    void (*check_for_sim_swap) (MMIfaceModem *self,
+                                GAsyncReadyCallback callback,
+                                gpointer user_data);
+    gboolean (*check_for_sim_swap_finish) (MMIfaceModem *self,
+                                           GAsyncResult *res,
+                                           GError **error);
+
     /* Asynchronous flow control setup */
     void (*setup_flow_control) (MMIfaceModem *self,
                                 GAsyncReadyCallback callback,