cinterion: Fix CDC-ECM support for ELS61-E2

When the data connection is started with AT^SWWAN, the modem expects
the DHCP discover packet from the TE while the command is running,
i.e. while the modem has not replied yet. In order to achieve that,
the bearer is marked as connected as soon as the command is
issued. This makes the NetworkManager start the DHCP process.

If the modem replies with an error, the bearer will be marked
disconnected later on.

See https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/merge_requests/50
for a similar functionality in the ublox driver.

Includes minor coding style fixes from Aleksander Morgado
<aleksandermj@chromium.org>.

Signed-off-by: Christian Taedcke <christian.taedcke@lemonbeat.com>

1 files changed, 48 insertions, 7 deletions

diff --git a/plugins/cinterion/mm-broadband-bearer-cinterion.c b/plugins/cinterion/mm-broadband-bearer-cinterion.c
index e7ff392c..e67d461c 100644
--- a/plugins/cinterion/mm-broadband-bearer-cinterion.c
+++ b/plugins/cinterion/mm-broadband-bearer-cinterion.c
@@ -272,6 +272,23 @@ common_dial_operation_ready (MMBaseModem  *modem,
 }
 
 static void
+swwan_dial_operation_ready (MMBaseModem                *modem,
+                            GAsyncResult               *res,
+                            MMBroadbandBearerCinterion *self) /* full ref! */
+{
+    GError *error = NULL;
+
+    if (!mm_base_modem_at_command_full_finish (modem, res, &error)) {
+        mm_obj_warn (self, "data connection attempt failed: %s", error->message);
+        mm_base_bearer_report_connection_status (MM_BASE_BEARER (self),
+                                                 MM_BEARER_CONNECTION_STATUS_DISCONNECTED);
+        g_error_free (error);
+    }
+
+    g_object_unref (self);
+}
+
+static void
 handle_cancel_dial (GTask *task)
 {
     Dial3gppContext *ctx;
@@ -299,6 +316,8 @@ dial_3gpp_context_step (GTask *task)
 {
     MMBroadbandBearerCinterion *self;
     Dial3gppContext            *ctx;
+    MMCinterionModemFamily      modem_family;
+    gboolean                    default_swwan_behavior;
 
     self = g_task_get_source_object (task);
     ctx  = g_task_get_task_data (task);
@@ -310,16 +329,19 @@ dial_3gpp_context_step (GTask *task)
         return;
     }
 
+    modem_family = mm_broadband_modem_cinterion_get_family (MM_BROADBAND_MODEM_CINTERION (ctx->modem));
+    default_swwan_behavior = modem_family == MM_CINTERION_MODEM_FAMILY_DEFAULT;
+
     switch (ctx->step) {
     case DIAL_3GPP_CONTEXT_STEP_FIRST:
         ctx->step++;
         /* fall through */
 
     case DIAL_3GPP_CONTEXT_STEP_AUTH: {
-        gchar *command;
+        g_autofree gchar *command = NULL;
 
         command = mm_cinterion_build_auth_string (self,
-                                                  mm_broadband_modem_cinterion_get_family (MM_BROADBAND_MODEM_CINTERION (ctx->modem)),
+                                                  modem_family,
                                                   mm_base_bearer_peek_config (MM_BASE_BEARER (ctx->self)),
                                                   ctx->cid);
 
@@ -336,7 +358,6 @@ dial_3gpp_context_step (GTask *task)
                                            NULL,
                                            (GAsyncReadyCallback) common_dial_operation_ready,
                                            task);
-            g_free (command);
             return;
         }
 
@@ -345,13 +366,31 @@ dial_3gpp_context_step (GTask *task)
     } /* fall through */
 
     case DIAL_3GPP_CONTEXT_STEP_START_SWWAN: {
-        gchar *command;
+        g_autofree gchar *command = NULL;
 
         mm_obj_dbg (self, "dial step %u/%u: starting SWWAN interface %u connection...",
                     ctx->step, DIAL_3GPP_CONTEXT_STEP_LAST, usb_interface_configs[ctx->usb_interface_config_index].swwan_index);
         command = g_strdup_printf ("^SWWAN=1,%u,%u",
                                    ctx->cid,
                                    usb_interface_configs[ctx->usb_interface_config_index].swwan_index);
+
+        if (default_swwan_behavior) {
+            mm_base_modem_at_command_full (ctx->modem,
+                                           ctx->primary,
+                                           command,
+                                           MM_BASE_BEARER_DEFAULT_CONNECTION_TIMEOUT,
+                                           FALSE,
+                                           FALSE,
+                                           NULL,
+                                           (GAsyncReadyCallback) common_dial_operation_ready,
+                                           task);
+            return;
+        }
+
+        /* We "jump" to the last step here here since the modem expects the
+         * DHCP discover packet while ^SWWAN runs. If the command fails,
+         * we'll mark the bearer disconnected later in the callback.
+         */
         mm_base_modem_at_command_full (ctx->modem,
                                        ctx->primary,
                                        command,
@@ -359,13 +398,15 @@ dial_3gpp_context_step (GTask *task)
                                        FALSE,
                                        FALSE,
                                        NULL,
-                                       (GAsyncReadyCallback) common_dial_operation_ready,
-                                       task);
-        g_free (command);
+                                       (GAsyncReadyCallback) swwan_dial_operation_ready,
+                                       g_object_ref (self));
+        ctx->step = DIAL_3GPP_CONTEXT_STEP_LAST;
+        dial_3gpp_context_step (task);
         return;
     }
 
     case DIAL_3GPP_CONTEXT_STEP_VALIDATE_CONNECTION:
+        g_assert (default_swwan_behavior);
         mm_obj_dbg (self, "dial step %u/%u: checking SWWAN interface %u status...",
                     ctx->step, DIAL_3GPP_CONTEXT_STEP_LAST, usb_interface_configs[ctx->usb_interface_config_index].swwan_index);
         load_connection_status_by_cid (ctx->self,