port-probe: add a new serial parser filter to detect non-AT strings

We will check each string with our custom filter before even trying to
parse them. A MM_SERIAL_ERROR_PARSE_FAILED error will be issued whenever the
string doesn't match the filter.

3 files changed, 33 insertions, 5 deletions

diff --git a/include/ModemManager-errors.h b/include/ModemManager-errors.h
index 0be24abb..ed714573 100644
--- a/include/ModemManager-errors.h
+++ b/include/ModemManager-errors.h
@@ -209,6 +209,7 @@ typedef enum { /*< underscore_name=mm_connection_error >*/
  * @MM_SERIAL_ERROR_OPEN_FAILED_NO_DEVICE: Could not open the serial port, no device.
  * @MM_SERIAL_ERROR_FLASH_FAILED: Could not flash the device.
  * @MM_SERIAL_ERROR_NOT_OPEN: The serial port is not open.
+ * @MM_SERIAL_ERROR_PARSE_FAILED: The serial port specific parsing failed.
  *
  * Serial errors that may be reported by ModemManager.
  */
@@ -220,6 +221,7 @@ typedef enum { /*< underscore_name=mm_serial_error >*/
     MM_SERIAL_ERROR_OPEN_FAILED_NO_DEVICE = 4, /*< nick=OpenFailedNoDevice >*/
     MM_SERIAL_ERROR_FLASH_FAILED          = 5, /*< nick=FlashFailed        >*/
     MM_SERIAL_ERROR_NOT_OPEN              = 6, /*< nick=NotOpen            >*/
+    MM_SERIAL_ERROR_PARSE_FAILED          = 7, /*< nick=ParseFailed        >*/
 } MMSerialError;
 
 /**
diff --git a/src/mm-port-probe-at.c b/src/mm-port-probe-at.c
index d7e6fefe..10cce9e5 100644
--- a/src/mm-port-probe-at.c
+++ b/src/mm-port-probe-at.c
@@ -50,11 +50,15 @@ mm_port_probe_response_processor_is_at (const gchar *command,
             return FALSE;
         }
 
-        /* If error is NOT known by the parser, request to abort */
-        if (!mm_serial_parser_v1_is_known_error (error)) {
+        /* If error is NOT known by the parser, or if the error is actually
+         * the generic parsing filter error, request to abort */
+        if (!mm_serial_parser_v1_is_known_error (error) ||
+            g_error_matches (error,
+                             MM_SERIAL_ERROR,
+                             MM_SERIAL_ERROR_PARSE_FAILED)) {
             *result_error = g_error_copy (error);
             g_prefix_error (result_error,
-                            "Fatal error parsing AT reply. ");
+                            "Fatal error parsing AT reply: ");
             return FALSE;
         }
 
@@ -91,4 +95,3 @@ mm_port_probe_response_processor_string (const gchar *command,
 
     return TRUE;
 }
-
diff --git a/src/mm-port-probe.c b/src/mm-port-probe.c
index 6c36e6ba..33f0be86 100644
--- a/src/mm-port-probe.c
+++ b/src/mm-port-probe.c
@@ -955,6 +955,23 @@ serial_buffer_full (MMSerialPort *serial,
 }
 
 static gboolean
+serial_parser_filter_cb (gpointer filter,
+                         gpointer user_data,
+                         GString *response,
+                         GError **error)
+{
+    if (is_non_at_response ((const guint8 *) response->str, response->len)) {
+        g_set_error (error,
+                     MM_SERIAL_ERROR,
+                     MM_SERIAL_ERROR_PARSE_FAILED,
+                     "Not an AT response");
+        return FALSE;
+    }
+
+    return TRUE;
+}
+
+static gboolean
 serial_open_at (MMPortProbe *self)
 {
     PortProbeRunTask *task = self->priv->task;
@@ -968,6 +985,8 @@ serial_open_at (MMPortProbe *self)
 
     /* Create AT serial port if not done before */
     if (!task->serial) {
+        gpointer parser;
+
         task->serial = MM_SERIAL_PORT (mm_at_serial_port_new (g_udev_device_get_name (self->priv->port)));
         if (!task->serial) {
             port_probe_run_task_complete (
@@ -989,9 +1008,13 @@ serial_open_at (MMPortProbe *self)
                       MM_SERIAL_PORT_SPEW_CONTROL,   TRUE,
                       NULL);
 
+        parser = mm_serial_parser_v1_new ();
+        mm_serial_parser_v1_add_filter (parser,
+                                        serial_parser_filter_cb,
+                                        NULL);
         mm_at_serial_port_set_response_parser (MM_AT_SERIAL_PORT (task->serial),
                                                mm_serial_parser_v1_parse,
-                                               mm_serial_parser_v1_new (),
+                                               parser,
                                                mm_serial_parser_v1_destroy);
     }