[wlanloader] WLAN loader plugin

Apparently Android by default resets the WLAN driver after
every use of WLAN hotspot. To make it easier to work with android
kernels whose WLAN module depends on this kind of reset service,
this plugin will imitate that behavior by reloading the
kernel module via a systemd service after each use of
WLAN hotspot.

If you want to utilize this plugin, please add a systemd system
service that is named "wlan-module-load.service" to your adaptation
project. The service should modprobe the wlan kernel module at
ExecStart, and rmmod it at ExecStop.

If the systemd service is not present in the system, the plugin will
not do anything.

Signed-off-by: Kalle Jokiniemi <kalle.jokiniemi@jolla.com>

configure.ac

@@ -169,6 +169,19 @@ AS_IF([test "x$enable_vibra_feedback" != xno],
   [AC_DEFINE([DSME_VIBRA_FEEDBACK], [1])])
 AM_CONDITIONAL([WANT_VIBRA_FEEDBACK], [test x$enable_vibra_feedback != xno])
 
+#
+# WLAN loader
+#
+AC_ARG_ENABLE([wlanloader],
+  [AS_HELP_STRING([--disable-wlan-loader],
+    [disable wlan loader (libwlanloader)])],
+  [enable_wlan_loader=no],
+  [enable_wlan_loader=yes])
+
+AS_IF([test "x$enable_wlan_loader" != xno],
+  [AC_DEFINE([DSME_WLAN_LOADER], [1])])
+AM_CONDITIONAL([WANT_WLAN_LOADER], [test x$enable_wlan_loader != xno])
+
 #
 # Compiler and linker flags
 #

modules/Makefile.am

@@ -79,6 +79,10 @@ if WANT_VIBRA_FEEDBACK
 pkglib_LTLIBRARIES += shutdownfeedback.la
 endif
 
+if WANT_WLAN_LOADER
+pkglib_LTLIBRARIES += wlanloader.la
+endif
+
 startup_la_SOURCES = startup.c
 
 # TODO: remove this
@@ -215,3 +219,8 @@ shutdownfeedback_la_SOURCES = shutdownfeedback.c vibrafeedback.c vibrafeedback.h
 shutdownfeedback_la_CFLAGS = $(AM_CFLAGS) $(GLIB_CFLAGS) $(DBUS_CFLAGS) $(LIBNGF_CFLAGS) -D_GNU_SOURCE
 shutdownfeedback_la_LIBADD = $(GLIB_LIBS) $(LIBNGF_LIBS)
 endif
+
+if WANT_WLAN_LOADER
+wlanloader_la_SOURCES = wlanloader.c
+wlanloader_la_CFLAGS = $(AM_CFLAGS) $(DBUS_CFLAGS) -D_GNU_SOURCE
+endif

modules/dsme_dbus.c

@@ -243,6 +243,28 @@ bool dsme_dbus_message_get_bool(const DsmeDbusMessage* msg)
   return b;
 }
 
+bool dsme_dbus_message_get_variant_bool(const DsmeDbusMessage* msg)
+{
+  // FIXME: caller can't tell apart FALSE from error
+  dbus_bool_t b = FALSE;
+
+  if( msg ) {
+      DBusMessageIter *iter = (DBusMessageIter *)&msg->iter;
+      DBusMessageIter subiter;
+
+      if( dsme_dbus_check_arg_type(iter, DBUS_TYPE_VARIANT) ) {
+          dbus_message_iter_recurse (iter, &subiter);
+          if( dsme_dbus_check_arg_type(&subiter, DBUS_TYPE_BOOLEAN) ) {
+	      dbus_message_iter_get_basic(&subiter, &b);
+          }
+      }
+
+      dbus_message_iter_next(iter);
+  }
+
+  return b;
+}
+
 static void message_send_and_delete(DsmeDbusMessage* msg)
 {
   // TODO: check for errors and log them

modules/dsme_dbus.h

@@ -81,6 +81,7 @@ void dsme_dbus_message_append_int(DsmeDbusMessage* msg, int i);
 int         dsme_dbus_message_get_int(const DsmeDbusMessage* msg);
 const char* dsme_dbus_message_get_string(const DsmeDbusMessage* msg);
 bool        dsme_dbus_message_get_bool(const DsmeDbusMessage* msg);
+bool        dsme_dbus_message_get_variant_bool(const DsmeDbusMessage* msg);
 
 // NOTE: frees the signal; hence not const
 void dsme_dbus_signal_emit(DsmeDbusMessage* sig);

modules/startup.c

@@ -117,6 +117,9 @@ const char *modules[] = {
 #endif
 #ifdef DSME_VIBRA_FEEDBACK
     "shutdownfeedback.so",
+#endif
+#ifdef DSME_WLAN_LOADER
+    "wlanloader.so",
 #endif
     NULL
 };

modules/wlanloader.c

@@ -0,0 +1,214 @@
+/**
+   @file wlanloader.c
+
+   @brief Plugin for resetting kernel WLAN module after wifi hotspot usage
+
+   Wlan loader plugin in it's current form simply listens to connman's
+   property "Tethering" changes, and resets the wlan kernel module by restarting
+   a systemd service called "wlan-module-load.service" each time "Tethering"
+   is set to false.
+
+   At start up, the plugin detects if "wlan-module-load.service" is present in
+   systemd and only becomes active if it is found. If your hardware platform
+   requires WLAN to be reset after wifi hotspot use, please provide a
+   systemd system service named "wlan-module-load.service", that at ExecStart
+   modprobes the wlan kernel module, and at ExecStop rmmods the module.
+
+   <p>
+   Copyright (C) 2014 Jolla Ltd.
+
+   @author Kalle Jokiniemi <kalle.jokiniemi@jolla.com>
+
+   This file is part of Dsme.
+
+   Dsme is free software; you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License
+   version 2.1 as published by the Free Software Foundation.
+
+   Dsme is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with Dsme.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdbool.h>
+#include <string.h>
+
+#include "dbusproxy.h"
+#include "dsme_dbus.h"
+#include "dsme/modules.h"
+#include "dsme/logging.h"
+
+#define WLAN_SYSTEMD_UNIT   "wlan-module-load.service"
+
+static void reset_wlan_module(void)
+{
+    DBusError        err  = DBUS_ERROR_INIT;
+    DBusConnection  *conn = 0;
+    DBusMessage     *req  = NULL;
+    const char      *unit = WLAN_SYSTEMD_UNIT;
+    const char      *mode = "ignore-requirements";
+
+    dsme_log(LOG_DEBUG, "wlanloader: Resetting WLAN");
+
+    if (!(conn = dsme_dbus_get_connection(&err)))
+    {
+	dsme_log(LOG_ERR, "wlanloader: system bus connect: %s: %s",
+		 err.name, err.message);
+        goto cleanup;
+    }
+
+    req = dbus_message_new_method_call("org.freedesktop.systemd1",
+                               "/org/freedesktop/systemd1",
+                               "org.freedesktop.systemd1.Manager",
+                               "RestartUnit");
+    if (!req)
+        goto cleanup;
+
+    if (!dbus_message_append_args(req,
+                            DBUS_TYPE_STRING, &unit,
+                            DBUS_TYPE_STRING, &mode,
+                            DBUS_TYPE_INVALID)) {
+        goto cleanup;
+    }
+
+    if (!dbus_connection_send(conn, req, NULL))
+        goto cleanup;
+
+cleanup:
+
+    if (req) dbus_message_unref(req);
+    if (conn) dbus_connection_unref(conn);
+    dbus_error_free(&err);
+}
+
+static void connman_tethering_changed(const DsmeDbusMessage* sig)
+{
+    bool tethering;
+
+    if (strcmp(dsme_dbus_message_get_string(sig), "Tethering") == 0)
+    {
+        tethering = dsme_dbus_message_get_variant_bool(sig);
+        dsme_log(LOG_DEBUG, "wlanloader: Tethering status changed to %d",
+                                         tethering);
+
+        if (!tethering) {
+            reset_wlan_module();
+        }
+    }
+}
+
+static const dsme_dbus_signal_binding_t signals[] = {
+  { connman_tethering_changed , "net.connman.Technology", "PropertyChanged" },
+  { 0, 0 }
+};
+
+static bool bound = false;
+
+static void loader_needed_cb(DBusPendingCall *pending, void *user_data)
+{
+    (void)user_data;
+
+    DBusMessage *rsp = 0;
+    DBusError    err = DBUS_ERROR_INIT;
+
+    if (!(rsp = dbus_pending_call_steal_reply(pending)))
+        goto cleanup;
+
+    if (dbus_set_error_from_message(&err, rsp)) {
+        dsme_log(LOG_DEBUG, "wlanloader: disabled, GetUnit: %s: %s",
+                                                    err.name, err.message);
+    } else {
+        /* We got the reply without error, so the service exists */
+        dsme_dbus_bind_signals(&bound, signals);
+        dsme_log(LOG_DEBUG, "wlanloader: activated");
+    }
+
+cleanup:
+    if (rsp) dbus_message_unref(rsp);
+    dbus_error_free(&err);
+}
+
+/* Helper function to check if this module is needed */
+static void check_loader_needed(void)
+{
+    DBusError        err  = DBUS_ERROR_INIT;
+    DBusPendingCall *pc   = 0;
+    DBusConnection  *conn = 0;
+    DBusMessage     *req  = NULL;
+    const char      *unit = WLAN_SYSTEMD_UNIT;
+
+    if (!(conn = dsme_dbus_get_connection(&err)))
+    {
+	dsme_log(LOG_ERR, "wlanloader: system bus connect: %s: %s",
+		 err.name, err.message);
+        goto cleanup;
+    }
+
+    req = dbus_message_new_method_call("org.freedesktop.systemd1",
+                               "/org/freedesktop/systemd1",
+                               "org.freedesktop.systemd1.Manager",
+                               "GetUnit");
+    if (!req)
+        goto cleanup;
+
+    if (!dbus_message_append_args(req,
+                            DBUS_TYPE_STRING, &unit,
+                            DBUS_TYPE_INVALID)) {
+        goto cleanup;
+    }
+
+    if (!dbus_connection_send_with_reply(conn, req, &pc, -1))
+        goto cleanup;
+
+    if (!pc) {
+        dsme_log(LOG_WARNING, "wlanloader: null pending call received");
+        goto cleanup;
+    }
+
+    if (!dbus_pending_call_set_notify(pc, loader_needed_cb, 0, 0))
+        goto cleanup;
+
+cleanup:
+
+    if (pc) dbus_pending_call_unref(pc);
+    if (req) dbus_message_unref(req);
+    if (conn) dbus_connection_unref(conn);
+    dbus_error_free(&err);
+}
+
+DSME_HANDLER(DSM_MSGTYPE_DBUS_CONNECT, client, msg)
+{
+    dsme_log(LOG_DEBUG, "wlanloader: DBUS_CONNECT");
+
+    check_loader_needed();
+}
+
+DSME_HANDLER(DSM_MSGTYPE_DBUS_DISCONNECT, client, msg)
+{
+    dsme_log(LOG_DEBUG, "wlanloader: DBUS_DISCONNECT");
+    dsme_dbus_unbind_signals(&bound, signals);
+}
+
+module_fn_info_t message_handlers[] = {
+    DSME_HANDLER_BINDING(DSM_MSGTYPE_DBUS_CONNECT),
+    DSME_HANDLER_BINDING(DSM_MSGTYPE_DBUS_DISCONNECT),
+    { 0 }
+};
+
+void
+module_init(module_t * handle)
+{
+    dsme_log(LOG_DEBUG, "wlanloader.so loaded");
+}
+
+void
+module_fini(void)
+{
+    dsme_dbus_unbind_signals(&bound, signals);
+    dsme_log(LOG_DEBUG, "libwlanloader.so unloaded");
+}
+