libnm-glib: add helper to connect to NM's private D-Bus socket

A number of places in the code need to get a connection to NM through
D-Bus, and that connection could be either a shared bus connection or
a private connection.  Consolidate that logic.

Unfortunately only dbus-glib >= 0.100 correctly supports private
connections (commit 8b7e4a1c4ae055864e26db4addbcc2dc38ee6963 fixes
this problem) so the private connection functionality is not enabled
for older dbus-glib versions.

libnm-glib/Makefile.am

@@ -47,7 +47,8 @@ lib_LTLIBRARIES = libnm-glib.la libnm-glib-vpn.la
 libnm_glib_la_CFLAGS = \
 	$(GLIB_CFLAGS) \
 	$(DBUS_CFLAGS) \
-	$(GUDEV_CFLAGS)
+	$(GUDEV_CFLAGS) \
+	-DNMRUNDIR=\"$(nmrundir)\"
 
 libnmincludedir = $(includedir)/libnm-glib
 libnmvpndir = $(includedir)/libnm-glib
@@ -89,6 +90,7 @@ libnmvpn_HEADERS = \
 
 libnm_glib_la_csources = \
 	nm-object.c \
+	nm-dbus-helpers.c \
 	nm-client.c \
 	nm-device.c \
 	nm-device-ethernet.c \
@@ -124,7 +126,8 @@ libnm_glib_la_private_headers = \
 	nm-types-private.h \
 	nm-object-cache.h \
 	nm-remote-connection-private.h \
-	nm-glib-marshal.h
+	nm-glib-marshal.h \
+	nm-dbus-helpers-private.h
 
 libnm_glib_la_SOURCES = \
 	$(libnm_glib_la_csources) \
@@ -179,7 +182,8 @@ libnm_glib_test_la_CFLAGS = \
 	$(GLIB_CFLAGS) \
 	$(DBUS_CFLAGS) \
 	$(GUDEV_CFLAGS) \
-	-DLIBNM_GLIB_TEST
+	-DLIBNM_GLIB_TEST \
+	-DNMRUNDIR=\"$(nmrundir)\"
 
 libnm_glib_test_la_SOURCES = \
 	$(libnminclude_HEADERS) \

libnm-glib/nm-dbus-helpers-private.h

@@ -0,0 +1,38 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
+/*
+ * libnm_glib -- Access network status & information from glib applications
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ * Copyright (C) 2013 Red Hat, Inc.
+ */
+
+#ifndef NM_DBUS_HELPERS_PRIVATE_H
+#define NM_DBUS_HELPERS_PRIVATE_H
+
+#include <gio/gio.h>
+#include <dbus/dbus.h>
+#include <dbus/dbus-glib-lowlevel.h>
+
+DBusGConnection *_nm_dbus_new_connection (GError **error);
+
+gboolean         _nm_dbus_is_connection_private (DBusGConnection *connection);
+
+DBusGProxy *     _nm_dbus_new_proxy_for_connection (DBusGConnection *connection,
+                                                    const char *path,
+                                                    const char *interface);
+
+#endif /* NM_DBUS_HELPERS_PRIVATE_H */

libnm-glib/nm-dbus-helpers.c

@@ -0,0 +1,106 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
+/*
+ * libnm_glib -- Access network status & information from glib applications
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ * Copyright (C) 2013 Red Hat, Inc.
+ */
+
+#include <string.h>
+#include <config.h>
+#include <gio/gio.h>
+#include <dbus/dbus.h>
+#include <dbus/dbus-glib-lowlevel.h>
+#include "nm-dbus-helpers-private.h"
+#include "NetworkManager.h"
+
+static dbus_int32_t priv_slot = -1;
+
+static gboolean
+_ensure_dbus_data_slot (void)
+{
+	static gsize init_value = 0;
+	gboolean success = TRUE;
+
+	if (g_once_init_enter (&init_value)) {
+		success = dbus_connection_allocate_data_slot (&priv_slot);
+		g_once_init_leave (&init_value, 1);
+	}
+	return success;
+}
+
+DBusGConnection *
+_nm_dbus_new_connection (GError **error)
+{
+	DBusGConnection *connection = NULL;
+
+	if (!_ensure_dbus_data_slot ()) {
+		g_set_error (error, DBUS_GERROR, DBUS_GERROR_FAILED, "failed to allocated data slot");
+		return NULL;
+	}
+
+#if HAVE_DBUS_GLIB_100
+	/* If running as root try the private bus first */
+	if (0 == geteuid ()) {
+		connection = dbus_g_connection_open ("unix:path=" NMRUNDIR "/private", error);
+		if (connection) {
+			DBusConnection *dbus_connection = dbus_g_connection_get_connection (connection);
+
+			/* Mark this connection as private */
+			dbus_connection_set_data (dbus_connection, priv_slot, GUINT_TO_POINTER (TRUE), NULL);
+			dbus_connection_set_exit_on_disconnect (dbus_connection, FALSE);
+			return connection;
+		}
+		/* Fall back to a bus if for some reason private socket isn't available */
+		g_clear_error (error);
+	}
+#endif
+
+	if (connection == NULL) {
+#ifdef LIBNM_GLIB_TEST
+		connection = dbus_g_bus_get (DBUS_BUS_SESSION, error);
+#else
+		connection = dbus_g_bus_get (DBUS_BUS_SYSTEM, error);
+#endif
+	}
+
+	return connection;
+}
+
+gboolean
+_nm_dbus_is_connection_private (DBusGConnection *connection)
+{
+	if (!_ensure_dbus_data_slot ())
+		return FALSE;
+	return !!dbus_connection_get_data (dbus_g_connection_get_connection (connection), priv_slot);
+}
+DBusGProxy *
+_nm_dbus_new_proxy_for_connection (DBusGConnection *connection,
+                                   const char *path,
+                                   const char *interface)
+{
+	/* Private connections can't use dbus_g_proxy_new_for_name() or
+	 * dbus_g_proxy_new_for_name_owner() because peer-to-peer connections don't
+	 * have either a bus daemon or name owners, both of which those functions
+	 * require.
+	 */
+	if (_nm_dbus_is_connection_private (connection))
+		return dbus_g_proxy_new_for_peer (connection, path, interface);
+
+	return dbus_g_proxy_new_for_name (connection, NM_DBUS_SERVICE, path, interface);
+}
+