systemdshared.h

/*
 * Copyright 2014 Red Hat Inc., Durham, North Carolina.
 * All Rights Reserved.
 *
 * 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 2.1 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Authors:
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <dbus/dbus.h>
#include "common/debug_priv.h"

// Old versions of libdbus API don't have DBusBasicValue and DBus8ByteStruct
// as a public typedefs.
// These two typedefs were copied from libdbus 1.8 branch, see
// http://cgit.freedesktop.org/dbus/dbus/tree/dbus/dbus-types.h?h=dbus-1.8#n137
typedef struct
{
        dbus_uint32_t first32;
        dbus_uint32_t second32;
} _DBus8ByteStruct;

typedef union
{
        unsigned char bytes[8]; 
        dbus_int16_t  i16;   
        dbus_uint16_t u16;   
        dbus_int32_t  i32;   
        dbus_uint32_t u32;   
        dbus_bool_t   bool_val; 
#ifdef DBUS_HAVE_INT64
        dbus_int64_t  i64;   
        dbus_uint64_t u64;   
#endif
        _DBus8ByteStruct eight; 
        double dbl;          
        unsigned char byt;   
        char *str;           
        int fd;              
} _DBusBasicValue;

static char *get_path_by_unit(DBusConnection *conn, const char *unit)
{
        DBusMessage *msg = NULL;
        DBusPendingCall *pending = NULL;
        _DBusBasicValue path;
        char *ret = NULL;

        msg = dbus_message_new_method_call(
                "org.freedesktop.systemd1",
                "/org/freedesktop/systemd1",
                "org.freedesktop.systemd1.Manager",
                // LoadUnit is similar to GetUnit except it will load the unit file
                // if it hasn't been loaded yet.
                "LoadUnit"
        );
        if (msg == NULL) {
                dI("Failed to create dbus_message via dbus_message_new_method_call!");
                goto cleanup;
        }

        DBusMessageIter args;

        dbus_message_iter_init_append(msg, &args);
        if (!dbus_message_iter_append_basic(&args, DBUS_TYPE_STRING, &unit)) {
                dI("Failed to append unit '%s' string parameter to dbus message!", unit);
                goto cleanup;
        }

        if (!dbus_connection_send_with_reply(conn, msg, &pending, -1)) {
                dI("Failed to send message via dbus!");
                goto cleanup;
        }
        if (pending == NULL) {
                dI("Invalid dbus pending call!");
                goto cleanup;
        }

        dbus_connection_flush(conn);
        dbus_message_unref(msg); msg = NULL;

        dbus_pending_call_block(pending);
        msg = dbus_pending_call_steal_reply(pending);
        if (msg == NULL) {
                dI("Failed to steal dbus pending call reply.");
                goto cleanup;
        }
        dbus_pending_call_unref(pending); pending = NULL;

        if (!dbus_message_iter_init(msg, &args)) {
                dI("Failed to initialize iterator over received dbus message.");
                goto cleanup;
        }

        if (dbus_message_iter_get_arg_type(&args) != DBUS_TYPE_OBJECT_PATH) {
                dI("Expected string argument in reply. Instead received: %s.", dbus_message_type_to_string(dbus_message_iter_get_arg_type(&args)));
                goto cleanup;
        }

        dbus_message_iter_get_basic(&args, &path);
        ret = oscap_strdup(path.str);
        dbus_message_unref(msg); msg = NULL;

cleanup:
        if (pending != NULL)
                dbus_pending_call_unref(pending);

        if (msg != NULL)
                dbus_message_unref(msg);

        return ret;
}

static int get_all_systemd_units(DBusConnection* conn, int(*callback)(const char *, void *), void *cbarg)
{
        DBusMessage *msg = NULL;
        DBusPendingCall *pending = NULL;
        char ret = 1;

        msg = dbus_message_new_method_call(
                "org.freedesktop.systemd1",
                "/org/freedesktop/systemd1",
                "org.freedesktop.systemd1.Manager",
                "ListUnits"
        );
        if (msg == NULL) {
                dI("Failed to create dbus_message via dbus_message_new_method_call!");
                goto cleanup;
        }

        DBusMessageIter args, unit_iter;

        // the args should be empty for this call
        dbus_message_iter_init_append(msg, &args);

        if (!dbus_connection_send_with_reply(conn, msg, &pending, -1)) {
                dI("Failed to send message via dbus!");
                goto cleanup;
        }
        if (pending == NULL) {
                dI("Invalid dbus pending call!");
                goto cleanup;
        }

        dbus_connection_flush(conn);
        dbus_message_unref(msg); msg = NULL;

        dbus_pending_call_block(pending);
        msg = dbus_pending_call_steal_reply(pending);
        if (msg == NULL) {
                dI("Failed to steal dbus pending call reply.");
                goto cleanup;
        }
        dbus_pending_call_unref(pending); pending = NULL;

        if (!dbus_message_iter_init(msg, &args)) {
                dI("Failed to initialize iterator over received dbus message.");
                goto cleanup;
        }

        if (dbus_message_iter_get_arg_type(&args) != DBUS_TYPE_ARRAY) {
                dI("Expected array of structs in reply. Instead received: %s.", dbus_message_type_to_string(dbus_message_iter_get_arg_type(&args)));
                goto cleanup;
        }

        dbus_message_iter_recurse(&args, &unit_iter);
        do {
                if (dbus_message_iter_get_arg_type(&unit_iter) != DBUS_TYPE_STRUCT) {
                        dI("Expected unit struct as elements in returned array. Instead received: %s.", dbus_message_type_to_string(dbus_message_iter_get_arg_type(&unit_iter)));
                        goto cleanup;
                }

                DBusMessageIter unit_name;
                dbus_message_iter_recurse(&unit_iter, &unit_name);

                if (dbus_message_iter_get_arg_type(&unit_name) != DBUS_TYPE_STRING) {
                        dI("Expected string as the first element in the unit struct. Instead received: %s.", dbus_message_type_to_string(dbus_message_iter_get_arg_type(&unit_name)));
                        goto cleanup;
                }

                _DBusBasicValue value;
                dbus_message_iter_get_basic(&unit_name, &value);
                char *unit_name_s = oscap_strdup(value.str);
                int cbret = callback(unit_name_s, cbarg);
                oscap_free(unit_name_s);
                if (cbret != 0) {
                        goto cleanup;
                }
        }
        while (dbus_message_iter_next(&unit_iter));

        dbus_message_unref(msg); msg = NULL;

        ret = 0;

cleanup:
        if (pending != NULL)
                dbus_pending_call_unref(pending);

        if (msg != NULL)
                dbus_message_unref(msg);

        return ret;
}

static char *dbus_value_to_string(DBusMessageIter *iter)
{
        const int arg_type = dbus_message_iter_get_arg_type(iter);
        if (dbus_type_is_basic(arg_type)) {
                _DBusBasicValue value;
                dbus_message_iter_get_basic(iter, &value);

                switch (arg_type)
                {
                        case DBUS_TYPE_BYTE:
                                return oscap_sprintf("%c", value.byt);

                        case DBUS_TYPE_BOOLEAN:
                                return oscap_strdup(value.bool_val ? "true" : "false");

                        case DBUS_TYPE_INT16:
                                return oscap_sprintf("%i", value.i16);

                        case DBUS_TYPE_UINT16:
                                return oscap_sprintf("%u", value.u16);

                        case DBUS_TYPE_INT32:
                                return oscap_sprintf("%i", value.i32);

                        case DBUS_TYPE_UINT32:
                                return oscap_sprintf("%u", value.u32);

#ifdef DBUS_HAVE_INT64
                        case DBUS_TYPE_INT64:
                                return oscap_sprintf("%lli", value.i32);

                        case DBUS_TYPE_UINT64:
                                return oscap_sprintf("%llu", value.u32);
#endif

                        case DBUS_TYPE_DOUBLE:
                                return oscap_sprintf("%g", value.dbl);

                        case DBUS_TYPE_STRING:
                        case DBUS_TYPE_OBJECT_PATH:
                        case DBUS_TYPE_SIGNATURE:
                                return oscap_strdup(value.str);

                        // non-basic types
                        //case DBUS_TYPE_ARRAY:
                        //case DBUS_TYPE_STRUCT:
                        //case DBUS_TYPE_DICT_ENTRY:
                        //case DBUS_TYPE_VARIANT:

                        //case DBUS_TYPE_UNIX_FD:
                        //      return oscap_sprintf("%i", value.fd);

                        default:
                                dI("Encountered unknown dbus basic type!");
                                return oscap_strdup("error, unknown basic type!");
                }
        }
        else if (arg_type == DBUS_TYPE_ARRAY) {
                DBusMessageIter array;
                dbus_message_iter_recurse(iter, &array);

                char *ret = NULL;
                do {
                        char *element = dbus_value_to_string(&array);

                        if (element == NULL)
                                continue;

                        char *old_ret = ret;
                        if (old_ret == NULL)
                                ret = oscap_sprintf("%s", element);
                        else
                                ret = oscap_sprintf("%s, %s", old_ret, element);

                        oscap_free(old_ret);
                        oscap_free(element);
                }
                while (dbus_message_iter_next(&array));

                return ret;
        }/*
        else if (arg_type == DBUS_TYPE_VARIANT) {
                DBusMessageIter inner;
                dbus_message_iter_recurse(iter, &inner);
                return dbus_value_to_string(&inner);
        }*/

        return NULL;
}

static DBusConnection *connect_dbus()
{
        DBusConnection *conn = NULL;

        DBusError err;
        dbus_error_init(&err);

        conn = dbus_bus_get(DBUS_BUS_SYSTEM, &err);
        if (dbus_error_is_set(&err)) {
                dI("Failed to get DBUS_BUS_SYSTEM connection - %s", err.message);
                goto cleanup;
        }
        if (conn == NULL) {
                dI("DBusConnection == NULL!");
                goto cleanup;
        }

        dbus_bus_register(conn, &err);
        if (dbus_error_is_set(&err)) {
                dI("Failed to register on dbus - %s", err.message);
                goto cleanup;
        }

cleanup:
        dbus_error_free(&err);

        return conn;
}

static void disconnect_dbus(DBusConnection *conn)
{
        // NOOP

        // Connections retrieved via dbus_bus_get shall not be destroyed,
        // these connections are shared.
}

---