/* -*- Mode: C; tab-width: 4; indent-tabs-mode: t; c-basic-offset: 4 -*- */
/*
 * Copyright (C) 2010 Dan Williams <dcbw@redhat.com>
 * Copyright (C) 2016 Sjoerd Simons <sjoerd@luon.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include "nm-default.h"

#include "nm-dns-systemd-resolved.h"

#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <sys/stat.h>
#include <linux/if.h>

#include "nm-core-internal.h"
#include "nm-platform.h"
#include "nm-utils.h"
#include "nm-ip4-config.h"
#include "nm-ip6-config.h"
#include "nm-bus-manager.h"
#include "nm-manager.h"
#include "nm-device.h"
#include "NetworkManagerUtils.h"

G_DEFINE_TYPE (NMDnsSystemdResolved, nm_dns_systemd_resolved, NM_TYPE_DNS_PLUGIN)

#define NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE(o) \
  (G_TYPE_INSTANCE_GET_PRIVATE ((o), NM_TYPE_DNS_SYSTEMD_RESOLVED, \
    NMDnsSystemdResolvedPrivate))

#define SYSTEMD_RESOLVED_DBUS_SERVICE "org.freedesktop.resolve1"
#define SYSTEMD_RESOLVED_DBUS_PATH "/org/freedesktop/resolve1"

typedef struct {
	int ifindex;
	GList *configs;
} InterfaceConfig;

typedef struct {
	GDBusProxy *resolve;
	GCancellable *init_cancellable;
	GCancellable *update_cancellable;
	GQueue dns_updates;
	GQueue domain_updates;
} NMDnsSystemdResolvedPrivate;

/*****************************************************************************/

#define _NMLOG_DOMAIN         LOGD_DNS
#define _NMLOG_PREFIX_NAME    "systemd-resolved"
#define _NMLOG(level, ...) \
    G_STMT_START { \
        nm_log ((level), _NMLOG_DOMAIN, \
                "%s[%p]: " _NM_UTILS_MACRO_FIRST(__VA_ARGS__), \
                _NMLOG_PREFIX_NAME, \
                (self) \
                _NM_UTILS_MACRO_REST(__VA_ARGS__)); \
    } G_STMT_END

/*****************************************************************************/

static void
call_done (GObject *source, GAsyncResult *r, gpointer user_data)
{
	GVariant *v;
	GError *error = NULL;
	NMDnsSystemdResolved *self = (NMDnsSystemdResolved *) user_data;

	v = g_dbus_proxy_call_finish (G_DBUS_PROXY (source), r, &error);

	if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
		return;

	if (error != NULL) {
		_LOGW ("Failed: %s\n", error->message);
		g_error_free (error);
	}
}

static void
add_interface_configuration (NMDnsSystemdResolved *self,
                             GArray *interfaces,
                             const NMDnsIPConfigData *data)
{
	int i;
	InterfaceConfig *ic = NULL;
	int ifindex;
	NMDevice *device;

	if (NM_IS_IP4_CONFIG (data->config))
		ifindex = nm_ip4_config_get_ifindex (data->config);
	else if (NM_IS_IP6_CONFIG  (data->config))
		ifindex = nm_ip6_config_get_ifindex (data->config);
	else
		g_return_if_reached ();

	device = nm_manager_get_device_by_ifindex (nm_manager_get (), ifindex);

	if (!nm_device_get_managed (device, FALSE))
		return;

	for (i = 0; i < interfaces->len; i++) {
		InterfaceConfig *tic = &g_array_index (interfaces, InterfaceConfig, i);
		if (ifindex == tic->ifindex) {
			ic = tic;
			break;
		}
	}

	if (!ic) {
		g_array_set_size (interfaces, interfaces->len + 1);
		ic = &g_array_index (interfaces, InterfaceConfig,
		                     interfaces->len - 1);
		ic->ifindex = ifindex;
	}

	ic->configs = g_list_append (ic->configs, data->config);
}

static void
add_domain (GVariantBuilder *domains,
            const char *domain,
            gboolean never_default)
{
	/* If this link is never the default (e.g. only used for resources on this
	 * network) add a routing domain. */
	g_variant_builder_add (domains, "(sb)", domain, never_default);
}

static void
update_add_ip6_config (NMDnsSystemdResolved *self,
                       GVariantBuilder *dns,
                       GVariantBuilder *domains,
                       const NMIP6Config *config)
{
	guint i, n;

	n = nm_ip6_config_get_num_nameservers (config);
	for (i = 0 ; i < n; i++) {
		const struct in6_addr *ip;

		g_variant_builder_open (dns, G_VARIANT_TYPE ("(iay)"));
		g_variant_builder_add (dns, "i", AF_INET6);
		ip = nm_ip6_config_get_nameserver (config, i),

		g_variant_builder_add_value (dns, g_variant_new_fixed_array (G_VARIANT_TYPE_BYTE, ip, 16, 1));
		g_variant_builder_close (dns);
	}

	n = nm_ip6_config_get_num_searches (config);
	if (n > 0) {
		for (i = 0; i < n; i++) {
			add_domain (domains, nm_ip6_config_get_search (config, i),
			            nm_ip6_config_get_never_default (config));
		}
	} else {
		n = nm_ip6_config_get_num_domains (config);
		for (i = 0; i < n; i++) {
			add_domain (domains, nm_ip6_config_get_domain (config, i),
			            nm_ip6_config_get_never_default (config));
		}
	}
}

static void
update_add_ip4_config (NMDnsSystemdResolved *self,
                       GVariantBuilder *dns,
                       GVariantBuilder *domains,
                       const NMIP4Config *config)
{
	guint i, n;

	n = nm_ip4_config_get_num_nameservers (config);
	for (i = 0 ; i < n; i++) {
		guint32 ns;

		g_variant_builder_open (dns, G_VARIANT_TYPE ("(iay)"));
		g_variant_builder_add (dns, "i", AF_INET);
		ns = nm_ip4_config_get_nameserver (config, i),

		g_variant_builder_add_value (dns, g_variant_new_fixed_array (G_VARIANT_TYPE_BYTE, &ns, 4, 1));
		g_variant_builder_close (dns);
	}

	n = nm_ip4_config_get_num_searches (config);
	if (n  > 0) {
		for (i = 0; i < n; i++) {
			add_domain (domains, nm_ip4_config_get_search (config, i),
			            nm_ip4_config_get_never_default (config));
		}
	} else {
		n = nm_ip4_config_get_num_domains (config);
		for (i = 0; i < n; i++) {
			add_domain (domains, nm_ip4_config_get_domain (config, i),
			            nm_ip4_config_get_never_default (config));
		}
	}
}

static void
free_pending_updates (NMDnsSystemdResolved *self)
{
	NMDnsSystemdResolvedPrivate *priv = NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE (self);
	GVariant *v;

	while ((v = g_queue_pop_head (&priv->dns_updates)) != NULL)
		g_variant_unref (v);

	while ((v = g_queue_pop_head (&priv->domain_updates)) != NULL)
		g_variant_unref (v);
}

static void
prepare_one_interface (NMDnsSystemdResolved *self, InterfaceConfig *ic)
{
	NMDnsSystemdResolvedPrivate *priv = NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE (self);
	GVariantBuilder dns, domains;
	GList *l;

	g_variant_builder_init (&dns, G_VARIANT_TYPE ("(ia(iay))"));
	g_variant_builder_add (&dns, "i", ic->ifindex);
	g_variant_builder_open (&dns, G_VARIANT_TYPE ("a(iay)"));

	g_variant_builder_init (&domains, G_VARIANT_TYPE ("(ia(sb))"));
	g_variant_builder_add (&domains, "i", ic->ifindex);
	g_variant_builder_open (&domains, G_VARIANT_TYPE ("a(sb)"));

	for (l = ic->configs ; l != NULL ; l = g_list_next (l)) {
		if (NM_IS_IP4_CONFIG (l->data))
			update_add_ip4_config (self, &dns, &domains, l->data);
		else if (NM_IS_IP6_CONFIG (l->data))
			update_add_ip6_config (self, &dns, &domains, l->data);
		else
			g_assert_not_reached ();
	}
	g_variant_builder_close (&dns);
	g_variant_builder_close (&domains);

	g_queue_push_tail (&priv->dns_updates,
	                   g_variant_ref_sink (g_variant_builder_end (&dns)));
	g_queue_push_tail (&priv->domain_updates,
	                   g_variant_ref_sink (g_variant_builder_end (&domains)));
}

static void
send_updates (NMDnsSystemdResolved *self)
{
	NMDnsSystemdResolvedPrivate *priv = NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE (self);
	GVariant *v;

	nm_clear_g_cancellable (&priv->update_cancellable);

	if (!priv->resolve)
		return;

	priv->update_cancellable = g_cancellable_new ();

	while ((v = g_queue_pop_head (&priv->dns_updates)) != NULL) {
		g_dbus_proxy_call (priv->resolve, "SetLinkDNS", v,
		                   G_DBUS_CALL_FLAGS_NONE,
		                   -1, priv->update_cancellable, call_done, self);
		g_variant_unref (v);
	}

	while ((v = g_queue_pop_head (&priv->domain_updates)) != NULL) {
		g_dbus_proxy_call (priv->resolve, "SetLinkDomains", v,
		                   G_DBUS_CALL_FLAGS_NONE,
		                   -1, priv->update_cancellable, call_done, self);
		g_variant_unref (v);
	}
}

static gboolean
update (NMDnsPlugin *plugin,
        const NMDnsIPConfigData **configs,
        const NMGlobalDnsConfig *global_config,
        const char *hostname)
{
	NMDnsSystemdResolved *self = NM_DNS_SYSTEMD_RESOLVED (plugin);
	GArray *interfaces = g_array_new (TRUE, TRUE, sizeof (InterfaceConfig));
	const NMDnsIPConfigData **c;
	int i;

	for (c = configs; *c != NULL; c++)
		add_interface_configuration (self, interfaces, *c);

	free_pending_updates (self);

	for (i = 0; i < interfaces->len; i++) {
		InterfaceConfig *ic = &g_array_index (interfaces, InterfaceConfig, i);

		prepare_one_interface (self, ic);
		g_list_free (ic->configs);
	}

	g_array_free (interfaces, TRUE);

	send_updates (self);

	return TRUE;
}

/****************************************************************/

static gboolean
is_caching (NMDnsPlugin *plugin)
{
	return TRUE;
}

static const char *
get_name (NMDnsPlugin *plugin)
{
	return "systemd-resolved";
}

/****************************************************************/

NMDnsPlugin *
nm_dns_systemd_resolved_new (void)
{
	return g_object_new (NM_TYPE_DNS_SYSTEMD_RESOLVED, NULL);
}

static void
resolved_proxy_created (GObject *source, GAsyncResult *r, gpointer user_data)
{
	NMDnsSystemdResolved *self = (NMDnsSystemdResolved *) user_data;
	NMDnsSystemdResolvedPrivate *priv;
	gs_free_error GError *error = NULL;
	GDBusProxy *resolve;

	resolve = g_dbus_proxy_new_finish (r, &error);
	if (   !resolve
	    && g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
		return;

	priv = NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE (self);
	g_clear_object (&priv->init_cancellable);
	if (!resolve) {
		_LOGW ("failed to connect to resolved via DBus: %s", error->message);
		g_signal_emit_by_name (self, NM_DNS_PLUGIN_FAILED);
		return;
	}

	priv->resolve = resolve;
	send_updates (self);
}


static void
nm_dns_systemd_resolved_init (NMDnsSystemdResolved *self)
{
	NMDnsSystemdResolvedPrivate *priv = NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE (self);
	NMBusManager *dbus_mgr;
	GDBusConnection *connection;

	g_queue_init (&priv->dns_updates);
	g_queue_init (&priv->domain_updates);

	dbus_mgr = nm_bus_manager_get ();
	g_return_if_fail (dbus_mgr);

	connection = nm_bus_manager_get_connection (dbus_mgr);
	g_return_if_fail (connection);

	priv->init_cancellable = g_cancellable_new ();
	g_dbus_proxy_new (connection,
	                  G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
	                  G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS,
	                  NULL,
	                  SYSTEMD_RESOLVED_DBUS_SERVICE,
	                  SYSTEMD_RESOLVED_DBUS_PATH,
	                  SYSTEMD_RESOLVED_DBUS_SERVICE ".Manager",
	                  priv->init_cancellable,
	                  resolved_proxy_created,
	                  self);
}

static void
dispose (GObject *object)
{
	NMDnsSystemdResolved *self = NM_DNS_SYSTEMD_RESOLVED (object);
	NMDnsSystemdResolvedPrivate *priv = NM_DNS_SYSTEMD_RESOLVED_GET_PRIVATE (self);

	free_pending_updates (self);
	g_clear_object (&priv->resolve);
	nm_clear_g_cancellable (&priv->init_cancellable);
	nm_clear_g_cancellable (&priv->update_cancellable);

	G_OBJECT_CLASS (nm_dns_systemd_resolved_parent_class)->dispose (object);
}

static void
nm_dns_systemd_resolved_class_init (NMDnsSystemdResolvedClass *dns_class)
{
	NMDnsPluginClass *plugin_class = NM_DNS_PLUGIN_CLASS (dns_class);
	GObjectClass *object_class = G_OBJECT_CLASS (dns_class);

	g_type_class_add_private (dns_class, sizeof (NMDnsSystemdResolvedPrivate));

	object_class->dispose = dispose;

	plugin_class->is_caching = is_caching;
	plugin_class->update = update;
	plugin_class->get_name = get_name;
}

