/*
 *
 *  Wireless daemon for Linux
 *
 *  Copyright (C) 2019  Intel Corporation. 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

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

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <linux/if_ether.h>
#include <fnmatch.h>

#include <ell/ell.h>

#include "linux/nl80211.h"

#include "src/iwd.h"
#include "src/netdev.h"
#include "src/wiphy.h"
#include "src/util.h"
#include "src/common.h"

static struct l_genl_family *nl80211 = NULL;

struct wiphy_setup_state {
	uint32_t id;
	struct wiphy *wiphy;
	struct l_timeout *setup_timeout;
	unsigned int pending_cmd_count;
	bool aborted;
};

static struct l_queue *pending_wiphys;

static void wiphy_setup_state_free(void *data)
{
	struct wiphy_setup_state *state = data;

	l_queue_remove(pending_wiphys, state);

	if (state->setup_timeout)
		l_timeout_remove(state->setup_timeout);

	L_WARN_ON(state->pending_cmd_count);
	l_free(state);
}

static void manager_new_interface_cb(struct l_genl_msg *msg, void *user_data)
{
	struct wiphy_setup_state *state = user_data;

	l_debug("");

	if (state->aborted)
		return;

	if (l_genl_msg_get_error(msg) < 0) {
		l_error("NEW_INTERFACE failed: %s",
			strerror(-l_genl_msg_get_error(msg)));
		/*
		 * Nothing we can do to use this wiphy since by now we
		 * will have successfully deleted any default interface
		 * there may have been.
		 */
		return;
	}

	netdev_create_from_genl(msg);
}

static void manager_new_interface_done(void *user_data)
{
	struct wiphy_setup_state *state = user_data;

	state->pending_cmd_count--;
	wiphy_setup_state_free(state);
}

static void manager_create_interfaces(struct wiphy_setup_state *state)
{
	struct l_genl_msg *msg;
	char ifname[10];
	uint32_t iftype = NL80211_IFTYPE_STATION;
	unsigned cmd_id;

	if (state->aborted) {
		wiphy_setup_state_free(state);
		return;
	}

	/*
	 * Current policy: we maintain one netdev per wiphy for station,
	 * AP and Ad-Hoc modes, one optional p2p-device and zero or more
	 * p2p-GOs or p2p-clients.  The P2P-related interfaces will be
	 * created on request.
	 */

	/* To be improved */
	snprintf(ifname, sizeof(ifname), "wlan%i", (int) state->id);
	l_debug("creating %s", ifname);

	msg = l_genl_msg_new(NL80211_CMD_NEW_INTERFACE);
	l_genl_msg_append_attr(msg, NL80211_ATTR_WIPHY, 4, &state->id);
	l_genl_msg_append_attr(msg, NL80211_ATTR_IFTYPE, 4, &iftype);
	l_genl_msg_append_attr(msg, NL80211_ATTR_IFNAME,
				strlen(ifname) + 1, ifname);
	l_genl_msg_append_attr(msg, NL80211_ATTR_4ADDR, 1, "\0");
	l_genl_msg_append_attr(msg, NL80211_ATTR_SOCKET_OWNER, 0, "");
	cmd_id = l_genl_family_send(nl80211, msg,
					manager_new_interface_cb, state,
					manager_new_interface_done);

	if (!cmd_id) {
		l_error("Sending NEW_INTERFACE for %s", ifname);
		wiphy_setup_state_free(state);
		return;
	}

	state->pending_cmd_count++;
}

static void manager_setup_cmd_done(void *user_data)
{
	struct wiphy_setup_state *state = user_data;

	state->pending_cmd_count--;

	if (!state->pending_cmd_count)
		manager_create_interfaces(state);
}

static void manager_del_interface_cb(struct l_genl_msg *msg, void *user_data)
{
	struct wiphy_setup_state *state = user_data;

	l_debug("");

	if (state->aborted)
		return;

	if (l_genl_msg_get_error(msg) < 0)
		l_error("DEL_INTERFACE failed: %s",
			strerror(-l_genl_msg_get_error(msg)));
}

static void manager_get_interface_cb(struct l_genl_msg *msg, void *user_data)
{
	struct wiphy_setup_state *state = user_data;
	struct l_genl_attr attr;
	uint16_t type, len;
	const void *data;
	const uint32_t *ifindex = NULL, *iftype = NULL;
	const uint64_t *wdev_idx = NULL;
	const char *ifname = NULL;
	struct l_genl_msg *del_msg;
	unsigned cmd_id;

	l_debug("");

	if (state->aborted)
		return;

	if (!l_genl_attr_init(&attr, msg))
		return;

	while (l_genl_attr_next(&attr, &type, &len, &data)) {
		switch (type) {
		case NL80211_ATTR_IFINDEX:
			if (len != sizeof(uint32_t)) {
				l_warn("Invalid interface index attribute");
				return;
			}

			ifindex = data;
			break;

		case NL80211_ATTR_WDEV:
			if (len != sizeof(uint64_t)) {
				l_warn("Invalid wdev index attribute");
				return;
			}

			wdev_idx = data;
			break;


		case NL80211_ATTR_WIPHY:
			if (len != sizeof(uint32_t) ||
					*((uint32_t *) data) != state->id) {
				l_warn("Invalid wiphy attribute");
				return;
			}

			break;

		case NL80211_ATTR_IFTYPE:
			if (len != sizeof(uint32_t)) {
				l_warn("Invalid interface type attribute");
				return;
			}

			iftype = data;
			break;

		case NL80211_ATTR_IFNAME:
			if (len < 1 || !memchr(data + 1, 0, len - 1)) {
				l_warn("Invalid interface name attribute");
				return;
			}

			ifname = data;
			break;
		}
	}

	if (!ifindex || !wdev_idx || !iftype || !ifname)
		return;

	del_msg = l_genl_msg_new(NL80211_CMD_DEL_INTERFACE);
	l_genl_msg_append_attr(del_msg, NL80211_ATTR_IFINDEX, 4, ifindex);
	l_genl_msg_append_attr(del_msg, NL80211_ATTR_WDEV, 8, wdev_idx);
	l_genl_msg_append_attr(del_msg, NL80211_ATTR_WIPHY, 4, &state->id);
	cmd_id = l_genl_family_send(nl80211, del_msg,
					manager_del_interface_cb, state,
					manager_setup_cmd_done);

	if (!cmd_id) {
		l_error("Sending DEL_INTERFACE for %s failed", ifname);
		return;
	}

	l_debug("");
	state->pending_cmd_count++;
}

static void manager_wiphy_dump_interfaces(struct wiphy_setup_state *state)
{
	struct l_genl_msg *msg;
	unsigned cmd_id;

	if (state->setup_timeout) {
		l_timeout_remove(state->setup_timeout);
		state->setup_timeout = NULL;
	}

	/*
	 * As the first step after new wiphy is detected we will query
	 * the initial interface setup, delete the default interfaces
	 * and create interfaces for our own use with NL80211_ATTR_SOCKET_OWNER
	 * on them.  After that if new interfaces are created outside of
	 * IWD, or removed outside of IWD, we don't touch them and will
	 * try to minimally adapt to handle the removals correctly.  It's
	 * a very unlikely situation in any case but it wouldn't make
	 * sense to try to continually enforce our setup fighting against
	 * some other process, and it wouldn't make sense to try to
	 * manage and use additional interfaces beyond the one or two
	 * we need for our operations.
	 */

	msg = l_genl_msg_new(NL80211_CMD_GET_INTERFACE);
	l_genl_msg_append_attr(msg, NL80211_ATTR_WIPHY, 4, &state->id);
	cmd_id = l_genl_family_dump(nl80211, msg,
					manager_get_interface_cb, state,
					manager_setup_cmd_done);

	if (!cmd_id) {
		l_error("Querying interface information for wiphy %u failed",
			(unsigned int) state->id);
		wiphy_setup_state_free(state);
		return;
	}

	l_debug("");
	state->pending_cmd_count++;
}

static void manager_wiphy_setup_timeout(struct l_timeout *timeout,
					void *user_data)
{
	struct wiphy_setup_state *state = user_data;

	manager_wiphy_dump_interfaces(state);
}

static void manager_new_wiphy_event(struct l_genl_msg *msg)
{
	struct wiphy_setup_state *state;
	struct wiphy *wiphy;
	struct l_genl_attr attr;
	uint32_t id;
	const char *name;

	if (!pending_wiphys)
		return;

	if (!l_genl_attr_init(&attr, msg))
		return;

	if (!wiphy_parse_id_and_name(&attr, &id, &name))
		return;

	wiphy = wiphy_find(id);
	if (!wiphy) {
		wiphy = wiphy_create(id, name);

		if (!wiphy)
			return;
	}

	wiphy_update_from_genl(wiphy, msg);

	/*
	 * We've got a new wiphy, flag it as new and wait for a
	 * NEW_INTERFACE event for this wiphy's default driver-created
	 * interface.  That event's handler will check the flag and
	 * finish setting up the interfaces for this new wiphy and then
	 * clear the flag.  In some corner cases there may be no
	 * default interface on this wiphy and no user-space created
	 * interfaces from before IWD started, so set a 1-second timeout
	 * for the event.  The timeout pointer is also used as the flag.
	 */

	state = l_new(struct wiphy_setup_state, 1);
	state->id = id;
	state->wiphy = wiphy;
	state->setup_timeout = l_timeout_create(1, manager_wiphy_setup_timeout,
						state, NULL);
	l_queue_push_tail(pending_wiphys, state);
}

static bool manager_wiphy_state_match(const void *a, const void *b)
{
	const struct wiphy_setup_state *state = a;
	uint32_t id = L_PTR_TO_UINT(b);

	return (state->id == id);
}

static struct wiphy_setup_state *manager_find_pending(uint32_t id)
{
	return l_queue_find(pending_wiphys, manager_wiphy_state_match,
				L_UINT_TO_PTR(id));
}

static uint32_t manager_parse_ifindex(struct l_genl_attr *attr)
{
	uint16_t type, len;
	const void *data;

	while (l_genl_attr_next(attr, &type, &len, &data)) {
		if (type != NL80211_ATTR_IFINDEX)
			continue;

		if (len != sizeof(uint32_t))
			break;

		return *((uint32_t *) data);
	}

	return -1;
}

static uint32_t manager_parse_wiphy_id(struct l_genl_attr *attr)
{
	uint16_t type, len;
	const void *data;

	while (l_genl_attr_next(attr, &type, &len, &data)) {
		if (type != NL80211_ATTR_WIPHY)
			continue;

		if (len != sizeof(uint32_t))
			break;

		return *((uint32_t *) data);
	}

	return -1;
}

static void manager_del_wiphy_event(struct l_genl_msg *msg)
{
	struct wiphy_setup_state *state;
	struct wiphy *wiphy;
	struct l_genl_attr attr;
	uint32_t id;

	if (!l_genl_attr_init(&attr, msg))
		return;

	id = manager_parse_wiphy_id(&attr);

	state = manager_find_pending(id);
	if (state) {
		if (state->pending_cmd_count)
			state->aborted = true;
		else
			wiphy_setup_state_free(state);
	}

	wiphy = wiphy_find(id);
	if (wiphy)
		wiphy_destroy(wiphy);
}

static void manager_config_notify(struct l_genl_msg *msg, void *user_data)
{
	uint8_t cmd;
	struct wiphy_setup_state *state;
	struct l_genl_attr attr;
	struct netdev *netdev;

	cmd = l_genl_msg_get_command(msg);

	l_debug("Notification of command %u", cmd);

	switch (cmd) {
	case NL80211_CMD_NEW_WIPHY:
		manager_new_wiphy_event(msg);
		break;

	case NL80211_CMD_DEL_WIPHY:
		manager_del_wiphy_event(msg);
		break;

	case NL80211_CMD_NEW_INTERFACE:
		/*
		 * If we have a NEW_INTERFACE for a freshly detected wiphy
		 * assume we can now query for the default or pre-created
		 * interfaces, remove any we don't need and create our own.
		 */
		if (!l_genl_attr_init(&attr, msg))
			break;

		state = manager_find_pending(manager_parse_wiphy_id(&attr));
		if (!state || !state->setup_timeout)
			break;

		manager_wiphy_dump_interfaces(state);
		break;

	case NL80211_CMD_DEL_INTERFACE:
		if (!l_genl_attr_init(&attr, msg))
			break;

		netdev = netdev_find(manager_parse_ifindex(&attr));
		if (!netdev)
			break;

		netdev_destroy(netdev);
		break;
	}
}

static void manager_wiphy_dump_callback(struct l_genl_msg *msg, void *user_data)
{
	l_debug("");

	manager_new_wiphy_event(msg);
}

bool manager_init(struct l_genl_family *in)
{
	nl80211 = in;

	if (!l_genl_family_register(nl80211, "config", manager_config_notify,
					NULL, NULL))
		l_error("Registering for config notifications failed");

	if (!l_genl_family_dump(nl80211,
				l_genl_msg_new(NL80211_CMD_GET_WIPHY),
				manager_wiphy_dump_callback,
				NULL, NULL))
		l_error("Initial wiphy information dump failed");

	pending_wiphys = l_queue_new();

	return true;
}

void manager_exit(void)
{
	l_queue_destroy(pending_wiphys, NULL);
	pending_wiphys = NULL;

	nl80211 = NULL;
}