// SPDX-License-Identifier: BSD-2-Clause
/*
  Copyright (c) 2012-2018, Matthias Schiffer <mschiffer@universe-factory.net>
  All rights reserved.
*/

/**
   \file

   Status socket support
*/


#include "types.h"


#ifdef WITH_STATUS_SOCKET

#include "method.h"
#include "peer.h"

#include <json-c/json.h>
#include <net/if.h>
#include <sys/file.h>
#include <sys/un.h>


/** Argument for dump_thread */
typedef struct dump_thread_arg {
	int fd;                   /**< The file descriptor of an accepted socket connection */
	struct json_object *json; /**< The JSON object to write to the status socket */
} dump_thread_arg_t;


/** Thread to write the status JSON to the status socket */
static void *dump_thread(void *p) {
	dump_thread_arg_t *arg = p;

	const char *str = json_object_to_json_string(arg->json);
	size_t left = strlen(str);

	while (left > 0) {
		ssize_t written = write(arg->fd, str, left);
		if (written < 0) {
			pr_error_errno("can't dump status: write");
			break;
		}

		left -= written;
		str += written;
	}

	close(arg->fd);
	json_object_put(arg->json);
	free(arg);

	return NULL;
}


/** Dumps a single traffic stat as a JSON object */
static json_object *dump_stat(const fastd_stats_t *stats, fastd_stat_type_t type) {
	struct json_object *ret = json_object_new_object();

	json_object_object_add(ret, "packets", json_object_new_int64(stats->packets[type]));
	json_object_object_add(ret, "bytes", json_object_new_int64(stats->bytes[type]));

	return ret;
}

/** Dumps a single traffic stat as a JSON object */
static json_object *dump_iface(const fastd_iface_t *iface) {
	return (iface && iface->name) ? json_object_new_string(iface->name) : NULL;
}

/** Dumps a fastd_stats_t as a JSON object */
static json_object *dump_stats(const fastd_stats_t *stats) {
	struct json_object *statistics = json_object_new_object();

	json_object_object_add(statistics, "rx", dump_stat(stats, STAT_RX));
	json_object_object_add(statistics, "rx_reordered", dump_stat(stats, STAT_RX_REORDERED));

	json_object_object_add(statistics, "tx", dump_stat(stats, STAT_TX));
	json_object_object_add(statistics, "tx_dropped", dump_stat(stats, STAT_TX_DROPPED));
	json_object_object_add(statistics, "tx_error", dump_stat(stats, STAT_TX_ERROR));

	return statistics;
}


/** Dumps a peer's status as a JSON object */
static json_object *dump_peer(const fastd_peer_t *peer) {
	struct json_object *ret = json_object_new_object();

	/* '[' + IPv6 addresss + '%' + interface + ']:' + port + NUL */
	char addr_buf[1 + INET6_ADDRSTRLEN + 2 + IFNAMSIZ + 1 + 5 + 1];
	fastd_snprint_peer_address(addr_buf, sizeof(addr_buf), &peer->address, NULL, false, false);

	json_object_object_add(ret, "name", peer->name ? json_object_new_string(peer->name) : NULL);
	json_object_object_add(ret, "address", json_object_new_string(addr_buf));

	if (!ctx.iface)
		json_object_object_add(ret, "interface", dump_iface(peer->iface));

	struct json_object *connection = NULL;

	if (fastd_peer_is_established(peer)) {
		connection = json_object_new_object();

		json_object_object_add(connection, "established", json_object_new_int64(ctx.now - peer->established));

		struct json_object *method = NULL;

		const fastd_method_info_t *method_info = conf.protocol->get_current_method(peer);

		if (method_info)
			method = json_object_new_string(method_info->name);

		json_object_object_add(connection, "method", method);

		json_object_object_add(connection, "statistics", dump_stats(&peer->stats));

		if (conf.mode == MODE_TAP) {
			struct json_object *mac_addresses = json_object_new_array();
			json_object_object_add(connection, "mac_addresses", mac_addresses);

			size_t i;
			for (i = 0; i < VECTOR_LEN(ctx.eth_addrs); i++) {
				fastd_peer_eth_addr_t *addr = &VECTOR_INDEX(ctx.eth_addrs, i);

				if (addr->peer != peer)
					continue;

				const uint8_t *d = addr->addr.data;

				char eth_addr_buf[18];
				snprintf(
					eth_addr_buf, sizeof(eth_addr_buf), "%02x:%02x:%02x:%02x:%02x:%02x", d[0], d[1],
					d[2], d[3], d[4], d[5]);

				json_object_array_add(mac_addresses, json_object_new_string(eth_addr_buf));
			}
		}
	}

	json_object_object_add(ret, "connection", connection);

	return ret;
}

/** Dumps fastd's status to a connected socket */
static void dump_status(int fd) {
	struct json_object *json = json_object_new_object();

	json_object_object_add(json, "uptime", json_object_new_int64(ctx.now - ctx.started));

	if (ctx.iface)
		json_object_object_add(json, "interface", dump_iface(ctx.iface));

	json_object_object_add(json, "statistics", dump_stats(&ctx.stats));

	struct json_object *peers = json_object_new_object();
	json_object_object_add(json, "peers", peers);

	size_t i;
	for (i = 0; i < VECTOR_LEN(ctx.peers); i++) {
		fastd_peer_t *peer = VECTOR_INDEX(ctx.peers, i);

		if (!fastd_peer_is_enabled(peer))
			continue;

		char buf[65];
		if (conf.protocol->describe_peer(peer, buf, sizeof(buf)))
			json_object_object_add(peers, buf, dump_peer(peer));
	}


	dump_thread_arg_t *arg = fastd_new(dump_thread_arg_t);

	arg->json = json;
	arg->fd = fd;

	pthread_t thread;
	if ((errno = pthread_create(&thread, &ctx.detached_thread, dump_thread, arg)) != 0) {
		pr_error_errno("unable to create status dump thread");

		close(arg->fd);
		json_object_put(arg->json);
		free(arg);
	}
}

/** Deletes the status socket file */
static void unlink_status_socket(void) {
	if (!conf.status_socket || ctx.status_fd.fd < 0)
		return;

	if (unlink(conf.status_socket))
		pr_warn_errno("unlink_status_socket: unlink");
}

static void status_socket_lock(void) {
	const char *lock_format = "%s.lock";

	size_t lockname_len = strlen(lock_format) + strlen(conf.status_socket) + 1;
	char lockname[lockname_len];
	snprintf(lockname, lockname_len, lock_format, conf.status_socket);

	int lock_fd = open(lockname, O_RDONLY | O_CREAT, 0600);
	if (lock_fd < 0)
		exit_errno("unable to open status socket lock file");

	if (flock(lock_fd, LOCK_EX | LOCK_NB)) {
		switch (errno) {
		case EWOULDBLOCK:
			exit_error("status socket already in use");

		default:
			exit_error("unable to set status socket lock");
		}
	}
}

/** Initialized the status socket */
void fastd_status_init(void) {
	if (!conf.status_socket) {
		ctx.status_fd.fd = -1;
		return;
	}

#ifdef USE_USER
	uid_t uid = geteuid();
	gid_t gid = getegid();

	if (conf.user || conf.group) {
		if (setegid(conf.gid) < 0)
			pr_debug_errno("setegid");
		if (seteuid(conf.uid) < 0)
			pr_debug_errno("seteuid");
	}
#endif

	status_socket_lock();

	if (unlink(conf.status_socket) == 0)
		pr_info("removing old status socket");
	else if (errno != ENOENT)
		pr_warn_errno("unable to remove old status socket");

	ctx.status_fd = FASTD_POLL_FD(POLL_TYPE_STATUS, socket(AF_UNIX, SOCK_STREAM, 0));
	if (ctx.status_fd.fd < 0)
		exit_errno("fastd_status_init: socket");


	size_t status_socket_len = strlen(conf.status_socket);
	size_t len = offsetof(struct sockaddr_un, sun_path) + status_socket_len + 1;
	uint8_t buf[len] __attribute__((aligned(__alignof__(struct sockaddr_un))));
	memset(buf, 0, offsetof(struct sockaddr_un, sun_path));

	struct sockaddr_un *sa = (struct sockaddr_un *)buf;

	sa->sun_family = AF_UNIX;
	memcpy(sa->sun_path, conf.status_socket, status_socket_len + 1);

	if (bind(ctx.status_fd.fd, (struct sockaddr *)sa, len)) {
		switch (errno) {
		case EADDRINUSE:
			exit_error("unable to create status socket: the path `%s' already exists", conf.status_socket);

		default:
			exit_errno("unable to create status socket");
		}
	}

	if (atexit(unlink_status_socket)) {
		pr_error_errno("atexit");
		unlink_status_socket();
		exit(1);
	}

	if (listen(ctx.status_fd.fd, 4))
		exit_errno("fastd_status_init: listen");


#ifdef USE_USER
	if (seteuid(uid) < 0)
		pr_debug_errno("seteuid");
	if (setegid(gid) < 0)
		pr_debug_errno("setegid");
#endif

	fastd_poll_fd_register(&ctx.status_fd);
}

/** Closes the status socket */
void fastd_status_close(void) {
	if (!conf.status_socket || ctx.status_fd.fd < 0)
		return;

	if (!fastd_poll_fd_close(&ctx.status_fd))
		pr_warn_errno("fastd_status_cleanup: close");

	unlink_status_socket();

	ctx.status_fd.fd = -1;
}

/** Handles a single connection on the status socket */
void fastd_status_handle(void) {
	int fd = accept(ctx.status_fd.fd, NULL, NULL);

	if (fd < 0) {
		pr_warn_errno("fastd_status_handle: accept");
		return;
	}

	dump_status(fd);
}

#endif
