/*
  Copyright (c) 2012-2013, Matthias Schiffer <mschiffer@universe-factory.net>
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
    2. Redistributions in binary form must reproduce the above copyright notice,
       this list of conditions and the following disclaimer in the documentation
       and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/


#include "fastd.h"
#include "crypto.h"
#include "handshake.h"
#include "peer.h"

#include <fcntl.h>
#include <grp.h>
#include <poll.h>
#include <pthread.h>
#include <signal.h>
#include <string.h>
#include <syslog.h>
#include <sys/resource.h>


static volatile bool sighup = false;
static volatile bool terminate = false;
static volatile bool dump = false;


static void on_sighup(int signo UNUSED) {
	sighup = true;
}

static void on_terminate(int signo UNUSED) {
	terminate = true;
}

static void on_sigusr1(int signo UNUSED) {
	dump = true;
}

static void init_signals(fastd_context_t *ctx) {
	struct sigaction action;

	action.sa_flags = 0;
	sigemptyset(&action.sa_mask);

	action.sa_handler = on_sighup;
	if(sigaction(SIGHUP, &action, NULL))
		exit_errno(ctx, "sigaction");

	action.sa_handler = on_terminate;
	if(sigaction(SIGTERM, &action, NULL))
		exit_errno(ctx, "sigaction");
	if(sigaction(SIGQUIT, &action, NULL))
		exit_errno(ctx, "sigaction");
	if(sigaction(SIGINT, &action, NULL))
		exit_errno(ctx, "sigaction");

	action.sa_handler = on_sigusr1;
	if(sigaction(SIGUSR1, &action, NULL))
		exit_errno(ctx, "sigaction");

	action.sa_handler = SIG_IGN;
	if(sigaction(SIGPIPE, &action, NULL))
		exit_errno(ctx, "sigaction");
}

static void init_pipes(fastd_context_t *ctx) {
	int pipefd[2];

	if (pipe(pipefd))
		exit_errno(ctx, "pipe");

	fastd_setfd(ctx, pipefd[0], FD_CLOEXEC, 0);
	fastd_setfd(ctx, pipefd[1], FD_CLOEXEC, 0);

	ctx->resolverfd = pipefd[0];
	ctx->resolvewfd = pipefd[1];
}

static void init_log(fastd_context_t *ctx) {
	uid_t uid = geteuid();
	gid_t gid = getegid();

	if (ctx->conf->user || ctx->conf->group) {
		if (setegid(ctx->conf->gid) < 0)
			pr_debug_errno(ctx, "setegid");
		if (seteuid(ctx->conf->uid) < 0)
			pr_debug_errno(ctx, "seteuid");
	}

	if (ctx->conf->log_syslog_level > LL_UNSPEC)
		openlog(ctx->conf->log_syslog_ident, LOG_PID, LOG_DAEMON);

	fastd_log_file_t *config;
	for (config = ctx->conf->log_files; config; config = config->next) {
		fastd_log_fd_t *file = malloc(sizeof(fastd_log_fd_t));

		file->config = config;
		file->fd = open(config->filename, O_WRONLY|O_APPEND|O_CREAT, 0600);

		file->next = ctx->log_files;
		ctx->log_files = file;
	}

	if (seteuid(uid) < 0)
		pr_debug_errno(ctx, "seteuid");
	if (setegid(gid) < 0)
		pr_debug_errno(ctx, "setegid");
}

static void close_log(fastd_context_t *ctx) {
	while (ctx->log_files) {
		fastd_log_fd_t *next = ctx->log_files->next;

		close(ctx->log_files->fd);
		free(ctx->log_files);

		ctx->log_files = next;
	}

	closelog();
}

static void crypto_init(fastd_context_t *ctx UNUSED) {
#ifdef USE_CRYPTO_AES128CTR
	ctx->crypto_aes128ctr = ctx->conf->crypto_aes128ctr->init(ctx);
	if (!ctx->crypto_aes128ctr)
		exit_error(ctx, "Unable to initialize AES128-CTR implementation");
#endif

#ifdef USE_CRYPTO_GHASH
	ctx->crypto_ghash = ctx->conf->crypto_ghash->init(ctx);
	if (!ctx->crypto_ghash)
		exit_error(ctx, "Unable to initialize GHASH implementation");
#endif
}

static void crypto_free(fastd_context_t *ctx UNUSED) {
#ifdef USE_CRYPTO_AES128CTR
	ctx->conf->crypto_aes128ctr->free(ctx, ctx->crypto_aes128ctr);
	ctx->crypto_aes128ctr = NULL;
#endif

#ifdef USE_CRYPTO_GHASH
	ctx->conf->crypto_ghash->free(ctx, ctx->crypto_ghash);
	ctx->crypto_ghash = NULL;
#endif
}


static void init_sockets(fastd_context_t *ctx) {
	ctx->socks = malloc(ctx->conf->n_bind_addrs * sizeof(fastd_socket_t));

	unsigned i;
	fastd_bind_address_t *addr = ctx->conf->bind_addrs;
	for (i = 0; i < ctx->conf->n_bind_addrs; i++) {
		ctx->socks[i] = (fastd_socket_t){ .fd = -2, .addr = addr };

		if (addr == ctx->conf->bind_addr_default_v4)
			ctx->sock_default_v4 = &ctx->socks[i];

		if (addr == ctx->conf->bind_addr_default_v6)
			ctx->sock_default_v6 = &ctx->socks[i];

		addr = addr->next;
	}

	ctx->n_socks = ctx->conf->n_bind_addrs;
}


void fastd_setfd(const fastd_context_t *ctx, int fd, int set, int unset) {
	int flags = fcntl(fd, F_GETFD);
	if (flags < 0)
		exit_errno(ctx, "Getting file descriptor flags failed: fcntl");

	if (fcntl(fd, F_SETFD, (flags|set) & (~unset)) < 0)
		exit_errno(ctx, "Setting file descriptor flags failed: fcntl");
}

void fastd_setfl(const fastd_context_t *ctx, int fd, int set, int unset) {
	int flags = fcntl(fd, F_GETFL);
	if (flags < 0)
		exit_errno(ctx, "Getting file status flags failed: fcntl");

	if (fcntl(fd, F_SETFL, (flags|set) & (~unset)) < 0)
		exit_errno(ctx, "Setting file status flags failed: fcntl");
}

static void close_sockets(fastd_context_t *ctx) {
	unsigned i;
	for (i = 0; i < ctx->n_socks; i++)
		fastd_socket_close(ctx, &ctx->socks[i]);

	free(ctx->socks);
}

static inline void handle_forward(fastd_context_t *ctx, fastd_peer_t *source_peer, fastd_buffer_t buffer) {
	const fastd_eth_addr_t *dest_addr = fastd_get_dest_address(ctx, buffer);

	if (fastd_eth_addr_is_unicast(dest_addr)) {
		fastd_peer_t *dest_peer = fastd_peer_find_by_eth_addr(ctx, dest_addr);

		if (!dest_peer || dest_peer == source_peer || !fastd_peer_is_established(dest_peer)) {
			fastd_buffer_free(buffer);
			return;
		}

		ctx->conf->protocol->send(ctx, dest_peer, buffer);
	}
	else {
		fastd_send_all(ctx, source_peer, buffer);
	}
}

void fastd_handle_receive(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer) {
	if (ctx->conf->mode == MODE_TAP) {
		if (buffer.len < ETH_HLEN) {
			pr_debug(ctx, "received truncated packet");
			fastd_buffer_free(buffer);
			return;
		}

		const fastd_eth_addr_t *src_addr = fastd_get_source_address(ctx, buffer);

		if (fastd_eth_addr_is_unicast(src_addr))
			fastd_peer_eth_addr_add(ctx, peer, src_addr);
	}

	ctx->rx.packets++;
	ctx->rx.bytes += buffer.len;

	fastd_tuntap_write(ctx, buffer);

	if (ctx->conf->mode == MODE_TAP && ctx->conf->forward) {
		handle_forward(ctx, peer, buffer);
		return;
	}

	fastd_buffer_free(buffer);
}

static inline void on_pre_up(fastd_context_t *ctx) {
	if (!ctx->conf->on_pre_up)
		return;

	fastd_shell_exec(ctx, ctx->conf->on_pre_up, ctx->conf->on_pre_up_dir, NULL, NULL, NULL, NULL);
}

static inline void on_up(fastd_context_t *ctx) {
	if (!ctx->conf->on_up)
		return;

	fastd_shell_exec(ctx, ctx->conf->on_up, ctx->conf->on_up_dir, NULL, NULL, NULL, NULL);
}

static inline void on_down(fastd_context_t *ctx) {
	if (!ctx->conf->on_down)
		return;

	fastd_shell_exec(ctx, ctx->conf->on_down, ctx->conf->on_down_dir, NULL, NULL, NULL, NULL);
}

static inline void on_post_down(fastd_context_t *ctx) {
	if (!ctx->conf->on_post_down)
		return;

	fastd_shell_exec(ctx, ctx->conf->on_post_down, ctx->conf->on_post_down_dir, NULL, NULL, NULL, NULL);
}

static fastd_peer_group_t* init_peer_group(const fastd_peer_group_config_t *config, fastd_peer_group_t *parent) {
	fastd_peer_group_t *ret = calloc(1, sizeof(fastd_peer_group_t));

	ret->conf = config;
	ret->parent = parent;

	fastd_peer_group_t **children = &ret->children;
	fastd_peer_group_config_t *child_config;

	for (child_config = config->children; child_config; child_config = child_config->next) {
		*children = init_peer_group(child_config, ret);
		children = &(*children)->next;
	}

	return ret;
}

static void init_peer_groups(fastd_context_t *ctx) {
	ctx->peer_group = init_peer_group(ctx->conf->peer_group, NULL);
}

static void free_peer_group(fastd_peer_group_t *group) {
	while (group->children) {
		fastd_peer_group_t *child = group->children;
		group->children = group->children->next;

		free_peer_group(child);
	}

	free(group);
}

static void delete_peer_groups(fastd_context_t *ctx) {
	free_peer_group(ctx->peer_group);
}

static void init_peers(fastd_context_t *ctx) {
	fastd_peer_config_t *peer_conf;
	for (peer_conf = ctx->conf->peers; peer_conf; peer_conf = peer_conf->next)
		ctx->conf->protocol->peer_configure(ctx, peer_conf);

	for (peer_conf = ctx->conf->peers; peer_conf; peer_conf = peer_conf->next) {
		bool enable = ctx->conf->protocol->peer_check(ctx, peer_conf);

		if (enable && !peer_conf->enabled)
			fastd_peer_add(ctx, peer_conf);

		peer_conf->enabled = enable;
	}

	fastd_peer_t *peer, *next;
	for (peer = ctx->peers; peer; peer = next) {
		next = peer->next;

		if (peer->config) {
			if (!peer->config->enabled) {
				pr_info(ctx, "previously enabled peer %P disabled, deleting.", peer);
				fastd_peer_delete(ctx, peer);
			}
		}
		else {
			if (!ctx->conf->protocol->peer_check_temporary(ctx, peer))
				fastd_peer_delete(ctx, peer);
		}
	}
}

static void delete_peers(fastd_context_t *ctx) {
	fastd_peer_t *peer, *next;
	for (peer = ctx->peers; peer; peer = next) {
		next = peer->next;

		fastd_peer_delete(ctx, peer);
	}
}

static void dump_state(fastd_context_t *ctx) {
	pr_info(ctx, "TX stats: %U packet(s), %U byte(s); dropped: %U packet(s), %U byte(s); error: %U packet(s), %U byte(s)",
		ctx->tx.packets, ctx->tx.bytes, ctx->tx_dropped.packets, ctx->tx_dropped.bytes, ctx->tx_error.packets, ctx->tx_error.bytes);
	pr_info(ctx, "RX stats: %U packet(s), %U byte(s)", ctx->rx.packets, ctx->rx.bytes);

	pr_info(ctx, "dumping peers:");

	fastd_peer_t *peer;
	for (peer = ctx->peers; peer; peer = peer->next) {
		if (!fastd_peer_is_established(peer)) {
			pr_info(ctx, "peer %P not connected, address: %I", peer, &peer->address);
			continue;
		}

		if (ctx->conf->mode == MODE_TAP) {
			unsigned int eth_addresses = 0;
			size_t i;
			for (i = 0; i < ctx->n_eth_addr; i++) {
				if (ctx->eth_addr[i].peer == peer)
					eth_addresses++;
			}

			pr_info(ctx, "peer %P connected, address: %I, associated MAC addresses: %u", peer, &peer->address, eth_addresses);
		}
		else {
			pr_info(ctx, "peer %P connected, address: %I", peer, &peer->address);
		}
	}

	pr_info(ctx, "dump finished.");
}

static inline void update_time(fastd_context_t *ctx) {
	clock_gettime(CLOCK_MONOTONIC, &ctx->now);
}

static void send_handshake(fastd_context_t *ctx, fastd_peer_t *peer) {
	if (!fastd_peer_is_established(peer)) {
		if (!peer->next_remote)
			exit_bug(ctx, "send_handshake: no remote");

		fastd_peer_claim_address(ctx, peer, NULL, NULL, &peer->next_remote->address);
		fastd_peer_reset_socket(ctx, peer);
	}

	if (!peer->sock)
		return;

	if (peer->address.sa.sa_family == AF_UNSPEC) {
		pr_debug(ctx, "not sending a handshake to %P (no valid address resolved)", peer);
		return;
	}

	if (timespec_diff(&ctx->now, &peer->last_handshake) < (int)ctx->conf->min_handshake_interval*1000
	    && fastd_peer_address_equal(&peer->address, &peer->last_handshake_address)) {
		pr_debug(ctx, "not sending a handshake to %P as we sent one a short time ago", peer);
		return;
	}

	pr_debug(ctx, "sending handshake to %P[%I]...", peer, &peer->address);
	peer->last_handshake = ctx->now;
	peer->last_handshake_address = peer->address;
	ctx->conf->protocol->handshake_init(ctx, peer->sock, &peer->local_address, &peer->address, peer);
}

static void handle_handshake_queue(fastd_context_t *ctx) {
	if (!ctx->handshake_queue.next)
		return;

	fastd_peer_t *peer = container_of(ctx->handshake_queue.next, fastd_peer_t, handshake_entry);
	if (timespec_after(&peer->next_handshake, &ctx->now))
		return;

	fastd_peer_schedule_handshake_default(ctx, peer);

	if (!fastd_peer_may_connect(ctx, peer)) {
		peer->next_remote = peer->remotes;
		return;
	}

	send_handshake(ctx, peer);

	if (fastd_peer_is_established(peer))
		return;

	peer->next_remote = peer->next_remote->next;
	if (!peer->next_remote)
		peer->next_remote = peer->remotes;

	if (fastd_remote_is_dynamic(peer->next_remote))
		fastd_resolve_peer(ctx, peer, peer->next_remote);
}

static inline bool handle_tun_tap(fastd_context_t *ctx, fastd_buffer_t buffer) {
	if (ctx->conf->mode != MODE_TAP)
		return false;

	if (buffer.len < ETH_HLEN) {
		pr_debug(ctx, "truncated packet on tap interface");
		fastd_buffer_free(buffer);
		return true;
	}

	const fastd_eth_addr_t *dest_addr = fastd_get_dest_address(ctx, buffer);
	if (!fastd_eth_addr_is_unicast(dest_addr))
		return false;

	fastd_peer_t *peer = fastd_peer_find_by_eth_addr(ctx, dest_addr);

	if (!peer || !fastd_peer_is_established(peer)) {
		fastd_buffer_free(buffer);
		return true;
	}

	ctx->conf->protocol->send(ctx, peer, buffer);
	return true;
}

static void handle_tun(fastd_context_t *ctx) {
	fastd_buffer_t buffer = fastd_tuntap_read(ctx);
	if (!buffer.len)
		return;

	if (handle_tun_tap(ctx, buffer))
		return;

	/* TUN mode or multicast packet */
	fastd_send_all(ctx, NULL, buffer);
}

static void handle_resolve_returns(fastd_context_t *ctx) {
	fastd_resolve_return_t resolve_return;

	while (read(ctx->resolverfd, &resolve_return, sizeof(resolve_return)) < 0) {
		if (errno != EINTR)
			exit_errno(ctx, "handle_resolve_return: read");
	}

	fastd_peer_t *peer;
	for (peer = ctx->peers; peer; peer = peer->next) {
		if (!peer->config)
			continue;

		fastd_remote_t *remote;
		for (remote = peer->remotes; remote; remote = remote->next) {
			if (remote == resolve_return.remote)
				break;
		}

		if (!remote)
			continue;

		fastd_peer_handle_resolve(ctx, peer, remote, &resolve_return.addr);

		break;
	}

	fastd_remote_unref(resolve_return.remote);
}

static inline int handshake_timeout(fastd_context_t *ctx) {
	if (!ctx->handshake_queue.next)
		return -1;

       fastd_peer_t *peer = container_of(ctx->handshake_queue.next, fastd_peer_t, handshake_entry);

       int diff_msec = timespec_diff(&peer->next_handshake, &ctx->now);
       if (diff_msec < 0)
	       return 0;
       else
	       return diff_msec;
}

static void handle_input(fastd_context_t *ctx) {
	const size_t n_fds = 2 + ctx->n_socks + ctx->n_peers;
	struct pollfd fds[n_fds];
	fds[0].fd = ctx->tunfd;
	fds[0].events = POLLIN;
	fds[1].fd = ctx->resolverfd;
	fds[1].events = POLLIN;

	unsigned i;
	for (i = 2; i < ctx->n_socks+2; i++) {
		fds[i].fd = ctx->socks[i-2].fd;
		fds[i].events = POLLIN;
	}

	fastd_peer_t *peer;
	for (peer = ctx->peers; peer; peer = peer->next) {
		if (peer->sock && fastd_peer_is_socket_dynamic(peer))
			fds[i].fd = peer->sock->fd;
		else
			fds[i].fd = -1;

		fds[i].events = POLLIN;

		i++;
	}

	if (i != n_fds)
		exit_bug(ctx, "fd count mismatch");

	int keepalive_timeout = timespec_diff(&ctx->next_keepalives, &ctx->now);

	if (keepalive_timeout < 0)
		keepalive_timeout = 0;

	int timeout = handshake_timeout(ctx);
	if (timeout < 0 || timeout > keepalive_timeout)
		timeout = keepalive_timeout;

	int ret = poll(fds, n_fds, timeout);
	if (ret < 0) {
		if (errno == EINTR)
			return;

		exit_errno(ctx, "poll");
	}

	update_time(ctx);

	if (fds[0].revents & POLLIN)
		handle_tun(ctx);
	if (fds[1].revents & POLLIN)
		handle_resolve_returns(ctx);

	for (i = 2; i < ctx->n_socks+2; i++) {
		if (fds[i].revents & (POLLERR|POLLHUP|POLLNVAL))
			fastd_socket_error(ctx, &ctx->socks[i-2]);
		else if (fds[i].revents & POLLIN)
			fastd_receive(ctx, &ctx->socks[i-2]);
	}

	for (peer = ctx->peers; peer; peer = peer->next) {
		if (fds[i].revents & (POLLERR|POLLHUP|POLLNVAL))
			fastd_peer_reset_socket(ctx, peer);
		else if (fds[i].revents & POLLIN)
			fastd_receive(ctx, peer->sock);

		i++;
	}

	if (i != n_fds)
		exit_bug(ctx, "fd count mismatch");
}

static void cleanup_peers(fastd_context_t *ctx) {
	fastd_peer_t *peer, *next;

	for (peer = ctx->peers; peer; peer = next) {
		next = peer->next;

		if (fastd_peer_is_temporary(peer) || fastd_peer_is_established(peer)) {
			if (timespec_diff(&ctx->now, &peer->seen) > (int)ctx->conf->peer_stale_time*1000) {
				if (fastd_peer_is_temporary(peer)) {
					fastd_peer_delete(ctx, peer);
				}
				else {
					fastd_peer_reset(ctx, peer);
				}
			}
		}
	}
}

static void maintenance(fastd_context_t *ctx) {
	while (ctx->peers_temp) {
		fastd_peer_t *peer = ctx->peers_temp;
		ctx->peers_temp = ctx->peers_temp->next;

		fastd_peer_enable_temporary(ctx, peer);
	}

	cleanup_peers(ctx);
	fastd_peer_eth_addr_cleanup(ctx);

	fastd_socket_handle_binds(ctx);

	if (timespec_after(&ctx->now, &ctx->next_keepalives)) {
		fastd_peer_t *peer;
		for (peer = ctx->peers; peer; peer = peer->next) {
			if (!fastd_peer_is_established(peer))
				continue;

			if (timespec_diff(&ctx->now, &peer->last_send) < (int)ctx->conf->keepalive_timeout*1000)
				continue;

			pr_debug2(ctx, "sending keepalive to %P", peer);
			ctx->conf->protocol->send(ctx, peer, fastd_buffer_alloc(ctx, 0, ctx->conf->min_encrypt_head_space, ctx->conf->min_encrypt_tail_space));
		}

		ctx->next_keepalives.tv_sec += ctx->conf->keepalive_interval;
	}
}


static void close_fds(fastd_context_t *ctx) {
	struct rlimit rl;
	int fd, maxfd;

	if (getrlimit(RLIMIT_NOFILE, &rl) > 0)
		maxfd = (int)rl.rlim_max;
	else
		maxfd = sysconf(_SC_OPEN_MAX);

	for (fd = 3; fd < maxfd; fd++) {
		if (close(fd) < 0) {
			if (errno == EINTR) {
				fd--;
				continue;
			}

			if (errno != EBADF)
				pr_error_errno(ctx, "close");
		}
	}
}

static void write_pid(fastd_context_t *ctx, pid_t pid) {
	if (!ctx->conf->pid_file)
		return;

	uid_t uid = geteuid();
	gid_t gid = getegid();

	if (ctx->conf->user || ctx->conf->group) {
		if (setegid(ctx->conf->gid) < 0)
			pr_debug_errno(ctx, "setegid");
		if (seteuid(ctx->conf->uid) < 0)
			pr_debug_errno(ctx, "seteuid");
	}

	int fd = open(ctx->conf->pid_file, O_WRONLY|O_CREAT|O_TRUNC, 0666);
	if (fd < 0) {
		pr_error_errno(ctx, "can't write PID file: open");
		goto end;
	}

	if (dprintf(fd, "%i", pid) < 0)
		pr_error_errno(ctx, "can't write PID file: dprintf");

	if (close(fd) < 0)
		pr_warn_errno(ctx, "close");

 end:
	if (seteuid(uid) < 0)
		pr_debug_errno(ctx, "seteuid");
	if (setegid(gid) < 0)
		pr_debug_errno(ctx, "setegid");
}

static void set_user(fastd_context_t *ctx) {
	if (chdir("/"))
		pr_error(ctx, "can't chdir to `/': %s", strerror(errno));

	if (ctx->conf->user || ctx->conf->group) {
		if (setgid(ctx->conf->gid) < 0)
			exit_errno(ctx, "setgid");

		if (setuid(ctx->conf->uid) < 0)
			exit_errno(ctx, "setuid");

		pr_info(ctx, "Changed to UID %i, GID %i.", ctx->conf->uid, ctx->conf->gid);
	}
}

static void set_groups(fastd_context_t *ctx) {
	if (ctx->conf->groups) {
		if (setgroups(ctx->conf->n_groups, ctx->conf->groups) < 0) {
			if (errno != EPERM)
				pr_debug_errno(ctx, "setgroups");
		}
	}
	else if (ctx->conf->user || ctx->conf->group) {
		if (setgroups(1, &ctx->conf->gid) < 0) {
			if (errno != EPERM)
				pr_debug_errno(ctx, "setgroups");
		}
	}
}

static void drop_caps(fastd_context_t *ctx) {
	set_user(ctx);
	fastd_cap_drop(ctx);
}

int main(int argc, char *argv[]) {
	fastd_context_t ctx = {};

	close_fds(&ctx);

	fastd_random_bytes(&ctx, &ctx.randseed, sizeof(ctx.randseed), false);

	init_pipes(&ctx);

	fastd_config_t conf;
	fastd_configure(&ctx, &conf, argc, argv);

	init_log(&ctx);

	if (conf.generate_key) {
		conf.protocol->generate_key(&ctx);
		exit(0);
	}

	init_signals(&ctx);

	conf.protocol_config = conf.protocol->init(&ctx);

	if (conf.show_key) {
		conf.protocol->show_key(&ctx);
		exit(0);
	}

	update_time(&ctx);

	conf.long_ago = ctx.now;
	conf.long_ago.tv_sec -= 86400; /* 24h in the past */

	ctx.next_keepalives = ctx.now;
	ctx.next_keepalives.tv_sec += conf.keepalive_interval;

	pr_info(&ctx, "fastd " FASTD_VERSION " starting");

	fastd_cap_init(&ctx);

	/* change groups early as the can be relevant for file access (for PID file & log files) */
	set_groups(&ctx);

	crypto_init(&ctx);

	init_sockets(&ctx);

	if (!fastd_socket_handle_binds(&ctx))
		exit_error(&ctx, "unable to bind default socket");

	on_pre_up(&ctx);

	fastd_tuntap_open(&ctx);

	init_peer_groups(&ctx);
	if (conf.daemon) {
		pid_t pid = fork();
		if (pid < 0) {
			exit_errno(&ctx, "fork");
		}
		else if (pid > 0) {
			write_pid(&ctx, pid);
			exit(0);
		}

		if (setsid() < 0)
			pr_error_errno(&ctx, "setsid");
	}
	else {
		write_pid(&ctx, getpid());
	}

	if (conf.drop_caps == DROP_CAPS_EARLY)
		drop_caps(&ctx);

	on_up(&ctx);

	if (conf.drop_caps == DROP_CAPS_ON)
		drop_caps(&ctx);
	else if (conf.drop_caps == DROP_CAPS_OFF)
		set_user(&ctx);

	fastd_config_load_peer_dirs(&ctx, &conf);
	init_peers(&ctx);

	while (!terminate) {
		handle_handshake_queue(&ctx);

		handle_input(&ctx);

		maintenance(&ctx);

		sigset_t set, oldset;
		sigemptyset(&set);
		pthread_sigmask(SIG_SETMASK, &set, &oldset);

		if (sighup) {
			sighup = false;

			pr_info(&ctx, "reconfigure triggered");

			close_log(&ctx);
			init_log(&ctx);

			fastd_config_load_peer_dirs(&ctx, &conf);
			init_peers(&ctx);
		}

		if (dump) {
			dump = false;
			dump_state(&ctx);
		}

		pthread_sigmask(SIG_SETMASK, &oldset, NULL);
	}

	on_down(&ctx);

	delete_peers(&ctx);
	delete_peer_groups(&ctx);

	fastd_tuntap_close(&ctx);
	close_sockets(&ctx);

	on_post_down(&ctx);

	free(ctx.protocol_state);
	free(ctx.eth_addr);
	free(ctx.ifname);

	crypto_free(&ctx);

	close_log(&ctx);
	fastd_config_release(&ctx, &conf);

	return 0;
}