aprsc/src/aprsc.c

/*
 *	aprsc
 *
 *	(c) Heikki Hannikainen, OH7LZB <hessu@hes.iki.fi>
 *
 *	This program is licensed under the BSD license, which can be found
 *	in the file LICENSE.
 *	
 */

#define HELPS	"Usage: aprsc [-t <chrootdir>] [-u <setuid user>] [-c <cfgfile>] [-f (fork)]\n" \
	" [-n <logname>] [-e <loglevel>] [-o <logdest>] [-r <logdir>]\n" \
	" [-y (try config)] [-h (help)]\n"

#include <pthread.h>
#include <semaphore.h>

#include <string.h>
#include <errno.h>
#include <stdarg.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pwd.h>
#include <time.h>
#include <sys/time.h>
#ifdef __linux__ /* Very Linux-specific code.. */
#include <sys/syscall.h>
#endif
#include <sys/resource.h>
#include <locale.h>
#include <ctype.h>

#include "hmalloc.h"
#include "hlog.h"
#include "config.h"
#include "accept.h"
#include "uplink.h"
#include "worker.h"
#include "status.h"
#include "http.h"
#include "version.h"

#include "dupecheck.h"
#include "filter.h"
#include "historydb.h"
#include "client_heard.h"
#include "keyhash.h"

#ifdef USE_POSIX_CAP
#include <sys/capability.h>
#include <sys/prctl.h>
#endif

struct itimerval itv; // Linux profiling timer does not pass over to pthreads..

int shutting_down;		// are we shutting down now?
int reopen_logs;		// should we reopen log files now?
int reconfiguring;		// should we reconfigure now?
int fileno_limit = -1;
int dbdump_at_exit;
int quit_after_config;
int liveupgrade_startup;
int liveupgrade_fired;
int want_dbdump;

/* random instance ID, alphanumeric low-case */
#define INSTANCE_ID_LEN 8
char instance_id[INSTANCE_ID_LEN+1];

pthread_attr_t pthr_attrs;

/*
 *	Parse arguments
 */

void parse_cmdline(int argc, char *argv[])
{
	int s, i;
	int failed = 0;
	
	while ((s = getopt(argc, argv, "c:ft:u:n:r:d:DyZe:o:?h")) != -1) {
	switch (s) {
		case 'c':
			if (cfgfile && cfgfile != def_cfgfile)
				hfree(cfgfile);
			cfgfile = hstrdup(optarg);
			break;
		case 'f':
			fork_a_daemon = 1;
			break;
		case 't':
			if (chrootdir)
				hfree(chrootdir);
			chrootdir = hstrdup(optarg);
			break;
		case 'u':
			if (setuid_s)
				hfree(setuid_s);
			setuid_s = hstrdup(optarg);
			break;
		case 'n':
			if (logname && logname != def_logname)
				hfree(logname);
			logname = hstrdup(optarg);
			break;
		case 'r':
			if (log_dir)
				hfree(log_dir);
			log_dir = hstrdup(optarg);
			break;
		case 'd':
			if (!strcasecmp(optarg, "requests")) {
				//dump_requests = 1;
			} else if (!strcasecmp(optarg, "splay")) {
				dump_splay = 1;
			} else {
				fprintf(stderr, "Unknown -d parameter: %s\n", optarg);
				failed = 1;
			}
			break;
		case 'D':
			dbdump_at_exit = 1;
			break;
		case 'y':
			quit_after_config = 1;
			break;
		case 'Z':
			liveupgrade_startup = 1;
			break;
		case 'e':
			i = pick_loglevel(optarg, log_levelnames);
			if (i > -1)
				log_level = i;
			else {
				fprintf(stderr, "Log level unknown: \"%s\"\n", optarg);
				failed = 1;
			}
			break;
		case 'o':
			i = pick_loglevel(optarg, log_destnames);
			if (i > -1)
				log_dest = 1 << (i-1);
			else {
				fprintf(stderr, "Log destination unknown: \"%s\"\n", optarg);
				failed = 1;
			}
			break;
		case '?':
		case 'h':
			fprintf(stderr, "%s\n", verstr);
			failed = 1;
	}
	}
	
	/* when doing a live upgrade, we're already with the right user */
	if (liveupgrade_startup && setuid_s) {
		hfree(setuid_s);
		setuid_s = NULL;
	}
	
	if ((log_dest == L_FILE) && (!log_dir)) {
		fprintf(stderr, "Log destination set to 'file' but no log directory specified!\n");
		failed = 1;
	}
	
	if (failed) {
		fputs(HELPS, stderr);
		exit(failed);
	}
	
	if (quit_after_config) {
		fork_a_daemon = 0;
	}
}

/*
 *	signal handler
 */
 
int sighandler(int signum)
{
	switch (signum) {

	case SIGINT:
	case SIGTERM:
	case SIGQUIT:
		hlog(LOG_NOTICE, "Shutting down on signal %d", signum);
		shutting_down = 1;
		return 0;
		
	case SIGHUP:
		hlog(LOG_INFO, "SIGHUP received: reopening logs");
		reopen_logs = 1;
		break;
		
	case SIGUSR1:
		hlog(LOG_INFO, "SIGUSR1 received: reconfiguring");
		reconfiguring = 1;
		break;
		
	case SIGUSR2:
		hlog(LOG_INFO, "SIGUSR2 received: performing live upgrade");
		liveupgrade_fired = 1;
		shutting_down = 1;
		break;
		
	default:
		hlog(LOG_WARNING, "* SIG %d ignored", signum);
		break;
	}
	
	signal(signum, (void *)sighandler);	/* restore handler */
	return 0;
		
}

/*
 *	A very Linux specific thing, as there the pthreads are a special variation
 *	of fork(), and per POSIX the profiling timers are not kept over fork()...
 */
void pthreads_profiling_reset(const char *name)
{
#ifdef __linux__ /* Very Linux-specific code.. */
	int tid;
	if (itv.it_interval.tv_usec || itv.it_interval.tv_sec) {
	  setitimer(ITIMER_PROF, &itv, NULL);
	}

	tid = syscall(SYS_gettid);
	hlog(LOG_DEBUG, "Thread %s: Linux ThreadId: %d", name, tid);
#endif
}

#define PATHLEN 500
static void dbdump_historydb(void)
{
	FILE *fp;
	char path[PATHLEN+1];
	
	snprintf(path, PATHLEN, "%s/historydb.json", rundir);
	fp = fopen(path,"w");
	if (fp) {
		historydb_dump(fp);
		fclose(fp);
	}
}

static void dbdump_all(void)
{
	FILE *fp;
	char path[PATHLEN+1];

	/*
	 *    As a general rule, dumping of databases is not a Good Idea in
	 *    operational system.  Development time debugging on other hand..
	 */
	 
	dbdump_historydb();
	
	snprintf(path, PATHLEN, "%s/filter.wx.dump", rundir);
	fp = fopen(path,"w");
	if (fp) {
		filter_wx_dump(fp);
		fclose(fp);
	}
	snprintf(path, PATHLEN, "%s/filter.entry.dump", rundir);
	fp = fopen(path,"w");
	if (fp) {
		filter_entrycall_dump(fp);
		fclose(fp);
	}
	snprintf(path, PATHLEN, "%s/pbuf.dump", rundir);
	fp = fopen(path,"w");
	if (fp) {
		pbuf_dump(fp);
		fclose(fp);
	}
	snprintf(path, PATHLEN, "%s/pbuf.dupe.dump", rundir);
	fp = fopen(path,"w");
	if (fp) {
		pbuf_dupe_dump(fp);
		fclose(fp);
	}
}

static void dbload_all(void)
{
	FILE *fp;
	char path[PATHLEN+1];
	char path_renamed[PATHLEN+1];
	
	snprintf(path, PATHLEN, "%s/historydb.json", rundir);
	fp = fopen(path,"r");
	if (fp) {
		hlog(LOG_INFO, "Live upgrade: Loading historydb from %s ...", path);
		snprintf(path_renamed, PATHLEN, "%s/historydb.json.old", rundir);
		if (rename(path, path_renamed) < 0) {
			hlog(LOG_ERR, "Failed to rename historydb dump file %s to %s: %s",
				path, path_renamed, strerror(errno));
			unlink(path);
		}
		
		historydb_load(fp);
		fclose(fp);
	}
}

/*
 *	switch uid
 */
struct passwd pwbuf;
char *pw_buf_s;

/* Look up the target UID/GID from passwd/group */
static void find_uid(const char *uid_s)
{
	struct passwd *pwbufp;
	int buflen;
	
	buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
	if (buflen < 10)
		buflen = 1024;
	
	pw_buf_s = hmalloc(buflen);
	
#ifdef sun
	pwbufp = getpwnam_r(uid_s, &pwbuf, pw_buf_s, buflen);
#else
	int e = getpwnam_r(uid_s, &pwbuf, pw_buf_s, buflen, &pwbufp);
	
	if (e) {
		fprintf(stderr, "aprsc: getpwnam(%s) failed, can not set UID: %s\n", uid_s, strerror(e));
		exit(1);
	}
#endif
	
	if (pwbufp == NULL) {
		fprintf(stderr, "aprsc: getpwnam(%s) failed, can not set UID: user not found\n", uid_s);
		exit(1);
	}
}

/* set effective UID, for startup time */
static void set_euid(void)
{
	if (setegid(pwbuf.pw_gid)) {
		fprintf(stderr, "aprsc: Failed to set effective GID %d: %s\n", pwbuf.pw_gid, strerror(errno));
		exit(1);
	}
	
	if (seteuid(pwbuf.pw_uid)) {
		fprintf(stderr, "aprsc: Failed to set effective UID %d: %s\n", pwbuf.pw_uid, strerror(errno));
		exit(1);
	}
}

/* switch back to uid 0 for post-config setup as root */
static void set_euid_0(void)
{
	if (seteuid(0)) {
		fprintf(stderr, "aprsc: Failed to set effective UID back to 0: %s\n", strerror(errno));
		exit(1);
	}
}

static void check_caps(char *when)
{
#ifdef USE_POSIX_CAP
	cap_t caps = cap_get_proc();
	
	if (caps == NULL) {
		hlog(LOG_ERR, "check_caps: Failed to get current POSIX capabilities: %s", strerror(errno));
		return;
	}
	
	char *s = cap_to_text(caps, NULL);
	
	if (s) {
		hlog(LOG_DEBUG, "aprsc: capabilities %s: %s", when, s);
	}
	
	cap_free(caps);
#endif
}

static int set_initial_capabilities(void)
{
#ifdef USE_POSIX_CAP
	int ret = -1;
	
	cap_t caps = cap_init();

	/* list of capabilities needed at startup - less than what root has */
#define NCAPS 5
	cap_value_t cap_list[NCAPS];
	cap_list[0] = CAP_NET_BIND_SERVICE;
	cap_list[1] = CAP_SETUID;
	cap_list[2] = CAP_SETGID;
	cap_list[3] = CAP_SYS_RESOURCE;
	cap_list[4] = CAP_SYS_CHROOT;
	
	if (cap_set_flag(caps, CAP_PERMITTED, NCAPS, cap_list, CAP_SET) == -1) {
		fprintf(stderr, "aprsc: Failed to set initial POSIX capability flags: %s\n", strerror(errno));
		goto end_caps;
	}
	
	if (cap_set_flag(caps, CAP_EFFECTIVE, NCAPS, cap_list, CAP_SET) == -1) {
		fprintf(stderr, "aprsc: Failed to set initial POSIX capability flags: %s\n", strerror(errno));
		goto end_caps;
	}
	
	//fprintf(stderr, "aprsc: going to set: %s\n", cap_to_text(caps, NULL));
	
	if (cap_set_proc(caps) == -1) {
		fprintf(stderr, "aprsc: Failed to apply initial POSIX capabilities: %s\n", strerror(errno));
		goto end_caps;
	}
	
	if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == -1) {
		fprintf(stderr, "aprsc: Failed to set PR_SET_KEEPCAPS: %s\n", strerror(errno));
		goto end_caps;
	}
	
	//fprintf(stderr, "aprsc: Successfully enabled initial POSIX capabilities\n");
	ret = 0;
	
end_caps:
	if (caps) {
		if (cap_free(caps) == -1)
			fprintf(stderr, "aprsc: Failed to free capabilities: %s\n", strerror(errno));
		caps = NULL;
	}
	
	return ret;
#else
	return 0;
#endif
}

static int set_final_capabilities(void)
{
#ifdef USE_POSIX_CAP
	int ret = -1;
	cap_t caps = cap_init();

#define NCAPS_FINAL 1
	if (listen_low_ports) {
		cap_value_t cap_list[NCAPS_FINAL];
		cap_list[0] = CAP_NET_BIND_SERVICE;
		
		if (cap_set_flag(caps, CAP_PERMITTED, NCAPS_FINAL, cap_list, CAP_SET) == -1) {
			hlog(LOG_ERR, "aprsc: Failed to set final permitted POSIX capability flags: %s", strerror(errno));
			goto end_caps;
		}
		
		if (cap_set_flag(caps, CAP_EFFECTIVE, NCAPS_FINAL, cap_list, CAP_SET) == -1) {
			hlog(LOG_ERR, "aprsc: Failed to set final effective POSIX capability flags: %s", strerror(errno));
			goto end_caps;
		}
		
		/* when we exec() myself in live upgrade, these capabilities are also
		 * needed by the new process. INHERITABLE FTW!
		 */
		if (cap_set_flag(caps, CAP_INHERITABLE, NCAPS_FINAL, cap_list, CAP_SET) == -1) {
			hlog(LOG_ERR, "aprsc: Failed to set final inheritable POSIX capability flags: %s", strerror(errno));
			goto end_caps;
		}
		
		//fprintf(stderr, "aprsc: going to set: %s\n", cap_to_text(caps, NULL));
		ret = 1;
	} else {
		ret = 0;
	}
	
	if (cap_set_proc(caps) == -1) {
		hlog(LOG_ERR, "aprsc: Failed to apply final POSIX capabilities: %s", strerror(errno));
		ret = -1;
		goto end_caps;
	}
	
	//fprintf(stderr, "aprsc: Successfully enabled final POSIX capabilities\n");
	
end_caps:
	if (caps) {
		if (cap_free(caps) == -1)
			hlog(LOG_ERR, "aprsc: Failed to free capabilities: %s", strerror(errno));
		caps = NULL;
	}
	
	return ret;
#else
	return -1;
#endif
}

/* set real UID to non-root, cannot be reversed */
static void set_uid(void)
{
	//check_caps("before set_uid");
	
	if (setgid(pwbuf.pw_gid)) {
		fprintf(stderr, "aprsc: Failed to set GID %d: %s\n", pwbuf.pw_gid, strerror(errno));
		exit(1);
	}
	
	if (setuid(pwbuf.pw_uid)) {
		fprintf(stderr, "aprsc: Failed to set UID %d: %s\n", pwbuf.pw_uid, strerror(errno));
		exit(1);
	}
	
}

/*
 *	Check that we're not running as root. Bail out if we are
 */

static void check_uid(void)
{
	if (getuid() == 0 || geteuid() == 0) {
		fprintf(stderr,
			"aprsc: Security incident about to happen: running as root.\n"
			"Use the -u <username> switch to run as unprivileged user 'aprsc', or start\n"
			"it up as such an user.\n");
		exit(1);
	}
}

/*
 *	Generate a pseudorandom instance ID by reading the pseudorandom
 *	source and converting the binary data to lower-case alphanumeric
 */

static void generate_instance_id(void)
{
	unsigned char s[INSTANCE_ID_LEN];
	int fd, l;
	char c;
	unsigned seed;
	struct timeval tv;
	
	if ((fd = open("/dev/urandom", O_RDONLY)) == -1) {
		hlog(LOG_ERR, "open(/dev/urandom) failed: %s", strerror(errno));
		fd = -1;
	}
	
	/* seed the prng */
	if (fd >= 0) {
		l = read(fd, &seed, sizeof(seed));
		if (l != sizeof(seed)) {
			hlog(LOG_ERR, "read(/dev/urandom, %d) for seed failed: %s", sizeof(seed), strerror(errno));
			close(fd);
			fd = -1;
		}
	}
	
	if (fd < 0) {
		/* not very strong, but we're not doing cryptography here */
		gettimeofday(&tv, NULL);
		seed = tv.tv_sec + tv.tv_usec + getpid();
	}
	
	srandom(seed);
	
	if (fd >= 0) {
		/* generate instance id */
		l = read(fd, s, INSTANCE_ID_LEN);
		if (l != INSTANCE_ID_LEN) {
			hlog(LOG_ERR, "read(/dev/urandom, %d) failed: %s", INSTANCE_ID_LEN, strerror(errno));
			close(fd);
			fd = -1;
		}
	}
	
	if (fd < 0) {
		/* urandom failed for us, use something inferior */
		for (l = 0; l < INSTANCE_ID_LEN; l++)
			s[l] = random() % 256;
	}
	
	for (l = 0; l < INSTANCE_ID_LEN; l++) {
		/* 256 is not divisible by 36, the distribution is slightly skewed,
		 * but that's not serious.
		 */
		c = s[l] % (26 + 10); /* letters and numbers */
		if (c < 10)
			c += 48; /* number */
		else
			c = c - 10 + 97; /* letter */
		instance_id[l] = c;
	}
	instance_id[INSTANCE_ID_LEN] = 0;
	
	if (fd >= 0)
		close(fd);
}

/*
 *	Preload resolver libraries before performing a chroot,
 *	so that we won't need copies of the .so files within the
 *	chroot.
 *
 *	This is done by doing a DNS lookup which "accidentally"
 *	phones home with the version information.
 *
 *	Tin foil hats off. Version information and instance statistics
 *	make developers happy.
 */

void version_report(const char *state)
{
	struct addrinfo hints;
	struct addrinfo *ai;
	char v[80];
	char n[32];
	char s[300];
	int i, l;
	
	/* don't send version reports during testing */
	if (getenv("APRSC_NO_VERSION_REPORT"))
		return;
	
	/* normalize version string to fit in a DNS label */
	strncpy(v, version_build, sizeof(v));
	l = strlen(v);
	for (i = 0; i < sizeof(v) && i < l; i++)
		if (!isalnum(v[i]))
			v[i] = '-';
	
	if (serverid) {
		/* we're configured, include serverid and normalize it */
		strncpy(n, serverid, sizeof(n));
		n[sizeof(n)-1] = 0;
		l = strlen(n);
		for (i = 0; i < sizeof(n) && i < l; i++)
			if (!isalnum(n[i]))
				n[i] = '-';
		snprintf(s, 300, "%s.%s.%s.%s.aprsc.he.fi", n, v, instance_id, state);
	} else {
		snprintf(s, 300, "%s.%s.%s.aprsc.he.fi", v, instance_id, state);
	}
	
	/* reduce the amount of lookups in case of a failure, don't do
	 * separate AAAA + A lookups
	 */
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_INET;
	
	ai = NULL;
	i = getaddrinfo(s, NULL, &hints, &ai);
	if (i != 0)
		hlog(LOG_INFO, "DNS lookup of aprsc.he.fi failed: %s", gai_strerror(i));
	if (ai)
		freeaddrinfo(ai);
}

/*
 *	Execute a new myself to perform a live upgrade
 */

static void liveupgrade_exec(int argc, char **argv)
{
	char **nargv;
	int i;
	int need_live_flag = 1;
	char *bin = argv[0];
	
	i = strlen(argv[0]);
	if (chrootdir && strncmp(argv[0], chrootdir, strlen(chrootdir)) == 0) {
		bin = hmalloc(i+1);
		strncpy(bin, argv[0] + strlen(chrootdir), i);
	}
	
	hlog(LOG_NOTICE, "Live upgrade: Executing the new me: %s", bin);
	
	/* generate argument list for the new executable, it should be appended with
	 * -Z (live upgrade startup flag) unless it's there already
	 */
	nargv = hmalloc(sizeof(char *) * (argc+2));
	
	for (i = 0; i < argc; i++) {
		if (i == 0)
			nargv[i] = bin;
		else
			nargv[i] = argv[i];
		
		/* check if the live upgrade flag is already present */
		if (strcmp(argv[i], "-Z") == 0)
			need_live_flag = 0;
	}
	
	if (need_live_flag)
		nargv[i++] = hstrdup("-Z");
		
	nargv[i++] = NULL;
	
	/* close pid file and free the lock on it */
	closepid();
	
	/* close log file so that we don't leak the file descriptor */
	close_log(0);
	
	/* execute new binary, should not return if all goes fine */
	execv(bin, nargv);
	
	hlog(LOG_CRIT, "liveupgrade: exec failed, I'm still here! %s", strerror(errno));
	
	/* free resources in case we'd decide to continue anyway */
	if (bin != argv[0])
		hfree(bin);
	if (need_live_flag)
		hfree(nargv[i-1]);
	hfree(nargv);
}


/*
 *	Time-keeping thread
 */

#ifdef USE_CLOCK_GETTIME
static double timeval_diff(struct timespec start, struct timespec end)
{
	double diff;
	
	diff = (end.tv_sec - start.tv_sec)
		+ ((end.tv_nsec - start.tv_nsec) / 1000000000.0);
	
	return diff;
}
#else
static double timeval_diff(struct timeval start, struct timeval end)
{
	double diff;
	
	diff = (end.tv_sec - start.tv_sec)
		+ ((end.tv_usec - start.tv_usec) / 1000000.0);
	
	return diff;
}
#endif

void time_set_tick_and_now(void)
{
#ifdef USE_CLOCK_GETTIME
	struct timespec ts;
	clock_gettime(CLOCK_MONOTONIC, &ts);
	tick = ts.tv_sec;
	clock_gettime(CLOCK_REALTIME, &ts);
	now = ts.tv_sec;
#else
	struct timeval tv;
	gettimeofday(&tv, NULL);
	tick = tv.tv_sec;
	now = tv.tv_sec;
#endif
}

void time_thread(void *asdf)
{
	sigset_t sigs_to_block;
	time_t previous_tick;
	struct timespec sleep_req;
#ifdef USE_CLOCK_GETTIME
	struct timespec sleep_start, sleep_end;
	struct timespec ts;
	hlog(LOG_INFO, "Time thread starting: using clock_gettime");
#else
	struct timeval sleep_start, sleep_end;
	hlog(LOG_INFO, "Time thread starting: using gettimeofday");
#endif

	pthreads_profiling_reset("time");
	
	sigemptyset(&sigs_to_block);
	sigaddset(&sigs_to_block, SIGALRM);
	sigaddset(&sigs_to_block, SIGINT);
	sigaddset(&sigs_to_block, SIGTERM);
	sigaddset(&sigs_to_block, SIGQUIT);
	sigaddset(&sigs_to_block, SIGHUP);
	sigaddset(&sigs_to_block, SIGURG);
	sigaddset(&sigs_to_block, SIGPIPE);
	sigaddset(&sigs_to_block, SIGUSR1);
	sigaddset(&sigs_to_block, SIGUSR2);
	pthread_sigmask(SIG_BLOCK, &sigs_to_block, NULL);
	
	time_set_tick_and_now();
	previous_tick = tick;
	
	sleep_req.tv_sec = 0;
	sleep_req.tv_nsec = 210 * 1000 * 1000; /* 210 ms */
	
	while (!accept_shutting_down) {
#ifdef USE_CLOCK_GETTIME
		clock_gettime(CLOCK_MONOTONIC, &sleep_start);
		nanosleep(&sleep_req, NULL);
		clock_gettime(CLOCK_MONOTONIC, &sleep_end);
		tick = sleep_end.tv_sec;
		clock_gettime(CLOCK_REALTIME, &ts);
		now = ts.tv_sec;
#else
		gettimeofday(&sleep_start, NULL);
		nanosleep(&sleep_req, NULL);
		gettimeofday(&sleep_end, NULL);
		tick = sleep_end.tv_sec;
		now = tick;
#endif
		
		double slept = timeval_diff(sleep_start, sleep_end);
		if (slept > 0.90)
			hlog(LOG_WARNING, "time keeping: sleep of %d ms took %.6f s!", sleep_req.tv_nsec / 1000 / 1000, slept);
		
		/* catch some oddities with time keeping */
		if (tick != previous_tick) {
			if (previous_tick > tick) {
				hlog(LOG_WARNING, "time keeping: Time jumped backward by %d seconds!", previous_tick - tick);
			} else if (previous_tick < tick-1) {
				hlog(LOG_WARNING, "time keeping: Time jumped forward by %d seconds!", tick - previous_tick);
			}
			
			previous_tick = tick;
		}
		
	}
	
}	

static void init_reopen_stdio(void)
{
	/* close stdin and stdout, and any other FDs that might be left open */
	/* closing stderr masks error logs between this point and opening the logs... suboptimal. */
	{
		int i;
		close(0);
		close(1);
		for (i = 3; i < 100; i++)
			close(i);
	}
	
	/* all of this fails in chroot, so do it before */
	if (open("/dev/null", O_RDWR) == -1) /* stdin */
		hlog(LOG_ERR, "open(/dev/null) failed for stdin: %s", strerror(errno));
	if (dup(0) == -1) /* stdout */
		hlog(LOG_ERR, "dup(0) failed for stdout: %s", strerror(errno));
}

/*
 *	Main
 */

int main(int argc, char **argv)
{
	pthread_t accept_th;
	pthread_t http_th;
	pthread_t time_th;
	int e;
	struct rlimit rlim;
	time_t cleanup_tick = 0;
	time_t version_tick = 0;
	int have_low_ports = 0;
	
	if (getuid() == 0)
		set_initial_capabilities();
	
	time_set_tick_and_now();
	cleanup_tick = tick;
	version_tick = tick + random() % 60; /* some load distribution */
	startup_tick = tick;
	startup_time = now;
	setlinebuf(stderr);
	
	/* set locale to C so that isalnum(), isupper() etc don't do anything
	 * unexpected if the environment is unexpected.
	 */
	if (!setlocale(LC_COLLATE, "C")) {
		hlog(LOG_CRIT, "Failed to set locale C for LC_COLLATE.");
		exit(1);
	}
	if (!setlocale(LC_CTYPE, "C")) {
		hlog(LOG_CRIT, "Failed to set locale C for LC_CTYPE.");
		exit(1);
	}
	if (!setlocale(LC_MESSAGES, "C")) {
		hlog(LOG_CRIT, "Failed to set locale C for LC_MESSAGES.");
		exit(1);
	}
	if (!setlocale(LC_NUMERIC, "C")) {
		hlog(LOG_CRIT, "Failed to set locale C for LC_NUMERIC.");
		exit(1);
	}

	/* Adjust process global fileno limit to match the maximum available
	 * at this time
	 */
	e = getrlimit(RLIMIT_NOFILE, &rlim);
	if (e < 0) {
		hlog(LOG_ERR, "Failed to get initial file number resource limit: %s", strerror(errno));
	} else {
		rlim.rlim_cur = rlim.rlim_max;
		e = setrlimit(RLIMIT_NOFILE, &rlim);
		e = getrlimit(RLIMIT_NOFILE, &rlim);
		fileno_limit = rlim.rlim_cur;
	}

	getitimer(ITIMER_PROF, &itv);
	
	/* command line */
	parse_cmdline(argc, argv);
	
	/* if setuid is needed, find the user UID */
	if (setuid_s)
		find_uid(setuid_s);
	
	/* fork a daemon */
	if (fork_a_daemon) {
		hlog(LOG_INFO, "Forking...");
		int i = fork();
		if (i < 0) {
			hlog(LOG_CRIT, "Fork to background failed: %s", strerror(errno));
			fprintf(stderr, "Fork to background failed: %s\n", strerror(errno));
			exit(1);
		} else if (i == 0) {
			/* child */
			hlog(LOG_INFO, "Child started...");
			if (setsid() == -1) {
				fprintf(stderr, "setsid() failed: %s\n", strerror(errno));
				//exit(1);
			}
		} else {
			/* parent, quitting */
			hlog(LOG_DEBUG, "Forked daemon process %d, parent quitting", i);
			exit(0);
		}
	}
	
	/* close stdin and stdout, and any other FDs that might be left open */
	if (!liveupgrade_startup)
		init_reopen_stdio();
		
	/* prepare for a possible chroot, force loading of
	 * resolver libraries at this point, so that we don't
	 * need a copy of the shared libs within the chroot dir
	 */
	generate_instance_id();
	version_report("startup");
	
	/* do a chroot if required */
	if (chrootdir && !liveupgrade_startup) {
		if ((!setuid_s) || pwbuf.pw_uid == 0) {
			fprintf(stderr, "aprsc: chroot requested but not setuid to non-root user - insecure\n"
				"configuration detected. Using -u <username> and start as root required.\n");
			exit(1);
		}
		if (chdir(chrootdir) != 0) {
			fprintf(stderr, "aprsc: chdir(%s) failed before chroot: %s\n", chrootdir, strerror(errno));
			exit(1);
		}
		if (chroot(chrootdir)) {
			fprintf(stderr, "aprsc: chroot(%s) failed: %s\n", chrootdir, strerror(errno));
			exit(1);
		}
		if (chdir("/") != 0) { /* maybe redundant after the first chdir() */
			fprintf(stderr, "aprsc: chdir(/) failed after chroot: %s\n", strerror(errno));
			exit(1);
		}
	}
	
	/* set effective UID to non-root before opening files */
	if (setuid_s && !liveupgrade_startup)
		set_euid();
	
	/* open syslog, write an initial log message and read configuration */
	open_log(logname, 0);
	if (!quit_after_config)
		hlog(LOG_NOTICE, "Starting up version %s, instance id %s %s...",
			version_build, instance_id, (liveupgrade_startup) ? "- LIVE UPGRADE " : "");
	
	int orig_log_dest = log_dest;
	log_dest |= L_STDERR;
	
	if (read_config()) {
		hlog(LOG_CRIT, "Initial configuration failed.");
		exit(1);
	}
	
	if (quit_after_config)
		exit(0);
	
	/* adjust file limits as requested, not after every reconfigure
	 * but only at startup - we won't have root privileges available
	 * later.
	 */
	if (setuid_s)
		set_euid_0();
		
	if (new_fileno_limit > 0 && new_fileno_limit != fileno_limit && !liveupgrade_startup) {
		/* Adjust process global fileno limit */
		struct rlimit rlim;
		if (getrlimit(RLIMIT_NOFILE, &rlim) < 0)
			hlog(LOG_WARNING, "Configuration: getrlimit(RLIMIT_NOFILE) failed: %s", strerror(errno));
		rlim.rlim_cur = rlim.rlim_max = new_fileno_limit;
		if (setrlimit(RLIMIT_NOFILE, &rlim) < 0)
			hlog(LOG_WARNING, "Configuration: setrlimit(RLIMIT_NOFILE) failed: %s", strerror(errno));
		if (getrlimit(RLIMIT_NOFILE, &rlim) == 0) {
			fileno_limit = rlim.rlim_cur;
			if (fileno_limit < new_fileno_limit)
				hlog(LOG_WARNING, "Configuration could not raise FileLimit%s, it is now %d", (getuid() != 0) ? " (not running as root)" : "", fileno_limit);
		}
	}
	
	/* if setuid is needed, do so */
	if (setuid_s) {
		set_uid();
		//check_caps("after set_uid");
		if (set_final_capabilities() >= 0)
			have_low_ports = 1;
		check_caps("after set_final_capabilities");
	}
	
	/* check that we're not root - it would be insecure and really not required */
	check_uid();
	
	/* if we're not logging on stderr, we close the stderr FD after we have read configuration
	 * and opened the log file or syslog - initial config errors should go to stderr.
	 */
	if (!(log_dest & L_STDERR)) {
		close(2);
		if (dup(0) == -1) /* stderr */
			hlog(LOG_ERR, "dup(0) failed for stderr: %s", strerror(errno));
	}
	
	/* Write pid file, now that we have our final pid... might fail, which is critical.
	 * writepid locks the pid file and leaves the file descriptor open, so that
	 * reopening and re-locking the file will fail, protecting us from multiple
	 * processes running accidentally.
	 */
	if (!writepid(pidfile))
		exit(1);
	
	log_dest = orig_log_dest;
	
	/* log these only to the final log, after stderr is closed, so that
	 * a normal, successful startup does not print out informative stuff
	 * on the console
	 */
	if (have_low_ports)
		hlog(LOG_INFO, "POSIX capabilities available: can bind low ports"); 
	
	hlog(LOG_INFO, "After configuration FileLimit is %d, MaxClients is %d, xpoll using %s",
		fileno_limit, maxclients, xpoll_implementation);
	
	/* validate maxclients vs fileno_limit, now when it's determined */
	if (fileno_limit < maxclients + 50) {
		hlog(LOG_ERR, "FileLimit is smaller than MaxClients + 50: Server may run out of file descriptors and break badly");
	}
	
	/* catch signals */
	signal(SIGINT, (void *)sighandler);
	signal(SIGTERM, (void *)sighandler);
	signal(SIGQUIT, (void *)sighandler);
	signal(SIGHUP, (void *)sighandler);
	signal(SIGUSR1, (void *)sighandler);
	signal(SIGUSR2, (void *)sighandler);
	signal(SIGPIPE, SIG_IGN);
	signal(SIGURG, SIG_IGN);
	
	/* Early inits in single-thread mode */
	keyhash_init();
	filter_init();
	pbuf_init();
	dupecheck_init();
	historydb_init();
	client_heard_init();
	client_init();
	xpoll_init();
	status_init();

	/* if live upgrading, load status file and database dumps */
	if (liveupgrade_startup) {
		dbload_all();
		/* historydb must be loaded before applying filters, so do dbload_all first */
		status_read_liveupgrade();
	}
	
	pthread_attr_init(&pthr_attrs);
	/* 128 kB stack is enough for each thread,
	   default of 10 MB is way too much...*/
	pthread_attr_setstacksize(&pthr_attrs, 128*1024);

	/* start the time thread, which will update the current time */
	if (pthread_create(&time_th, &pthr_attrs, (void *)time_thread, NULL))
		perror("pthread_create failed for time_thread");

	/* start the accept thread, which will start server threads */
	if (pthread_create(&accept_th, &pthr_attrs, (void *)accept_thread, NULL))
		perror("pthread_create failed for accept_thread");

	/* start the HTTP thread, which runs libevent's HTTP server */
	if (pthread_create(&http_th, &pthr_attrs, (void *)http_thread, NULL))
		perror("pthread_create failed for http_thread");

	/* act as statistics and housekeeping thread from now on */
	while (!shutting_down) {
		if (poll(NULL, 0, 300) == -1 && errno != EINTR)
			hlog(LOG_WARNING, "main: poll sleep failed: %s", strerror(errno));
		
		if (want_dbdump) {
			dbdump_all();
			want_dbdump = 0;
		}
		
		if (reopen_logs) {
			reopen_logs = 0;
			close_log(1);
		}
		
		
		if (reconfiguring) {
			reconfiguring = 0;
			if (read_config()) {
				hlog(LOG_ERR, "New configuration was not successfully read.");
			} else {
				hlog(LOG_INFO, "New configuration read successfully. Applying....");
				accept_reconfiguring = 1;
				http_reconfiguring = 1;
			}
		}
		
		if (cleanup_tick < tick || cleanup_tick > tick + 80) {
			cleanup_tick = tick + 60;
			
			status_dump_file();
			historydb_cleanup();
			filter_wx_cleanup();
			filter_entrycall_cleanup();
		}
		
		if (version_tick < tick || version_tick > tick + 86500) {
			version_tick = tick + 86400;
			version_report("run");
		}
	}
	
	if (liveupgrade_fired)
		hlog(LOG_INFO, "Shutdown for LIVE UPGRADE!");
	
	hlog(LOG_DEBUG, "Dumping status to file");
	status_dump_file();
	
	hlog(LOG_INFO, "Signalling threads to shut down...");
	accept_shutting_down = (liveupgrade_fired) ? 2 : 1;
	
	if ((e = pthread_join(http_th, NULL)))
		hlog(LOG_ERR, "Could not pthread_join http_th: %s", strerror(e));
	else
		hlog(LOG_INFO, "HTTP thread has terminated.");
	
	if ((e = pthread_join(accept_th, NULL)))
		hlog(LOG_ERR, "Could not pthread_join accept_th: %s", strerror(e));
	else
		hlog(LOG_INFO, "Accept thread has terminated.");
		
	if ((e = pthread_join(time_th, NULL)))
		hlog(LOG_ERR, "Could not pthread_join time_th: %s", strerror(e));
	
	if (dbdump_at_exit) {
		dbdump_all();
	}

	if (liveupgrade_fired) {
		hlog(LOG_INFO, "Live upgrade: Dumping state to files...");
		dbdump_historydb();
		status_dump_liveupgrade();
		hlog(LOG_INFO, "Live upgrade: Dumps completed.");
		liveupgrade_exec(argc, argv);
	}
	
	free_config();
	dupecheck_atend();
	historydb_atend();
	filter_wx_atend();
	filter_entrycall_atend();
	status_atend();
	
	hlog(LOG_NOTICE, "Shut down.");
	close_log(0);
	
	return 0;
}