#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <err.h>
#include <netdb.h>
#include <pthread.h>
#include <stdio.h>

/*
 * Initialize a timeval to be used to time something.
 */
static int
time_begin(struct timeval *tv) {

	return (gettimeofday(tv, NULL));
}

/*
 * End the timing of something which started with time_begin().  The
 * elapsed time is returned in the second timeval passed, which can
 * be the same as the first.
 */
static int
time_end(const struct timeval *otv, struct timeval *tv) {
	struct timeval endtv;
	int error;

	error = gettimeofday(&endtv, NULL);
	if (error != 0)
		return (error);
	tv->tv_sec = endtv.tv_sec - otv->tv_sec;
	tv->tv_usec = endtv.tv_usec - otv->tv_usec;
	if (tv->tv_usec < 0) {
		tv->tv_sec--;
		tv->tv_usec += 1000000;
	}
	return (0);
}

/*
 * Convert a timeval to... well... a double.
 */
static inline double
tvtod(const struct timeval *tv) {

	return ((double)tv->tv_sec + (double)tv->tv_usec / 1000000);
}

pthread_mutex_t netdb_mutex;

void *
lookup(void *arg) {
	const char *host = arg;
	struct hostent *h;
	char addr[64];
	struct timeval tv;

	if (pthread_mutex_lock(&netdb_mutex) != 0) {
		warn("mutex_lock");
		pthread_exit(NULL);
	}
	(void)time_begin(&tv);
	h = gethostbyname(host);
	(void)time_end(&tv, &tv);
	if (h == NULL || inet_ntop(h->h_addrtype, h->h_addr, addr,
	    sizeof(addr)) == NULL)
		strncpy(addr, "failure", sizeof(addr));
	(void)pthread_mutex_unlock(&netdb_mutex);
	printf("lookup %s: %s\t\t%.3f seconds\n", host, addr, tvtod(&tv));
	pthread_exit(NULL);
}

int
main() {
	const char *const hosts[] = {
		"freefall.freebsd.org",
		"localhost",
		"www.mozilla.org",
		"www.ruby-lang.org"
	};
	const size_t nlookups = sizeof(hosts) / sizeof(hosts[0]);
	pthread_t lookups[nlookups];
	int i;

	if (pthread_mutex_init(&netdb_mutex, NULL) != 0)
		err(1, "mutex_init");
	for (i = 0; i < nlookups; i++)
		if (pthread_create(&lookups[i], NULL, lookup,
		    (void *)hosts[i]) != 0)
			err(1, "create");
	for (i = 0; i < nlookups; i++)
		(void)pthread_join(lookups[i], NULL);
	exit(0);
}