kqueue

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/event.h>
#include <sys/time.h>
#include <errno.h>

void die(const char*);

int main(int argc, char *argv[])
{
	int sockfd, nev, kq;

	struct addrinfo hints, *res, *res0;

	struct kevent change[2], event[2];

	ssize_t nbytes;

	char buf[BUFSIZ];

	const char *cause = NULL;

	if (3 != argc)
	{
		fprintf(stderr, "Usage: %s address port\n", argv[0]);
		exit(EXIT_FAILURE);
	}

	(void)memset(&hints, '\0', sizeof(struct addrinfo));

	hints.ai_family = AF_INET;
	hints.ai_socktype = SOCK_STREAM;

	if (-1 == getaddrinfo(argv[1], argv[2], &hints, &res0))
		die("getaddrinfo");

	sockfd = -1;

	for (res = res0; res; res = res->ai_next)
	{
		if (-1 == (sockfd = socket(res->ai_family, res->ai_socktype,
		 res->ai_protocol)))
		{
			cause = "socket";
			continue;
		}

		if (-1 == connect(sockfd, res->ai_addr, res->ai_addrlen))
		{
			cause = "connect()";
			close(sockfd);
			continue;
		}

		break;

	}

	if (-1 == sockfd)
		die(cause);

	if (-1 == fcntl(sockfd, F_SETFL, O_NONBLOCK))
		die("fcntl1()");

	if (-1 == fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK))
		die("fcntl()");

	if (-1 == (kq = kqueue()))
		die("kqueue()");

	EV_SET(&change[0], STDIN_FILENO, EVFILT_READ, EV_ADD | EV_ENABLE,
	 0, 0, 0);
	EV_SET(&change[1], sockfd, EVFILT_READ, EV_ADD | EV_ENABLE,
	 0, 0, 0);

	for (;;)
	{
		if (-1 == (nev = kevent(kq, change, 2, event, 2, NULL)))
			die("kevent()");

		for (int i = 0; i < nev; i++)
		{
			if (event[i].ident == STDIN_FILENO)
			{
				fgets(buf, sizeof(buf), stdin);

				nbytes = send(sockfd, buf, strlen(buf), 0);

				if (-1 == nbytes)
					if (EWOULDBLOCK != errno)
						die("send()");

			}
			else
			{
				nbytes = recv(sockfd, buf, sizeof(buf), 0);

				if (-1 == nbytes)
					if (EWOULDBLOCK != errno)
						die("recv()");

				buf[nbytes] = '\0';

				write(STDOUT_FILENO, buf, strlen(buf));
			}

		}

	}

	return 0;
}

void die(const char *str)
{
	perror(str);
	exit(EXIT_FAILURE);
}