/*
 * Let a socket fill up until input is received, then drain the buffer.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <err.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static void
usage(void)
{

	fprintf(stderr, "tcpslow <host> <port>\n");
	exit(1);
}

static int
tcp(char *host, char *port)
{
	struct addrinfo hints, *ai, *list;
	char hname[NI_MAXHOST], service[NI_MAXSERV];
	int error, optval, s;

	/* Lookup the host/port address. */
	bzero(&hints, sizeof(hints));
	hints.ai_family = PF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	error = getaddrinfo(host, port, &hints, &list);
	if (error)
		errx(1, "getaddrinfo: %s", gai_strerror(error));

	/*
	 * Walk the list trying to connect to each address.  Return
	 * the first socket that connects.
	 */
	for (ai = list; ai != NULL; ai = ai->ai_next) {
		getnameinfo(ai->ai_addr, ai->ai_addrlen, hname, sizeof(hname),
		    service, sizeof(service), NI_NUMERICHOST | NI_NUMERICSERV);
		s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
		if (s < 0) {
			warn("socket(%s:%s)", hname, service);
			continue;
		}

		if (connect(s, ai->ai_addr, ai->ai_addrlen) < 0) {
			warn("connect(%s:%s)", hname, service);
			close(s);
			continue;
		}

		break;
	}
	freeaddrinfo(list);

	/* Fail if we never connected. */
	if (ai == NULL)
		errx(1, "failed to connect");

	/* Set the socket to non-blocking. */
	optval = fcntl(s, F_GETFL);
	if (optval == -1)
		err(1, "fcntl(F_GETFL)");
	optval |= O_NONBLOCK;
	if (fcntl(s, F_SETFL, optval) == -1)
		err(1, "fcntl(F_SETFL)");
	return (s);
}

int
main(int ac, char **av)
{
	char buffer[1024];
	int i, idle, s;
	ssize_t nread;

	if (ac != 3)
		usage();

	s = tcp(av[1], av[2]);

	/* Drain socket buffer with periodic pauses. */
	idle = 0;
	for (i = 0;; i++) {
		nread = read(s, buffer, sizeof(buffer));
		if (nread == 0) {
			if (!idle)
				printf("idle...\n");
			idle = 1;
		}
		if (idle || i % 64 == 0)
			usleep(15 * 1000 * 1000);
	}
	close(s);
	return (0);
}