tcpdrop.c

/*-
 * Copyright (c) 2006 Robert N. M. Watson
 * Copyright (c) 2011 Juniper Networks, Inc.
 * All rights reserved.
 *
 * Portions of this software were developed by Robert N. M. Watson under
 * contract to Juniper Networks, Inc.
 *
 * 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 AUTHOR 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 AUTHOR 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.
 */

/*
 * TCP regression test for the tcpdrop sysctl; build a loopback TCP
 * connection, drop it, and make sure both endpoints return that the
 * connection has been reset.
 */

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

#include <netinet/in.h>

#include <err.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static int
tcp_drop(struct sockaddr_in *sin_local, struct sockaddr_in *sin_remote)
{
	struct sockaddr_storage addrs[2];

	/*
	 * Sysctl accepts an array of two sockaddr's, the first being the
	 * 'foreign' sockaddr, the second being the 'local' sockaddr.
	 */

	bcopy(sin_remote, &addrs[0], sizeof(*sin_remote));
	bcopy(sin_local, &addrs[1], sizeof(*sin_local));

	return (sysctlbyname("net.inet.tcp.drop", NULL, 0, addrs,
	    sizeof(addrs)));
}

static void
tcp_server(pid_t partner, int listen_fd)
{
	int error, accept_fd;
	ssize_t len;
	char ch;

	accept_fd = accept(listen_fd, NULL, NULL);
	if (accept_fd < 0) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "tcp_server: accept");
	}

	/*
	 * Send one byte, make sure that worked, wait for the drop, and try
	 * sending another.  By sending small amounts, we avoid blocking
	 * waiting on the remote buffer to be drained.
	 */
	ch = 'A';
	len = send(accept_fd, &ch, sizeof(ch), MSG_NOSIGNAL);
	if (len < 0) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "tcp_server: send (1)");
	}
	if (len != sizeof(ch)) {
		(void)kill(partner, SIGTERM);
		errx(-1, "tcp_server: send (1) len");
	}

	sleep (10);

	ch = 'A';
	len = send(accept_fd, &ch, sizeof(ch), MSG_NOSIGNAL);
	if (len >= 0) {
		(void)kill(partner, SIGTERM);
		errx(-1, "tcp_server: send (2): success");
	} else if (errno != EPIPE) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "tcp_server: send (2)");
	}

	close(accept_fd);
	close(listen_fd);
}

static void
tcp_client(pid_t partner, u_short port)
{
	struct sockaddr_in sin, sin_local;
	int error, sock;
	socklen_t slen;
	ssize_t len;
	char ch;

	sleep(1);

	sock = socket(PF_INET, SOCK_STREAM, 0);
	if (sock < 0) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "socket");
	}

	bzero(&sin, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_len = sizeof(sin);
	sin.sin_addr.s_addr = ntohl(INADDR_LOOPBACK);
	sin.sin_port = port;

	if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "connect");
	}

	slen = sizeof(sin_local);
	if (getsockname(sock, (struct sockaddr *)&sin_local, &slen) < 0) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "getsockname");
	}

	/*
	 * Send one byte, make sure that worked, wait for the drop, and try
	 * sending another.  By sending small amounts, we avoid blocking
	 * waiting on the remote buffer to be drained.
	 */
	ch = 'A';
	len = send(sock, &ch, sizeof(ch), MSG_NOSIGNAL);
	if (len < 0) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "tcp_client: send (1)");
	}
	if (len != sizeof(ch)) {
		(void)kill(partner, SIGTERM);
		errx(-1, "tcp_client: send (1) len");
	}

	sleep(5);
	if (tcp_drop(&sin_local, &sin) < 0) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "tcp_client: tcp_drop");
	}
	sleep(5);

	ch = 'A';
	len = send(sock, &ch, sizeof(ch), MSG_NOSIGNAL);
	if (len >= 0) {
		(void)kill(partner, SIGTERM);
		errx(-1, "tcp_client: send (2): success");
	} else if (errno != EPIPE) {
		error = errno;
		(void)kill(partner, SIGTERM);
		errno = error;
		err(-1, "tcp_client: send (2)");
	}
	close(sock);
}

int
main(int argc, char *argv[])
{
	pid_t child_pid, parent_pid;
	struct sockaddr_in sin;
	int listen_fd;
	u_short port;
	socklen_t len;

	listen_fd = socket(PF_INET, SOCK_STREAM, 0);
	if (listen_fd < 0)
		err(-1, "socket");

	/*
	 * We use the loopback, but let the kernel select a port for the
	 * server socket.
	 */
	bzero(&sin, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_len = sizeof(sin);
	sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);

	if (bind(listen_fd, (struct sockaddr *)&sin, sizeof(sin)) < 0)
		err(-1, "bind");

	if (listen(listen_fd, -1) < 0)
		err(-1, "listen");

	/*
	 * Query the port so that the client can use it.
	 */
	bzero(&sin, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_len = sizeof(sin);
	len = sizeof(sin);
	if (getsockname(listen_fd, (struct sockaddr *)&sin, &len) < 0)
		err(-1, "getsockname");
	port = sin.sin_port;
	printf("Using port %d\n", ntohs(port));

	if (signal(SIGCHLD, SIG_IGN) == SIG_ERR)
		err(-1, "signal");

	parent_pid = getpid();
	child_pid = fork();
	if (child_pid < 0)
		err(-1, "fork");
	if (child_pid == 0) {
		child_pid = getpid();
		tcp_server(parent_pid, listen_fd);
	} else
		tcp_client(child_pid, port);

	return (0);
}