/*-
 * Copyright (c) 2010 Mikolaj Golub
 * All rights reserved.
 *
 * 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.
 */

/*
 * This regression test attempts to trigger a race that occurs when both
 * endpoints of a connected UNIX domain socket are closed at once.  The two
 * close paths may run concurrently leading to a call to sodisconnect() on an
 * already-closed socket in kernel.  Before it was fixed, this might lead to
 * ENOTCONN being returned improperly from close().
 *
 * This race is fairly timing-dependent, so it effectively requires SMP, and
 * may not even trigger then.
 */

#include <sys/types.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <strings.h>
#include <string.h>
#include <unistd.h>
#include <err.h>

static char socket_path[] = "tmp.XXXXXXXX";

#define USLEEP  100
#define LOOPS   100000

int
main(void)
{
        struct sockaddr_un servaddr;
        int listenfd, connfd, pid;
        u_int counter, ncpus;
        size_t len;

        len = sizeof(ncpus);
        if (sysctlbyname("kern.smp.cpus", &ncpus, &len, NULL, 0) < 0)
                err(1, "kern.smp.cpus");
        if (len != sizeof(ncpus))
                errx(1, "kern.smp.cpus: invalid length");
        if (ncpus < 2)
                warnx("SMP not present, test may be unable to trigger race");

        if (mkstemp(socket_path) == -1)
                err(1, "mkstemp failed");
        unlink(socket_path);

        /*
         * Create a UNIX domain socket that the child will repeatedly
         * accept() from, and that the parent will repeatedly connect() to.
         */
        if ((listenfd = socket(AF_LOCAL, SOCK_STREAM, 0)) < 0)
                err(1, "parent: socket error");
        (void)unlink(socket_path);
        bzero(&servaddr, sizeof(servaddr));
        servaddr.sun_family = AF_LOCAL;
        strcpy(servaddr.sun_path, socket_path);
        if (bind(listenfd, (struct sockaddr *) &servaddr,
            sizeof(servaddr)) < 0)
                err(1, "parent: bind error");
        if (listen(listenfd, 1024) < 0)
                err(1, "parent: listen error");

        pid = fork();
        if (pid == -1)
                err(1, "fork()");
        if (pid != 0) {
                /*
                 * In the parent, repeatedly connect and disconnect from the
                 * socket, attempting to induce the race.
                 */
                close(listenfd);
                sleep(1);
                bzero(&servaddr, sizeof(servaddr));
                servaddr.sun_family = AF_LOCAL;
                strcpy(servaddr.sun_path, socket_path);
                for (counter = 0; counter < LOOPS; counter++) {
                        if ((connfd = socket(AF_LOCAL, SOCK_STREAM, 0)) < 0) {
                                (void)kill(pid, SIGTERM);
                                err(1, "parent: socket error");
                        }
                        if (connect(connfd, (struct sockaddr *)&servaddr,
                            sizeof(servaddr)) < 0) {
                                (void)kill(pid, SIGTERM);
                                err(1, "parent: connect error");
                        }
                        if (close(connfd) < 0) {
                                (void)kill(pid, SIGTERM);
                                err(1, "parent: close error");
                        }
                        usleep(USLEEP);
                }
                (void)kill(pid, SIGTERM);
        } else {
                /*
                 * In the child, loop accepting and closing.  We may pick up
                 * the race here so report errors from close().
                 */
                for ( ; ; ) {
                        if ((connfd = accept(listenfd,
                            (struct sockaddr *)NULL, NULL)) < 0)
                                err(1, "child: accept error");
                        if (close(connfd) < 0)
                                err(1, "child: close error");
                }
        }
        printf("OK\n");
        exit(0);
}