Add a small regression test that opens a TCP socket, listens on it,

performs a non-blocking connect from another socket, and then closes
the listen socket rather than accepting.  This is intended to
exercise the close path in which connections are aborted due to a
close on the listen socket while the connection is in the listen
queue.

tools/regression/sockets/listenclose/Makefile

@@ -0,0 +1,9 @@
+#
+# $FreeBSD$
+#
+
+PROG=	listenclose
+NOMAN=	yes
+WARNS=	2
+
+.include <bsd.prog.mk>

tools/regression/sockets/listenclose/listenclose.c

@@ -0,0 +1,111 @@
+/*-
+ * Copyright (c) 2004 Robert N. M. Watson
+ * 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <netinet/in.h>
+
+#include <arpa/inet.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+/*
+ * The listenclose regression test is designed to catch kernel bugs that may
+ * trigger as a result of performing a close on a listen() socket with as-yet
+ * unaccepted connections in its queues.  This results in the connections
+ * being aborted, which is a not-often-followed code path.  To do this, we
+ * create a local TCP socket, build a non-blocking connection to it, and then
+ * close the accept socket.  The connection must be non-blocking or the
+ * program will block and as such connect() will not return as accept() is
+ * never called.
+ */
+
+int
+main(int argc, char *argv[])
+{
+	int listen_sock, connect_sock;
+	struct sockaddr_in sin;
+	socklen_t len;
+	u_short port;
+	int arg;
+
+	listen_sock = socket(PF_INET, SOCK_STREAM, 0);
+	if (listen_sock == -1)
+		errx(-1,
+		    "socket(PF_INET, SOCK_STREAM, 0) for listen socket: %s",
+		    strerror(errno));
+
+
+	bzero(&sin, sizeof(sin));
+	sin.sin_len = sizeof(sin);
+	sin.sin_family = AF_INET;
+	sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+	sin.sin_port = 0;
+
+	if (bind(listen_sock, (struct sockaddr *)&sin, sizeof(sin)) < 0)
+		errx(-1, "bind(%s, %d) for listen socket: %s",
+		    inet_ntoa(sin.sin_addr), 0, strerror(errno));
+
+	len = sizeof(sin);
+	if (getsockname(listen_sock, (struct sockaddr *)&sin, &len) < 0)
+		errx(-1, "getsockname() for listen socket: %s",
+		    strerror(errno));
+	port = sin.sin_port;
+
+	if (listen(listen_sock, -1) < 0)
+		errx(-1, "listen() for listen socket: %s", strerror(errno));
+
+	connect_sock = socket(PF_INET, SOCK_STREAM, 0);
+	if (connect_sock == -1)
+		errx(-1, "socket(PF_INET, SOCK_STREAM, 0) for connect "
+		    "socket: %s", strerror(errno));
+
+	arg = O_NONBLOCK;
+	if (fcntl(connect_sock, F_SETFL, &arg) < 0)
+		errx(-1, "socket(PF_INET, SOCK_STREAM, 0) for connect socket"
+		    ": %s", strerror(errno));
+
+	bzero(&sin, sizeof(sin));
+	sin.sin_len = sizeof(sin);
+	sin.sin_family = AF_INET;
+	sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+	sin.sin_port = port;
+
+	if (connect(connect_sock, (struct sockaddr *)&sin, sizeof(sin)) < 0)
+		errx(-1, "connect() for connect socket: %s", strerror(errno));
+
+	close(listen_sock);
+
+	return (0);
+}