Add a test for the listen queue using two test programs,

listen, and connect.  The listen program is a simple server that
accepts and closes sockets, until a fixed limit, then sets the listen
queue to 0 and counts how many remaining connections it processes.

The connect program repeatedly opens connections and closes them
serving as the driver for the listen program.

Sponsored by:	Limelight Networks

tools/test/net/Makefile

@@ -0,0 +1,9 @@
+# $FreeBSD$ 
+
+PROGS=	listen connect
+MAN=
+WARNS?=	6
+
+test:	${PROGS}
+
+.include <bsd.prog.mk>

tools/test/net/connect.c

@@ -0,0 +1,86 @@
+/*-
+ * Copyright (c) 2015 George V. Neville-Neil
+ * 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 <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+
+#define PORT 6969 /* Default port */
+#define RECV_LIMIT 64 /* When do we move listen to 0? */
+
+void usage(void);
+
+void usage()
+{
+	err(EX_USAGE, "connect [-p port]\n");
+}
+
+int main(int argc, char **argv)
+{
+
+	int ch, cli_sock, count = 0;
+	int port = PORT;
+	struct sockaddr_in remoteaddr;
+
+	while ((ch = getopt(argc, argv, "p:")) != -1) {
+		switch (ch) {
+		case 'p':
+			port = atoi(optarg);
+			break;
+		case 'h':
+		default:
+			usage();
+		}
+	}
+
+	bzero(&remoteaddr, sizeof(remoteaddr));
+	remoteaddr.sin_len = sizeof(remoteaddr);
+	remoteaddr.sin_family = AF_INET;
+	remoteaddr.sin_port = htons(port);
+	remoteaddr.sin_addr.s_addr = INADDR_ANY;
+
+	cli_sock = socket(AF_INET, SOCK_STREAM, 0);
+
+	while ((cli_sock = connect(cli_sock, (struct sockaddr *)&remoteaddr,
+				   sizeof(remoteaddr))) >= 0) {
+		count++;
+		close(cli_sock);
+		cli_sock = socket(AF_INET, SOCK_STREAM, 0);
+	}
+
+	printf("Exiting at %d with errno %d\n", count, errno);
+
+}

tools/test/net/listen.c

@@ -0,0 +1,106 @@
+/*-
+ * Copyright (c) 2015 George V. Neville-Neil
+ * 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 <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+
+#define PORT 6969 /* Default port */
+#define LISTEN 5  /* Default backlog */
+#define RECV_LIMIT 64 /* When do we move listen to 0? */
+
+void usage(void);
+
+void usage()
+{
+	err(EX_USAGE, "listen [-p port] [-l limit]\n");
+}
+
+int main(int argc, char **argv)
+{
+
+	int ch, srv_sock, cli_sock, recvd = 0;
+	int port = PORT;
+	int limit = LISTEN;
+	struct sockaddr_in localaddr;
+
+	while ((ch = getopt(argc, argv, "p:l:")) != -1) {
+		switch (ch) {
+		case 'p':
+			port = atoi(optarg);
+			break;
+		case 'l':
+			limit = atoi(optarg);
+                     break;
+		case 'h':
+		default:
+			usage();
+		}
+	}
+
+	bzero(&localaddr, sizeof(localaddr));
+	localaddr.sin_len = sizeof(localaddr);
+	localaddr.sin_family = AF_INET;
+	localaddr.sin_port = htons(port);
+	localaddr.sin_addr.s_addr = INADDR_ANY;
+
+	srv_sock = socket(AF_INET, SOCK_STREAM, 0);
+
+	if (bind(srv_sock, (struct sockaddr *)&localaddr,
+		 sizeof(struct sockaddr_in)) < 0)
+		err(EX_OSERR, "Could not bind to INADDR_ANY:%d", port);
+	
+	if (listen(srv_sock, limit) < 0)
+		err(EX_OSERR, "Failed to listen with depth of %d\n", limit);
+	
+	while (((cli_sock = accept(srv_sock, NULL, NULL)) >= 0)
+	       && (recvd < RECV_LIMIT)) {
+		close(cli_sock);
+		recvd++;
+	}
+
+	listen(srv_sock, 0);
+
+	while (((cli_sock = accept(srv_sock, NULL, NULL)) >= 0)
+	    && (recvd <= (RECV_LIMIT + limit + 1))) {
+		close(cli_sock);
+		recvd++;
+	}
+
+	if (accept(srv_sock, NULL, NULL) >= 0)
+		printf ("Late connection at %d\n", recvd);
+	else
+		printf("recvd %d\n", recvd);
+}