selftests: Add SO_DONTROUTE option to nettest.

Add --client-dontroute and --server-dontroute options to nettest. They
allow to set the SO_DONTROUTE option to the client and server sockets
respectively. This will be used by the following patches to test
the SO_DONTROUTE kernel behaviour with TCP and UDP.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/nettest.c

@@ -76,7 +76,9 @@ struct sock_args {
 		     has_grp:1,
 		     has_expected_laddr:1,
 		     has_expected_raddr:1,
-		     bind_test_only:1;
+		     bind_test_only:1,
+		     client_dontroute:1,
+		     server_dontroute:1;
 
 	unsigned short port;
 
@@ -611,6 +613,18 @@ static int set_dsfield(int sd, int version, int dsfield)
 	return 0;
 }
 
+static int set_dontroute(int sd)
+{
+	unsigned int one = 1;
+
+	if (setsockopt(sd, SOL_SOCKET, SO_DONTROUTE, &one, sizeof(one)) < 0) {
+		log_err_errno("setsockopt(SO_DONTROUTE)");
+		return -1;
+	}
+
+	return 0;
+}
+
 static int str_to_uint(const char *str, int min, int max, unsigned int *value)
 {
 	int number;
@@ -1351,6 +1365,14 @@ static int msock_init(struct sock_args *args, int server)
 	if (set_dsfield(sd, AF_INET, args->dsfield) != 0)
 		goto out_err;
 
+	if (server) {
+		if (args->server_dontroute && set_dontroute(sd) != 0)
+			goto out_err;
+	} else {
+		if (args->client_dontroute && set_dontroute(sd) != 0)
+			goto out_err;
+	}
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto out_err;
 	else if (args->use_setsockopt &&
@@ -1482,6 +1504,9 @@ static int lsock_init(struct sock_args *args)
 	if (set_dsfield(sd, args->version, args->dsfield) != 0)
 		goto err;
 
+	if (args->server_dontroute && set_dontroute(sd) != 0)
+		goto err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto err;
 	else if (args->use_setsockopt &&
@@ -1698,6 +1723,9 @@ static int connectsock(void *addr, socklen_t alen, struct sock_args *args)
 	if (set_dsfield(sd, args->version, args->dsfield) != 0)
 		goto err;
 
+	if (args->client_dontroute && set_dontroute(sd) != 0)
+		goto err;
+
 	if (args->dev && bind_to_device(sd, args->dev) != 0)
 		goto err;
 	else if (args->use_setsockopt &&
@@ -1905,10 +1933,14 @@ static int ipc_parent(int cpid, int fd, struct sock_args *args)
 #define GETOPT_STR  "sr:l:c:Q:p:t:g:P:DRn:M:X:m:d:I:BN:O:SUCi6xL:0:1:2:3:Fbqf"
 #define OPT_FORCE_BIND_KEY_IFINDEX 1001
 #define OPT_NO_BIND_KEY_IFINDEX 1002
+#define OPT_CLIENT_DONTROUTE 1003
+#define OPT_SERVER_DONTROUTE 1004
 
 static struct option long_opts[] = {
 	{"force-bind-key-ifindex", 0, 0, OPT_FORCE_BIND_KEY_IFINDEX},
 	{"no-bind-key-ifindex", 0, 0, OPT_NO_BIND_KEY_IFINDEX},
+	{"client-dontroute", 0, 0, OPT_CLIENT_DONTROUTE},
+	{"server-dontroute", 0, 0, OPT_SERVER_DONTROUTE},
 	{0, 0, 0, 0}
 };
 
@@ -1954,6 +1986,12 @@ static void print_usage(char *prog)
 	"    --no-bind-key-ifindex: Force TCP_MD5SIG_FLAG_IFINDEX off\n"
 	"    --force-bind-key-ifindex: Force TCP_MD5SIG_FLAG_IFINDEX on\n"
 	"        (default: only if -I is passed)\n"
+	"    --client-dontroute: don't use gateways for client socket: send\n"
+	"                        packets only if destination is on link (see\n"
+	"                        SO_DONTROUTE in socket(7))\n"
+	"    --server-dontroute: don't use gateways for server socket: send\n"
+	"                        packets only if destination is on link (see\n"
+	"                        SO_DONTROUTE in socket(7))\n"
 	"\n"
 	"    -g grp        multicast group (e.g., 239.1.1.1)\n"
 	"    -i            interactive mode (default is echo and terminate)\n"
@@ -2076,6 +2114,12 @@ int main(int argc, char *argv[])
 		case OPT_NO_BIND_KEY_IFINDEX:
 			args.bind_key_ifindex = -1;
 			break;
+		case OPT_CLIENT_DONTROUTE:
+			args.client_dontroute = 1;
+			break;
+		case OPT_SERVER_DONTROUTE:
+			args.server_dontroute = 1;
+			break;
 		case 'X':
 			args.client_pw = optarg;
 			break;