selftests/bpf: Add mptcp subflow subtest

This patch adds a subtest named test_subflow to load and verify the newly
added mptcp subflow example in test_mptcp. Add a helper endpoint_init()
to add a new subflow endpoint. Add another helper has_in_subflow() to
verify the fwmark and congestion values set by mptcp_subflow prog using
setsockopts.

Closes: multipath-tcp#76
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>

tools/testing/selftests/bpf/prog_tests/mptcp.c

@@ -10,6 +10,7 @@
 #include "network_helpers.h"
 #include "mptcp_sock.skel.h"
 #include "mptcpify.skel.h"
+#include "mptcp_subflow.skel.h"
 #include "mptcp_bpf_first.skel.h"
 #include "mptcp_bpf_bkup.skel.h"
 #include "mptcp_bpf_rr.skel.h"
@@ -328,6 +329,93 @@ static void test_mptcpify(void)
 	close(cgroup_fd);
 }
 
+#define ADDR_1	"10.0.1.1"
+#define ADDR_2	"10.0.1.2"
+#define PORT_1	10001
+
+static int endpoint_init(char *flags)
+{
+	SYS(fail, "ip -net %s link add veth1 type veth peer name veth2", NS_TEST);
+	SYS(fail, "ip -net %s addr add %s/24 dev veth1", NS_TEST, ADDR_1);
+	SYS(fail, "ip -net %s link set dev veth1 up", NS_TEST);
+	SYS(fail, "ip -net %s addr add %s/24 dev veth2", NS_TEST, ADDR_2);
+	SYS(fail, "ip -net %s link set dev veth2 up", NS_TEST);
+	SYS(fail, "ip -net %s mptcp endpoint add %s %s", NS_TEST, ADDR_2, flags);
+
+	return 0;
+fail:
+	return -1;
+}
+
+static int has_in_subflow(char *src, char *str)
+{
+	char cmd[128];
+
+	snprintf(cmd, sizeof(cmd),
+		 "ip netns exec %s ss -Menita src %s dst %s dport %d | grep -q '%s'",
+		 NS_TEST, src, ADDR_1, PORT_1, str);
+	return system(cmd);
+}
+
+static void run_test_subflow(int cgroup_fd)
+{
+	int server_fd, client_fd, prog_fd, err;
+	struct mptcp_subflow *skel;
+
+	skel = mptcp_subflow__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_load"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.mptcp_subflow);
+	err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SOCK_OPS, 0);
+	if (!ASSERT_OK(err, "bpf_prog_attach"))
+		goto cleanup;
+
+	server_fd = start_mptcp_server(AF_INET, ADDR_1, PORT_1, 0);
+	if (!ASSERT_GE(server_fd, 0, "start_mptcp_server"))
+		goto cleanup;
+
+	client_fd = connect_to_fd(server_fd, 0);
+	if (!ASSERT_GE(client_fd, 0, "connect to fd"))
+		goto close_server;
+
+	send_byte(client_fd);
+
+	ASSERT_OK(has_in_subflow(ADDR_1, "fwmark:0x1"), "has_in_subflow fwmark:0x1");
+	ASSERT_OK(has_in_subflow(ADDR_2, "fwmark:0x2"), "has_in_subflow fwmark:0x2");
+	ASSERT_OK(has_in_subflow(ADDR_1, "reno"), "has_in_subflow reno");
+	ASSERT_OK(has_in_subflow(ADDR_2, "cubic"), "has_in_subflow cubic");
+
+	close(client_fd);
+close_server:
+	close(server_fd);
+cleanup:
+	mptcp_subflow__destroy(skel);
+}
+
+void test_subflow(void)
+{
+	struct nstoken *nstoken = NULL;
+	int cgroup_fd;
+
+	cgroup_fd = test__join_cgroup("/mptcp_subflow");
+	if (!ASSERT_GE(cgroup_fd, 0, "test__join_cgroup"))
+		return;
+
+	nstoken = create_netns();
+	if (!ASSERT_OK_PTR(nstoken, "create_netns"))
+		goto fail;
+
+	if (!ASSERT_OK(endpoint_init("subflow"), "endpoint_init"))
+		goto fail;
+
+	run_test_subflow(cgroup_fd);
+
+fail:
+	cleanup_netns(nstoken);
+	close(cgroup_fd);
+}
+
 static const unsigned int total_bytes = 10 * 1024 * 1024;
 static int stop, duration;
 
@@ -657,6 +745,8 @@ void test_mptcp(void)
 		test_base();
 	if (test__start_subtest("mptcpify"))
 		test_mptcpify();
+	if (test__start_subtest("subflow"))
+		test_subflow();
 	if (test__start_subtest("default"))
 		test_default();
 	if (test__start_subtest("first"))