Subject: Re: [PATCH bpf-next v9 4/4] selftests/bpf: Add mptcpify test

From: Yonghong Song <[email-masked]>
Date: Thu, 3 Aug 2023 18:23:57 -0700

On 8/3/23 6:41 AM, Geliang Tang wrote:
> Implement a new test program mptcpify: if the family is AF_INET or
> AF_INET6, the type is SOCK_STREAM, and the protocol ID is 0 or
> IPPROTO_TCP, set it to IPPROTO_MPTCP. It will be hooked in
> update_socket_protocol().
> 
> Extend the MPTCP test base, add a selftest test_mptcpify() for the
> mptcpify case. Open and load the mptcpify test prog to mptcpify the
> TCP sockets dynamically, then use start_server() and connect_to_fd()
> to create a TCP socket, but actually what's created is an MPTCP
> socket, which can be verified through the outputs of 'ss' and 'nstat'
> commands.
> 
> Reviewed-by: Matthieu Baerts <[email-masked]>
> Signed-off-by: Geliang Tang <[email-masked]>
> ---
>   .../testing/selftests/bpf/prog_tests/mptcp.c  | 94 +++++++++++++++++++
>   tools/testing/selftests/bpf/progs/mptcpify.c  | 25 +++++
>   2 files changed, 119 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/progs/mptcpify.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
> index 4407bd5c9e9a..caab3aa6a162 100644
> --- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
> +++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
> @@ -6,6 +6,7 @@
>   #include "cgroup_helpers.h"
>   #include "network_helpers.h"
>   #include "mptcp_sock.skel.h"
> +#include "mptcpify.skel.h"
>   
>   char NS_TEST[32];
>   
> @@ -195,8 +196,101 @@ static void test_base(void)
>   	close(cgroup_fd);
>   }
>   
> +static void send_byte(int fd)
> +{
> +	char b = 0x55;
> +
> +	ASSERT_EQ(write(fd, &b, sizeof(b)), 1, "send single byte");
> +}
> +
> +static int verify_mptcpify(void)
> +{
> +	char cmd[256];
> +	int err = 0;
> +
> +	snprintf(cmd, sizeof(cmd),
> +		 "ip netns exec %s ss -tOni | grep -q '%s'",
> +		 NS_TEST, "tcp-ulp-mptcp");

Could you show what is the expected output from the above command line
   ip netns exec %s ss -tOni
?
This way, users can easily reason about the ss states based on tests.

> +	if (!ASSERT_OK(system(cmd), "No tcp-ulp-mptcp found!"))
> +		err++;
> +
> +	snprintf(cmd, sizeof(cmd),
> +		 "ip netns exec %s nstat -asz %s | awk '%s' | grep -q '%s'",
> +		 NS_TEST, "MPTcpExtMPCapableSYNACKRX",
> +		 "NR==1 {next} {print $2}", "1");

The same thing here. Could you show the expected output with
    ip netns exec %s nstat -asz %s
?

> +	if (!ASSERT_OK(system(cmd), "No MPTcpExtMPCapableSYNACKRX found!"))
> +		err++;
> +
> +	return err;
> +}
> +
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