Re: [Patch, v2, 2/2] BCC: python: add a useful tool for mptcp

[Matthieu Baerts <matttbe@kernel.org>]

Hi Gang,

On 09/04/2025 09:17, Gang Yan wrote:
> Multipath TCP (MPTCP) is an extension of the standard TCP protocol
> that allows a single transport connection to use multiple network
> interfaces or paths. MPTCP is useful for applications like bandwidth
> aggregation, failover, and more resilient connections.
> 
> Linux kernel starts to support MPTCP since v5.6, this patch provides
> a method which can easily force applications use MPTCP socket without
> modifing its code.
> 
> Signed-off-by: Gang Yan <yangang@kylinos.cn>
> ---
>  tools/mptcpify.py  | 80 ++++++++++++++++++++++++++++++++++++++++++++++
>  tools/mptcpify.txt | 22 +++++++++++++
>  2 files changed, 102 insertions(+)
>  create mode 100644 tools/mptcpify.py
>  create mode 100644 tools/mptcpify.txt
> 
> diff --git a/tools/mptcpify.py b/tools/mptcpify.py
> new file mode 100644
> index 00000000..efdbd910
> --- /dev/null
> +++ b/tools/mptcpify.py
> @@ -0,0 +1,80 @@
> +#!/usr/bin/env python
> +#
> +# mptcpify Make the applications to use MPTCP.
> +#           For Linux, uses BCC, eBPF. Embedded C.
> +#
> +# USAGE: mptcpify -t
> +#
> +# Copyright 2025 Kylin Software, Inc.
> +# Licensed under the Apache License, Version 2.0 (the "License")
> +#
> +# 05-Apr-2025   Gang Yan   Created this.
> +
> +import ctypes as ct
> +import argparse
> +import signal
> +import time
> +
> +from bcc import BPF
> +
> +#arguments
> +parser = argparse.ArgumentParser(
> +         description="mptcpify try to force applications to use MPTCP instead of TCP")
> +parser.add_argument("-t", "--targets", required=True, type=str,
> +                    help="use ',' for multi targets, eg: 'iperf3,rsync'")

If it is easy for you to have this argument optional, don't hesitate to
add this support: I think it will be useful to have this mode
"everything is forced to use MPTCP".

(...)

> +b = BPF(text=prog)
> +b.attach_fmod_ret("update_socket_protocol")
> +
> +support_apps = b.get_table("support_apps")
> +for i in args_list:
> +    app = i.encode()
> +    name = app_name()
> +    name.str = app[:TASK_COMM_LEN-1].ljust(TASK_COMM_LEN, b'\0')
> +    support_apps[name] = ct.c_uint32(1)
> +
> +print("MPTCP is been forced for ", args_list);

Detail: maybe better with "is being forced".

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.