netdev - Re: [PATCH bpf-next] tools: bpftool: make it easier to feed hex bytes to bpftool

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Message-ID: <922fbe1c-1da4-4c9d-f1d4-18f3546ff5b8@iogearbox.net>
Date:   Wed, 18 Apr 2018 14:51:06 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        alexei.starovoitov@...il.com
Cc:     oss-drivers@...ronome.com, netdev@...r.kernel.org,
        Quentin Monnet <quentin.monnet@...ronome.com>
Subject: Re: [PATCH bpf-next] tools: bpftool: make it easier to feed hex bytes
 to bpftool

On 04/18/2018 04:46 AM, Jakub Kicinski wrote:
> From: Quentin Monnet <quentin.monnet@...ronome.com>
> 
> bpftool uses hexadecimal values when it dumps map contents:
> 
>     # bpftool map dump id 1337
>     key: ff 13 37 ff  value: a1 b2 c3 d4 ff ff ff ff
>     Found 1 element
> 
> In order to lookup or update values with bpftool, the natural reflex is
> then to copy and paste the values to the command line, and to try to run
> something like:
> 
>     # bpftool map update id 1337 key ff 13 37 ff \
>             value 00 00 00 00 00 00 1a 2b
>     Error: error parsing byte: ff
> 
> bpftool complains, because it uses strtoul() with a 0 base to parse the
> bytes, and that without a "0x" prefix, the bytes are considered as
> decimal values (or even octal if they start with "0").
> 
> To feed hexadecimal values instead, one needs to add "0x" prefixes
> everywhere necessary:
> 
>     # bpftool map update id 1337 key 0xff 0x13 0x37 0xff \
>             value 0 0 0 0 0 0 0x1a 0x2b
> 
> To make it easier to use hexadecimal values, add an optional "hex"
> keyword to put after "key" or "value" to tell bpftool to consider the
> digits as hexadecimal. We can now do:
> 
>     # bpftool map update id 1337 key hex ff 13 37 ff \
>             value hex 0 0 0 0 0 0 1a 2b
> 
> Without the "hex" keyword, the bytes are still parsed according to
> normal integer notation (decimal if no prefix, or hexadecimal or octal
> if "0x" or "0" prefix is used, respectively).
> 
> The patch also add related documentation and bash completion for the
> "hex" keyword.
> 
> Suggested-by: Daniel Borkmann <daniel@...earbox.net>
> Suggested-by: David Beckett <david.beckett@...ronome.com>
> Signed-off-by: Quentin Monnet <quentin.monnet@...ronome.com>
> Acked-by: Jakub Kicinski <jakub.kicinski@...ronome.com>

Applied to bpf-next, thanks Quentin!