Re: [libnftnl PATCH 0/9] Fix for debug output on Big Endian

[Phil Sutter <phil@nwl.cc>]

On Thu, Oct 23, 2025 at 06:05:38PM +0200, Phil Sutter wrote:
> This series aims at providing identical netlink debug output in nftables
> on Big and Little Endian systems. Particularly problematic are all data
> regs in host byte order, worsened by the potential for byte order swaps
> within a single data reg (concatenated set elements).
> 
> A bonus task is cropping data reg values to their actual size.
> Previously, every four-byte register containing data was printed which
> further reduces data expressiveness.
> 
> This series introduces data attribute setters for expressions and set
> elements which accept a byteorder value (plus an array of component
> sizes in the latter case) and changes the data reg printer to:
> 
> - Print only nftnl_data_reg::len bytes at max
> - Print data byte-by-byte, not four byte chunks as u32 values
>   interpreted in host byte order
> - Print data in reverse if in host byte order on Little Endian
> 
> If nftnl_data_reg::sizes array has non-zero fields, data is assumed to
> be concatenated and bits in nftnl_data_reg::byteorder signal host byte
> order in components. Each component is then printed as per the above
> rules and separated by a dot (".").
> 
> Patches 3-8 implement the above. Since debug output changes
> significantly, use the occasion to:
> - Print a colon (":") and flags value only if relevant (patch 1)
> - Fix for missing object name in objmap elements (patch 1)
> - Avoid ambiguity between data and flags value by prefixing with 'flags'
>   (patch 1)
> - Avoid trailing whitespace or space before tab (patch 2)
> 
> Finally, patch 8 tries to avoid userdata values in host byte order by
> storing u32 values in Big Endian. Since nftnl_udata_put_u32() is the
> only typed attribute setter (apart from the unproblematic strz one),
> this may be good enough for the purpose.
> 
> Phil Sutter (9):
>   set_elem: Review debug output
>   expr: data_reg: Avoid extra whitespace
>   expr: Pass byteorder to struct expr_ops::set callback
>   data_reg: Introduce struct nftnl_data_reg::byteorder field
>   data_reg: Introduce struct nftnl_data_reg::sizes array
>   Introduce nftnl_{expr,set_elem}_set_imm()
>   data_reg: Respect data byteorder when printing
>   data_reg: Support concatenated data
>   udata: Store u32 udata values in Big Endian

Series applied.