Re: [PATCH net v2] net: netfilter: Fix port selection of FTP for NF_NAT_RANGE_PROTO_SPECIFIED

[Jan Engelhardt]

On Tuesday 2021-09-07 15:54, Florian Westphal wrote:
>> -	/* Try to get same port: if not, try to change it. */
>> -	for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
>> -		int ret;
>> +	if (htons(nat->range_info.min_proto.all) == 0 ||
>> +	    htons(nat->range_info.max_proto.all) == 0) {
>
>Either use if (nat->range_info.min_proto.all || ...
>
>or use ntohs().  I will leave it up to you if you prefer
>ntohs(nat->range_info.min_proto.all) == 0 or
>nat->range_info.min_proto.all == ntohs(0).

If one has the option, one should always prefer to put htons/htonl on 
the side with the constant literal;
Propagation of constants and compile-time evaluation is the target.

That works for some other functions as well (e.g. 
strlen("fixedstring")).