On Sat, Aug 16, 2008 at 6:44 AM, Jozsef Kadlecsik
<kadlec@xxxxxxxxxxxxxxxxx> wrote:
> On Fri, 15 Aug 2008, Jan Engelhardt wrote:
>
>>
>> On Friday 2008-08-15 16:48, Jozsef Kadlecsik wrote:
>> >> - ecn and ECN
>> >
>> >The options of the ecn match and the ECN target are not clashing.
>>
>> They do. Both libipt_ecn.c and libipt_ECN.c have --ecn-ip-ect,
>> --ecn-tcp-cwr and --ecn-tcp-ece even if they are not documented
>> (what, more of these? Patch follows).
>
> Non-documented options do not exist ;-) - so updates are highly welcomed.
>
> But as the ECN options has not been documented so far, I think it'd be
> better to rename them at the same time to something like
>
> --ecn-tcp-cwr-remove
> --ecn-tcp-ece-remove
> --ecn-ip-ect-set
>
> and clashing with the ecn options were resolved.
It sounds a good idae. But in order to avoid clashing, we'd better
change all the options for all matches in this way:
match: foo
match-options: --foo-bar
I don't mean that some maches share the same options is encouraged,
but I don't think it lose readable, as I think most of people will
think the long options after a "-m" option until another match appears
with the leading "-m" are all for this corresponding match. Global
option naming space allow commands like this:
iptables ... -m a --a-option-1 -m b --b-option-1 --a-option-2
Oh, I think it make the command unreadable, and we should not allow it happen.
I encountered this issue when I debugging a match. Its parse function
is like this:
parse(...)
{
if (*flags)
error...;
switch (c) {
case 'a':
....
break;
default:
return 0;
}
*flags = 1;
return 1;
}
it will fail if there is another kinds of match after it, as all the
options not belong to it are parsed to its parse function. I think it
is the reason why default branch in switch exists. I make things a
little different from my original thought.
When writting this, I get another idea to solve this. Before calling
the parse function, we should check if c is in the option range with
one line code:
c > m->option_offset && c < m->option_offset + OPTION_OFFSET
--
Regards，
Changli Gao(xiaosuo@xxxxxxxxx)
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