From cd2f9bdbb7f9b737e5d640aafeb78bcd8e3a7adf Mon Sep 17 00:00:00 2001 From: Jan Engelhardt Date: Tue, 4 Sep 2012 05:24:47 +0200 Subject: iptables: support for target aliases This patch allows for target names listed on the command line to be rewritten to new names and revisions. As before, we will pick a revision that is supported by the kernel - now including real_name in the search. This gives us the possibility to test for many action names. Signed-off-by: Jan Engelhardt --- libxtables/xtables.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) (limited to 'libxtables') diff --git a/libxtables/xtables.c b/libxtables/xtables.c index 7f0d3ccb..a2b24c5a 100644 --- a/libxtables/xtables.c +++ b/libxtables/xtables.c @@ -872,9 +872,18 @@ void xtables_register_match(struct xtables_match *me) * preferred. */ static int -xtables_mt_prefer(unsigned int a_rev, unsigned int a_fam, - unsigned int b_rev, unsigned int b_fam) +xtables_mt_prefer(bool a_alias, unsigned int a_rev, unsigned int a_fam, + bool b_alias, unsigned int b_rev, unsigned int b_fam) { + /* + * Alias ranks higher than no alias. + * (We want the new action to be used whenever possible.) + */ + if (!a_alias && b_alias) + return -1; + if (a_alias && !b_alias) + return 1; + /* Higher revision ranks higher. */ if (a_rev < b_rev) return -1; @@ -894,14 +903,21 @@ xtables_mt_prefer(unsigned int a_rev, unsigned int a_fam, static int xtables_match_prefer(const struct xtables_match *a, const struct xtables_match *b) { - return xtables_mt_prefer(a->revision, a->family, - b->revision, b->family); + return xtables_mt_prefer(false, a->revision, a->family, + false, b->revision, b->family); } static int xtables_target_prefer(const struct xtables_target *a, const struct xtables_target *b) { - return xtables_mt_prefer(a->revision, a->family, + /* + * Note that if x->real_name==NULL, it will be set to x->name in + * xtables_register_*; the direct pointer comparison here is therefore + * legitimate to detect an alias. + */ + return xtables_mt_prefer(a->name != a->real_name, + a->revision, a->family, + b->name != b->real_name, b->revision, b->family); } @@ -985,6 +1001,8 @@ void xtables_register_target(struct xtables_target *me) exit(1); } + if (me->real_name == NULL) + me->real_name = me->name; if (me->x6_options != NULL) xtables_option_metavalidate(me->name, me->x6_options); if (me->extra_opts != NULL) @@ -1018,11 +1036,11 @@ static void xtables_fully_register_pending_target(struct xtables_target *me) /* Now we have two (or more) options, check compatibility. */ if (compare > 0 && - compatible_target_revision(old->name, old->revision)) + compatible_target_revision(old->real_name, old->revision)) return; /* See if new target can be used. */ - if (!compatible_target_revision(me->name, me->revision)) + if (!compatible_target_revision(me->real_name, me->revision)) return; /* Delete old one. */ -- cgit v1.2.3