[iptables PATCH v2 13/17] xtables: arptables doesn't warn about empty interface

[Phil Sutter <phil@nwl.cc>]

The empty string passed as interface name is simply ignored. Calling
xtables_parse_interface() with an empty string is safe.

Note that arptables-legacy seems not to ignore inverted empty
interfacess, they appear in '-L' output as such:

| -j ACCEPT -i * ! -o * , pcnt=0 -- bcnt=0

Yet they don't appear in arptables-save output. Given that inverted "any
interface" will never match, there's probably no point in sticking to
this inconsistency.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 iptables/xtables.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/iptables/xtables.c b/iptables/xtables.c
index 23d7d29169ca0..5b5c875dc3a6c 100644
--- a/iptables/xtables.c
+++ b/iptables/xtables.c
@@ -533,7 +533,7 @@ void do_parse(struct nft_handle *h, int argc, char *argv[],
 			break;
 
 		case 'i':
-			if (*optarg == '\0')
+			if (*optarg == '\0' && h->family != NFPROTO_ARP)
 				xtables_error(PARAMETER_PROBLEM,
 					"Empty interface is likely to be "
 					"undesired");
@@ -545,7 +545,7 @@ void do_parse(struct nft_handle *h, int argc, char *argv[],
 			break;
 
 		case 'o':
-			if (*optarg == '\0')
+			if (*optarg == '\0' && h->family != NFPROTO_ARP)
 				xtables_error(PARAMETER_PROBLEM,
 					"Empty interface is likely to be "
 					"undesired");
-- 
2.33.0