[iptables PATCH 3/3] extensions: TCPOPTSTRIP: Do not print empty options

[Phil Sutter <phil@nwl.cc>]

No point in printing anything if none of the bits are set.

Fixes: aef4c1e727563 ("libxt_TCPOPTSTRIP")
Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 extensions/libxt_TCPOPTSTRIP.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/extensions/libxt_TCPOPTSTRIP.c b/extensions/libxt_TCPOPTSTRIP.c
index 6ea3489224602..ff873f98b3aaa 100644
--- a/extensions/libxt_TCPOPTSTRIP.c
+++ b/extensions/libxt_TCPOPTSTRIP.c
@@ -142,6 +142,13 @@ tcpoptstrip_print_list(const struct xt_tcpoptstrip_target_info *info,
 	}
 }
 
+static bool tcpoptstrip_empty(const struct xt_tcpoptstrip_target_info *info)
+{
+	static const struct xt_tcpoptstrip_target_info empty = {};
+
+	return memcmp(info, &empty, sizeof(empty)) == 0;
+}
+
 static void
 tcpoptstrip_tg_print(const void *ip, const struct xt_entry_target *target,
                      int numeric)
@@ -149,6 +156,9 @@ tcpoptstrip_tg_print(const void *ip, const struct xt_entry_target *target,
 	const struct xt_tcpoptstrip_target_info *info =
 		(const void *)target->data;
 
+	if (tcpoptstrip_empty(info))
+		return;
+
 	printf(" TCPOPTSTRIP options ");
 	tcpoptstrip_print_list(info, numeric);
 }
@@ -159,6 +169,9 @@ tcpoptstrip_tg_save(const void *ip, const struct xt_entry_target *target)
 	const struct xt_tcpoptstrip_target_info *info =
 		(const void *)target->data;
 
+	if (tcpoptstrip_empty(info))
+		return;
+
 	printf(" --strip-options ");
 	tcpoptstrip_print_list(info, true);
 }
-- 
2.34.1