From 1ce8986798f2003a9b2084a987971deedf52228e Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Thu, 23 May 2013 13:32:42 +0200
Subject: [PATCH] Use weak function pointers to call extension init functions,
 this makes firewall3 independant from the features compiled into iptables

---
 iptables.c | 33 +++++++++-----------------------
 iptables.h | 56 +++++++++++++++++++++++++++++++-----------------------
 2 files changed, 41 insertions(+), 48 deletions(-)

diff --git a/iptables.c b/iptables.c
index 56f68c3..f39ed1e 100644
--- a/iptables.c
+++ b/iptables.c
@@ -54,32 +54,17 @@ get_kernel_version(void)
 	kernel_version = LINUX_VERSION(x, y, z);
 }
 
+#undef __ipt_module
+#define __ipt_module(x) libxt_##x##_init, libipt_##x##_init, libip6t_##x##_init,
+
 static void fw3_init_extensions(void)
 {
-	libip6t_icmp6_init();
-	libip6t_LOG_init();
-	libip6t_REJECT_init();
-	libipt_DNAT_init();
-	libipt_icmp_init();
-	libipt_LOG_init();
-	libipt_MASQUERADE_init();
-	libipt_REDIRECT_init();
-	libipt_REJECT_init();
-	libipt_SNAT_init();
-	libxt_comment_init();
-	libxt_conntrack_init();
-	libxt_CT_init();
-	libxt_limit_init();
-	libxt_mac_init();
-	libxt_mark_init();
-	libxt_MARK_init();
-	libxt_set_init();
-	libxt_SET_init();
-	libxt_standard_init();
-	libxt_TCPMSS_init();
-	libxt_tcp_init();
-	libxt_time_init();
-	libxt_udp_init();
+	int i;
+	void (*initfuncs[])(void) = { FW3_IPT_MODULES };
+
+	for (i = 0; i < sizeof(initfuncs)/sizeof(initfuncs[0]); i++)
+		if (initfuncs[i])
+			initfuncs[i]();
 }
 
 struct fw3_ipt_handle *
diff --git a/iptables.h b/iptables.h
index cee9cc4..c8c86ec 100644
--- a/iptables.h
+++ b/iptables.h
@@ -34,30 +34,38 @@ extern struct xtables_match *xtables_pending_matches;
 extern struct xtables_target *xtables_pending_targets;
 
 /* libext.a interface */
-void libip6t_icmp6_init(void);
-void libip6t_LOG_init(void);
-void libip6t_REJECT_init(void);
-void libipt_DNAT_init(void);
-void libipt_icmp_init(void);
-void libipt_LOG_init(void);
-void libipt_MASQUERADE_init(void);
-void libipt_REDIRECT_init(void);
-void libipt_REJECT_init(void);
-void libipt_SNAT_init(void);
-void libxt_comment_init(void);
-void libxt_conntrack_init(void);
-void libxt_CT_init(void);
-void libxt_limit_init(void);
-void libxt_mac_init(void);
-void libxt_mark_init(void);
-void libxt_MARK_init(void);
-void libxt_set_init(void);
-void libxt_SET_init(void);
-void libxt_standard_init(void);
-void libxt_TCPMSS_init(void);
-void libxt_tcp_init(void);
-void libxt_time_init(void);
-void libxt_udp_init(void);
+#define FW3_IPT_MODULES			\
+	__ipt_module(comment)		\
+	__ipt_module(conntrack)		\
+	__ipt_module(icmp)			\
+	__ipt_module(icmp6)			\
+	__ipt_module(limit)			\
+	__ipt_module(mac)			\
+	__ipt_module(mark)			\
+	__ipt_module(set)			\
+	__ipt_module(standard)		\
+	__ipt_module(tcp)			\
+	__ipt_module(time)			\
+	__ipt_module(udp)			\
+	__ipt_module(CT)			\
+	__ipt_module(DNAT)			\
+	__ipt_module(LOG)			\
+	__ipt_module(MARK)			\
+	__ipt_module(MASQUERADE)	\
+	__ipt_module(REDIRECT)		\
+	__ipt_module(REJECT)		\
+	__ipt_module(SET)			\
+	__ipt_module(SNAT)			\
+	__ipt_module(TCPMSS)
+
+#undef __ipt_module
+#define __ipt_module(x) \
+	extern void libxt_##x##_init(void) __attribute__((weak)); \
+	extern void libipt_##x##_init(void) __attribute__((weak)); \
+	extern void libip6t_##x##_init(void) __attribute__((weak));
+
+FW3_IPT_MODULES
+
 
 /* Required by certain extensions like SNAT and DNAT */
 extern int kernel_version;
-- 
2.25.1