conntrackd: add cthelper infrastructure (+ example FTP helper)

This patch adds the user-space helper infrastructure. It also
contains the implementation of the FTP helper in user-space.

There's one example file that you can use to configure conntrackd
as user-space connection tracking helper under:

 doc/helper/conntrackd.conf

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/include/myct.h b/include/myct.h
new file mode 100644
index 0000000..45d9f29
--- /dev/null
+++ b/include/myct.h
@@ -0,0 +1,43 @@
+#ifndef _MYCT_H_
+#define _MYCT_H_
+
+#include "linux_list.h"
+
+#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
+
+struct nf_conntrack;
+
+enum {
+	MYCT_NONE		= 0,
+	MYCT_ESTABLISHED	= (1 << 0),
+};
+
+enum {
+	MYCT_DIR_ORIG = 0,
+	MYCT_DIR_REPL,
+	MYCT_DIR_MAX,
+};
+
+union myct_proto {
+	uint16_t port;
+	uint16_t all;
+};
+
+struct myct_man {
+	union nfct_attr_grp_addr u3;
+	union myct_proto	u;
+	uint16_t		l3num;
+	uint8_t			protonum;
+};
+
+struct myct_tuple {
+	struct myct_man		src;
+	struct myct_man		dst;
+};
+
+struct myct {
+	struct nf_conntrack *ct;
+	void *priv_data;
+};
+
+#endif