1 files changed, 88 insertions, 0 deletions
diff --git a/l4_udp.c b/l4_udp.c
new file mode 100755
index 0000000..4d52d0a
--- /dev/null
+++ b/l4_udp.c
@@ -0,0 +1,88 @@
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+
+#include "proto.h"
+
+#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
+
+#define PRINT_CMP(...)
+
+static void l4_udp_ct_build_tuple(const uint8_t *pkt, struct nf_conntrack *ct)
+{
+	const struct udphdr *udph = (const struct udphdr *)pkt;
+
+	nfct_set_attr_u8(ct, ATTR_ORIG_L4PROTO, IPPROTO_UDP);
+	nfct_set_attr_u8(ct, ATTR_REPL_L4PROTO, IPPROTO_UDP);
+	nfct_set_attr_u16(ct, ATTR_ORIG_PORT_SRC, udph->source);
+	nfct_set_attr_u16(ct, ATTR_ORIG_PORT_DST, udph->dest);
+	nfct_set_attr_u16(ct, ATTR_REPL_PORT_SRC, udph->dest);
+	nfct_set_attr_u16(ct, ATTR_REPL_PORT_DST, udph->source);
+}
+
+static int l4_udp_ct_cmp_tuple_orig(const uint8_t *pkt, struct nf_conntrack *ct)
+{
+	const struct udphdr *udph = (const struct udphdr *)pkt;
+
+	PRINT_CMP("cmp_orig udph->source: %u == %u\n",
+		udph->source, nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC));
+	PRINT_CMP("cmp_orig udph->dest: %u == %u\n",
+		udph->dest, nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST));
+
+	if (udph->source == nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC) &&
+	    udph->dest == nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST))
+		return 1;
+
+	return 0;
+}
+
+static int
+l4_udp_ct_cmp_tuple_repl(const uint8_t *pkt, struct nf_conntrack *ct)
+{
+	const struct udphdr *udph = (const struct udphdr *)pkt;
+
+	PRINT_CMP("cmp_repl udph->source: %u == %u\n",
+		udph->source, nfct_get_attr_u16(ct, ATTR_REPL_PORT_SRC));
+	PRINT_CMP("cmp_repl udph->dest: %u == %u\n",
+		udph->dest, nfct_get_attr_u16(ct, ATTR_REPL_PORT_DST));
+
+	if (udph->source == nfct_get_attr_u16(ct, ATTR_REPL_PORT_SRC) &&
+	    udph->dest == nfct_get_attr_u16(ct, ATTR_REPL_PORT_DST))
+		return 1;
+
+	return 0;
+}
+
+static int
+l4_udp_ct_cmp_port(struct nf_conntrack *ct, uint16_t port)
+{
+	PRINT_CMP("cmp_port src: %u == %u\n",
+		port, nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC));
+	PRINT_CMP("cmp_port dst: %u == %u\n",
+		port, nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST));
+
+	if (port == nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC) ||
+	    port == nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST))
+		return 1;
+
+	return 0;
+}
+
+static int l4_udp_pkt_no_data(const uint8_t *pkt)
+{
+	/* UDP has no control packets. */
+	return 1;
+}
+
+static struct cthelper_proto_l4_helper tcp = {
+	.l4protonum	= IPPROTO_UDP,
+	.l4ct_build	= l4_udp_ct_build_tuple,
+	.l4ct_cmp_orig	= l4_udp_ct_cmp_tuple_orig,
+	.l4ct_cmp_repl	= l4_udp_ct_cmp_tuple_repl,
+	.l4ct_cmp_port	= l4_udp_ct_cmp_port,
+	.l4pkt_no_data	= l4_udp_pkt_no_data,
+};
+
+void l4_udp_init(void)
+{
+	cthelper_proto_l4_helper_register(&tcp);
+}