Improved how NAT-T keepalives are handled in sockets/receiver.

src/libcharon/network/receiver.c

@@ -417,6 +417,7 @@ static job_requeue_t receive_packets(private_receiver_t *this)
 	host_t *src, *dst;
 	status_t status;
 	bool supported = TRUE;
+	chunk_t data, marker = chunk_from_chars(0x00, 0x00, 0x00, 0x00);
 
 	/* read in a packet */
 	status = charon->socket->receive(charon->socket, &packet);
@@ -430,6 +431,19 @@ static job_requeue_t receive_packets(private_receiver_t *this)
 		return JOB_REQUEUE_FAIR;
 	}
 
+	data = packet->get_data(packet);
+	if (data.len == 1 && data.ptr[0] == 0xFF)
+	{	/* silently drop NAT-T keepalives */
+		packet->destroy(packet);
+		return JOB_REQUEUE_DIRECT;
+	}
+	else if (data.len < marker.len)
+	{	/* drop packets that are too small */
+		DBG3(DBG_NET, "received packet is too short (%d bytes)", data.len);
+		packet->destroy(packet);
+		return JOB_REQUEUE_DIRECT;
+	}
+
 	/* if neither source nor destination port is 500 we assume an IKE packet
 	 * with Non-ESP marker or an ESP packet */
 	dst = packet->get_destination(packet);
@@ -437,9 +451,6 @@ static job_requeue_t receive_packets(private_receiver_t *this)
 	if (dst->get_port(dst) != IKEV2_UDP_PORT &&
 		src->get_port(src) != IKEV2_UDP_PORT)
 	{
-		chunk_t marker = chunk_from_chars(0x00, 0x00, 0x00, 0x00), data;
-
-		data = packet->get_data(packet);
 		if (memeq(data.ptr, marker.ptr, marker.len))
 		{	/* remove Non-ESP marker */
 			data = chunk_skip(data, marker.len);

src/libcharon/plugins/socket_default/socket_default_socket.c

@@ -48,9 +48,6 @@
 /* Maximum size of a packet */
 #define MAX_PACKET 10000
 
-/* length of non-esp marker */
-#define MARKER_LEN sizeof(u_int32_t)
-
 /* these are not defined on some platforms */
 #ifndef SOL_IP
 #define SOL_IP IPPROTO_IP
@@ -207,13 +204,6 @@ METHOD(socket_t, receiver, status_t,
 		}
 		DBG3(DBG_NET, "received packet %b", buffer, bytes_read);
 
-		if (bytes_read < MARKER_LEN)
-		{
-			DBG3(DBG_NET, "received packet too short (%d bytes)",
-				 bytes_read);
-			return FAILED;
-		}
-
 		/* read ancillary data to get destination address */
 		for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL;
 			 cmsgptr = CMSG_NXTHDR(&msg, cmsgptr))

src/libcharon/plugins/socket_dynamic/socket_dynamic_socket.c

@@ -45,9 +45,6 @@
 /* Maximum size of a packet */
 #define MAX_PACKET 10000
 
-/* length of non-esp marker */
-#define MARKER_LEN sizeof(u_int32_t)
-
 /* these are not defined on some platforms */
 #ifndef SOL_IP
 #define SOL_IP IPPROTO_IP
@@ -225,12 +222,6 @@ static packet_t *receive_packet(private_socket_dynamic_socket_t *this,
 	}
 	DBG3(DBG_NET, "received packet %b", buffer, (u_int)len);
 
-	if (len < MARKER_LEN)
-	{
-		DBG3(DBG_NET, "received packet too short (%d bytes)", len);
-		return NULL;
-	}
-
 	/* read ancillary data to get destination address */
 	for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL;
 		 cmsgptr = CMSG_NXTHDR(&msg, cmsgptr))

src/libcharon/plugins/socket_raw/socket_raw_socket.c

@@ -172,7 +172,7 @@ METHOD(socket_t, receiver, status_t,
 		DBG3(DBG_NET, "received IPv4 packet %b", buffer, bytes_read);
 
 		/* read source/dest from raw IP/UDP header */
-		if (bytes_read < IP_LEN + UDP_LEN + MARKER_LEN)
+		if (bytes_read < IP_LEN + UDP_LEN)
 		{
 			DBG1(DBG_NET, "received IPv4 packet too short (%d bytes)",
 				 bytes_read);
@@ -226,7 +226,7 @@ METHOD(socket_t, receiver, status_t,
 		}
 		DBG3(DBG_NET, "received IPv6 packet %b", buffer, bytes_read);
 
-		if (bytes_read < IP_LEN + UDP_LEN + MARKER_LEN)
+		if (bytes_read < IP_LEN + UDP_LEN)
 		{
 			DBG3(DBG_NET, "received IPv6 packet too short (%d bytes)",
 				 bytes_read);