add bsn_tcp_flags extension

This extension adds an OXM to support matching on TCP flags.
diff --git a/openflow_input/bsn_tcp_flags b/openflow_input/bsn_tcp_flags
new file mode 100644
index 0000000..e8ef2e9
--- /dev/null
+++ b/openflow_input/bsn_tcp_flags
@@ -0,0 +1,59 @@
+// Copyright 2014, Big Switch Networks, Inc.
+//
+// LoxiGen is licensed under the Eclipse Public License,
+// version 1.0 (EPL), with the following special exception:
+//
+// LOXI Exception
+//
+// As a special exception to the terms of the EPL, you may
+// distribute libraries generated by LoxiGen (LoxiGen Libraries)
+// under the terms of your choice, provided that copyright and
+// licensing notices generated by LoxiGen are not altered or removed
+// from the LoxiGen Libraries and the notice provided below is (i)
+// included in the LoxiGen Libraries, if distributed in source code
+// form and (ii) included in any documentation for the LoxiGen
+// Libraries, if distributed in binary form.
+//
+// Notice: "Copyright 2013, Big Switch Networks, Inc.
+// This library was generated by the LoxiGen Compiler."
+//
+// You may not use this file except in compliance with the EPL or
+// LOXI Exception. You may obtain a copy of the EPL at:
+//
+// http://www.eclipse.org/legal/epl-v10.html
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an "AS
+// IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied. See the EPL for the specific language
+// governing permissions and limitations under the EPL.
+
+#version 3
+#version 4
+
+/*
+ * TCP flags
+ */
+
+enum ofp_bsn_tcp_flag(wire_type=uint16_t, bitmask=True) {
+    OFP_BSN_TCP_FLAG_FIN = 0x001,
+    OFP_BSN_TCP_FLAG_SYN = 0x002,
+    OFP_BSN_TCP_FLAG_RST = 0x004,
+    OFP_BSN_TCP_FLAG_PSH = 0x008,
+    OFP_BSN_TCP_FLAG_ACK = 0x010,
+    OFP_BSN_TCP_FLAG_URG = 0x020,
+    OFP_BSN_TCP_FLAG_ECE = 0x040,
+    OFP_BSN_TCP_FLAG_CWR = 0x080,
+    OFP_BSN_TCP_FLAG_NS  = 0x100,
+};
+
+struct of_oxm_bsn_tcp_flags : of_oxm {
+    uint32_t type_len == 0x00032002;
+    uint16_t value;
+};
+
+struct of_oxm_bsn_tcp_flags_masked : of_oxm {
+    uint32_t type_len == 0x00032104;
+    uint16_t value;
+    uint16_t value_mask;
+};