ofproto/nx_match: various minor clean up

- initialize Flow.tun_id
- avoid name clash with _set_nxm_headers
- eliminated duplicated MFTPSRC
- s/len/len_/ to avoid name clash with builtin len()

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/ofproto/nx_match.py

@@ -79,6 +79,7 @@ def __init__(self):
         self.arp_tha = 0
         self.nw_src = 0
         self.nw_dst = 0
+        self.tun_id = 0
 
 
 class FlowWildcards(object):
@@ -236,10 +237,10 @@ def match_tuple(self):
 
 def _set_nxm_headers(nxm_headers):
     '''Annotate corresponding NXM header'''
-    def _set_nxm_headers(self):
+    def _set_nxm_headers_dec(self):
         self.nxm_headers = nxm_headers
         return self
-    return _set_nxm_headers
+    return _set_nxm_headers_dec
 
 
 def _register_make(cls):
@@ -271,8 +272,8 @@ def _put(self, buf, offset, value):
         return self.n_bytes
 
     def putw(self, buf, offset, value, mask):
-        len = self._put(buf, offset, value)
-        return len + self._put(buf, offset + len, mask)
+        len_ = self._put(buf, offset, value)
+        return len + self._put(buf, offset + len_, mask)
 
     def _is_all_ones(self, value):
         return value == (1 << self.n_bits) - 1
@@ -442,18 +443,6 @@ def put(self, buf, offset, rule):
         return self.putm(buf, offset, rule.flow.tp_src, rule.wc.tp_src_mask)
 
 
-@_register_make
-@_set_nxm_headers([ofproto_v1_0.NXM_OF_TCP_DST, ofproto_v1_0.NXM_OF_TCP_DST_W,
-                   ofproto_v1_0.NXM_OF_UDP_DST, ofproto_v1_0.NXM_OF_UDP_DST_W])
-class MFTPSRC(MFField):
-    @classmethod
-    def make(cls):
-        return cls(MF_PACK_STRING_BE16)
-
-    def put(self, buf, offset, rule):
-        return self.putm(buf, offset, rule.flow.tp_dst, rule.wc.tp_dst_mask)
-
-
 @_register_make
 @_set_nxm_headers([ofproto_v1_0.NXM_NX_ARP_SHA])
 class MFArpSha(MFField):
@@ -623,9 +612,9 @@ def serialize_nxm_match(rule, buf, offset):
 
 def nxm_put(buf, offset, header, rule):
     nxm = NXMatch(header)
-    len = nxm.put_header(buf, offset)
+    len_ = nxm.put_header(buf, offset)
     mf = mf_from_nxm_header(nxm.header)
-    return len + mf.put(buf, offset + len, rule)
+    return len_ + mf.put(buf, offset + len, rule)
 
 
 def round_up(length):