packet lib: set _MIN_LEN class variable

All protocols need to check if the data length is long enough so let's
set the minimum length in the same way.

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

6 files changed, 12 insertions, 9 deletions

diff --git a/ryu/lib/packet/arp.py b/ryu/lib/packet/arp.py
index f71d5657..24ba2c02 100644
--- a/ryu/lib/packet/arp.py
+++ b/ryu/lib/packet/arp.py
@@ -19,6 +19,7 @@ from . import packet_base
 
 class arp(packet_base.PacketBase):
     _PACK_STR = '!HHBBH6sI6sI'
+    _MIN_LEN = struct.calcsize(_PACK_STR)
 
     def __init__(self, hwtype, proto, hlen, plen, opcode,
                  src_mac, src_ip, dst_mac, dst_ip):
@@ -32,7 +33,7 @@ class arp(packet_base.PacketBase):
         self.src_ip = src_ip
         self.dst_mac = dst_mac
         self.dst_ip = dst_ip
-        self.length = struct.calcsize(arp._PACK_STR)
+        self.length = arp._MIN_LEN
 
     @classmethod
     def parser(cls, buf):
diff --git a/ryu/lib/packet/ethernet.py b/ryu/lib/packet/ethernet.py
index adb706a0..de034562 100644
--- a/ryu/lib/packet/ethernet.py
+++ b/ryu/lib/packet/ethernet.py
@@ -21,13 +21,14 @@ from ryu.ofproto import ether
 
 class ethernet(packet_base.PacketBase):
     _PACK_STR = '!6s6sH'
+    _MIN_LEN = struct.calcsize(_PACK_STR)
 
     def __init__(self, dst, src, ethertype):
         super(ethernet, self).__init__()
         self.dst = dst
         self.src = src
         self.ethertype = ethertype
-        self.length = struct.calcsize(ethernet._PACK_STR)
+        self.length = ethernet._MIN_LEN
 
     @classmethod
     def parser(cls, buf):
diff --git a/ryu/lib/packet/ipv4.py b/ryu/lib/packet/ipv4.py
index bd7b6330..93c38285 100644
--- a/ryu/lib/packet/ipv4.py
+++ b/ryu/lib/packet/ipv4.py
@@ -23,6 +23,7 @@ from ryu.ofproto import inet
 
 class ipv4(packet_base.PacketBase):
     _PACK_STR = '!BBHHHBBHII'
+    _MIN_LEN = struct.calcsize(_PACK_STR)
 
     def __init__(self, version, header_length, tos, total_length,
                  identification, flags, offset, ttl, proto, csum,
@@ -53,8 +54,8 @@ class ipv4(packet_base.PacketBase):
         msg = cls(version, header_length, tos, total_length, identification,
                   flags, offset, ttl, proto, csum, src, dst)
 
-        if msg.length > struct.calcsize(ipv4._PACK_STR):
-            self.extra = buf[struct.calcsize(ipv4._PACK_STR):msg.length]
+        if msg.length > ipv4._MIN_LEN:
+            self.extra = buf[ipv4._MIN_LEN:msg.length]
 
         return msg, ipv4.get_packet_type(proto)
 
diff --git a/ryu/lib/packet/tcp.py b/ryu/lib/packet/tcp.py
index 975bfcca..73e700db 100644
--- a/ryu/lib/packet/tcp.py
+++ b/ryu/lib/packet/tcp.py
@@ -22,6 +22,7 @@ import ipv4
 
 class tcp(packet_base.PacketBase):
     _PACK_STR = '!HHIIBBHHH'
+    _MIN_LEN = struct.calcsize(_PACK_STR)
 
     def __init__(self, src_port, dst_port, seq, ack, offset,
                  bits, window_size, csum, urgent):
diff --git a/ryu/lib/packet/udp.py b/ryu/lib/packet/udp.py
index 6fc84fc1..2b858d98 100644
--- a/ryu/lib/packet/udp.py
+++ b/ryu/lib/packet/udp.py
@@ -22,6 +22,7 @@ import ipv4
 
 class udp(packet_base.PacketBase):
     _PACK_STR = '!HHHH'
+    _MIN_LEN = struct.calcsize(_PACK_STR)
 
     def __init__(self, src_port, dst_port, length, csum=0):
         super(udp, self).__init__()
@@ -35,14 +36,11 @@ class udp(packet_base.PacketBase):
         (src_port, dst_port, length, csum) = struct.unpack_from(cls._PACK_STR,
                                                                 buf)
         msg = cls(src_port, dst_port, length, csum)
-        if length > struct.calcsize(cls._PACK_STR):
-            msg.data = buf[struct.calcsize(cls._PACK_STR):length]
-
         return msg, None
 
     def serialize(self, payload, prev):
         if self.length == 0:
-            self.length = struct.calcsize(udp._PACK_STR) + len(payload)
+            self.length = udp._MIN_LEN + len(payload)
         h = struct.pack(udp._PACK_STR, self.src_port, self.dst_port,
                         self.length, self.csum)
         if self.csum == 0:
diff --git a/ryu/lib/packet/vlan.py b/ryu/lib/packet/vlan.py
index bc33f2ff..4fb93a19 100644
--- a/ryu/lib/packet/vlan.py
+++ b/ryu/lib/packet/vlan.py
@@ -23,6 +23,7 @@ from ryu.ofproto.ofproto_parser import msg_pack_into
 
 class vlan(packet_base.PacketBase):
     _PACK_STR = "!HH"
+    _MIN_LEN = struct.calcsize(_PACK_STR)
 
     def __init__(self, pcp, cfi, vid, ethertype):
         super(vlan, self).__init__()
@@ -30,7 +31,7 @@ class vlan(packet_base.PacketBase):
         self.cfi = cfi
         self.vid = vid
         self.ethertype = ethertype
-        self.length = struct.calcsize(vlan._PACK_STR)
+        self.length = vlan._MIN_LEN
 
     @classmethod
     def parser(cls, buf):