os-ken/ryu/ofproto/ofproto_parser.py
YAMAMOTO Takashi 71ea304be6 add some docstring on StringifyMixin and relevant code
Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
2013-09-20 09:40:53 +09:00

229 lines
6.7 KiB
Python

# Copyright (C) 2011, 2012 Nippon Telegraph and Telephone Corporation.
# Copyright (C) 2011 Isaku Yamahata <yamahata at valinux co jp>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# 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 License for the specific language governing permissions and
# limitations under the License.
import collections
import logging
import struct
import sys
import functools
from ryu import exception
from ryu.lib import stringify
from . import ofproto_common
LOG = logging.getLogger('ryu.ofproto.ofproto_parser')
def header(buf):
assert len(buf) >= ofproto_common.OFP_HEADER_SIZE
#LOG.debug('len %d bufsize %d', len(buf), ofproto.OFP_HEADER_SIZE)
return struct.unpack_from(ofproto_common.OFP_HEADER_PACK_STR, buffer(buf))
_MSG_PARSERS = {}
def register_msg_parser(version):
def register(msg_parser):
_MSG_PARSERS[version] = msg_parser
return msg_parser
return register
def msg(datapath, version, msg_type, msg_len, xid, buf):
assert len(buf) >= msg_len
msg_parser = _MSG_PARSERS.get(version)
if msg_parser is None:
raise exception.OFPUnknownVersion(version=version)
return msg_parser(datapath, version, msg_type, msg_len, xid, buf)
def create_list_of_base_attributes(f):
@functools.wraps(f)
def wrapper(self, *args, **kwargs):
ret = f(self, *args, **kwargs)
cls = self.__class__
# hasattr(cls, '_base_attributes') doesn't work because super class
# may already have the attribute.
if '_base_attributes' not in cls.__dict__:
cls._base_attributes = set(dir(self))
return ret
return wrapper
def ofp_msg_from_jsondict(dp, jsondict):
"""
This function instanticates an appropriate OpenFlow message class
from the given JSON style dictionary.
The objects created by following two code fragments are equivalent.
Code A::
jsonstr = '{ "OFPSetConfig": { "flags": 0, "miss_send_len": 128 } }'
jsondict = json.loads(jsonstr)
o = ofp_msg_from_jsondict(dp, jsondict)
Code B::
o = dp.ofproto_parser.OFPSetConfig(flags=0, miss_send_len=128)
This function takes the following arguments.
======== =======================================
Argument Description
======== =======================================
dp An instance of ryu.controller.Datapath.
jsondict A JSON style dict.
======== =======================================
"""
parser = dp.ofproto_parser
assert len(jsondict) == 1
for k, v in jsondict.iteritems():
cls = getattr(parser, k)
assert issubclass(cls, MsgBase)
return cls.from_jsondict(v, datapath=dp)
class StringifyMixin(stringify.StringifyMixin):
_class_prefixes = ["OFP", "MT"]
@classmethod
def cls_from_jsondict_key(cls, k):
obj_cls = super(StringifyMixin, cls).cls_from_jsondict_key(k)
assert not issubclass(obj_cls, MsgBase)
return obj_cls
class MsgBase(StringifyMixin):
"""
This is a base class for OpenFlow message classes.
An instance of this class has at least the following attributes.
========= ==============================
Attribute Description
========= ==============================
datapath A ryu.controller.controller.Datapath instance for this message
version OpenFlow protocol version
msg_type Type of OpenFlow message
msg_len Length of the message
xid Transaction id
buf Raw data
========= ==============================
"""
@create_list_of_base_attributes
def __init__(self, datapath):
super(MsgBase, self).__init__()
self.datapath = datapath
self.version = None
self.msg_type = None
self.msg_len = None
self.xid = None
self.buf = None
def set_headers(self, version, msg_type, msg_len, xid):
assert msg_type == self.cls_msg_type
self.version = version
self.msg_type = msg_type
self.msg_len = msg_len
self.xid = xid
def set_xid(self, xid):
assert self.xid is None
self.xid = xid
def set_buf(self, buf):
self.buf = buffer(buf)
def __str__(self):
buf = 'version: 0x%x msg_type 0x%x xid 0x%x ' % (self.version,
self.msg_type,
self.xid)
return buf + StringifyMixin.__str__(self)
@classmethod
def parser(cls, datapath, version, msg_type, msg_len, xid, buf):
msg_ = cls(datapath)
msg_.set_headers(version, msg_type, msg_len, xid)
msg_.set_buf(buf)
return msg_
def _serialize_pre(self):
self.version = self.datapath.ofproto.OFP_VERSION
self.msg_type = self.cls_msg_type
self.buf = bytearray(self.datapath.ofproto.OFP_HEADER_SIZE)
def _serialize_header(self):
# buffer length is determined after trailing data is formated.
assert self.version is not None
assert self.msg_type is not None
assert self.buf is not None
assert len(self.buf) >= self.datapath.ofproto.OFP_HEADER_SIZE
self.msg_len = len(self.buf)
if self.xid is None:
self.xid = 0
struct.pack_into(self.datapath.ofproto.OFP_HEADER_PACK_STR,
self.buf, 0,
self.version, self.msg_type, self.msg_len, self.xid)
def _serialize_body(self):
pass
def serialize(self):
self._serialize_pre()
self._serialize_body()
self._serialize_header()
def msg_pack_into(fmt, buf, offset, *args):
if len(buf) < offset:
buf += bytearray(offset - len(buf))
if len(buf) == offset:
buf += struct.pack(fmt, *args)
return
needed_len = offset + struct.calcsize(fmt)
if len(buf) < needed_len:
buf += bytearray(needed_len - len(buf))
struct.pack_into(fmt, buf, offset, *args)
def namedtuple(typename, fields, **kwargs):
class _namedtuple(StringifyMixin,
collections.namedtuple(typename, fields, **kwargs)):
pass
return _namedtuple
def msg_str_attr(msg_, buf, attr_list=None):
if attr_list is None:
attr_list = stringify.obj_attrs(msg_)
for attr in attr_list:
val = getattr(msg_, attr, None)
if val is not None:
buf += ' %s %s' % (attr, val)
return buf