Signed-off-by: ISHIDA Wataru <[email protected]>
---
ryu/lib/packet/bgp.py | 52 ++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 47 insertions(+), 5 deletions(-)
diff --git a/ryu/lib/packet/bgp.py b/ryu/lib/packet/bgp.py
index b91ece7..5526ab6 100644
--- a/ryu/lib/packet/bgp.py
+++ b/ryu/lib/packet/bgp.py
@@ -1325,6 +1325,15 @@ class _BGPPathAttributeAsPathCommon(_PathAttribute):
_AS_PACK_STR = None
_ATTR_FLAGS = BGP_ATTR_FLAG_TRANSITIVE
+ def __init__(self, value, as_pack_str=None, flags=0, type_=None,
+ length=None):
+ super(_BGPPathAttributeAsPathCommon, self).__init__(value=value,
+ flags=flags,
+ type_=type_,
+ length=length)
+ if as_pack_str:
+ self._AS_PACK_STR = as_pack_str
+
@property
def path_seg_list(self):
return copy.deepcopy(self.value)
@@ -1361,17 +1370,44 @@ class _BGPPathAttributeAsPathCommon(_PathAttribute):
return False
@classmethod
+ def _is_valid_16bit_as_path(cls, buf):
+
+ two_byte_as_size = struct.calcsize('!H')
+
+ while buf:
+ (type_, num_as) = struct.unpack_from(cls._SEG_HDR_PACK_STR,
+ buffer(buf))
+
+ if type_ is not cls._AS_SET and type_ is not cls._AS_SEQUENCE:
+ return False
+
+ buf = buf[struct.calcsize(cls._SEG_HDR_PACK_STR):]
+
+ if len(buf) < num_as * two_byte_as_size:
+ return False
+
+ buf = buf[num_as * two_byte_as_size:]
+
+ return True
+
+ @classmethod
def parse_value(cls, buf):
result = []
+
+ if cls._is_valid_16bit_as_path(buf):
+ as_pack_str = '!H'
+ else:
+ as_pack_str = '!I'
+
while buf:
(type_, num_as) = struct.unpack_from(cls._SEG_HDR_PACK_STR,
buffer(buf))
buf = buf[struct.calcsize(cls._SEG_HDR_PACK_STR):]
l = []
for i in xrange(0, num_as):
- (as_number,) = struct.unpack_from(cls._AS_PACK_STR,
+ (as_number,) = struct.unpack_from(as_pack_str,
buffer(buf))
- buf = buf[struct.calcsize(cls._AS_PACK_STR):]
+ buf = buf[struct.calcsize(as_pack_str):]
l.append(as_number)
if type_ == cls._AS_SET:
result.append(set(l))
@@ -1380,7 +1416,8 @@ class _BGPPathAttributeAsPathCommon(_PathAttribute):
else:
assert(0) # protocol error
return {
- 'value': result
+ 'value': result,
+ 'as_pack_str': as_pack_str,
}
def serialize_value(self):
@@ -1405,14 +1442,15 @@ class _BGPPathAttributeAsPathCommon(_PathAttribute):
@_PathAttribute.register_type(BGP_ATTR_TYPE_AS_PATH)
class BGPPathAttributeAsPath(_BGPPathAttributeAsPathCommon):
- # XXX currently this implementation assumes 16 bit AS numbers.
- # depends on negotiated capability, AS numbers can be 32 bit.
+ # XXX depends on negotiated capability, AS numbers can be 32 bit.
# while wireshark seems to attempt auto-detect, it seems that
# there's no way to detect it reliably. for example, the
# following byte sequence can be interpreted in two ways.
# 01 02 99 88 77 66 02 01 55 44
# AS_SET num=2 9988 7766 AS_SEQUENCE num=1 5544
# AS_SET num=2 99887766 02015544
+ # we first check whether AS path can be parsed in 16bit format and if
+ # it fails, we try to parse as 32bit
_AS_PACK_STR = '!H'
@@ -1420,6 +1458,10 @@ class
BGPPathAttributeAsPath(_BGPPathAttributeAsPathCommon):
class BGPPathAttributeAs4Path(_BGPPathAttributeAsPathCommon):
_AS_PACK_STR = '!I'
+ @classmethod
+ def _is_valid_16bit_as_path(cls, buf):
+ return False
+
@_PathAttribute.register_type(BGP_ATTR_TYPE_NEXT_HOP)
class BGPPathAttributeNextHop(_PathAttribute):
--
1.7.10.4
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