also, prefix a private method with _.
Signed-off-by: YAMAMOTO Takashi <[email protected]>
---
ryu/lib/packet/packet.py | 39 +++++++++++++++++++++++++++++++++++++--
ryu/lib/packet/packet_base.py | 31 +++++++++++++++++++++++++++++++
2 files changed, 68 insertions(+), 2 deletions(-)
diff --git a/ryu/lib/packet/packet.py b/ryu/lib/packet/packet.py
index da9c412..9533266 100644
--- a/ryu/lib/packet/packet.py
+++ b/ryu/lib/packet/packet.py
@@ -18,7 +18,16 @@ from . import ethernet
class Packet(object):
+ """A packet decoder/encoder class.
+
+ An instance is used to either decode or encode a single packet.
+ """
+
def __init__(self, data=None):
+ """*data* is a bytearray to describe a raw datagram to decode.
+ *data* should be omitted when encoding a packet.
+ """
+
super(Packet, self).__init__()
self.data = data
self.protocols = []
@@ -26,9 +35,9 @@ class Packet(object):
self.parsed_bytes = 0
if self.data:
# Do we need to handle non ethernet?
- self.parser(ethernet.ethernet)
+ self._parser(ethernet.ethernet)
- def parser(self, cls):
+ def _parser(self, cls):
while cls:
proto, cls = cls.parser(self.data[self.parsed_bytes:])
if proto:
@@ -39,6 +48,11 @@ class Packet(object):
self.protocols.append(self.data[self.parsed_bytes:])
def serialize(self):
+ """Encode a packet and store the resulted bytearray in self.data.
+
+ This method is legal only when encoding a packet.
+ """
+
self.data = bytearray()
r = self.protocols[::-1]
for i, p in enumerate(r):
@@ -53,9 +67,21 @@ class Packet(object):
self.data = data + self.data
def add_protocol(self, proto):
+ """Register a protocol *proto* for this packet.
+
+ This method is legal only when encoding a packet.
+
+ When encoding a packet, register a protocol (ethernet, ipv4, ...)
+ header to add to this packet.
+ Protocol headers should be registered in on-wire order before calling
+ self.serialize.
+ """
+
self.protocols.append(proto)
def next(self):
+ """See __iter__."""
+
try:
p = self.protocols[self.protocol_idx]
except:
@@ -66,4 +92,13 @@ class Packet(object):
return p
def __iter__(self):
+ """Iterate protocol (ethernet, ipv4, ...) headers and the payload.
+
+ This method is legal only when decoding a packet.
+
+ Protocol headers are instances of subclass of packet_base.PacketBase.
+ The payload is a bytearray.
+ They are iterated in on-wire order.
+ """
+
return self
diff --git a/ryu/lib/packet/packet_base.py b/ryu/lib/packet/packet_base.py
index aa38eb0..46feb11 100644
--- a/ryu/lib/packet/packet_base.py
+++ b/ryu/lib/packet/packet_base.py
@@ -15,14 +15,23 @@
class PacketBase(object):
+ """A base class for a protocol (ethernet, ipv4, ...) header."""
_TYPES = {}
@classmethod
def get_packet_type(cls, type_):
+ """Per-protocol dict-like get method.
+
+ Provided for convenience of protocol implementers.
+ Internal use only."""
return cls._TYPES.get(type_)
@classmethod
def register_packet_type(cls, cls_, type_):
+ """Per-protocol dict-like set method.
+
+ Provided for convenience of protocol implementers.
+ Internal use only."""
cls._TYPES[type_] = cls_
def __init__(self):
@@ -32,7 +41,29 @@ class PacketBase(object):
@classmethod
def parser(cls, buf):
+ """Decode a protocol header.
+
+ This method is used only when decoding a packet.
+
+ Decode a protocol header at offset 0 in bytearray *buf*.
+ Returns the rest of the packet and the decoded header, which is
+ instance of packet_base.PacketBase subclass.
+ """
pass
def serialize(self, payload, prev):
+ """Encode a protocol header.
+
+ This method is used only when encoding a packet.
+
+ Encode a protocol header.
+ Returns a bytearray which contains the header.
+
+ *payload* is the rest of the packet which will immediately follow
+ this header.
+
+ *prev* is a packet_base.PacketBase subclass for the outer protocol
+ header. *prev* is None if the current header is the outer-most.
+ For example, *prev* is ipv4 or ipv6 for tcp.serialize.
+ """
pass
--
1.8.0.1
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