Rich Lane | 15cbe84 | 2013-04-26 16:04:11 -0700 | [diff] [blame] | 1 | :: # Copyright 2013, Big Switch Networks, Inc. |
| 2 | :: # |
| 3 | :: # LoxiGen is licensed under the Eclipse Public License, version 1.0 (EPL), with |
| 4 | :: # the following special exception: |
| 5 | :: # |
| 6 | :: # LOXI Exception |
| 7 | :: # |
| 8 | :: # As a special exception to the terms of the EPL, you may distribute libraries |
| 9 | :: # generated by LoxiGen (LoxiGen Libraries) under the terms of your choice, provided |
| 10 | :: # that copyright and licensing notices generated by LoxiGen are not altered or removed |
| 11 | :: # from the LoxiGen Libraries and the notice provided below is (i) included in |
| 12 | :: # the LoxiGen Libraries, if distributed in source code form and (ii) included in any |
| 13 | :: # documentation for the LoxiGen Libraries, if distributed in binary form. |
| 14 | :: # |
| 15 | :: # Notice: "Copyright 2013, Big Switch Networks, Inc. This library was generated by the LoxiGen Compiler." |
| 16 | :: # |
| 17 | :: # You may not use this file except in compliance with the EPL or LOXI Exception. You may obtain |
| 18 | :: # a copy of the EPL at: |
| 19 | :: # |
| 20 | :: # http://www.eclipse.org/legal/epl-v10.html |
| 21 | :: # |
| 22 | :: # Unless required by applicable law or agreed to in writing, software |
| 23 | :: # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 24 | :: # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| 25 | :: # EPL for the specific language governing permissions and limitations |
| 26 | :: # under the EPL. |
| 27 | :: |
| 28 | :: include('_copyright.py') |
| 29 | """ |
| 30 | Utility functions independent of the protocol version |
| 31 | """ |
| 32 | |
| 33 | :: include('_autogen.py') |
| 34 | |
| 35 | import loxi |
| 36 | import struct |
| 37 | |
Rich Lane | 57026dc | 2013-05-01 10:13:16 -0700 | [diff] [blame] | 38 | def unpack_list(reader, deserializer): |
Rich Lane | 15cbe84 | 2013-04-26 16:04:11 -0700 | [diff] [blame] | 39 | """ |
Rich Lane | 57026dc | 2013-05-01 10:13:16 -0700 | [diff] [blame] | 40 | The deserializer function should take an OFReader and return the new object. |
Rich Lane | 15cbe84 | 2013-04-26 16:04:11 -0700 | [diff] [blame] | 41 | """ |
| 42 | entries = [] |
Rich Lane | 57026dc | 2013-05-01 10:13:16 -0700 | [diff] [blame] | 43 | while not reader.is_empty(): |
| 44 | entries.append(deserializer(reader)) |
Rich Lane | 15cbe84 | 2013-04-26 16:04:11 -0700 | [diff] [blame] | 45 | return entries |
Rich Lane | 1de06ab | 2013-04-26 16:58:37 -0700 | [diff] [blame] | 46 | |
Rich Lane | 57026dc | 2013-05-01 10:13:16 -0700 | [diff] [blame] | 47 | def unpack_list_lv16(reader, deserializer): |
| 48 | """ |
| 49 | The deserializer function should take an OFReader and return the new object. |
| 50 | """ |
| 51 | def wrapper(reader): |
| 52 | length, = reader.peek('!H') |
| 53 | return deserializer(reader.slice(length)) |
| 54 | return unpack_list(reader, wrapper) |
| 55 | |
| 56 | def unpack_list_tlv16(reader, deserializer): |
| 57 | """ |
| 58 | The deserializer function should take an OFReader and an integer type |
| 59 | and return the new object. |
| 60 | """ |
| 61 | def wrapper(reader): |
| 62 | typ, length, = reader.peek('!HH') |
| 63 | return deserializer(reader.slice(length), typ) |
| 64 | return unpack_list(reader, wrapper) |
| 65 | |
Rich Lane | 1de06ab | 2013-04-26 16:58:37 -0700 | [diff] [blame] | 66 | class OFReader(object): |
| 67 | """ |
| 68 | Cursor over a read-only buffer |
| 69 | |
| 70 | OpenFlow messages are best thought of as a sequence of elements of |
| 71 | variable size, rather than a C-style struct with fixed offsets and |
| 72 | known field lengths. This class supports efficiently reading |
| 73 | fields sequentially and is intended to be used recursively by the |
| 74 | parsers of child objects which will implicitly update the offset. |
| 75 | """ |
| 76 | def __init__(self, buf): |
| 77 | self.buf = buf |
| 78 | self.offset = 0 |
| 79 | |
| 80 | def read(self, fmt): |
| 81 | st = struct.Struct(fmt) |
| 82 | if self.offset + st.size > len(self.buf): |
| 83 | raise loxi.ProtocolError("Buffer too short") |
| 84 | result = st.unpack_from(self.buf, self.offset) |
| 85 | self.offset += st.size |
| 86 | return result |
| 87 | |
| 88 | def read_all(self): |
| 89 | buf = buffer(self.buf, self.offset) |
| 90 | self.offset += len(buf) |
| 91 | return str(buf) |
| 92 | |
| 93 | def peek(self, fmt): |
| 94 | st = struct.Struct(fmt) |
| 95 | if self.offset + st.size > len(self.buf): |
| 96 | raise loxi.ProtocolError("Buffer too short") |
| 97 | result = st.unpack_from(self.buf, self.offset) |
| 98 | return result |
| 99 | |
| 100 | def skip(self, length): |
| 101 | if self.offset + length > len(self.buf): |
| 102 | raise loxi.ProtocolError("Buffer too short") |
| 103 | self.offset += length |
| 104 | |
| 105 | def is_empty(self): |
| 106 | return self.offset == len(self.buf) |
| 107 | |
| 108 | # Used when parsing variable length objects which have external length |
| 109 | # fields (e.g. the actions list in an OF 1.0 packet-out message). |
| 110 | def slice(self, length): |
| 111 | if self.offset + length > len(self.buf): |
| 112 | raise loxi.ProtocolError("Buffer too short") |
| 113 | buf = OFReader(buffer(self.buf, self.offset, length)) |
| 114 | self.offset += length |
| 115 | return buf |