647 lines
21 KiB
Python
647 lines
21 KiB
Python
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# scapy.contrib.description = EtherCat
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# scapy.contrib.status = loads
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"""
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EtherCat automation protocol
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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:author: Thomas Tannhaeuser, hecke@naberius.de
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:license: GPLv2
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This module is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This module is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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:description:
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This module provides Scapy layers for the EtherCat protocol.
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normative references:
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- IEC 61158-3-12 - data link service and topology description
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- IEC 61158-4-12 - protocol specification
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Currently only read/write services as defined in IEC 61158-4-12,
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sec. 5.4 are supported.
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:TODO:
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- Mailbox service (sec. 5.5)
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- Network variable service (sec. 5.6)
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:NOTES:
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- EtherCat frame type defaults to TYPE-12-PDU (0x01) using xxx bytes
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of padding
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- padding for minimum frame size is added automatically
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"""
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import struct
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from scapy.compat import raw
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from scapy.error import log_runtime, Scapy_Exception
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from scapy.fields import BitField, ByteField, LEShortField, FieldListField, \
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LEIntField, FieldLenField, _EnumField, EnumField
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from scapy.layers.l2 import Ether, Dot1Q
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from scapy.modules import six
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from scapy.packet import bind_layers, Packet, Padding
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'''
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EtherCat uses some little endian bitfields without alignment to any common boundaries. # noqa: E501
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See https://github.com/secdev/scapy/pull/569#issuecomment-295419176 for a short explanation # noqa: E501
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why the following field definitions are necessary.
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'''
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class LEBitFieldSequenceException(Scapy_Exception):
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"""
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thrown by EtherCat structure tests
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"""
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pass
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class LEBitField(BitField):
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"""
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a little endian version of the BitField
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"""
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def _check_field_type(self, pkt, index):
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"""
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check if the field addressed by given index relative to this field
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shares type of this field so we can catch a mix of LEBitField
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and BitField/other types
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"""
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my_idx = pkt.fields_desc.index(self)
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try:
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next_field = pkt.fields_desc[my_idx + index]
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if type(next_field) is not LEBitField and \
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next_field.__class__.__base__ is not LEBitField:
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raise LEBitFieldSequenceException('field after field {} must '
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'be of type LEBitField or '
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'derived classes'.format(self.name)) # noqa: E501
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except IndexError:
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# no more fields -> error
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raise LEBitFieldSequenceException('Missing further LEBitField '
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'based fields after field '
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'{} '.format(self.name))
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def addfield(self, pkt, s, val):
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"""
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:param pkt: packet instance the raw string s and field belongs to
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:param s: raw string representing the frame
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:param val: value
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:return: final raw string, tuple (s, bitsdone, data) if in between bit field # noqa: E501
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as we don't know the final size of the full bitfield we need to accumulate the data. # noqa: E501
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if we reach a field that ends at a octet boundary, we build the whole string # noqa: E501
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"""
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if type(s) is tuple and len(s) == 4:
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s, bitsdone, data, _ = s
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self._check_field_type(pkt, -1)
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else:
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# this is the first bit field in the set
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bitsdone = 0
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data = []
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bitsdone += self.size
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data.append((self.size, self.i2m(pkt, val)))
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if bitsdone % 8:
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# somewhere in between bit 0 .. 7 - next field should add more bits... # noqa: E501
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self._check_field_type(pkt, 1)
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return s, bitsdone, data, type(LEBitField)
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else:
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data.reverse()
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octet = 0
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remaining_len = 8
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octets = bytearray()
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for size, val in data:
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while True:
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if size < remaining_len:
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remaining_len = remaining_len - size
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octet |= val << remaining_len
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break
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elif size > remaining_len:
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# take the leading bits and add them to octet
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size -= remaining_len
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octet |= val >> size
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octets = struct.pack('!B', octet) + octets
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octet = 0
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remaining_len = 8
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# delete all consumed bits
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# TODO: do we need to add a check for bitfields > 64 bits to catch overruns here? # noqa: E501
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val &= ((2 ** size) - 1)
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continue
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else:
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# size == remaining len
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octet |= val
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octets = struct.pack('!B', octet) + octets
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octet = 0
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remaining_len = 8
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break
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return s + octets
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def getfield(self, pkt, s):
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"""
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extract data from raw str
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collect all instances belonging to the bit field set.
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if we reach a field that ends at a octet boundary, dissect the whole bit field at once # noqa: E501
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:param pkt: packet instance the field belongs to
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:param s: raw string representing the frame -or- tuple containing raw str, number of bits and array of fields # noqa: E501
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:return: tuple containing raw str, number of bits and array of fields -or- remaining raw str and value of this # noqa: E501
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"""
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if type(s) is tuple and len(s) == 3:
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s, bits_in_set, fields = s
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else:
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bits_in_set = 0
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fields = []
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bits_in_set += self.size
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fields.append(self)
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if bits_in_set % 8:
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# we are in between the bitfield
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return (s, bits_in_set, fields), None
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else:
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cur_val = 0
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cur_val_bit_idx = 0
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this_val = 0
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field_idx = 0
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field = fields[field_idx]
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field_required_bits = field.size
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idx = 0
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s = bytearray(s)
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bf_total_byte_length = bits_in_set // 8
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for octet in s[0:bf_total_byte_length]:
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idx += 1
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octet_bits_left = 8
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while octet_bits_left:
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if field_required_bits == octet_bits_left:
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# whole field fits into remaining bits
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# as this also signals byte-alignment this should exit the inner and outer loop # noqa: E501
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cur_val |= octet << cur_val_bit_idx
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pkt.fields[field.name] = cur_val
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'''
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TODO: check if do_dessect() needs a non-None check for assignment to raw_packet_cache_fields # noqa: E501
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setfieldval() is evil as it sets raw_packet_cache_fields to None - but this attribute # noqa: E501
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is accessed in do_dissect() without checking for None... exception is caught and the # noqa: E501
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user ends up with a layer decoded as raw...
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pkt.setfieldval(field.name, int(bit_str[:field.size], 2)) # noqa: E501
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'''
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octet_bits_left = 0
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this_val = cur_val
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elif field_required_bits < octet_bits_left:
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# pick required bits
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cur_val |= (octet & ((2 ** field_required_bits) - 1)) << cur_val_bit_idx # noqa: E501
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pkt.fields[field.name] = cur_val
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# remove consumed bits
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octet >>= field_required_bits
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octet_bits_left -= field_required_bits
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# and move to the next field
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field_idx += 1
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field = fields[field_idx]
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field_required_bits = field.size
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cur_val_bit_idx = 0
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cur_val = 0
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elif field_required_bits > octet_bits_left:
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# take remaining bits
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cur_val |= octet << cur_val_bit_idx
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cur_val_bit_idx += octet_bits_left
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field_required_bits -= octet_bits_left
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octet_bits_left = 0
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return s[bf_total_byte_length:], this_val
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class LEBitFieldLenField(LEBitField):
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__slots__ = ["length_of", "count_of", "adjust"]
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def __init__(self, name, default, size, length_of=None, count_of=None, adjust=lambda pkt, x: x): # noqa: E501
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LEBitField.__init__(self, name, default, size)
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self.length_of = length_of
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self.count_of = count_of
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self.adjust = adjust
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def i2m(self, pkt, x):
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return (FieldLenField.i2m.__func__ if six.PY2 else FieldLenField.i2m)(self, pkt, x) # noqa: E501
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class LEBitEnumField(LEBitField, _EnumField):
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__slots__ = EnumField.__slots__
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def __init__(self, name, default, size, enum):
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_EnumField.__init__(self, name, default, enum)
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self.rev = size < 0
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self.size = abs(size)
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################################################
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# DLPDU structure definitions (read/write PDUs)
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################################################
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ETHERCAT_TYPE_12_CIRCULATING_FRAME = {
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0x00: 'FRAME-NOT-CIRCULATING',
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0x01: 'FRAME-CIRCULATED-ONCE'
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}
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ETHERCAT_TYPE_12_NEXT_FRAME = {
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0x00: 'LAST-TYPE12-PDU',
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0x01: 'TYPE12-PDU-FOLLOWS'
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}
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class EtherCatType12DLPDU(Packet):
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"""
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Type12 message base class
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"""
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def post_build(self, pkt, pay):
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"""
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set next attr automatically if not set explicitly by user
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:param pkt: raw string containing the current layer
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:param pay: raw string containing the payload
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:return: <new current layer> + payload
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"""
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data_len = len(self.data)
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if data_len > 2047:
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raise ValueError('payload size {} exceeds maximum length {} '
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'of data size.'.format(data_len, 2047))
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if self.next is not None:
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has_next = True if self.next else False
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else:
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if pay:
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has_next = True
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else:
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has_next = False
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if has_next:
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next_flag = bytearray([pkt[7] | 0b10000000])
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else:
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next_flag = bytearray([pkt[7] & 0b01111111])
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return pkt[:7] + next_flag + pkt[8:] + pay
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def guess_payload_class(self, payload):
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try:
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dlpdu_type = payload[0]
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return EtherCat.ETHERCAT_TYPE12_DLPDU_TYPES[dlpdu_type]
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except KeyError:
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log_runtime.error(
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'{}.guess_payload_class() - unknown or invalid '
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'DLPDU type'.format(self.__class__.__name__))
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return Packet.guess_payload_class(self, payload)
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# structure templates lacking leading cmd-attribute
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PHYSICAL_ADDRESSING_DESC = [
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ByteField('idx', 0),
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LEShortField('adp', 0),
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LEShortField('ado', 0),
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LEBitFieldLenField('len', None, 11, count_of='data'),
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LEBitField('_reserved', 0, 3),
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LEBitEnumField('c', 0, 1, ETHERCAT_TYPE_12_CIRCULATING_FRAME),
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LEBitEnumField('next', None, 1, ETHERCAT_TYPE_12_NEXT_FRAME),
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LEShortField('irq', 0),
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FieldListField('data', [], ByteField('', 0x00),
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count_from=lambda pkt: pkt.len),
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LEShortField('wkc', 0)
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]
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BROADCAST_ADDRESSING_DESC = PHYSICAL_ADDRESSING_DESC
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LOGICAL_ADDRESSING_DESC = [
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ByteField('idx', 0),
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LEIntField('adr', 0),
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LEBitFieldLenField('len', None, 11, count_of='data'),
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LEBitField('_reserved', 0, 3),
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LEBitEnumField('c', 0, 1, ETHERCAT_TYPE_12_CIRCULATING_FRAME),
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LEBitEnumField('next', None, 1, ETHERCAT_TYPE_12_NEXT_FRAME),
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LEShortField('irq', 0),
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FieldListField('data', [], ByteField('', 0x00),
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count_from=lambda pkt: pkt.len),
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LEShortField('wkc', 0)
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]
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################
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# read messages
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################
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class EtherCatAPRD(EtherCatType12DLPDU):
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"""
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APRD - Auto Increment Physical Read
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(IEC 61158-5-12, sec. 5.4.1.2 tab. 14 / p. 32)
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"""
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fields_desc = [ByteField('_cmd', 0x01)] + \
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EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
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class EtherCatFPRD(EtherCatType12DLPDU):
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"""
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FPRD - Configured address physical read
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(IEC 61158-5-12, sec. 5.4.1.3 tab. 15 / p. 33)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x04)] + \
|
||
|
|
EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatBRD(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
BRD - Broadcast read
|
||
|
|
(IEC 61158-5-12, sec. 5.4.1.4 tab. 16 / p. 34)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x07)] + \
|
||
|
|
EtherCatType12DLPDU.BROADCAST_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatLRD(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
LRD - Logical read
|
||
|
|
(IEC 61158-5-12, sec. 5.4.1.5 tab. 17 / p. 36)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x0a)] + \
|
||
|
|
EtherCatType12DLPDU.LOGICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
#################
|
||
|
|
# write messages
|
||
|
|
#################
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatAPWR(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
APWR - Auto Increment Physical Write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.2.2 tab. 18 / p. 37)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x02)] + \
|
||
|
|
EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatFPWR(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
FPWR - Configured address physical write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.2.3 tab. 19 / p. 38)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x05)] + \
|
||
|
|
EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatBWR(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
BWR - Broadcast read (IEC 61158-5-12, sec. 5.4.2.4 tab. 20 / p. 39)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x08)] + \
|
||
|
|
EtherCatType12DLPDU.BROADCAST_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatLWR(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
LWR - Logical write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.2.5 tab. 21 / p. 40)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x0b)] + \
|
||
|
|
EtherCatType12DLPDU.LOGICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
######################
|
||
|
|
# read/write messages
|
||
|
|
######################
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatAPRW(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
APRW - Auto Increment Physical Read Write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.3.1 tab. 22 / p. 41)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x03)] + \
|
||
|
|
EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatFPRW(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
FPRW - Configured address physical read write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.3.2 tab. 23 / p. 43)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x06)] + \
|
||
|
|
EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatBRW(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
BRW - Broadcast read write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.3.3 tab. 24 / p. 39)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x09)] + \
|
||
|
|
EtherCatType12DLPDU.BROADCAST_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatLRW(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
LRW - Logical read write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.3.4 tab. 25 / p. 45)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x0c)] + \
|
||
|
|
EtherCatType12DLPDU.LOGICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatARMW(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
ARMW - Auto increment physical read multiple write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.3.5 tab. 26 / p. 46)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x0d)] + \
|
||
|
|
EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCatFRMW(EtherCatType12DLPDU):
|
||
|
|
"""
|
||
|
|
FRMW - Configured address physical read multiple write
|
||
|
|
(IEC 61158-5-12, sec. 5.4.3.6 tab. 27 / p. 47)
|
||
|
|
"""
|
||
|
|
|
||
|
|
fields_desc = [ByteField('_cmd', 0x0e)] + \
|
||
|
|
EtherCatType12DLPDU.PHYSICAL_ADDRESSING_DESC
|
||
|
|
|
||
|
|
|
||
|
|
class EtherCat(Packet):
|
||
|
|
"""
|
||
|
|
Common EtherCat header layer
|
||
|
|
"""
|
||
|
|
ETHER_HEADER_LEN = 14
|
||
|
|
ETHER_FSC_LEN = 4
|
||
|
|
ETHER_FRAME_MIN_LEN = 64
|
||
|
|
ETHERCAT_HEADER_LEN = 2
|
||
|
|
|
||
|
|
FRAME_TYPES = {
|
||
|
|
0x01: 'TYPE-12-PDU',
|
||
|
|
0x04: 'NETWORK-VARIABLES',
|
||
|
|
0x05: 'MAILBOX'
|
||
|
|
}
|
||
|
|
|
||
|
|
fields_desc = [
|
||
|
|
LEBitField('length', 0, 11),
|
||
|
|
LEBitField('_reserved', 0, 1),
|
||
|
|
LEBitField('type', 0, 4),
|
||
|
|
]
|
||
|
|
|
||
|
|
ETHERCAT_TYPE12_DLPDU_TYPES = {
|
||
|
|
0x01: EtherCatAPRD,
|
||
|
|
0x04: EtherCatFPRD,
|
||
|
|
0x07: EtherCatBRD,
|
||
|
|
0x0a: EtherCatLRD,
|
||
|
|
0x02: EtherCatAPWR,
|
||
|
|
0x05: EtherCatFPWR,
|
||
|
|
0x08: EtherCatBWR,
|
||
|
|
0x0b: EtherCatLWR,
|
||
|
|
0x03: EtherCatAPRW,
|
||
|
|
0x06: EtherCatFPRW,
|
||
|
|
0x09: EtherCatBRW,
|
||
|
|
0x0c: EtherCatLRW,
|
||
|
|
0x0d: EtherCatARMW,
|
||
|
|
0x0e: EtherCatFRMW
|
||
|
|
}
|
||
|
|
|
||
|
|
def post_build(self, pkt, pay):
|
||
|
|
"""
|
||
|
|
need to set the length of the whole PDU manually
|
||
|
|
to avoid any bit fiddling use a dummy class to build the layer content
|
||
|
|
|
||
|
|
also add padding if frame is < 64 bytes
|
||
|
|
|
||
|
|
Note: padding only handles Ether/n*Dot1Q/EtherCat
|
||
|
|
(no special mumbo jumbo)
|
||
|
|
|
||
|
|
:param pkt: raw string containing the current layer
|
||
|
|
:param pay: raw string containing the payload
|
||
|
|
:return: <new current layer> + payload
|
||
|
|
"""
|
||
|
|
|
||
|
|
class _EtherCatLengthCalc(Packet):
|
||
|
|
"""
|
||
|
|
dummy class used to generate str representation easily
|
||
|
|
"""
|
||
|
|
fields_desc = [
|
||
|
|
LEBitField('length', None, 11),
|
||
|
|
LEBitField('_reserved', 0, 1),
|
||
|
|
LEBitField('type', 0, 4),
|
||
|
|
]
|
||
|
|
|
||
|
|
payload_len = len(pay)
|
||
|
|
|
||
|
|
# length field is 11 bit
|
||
|
|
if payload_len > 2047:
|
||
|
|
raise ValueError('payload size {} exceeds maximum length {} '
|
||
|
|
'of EtherCat message.'.format(payload_len, 2047))
|
||
|
|
|
||
|
|
self.length = payload_len
|
||
|
|
|
||
|
|
vlan_headers_total_size = 0
|
||
|
|
upper_layer = self.underlayer
|
||
|
|
|
||
|
|
# add size occupied by VLAN tags
|
||
|
|
while upper_layer and isinstance(upper_layer, Dot1Q):
|
||
|
|
vlan_headers_total_size += 4
|
||
|
|
upper_layer = upper_layer.underlayer
|
||
|
|
|
||
|
|
if not isinstance(upper_layer, Ether):
|
||
|
|
raise Exception('missing Ether layer')
|
||
|
|
|
||
|
|
pad_len = EtherCat.ETHER_FRAME_MIN_LEN - (EtherCat.ETHER_HEADER_LEN +
|
||
|
|
vlan_headers_total_size +
|
||
|
|
EtherCat.ETHERCAT_HEADER_LEN + # noqa: E501
|
||
|
|
payload_len +
|
||
|
|
EtherCat.ETHER_FSC_LEN)
|
||
|
|
|
||
|
|
if pad_len > 0:
|
||
|
|
pad = Padding()
|
||
|
|
pad.load = b'\x00' * pad_len
|
||
|
|
|
||
|
|
return raw(_EtherCatLengthCalc(length=self.length,
|
||
|
|
type=self.type)) + pay + raw(pad)
|
||
|
|
return raw(_EtherCatLengthCalc(length=self.length,
|
||
|
|
type=self.type)) + pay
|
||
|
|
|
||
|
|
def guess_payload_class(self, payload):
|
||
|
|
try:
|
||
|
|
dlpdu_type = payload[0]
|
||
|
|
return EtherCat.ETHERCAT_TYPE12_DLPDU_TYPES[dlpdu_type]
|
||
|
|
except KeyError:
|
||
|
|
log_runtime.error(
|
||
|
|
'{}.guess_payload_class() - unknown or invalid '
|
||
|
|
'DLPDU type'.format(self.__class__.__name__))
|
||
|
|
return Packet.guess_payload_class(self, payload)
|
||
|
|
|
||
|
|
|
||
|
|
bind_layers(Ether, EtherCat, type=0x88a4)
|
||
|
|
bind_layers(Dot1Q, EtherCat, type=0x88a4)
|
||
|
|
|
||
|
|
# bindings for DLPDUs
|
||
|
|
|
||
|
|
bind_layers(EtherCat, EtherCatAPRD, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatFPRD, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatBRD, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatLRD, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatAPWR, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatFPWR, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatBWR, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatLWR, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatAPRW, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatFPRW, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatBRW, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatLRW, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatARMW, type=0x01)
|
||
|
|
bind_layers(EtherCat, EtherCatFRMW, type=0x01)
|