| 1 | from .value import Value |
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| 2 | import sys |
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| 3 | import struct |
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| 4 | import logging |
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| 5 | |
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| 6 | # initialize logger |
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| 7 | logger = logging.getLogger(__name__) |
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| 8 | |
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| 9 | class Attribute(object): |
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| 10 | """In addition to what the RFC reports, an attribute has an |
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| 11 | 'attribute tag', which specifies what type of attribute it is. It |
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| 12 | is 1 bytes long, and comes before the list of values. |
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| 13 | |
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| 14 | From RFC 2565: |
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| 15 | |
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| 16 | Each attribute consists of: |
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| 17 | ----------------------------------------------- |
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| 18 | | value-tag | 1 byte |
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| 19 | ----------------------------------------------- |
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| 20 | | name-length (value is u) | 2 bytes |
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| 21 | ----------------------------------------------- |
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| 22 | | name | u bytes |
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| 23 | ----------------------------------------------- |
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| 24 | | value-length (value is v) | 2 bytes |
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| 25 | ----------------------------------------------- |
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| 26 | | value | v bytes |
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| 27 | ----------------------------------------------- |
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| 28 | |
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| 29 | An additional value consists of: |
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| 30 | ----------------------------------------------------------- |
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| 31 | | value-tag | 1 byte | |
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| 32 | ----------------------------------------------- | |
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| 33 | | name-length (value is 0x0000) | 2 bytes | |
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| 34 | ----------------------------------------------- |-0 or more |
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| 35 | | value-length (value is w) | 2 bytes | |
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| 36 | ----------------------------------------------- | |
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| 37 | | value | w bytes | |
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| 38 | ----------------------------------------------------------- |
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| 39 | |
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| 40 | """ |
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| 41 | |
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| 42 | def __init__(self, name=None, values=None): |
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| 43 | """Initialize an Attribute. This function can be called in |
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| 44 | three different ways: |
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| 45 | |
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| 46 | Attribute() -- creates an empty Attribute |
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| 47 | |
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| 48 | Attribute(name) -- creates an empty Attribute with a name |
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| 49 | |
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| 50 | Attribute(name, values) -- creates an Attribute |
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| 51 | initialized with a name and list of values |
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| 52 | |
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| 53 | Arguments: |
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| 54 | |
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| 55 | name -- the name of the attribute |
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| 56 | |
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| 57 | values -- a list of Values. May not be empty. |
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| 58 | |
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| 59 | """ |
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| 60 | |
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| 61 | if name is not None and not isinstance(name, str): |
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| 62 | raise ValueError("attribute name must be a string") |
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| 63 | if values is None: |
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| 64 | values = [] |
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| 65 | for value in values: |
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| 66 | if not isinstance(value, Value): |
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| 67 | raise ValueError("value %s must be of type Value" % (value,)) |
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| 68 | |
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| 69 | self.name = name |
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| 70 | self.values = values |
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| 71 | |
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| 72 | def __cmp__(self, other): |
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| 73 | eq = self.name == other.name |
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| 74 | for v1, v2 in zip(self.values, other.values): |
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| 75 | eq = eq and (v1 == v2) |
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| 76 | return 0 if eq else 1 |
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| 77 | |
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| 78 | @property |
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| 79 | def packed_value(self): |
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| 80 | """Packs the attribute data into binary data. |
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| 81 | |
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| 82 | """ |
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| 83 | |
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| 84 | if self.name is None: |
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| 85 | raise ValueError, "cannot pack unnamed attribute" |
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| 86 | if len(self.values) == 0: |
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| 87 | raise ValueError, "cannot pack empty attribute" |
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| 88 | |
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| 89 | # get the binary data for all the values |
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| 90 | values = [] |
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| 91 | for v, i in zip(self.values, xrange(len(self.values))): |
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| 92 | |
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| 93 | # get the name length (0 for everything but the first |
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| 94 | # value) |
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| 95 | name_length = len(self.name) if i == 0 else 0 |
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| 96 | |
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| 97 | logger.debug("dumping name : %s" % self.name) |
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| 98 | logger.debug("dumping name_length : %i" % name_length) |
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| 99 | logger.debug("value tag : 0x%x" % v.tag) |
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| 100 | |
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| 101 | # get the binary value |
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| 102 | value_bin = v.packed_value |
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| 103 | # get the value length |
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| 104 | value_length = len(value_bin) |
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| 105 | |
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| 106 | logger.debug("dumping value : %s" % v.value) |
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| 107 | logger.debug("dumping value_length : %i" % value_length) |
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| 108 | |
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| 109 | # the value tag in binary |
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| 110 | tag_bin = struct.pack('>b', v.tag) |
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| 111 | # the name length in binary |
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| 112 | name_length_bin = struct.pack('>h', name_length) |
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| 113 | # the name in binary |
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| 114 | name_bin = self.name |
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| 115 | # the value length in binary |
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| 116 | value_length_bin = struct.pack('>h', value_length) |
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| 117 | |
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| 118 | # add the binary value to the list of values |
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| 119 | vlist = [tag_bin, name_length_bin, value_length_bin, value_bin] |
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| 120 | if i == 0: |
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| 121 | vlist.insert(2, name_bin) |
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| 122 | values.append(''.join(vlist)) |
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| 123 | |
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| 124 | # concatenate everything together and return it along with the |
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| 125 | # total length of the attribute |
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| 126 | return ''.join(values) |
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| 127 | |
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| 128 | @property |
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| 129 | def packed_value_size(self): |
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| 130 | """Gets the total size of the attribute. |
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| 131 | |
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| 132 | """ |
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| 133 | |
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| 134 | return len(self.packed_value) |
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| 135 | |
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| 136 | total_size = packed_value_size |
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| 137 | |
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| 138 | def __str__(self): |
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| 139 | if len(self.values) > 0: |
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| 140 | values = [str(v) for v in self.values] |
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| 141 | else: |
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| 142 | values = "None" |
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| 143 | |
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| 144 | if self.name is None: |
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| 145 | name = "None" |
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| 146 | else: |
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| 147 | name = self.name |
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| 148 | |
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| 149 | return "%s: %s" % (name, str(values)) |
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| 150 | |
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| 151 | def __repr__(self): |
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| 152 | return '<IPPAttribute (%r, %r)>' % (self.name, self.values) |
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