1 | from .attribute import Attribute |
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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 AttributeGroup(object): |
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10 | """An AttributeGroup consists of an attribute-group-tag, followed |
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11 | by a sequence of Attributes. According to RFC 2565, 'Within an |
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12 | attribute-sequence, if two attributes have the same name, the |
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13 | first occurrence MUST be ignored.', so we can effectively treat |
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14 | this as an ordered dictionary. |
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15 | |
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16 | """ |
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17 | |
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18 | def __init__(self, tag=None, attributes=[]): |
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19 | """Initialize an AttributeGroup. An AttributeGroup can be |
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20 | initialized in three ways: |
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21 | |
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22 | AttributeGroup() |
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23 | AttributeGroup(tag) |
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24 | AttributeGroup(tag, attributes) |
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25 | |
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26 | Arguments: |
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27 | |
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28 | tag -- a signed char, holds the tag of the |
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29 | attribute group |
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30 | |
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31 | attributes -- a list of attributes |
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32 | |
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33 | """ |
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34 | |
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35 | if tag is not None and not isinstance(tag, int): |
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36 | raise ValueError("tag must be a character") |
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37 | |
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38 | self.tag = tag |
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39 | self.attributes = [] |
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40 | self.extend(attributes) |
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41 | |
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42 | def __cmp__(self, other): |
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43 | eq = self.tag == other.tag |
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44 | for a1, a2 in zip(self.attributes, other.attributes): |
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45 | eq = eq and (a1 == a2) |
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46 | return 0 if eq else 1 |
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47 | |
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48 | def __getitem__(self, name): |
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49 | """Returns a list of attributes which have name 'name'. |
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50 | |
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51 | """ |
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52 | |
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53 | attribute = filter(lambda x: x.name == name, self.attributes) |
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54 | if attribute: |
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55 | return attribute[0] |
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56 | else: |
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57 | raise KeyError("Attribute %r not found" % name) |
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58 | |
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59 | def __contains__(self, name): |
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60 | return len(filter(lambda x: x.name == name, self.attributes)) |
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61 | |
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62 | def __iter__(self): |
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63 | return (a.name for a in self.attributes) |
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64 | |
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65 | iterkeys = __iter__ |
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66 | |
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67 | def __setitem__(self, name, attribute): |
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68 | """Sets an attribute in the attribute group. Note that the key |
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69 | is ignored and the attribute is queried for its name. |
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70 | |
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71 | """ |
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72 | |
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73 | return self.append(attribute) |
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74 | |
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75 | def __delitem__(self, name): |
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76 | self.attributes = filter(lambda x: x.name != name, |
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77 | self.attributes) |
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78 | |
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79 | def append(self, attribute): |
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80 | return self.extend([attribute]) |
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81 | |
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82 | def extend(self, attributes): |
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83 | """Sets the attributes for the attribute group. |
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84 | |
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85 | """ |
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86 | |
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87 | for a in attributes: |
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88 | if not isinstance(a, Attribute): |
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89 | raise ValueError("attribute must be of type Attribute") |
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90 | |
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91 | for a in attributes: |
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92 | # XXX: Instead of replacing the attribute, do we want to |
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93 | # append the value to the attribute here? |
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94 | del self[a.name] |
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95 | self.attributes.append(a) |
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96 | |
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97 | @property |
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98 | def packed_value(self): |
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99 | """Convert the AttributeGroup to binary. |
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100 | |
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101 | """ |
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102 | |
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103 | # convert the tag to binary |
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104 | tag = struct.pack('>b', self.tag) |
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105 | |
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106 | # convert each of the attributes to binary |
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107 | attributes = [a.packed_value for a in self.attributes] |
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108 | |
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109 | # concatenate everything and return |
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110 | return tag + ''.join(attributes) |
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111 | |
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112 | def __repr__(self): |
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113 | return '<IPPAttributeGroup (%r, %r)>' % (self.tag, self.attributes) |
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