mirror of https://gerrit.osmocom.org/pysim
31.102: Fix EF.Routing_Indicator for odd number of digits
The routing indicator is BCD-encoded but has an arbitrary length of 1, 2, 3 or 4 digits. In order to support the odd lengths of 1 or 3, we must not pad on the byte level, but on the nibble level. This requires a slight extension of the Rpad() Adapter. Change-Id: I6c26dccdd570de7b7a4cd48338068e230340ec7c Fixes: OS#6054
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@ -66,26 +66,29 @@ class InvertAdapter(Adapter):
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class Rpad(Adapter):
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"""
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Encoder appends padding bytes (b'\\xff') up to target size.
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Decoder removes trailing padding bytes.
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Encoder appends padding bytes (b'\\xff') or characters up to target size.
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Decoder removes trailing padding bytes/characters.
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Parameters:
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subcon: Subconstruct as defined by construct library
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pattern: set padding pattern (default: b'\\xff')
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num_per_byte: number of 'elements' per byte. E.g. for hex nibbles: 2
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"""
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def __init__(self, subcon, pattern=b'\xff'):
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def __init__(self, subcon, pattern=b'\xff', num_per_byte=1):
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super().__init__(subcon)
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self.pattern = pattern
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self.num_per_byte = num_per_byte
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def _decode(self, obj, context, path):
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return obj.rstrip(self.pattern)
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def _encode(self, obj, context, path):
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if len(obj) > self.sizeof():
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target_size = self.sizeof() * self.num_per_byte
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if len(obj) > target_size:
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raise SizeofError("Input ({}) exceeds target size ({})".format(
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len(obj), self.sizeof()))
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return obj + self.pattern * (self.sizeof() - len(obj))
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len(obj), target_size))
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return obj + self.pattern * (target_size - len(obj))
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class MultiplyAdapter(Adapter):
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"""
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@ -1089,7 +1089,8 @@ class EF_Routing_Indicator(TransparentEF):
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# responsibility of home network operator but BCD coding shall be used. If a network
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# operator decides to assign less than 4 digits to Routing Indicator, the remaining digits
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# shall be coded as "1111" to fill the 4 digits coding of Routing Indicator
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self._construct = Struct('routing_indicator'/BcdAdapter(Rpad(Bytes(2))), 'rfu'/HexAdapter(Bytes(2)))
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self._construct = Struct('routing_indicator'/Rpad(BcdAdapter(Bytes(2)), 'f', 2),
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'rfu'/HexAdapter(Bytes(2)))
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# TS 31.102 Section 4.4.11.13
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class EF_TN3GPPSNN(TransparentEF):
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