SMS-DELIVER from number decoding error

[9dogs]

Hey, I've encountered strange bug while decoding some pdu's. I got EncodingError exception on some messages while the others are decoding normally. It seems that a problem is in a function nibble2octet:

def nibble2octet(o):
    if o % 2:
        return o / 2 + 1
    else:
        return o / 2

In Python 3 this function can produce float values. The value is used later in unpackSeptets and comparison with int breaks desired behavior. If it is simple python2->python3 migration issue, it can be fixed simply by return int(o / 2) + 1. Can somebody confirm that fix doesn't break anything else?

[tomchy]

Back in the faucamp/python-gsmmodem repository instead of nibble2octet(o) there were two pieces of code doing this operation:

addressLen = int(math.ceil(addressLen / 2.0))

and:

if addressLen % 2:
    addressLen = int(addressLen / 2) + 1
else:
    addressLen = int(addressLen / 2)

There are no more occurrences of nibble2octet, so I think that confirms that this fix doesn't break anything else 🙂

[9dogs]

Thank you! I'm making pull request then.

[lcnittl]

Just a question: Shouldn't addressLen = int((addressLen + 1) / 2) give the same values, just without the need of an if statement or a function from math?

[babca]

The faucamp@df20a9a fix from 2014 was originally part of the codebase until I merged @paolo-losi branch.

The nibble2octet() function was introduced by paolo-losi@0076b9d to fix something. I think he wanted to use the same piece of code on both places and he forgot to use int() in his new function.

[babca]

quick test, all three blocks give the same values:

0
1
1
2
2
3
3

import math

def testblock1(addressLen):
	if addressLen % 2:
	    addressLen = int(addressLen / 2) + 1
	else:
	    addressLen = int(addressLen / 2)
	print (addressLen)

testblock1(0)
testblock1(1)
testblock1(2)
testblock1(3)
testblock1(4)
testblock1(5)
testblock1(6)

def testblock2(addressLen):
	addressLen = int(math.ceil(addressLen / 2.0))
	print (addressLen)

testblock2(0)
testblock2(1)
testblock2(2)
testblock2(3)
testblock2(4)
testblock2(5)
testblock2(6)

def testblock3(addressLen):
	addressLen = int((addressLen + 1) / 2)
	print (addressLen)

testblock3(0)
testblock3(1)
testblock3(2)
testblock3(3)
testblock3(4)
testblock3(5)
testblock3(6)

[babca]

I suggest to change nibble2octet() function to:

def nibble2octet(addressLen):
    return int((addressLen + 1) / 2)