PDU creates invalid messages when > allowed length

[vai-brma]

The pdu.py splits long messages up depending on the type of string (GSM-7, UCS2,8-bit) But the calculated lengths are wrong and cause modem errors.

attached is a fixed version that works with Multitech MTD-H5 pdu.py.txt

[tomchy]

Hi! could you test if this issue occurs inside following updated fork ? It has several updates and fixes, including long PDUs :slightly_smiling_face:.

[vai-brma]

chunks calculation in divideTextUcs2 should be:

fullChunksCount = int((len(plainText) -1) / MAX_MULTIPART_MESSAGE_LENGTH[0x08])

From: tomchy [mailto:notifications@github.com] Sent: March-07-17 2:04 PM To: faucamp/python-gsmmodem python-gsmmodem@noreply.github.com Cc: Matthews Brian BRMA Brian.Matthews@vaisala.com; Author author@noreply.github.com Subject: Re: [faucamp/python-gsmmodem] PDU creates invalid messages when > allowed length (#81)

Hi! could you test if this issue occurs inside following updated forkhttps://github.com/babca/python-gsmmodem ? It has several updates and fixes, including long PDUs 🙂.

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[tomchy]

Could you explain that/provide an example?

Current implementation passes following unit tests (last test inside test_pdu.py):

    def test_encode_Ucs2_divideSMS(self):
        """ Tests whether text will be devided into a correct number of chunks while using UCS-2 alphabet"""
        text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060"
        self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 1)
        text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 1234567"
        self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 1)
        text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 12345678"
        self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 2)
        text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 123456["
        self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 1)
        text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 1234567["
        self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 2)
        text = "12345-010,12345-020,12345-030,12345-040,12345-050,12345-060,123456 12345-010,12345-020,12345-030,12345-040,12345-050,12345-060,1234567"
        self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 2)

[vai-brma]

Hi,

 I think it is OK as is.

 if a ucs-2 buffer is exactly 134 bytes long, your calc results in 2 fullChunks and no remainder, whereas my pedantically correct way results in 1 fullChunk and 67 remainder.

Either way it works.

I will try your code tomorrow. It looks OK to me, as it handles the shortened buffer size it needs to  once it is chunked.

Brian

From: tomchy [mailto:notifications@github.com] Sent: March-07-17 4:23 PM To: faucamp/python-gsmmodem python-gsmmodem@noreply.github.com Cc: Matthews Brian BRMA Brian.Matthews@vaisala.com; Author author@noreply.github.com Subject: Re: [faucamp/python-gsmmodem] PDU creates invalid messages when > allowed length (#81)

Could you explain that/provide an example?

Current implementation passes following unit tests (last test inside test_pdu.py):

def test_encode_Ucs2_divideSMS(self):

    """ Tests whether text will be devided into a correct number of chunks while using UCS-2 alphabet"""

    text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060"

    self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 1)

    text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 1234567"

    self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 1)

    text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 12345678"

    self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 2)

    text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 123456["

    self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 1)

    text = "12345-010 12345-020 12345-030 12345-040 12345-050 12345-060 1234567["

    self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 2)

    text = "12345-010,12345-020,12345-030,12345-040,12345-050,12345-060,123456 12345-010,12345-020,12345-030,12345-040,12345-050,12345-060,1234567"

    self.assertEqual(len(gsmmodem.pdu.divideTextUcs2(text)), 2)

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