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Bug #4052

Test uncompressed bitmaps without length

Added by lynxis 18 days ago. Updated 8 days ago.

Status:
In Progress
Priority:
Urgent
Assignee:
Target version:
-
Start date:
06/07/2019
Due date:
% Done:

20%

Spec Reference:
44.060

Description

Check and test uncompressed bitmaps without length.


Related issues

Related to OsmoPCU - Bug #3728: Problem using compressed ACK/NACK bitmaps or uncompressed bitmaps without lengthIn Progress12/13/2018

History

#1 Updated by lynxis 18 days ago

  • Related to Bug #3728: Problem using compressed ACK/NACK bitmaps or uncompressed bitmaps without length added

#2 Updated by lynxis 18 days ago

  • Assignee set to lynxis

#3 Updated by lynxis 18 days ago

  • Priority changed from Normal to Urgent

#4 Updated by lynxis 9 days ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 20

There is at least one corner cases, which I'ven't found in the 44.060: What happens when an EGPRS ACK/NACK does not have a Length field, but the uncompressed RBB is less the remaining rest_bits? This was possible, when less than 8 bits were remaining, so only happens when having huge packet loss.

... This is defined as spec compliant. Out of window bits should be ignored.

I've implemented a fix for this in my branch lynxis/gprs-ack-nack https://gerrit.osmocom.org/plugins/gitiles/osmo-pcu/+/lynxis/gprs-ack-nack
I will push this patch to gerrit and write test cases for the encoding.

However I want also validate the encoding of the URBB is correct at all.

#5 Updated by lynxis 9 days ago

  • Spec Reference set to 44.060

#6 Updated by lynxis 8 days ago

lynxis wrote:

There is at least one corner cases, which I'ven't found in the 44.060: What happens when an EGPRS ACK/NACK does not have a Length field, but the uncompressed RBB is less the remaining rest_bits? This was possible, when less than 8 bits were remaining, so only happens when having huge packet loss.

... This is defined as spec compliant. Out of window bits should be ignored.

But those bits are still within the window. They won't be ignored. And bits which represent V(R) or higher must be set to 0 (44.060 9.1.10).

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