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Osmocom Packet control Unit (PCU): Network-side GPRS (RLC/MAC); BTS- or BSC-colocated https://osmocom.org/projects/osmopcu
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Neels Hofmeyr 3de6d0602f fix PACCH paging: don't return early in case of NULL TBF 
Commit b78a4a6dfe tried to fix a NULL dereference
error, but apparently was overly eager to return, because it looked like all
code paths would dereference the tbf.

In fact the code path further above, for msg != NULL, has "always" dereferenced
the tbf, but the lower code path, the one effecting the paging, has only
started to dereference tbf since shortly before the overly eager fix: in
da7250ad2c, to "update the dl ctrl msg counter
for ms". It seems that this tbf dereference in the paging path is bogus and the
cause for the segfault that made me write the early exit fix.

Fix that fix:

Do not exit early if tbf == NULL, stay in there to be able to reach the paging
path below.

In case of a message to be sent, assume that tbf is present, and verify: print
an error message and abort if there is a msg but no tbf, so that we will see
the error if I'm wrong there. If a tbf is missing, free the msg.

In case of no message, go on to send pending pagings, but do not attempt to
count ctrl messages for a tbf -- IIUC there will never be a tbf if we're
paging.

This should avoid segfaults while keeping PACCH paging intact.

Tweak a comment for and add a blank line above the paging section.

Related: OS#2176 CID#158969
Change-Id: Ib79f4a945e211a13ac7d1e511cc37b0940ac6202
 		2017-05-15 10:40:34 +00:00
contrib jenkins: add value_string termination check 2017-03-16 19:01:04 +00:00
debian Add pkg-config file 2017-03-09 12:17:35 +01:00
examples Revert "pcu: Improve default config" 2015-11-30 12:11:48 +01:00
include Support sending OML Alerts via BTS 2017-03-17 17:01:28 +00:00
src fix PACCH paging: don't return early in case of NULL TBF 2017-05-15 10:40:34 +00:00
tests tbf.cpp: use new tlli instead of old tlli 2017-05-01 16:57:48 +00:00
.gitignore Add pkg-config file 2017-03-09 12:17:35 +01:00
.gitreview add .gitreview 2016-05-19 06:39:45 +00:00
COPYING import GPLv2 license text to this project 2012-07-22 22:05:44 +02:00
Makefile.am Update README file with general project info and use Markdown 2017-03-17 17:24:55 +01:00
README.md Update README file with general project info and use Markdown 2017-03-17 17:24:55 +01:00
TODO TODO: Update the todolist with some musings... 2014-01-16 10:11:57 +01:00
configure.ac Add pkg-config file 2017-03-09 12:17:35 +01:00
git-version-gen Add auto-foo (partial cleanup, master makefile/configure.ac 2012-06-14 21:05:44 +08:00
osmo-pcu.pc.in Add pkg-config file 2017-03-09 12:17:35 +01:00
osmoappdesc.py Added conditional python-based tests for VTY/config handling 2013-04-06 11:00:20 +02:00

README.md

osmo-pcu - Osmocom Packet Control Unit

This repository contains a C/C++-language implementation of a GPRS Packet Control Unit, as specified by ETSI/3GPP. It is part of the Osmocom Open Source Mobile Communications project.

The Packet Control Unit is terminating the Layer 2 (RLC/MAC) of the GPRS radio interface and adapting it to the Gb Interface (BSSGP+NS Protocol) towards the SGSN.

The PCU interfaces with the physical layer of the radio interface. OsmoPCU is typically used co-located with the BTS, specifically OsmoBTS. For legacy BTSs that run proprietary sotware without an interface to OsmoPCU, you may also co-locate it with the BSC, specifically OsmoBSC

Homepage

The official homepage of the project is https://osmocom.org/projects/osmopcu/wiki/OsmoPCU

GIT Repository

You can clone from the official osmo-pcu.git repository using

git clone git://git.osmocom.org/osmo-pcu.git

There is a cgit interface at http://git.osmocom.org/osmo-pcu/

Documentation

We provide a user manual as well as a vty reference manual

Please note that a lot of the PCU configuration actually happens inside the BSC, which passes this configuration via A-bis OML to the BTS, which then in turn passes it via the PCU socket into OsmoPCU.

Mailing List

Discussions related to osmo-pcu are happening on the osmocom-net-gprs@lists.osmocom.org mailing list, please see https://lists.osmocom.org/mailman/listinfo/osmocom-net-gprs for subscription options and the list archive.

Please observe the Osmocom Mailing List Rules when posting.

Contributing

Our coding standards are described at https://osmocom.org/projects/cellular-infrastructure/wiki/Coding_standards

We us a gerrit based patch submission/review process for managing contributions. Please see https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit for more details

The current patch queue for osmo-pcu can be seen at https://gerrit.osmocom.org/#/q/project:osmo-pcu+status:open

Current limitations

  • No PFC support
  • No fixed allocation support
  • No extended dynamic allocation support
  • No unacknowledged mode operation
  • Only single slot assignment on uplink direction
  • No half-duplex class support (only semi-duplex)
  • No TA loop
  • No power loop