OpenBSC November 2021

openbsc@lists.osmocom.org

18 participants
27 discussions

On the use of 'decmatch' in TTCN-3
by Harald Welte 27 Jan '26

27 Jan '26

Hi, I know that TTCN-3 is still new to a lot of you, but we are writing tons of integration testing against the various osmocom programs in it. It is quite amazing technology, and I would like to ask you to bear with me reading this mail :) Pau was stating the question earlier today on not finding an example on how to use decmatch. Indeed, it took me some months to find that gem in the TTCN-3 world. It solves the problem that you often have during test of layered protocol stacks: you have separate encoders/decoders for each protocol layer, and now you want to match on some of the *inner* payload. So normally, you have some kind of header definition + a binary (octetstring) payload. This happens in RSL with the L3_INFO IE, and just the same on BSSAP/DTAP where again the L3 message (for example call control) is encapsulated inside one information element. Now you have multiple options of addressing the problem: a) hand-written calls to the decoder function b) write na 'emulation' for the entire protocol layer c) use decmatch. a) would look like this (pseudo-code): var octetstring l3oct; var RSL_Message rsl RSL.receive(tr_RSL_DATA_REQ(g_chan_nr, ?, ?)) -> value rsl { var PDU_ML3_MS_NW l3 := dec_PDU_ML3_MS_NW(rsl.payload); if (match(l3, some_template)) { ... do something } ... } Which uses the built-in pattern-matching on the RSL port to match any message that matches the tr_RSL_DATA_REQ template, and stores the resulting RSL message in a variable. It then uses an explicit call to the decoder function of the L3 message, and then uses regular conditional expressions for further matching on that inner L3 payload. This is more or less how you would write in C, python or any other quite imperative programming languages. It's very verbose, time consuming and un-abstract/elegant. TTCN-3 has many declarative aspects to it. Code like the above is a waste of your time :) b) would mean that you implement some test component that handles the RSL messages on its bottom side test port, and the L3 messages on its top side test port. That is a possible way, and if you need a lot of state/logic of RSL, it maeks sense. But what if you really simply want to have a match? Then it would be a lot of effort and a large detour. c) decmatch to the rescue! You can write RSL.receive(tr_RSL_DATA_REQ(g_chan_nr, ?, decmatch tr_RRM_RR_STATUS)) which means: * do a receive on the RSL test port, and match on an incoming RSL message that matches the tr_RSL_DATA_REQ template, with channel number specified, link_id any (?), *and* if the octetstring payload, if decoded, matches the template tr_RRM_RR_STATUS ! This is *extremely* powerful and expressive. It allows you to condense complex, parametric template matching over multiple proocol layers. It would in the end match RSL DATA REQUEST, only if they contained a [valid] encoded RR STATUS. See https://gerrit.osmocom.org/6229 for the actual test case I used for the above examples. Please also note that I never had to even write the function name of the decoder (dec_PDU_ML3_MS_NW), but TTCN-3 *automatically* figures out which decoder function it must call in order to decode from the binary octetstring. Happy (TTCN-3) hacking + Osmocom bugfixing, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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osmo-gsm-manuals in project repos: I see no .pdf
by Neels Hofmeyr 08 Jan '26

08 Jan '26

Hi Oliver, so I merged the stuff to add the manuals to the individual git repositories, since you said that it works. But when I do --enable-manuals I don't see any PDF files generated. Also a manual 'make pdf' says "nothing to be done". (I probably should have tried it before merging after all) So what am I doing wrong? Alternatively, can you fix it please? ~N

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Pysim error: SW match failed
by Martin Nagy 16 Aug '25

16 Aug '25

Hi all, After buying a super Sim Kit (16 in 1) from China, I tried the reader (green PCB inside a blue transparent plastic case with a blue LED) and SIM (identified as a fakesupersim) with pysim tool. However i am getting the following error: /pySim-prog.py -n 26C3 -c 49 -x 262 -y 42 -z 1234 -j 1 -t auto Insert card now (or CTRL-C to cancel) Autodetected card type fakemagicsim Generated card parameters : > Name : 26C3 > SMSP : e1ffffffffffffffffffffffff058100945555ffffffffffff000000 > ICCID : 8949262427518313026 > MCC/MNC : 262/42 > IMSI : 262422461512085 > Ki : 7b74741a1ee14337ec23f9ab92a13648 > OPC : ccd867d60797d8d45354a51b3ef568ff Programming ... Traceback (most recent call last): File "./pySim-prog.py", line 530, in <module> card.program(cp) File "/home/nadicek/pysim/pysim/pySim/cards.py", line 231, in program self._scc.update_binary('6f30', hplmn + 'ff' * (tl-3)) File "/home/nadicek/pysim/pysim/pySim/commands.py", line 53, in update_binary return self._tp.send_apdu_checksw(pdu) File "/home/nadicek/pysim/pysim/pySim/transport/__init__.py", line 87, in send_apdu_checksw raise RuntimeError("SW match failed ! Expected %s and got %s." % (sw.lower(), rv[1])) RuntimeError: SW match failed ! Expected 9000 and got 9804. I checked mailing lists and haven’t found anybody who had similar problem with pysim. Also I have tried forcing different models of SIM, but nothing is working. Obviously I can remove this check from the script file (__init__.py in /pySim/transport), however somebody had a reason to put such condition there. I would like to ask if it is safe to remove that line of code and the purpose of that line of code. Thanks a lot and best regards Martin

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Re: Help with sccp library
by mosbah abdelkader 07 Jul '25

07 Jul '25

> I don't understand. This callback will be called with data you need to write > to the network. In case of MTP Level3 you will need to wrap that around the > msgb you got. I means: is the interaction with mtp3 layer implemented (is sending sccp data by mtp3 implemented by the library?)? Also, what about the reception of data from mtp3 layer. is that implemented in the sccp lib. I am asking these questions because I see the code of mtp3 in the lib but no significant call is present in the sccp part of the lib. Thank you for your help.

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dynamic traffic channels
by Neels Hofmeyr 20 May '25

20 May '25

On Tue, Jun 28, 2016 at 10:05:28AM +0200, Harald Welte wrote: > [translated from german] > is it certain that we switch a channel to PDCH only when > gprs mode != none? A TS can be GSM_PCHAN_TCH_F_PDCH; those are the only ones for which we send a PDCH ACT message. We send a PDCH ACT message - during init (CHANNEL OML's state changed to enabled -> send PDCH ACT), - and upon channel release ack when pchan == GSM_PCHAN_TCH_F_PDCH. So the question is, when we receive a channel release ack, could that be the PDCH release and we switch PDCH right back on by accident? No, because we only receive a chan rel ack when the *TCH/F* is being released. That is because the PDCH release is initiated "internally" from the PDCH DEACT, and thus this condition in common/rsl.c rsl_tx_rf_rel_ack() catches on, which existed before dyn PDCH: if (lchan->rel_act_kind != LCHAN_REL_ACT_RSL) { LOGP(DRSL, LOGL_NOTICE, "%s not sending REL ACK\n", gsm_lchan_name(lchan)); return 0; } In rsl_rx_rf_chan_rel() the rel_act_kind is set to LCHAN_REL_ACT_RSL, but not in the rsl_rx_dyn_pdch(). This is analogous to the ip.access way -- the ip.access nanobts replies to a PDCH DEACT with a PDCH DEACT ACK and doesn't send a separate channel release ack. Maybe we could set rel_act_kind to some new LCHAN_REL_ACT_IPAC_DYN_PDCH for clarity? (But we shouldn't actually send a release ack, to stay compatible.) Even though it works as-is, we should indeed add another flag check: - We do check the flags that no ACT/DEACT is already pending; - And we do send a PDCH DEACT only if ts->flags & TS_F_PDCH_ACTIVE; - But we would send a PDCH ACT despite ts->flags & TS_F_PDCH_ACTIVE. This should never happen, but it would make sense to ensure that. ~Neels

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Problem while running NIB on Open Cellular Base sation
by Brackley Casinga 31 Jan '24

31 Jan '24

Hi, My name is Brackley Cassinga Form DRC, we run a community network called pamoja net where we offer gsm services using osmocom open source software and OC Base station. Recently I have tried to install another base station as the same installed but I could not find any resource guiding through all the steps to take to run NIB on a base station. I'm currently running Ubuntu and I will appreciate if you could guide me on the installation of BSC,hlr,MSC , in order to run a basic gsm network. Thank you. Regards -- *Ir Brackley heshima Casinga **Pacifique* *CEO and Founder of kwanzatechnologie* KwanzaTechnologies ,GlobalElectronics +243977265291 | +243977265291 | Pcassinga(a)gmail.com/ brackley(a)ensemblepourladifference.org www.kwantechnologies.jimdosite.com <http://www.kwantechnologies.com/> | Skype: Brackley cassinga <https://webapp.wisestamp.com/#> Av Semliki N 43

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OsmoDevCon 2022 ?
by Harald Welte 11 Mar '22

11 Mar '22

Dear fellow Osmocom developers, as you all know, we've sadly had to skip OsmoDevCon 2020 and 2021, trying to compensate it at least to some extent with our OsmoDevCall every two weeks. The COVID-19 pandemic is far from over, and we don't know what the upcoming winter season will bring. Nevertheless, I think it would be a good idea to start a discussion of whether we should plan for an OsmoDevCon in 2022. I personally would say let's plan for the usual late April 2022 time frame, and if the pandemic situation deteriorates, we can still cancel it with something like one month lead time. I would also personally suggest to limit attendance to people who are fully vaccinated, and in addition do a self-test for all participants every morning. In terms of venue, we might also consider to move to a venue that allows better ventilation. Irrespective of the above we can also bring the air filters from the sysmocom office. So with that as an input statement, I would like to hear your opinion on the above proposals. Who would want to attend? Any complaints against the "vaccinated only plus daily self-tests in the morning" approach? Regards, Harald -- - Harald Welte <laforge(a)osmocom.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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OSMO-MSC External MNCC integration with FeeSwitch
by Justin 07 Dec '21

07 Dec '21

Hi Osmocom, I'm trying to integrate the FreeSwitch as my external MNCC in my test lab using split stack. Currently, I'm getting an error message on FreeSwitch SIP/2.0 400 Missing Contact Header. I'm little bit confused with the error and I don't know where to troubleshoot this. I've attached my osmo configurations and pcap trace for your reference. Hoping for your reply. Thank you. Regards, Justin Mark Repollo

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AGCH Channel via virtual Um
by Ivan Babanov 28 Nov '21

28 Nov '21

Hello all! I'm sorry for a stupid question, but I can't find an answer by myself. We are using Osmocom solution in University to demonstrate to students how GSM works. We have and fully virtualized workplaces with osm-bts-virtual and osmocom-bb UE via virtual Um. We are making an IMSI Attach procedure and capturing traces with wireshark. Virtual Um messages are visible in wireshark traces with "gsmtap" filter. According standart description, after RACH request UE should receive channel assignment via AGCH channel. But AGCH is not visible in traces. Am I wrong in my expectations somewhere? I tried to filter out messages, tried to filter gsmtap.chan_type == 4 but still no luck. Thank you Vania

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"OsmoDevCall" on Nov 25, 2021: Control/User Plane Separation (CUPS) + PFCP
by Harald Welte 24 Nov '21

24 Nov '21

Dear Osmocom community, It's my pleasure to announce the next OsmoDevCall at November 25, 2021 at 20:00 CET (yes, Thursday instead of Friday this time!) at https://meeting4.franken.de/b/har-xbc-bsx-wvs This meeting will have the following schedule: 20:00 meet + greet 20:10 presentation "Control/User Plane Separation (CUPS) + PFCP" by laforge 21:00 unstructured supplementary social event [*] Attendance is free of charge and open to anyone with an interest in Osmocom or open source cellular technologies. More information about OsmoDevCall, including the schedule for further upcoming events can be found at https://osmocom.org/projects/osmo-dev-con/wiki/OsmoDevCall Looking forward to meeting you on Friday. Best regards, Harald [*] this is how we started to call the "unstructured" part of osmocom developer conferences in the past, basically where anyone can talk about anything, no formal schedule or structure. -- - Harald Welte <laforge(a)osmocom.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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OpenBSC November 2021