Commit Graph

58 Commits

Author SHA1 Message Date
Andreas Eversberg 712b28e695 ASCI: Use a unique call-id for RTP streams
The MGCP protocol features the 'C' (call-id) to identify which
connections belong to the same call. They may be used by MGW for
accounting or management procedures.

So far we sent the MNCC callref as call-id. Instead, add a separate
unique call_id number space. Assign a unique call_id to each
transaction.

Change-Id: I36c5f159fa0b54fb576ff8bd279928b895554793
Related: OS#4854
2023-07-09 07:41:33 +00:00
Oliver Smith 1063213b38 Add initial CSD support with external MNCC
Implement and use CSD bearer service logic (with similar audio codec code):
* csd_filter (codec_filter)
* csd_bs (sdp_audio_codec)
* csd_bs_list (sdp_audio_codecs)

Related: OS#4394
Change-Id: Ide8b8321e0401dcbe35da2ec9cee0abca821d99a
2023-06-20 12:47:05 +02:00
Oliver Smith c63c3a0cc5 transaction: move cc.codecs.result -> cc.local
Prepare for CSD where this will be used too.

Related: OS#4394
Change-Id: Iaf954be0455625faa06a64c19905b79b7045f8e4
2023-06-15 15:06:46 +02:00
Oliver Smith 593cd88535 transaction: move cc.codecs.remote -> cc.remote
Move remote out of codecs, as it will be used by CSD code as well.
Otherwise we would need to store it twice (in cc.codecs.remote and
cc.csd.remote).

Related: OS#4394
Change-Id: I5d2e078db3b3437cb6feae40d8955912d7a297e4
2023-06-15 15:06:46 +02:00
Oliver Smith ceca8e6d2d codec_filter_run: prepare for CSD
Related: OS#4394
Change-Id: I18b396193ad25a3905cc8c1853c9680dab0a2d44
2023-06-15 15:06:46 +02:00
Vadim Yanitskiy 999a593efb copyright: fix typo: sysmocom s/s.m.f.c./s.f.m.c./ GmbH
Change-Id: I81687235fedcbbb686db7def59318e891e00ced7
2023-05-18 17:22:26 +07:00
Neels Hofmeyr 388d7c9374 3G: decapsulate IuUP to AMR at the MGW; allow 3G<-AMR->2G
For all 3G calls, convert IuUP <-> plain AMR/RTP on the MSC's MGW hop
like this:

Before this patch:

 hNodeB <--IuUP--> MGW@hnbgw <--IuUP--> MGW@msc <--IuUP--> other call leg

After this patch:

 hNodeB <--IuUP--> MGW@hnbgw <--IuUP--> MGW@msc <--AMR--> other call leg
                                                    ^

This allows, in principle, 2G to 3G calls without expensive transcoding,
like this:

 hNodeB <--IuUP--> MGW@hnbgw <--IuUP--> MGW@msc <--AMR--> MGW@msc <--AMR--> MGW@bsc <--AMR--> 2G-BTS
                                                    ^
(So far only proven to work with AMR-FR at 12k2.)

3G to 3G calls now look like this:

 hNodeB <--IuUP--> MGW@hnbgw <--IuUP--> MGW@MSC <--AMR--> MGW@MSC <--IuUP--> MGW@hnbgw <--IuUP--> hNodeB
                                                    ^

Implementatino: get rid of the shim that was put in place to still send
IuUP (VND.3GPP.IUFP) to the CN. So now, for all 3G voice, the IuUP gets
decapsulated to plain AMR/RTP at the MSC's MGW hop.

What is proven to work with this patch:
successful voice call between 2G and 3G with these conditions:
- a hNodeB that stubbornly accepts only 12k2 AMR;
- a 2G BTS configured to use only TCH/F and only FR3, with only 12k2 as
  allowed AMR rate.

We have not yet seen a call working for TCH/H HR3 <-> 3G, because of the
lab hNodeB's limitation to 12k2.

Future work we probably need:
- properly request and negotiate AMR rates via SDP fmtp:mode-set.
- request more RFCIs in our RANAP RAB Assignment requests
  (see I61e0e9e75e3239662846fd797532acdefa9f73dc).
- Convert IuUP to AMR already at the HNBGW's MGW?
Solving this is not part of this patch.

Related: SYS#5092
Change-Id: I386a6a426c318040b019ab5541689c67e94672a1
2023-04-05 13:47:46 +00:00
Neels Hofmeyr bd5f8e900b do CN CRCX first
In order to send the MSC's RTP endpoint IP address+port in the initial
SDP, move the MGCP CRCX up to an earlier point in the sequence of
establishing a voice call.

Update the voice call sequence chart to show the effects.

Though the semantic change is rather simple, the patch is rather huge --
things have to happen in a different order, and async waits have to
happen at different times.

The new codec filter helps to carry codec resolution information across
the newly arranged code paths.

Related: SYS#5066
Change-Id: Ie433db1ba0c46d4b97538a969233c155cefac21c
2023-03-18 03:05:34 +01:00
Neels Hofmeyr 11a746acd3 [codecs filter] use codecs filter on crcx ok
Change-Id: I03753df567d1dc24852e6fbb681fbba81d2a545d
2023-03-18 03:05:34 +01:00
Neels Hofmeyr 8dd1646f0b [codecs filter] send + receive SDP via MNCC
Transmit and receive full SDP information via MNCC, to accurately pass
codecs choices between the call legs.

In msc_vlr_test_call.c test_call_mt(), show that when receiving MNCC,
the codec information in SDP overrules the Bearer Cap codec information
-- we expect to still receive inaccurate Bearer Cap from e.g.
osmo-sip-connector, because we have chosen to add SDP to MNCC instead of
trying to fix the codecs represented in Bearer Cap.

For internal MNCC, the MT call leg now knows which codec the MO has
chosen and assigned.

For external MNCC, osmo-sip-connector receives SDP about our codecs
choices and sends it in SIP messages, and we also receive the full SDP
information from the remote SIP leg.

Update the SDP in codec_filter every time it is received, to always have
the latest SDP information from the remote leg.

 CC              MNCC
 | ---ALERTING--> |     add local side SDP to MNCC msg
 | <--ALERTING--- |     store remote side SDP
 | <--SETUP-RESP- |     store remote side SDP
 | --SETUP-CNF--> |     add local side SDP to MNCC msg
 | -RTP-CREATE--> |     use codec_filter, add local side SDP to MNCC msg
 | <-RTP-CONNECT- |     store remote side SDP

There still is one problem: when initiating MNCC, we do not yet know the
RTP address and port to be used for the CN side, because the CN CRCX
happens later. So far we send 0.0.0.0:0 as RTP endpoint in the SDP,
until the CN CRCX is done. A subsequent patch moves CN CRCX to an
earlier time, adding proper RTP information right from the start.

Related: SYS#5066
Change-Id: Ie0668c0e079ec69da1532b52d00621efe114fc2c
2023-03-18 03:05:34 +01:00
Neels Hofmeyr cec51b340e in ran_msg, return gsm0808_speech_codec (intra-MSC)
Do not convert to enum mgcp_codecs, but directly pass the
gsm0808_speech_codec IE from the A interface to codecs handling.

For Iu:
- RAN side: use ran_infra.force_mgw_codecs_to_ran to keep the MGW
  endpoint towards RAN on IUFP.
- CN side: introduce flag ran_msg.assignment_complete.codec_with_iuup,
  so to decide whether to forward IUFP towards CN, we don't need to test
  the RAN type, but use the flag from the ran_msg implementation.

In msc_vlr_tests, use the SDP codec string instead of enum
mgcp_codecs.

So far limit to intra-MSC related messaging, adjusting inter-MSC
handover follows in a separate patch.

Change-Id: Ia666cb697fbd140d7239089628faed93860ce671
2023-03-18 03:05:34 +01:00
Neels Hofmeyr 62bfa37eae rtp_stream: allow multiple codecs / use codec filter from Assignment
Allow configuring MGW conns with multiple codecs. The new codecs filter
can have multiple results, and MGCP can configure multiple codecs. Get
rid of this bottleneck, that so far limits to a single codec to MGW.

On Assignment Complete, set codec_filter.assignment to the assigned
codec, and use that to set the resulting codec (possibly multiple codecs
in the future) to create the CN side MGW endpoint.

Related: SYS#5066
Change-Id: If9c67b298b30f893ec661f84c9fc622ad01b5ee5
2023-03-18 03:05:34 +01:00
Neels Hofmeyr 1dc3961a0a add ran_infra.force_mgw_codecs_to_ran
Indicate in the ran_infra data structure whether a RAN needs specific
codecs to be set up on the RAN facing MGW endpoint.

This allows setting forced RAN codecs as first-class citizen in the
ran_infra data structure, instead of special cases in the code (for IuUP
on IuCS).

Will be used in subsequent commit
I37f65c36af2679ecba1040a11a9aa0eb9481d817, submitted separately for
easier readability.

Change-Id: I37f65c36af2679ecba1040a11a9aa0eb9481d817
2023-03-18 03:05:34 +01:00
Neels Hofmeyr 2d57d6eaa9 [codecs filter] apply BSS codecs from Assignment Complete
Codec List (BSS Supported) is received once in Complete Layer 3 and
again in Assignment Complete messages. Use the most recent one, i.e. the
one from Assignment Complete, when it occurs.

Related: SYS#5066
Change-Id: I5e66ecc7987fa926f39d8be8eaf5799b931ab20a
2023-03-14 22:41:52 +00:00
Neels Hofmeyr e276ae9bc7 [codecs filter] store BSS codec list from Compl L3
The initial Compl L3 happens long before we establish a CC transaction.
Remember the Codec List (BSS Supported), so that we can feed the new
codecs filter with it. Subsequent patches implement feeding the filter.

Related: SYS#5066
Change-Id: I7cdc348218433141a43d2e42750af02591688240
2023-03-14 22:41:52 +00:00
Neels Hofmeyr a818153967 IuCS: remove IuUP LOOPBACK hack
Since osmo-mgw now supports IuUP properly, and since we indicate IUFP in
the MGCP CRCX towars an IuCS RAN [1], we should no longer place the MGW
endpoint in loopback mode to hack up an IuUP Initialization.

This hack should have been removed along with [1].

[1] IUFP sent to MGW since this commit:
commit 3a02d29804
Refs: 1.8.0-13-g3a02d2980
Announce IuFP audio codec for UTRAN conns in CRCX towards MGW
I7aca671e00ed27ac03f0d106b5a6b665a9bed4c1

Change-Id: I6446c64421e3e13e2b829293d031c98b99cd39a7
2023-03-04 03:58:30 +01:00
Neels Hofmeyr ede9083946 comment: clarify L3 Info processing
Related: SYS#5066
Change-Id: Ia9180eeb88b31a2cf7dea72b43affd0c7b239ccb
2023-03-04 03:58:30 +01:00
Neels Hofmeyr 2ea7264b86 msc_a,vlr: add is_ciphering_required (accurately named)
For establishing Layer 3, pass a flag from msc_a to VLR that indicates
to fail if encryption is not possible.

An earlier patch [1] renamed a previously existing flag
require_ciphering to is_ciphering_to_be_attempted, because the naming
was not accurate. This new flag now indicates what its name suggests.

This new flag is needed for upcoming patch [2] to distinguish between
optional and mandatory encryption.

[1] Ia55085e3b36feb275bcf92fc91a4be7d1c24a6b9
[2] I5feda196fa481dd8a46b0e4721c64b7c6600f0d1

Related: OS#4830
Change-Id: I52090c5f5db997030da7c2ed9beca9c51f55f4cf
2022-10-27 23:54:00 +02:00
Neels Hofmeyr d99a607ac9 msc_a,vlr: rename ciphering_required to is_ciphering_to_be_attempted
Clarify the name to avoid confusion in upcoming patches.

This function actually returns whether any ciphering mode besides A5/0
is enabled, and does not imply that ciphering is mandatory. A5/0 may
well be allowed when this function returns true.

Related: OS#4830
Change-Id: Ia55085e3b36feb275bcf92fc91a4be7d1c24a6b9
2022-10-27 23:30:30 +02:00
Neels Hofmeyr 550506aaf1 err log: fix reverse statement in msc_a call handling
Change-Id: I937abe25ba87d0fcddc3351ac391cf6e7e776de6
2022-07-22 19:11:18 +02:00
Neels Hofmeyr 5d53c6001d fix crash on CM Serv Rej: fix use count mismatch
With comments, clarify the code paths where a CM Service use count has
not yet been placed on the conn (just send CM Service Reject) and where
the use count is placed (decrement count on CM Service Reject).

Place the CM Service use count slightly earlier:
- it is then correctly present when checking the mobile identity in
  cm_serv_reuse_conn(), avoiding the crash reported in OS#5532.
- there is only one place incrementing the use count instead of two.

Related: OS#5532
Change-Id: I6c735b79b67108bcaadada3f01c7046e262f939b
2022-05-04 23:43:11 +02:00
Pau Espin 9de384a28c Avoid setting audio codec if not available during assignment_complete (MDCX)
RAB Assignment Complete contains no codec info, hence
assignment_complete.codec is not set and
assignment_complete.codec_present is false.
As a result a wrong value is passed to rtp_stream_set_codec.

This fixes osmo-msc sending "a=rtpmap:112 AMR/8000/1" during MDCX in the
RAT-side connection of the call leg after having properly sent
VND.3GPP.IUFP/16000 in CRCX.

Change-Id: Ic028d35893d29f7d72f22f82ef89695229c9b01b
2022-01-07 18:50:15 +01:00
Pau Espin 3a02d29804 Announce IuFP audio codec for UTRAN conns in CRCX towards MGW
This way the MGW knows it has to handle IuUP in that connection (answer
IuUP Initialization, etc.).

Depends: osmo-mgw.git 1de5ed6f979bd4c1380789c9a82f8e396f05c5f8
Change-Id: I7aca671e00ed27ac03f0d106b5a6b665a9bed4c1
2022-01-05 13:58:15 +01:00
Vadim Yanitskiy c44342b88c libmsc: fix memory leak (struct msgb) in msc_i_ran_enc()
Function msc_i_ran_enc() calls msc_role_ran_encode(), but unlike the
other callers of this function it does not free() the encoded message.

A simple solution would be to call msgb_free(), like it's done in
the other places.  But a more elegant solution is to modify function
msc_role_ran_encode(), so that it attaches the msgb to OTC_SELECT.
This way there is no need to call msgb_free() here and there.

This change fixes a memleak observed while running ttcn3-msc-test.

Change-Id: I741e082badc32ba9a97c1495c894e1d22e122e3a
Related: OS#5340
2021-12-07 18:43:00 +03:00
Alexander Couzens 2c5e46104e libmsc/gsm_04_08: refactor require ciphering into an own function
Make it more readable.

Change-Id: I9e407f65b282e645feabe714f7f4c3e44fae21e9
2021-11-27 04:39:34 +01:00
Alexander Couzens 2aaff7513b Validate the choosen UTRAN encryption algorithm
RANAP Security Command can include an encryption IE. If it includes
it the RNC can still ignore it (e.g. unsupported encryption) and
return the Security Command Complete with an choosen encryption IE:
"no encryption".
Validate the encryption element and ensure the encryption is included in
the encryption mask.

Closes: OS#4144
Change-Id: Icfc135c8b8ae862defe7114db492af600c26407f
2021-11-05 01:29:05 +01:00
Harald Welte 505a94a610 Make UTRAN encryption algorithms configurable
Allow the user fine-grained control over which UMTS encryption
algorithms are permitted, rather than always permitting UEA1 and UEA2
or neither.

This brings the handling of UEA in line with the handling of A5 for
GERAN.

Change-Id: I91f9e50f9c1439aa19528f887b83ae9de628fcfd
Closes: OS#4144
Depends: osmo-iuh.git I6d2d033b0427bdc84fee61e0f3cb7b29935214bf
2021-11-05 01:29:05 +01:00
Harald Welte 274b70f1a8 Fix enabling of UMTS UEA encryption
The existing code allowed the user to configure UMTS encryption in the
vty, but we never actually passed this information down to RANAP.  As a
result, the RAN had no chance of ever enabling encryption on the air
interface.

Change-Id: Ieaaa6b23b7337b7edb902fad8031e195e0c5e9d2
Related: OS#4144
2021-11-05 01:29:05 +01:00
Keith Whyte a1a70be593 Add support for LCLS to the MSC
This commit is largely based on work by
Max <msuraev@sysmocom.de>

Adds LCLS parameters for A-interface transactions
This commit also adds a vty option to facilitate globally
disabling LCLS for all calls on this MSC.

Add a global call reference (GCR) to MNCC and therefore
bump the MNCC version to version 8. (This commit has to be
merged at the same time as the corresponing commit in the
osmo-sip-connector for mncc-external use.)

Depends: osmo-sip-connector Id40d7e0fed9356f801b3627c118150055e7232b1
Change-Id: I705c860e51637b4537cad65a330ecbaaca96dd5b
2021-10-25 10:07:48 +00:00
Neels Hofmeyr ae98b97382 implement CM Re-Establish for voice calls
Related: SYS#5130
Change-Id: I6fa37d6ca9fcb1637742b40e37b68d67664c9b60
2021-07-29 22:40:59 +02:00
Pau Espin e53ecde83e msc_a.c: Allow MSC_A_EV_CN_CLOSE in state MSC_A_ST_RELEASING
As seen in a running osmo-msc:
"vlr_access_req_fsm.c:153
msc_a(IMSI-....:MSISDN-...:TMSI-0x...:GERAN-A-8:CM_SERVICE_REQ){MSC_A_ST_RELEASING}:
Event MSC_A_EV_CN_CLOSE not permitted"

Also seen in several unit tests, which need update.

The action event handler for that state is actually already
expecting/handling the event by ignoring it, so we should allow it.

Change-Id: I4d30cffab693529aab3ba736419dec116a4dd7ef
2021-07-12 16:37:24 +02:00
Neels Hofmeyr 73d093a806 improve logging on encryption, for Ciphering and HO
log the algorithm and all keys instead of just Kc.

Change-Id: If7871dedda2b1fb115e6f00da1379ff2e3d68a10
2021-06-24 01:44:20 +02:00
Neels Hofmeyr 6ce2edcac1 support A5/4 in Cipher Mode Command
Related: SYS#5324
Change-Id: I780a739b9bfbefd4f58be051794fe1a491823e67
2021-06-24 01:27:47 +02:00
Vadim Yanitskiy 435f67f43c msc_tx_common_id(): fix potential NULL pointer dereference
Reported by GCC 11.1.0.  msc_a_vsub() may return NULL.

Change-Id: Iebdd6399e819a03258398e6b7b453bda37e45a20
2021-06-06 15:50:42 +02:00
Pau Espin 2e21a68e83 Use new osmo stat items/ctr APIs
Generated using several semantinc patches with spatch.

Change-Id: I3ee853539949a763a309856bf2e7196415b23741
2021-06-04 16:53:16 +02:00
Pau Espin 6710670cb1 Fill Last Used E-UTRAN PLMN Id when in CSFB
Since recently, osmo-bsc behaves strictly as per specs, meaning it will
only send the "Cell selection indicator after release of all TCH and SDCCH IE"
in RR Channel Release iff:
* "Last Used E-UTRAN PLMN Id" was received in the CommonID sent MSC->BSC
* "Last Used E-UTRAN PLMN Id" was received insider "old BSS to new BSS Information"
  in the HandoverRequest sent MSC->BSC.
On the other hand, CSFB_Indicator from ClearCommand MSC->BSC is nw
ignored and not taken into account.

Hence, let's update osmo-msc to also behave correctly by sending the
Last Used E-UTRAN PLMN ID at CommonID tx time to avoid regressions in
CSFB support when running against newer osmo-bsc.

Let's keep sending the CSFB Indicator in ClearCommand as we used too, in
order to keep compatibility with older BSCs (as per spec).

Related: SYS#5337
Change-Id: Ic5f175b179973d0a50d94f00e15f5a3e332605fc
2021-04-29 14:22:33 +02:00
Neels Hofmeyr d9fe7110ea Clear Command: set cause value to "Call Control"
So far, by failing to initialize the cause value, we always send a Clear
Command cause == 0, which actually means "Radio Interface Message Failure".
This is seen in all my logged network traces of osmo-msc lab testing.

"Call Control" seems to be the only cause value that remotely fits a normal
release procedure, even if it was not voice call related, see 3GPP TS 48.008
3.2.1.21.

Related: OS#4664
Change-Id: I1347ed72ae7d7ea73a557b866e764819c5ef8c42
2020-07-28 18:29:58 +02:00
Neels Hofmeyr 83cf10c8a6 propagate Compl L3 Info Cell ID to the VLR subscriber record
As soon as the subscriber is authenticated, update the VLR entry with the
MSC-A's full CGI, including the Cell Id received from the Complete Layer 3
Information.

Thus the Cell Id will be shown by vty 'show subscriber cache' and 'show
connection'.

This is tested by osmo-ttcn3-hacks Ie410714a96353f74a52a104c56fa0a08683e0004.

Related: OS#4627
Change-Id: Iee1781985fb25b21ce27526c6a3768bf70d4dc9a
2020-06-24 19:22:30 +02:00
Neels Hofmeyr 68f50dad76 add comments to clarify some complete l3 details
Change-Id: I6e289900d38d97c346d615b71d36656254e6f2b5
2020-06-24 14:22:52 +02:00
Philipp Maier f34d945f4f msc_a: add callref as call id to ASSIGNMENT REQ.
The BSSMAP message ASSIGNMENT REQUEST may contain an optional CALL
IDENTIFIER IE. While this IE is optional some BSC implementions may
require it.

Change-Id: I4288f47e4a6d61ec672f431723f6e72c7c6b0799
Related: OS#4582
2020-06-22 16:00:04 +00:00
Neels Hofmeyr 46d526a3df use new osmo_mobile_identity API everywhere
Depends: Ic3f969e739654c1e8c387aedeeba5cce07fe2307 (libosmocore)
Change-Id: Idfc8e576e10756aeaacf5569f6178068313eb7ea
2020-06-19 03:58:13 +02:00
Neels Hofmeyr 00a476bc24 msc_a CC: add some basic sanity tests
Change-Id: I9d7d7d4073282abc6c02a6a297c807dc70c5154c
2019-11-28 02:46:05 +01:00
Neels Hofmeyr cc918cb416 fail on invalid RTP address from MGW
When the CRCX OK returns an invalid RTP address, abort the call; fixes
MSC_Tests.TC_invalid_mgcp_crash.

The original crash happened when adding this error handling without this commit
I08c03946605aa12e0a5ce8b3c773704ef5327a7a ("fsm: use deferred deallocation" for
osmo-mgw I7df2e9202b04e7ca7366bb0a8ec53cf3bb14faf3 "fix use-after-free: require
new fsm deferred dealloc, check for term"). With this error handling added,
even though avoiding a crash, the test does not pass yet, because instead of
rejecting the call, it currently composes an Assignment Command without a
Transport Layer Address. Fix that.

Change-Id: I00c3b5ff74c05bcc2b7c39375c33419916a57193
2019-11-28 02:45:40 +01:00
Martin Hauke 3f07daceef Fix some typos
Fix typos and common misspellings in code comments and log messages.

Change-Id: Ie66b89065f2100c1d2125ce5a6c9b1d58df7c8ad
2019-11-19 01:04:34 +00:00
Neels Hofmeyr f439ff121f CC: add error handling for CRCX responses
Fix three 'FIXME: ERROR HANDLING' occurences in the code that reacts upon the
MGW providing (or failing to provide) an RTP port for the RAN side. From an
earlier stage of the code, the cleanup for this situation was extremely
complex, and hence the choice was to simply wait for the call to time out and
fail. But since we have implemented safe deallocation of nested FSMs in
libosmocore, the situation has become rather trivial: simply free the CC
transactions, and all the rest will immediately release, and terminate
correctly without crashing.

A ttcn3 test for this is MSC_Tests:TC_invalid_mgcp_crash, which actually also
needs the change to osmo_sockaddr_str_is_nonzero() in preceding patch
I53ddb19a70fda3deb906464e1b89c12d9b4c7cbd, so that a seemingly valid MGCP
message ends up causing a failure in the on_success() branch of
mgcp_client_endpoint_fsm.c.

Change-Id: I8313bed1d782100bebeac7d8fc040557c4cb653e
2019-11-01 17:35:17 +01:00
Neels Hofmeyr c192c0bf71 log which DTAP messages are sent to RAN
So far, the logging said only "RAN encode: BSSMAP: DTAP", but not *which* DTAP
message, which is in fact a very interesting detail when reading osmo-msc logs.

Change-Id: I0cb8d1e3307737ffe53730c64bb984adacedb2da
2019-10-21 00:40:31 +02:00
Neels Hofmeyr e9a3911844 fix error on BSSMAP Cipher Mode Complete L3 msg IE
When an MS returns the IMEISV in the BSSMAP Cipher Mode Complete message in
the Layer 3 Message Contents IE, do not re-invoke the decode_cb() a second
time, but instead point to it from the ran_msg.cipher_mode_complete struct.

When the MSC-A decodes the Ciphering Mode Complete message, it always wants to
also decode the enclosed DTAP from the Layer 3 Message Contents IE. However,
when the MSC-I preliminarily decodes messages, it often just wants to identify
specific messages without fully acting on them, let alone dispatching RAN_UP_L2
events more than once. So leave it up to the supplied decode_cb passed to
ran_dec_l2() implementations to decide whether to decode the DTAP.

In msc_a.c hence evaluate the DTAP by passing a msgb to msc_a_up_l3(), which
will evaluate the RR Ciphering Mode Complete message found in the BSSMAP Cipher
Mode Complete's Layer 3 Message Contents IE.

Particularly, the previous choice of calling the decode_cb a second time for
the enclosed DTAP caused a header/length parsing error: the second decode_cb
call tried to mimick DTAP by overwriting the l3h pointer and truncating the
length of the msgb, but subsequently ran_a_decode_l2() would again derive the
l3h from the l2h, obliterating the intended re-interpretation as DTAP, and
hence the previous truncation caused error messages on each and every Cipher
Mode Complete message, like:

DBSSAP ERROR libmsc/ran_msg_a.c:764 msc_a(IMSI-26242340300XXXX:MSISDN-XXXX:TMSI-0xA73E055A:GERAN-A-77923:LU)[0x5563947521e0]{MSC_A_ST_AUTH_CIPH}: RAN decode: BSSMAP: BSSMAP data truncated, discarding message

This error was seen a lot at CCCamp2019.

Modifying the msgb was a bad idea to begin with, the approach taken in this
patch is much cleaner.

Note that apparently many phones include the IMEISV in the Cipher Mode Complete
message even though the BSSMAP Cipher Mode Command did not include the Cipher
Response Mode IE. So, even though we did not specifically ask for the Cipher
Mode Complete to include any identity, many MS default to including the IMEISV
of their own accord. Reproduce: attach to osmo-msc with ciphering enabled using
a Samsung Galaxy S4mini.

Related: OS#4168
Change-Id: Icd8dad18d6dda24d075dd8da72c3d6db1302090d
2019-09-18 15:31:13 +02:00
Neels Hofmeyr 01653252b4 msc_a fsm: ignore state chg to same state
We sometimes see errors like

   libmsc/msc_a.c:361 msc_a(...){MSC_A_ST_RELEASING}: transition to state MSC_A_ST_RELEASING not permitted!

i.e. changing state to the state msc_a is already in.

Ignore re-entering the same state for most state changes. However, there is one
state change in msc_a where re-entering the MSC_A_ST_VALIDATE_L3 is necessary
to start the timeout.

Hence add msc_a_state_chg_always() and use that for re-entering
MSC_A_ST_VALIDATE_L3. Change msc_a_state_chg() to skip no-op state changes.

This should silence all no-op state change error messages for msc_a.

Related: OS#4169
Change-Id: I0c74c10b5fa7bbdd6ae3674926cc0393edf15a35
2019-09-03 13:59:05 +00:00
Neels Hofmeyr b4ef5e7bd1 msc_a.c, CC trans: change a comment to a debug log
Change-Id: I5a3cc6219080910119b0c9ff11fc2b9eb96a06e5
2019-09-02 11:07:49 +02:00
Neels Hofmeyr 2e8f881f72 fix segfault: don't send CC REL on NULL msc_a
Apparently, if a conn disappears during an ongoing call, the CC code tried to
send a CC REL on a NULL msc_a during cleanup, which lead to a crash
(cccamp2019). Guard against that.

Crash:

 #0  msc_a_tx_dtap_to_i (msc_a=0x0, dtap=0x55a4bf2fa0f0) at ../../../../src/osmo-msc/src/libmsc/msc_a.c:1565
 #1  0x000055a4be1bb03c in trans_tx_gsm48 (trans=0x55a4bf2d52a0, trans=0x55a4bf2d52a0, trans=0x55a4bf2d52a0, msg=<optimized out>)
     at ../../../../src/osmo-msc/src/libmsc/gsm_04_08_cc.c:82
 #2  gsm48_cc_tx_release (trans=trans@entry=0x55a4bf2d52a0, arg=arg@entry=0x7ffdd731a0e0) at ../../../../src/osmo-msc/src/libmsc/gsm_04_08_cc.c:1101
 #3  0x000055a4be1bee65 in _gsm48_cc_trans_free (trans=trans@entry=0x55a4bf2d52a0) at ../../../../src/osmo-msc/src/libmsc/gsm_04_08_cc.c:278
 #4  0x000055a4be1ab654 in trans_free (trans=trans@entry=0x55a4bf2d52a0) at ../../../../src/osmo-msc/src/libmsc/transaction.c:170
 #5  0x000055a4be1bd091 in mncc_tx_to_gsm_cc (net=<optimized out>, msg=msg@entry=0x55a4bf2d3b68)
     at ../../../../src/osmo-msc/src/libmsc/gsm_04_08_cc.c:1971
 #6  0x000055a4be1bf1e5 in mncc_tx_to_cc (net=<optimized out>, arg=arg@entry=0x55a4bf2d3b68)
     at ../../../../src/osmo-msc/src/libmsc/gsm_04_08_cc.c:2049
 #7  0x000055a4be18ed63 in mncc_sock_read (bfd=0x55a4bf2563b8, bfd=0x55a4bf2563b8) at ../../../../src/osmo-msc/src/libmsc/mncc_sock.c:121
 #8  mncc_sock_cb (bfd=0x55a4bf2563b8, flags=1) at ../../../../src/osmo-msc/src/libmsc/mncc_sock.c:189
 #9  0x00007fcfad607ce1 in osmo_fd_disp_fds (_eset=0x7ffdd731a9a0, _wset=0x7ffdd731a920, _rset=0x7ffdd731a8a0)
     at ../../../src/libosmocore/src/select.c:223
 #10 osmo_select_main (polling=<optimized out>) at ../../../src/libosmocore/src/select.c:263
 #11 0x000055a4be17dd56 in main (argc=3, argv=<optimized out>) at ../../../../src/osmo-msc/src/osmo-msc/msc_main.c:723

Change-Id: Ia1bb0410ad0618c182a5f6da06af342b6d483eff
2019-08-29 05:42:02 +00:00