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This way osmo-msc can benefit from the complete codec information received via
SIP, which was so far terminated at osmo-sip-connector. osmo-sip-connector
could/should have translated the received SDP to MNCC bearer_cap, but this was
never implemented properly. Since osmo-msc already handles SDP towards the MGW,
it makes most sense to pass SDP to osmo-msc transparently.
To be able to send a valid RTP IP:port in the SDP upon the first MNCC_SETUP_IND
going out, move the CN side CRCX to the very start of establishing a voice
call. As a result, first create MGW conns for both RAN and CN before starting.
The voice_call_full.msc chart shows the change in message sequence for MO and
MT voice calls.
Implement cc_sdp.c, which accumulates codec information from various sources
(MS, BSS, Assignment, remote call leg) and provides filtering to get the
available set of codecs at any point in time.
Implement codec_sdp_cc_t9n.c, to translate between SDP and the various
libosmo-mgcp-client, CC and BSSMAP representations of codecs:
- Speech Version,
- Permitted Speech,
- Speech Codec Type,
- default Payload Type numbers,
- enum mgcp_codecs,
- FR/HR compatibility
- SDP audio codec names,
- various AMR configurations.
A codec_map lists these relations in one large data record.
Various functions provide conversions by traversing this map.
Add trans->cc.mnccc_release_sent: so far, avoiding to send an MNCC release
during trans_free() was done by setting the callref = 0. But that also skips CC
Release. On codec mismatch, we send a specific MNCC error code but still want a
normal CC Release: hence send the MNCC message, set mnccc_release_sent = true
and do normal CC Release in trans_free().
(A better way to do this would be to adopt the mncc_call FSM from inter-MSC
handover also for local voice calls, but that is out of scope for now. I want
to try that soon, as time permits.)
Change-Id: I8c3b2de53ffae4ec3a66b9dabf308c290a2c999f
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Use of this flag was dropped when adding inter-BSC and inter-MSC Handover
support, I forgot to remove it.
Change-Id: I5ec78e30eb36fbe78a3f7c46bfa44af5a4eb7bf2
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Change-Id: I07b2b6c0ee33f5d3e0a060c10cf36d5c7c9f0d9b
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For all CC type transaction logging, log the current trans->cc.state string for
all LOG_TRANS*() logging.
Change-Id: I67be12c74c679ce684f8c0b9b4e0d96299849dc6
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Change-Id: I3c373d20ebd6e96ebd57f84b74dc15a6b69c03ac
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According to 3GPP TS 29.002, section 7.6.8.7, MMS (More Messages to Send)
is an optional IE of MT-ForwardSM-Req message which is used by SMSC to
indicate that there are more (multi-part) MT SMS messages to be sent.
The MSC needs to use this indication in order to decide whether to
keep the RAN connection with a given subscriber open.
Related Change-Id: (TTCN) I6308586a70c4fb3254c519330a61a9667372149f
Change-Id: Ic46b04913b2e8cc5d11a39426dcc1bfe11f1d31e
Related: OS#3587
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Previous patch [1] removed NULL-safety from LOG_TRANS(). Fix that.
In case a trans is NULL, it is fine to log in the DMSC category, since the
context should still be general (erratic message or other initial problems).
[1] 7f85acea9bb9f80e208820958f4cae63625f3689 / I6dfe5b98fb9e884c2dde61d603832dafceb12123
"LOG_TRANS: store subsys in trans, unify USSD logging back to DMM"
Change-Id: I6e36c47bf828dd073b36c6301bbeabcc28e101e6
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Change-Id: Id7e04c9f5088334cd5ec6cfdb6a9b3a2a7e7fda0
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Instead of calling trans_log_subsys() for each LOG_TRANS() log line, rather
store in trans->log_subsys once on trans_alloc() and use that.
Do not fall back to the RAN's own subsystem (DBSSAP / DIUCS), it makes little
sense and may cause logging to switch subsystems depending on the RAN state.
In trans_log_subsys(), add missing switch cases:
- Log silent call transactions also on CC.
- Log USSD on DMM.
About USSD: we currently have no dedicated USSD logging category. As a result,
after LOG_TRANS() was introduced [1], USSD logged on DBSSAP/DIUCS or DMSC,
depending on whether a RAN was associated with the trans or not. Before that
change, USSD always logged on DMM, so, until we have a separate logging
category for USSD, consistenly use DMM again.
[1] in I2e60964d7a3c06d051debd1c707051a0eb3101ba / ff7074a0c7b62025473d8f1a950905ac2cb2f31c
Related: coverity CID 198453
Change-Id: I6dfe5b98fb9e884c2dde61d603832dafceb12123
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3GPP TS 49.008 '4.3 Roles of MSC-A, MSC-I and MSC-T' defines distinct roles:
- MSC-A is responsible for managing subscribers,
- MSC-I is the gateway to the RAN.
- MSC-T is a second transitory gateway to another RAN during Handover.
After inter-MSC Handover, the MSC-I is handled by a remote MSC instance, while
the original MSC-A retains the responsibility of subscriber management.
MSC-T exists in this patch but is not yet used, since Handover is only prepared
for, not yet implemented.
Facilitate Inter-MSC and inter-BSC Handover by the same internal split of MSC
roles.
Compared to inter-MSC Handover, mere inter-BSC has the obvious simplifications:
- all of MSC-A, MSC-I and MSC-T roles will be served by the same osmo-msc
instance,
- messages between MSC-A and MSC-{I,T} don't need to be routed via E-interface
(GSUP),
- no call routing between MSC-A and -I via MNCC necessary.
This is the largest code bomb I have submitted, ever. Out of principle, I
apologize to everyone trying to read this as a whole. Unfortunately, I see no
sense in trying to split this patch into smaller bits. It would be a huge
amount of work to introduce these changes in separate chunks, especially if
each should in turn be useful and pass all test suites. So, unfortunately, we
are stuck with this code bomb.
The following are some details and rationale for this rather huge refactoring:
* separate MSC subscriber management from ran_conn
struct ran_conn is reduced from the pivotal subscriber management entity it has
been so far to a mere storage for an SCCP connection ID and an MSC subscriber
reference.
The new pivotal subscriber management entity is struct msc_a -- struct msub
lists the msc_a, msc_i, msc_t roles, the vast majority of code paths however
use msc_a, since MSC-A is where all the interesting stuff happens.
Before handover, msc_i is an FSM implementation that encodes to the local
ran_conn. After inter-MSC Handover, msc_i is a compatible but different FSM
implementation that instead forwards via/from GSUP. Same goes for the msc_a
struct: if osmo-msc is the MSC-I "RAN proxy" for a remote MSC-A role, the
msc_a->fi is an FSM implementation that merely forwards via/from GSUP.
* New SCCP implementation for RAN access
To be able to forward BSSAP and RANAP messages via the GSUP interface, the
individual message layers need to be cleanly separated. The IuCS implementation
used until now (iu_client from libosmo-ranap) did not provide this level of
separation, and needed a complete rewrite. It was trivial to implement this in
such a way that both BSSAP and RANAP can be handled by the same SCCP code,
hence the new SCCP-RAN layer also replaces BSSAP handling.
sccp_ran.h: struct sccp_ran_inst provides an abstract handler for incoming RAN
connections. A set of callback functions provides implementation specific
details.
* RAN Abstraction (BSSAP vs. RANAP)
The common SCCP implementation did set the theme for the remaining refactoring:
make all other MSC code paths entirely RAN-implementation-agnostic.
ran_infra.c provides data structures that list RAN implementation specifics,
from logging to RAN de-/encoding to SCCP callbacks and timers. A ran_infra
pointer hence allows complete abstraction of RAN implementations:
- managing connected RAN peers (BSC, RNC) in ran_peer.c,
- classifying and de-/encoding RAN PDUs,
- recording connected LACs and cell IDs and sending out Paging requests to
matching RAN peers.
* RAN RESET now also for RANAP
ran_peer.c absorbs the reset_fsm from a_reset.c; in consequence, RANAP also
supports proper RESET semantics now. Hence osmo-hnbgw now also needs to provide
proper RESET handling, which it so far duly ignores. (TODO)
* RAN de-/encoding abstraction
The RAN abstraction mentioned above serves not only to separate RANAP and BSSAP
implementations transparently, but also to be able to optionally handle RAN on
distinct levels. Before Handover, all RAN messages are handled by the MSC-A
role. However, after an inter-MSC Handover, a standalone MSC-I will need to
decode RAN PDUs, at least in order to manage Assignment of RTP streams between
BSS/RNC and MNCC call forwarding.
ran_msg.h provides a common API with abstraction for:
- receiving events from RAN, i.e. passing RAN decode from the BSC/RNC and
MS/UE: struct ran_dec_msg represents RAN messages decoded from either BSSMAP
or RANAP;
- sending RAN events: ran_enc_msg is the counterpart to compose RAN messages
that should be encoded to either BSSMAP or RANAP and passed down to the
BSC/RNC and MS/UE.
The RAN-specific implementations are completely contained by ran_msg_a.c and
ran_msg_iu.c.
In particular, Assignment and Ciphering have so far been distinct code paths
for BSSAP and RANAP, with switch(via_ran){...} statements all over the place.
Using RAN_DEC_* and RAN_ENC_* abstractions, these are now completely unified.
Note that SGs does not qualify for RAN abstraction: the SGs interface always
remains with the MSC-A role, and SGs messages follow quite distinct semantics
from the fairly similar GERAN and UTRAN.
* MGW and RTP stream management
So far, managing MGW endpoints via MGCP was tightly glued in-between
GSM-04.08-CC on the one and MNCC on the other side. Prepare for switching RTP
streams between different RAN peers by moving to object-oriented
implementations: implement struct call_leg and struct rtp_stream with distinct
FSMs each. For MGW communication, use the osmo_mgcpc_ep API that has originated
from osmo-bsc and recently moved to libosmo-mgcp-client for this purpose.
Instead of implementing a sequence of events with code duplication for the RAN
and CN sides, the idea is to manage each RTP stream separately by firing and
receiving events as soon as codecs and RTP ports are negotiated, and letting
the individual FSMs take care of the MGW management "asynchronously". The
caller provides event IDs and an FSM instance that should be notified of RTP
stream setup progress. Hence it becomes possible to reconnect RTP streams from
one GSM-04.08-CC to another (inter-BSC Handover) or between CC and MNCC RTP
peers (inter-MSC Handover) without duplicating the MGCP code for each
transition.
The number of FSM implementations used for MGCP handling may seem a bit of an
overkill. But in fact, the number of perspectives on RTP forwarding are far
from trivial:
- an MGW endpoint is an entity with N connections, and MGCP "sessions" for
configuring them by talking to the MGW;
- an RTP stream is a remote peer connected to one of the endpoint's
connections, which is asynchronously notified of codec and RTP port choices;
- a call leg is the higher level view on either an MT or MO side of a voice
call, a combination of two RTP streams to forward between two remote peers.
BSC MGW PBX
CI CI
[MGW-endpoint]
[--rtp_stream--] [--rtp_stream--]
[----------------call_leg----------------]
* Use counts
Introduce using the new osmo_use_count API added to libosmocore for this
purpose. Each use token has a distinct name in the logging, which can be a
globally constant name or ad-hoc, like the local __func__ string constant. Use
in the new struct msc_a, as well as change vlr_subscr to the new osmo_use_count
API.
* FSM Timeouts
Introduce using the new osmo_tdef API, which provides a common VTY
implementation for all timer numbers, and FSM state transitions with the
correct timeout. Originated in osmo-bsc, recently moved to libosmocore.
Depends: Ife31e6798b4e728a23913179e346552a7dd338c0 (libosmocore)
Ib9af67b100c4583342a2103669732dab2e577b04 (libosmocore)
Id617265337f09dfb6ddfe111ef5e578cd3dc9f63 (libosmocore)
Ie9e2add7bbfae651c04e230d62e37cebeb91b0f5 (libosmo-sccp)
I26be5c4b06a680f25f19797407ab56a5a4880ddc (osmo-mgw)
Ida0e59f9a1f2dd18efea0a51680a67b69f141efa (osmo-mgw)
I9a3effd38e72841529df6c135c077116981dea36 (osmo-mgw)
Change-Id: I27e4988e0371808b512c757d2b52ada1615067bd
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Change-Id: I2e60964d7a3c06d051debd1c707051a0eb3101ba
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It may happen that either the MS or an EUSE would become
unresponsive during a call independent SS session, e.g.
due to a bug, or a dropped message. In such cases, the
corresponding transaction would remain unfreed forever.
This change introduces a guard timer, that prevents keeping
'stalled' NCSS sessions forever. As soon as it expires, both
sides (i.e. MS and EUSE) are getting notified, and the
transaction is being released.
By default, the timer expires after 30 seconds. As soon as
either the MS, or an EUSE initiates any activity,
the watchdog timer is rescheduled.
The timeout value can be configured from the VTY:
msc
...
! Use 0 to disable this timer
ncss guard-timeout 30
Please note that changing the timeout value at run-time
doesn't affect the existing NCSS sessions, excepting the
case when the timer is disabled at run-time.
This change makes TC_lu_and_ss_session_timeout pass.
Change-Id: Icf4d87c45e90324764073e8230e0fb9cb96dd9cb
Related Change-Id: (TTCN) I3e1791773d56617172ae27a46889a1ae4d400e2f
Related: OS#3655
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Change-Id: I52787120d5ec59897329d28eab28e0fda3d0f44f
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Change-Id: I2d3a6334f49989bedbb1430d26ffad8b61dfd873
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According to GSM 04.07, the TI flag takes one bit and can be
either of the following:
'0'B - transaction is allocated by sender of a message,
'1'B - transaction is allocated by receiver of a message.
Since we store transaction ID in gsm_trans structure, we also store
TI flag (as a part of transaction ID), which in this context means:
'0'B - transaction is allocated by us (OsmoMSC),
'1'B - transaction is allocated by some MS.
In 100% cases, trans_assign_trans_id() is used to assign transaction IDs
to transactions allocated by us (i.e. OsmoMSC) for MT connections. And
there is no need to use it for MO transactions, because they basically
already do contain a valid transaction ID assigned by the MS.
Change-Id: Ie11999900b1789652ee078d34636dcda1e137eb0
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The need to pass a pointer to RAN connection in order to find
a transaction limits possible use cases of trans_find_by_sm_rp_mr(),
e.g. when we need to find a transaction, but RAN connection is not
established yet.
Moreover, the pointer to RAN connection was only used to obtain
pointers to gsm_network and vlr_subscr, so we can just
pass them directly.
Change-Id: I093f36d63e671e50e54fc6236e97a777cc6da77b
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The flag is set to true when an assignment has been started, and it is only
relevant for a CC transaction. So fix naming and place in cc struct.
Cosmetic preparation for I1f8746e7babfcd3028a4d2c0ba260c608c686c76 and
I0ba216b737909e92080a722db26e3577726c63cb/
Change-Id: I8dacf46141ba0b664e85b0867ade330c97d8495f
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Change-Id: If002a1ff6ba4218cc16592946798340fcb1852ae
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In preparation for inter-BSC and inter-MSC handover, we need to separate the
subscriber management logic from the actual RAN connections. What better time
to finally rename gsm_subscriber_connection.
* Name choice:
In 2G, this is a connection to the BSS, but even though 3GPP TS commonly talk
of "BSS-A" and "BSS-B" when explaining handover, it's not good to call it
"bss_conn": in 3G a BSS is called RNS, IIUC.
The overall term for 2G (GERAN) and 3G (UTRAN) is RAN: Radio Access Network.
* Rationale:
A subscriber in the MSC so far has only one RAN connection, but e.g. for
inter-BSC handover, a second one needs to be created to handover to. Most of
the items in the former gsm_subscriber_connection are actually related to the
RAN, with only a few MM and RTP related items. So, as a first step, just rename
it to ran_conn, to cosmetically prepare for moving the not strictly RAN related
items away later.
Also:
- Rename some functions from msc_subscr_conn_* to ran_conn_*
- Rename "Subscr_Conn" FSM instance name to "RAN_conn"
- Rename SUBSCR_CONN_* to RAN_CONN_*
Change-Id: Ic595f7a558d3553c067f77dc67543ab59659707a
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According to GSM TS 04.11, section 8.2.3, the RP Message Reference
is a mandatory field for all messages on the SM-RL (SM Relay Layer),
that is used to link an RP-ACK or RP-ERROR message to the associated
(preceding) RP-DATA or RP-SMMA message transfer attempt.
This change extends the transaction state structure with SM-RP-MR,
and introduces a new function for matching transactions within a
given connection by this reference.
Change-Id: Ice47c37ecef4416e65ecee8931d946c915316791
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The external MNCC handler may hang indefinitely in cases where the remote
end of the MNCC ceases to work properly. Add a global guard timer to
make sure the call reaches ACTIVE state.
Change-Id: I7375d1e17cd746aac4eadfe1e587e82cf1630d3d
Related: OS#3599
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This change introduces a possibility to establish network-initiated
SS/USSD transactions with a subscriber in either IDLE, or DEDICATED
state. In the first case, a new transaction is established using
Paging procedure. If a subscriber already has an active connection,
a separate new transaction is established.
TTCN-3 test case: I073893c6e11be27e9e36f98f11c1491d0c173985
Change-Id: Ief14f8914ef013bd6efd7be842f81fbf053f02e2
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The DLCI field of the DTAP header indicates the SAPI as well as the
data link (main DCCH or SACCH). We must make sure to use the correct
DLCI when sending DTAP to the BSC.
We achieve this by
* storing the DLCI in the msgb->cb while parsing the DTAP header
* storing the received DLCI (from msgb->cb) in the transaction for
mobile-originated transactions
* using the trans->dlci to sent msgb->cb when transmitting L3
* filling the DTAP DLCI value from msgb->cb when transmitting DTAP
For MSC-originated transactions, we choose a DLCI value corresponding
to the service (SAPI=0 for CC, SAPI=3 for SMS) and store that in
trans->dlci.
Closes: OS#3150
Change-Id: If511b20f52575054cab1346d99a8cb68d827fdbf
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Change-Id: I1f96a1285bbd1b4607614856bca935d5c26e2da9
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