Commit Graph

243 Commits

Author SHA1 Message Date
Harald Welte 4f155022d8 cbsp: Add osmo_cbsp_segmentation_cb for message segmentation
This call-back can for example be used as segmentation call-back
for libosmo-netif stream_cli/stream_srv or directly for osmo_io.

Related: OS#5755
Change-Id: I5e922c54b3431d759b38e81e55076125c5a34008
2024-03-02 20:48:23 +01:00
Harald Welte be3c38ca55 Add a GSM RLP decoder and encoder
This code implements a decoder and encoder for the RLP (Radio Link
Protocol) as used in the bearer channel of GSM CSD (Circuit Switched
Data).

Change-Id: I2d9bd8eb4f0cd0f72c436996767b199429596917
2023-11-29 14:35:36 +00:00
Andreas Eversberg 2d7119d85b LAPDm: Add support for RTS based polling
The lower layer must set the 'POLLING_ONLY' flag and provide frame
number when polling a frame. If T200 is pending, it is started with a
timeout frame number in advance to given frame number.

The lower layer must call lapdm_t200_fn() after a frame has been
received or if a frame has not been received. Also it must be called
after a TCH frame has been received. LAPDm uses this to check the T200
timeout condition.

A new function is used to set the frame number based timeout values.

Related: OS#4074
Change-Id: I6ebe83f829d7751ea9de1d90eb478c7a628db64c
2023-11-27 16:25:53 +00:00
Vadim Yanitskiy a7d7cf284d gsm_12_21.h: add flags for NM_ATT_IPACC_SUPP_FEATURES
Change-Id: Ia4208e10d61843dd6ae77398f6624c918dc81ea4
2023-09-05 19:04:58 +07:00
Pau Espin aea78a2483 gsm: Introduce functions to convert between FN and RFN (Reduced FN)
Implementation ported from osmo-pcu.git
e98b315d12fb009359410809f4169f9380f3d933, function bts_rfn_to_fn().

This functionality can be used by osmo-pcu, libosmo-gprs or any other
related code which needs to handle RFNs.

Change-Id: Ib71e8da976f6cc84c3a4ab17b0a8c2101492e243
2023-08-11 20:46:04 +02:00
arehbein 4ff5db2839 Revert "gsm/ipa: Add segmentation callback"
It has been decided that the segmentation callback be changed
and moved to libosmo-netif, so we remove it here.

This reverts commit 2c59d1285e.

Related: OS#5753
Change-Id: I9b380326c63587fc79d6a5d8cd458188074fc55d
2023-07-18 09:55:26 +00:00
Sylvain Munaut c87c6a3a73 gsm: Improve the TCH/H2.4 coding routines
The spec isn't super clear, but basically the conv coding is done
in two blocks of 72 bits.

The way it's currently implemented isn't "wrong" in the sense it will
produce correct output given no bit errors, but it's better to do the
decoding in two blocks because this then it makes use of the fact we
know the state of the encoder after the 72 bits, which improves the
corrective ability of the code.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Change-Id: Id2551ffe2a0ebfd0a6df0e1d288a6f0af7e1eda7
2023-07-07 16:06:26 +02:00
Vadim Yanitskiy 418d76c2cb gsm: add gsm0502_fn2ccch_block()
This API is useful for checking whether a Downlink CCCH block belongs
to PCH or AGCH.  We need this API in osmo-bts.git and osmocom-bb.git.

Change-Id: I8cbd31226754e95887358ed83a928e2f567f4cf3
Related: OS#5500
2023-06-25 08:45:26 +00:00
arehbein 2c59d1285e gsm/ipa: Add segmentation callback
Add segmentation callback to be used by the streaming backend of libosmo-netif

Related: OS#5753, OS#5751
Change-Id: I3a639e6896cc3b3fc8e9b2e1a58254710efa0d3f
2023-06-19 18:30:47 +00:00
Andreas Eversberg 532b8e92c5 ASCI: Add message definition and encoding according to 3GPP TS 48.008
Change-Id: Ib94c64136c31ce4af67c314a8550d93946cc844f
2023-06-09 15:06:34 +00:00
Neels Hofmeyr 8d42394c89 improve API for osmo_routing_area_id
Code review for [1] has asked for providing proper API for struct
osmo_routing_area_id.

For historical reasons, we have struct gprs_ra_id and
struct osmo_routing_area_id serving the exact same purpose: represent a
decoded 3GPP TS 24.008 § 10.5.5.15 Routing area identification.

The "better" one is struct osmo_routing_area_id: it allows using API
like osmo_plmn_cmp(), because it is made up of meaningful sub-structs.

Implement de/coding using the functions already available for the
sub-struct osmo_location_area_id, and simply add the RAC.

Add a test in gsm0408_test.c.

Note that other utility functions are already available for struct
osmo_routing_area_id: osmo_rai_name2(), osmo_rai_cmp().

There is no real need to deprecate struct gprs_ra_id, because there is
not really anything wrong with it. It just isn't as well integrated with
other utility API as struct osmo_routing_area_id is. Just add comments.

[1] osmo-hnbgw.git:
    cnpool: extract Mobile Identity from RANAP payload
    https://gerrit.osmocom.org/c/osmo-hnbgw/+/33133
    I373d665c9684b607207f68094188eab63209db51

Change-Id: Ic5e0406d9e20b0d4e1372fa30ba11a1e69f5cc94
2023-06-08 00:55:40 +02:00
Harald Welte 76f4c5cf5c libosmogsm: Factor out the C2 derivation function
3GPP specifies the C2 derivation function (generating GSM SRES from UMTS XRES)
independent of the MILENAGE algorithm.  So instead of open-coding it in
milenage.c:gsm_milenage(), let's create a separate public function
osmo_auth_c2() similar to the already-existing osmo_auth_c3() function.

gsm_milenage() can then simply use that function.

Change-Id: I0e7cd55f5578f891cb6cc1b0442920ba5beddae4
2023-06-02 08:29:55 +00:00
Harald Welte 08450c9ec6 libosmogsm: Support authentication with 256-bit K and/or OP/OPc
3GPP TS 33.102 Section 6.3.7 states that K can be 128 or 256 bits,
while our 'struct osmo_sub_auth_data' had a fixed-size 128bit field.

This means we cannot use our auth_core for algorithms with larger
key sizes, such as TUAK.  Let's introduce osmo_sub_auth_data2 for
larger (and variable) sized K and OP[c].

K and OP[c] can even have different sizes in TUAK, where OP[c] is
always 256bit, but K can be 128 or 256 bits.  So we need separate
length fields for K and OP[c].

I'm adding backwards-compatibility API wrappers, so old applications
just continue to work as they always did.

However, I'm not adding compatibility wrappers for the plug-in API
that can be used to register additional authentication implementations
at runtime.  We don't know of any user of that API outside of
libosmocore, so the function signatures of the 'struct osmo_auth_impl'
are modified in an incompatible way.

Change-Id: Ie775fedba4a3fa12314c0f7c8a369662ef6a40df
2023-06-02 08:29:55 +00:00
Andreas Eversberg 5c7336ce88 ASCI: Add IE transcoding according to 3GPP TS 48.008
Change-Id: Ic1fc714bb04228a7f32e9925811e21c8efc610bd
2023-06-02 08:28:49 +00:00
Andreas Eversberg 19b0bb7dd2 ASCI: Add 3GPP TS 44.068 and 44.069 protocol definitions
Change-Id: I3554cea47e714c8fca18c3e9c0e6e80695915a90
2023-06-02 08:28:49 +00:00
Harald Welte 1192687620 Add osmo_gsm48_si1ro_nch_pos_{encode,decode} functions
These functions encode/decode the NCH position field within the SI1
rest octets.  This is used within ASCI (VBS/VGCS).

Change-Id: I24a0095ac6eee0197f9d9ef9895c7795df6cdc49
Related: OS#5781
2023-05-22 10:33:10 +00:00
Neels Hofmeyr e25786ab6a gsm: add osmo_mobile_identity_decode_from_l3_buf()
We have osmo_mobile_identity_decode_from_l3(), which takes a msgb as
argument, and decodes msg->l3h. Not all callers have their data in this
form. Offer a more flexible API for the same decoding.

For example, before the new function, osmo-hnbgw, which extracts a NAS
PDU from asn.1 packed data for CN pooling, would allocate a new msgb and
copy the NAS data just to pass a data pointer as argument.

Related: SYS#6412
Change-Id: I9bd99ccd01f0eedc091fe51687ff92ae1fdff60b
2023-05-06 03:49:08 +00:00
Harald Welte c4cfb802df gsm: TS 44.021 modified V.110 frame encoding/decoding support
3GPP TS 44.021 specifies the format for modified V.110 frames as used
on the GSM air (radio) interface.  Implement encoders and decoders for
this modified V.110 format.

Related: OS#1572
Change-Id: I60a2f2690459359437df20cf4da9043fa7c3ad11
2023-03-08 20:43:15 +01:00
Neels Hofmeyr 593d20d637 add gsm0808_amr_modes_from_cfg
Provide the definitions from 3GPP TS 28.062, Table 7.11.3.1.3-2 as
generally usable API.

Likely users:
- upcoming patch to improve conversion between S0-S15 and MultiRate
  config, I900fda192742fa8f6dd54e9131ef1704b14cc41a
- osmo-msc to figure out conversion between SDP AMR mode-set and 3GPP TS
  48.008 Permitted Speech S0-S15.
- osmo-bsc to choose AMR modes for channel activation from cfg /
  permitted speech from MSC.

Related: SYS#5066
Change-Id: Icef7dd626d3d4641c66b8dd87e2047fc0ab547d1
2023-02-28 23:00:45 +00:00
Harald Welte 65e0edc73f convolutional coding for CSD
This patch adds the convolutional code definitions for CSD (circuit
switched data) on TCH/F channels with user bit rates of 2400, 4800, 9600
and 14400 bps.

Related: OS#4396, OS#1572
Change-Id: I412131d7ee2e676402bf8d88394af17c4447b664
2023-02-25 19:37:44 +01:00
Max bc12728679 SI: add missing header
Previous SI10 patch added function without exposing it via public header.
Let's fix this.

Fixes: 600d4eeab7
Change-Id: Ia7530e9c8a21f6f99f3aac7baea5cbb38763c4f3
2023-01-30 18:52:41 +00:00
Vadim Yanitskiy 5a51331729 gsm0808: add gsm0808_enc_speech_codec[_list]2()
The problem with most of the existing gsm0808_* functions in this file
is that they assert() too much, assuming that their callers always pass
perfectly valid input parameters.  But this is impossible on practice,
as there can be bugs in complex projects using them, liks osmo-bsc.

It was reported by a customer that a heavily loaded osmo-bsc crashed a
few times, dropping more than 100 sites without network coverage for
a few minutes.  As was revealed during the investigaion, it crashed
due to a failing assert at the end of enc_speech_codec():

  OSMO_ASSERT(sc->cfg == 0);

The problem is that somehow osmo-bsc is passing an unexpected sc->cfg
value to gsm0808_create_ass_compl2(), in particular 0x02, while the
given sc->type value (GSM0808_SCT_HR1) implies that there cannot be
any configuration bits on the wire.

The reason why and under which circumstances this can be happening
is not clear yet, but what we agreed on so far is that the library
API should be enforcing correctness of the input parameters in a
less agressive way, rather than aborting the process without
letting it any chance to recover.

Modify the original gsm0808_enc_speech_codec[_list]() functions, so
that a negative value is returned in case of an error.  Rename them
and add backwards compatibility wrappers, because it's public API.

A separate patch making use of the new API follows next.

Change-Id: I199ffa0ba4a64813238519178155dfc767aa3975
Related: SYS#6229
2022-12-14 03:24:51 +07:00
Harald Welte 9fe1f9fb0b Introduce CRC and FSM for IuUP (user plane) as used in 3G RTP data
Only support for SMpSDU mode is introduced in this commit.

Not supported explicit list:
- Transparent mode
- ATM/AAL2 based Transport layer
- GTP-U based Transport Layer
- Iu Rate Control procedure
- Time Alignment procedure

APIs are provided to allocate the primitives properly inside the related
msgb. This way primitives can be placed in the headroom, leaving the
data part of the msgb for the IuUP payload, hence allowing re-use of the
msgb and 0 copy of IuUP payload when forwarding data over RNL<->TNL.
Since RNL and TNL primitives relu struct osmo_prim_header, which is not
packed, they cannot be set to packed, and hence proper memory alignment
in the msgb must be done to avoid misaligned accesses (Asan errors about
it otherwise).

Related: SYS#5516
Change-Id: Ibe356fa7b1abaca0091e368db8478e79c09c6cb0
2021-12-22 14:58:31 +01:00
Neels Hofmeyr 4a9756c17a add Kc128 to gsm0808 Create Ciphering Command
Prepare for A5/4 support in osmo-msc.

Add new function gsm0808_create_cipher2() which takes a struct as
argument instead of individual fields. This is akin to e.g.
gsm0808_create_handover_request() below in the file, and allows
backwards compatibly extending the argument list without needing a new
function signature every time.

Add struct gsm0808_cipher_mode_command, as argument list for
gsm0808_create_cipher2(), with kc128 included.

Encode the Kc128 IE in gsm0808_create_cipher2().

Implement gsm0808_create_cipher() by calling gsm0808_create_cipher2().

Change-Id: Ib3906085e0c6e5a496a9f755f0f786238a86ca34
2021-06-21 00:36:46 +02:00
Eric Wild c3fa007610 kdf: add key derivation functions
generic sha code from git://w1.fi/hostap.git commit
5ea93947ca67ba83529798b806a15b247cdb2e93 which also happens
to be the source of our milenage code.

Related: SYS#5324
Change-Id: Ibf2e49edada944d91ceba62bd0d6b6ce69261fcd
2021-06-08 02:38:15 +02:00
Pau Espin cde47795d1 gsm0808: Introduce gsm0808_old_bss_to_new_bss_info_att_tlvdef
Introduce TLV attribute definition for "Old BSS to New BSS Information"
container.

Related: SYS#5337
Change-Id: I0e55e947b6fef6dad0cf1a6c16b781bef4cc76c5
2021-04-21 19:02:31 +02:00
Neels Hofmeyr a9da9f7640 RR: add VAMOS channel modes
Also add functions to convert between VAMOS and non-VAMOS speech modes.

Related: SYS#4895 SYS#5315
Change-Id: Ie0ea592da5610ae70290106d004e549cf3212a89
2021-04-20 02:42:42 +02:00
Neels Hofmeyr 47c7b4fc24 add osmo_bts_features_names: short BTS feature strings
This will be used by osmo-bts-omldummy to parse features strings from
the cmdline.

Note that osmo_bts_feature_name() already exists to return the longer
descriptive value_strings from osmo_bts_features_descs (_descs!).
Luckily that misses the plural 'features' in the name, so that I can
still add a properly named osmo_bts_features_name() function that only
returns the name, matching the common pattern used in osmocom code.

Related: SYS#4895
Change-Id: I699cd27512887d64d824be680303e70fff3677c1
2021-04-09 00:10:44 +02:00
Pau Espin Pedrol d7a209bce9 gsm: Introduce API osmo_gsm48_rest_octets_si13_decode
Related: SYS#5358
Change-Id: I74fb0a3afc1ac4aadbfc609b882d929401f790eb
2021-02-18 00:54:33 +00:00
Philipp Maier d11a5d5b9a gsm48: add compare function for struct gprs_ra_id
Comparing struct gprs_ra_id using memcmp can be error prone, so lets add
a compare function to compare two struct gprs_ra_id values reliably.

Change-Id: I4d7558c04d9d01761516526086be5104bb2eeada
Related: SYS#5103
2021-02-04 15:17:41 +01:00
Vadim Yanitskiy 943133cad8 gsm_7bit_encode_n(): fix integer overflow in gsm_septets2octets()
Using 'uint8_t' for the length argument is definitely a bad idea.
Because of this, packing more than 255 septets would not work as
expected.  Deprecate the old function and use 'size_t' instead.

Change-Id: Ib1aac538afeb0a5c76a1df472d555139a496e12e
2021-02-01 17:47:54 +00:00
Pau Espin d426ba6730 gsm: Introduce osmo_{rai,cgi_ps}_cmp() APIs
Similar to what we already have for other data types, such as
osmo_lai_cmp or osmo_cgi_cmp.

Change-Id: I00e329bc5be8674b30267dec238e7656ddfc21db
2021-01-22 20:32:45 +01:00
Pau Espin cc885fb0b6 gsm: Add missing osmo_*_cmp symbols to libosmogsm.map
Change-Id: I8ff677aa381118466d065abee7db20b15880352f
2021-01-22 17:44:04 +01:00
Pau Espin ca33a71ca8 Intoduce Packet Switch CGI
This structure is needed in order to identify a given cell within the
BSS during RIM transactions.
The naming was made up by myself since I couldn't find any naming
reference for this kind of data (RAI + CI).
Since LAI + CI = CGI, then RAI + CI = CGI-PS

osmo_rai_name2 family of functions get a "2" suffix due to already
existing functions handling struct struct gprs_ra_id in gsm48.h

Change-Id: If48f412c32e8e5a3e604a78d12b74787a4786374
2021-01-11 14:22:21 +00:00
Harald Welte 9510992c53 Introduce 'osmo_tlv_prot' abstraction for validation of TLV protocols
This extends our existing TLV parser with the ability to
* validate that mandatory IEs of a given message are present
* validate that all present IEs are of required minimum length

Introducing this generic layer will help us to reduce open-coded
imperative verification across virtually all the protocols we
implement, as well as add validation to those protocols where we
don't properly perform related input validation yet.

Change-Id: If1e1d9adfa141ca86001dbd62a6a339f9bf9a912
2020-12-08 12:27:38 +00:00
Philipp Maier e36be56fc8 gsm_04_08: add parser for Mobile Station Classmark 3
3GPP TS 24.008 section 10.5.1.7 describes a Mobile Station Classmark 3
IE, which is encoded as CSN.1 struct. This means that it can not be
parsed by just casting a memory location to a struct pointer, so lets
add a parser to parse the CM3 IE.

This is fixed version of Ic8b2bfd00330235f5bed00771e421588abfaac1f,
which got reverted because it used the keyword "class" as struct member,
which lead into problems with c++ builds. This is now fixed.

Change-Id: Id8732551b33616227609cd6fcf6c3133751a89eb
Related: OS#4796 SYS#5114
2020-11-12 15:55:31 +00:00
Harald Welte c2118940aa Revert "gsm_04_08: add parser for Mobile Station Classmark 3"
This reverts commit a4939dc846,
which caused massive build failures in C++ programs like osmo-pcu
- unsurprisingly, as it calls a struct member "class", which is a
reserved keyword in C++.

Change-Id: Ia43e56385e7b580f492c560aee8ff8b1e8a0e1d8
2020-11-11 23:11:15 +01:00
Philipp Maier a4939dc846 gsm_04_08: add parser for Mobile Station Classmark 3
3GPP TS 24.008 section 10.5.1.7 describes a Mobile Station Classmark 3
IE, which is encoded as CSN.1 struct. This means that it can not be
parsed by just casting a memory location to a struct pointer, so lets
add a parser to parse the CM3 IE.

Change-Id: Ic8b2bfd00330235f5bed00771e421588abfaac1f
Related: OS#4796 SYS#5114
2020-11-10 16:36:54 +01:00
Harald Welte 5e1cd5e411 gsm48_rest_octets: Add parser for SI4 rest octets
Introduces osmo_gsm48_rest_octets_si4_decode()

Change-Id: I9d6ed06731ae15fdcef1a1f397d6ac2b7b1ca980
Related: OS#3075
2020-10-15 08:01:43 +02:00
Pau Espin 86160ace73 gsm: Fix make distcheck with parallel make
Change-Id: I0bab4cfbc82d2b0aa7bd07769000ab8e4968a00b
2020-10-13 08:24:03 +00:00
Neels Hofmeyr 5b214e2847 add BSSMAP coding for Location Services
BSSMAP: add A-interface messages between MSC and BSC:
- Perform Location Request
- Perform Location Response
- Perform Location Abort

Change-Id: I4d7302a4853518916b6b425e710c10568eb2ffe5
2020-10-07 15:37:50 +02:00
Neels Hofmeyr 02de87bd5c add BSSMAP-LE coding for Location Services
BSSMAP-LE: add Lb-interface messages between BSC and SMLC:
- Reset
- Reset Acknowledge
- Perform Location Request, possibly containing BSSLAP TA Layer3
- Perform Location Response
- Perform Location Abort
- Connection Oriented Information containing any BSSLAP APDU

Add encoding and decoding tests.

Change-Id: I271e59b794bafc0a7ae0eabbf58918f6d7df431d
2020-10-07 15:37:50 +02:00
Neels Hofmeyr c6848f4145 add BSSLAP coding for Location Services
BSSLAP: there are APDUs transferred in BSSMAP-LE Connection Oriented
Information messages on Lb between BSC and SMLC.
Add BSSLAP coding for these APDU messages:
- TA Layer3
- TA Request
- TA Response, possibly containing Location Estimate coded in GAD
- Reject
- Reset (for intra-BSS handover during TA Request)
- Abort (for inter-BSS handover)

Add encoding and decoding tests.

Change-Id: I6409c4bcac402dc7626a3afce9081c59cd715fe8
2020-10-07 15:19:43 +02:00
Neels Hofmeyr 086bd33f18 add GAD coding for Location Services
GAD, Universal Geographical Area Description:
- raw coding for all GAD elements.
- SI-units encoding and decoding for Ellipsoid point with uncertainty circle,
  which I presume is the typical "at most N meters away from cell tower located
  at X,Y", which corresponds to the TA positioning currently being implemented.
- other SI-units GAD element encodings are so far not implemented.

Add encoding and decoding tests.

In gsm/protocol/gsm_23_032.h are the raw coding structs as defined in 3GPP TS
23.032.

In gsm/gad.h are structs carrying consistent units based on meters and degrees,
for convenient / less error prone handling of GAD data, and for human readable
representations of the GAD data.

The separation of the two is desirable because OsmoBSC will receive GAD data
from OsmoSMLC on the Lb interface, and pass on this data to the MSC via the A
interface. It is better to pass the GAD data as-is without de/encoding.

Change-Id: I7a9dd805a91b1ebb6353bde0cd169218acbf223c
2020-10-07 11:39:46 +00:00
Vadim Yanitskiy fa6cd88ee5 gsm0808: add gsm0808_create_sapi_reject_cause()
This is basically a successor of gsm0808_create_sapi_reject(), but
instead of hard-coding GSM0808_CAUSE_BSS_NOT_EQUIPPED, it allows
the caller to specify a cause value to be used.  The old function
is now deprecated and should not be used.

Change-Id: Iefe5484d0fa02d5722b628b1dc237d51d3fb1a9b
Related: OS#4728
2020-08-26 18:30:19 +07:00
Harald Welte 1bd726a2e4 gsm0808: Add gsm0808_create_common_id()
This function encodes a GSM 08.08 / 48.008 "Common ID" message.

Change-Id: I353adc1aa72377f7d4b3336d2ff47791fb73d62c
Related: OS#2969
2020-06-21 22:06:56 +02:00
Neels Hofmeyr 83025bf1a6 add osmo_mobile_identity API
Implement better API around 3GPP TS 24.008 Mobile Identity coding.

struct osmo_mobile_identity is a decoded representation of the raw Mobile
Identity, with a string representation as well as dedicated raw uint32_t TMSI.
The aim is to remove all uncertainty about decoded buffer sizes / data types.

I have patches ready for current osmo CNI programs, replacing the Mobile
Identity coding with this new API. Deprecate the old MI API.
osmo-bsc: I71c3b4c65dbfdfa51409e09d4868aea83225338a
osmo-msc: Ic3f969e739654c1e8c387aedeeba5cce07fe2307
osmo-sgsn: I4cacb10bac419633ca0c14f244f9903f7f517b49
Note that some GPRS and SGs related coding is done here in libosmocore and
hence currently remains using the old implementation (see previous version of
this patch: Ic3f969e739654c1e8c387aedeeba5cce07fe2307).

New API functions provide properly size-checking implementations of:
- decoding a raw MI from a bunch of MI octets;
- locating and decoding MI from a full 3GPP TS 24.008 Complete Layer 3 msgb;
- encoding to a buffer;
- encoding to the end of a msgb.

Other than the old gsm48_generate_mid(), omit a TLV tag and length from
encoding. Many callers manually stripped the tag and value after calling
gsm48_generate_mid(). The aim is to leave writing a TL to the caller entirely,
especially since some callers need to use a TvL, i.e. support a variable-size
length of 8 or 16 bit.

New validity checks so far not implemented anywhere else:
- stricter validation of number of digits of IMSI, IMEI, IMEI-SV MI.
- stricter on filler nibbles to be 0xf.
As a result, applications using osmo_mobile_identity will be stricter in
rejecting coding mistakes (some of which we currently have in our test suites,
and which we'll need to fix).

Rationale:

While implementing osmo-bsc's MSC pooling feature in osmo-bsc, this API will be
used to reduce the number of times a Mobile Identity is extracted from a raw
RSL message.

Extracting the Mobile Identity from messages has numerous duplicate
implementations across our code with various levels of specialization.
https://xkcd.com/927/

To name a few:
- libosmocore: gsm48_mi_to_string(), osmo_mi_name_buf()
- osmo-bsc: extract_sub()
- osmo-msc: mm_rx_loc_upd_req(), cm_serv_reuse_conn(), gsm48_rx_mm_serv_req(),
  vlr_proc_acc_req()

We have existing functions to produce a human readable string from a Mobile
Identity, more or less awkward:
- gsm48_mi_to_string() decodes a TMSI as a decimal number. These days we use
  hexadecimal TMSI everywhere.
- osmo_mi_name_buf() decodes the BCD digits from a raw MI every time, so we'd
  need to pass around the raw message bytes. Also, osmo_mi_name_buf() has the
  wrong signature, it should return a length like snprintf().
- osmo-bsc's extract_sub() first uses gsm48_mi_to_string() which encodes the
  raw uint32_t TMSI to a string, and then calls strtoul() via
  tmsi_from_string() to code those back to a raw uint32_t.

Each of the above implementations employ their own size overflow checks, each
invoke osmo_bcd2str() and implement their own TMSI osmo_load32be() handling.
Too much code dup, let's hope that each and every one is correct.

In osmo-bsc, I am now implementing MSC pooling, and need to extract NRI bits
from a TMSI Mobile Identity. Since none of the above functions are general
enough to be re-used, I found myself again copy-pasting Mobile Identity code:
locating the MI in a 24.008 message with proper size checks, decoding MI
octets.

This time I would like it to become a generally re-usable API.

This patch was first merged as Ic3f969e739654c1e8c387aedeeba5cce07fe2307 and
caused test fallout, because it re-implemented old API with the new stricter
decoding. In this patch version, old API remains 1:1 unchanged to avoid such
fallout. Applications will soon switch to the new osmo_mobile_identity API and
become stricter on MI coding when that happens, not implicitly by a new
libosmocore version.

Change-Id: If4f7be606e54cfa1c59084cf169785b1cbda5cf5
2020-06-16 15:17:48 +02:00
Harald Welte a13fb75030 Revert "add osmo_mobile_identity API"
This reverts commit d1ceca9d48, as it
introduces regressions in both osmo-msc and osmo-nitb which have been
causing failing builds for several days now.

Change-Id: I4bd958d0cd2ab4b0c4725e6d114f4404d725fcf7
2020-06-16 09:21:08 +02:00
Neels Hofmeyr d1ceca9d48 add osmo_mobile_identity API
Implement better API around 3GPP TS 24.008 Mobile Identity coding.

struct osmo_mobile_identity is a decoded representation of the raw Mobile
Identity, with a string representation as well as dedicated raw uint32_t TMSI.
The aim is to remove all uncertainty about decoded buffer sizes / data types.

I have patches ready for all osmo programs, completely replacing the Mobile
Identity coding with this new API. Hence deprecate the old MI API.

New API functions provide properly size-checking implementations of:
- decoding a raw MI from a bunch of MI octets;
- locating and decoding MI from a full 3GPP TS 24.008 Complete Layer 3 msgb;
- encoding to a buffer;
- encoding to the end of a msgb.

Other than the old gsm48_generate_mid(), omit a TLV tag and length from
encoding. Many callers manually stripped the tag and value after calling
gsm48_generate_mid(). The aim is to leave writing a TL to the caller entirely,
especially since some callers need to use a TvL, i.e. support a variable-size
length of 8 or 16 bit.

New validity checks so far not implemented anywhere else:
- stricter validation of number of digits of IMSI, IMEI, IMEI-SV MI.
- stricter on filler nibbles to be 0xf.

Rationale:

While implementing osmo-bsc's MSC pooling feature in osmo-bsc, this API will be
used to reduce the number of times a Mobile Identity is extracted from a raw
RSL message.

Extracting the Mobile Identity from messages has numerous duplicate
implementations across our code with various levels of specialization.
https://xkcd.com/927/

To name a few:
- libosmocore: gsm48_mi_to_string(), osmo_mi_name_buf()
- osmo-bsc: extract_sub()
- osmo-msc: mm_rx_loc_upd_req(), cm_serv_reuse_conn(), gsm48_rx_mm_serv_req(),
  vlr_proc_acc_req()

We have existing functions to produce a human readable string from a Mobile
Identity, more or less awkward:
- gsm48_mi_to_string() decodes a TMSI as a decimal number. These days we use
  hexadecimal TMSI everywhere.
- osmo_mi_name_buf() decodes the BCD digits from a raw MI every time, so we'd
  need to pass around the raw message bytes. Also, osmo_mi_name_buf() has the
  wrong signature, it should return a length like snprintf().
- osmo-bsc's extract_sub() first uses gsm48_mi_to_string() which encodes the
  raw uint32_t TMSI to a string, and then calls strtoul() via
  tmsi_from_string() to code those back to a raw uint32_t.

Each of the above implementations employ their own size overflow checks, each
invoke osmo_bcd2str() and implement their own TMSI osmo_load32be() handling.
Too much code dup, let's hope that each and every one is correct.

In osmo-bsc, I am now implementing MSC pooling, and need to extract NRI bits
from a TMSI Mobile Identity. Since none of the above functions are general
enough to be re-used, I found myself again copy-pasting Mobile Identity code:
locating the MI in a 24.008 message with proper size checks, decoding MI
octets.

This time I would like it to become a generally re-usable API.

Change-Id: Ic3f969e739654c1e8c387aedeeba5cce07fe2307
2020-06-12 16:35:26 +02:00
Neels Hofmeyr 7dde1f40a2 add gsm23236: MSC pooling: TMSI and NRI utility functions
These utilities will be used by osmo-bsc to determine the Network Resource
Indicator seen in the TMSI, and (potentially) by osmo-msc to compose a TMSI
with a specific NRI, for osmo-bsc's load balancing between several MSCs.

Add utility functions to:
- extract an NRI value from a TMSI.
- overwrite the NRI value in a TMSI.
- limit an NRI in a (random) TMSI to a given list of ranges.
- add NRI value ranges to a list.
- remove them from a list.
- match NRI value (range) to a list.
- parse NRI values from string, for VTY.
- common VTY functionality of adding/removing NRI values from argv.

Add C tests for the above.

Why we need public API for NRI ranges: In osmo-bsc alone, we need the same NRI
API twice, 1: to manage/list NRI value ranges per-MSC, and 2: to manage/list
NULL-NRI values. If we also consider (potentially) adding NRI support to
osmo-msc, we need the same API twice again there. Hence it is useful to define
re-used API up here in libosmocore.

Related: OS#3682
Change-Id: Icb57a2dd9323c7ea11b34003eccc7e68a0247bf5
2020-06-10 14:20:49 +02:00