Both csnStreamDecoder() and csnStreamEncoder() shall not return 0
prematurely if no more bits left in the input / output bit-vector.
Returning CSN_ERROR_NEED_MORE_BITS_TO_UNPACK might make more sense,
however we don't know in advance (i.e. without entering the loop)
whether it's an error or not. Some CSN.1 definitions have names
like 'M_*_OR_NULL', what basically means that they're optional
and can be ignored or omitted.
Most of the case statements do check whether the number of remaining
bits is enough to unpack / pack a value, so let's leave it up to
the current CSN_* handler (pointed by pDescr) if no bits left.
Return CSN_ERROR_NEED_MORE_BITS_TO_UNPACK only if the number of
remaining bits is negative as this is an error in any case.
Change-Id: Ie3a15e210624599e39b1e70c8d34efc10c552f6c
Port from wireshark.git de028e81c53f9c45ccc5adb3bffd2f16ae2017bf
This commit breaks transcoding of the test vectors containing
the MS RA Capability IE due to the reasons explained in [1].
The more fields we add, the longer gets the output of the CSN.1
encoder. This is not critical, since we never need to encode
messages containing the MS RA Capability IE on practice.
[1] Ibb4cbd3f5865415fd547e95fc24ff31df1aed4c0
Ported-by: Pau Espin Pedrol <pespin@sysmocom.de>
Change-Id: Ibb4cbd3f5865415fd547e95fc24ff31df1aed4c0
This change fixes a bug that was reported by Keith Whyte and
confirmed in [1]. The problem is that a user-defined handler
in case of CSN_SERIALIZE may parse only a part of the given
bit-stream, leaving some bits unhandled. This is expected
because the sender (i.e. the MS) may use more recent RLC/MAC
message definitions containing new fields at the end.
Those bits that were left unhandled by serialize() shall not be
interpreted as continuation of the message, they shall be skipped.
Note that the encoded vector in the RLCMAC unit test still does
not match the original one. That's a known bug explained in [2].
[1] If5873355d52d7ddb06c2716154a88d34100f6ab5
[2] Ic46d6e56768f516203d27d8e7a5adb77afdf32b7
Change-Id: Id4cc042fed68fc54aca0355dcb986cab3f6b49ea
Related: OS#4338
This test vector (from HTC Desire 628) demonstrates a bug in the
CSN.1 decoder. For some reason, OsmoPCU fails to decode it:
DCSN1 ERROR csnStreamDecoder: error NEED_MORE BITS TO UNPACK (-5)
at EGPRS_TimeslotLinkQualityMeasurements (idx 164)
while Wireshark dissects it without any errors.
Change-Id: If5873355d52d7ddb06c2716154a88d34100f6ab5
Reported: https://osmocom.org/issues/4338#note-15
Related: OS#4338
The main idea of this change is to demonstrate a weakness of the
CSN.1 codec that most likely causes a unit test breakage in [1].
The problem seems to be that the transitional structures, where
the CSN.1 decoder stores the results, do not contain any details
about presence of the optional fields (such as M_UINT_OR_NULL).
In other words, it's impossible to know whether some optional
field is omitted in the encoded message (NULL), or is it just
set to 0. This means that the encoder will always include all
optional fields, even if they're not present in the original
message.
[1] Ibb4cbd3f5865415fd547e95fc24ff31df1aed4c0
Change-Id: Ic46d6e56768f516203d27d8e7a5adb77afdf32b7
Long story short: as it turns out the test vector '12a5146200'O
has been generated by TITAN, and it's malformed. The length
indicator it contains must be at least 29 bits, not 21. This
field is calculated by TITAN automatically, so I guess there
is a bug somewhere in its RAW encoder implementation.
It's funny that Wireshark decodes the old malformed vector without
any problems if it's encapsulated into the BSSGP DL-UNITDATA. The
reason for that is because BSSGP dissector does not actually use
the CSN.1 codec and relies on its own hand-written parser [1],
which does not respect the length constraints.
Furthermore, table 10.5.146/3GPP TS 24.008, describing the format
of MS Radio Access Capability IE, has the following comment:
< Multislot capability struct > ::=
{ 0 | 1 < HSCSD multislot class : bit (5) > }
...
-- error: struct too short, assume features do not exist
so ideally our CSN.1 decoder should be more tolerant to the old
malformed vector, but unfortunately error handling is not implemented.
[1] See de_gmm_ms_radio_acc_cap() in epan/dissectors/packet-gsm_a_gm.c.
Change-Id: I5f810397b8d09c18e069168023429f6a4d899c86
The implementation of CSN.1 codec was taken from Wireshark, where
it's implemented in pure C. For some reason it was mixed with C++
specific features, mostly using references in parameter
declaration. Not sure what are the benefits.
Change-Id: I56d8b7fbd2f9f4e0bdd6b09d0366fe7eb7aa327a
This would allow us to catch more bugs. Note that I had to remove
printing of pointer address to make the output deterministic.
Change-Id: I1a77441eb957353c919bc73f8e3a2e38f4a383a9
It contails no valid identity, and thus violates the specs.
Let's keep it 'as-is' to check that decoder actually fails.
Change-Id: I663edfdaac0c065e08ab7b6dc50d2f18e433433c
Related: OS#4392
After the recent changes [1], it was noticed that one of the unit
tests fails. In particular, a decode-encode cycle of Packet
Polling Request produces a different vector:
vector1 = 49 13 e0 08 50 88 40 13 a8 04 8b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
vector2 = 49 13 01 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b 2b
vector1 == vector2 : FALSE
As it turns out, the original (input) vector itself is malformed
because it contails no valid identity, and thus violates the
specs. The CSN.1 decoder from Pycrate [2] throws an exception
while trying to decode it. I believe we should do the same.
Let's stop decoding the bit stream and return an error in case
if neither of a given list of the choice items matched.
[1] Ia0f8cc224a4c38e80699f834fd83d4c0d99322ea
[2] https://github.com/P1sec/pycrate
Change-Id: I420144773ed5e80372534e0f18db5e74cdb2999d
Fixes: OS#4392
(as they are part of the RlcMacUplink_t structure that is also used to call csnStreamDissector function).
Port from wireshark.git commit 9f8b638cfa8a660fb64c54dcadb83e6747db0a15.
Ported-by: Pau Espin Pedrol <pespin@sysmocom.de>
Change-Id: If46f8cc3f21f527f911dcac6ff1b78f182104a00
Currently code using that function in osmo-pcu is disabled, allegadly
because SGSN was sending incorrect values, but it looks more like a CSN1
issue.
Related: OS#1525, OS#3499
Change-Id: I92c86397f988afaa791871d823a45fa85054f3bb
Current stderr output is empty anyway, and not checking it allows
enavling different log levels to easily debug issues.
Change-Id: I5b12e919e08a6eeaad31a459e5a15fdee4d76a61
Old method takes lots of lines of codes and prints inn unconfortable way
because left-trailing zeros are dropped, making it difficult to split in
bytes.
Change-Id: I56c24f934824e4e52a91a7273aec384b2e15aa67
There is a duality of initialization: early_init() in bts.cpp wants to init
logging even before static instances get initialized. Make sure that
tall_pcu_ctx is initialized during early_init() as well. There is a build
context that does not seem to include bts.cpp (osmo-pcu-remote), so to be sure,
init tall_pcu_ctx as NULL and both in early_init() as well as pcu_main.cpp,
init both tall_pcu_ctx and logging if it is still NULL.
Change-Id: I2199b62d0270bd35dec2283e8f5b364b7c63915b
Fix attempted read past vector boundaries in case of a starting bit offset !=
0, so that the last amount of bits read should be < 8. In the case of
CSN_LEFT_ALIGNED_VAR_BMP, the mod-8 calculation was flawed, and in the final
step, 8 bits were read instead of the remainder < 8. This lead to -EINVAL being
returned by bitvec_get_bit_pos() and bogus resulting data.
Instead, read 8 bits only as long as at least 8 bits remain, and read any
remaining bits < 8 in a final step. Drop unneeded nB1 variable and an obvious
comment.
Adjust the unit test assertion in testCsnLeftAlignedVarBmpBounds() in
RLCMACTest.cpp.
Based on a fix by Aravind Sirsikar <Arvind.Sirsikar@radisys.com>, but
implemented differently.
Related: OS#1805
Change-Id: I490498c8da6b531f54acb673379379f7b10907c0
CSN1 decoding currently contains an attempted read past vector boundaries in
case of a starting bit offset != 0, so that the last amount of bits read should
be < 8. In the case of CSN_LEFT_ALIGNED_VAR_BMP, the mod-8 calculation is
flawed, and in what should be the final step of reading n < 8 bits, 8 bits are
read instead of n (with an extraneous read of n bits following after that).
This leads to -EINVAL being returned by bitvec_get_bit_pos() and bogus
resulting data.
Add testCsnLeftAlignedVarBmpBounds() in RLCMACTest.cpp to show and expect this
bug. The test's expectation shall be corrected along with the bug fix in a
subsequent commit.
Related: OS#1805
Tweaked-by: Neels Hofmeyr <nhofmeyr@sysmocom.de>
Change-Id: I4641f5d1d49f66cb1a5cd813befb3a2a266001b0
The remaining_bits_len is correctly decremented while encoding
CSN_RECURSIVE_ARRAY for fixing the bug.
Details of the bug is in https://projects.osmocom.org/issues/1641
During introduction of basic EGPRS feature new hex dump message
PUASS, from a different working network log was used in Unit test.
It exposed the issue of incorrect handling of recursive array
encoding in osmo-pcu.
Fixes: OS#1641
This patch is for fixing encoding of padding bits according to the
3gpp spec 44.060 section 11, wherein it shall always start with 0
bit followed with spare padding bits.
During introduction of basic EGPRS feature new hex dump messages
from a different working network log were used in Unit test. These
exposed the issue of incorrect handling of padding bits encoding
in osmo-pcu.
Corrections in the existing test vector of rlcmac is also updated.
In testsuite tbf appropriate corrections for the Tbftest.err is
also done.
As a last minute change I probably ran git rebase --whitespace=fix
on the patch set and broke the test result. Update the expected
file and tests should pass.