tree c6f2e1dbe547a996fcaac372d168cd4f33b3fa19
parent c2f1ed1dd098ea2fe3e285ed8fe15a06b0a5f01a
author Vadim Yanitskiy <vyanitskiy@sysmocom.de> 1670952239 +0700
committer Vadim Yanitskiy <vyanitskiy@sysmocom.de> 1670963091 +0700

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