OsmoBSC ASSIGNMENT FAIL doesn't contain useful cause
bssmap_handle_assignm_req() will currently only return one cause value no matter what the error: GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLEThis is incorrect, as
- in case of missing mandatory information elements we should rather use GSM0808_CAUSE_INFORMATION_ELEMENT_OR_FIELD_MISSING
- in case of decoding errors something like GSM0808_CAUSE_INVALID_MESSAGE_CONTENTS
- in case of unsupported (e.g. mode) something like GSM0808_CAUSE_REQ_CODEC_TYPE_OR_CONFIG_UNAVAIL
We also need to analyze how the functions that are called by bssmap_handle_assignm_req() can fail and make them return according to the exact nature of their failure.