UPF could crash when handling PFCP Session Establishment/Update
containing a CreateURR with a malformed Dropped-DL-Traffic-Threshold IE.
Added length validation for Dropped-DL-Traffic-Threshold and
Volume Measurement IEs to prevent buffer misuse and return an
appropriate PFCP cause and offending IE value.
Also removed assertion in IE parsing functions and replaced it with
error logging and validation checks.
Issues: #4154, #4152
Add explicit length checks for Maximum Bitrate and Guaranteed Bitrate
IEs in Create/Update QER handlers. When the IE length does not match
OGS_PFCP_BITRATE_LEN, return INVALID_LENGTH with the corresponding
offending IE type.
Also update ogs_pfcp_parse_bitrate() to log a detailed error message
and return 0 when the encoded IE length is invalid, instead of asserting.
This prevents crashes caused by malformed PFCP messages and ensures
correct cause/offending IE reporting to the peer.
Issues: #4152
When converting bitrates from bits per second to kilobits per second,
if the conversion results in fractions, the resulting value should be
rounded upwards
When connecting to the UPF port for the PFCP protocol (8805) and sending
an association setup request followed by a session establishment request
with a PDI Network Instance set to ‘internet’, it causes a stack corruption
to occur.
So, ogs_fqdn_parse() fixed.
