Defines an interface representing the Failed-AVP grouped AVP type.
From the Diameter Base Protocol (rfc6733.txt) specification:
7.5. Failed-AVP AVP
The Failed-AVP AVP (AVP Code 279) is of type Grouped and provides
debugging information in cases where a request is rejected or not
fully processed due to erroneous information in a specific AVP. The
value of the Result-Code AVP will provide information on the reason
for the Failed-AVP AVP. A Diameter answer message SHOULD contain an
instance of the Failed-AVP AVP that corresponds to the error
indicated by the Result-Code AVP. For practical purposes, this
Failed-AVP would typically refer to the first AVP processing error
that a Diameter node encounters.
The possible reasons for this AVP are the presence of an improperly
constructed AVP, an unsupported or unrecognized AVP, an invalid AVP
value, the omission of a required AVP, the presence of an explicitly
excluded AVP (see tables in Section 10) or the presence of two or
more occurrences of an AVP that is restricted to 0, 1, or 0-1
occurrences.
A Diameter message SHOULD contain one Failed-AVP AVP, containing the
entire AVP that could not be processed successfully. If the failure
reason is omission of a required AVP, an AVP with the missing AVP
code, the missing Vendor-Id, and a zero-filled payload of the minimum
required length for the omitted AVP will be added. If the failure
reason is an invalid AVP length where the reported length is less
than the minimum AVP header length or greater than the reported
message length, a copy of the offending AVP header and a zero-filled
payload of the minimum required length SHOULD be added.
In the case where the offending AVP is embedded within a Grouped AVP,
the Failed-AVP MAY contain the grouped AVP, which in turn contains
the single offending AVP. The same method MAY be employed if the
grouped AVP itself is embedded in yet another grouped AVP and so on.
In this case, the Failed-AVP MAY contain the grouped AVP hierarchy up
to the single offending AVP. This enables the recipient to detect
the location of the offending AVP when embedded in a group.
AVP Format
<Failed-AVP> ::= < AVP Header: 279 >
1* {AVP}