Acct-Delay-Time missing with RADIUS accounting

[Nick Lowe]

There ought to be consideration of getting the Acct-Delay-Time
attribute included in hostapd's RADIUS accounting.

https://tools.ietf.org/html/rfc2866#section-5.2

The justification for this would be to accommodate:

1) RADIUS accounting consumers that do not support the Event-Timestamp
attribute but do support the Acct-Delay-Time attribute.

2) To account reliably where the system clock is close to the UNIX
time epoch and the Event-Timestamp attribute cannot be included. This
is, of course, usually where NTP sync has not occurred.

This is complicated by the fact that when the attributes of any RADIUS
accounting packet change, the identifier associated with the packet
must be changed as well. This applies to the Acct-Delay-Time attribute
specifically, when the delay time is changed, a new identifier must be
generated packet.

Is this something that you may be prepared to look at, Jouni?

The initial packet sent should contain this attribute wth a value of
0. Retries, the difference between the initial send and the time of
the retransmission, using a monotonic timer to calculate this.

Cheers,

Nick