Re: #1416

In <[email protected]> Russ Allbery <[email protected]> writes:

>[email protected] writes:

>> I don't think I understand the issue, because I don't see the reason for
>> the exemption of "has date and message id" from insertion of Injection
>> Date.

>Briefly: the Message-ID plus the Date is the unique identifier for the
>message.  If you allow an injecting agent to change one or the other (and
>adding an Injection-Date is effectively changing the Date), you break
>uniqueness.  This creates the possibility of duplicates.

Which is, of course, why we REQUIRE people doing multiple injections to
insert all these things themselves before injecting any of them.

>In this case, the scenario under which duplicates arise is possible but
>unlikely.  It requires, if I remember correctly, badly-timed multiple
>injection of the message such that it expires on the basis of its original
>Date and is then reaccepted on the basis of the modified Injection-Date.

It requires the badly timed events to cause arrival at some site within the
critical 24 hours mentioned in the text, having failed to flood around the
site that introduced the delay. Moreover, the duplicate copies that a user
at that site sees will only differ in the presence of an Injection-Date in
the one, but not in the other. The full scenario is explained in
http://www.imc.org/ietf-usefor/drafts/issue-1416.

>> Isn't the benefit of the Injection-Date header available to any server
>> that is updated to read it, regardless of any other transport server?

>Assuming that the message ever gets to you, yes.  However, unless enough
>other servers implement Injection-Date to allow flood-fill to reach you, a
>message that benefits from this feature won't get to you for you to be
>able to benefit.

The benefit of Injection-Date is that a badly delayed article is more
likely to reach you, assuming you and your upstreams have taken advantage
of it, of course. I think you are more likely to get that benefit if the
disputed sentence is omitted.

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