[Varnish] #1420: Ban/Fetch race

[Varnish]

#1420: Ban/Fetch race
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 Reporter:  phk       |      Owner:  phk
     Type:  defect    |     Status:  new
 Priority:  normal    |  Milestone:
Component:  varnishd  |    Version:  trunk
 Severity:  normal    |   Keywords:
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 There exists a race between fetch and bans today:

 Fetch starts, but takes long time.
 Ban is entered which applies to fetch

 Once we get the headers from the backend, we currently do not check if any
 bans were entered between the fetch starting and now, which might apply.

 What to do in that case is also slightly icky.  Turning the fetch into a
 pass has been proposed as a least-evil handling.

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Ticket URL: <https://www.varnish-cache.org/trac/ticket/1420>
Varnish <https://varnish-cache.org/>
The Varnish HTTP Accelerator