[tahoe-lafs-trac-stream] [tahoe-lafs] #1993: Abuse of HTTP status 410 Gone

[tahoe-lafs]

#1993: Abuse of HTTP status 410 Gone
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 Reporter:  kpreid             |          Owner:
     Type:  defect             |         Status:  new
 Priority:  normal             |      Milestone:  undecided
Component:  code-frontend-web  |        Version:  1.10.0
 Keywords:  http               |  Launchpad Bug:
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 !NotEnoughSharesError, !NoSharesError, and !UnrecoverableFileError, at
 least, are being reported using HTTP status code 410 Gone, which is a
 severe misuse of the code, as 410 means that the resource is '''known to
 be''' forevermore unavailable. Per RFC 2616 section 10.4.11:

     The requested resource is no longer available at the server and no
 forwarding address is known. This condition is expected to be considered
 permanent. Clients with link editing capabilities SHOULD delete references
 to the Request-URI after user approval. If the server does not know, or
 has no facility to determine, whether or not the condition is permanent,
 the status code 404 (Not Found) SHOULD be used instead.

 All of these errors indicate that the gateway is ''currently'' unable to
 fulfill the request (as any of them could result from temporary partition
 in the grid), not permanent deletion. 410 would be appropriate if, for
 example, a mutable file were put into a revoked, “no content and cannot be
 written to further”, state, but not for anything less drastic. (Tahoe is
 unusual in having even the architectural possibility of having enough
 confidence to correctly answer 410!)

 The most appropriate response codes would be, I think, 404 for
 !NoSharesError (because the grid has no knowledge of the file) and 503 for
 !NotEnoughSharesError (because the grid knows the file exists but cannot
 be served). !UnrecoverableFileError appears to be a conflation of the two
 in the case of mutable files, and so I see no good answer there but to
 introduce a distinction between the two cases.

 Regardless, 410 should not be used in any of these cases.

 I noticed this via https://tahoe-lafs.org/pipermail/tahoe-
 dev/2013-May/008313.html .

-- 
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1993>
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