[metrics-bugs] #21934 [Metrics/metrics-lib]: Allow extra arguments in lines containing comma-separated key-value lists

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#21934: Allow extra arguments in lines containing comma-separated key-value lists
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 Reporter:  karsten              |          Owner:  metrics-team
     Type:  defect               |         Status:  new
 Priority:  Medium               |      Milestone:
Component:  Metrics/metrics-lib  |        Version:
 Severity:  Normal               |     Resolution:
 Keywords:                       |  Actual Points:
Parent ID:                       |         Points:
 Reviewer:                       |        Sponsor:
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Comment (by iwakeh):

 [https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n923 dir-
 spec] defines the field `dirreq-v3-resp` more narrowly (the 'nul' there
 should be 'num'):
 {{{
     "dirreq-v3-resp" status=nul,... NL
         [At most once.]
 }}}

 Which I would take to mean only status-types are allowed on the left of
 equal and a number to the right, but of these an arbitrary number.  But,
 response statuses can be added any time, so the patch above seems to do
 the right thing.  The further parsing doesn't verify the status strings,
 which is correct for 'dirreq-v3-resp'.

 There seems to be an ambiguity in defining these things, for
 [https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n1058
 example]:
 {{{
 "cell-circuits-per-decile" num NL
         [At most once.]
 }}}

 In this case only a single value makes sense, but other than not using the
 dots it is not expressed clearly in dir-spec.  Could a value be added
 (e.g. the median) here without changing the protocol?

 In order to check for all fields it might be necessary to go through all
 fields one by one and check.

 What comes to mind is using a grammar for checking the spec definitions.
 Were there reasons once upon a time not to use a grammar and automated
 checking for the spec?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21934#comment:1>
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