[jira] [Assigned] (PROTON-1837) [c] client generates invalid attach/detach sequence

["Alan Conway (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PROTON-1837?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alan Conway reassigned PROTON-1837:
-----------------------------------

    Assignee:     (was: Alan Conway)

> [c] client generates invalid attach/detach sequence
> ---------------------------------------------------
>
>                 Key: PROTON-1837
>                 URL: https://issues.apache.org/jira/browse/PROTON-1837
>             Project: Qpid Proton
>          Issue Type: Bug
>          Components: proton-c
>    Affects Versions: proton-c-0.22.0
>            Reporter: Alan Conway
>            Priority: Minor
>
> There is a disabled test to reproduce this problem, see test_duplicate_link_client() in
> [https://github.com/alanconway/qpid-proton/blob/master/c/tests/connection_driver.c#L498]
> pni_process does all pending link opens before all pending link closes, it does not respect the order of individual open/close calls in the code. This doesn't cause a problem for distinct links but if a link of the same name is opened/closed/reopened very quickly it can cause a problem:
> For example if l1 and l2 are both pn_links with name "x" then this sequence:
> {code:java}
> open(l1); close(l1); open(l2){code}
> generates this illegal protocol sequence:
> {code:java}
> attach("x"); attach("x"); detach(0) // 0 is the handle assigned to "x"{code}
> instead of the intended legal sequence:
> {code:java}
> attach("x"); detach(0); attach("x") // detach(0) detaches the first "x" so second "x" is allowed{code}
> NOTE: This applies to all endpoints, not just links but since connections and sessions don't have client-assignable names that can clash, the problem only shows up for links and only if the detach/attach for the same name is processed in the same transport batch. This is unlikely in practice and was discovered only because of investigation of PROTON-1832.



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