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From "Nathan Campbell (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PROTON-1661) Incomplete name comparision in transport.c pn_find_link()
Date Mon, 30 Oct 2017 14:53:01 GMT

    [ https://issues.apache.org/jira/browse/PROTON-1661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16225063#comment-16225063
] 

Nathan Campbell commented on PROTON-1661:
-----------------------------------------

Moving to a newer version (newer then 0.17) isn't possible for various reasons.  I already
fixed it and it's working for us, would you guys rather I make a merge request for older versions
of proton-c?  This is a particularly nasty bug that hangs the client inside of session.createReceiver()
(at least for qpid-cpp-1.36) forever and was challenging to debug.  There are probably others
using older versions of proton-c, based on git blame this bug is 4 years old!  Let me know.

> Incomplete name comparision in transport.c pn_find_link()
> ---------------------------------------------------------
>
>                 Key: PROTON-1661
>                 URL: https://issues.apache.org/jira/browse/PROTON-1661
>             Project: Qpid Proton
>          Issue Type: Bug
>          Components: proton-c
>    Affects Versions: 0.11.1, proton-c-0.17.0
>         Environment: RedHat EL 5 & 7
>            Reporter: Nathan Campbell
>
> Tested in both proton-c version 0.11.1 and 0.17.0 with qpid broker 1.36.0
> Problem:
> Function "pn_find_link()" incorrectly returns a link when argument "name" matches first
N characters of existing link.
> i.e.:
> 1) QPID client creates receiver with address "amq.topic/fooBar":
>    Broker will call function pn_find_link( ssn, name = "fooBar", true) which returns
NULL as expected.  Link is initialized and receiver works as expected.
> 2) Some time later the same QPID client creates second receiver with address "amq.topic/foo":
>   Broker will call function pn_find_link( ssn, name="foo", true) which incorrectly returns
pointer to existing link.  Expected behavior is to return NULL so that link will (later) be
initialized.
> This is because if() starting on line 1268 of proton-c/src/core/transport.c only uses
strncmp().
> eg: "strncmp( "foo", "fooBar", 3) == 0"
> That if() also needs to check +sizes of the names+ and only do "strncmp()" if:
> "(name.size == strlen(pn_string_get(link->name)))"
> Symptoms:
> Qpid client blocks indefinitely on second ConnectionContext::createReceiver() waiting
for link to be established.  Broker never does PN_LINK_INIT because it incorrectly believes
link already exists, client is hung waiting for message back from broker.



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