Attachment 159997 Details for Bug 132460 – Fix feedback-loop during WebDAV lock refresh

[patch] Fix feedback-loop during WebDAV lock refresh

fix-webdav-feedback-loop.patch (text/plain), 3.00 KB, created by Jean-Louis Fuchs on 2020-04-27 14:23:53 UTC

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Creator: Jean-Louis Fuchs

Created: 2020-04-27 14:23:53 UTC

Size: 3.00 KB

patch

obsolete

>commit 904b2836b3914696f610789ddd87a1c0f80cc0e7
>Author: Jean-Louis Fuchs <jean-louis.fuchs@adfinis-sygroup.ch>
>Date:   Fri Mar 27 17:27:51 2020 +0100
>
>    Fix feedback-loop during WebDAV lock refresh
>    
>    Prevent a feedback-loop, where LibreOffice would request a shorter timeout on
>    each refresh.
>    
>    WebDAV servers do not return the lock-timeout the lock was set up with; they
>    have to return the remaining time. There are WebDAV servers that return a lower
>    timeout. Two examples [2] [3]. Other servers probably reuse the same timestamp
>    for the whole request and are therefore not subject to that problem. (This might
>    even be incorrect if the request takes very long.)
>    
>    Updating the lock-timeout with the value returned by the server decreases the
>    timeout until it reaches zero.
>    
>    LibreOffice request               SERVER response
>    LOCK(180)         ->              LOCK(60)
>    LOCK(60)          ->              LOCK(59)
>    LOCK(59)          ->              LOCK(58)
>    ...
>    0: no LOCK header ->              FAIL
>    
>    If we do not update the timeout in NeonSession::LOCK() only the initial setup
>    updates the timeout.
>    
>    LibreOffice request               SERVER response
>    LOCK(180)        ->               LOCK(60)
>    LOCK(60)         ->               LOCK(59)
>    LOCK(60)         ->               LOCK(59)
>    ...
>    
>    It is essential that lastChanceToSendRefreshRequest uses the timeout returned by
>    the server; after it calculated the deadline, we reset the timeout.
>    
>    The maintainer of neon confirmed that the timeout should stay the same after the
>    initial setup. [4].
>    
>    [1] https://tools.ietf.org/html/rfc4918#section-6.6
>    [2] https://www.alfresco.com/
>    [3] https://github.com/mar10/wsgidav
>    [4] https://github.com/notroj/neon/issues/12
>
>diff --git a/ucb/source/ucp/webdav-neon/NeonSession.cxx b/ucb/source/ucp/webdav-neon/NeonSession.cxx
>index c178c1e90238..a1570465617b 100644
>--- a/ucb/source/ucp/webdav-neon/NeonSession.cxx
>+++ b/ucb/source/ucp/webdav-neon/NeonSession.cxx
>@@ -1624,6 +1624,10 @@ bool NeonSession::LOCK( NeonLock * pLock,
>     TimeValue startCall;
>     osl_getSystemTime( &startCall );
> 
>+    // save the current requested timeout, because ne_lock_refresh uses
>+    // pLock->timeout as an out parameter. This prevents a feedback-loop,
>+    // where we would request a shorter timeout on each refresh.
>+    long timeout = pLock->timeout;
>     const int theRetVal = ne_lock_refresh(m_pHttpSession, pLock);
>     if (theRetVal == NE_OK)
>     {
>@@ -1631,7 +1635,6 @@ bool NeonSession::LOCK( NeonLock * pLock,
>             = lastChanceToSendRefreshRequest( startCall, pLock->timeout );
> 
>         SAL_INFO( "ucb.ucp.webdav", "LOCK (refresh) - Lock successfully refreshed." );
>-        return true;
>     }
>     else
>     {
>@@ -1648,6 +1651,8 @@ bool NeonSession::LOCK( NeonLock * pLock,
>         }
>         return false;
>     }
>+    pLock->timeout = timeout;
>+    return lock_result;
> }
> 
> void NeonSession::UNLOCK( const OUString & inPath,

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Attachments on bug 132460: 159997