ucb: webdav-curl: tdf#102499 (2): Refactor the WebDAV resource access retry

[ port of commit ac060f97cc937787b4079e435c5b312f6894c277 ]

Change-Id: Ib8cb79ddc67a486b067d3187a965ac55ae698fa4
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/123492
Tested-by: Michael Stahl <michael.stahl@allotropia.de>
Reviewed-by: Michael Stahl <michael.stahl@allotropia.de>

2 files changed, 29 insertions, 17 deletions

diff --git a/ucb/source/ucp/webdav-curl/DAVException.hxx b/ucb/source/ucp/webdav-curl/DAVException.hxx
index ba121efa21c9..4da64420cc00 100644
--- a/ucb/source/ucp/webdav-curl/DAVException.hxx
+++ b/ucb/source/ucp/webdav-curl/DAVException.hxx
@@ -81,14 +81,14 @@ const sal_uInt16 SC_UNPROCESSABLE_ENTITY             = 422;
 const sal_uInt16 SC_LOCKED                           = 423;
 const sal_uInt16 SC_FAILED_DEPENDENCY                = 424;
 
-//5xx (Server error)
+//5xx (Server error, general <https://tools.ietf.org/html/rfc7231#section-6.6>)
 const sal_uInt16 SC_INTERNAL_SERVER_ERROR            = 500;
 const sal_uInt16 SC_NOT_IMPLEMENTED                  = 501;
 const sal_uInt16 SC_BAD_GATEWAY                      = 502;
 const sal_uInt16 SC_SERVICE_UNAVAILABLE              = 503;
 const sal_uInt16 SC_GATEWAY_TIMEOUT                  = 504;
 const sal_uInt16 SC_HTTP_VERSION_NOT_SUPPORTED       = 505;
-// DAV extensions
+// DAV extensions (<https://tools.ietf.org/html/rfc4918#section-11>)
 const sal_uInt16 SC_INSUFFICIENT_STORAGE             = 507;
 
 
diff --git a/ucb/source/ucp/webdav-curl/DAVResourceAccess.cxx b/ucb/source/ucp/webdav-curl/DAVResourceAccess.cxx
index cead9980b4a6..e76e6ae9d1fa 100644
--- a/ucb/source/ucp/webdav-curl/DAVResourceAccess.cxx
+++ b/ucb/source/ucp/webdav-curl/DAVResourceAccess.cxx
@@ -1045,7 +1045,7 @@ void DAVResourceAccess::initialize()
                 return;
         }
 
-        // Own URI is needed for redirect cycle detection.
+        // Own URI is needed to redirect cycle detection.
         m_aRedirectURIs.push_back( aURI );
 
         // Success.
@@ -1147,23 +1147,35 @@ bool DAVResourceAccess::handleException(DAVException const& e, int const errorCo
             return true;
         }
         return false;
-    // --> tkr #67048# copy & paste images doesn't display.
-    // if we have a bad connection try again. Up to three times.
+        // i#67048 copy & paste images doesn't display. This bug refers
+        // to an old OOo problem about getting resources from sites with a bad connection.
+        // If we have a bad connection try again. Up to three times.
     case DAVException::DAV_HTTP_ERROR:
-        // retry up to three times, if not a client-side error.
-        // exception: error 501, server side error that
-        // tells us the used method is not implemented
-        // on the server, it's nonsense to insist...
-        if ( ( e.getStatus() < 400 || e.getStatus() >= 500 ||
-               e.getStatus() == 413 ) &&
-             ( e.getStatus() != 501 ) &&
-             errorCount < 3 )
-        {
+        // retry up to three times, if not a client-side error (4xx error codes)
+        if ( e.getStatus() < SC_BAD_REQUEST && errorCount < 3 )
             return true;
+        // check the server side errors
+        switch( e.getStatus() )
+        {
+            // the HTTP server side response status codes that can be retried
+            // [Serf TODO? i#119036] case SC_REQUEST_ENTITY_TOO_LARGE:
+            case SC_BAD_GATEWAY:        // retry, can be an excessive load
+            case SC_GATEWAY_TIMEOUT:    // retry, may be we get lucky
+            case SC_SERVICE_UNAVAILABLE: // retry, the service may become available
+            case SC_INSUFFICIENT_STORAGE: // space may be freed, retry
+            {
+                if ( errorCount < 3 )
+                    return true;
+                else
+                    return false;
+            }
+            break;
+            // all the other HTTP server response status codes are NOT retry
+            default:
+                return false;
         }
-        return false;
-    // <--
-    // --> tkr: if connection has said retry then retry!
+        break;
+    // if connection has said retry then retry!
     case DAVException::DAV_HTTP_RETRY:
         return true;
     // <--