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From "William A. Rowe, Jr." <wr...@rowe-clan.net>
Subject Re: [PATCH] PR37145: data loss with httpd-2.0.55 reverse proxy method=post
Date Wed, 19 Oct 2005 20:44:22 GMT
Ruediger Pluem wrote:
> 
> On 10/19/2005 08:25 PM, William A. Rowe, Jr. wrote:
> 
> [..cut..]
> 
> 
>>Ruediger - I'm questioning if it's the BRIGADE_CONCAT, or actually if we
>>are
>>failing to respect transient buckets in the core / ssl filters.  If we are
>>failing to pay attention to transient buckets (or not allocating the
>>buckets
>>as transient when, in fact, they are) then this might be the root bug.
> 
> 
> Agreed. The question is what we can expect from the core / ssl filters (Is
> there any kind of contract defined?). This defines if it is a bug in
> core / ssl or in the proxy code.
> So I guess the solution is either to handle transient buckets carefully later by setting
> them aside in this situation, as the current patches do or to adjust the
> core / ssl filters in a way that they do not deliver transient buckets any longer.
> The attached quick and dirty patch following this way seems to solve the problem too,
> but
> 
> - I am not sure about its sideeffects.
> - There are further places in the SSL code where transient buckets get used. They
>   would need to checked as well.

The problem is -not- in creating the transient buckets (if they are sent, that's
goodness).  The problem is in transforming them to persistant buckets before the
core, ssl, or other filters who have set-aside operations decide to return.  So
there should have been no trouble creating the transient bucket below, the
trouble came in when the core filter didn't send the data, and also didn't set
it aside :-(

Bill

> BTW: The problem does not happen without SSL because in this case we get heap buckets
> (checked with gdb, but not in the code).
> 
> Index: modules/ssl/ssl_engine_io.c
> ===================================================================
> --- modules/ssl/ssl_engine_io.c	(Revision 326481)
> +++ modules/ssl/ssl_engine_io.c	(Arbeitskopie)
> @@ -1324,7 +1324,7 @@
>      /* Create a transient bucket out of the decrypted data. */
>      if (len > 0) {
>          apr_bucket *bucket =
> -            apr_bucket_transient_create(inctx->buffer, len, f->c->bucket_alloc);
> +            apr_bucket_heap_create(inctx->buffer, len, NULL, f->c->bucket_alloc);
>          APR_BRIGADE_INSERT_TAIL(bb, bucket);
>      }


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