Reverse Proxy and an External Filter

[Mark Zetts <zetts@xxxxxxxxxx>]

  Running Apache 2.2.4 on Windows
2003 server, I have two problems with an external filter written in C.
 The Apache server is running as a reverse proxy.  

   1)  The filter is
often called with no data passed to it and  _eof(stdin) indicates
the end of file.  I inserted a debug statement in mod_ext_filter that
shows prior to the filter being called, no data is read from the bucket,
so nothing is piped into stdin for the filter to read.  Yet, after
the external filter exits, the client receives the entity body which is
hundreds or thousands of bytes long.  

   One possible clue, a mod_ext_filter
debug statement reports a content-type of 'unspecified' when calling the
external filter, however the HTTP response has a content-type of text/plain
when the received by the client.  The external filter does not modify
the content or content-type.

  And more strange, if the response
from the origin server is slow (a few seconds), the entity body DOES get
passed to the external filter.

 2)  When receiving a response
with large entity body, such as a 500 KB jpg, the filter gets passed the
first 7746 bytes and nothing else.  The client receives the full response.

  The Apache documentation refers
to a 'standard Unix filter model', but I am unable to find an example of
any Unix filter, let alone a well-behaved one.  My filter reads from
stdin, examines the data, then writes them to stdout.  It seems to
function correctly for the most part, but I sure would like to compare
it to another, well-tested external filter.   

  I've spent many days trying to
get around these problems by disabling chunking, forcing the proxy to use
HTTP 1.0, recoding my I/O processing multiple times, etc., all to no avail.
 Could someone shed some light on these problems?  I need to
get this filter working very soon.

Thanks,
 Mark Zetts