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From Jim Riggs <apache-li...@riggs.me>
Subject Re: mod_proxy_ajp: ignoring flush before headers (again)
Date Wed, 03 Aug 2011 14:48:15 GMT
This does appear to work.  Our automated tests are running right now.  Shall I submit a but
with this patch attached?


On Aug 3, 2011, at 7:43 AM, Plüm, Rüdiger, VF-Group wrote:

> Can you please try if the following patch fixes your issue?
> 
> Index: mod_proxy_ajp.c
> ===================================================================
> --- mod_proxy_ajp.c     (revision 1150558)
> +++ mod_proxy_ajp.c     (working copy)
> @@ -506,16 +506,18 @@
>                             if (bb_len != -1)
>                                 conn->worker->s->read += bb_len;
>                         }
> -                        if (ap_pass_brigade(r->output_filters,
> -                                            output_brigade) != APR_SUCCESS) {
> -                            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
> -                                          "proxy: error processing body.%s",
> -                                          r->connection->aborted ?
> -                                          " Client aborted connection." : "");
> -                            output_failed = 1;
> +                        if (headers_sent) {
> +                            if (ap_pass_brigade(r->output_filters,
> +                                                output_brigade) != APR_SUCCESS) {
> +                                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
> +                                              "proxy: error processing body.%s",
> +                                              r->connection->aborted ?
> +                                              " Client aborted connection." : "");
> +                                output_failed = 1;
> +                            }
> +                            data_sent = 1;
> +                            apr_brigade_cleanup(output_brigade);
>                         }
> -                        data_sent = 1;
> -                        apr_brigade_cleanup(output_brigade);
>                     }
>                 }
>                 else {
> 
> Currently the code sends an empty brigade in your case which also triggers the sending
of headers by httpd.
> 
> Regards
> 
> Rüdiger
> 
>> -----Original Message-----
>> From: Jim Riggs 
>> Sent: Dienstag, 2. August 2011 18:03
>> To: dev@httpd.apache.org
>> Subject: mod_proxy_ajp: ignoring flush before headers (again)
>> 
>> For some (old 2007) context, see:
>> 
>> http://markmail.org/message/btwcnbl2i7ftwj4n
>> 
>> https://community.jivesoftware.com/message/201787
>> 
>> 
>> I am proxying an app via AJP to Tomcat 6/7.  In certain 
>> circumstances, it appears that the app (or possibly Tomcat) 
>> is erroneously sending a flush before the headers have been 
>> sent.  In r579999, Jim added an exception to handle this 
>> situation with the intention of ignoring the flush.  I'm not 
>> sure it's working quite right, though, as the brigade is 
>> still getting passed through the filter chain.  So, 
>> ap_headers_output_filter() is getting called too soon, I 
>> think.  (I am no expert in the httpd code, so I'm not sure 
>> this is really the problem.)
>> 
>> Can any of you who ARE experts in the code tell me what you 
>> think of the issue and how we can fix it?  I'm thinking that 
>> if we are ignoring a flush at mod_proxy_ajp.c:448 (in 2.2.x), 
>> we should not be calling ap_pass_brigade() at line 472, but I 
>> don't know if there are any ramifications of that.
>> 
>> The symptom is that when this issue happens, the user gets 
>> prompted to save a file (Content-Type returned by httpd is 
>> 'text/plain' even though Tomcat is returning 
>> 'text/html;charset=utf-8').  Below is some debug output 
>> showing correct and incorrect behavior:
>> 
>> Correct:
>> 
>> [Tue Aug 02 09:34:50 2011] [debug] mod_proxy_ajp.c(266): 
>> proxy: APR_BUCKET_IS_EOS
>> [Tue Aug 02 09:34:50 2011] [debug] mod_proxy_ajp.c(271): 
>> proxy: data to read (max 8186 at 4)
>> [Tue Aug 02 09:34:50 2011] [debug] mod_proxy_ajp.c(286): 
>> proxy: got 0 bytes of data
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(687): 
>> ajp_read_header: ajp_ilink_received 04
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(697): 
>> ajp_parse_type: got 04
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(516): 
>> ajp_unmarshal_response: status = 200
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(537): 
>> ajp_unmarshal_response: Number of headers is = 5
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[0] [Pragma] = [No-cache]
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[1] [Cache-Control] = [no-cache]
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[2] [Expires] = [Wed, 31 Dec 
>> 1969 18:00:00 CST]
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[4] [Content-Type] = 
>> [text/html;charset=utf-8]
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(609): 
>> ajp_unmarshal_response: ap_set_content_type done
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(687): 
>> ajp_read_header: ajp_ilink_received 03
>> [Tue Aug 02 09:34:50 2011] [debug] ajp_header.c(697): 
>> ajp_parse_type: got 03
>> [Tue Aug 02 09:34:50 2011] [debug] mod_headers.c(756): 
>> headers: ap_headers_output_filter()
>> 
>> 
>> Incorrect (notice how ap_headers_output_filter() is called 
>> before the headers are received):
>> 
>> [Tue Aug 02 09:32:18 2011] [debug] mod_proxy_ajp.c(266): 
>> proxy: APR_BUCKET_IS_EOS
>> [Tue Aug 02 09:32:18 2011] [debug] mod_proxy_ajp.c(271): 
>> proxy: data to read (max 8186 at 4)
>> [Tue Aug 02 09:32:18 2011] [debug] mod_proxy_ajp.c(286): 
>> proxy: got 0 bytes of data
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(687): 
>> ajp_read_header: ajp_ilink_received 03
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(697): 
>> ajp_parse_type: got 03
>> [Tue Aug 02 09:32:18 2011] [debug] mod_proxy_ajp.c(452): 
>> Ignoring flush message received before headers
>> [Tue Aug 02 09:32:18 2011] [debug] mod_headers.c(756): 
>> headers: ap_headers_output_filter()
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(687): 
>> ajp_read_header: ajp_ilink_received 03
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(697): 
>> ajp_parse_type: got 03
>> [Tue Aug 02 09:32:18 2011] [debug] mod_proxy_ajp.c(452): 
>> Ignoring flush message received before headers
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(687): 
>> ajp_read_header: ajp_ilink_received 04
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(697): 
>> ajp_parse_type: got 04
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(516): 
>> ajp_unmarshal_response: status = 200
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(537): 
>> ajp_unmarshal_response: Number of headers is = 5
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[0] [Pragma] = [No-cache]
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[1] [Cache-Control] = [no-cache]
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[2] [Expires] = [Wed, 31 Dec 
>> 1969 18:00:00 CST]
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[3] [Set-Cookie] = 
>> [JSESSIONID=39968855F543CA08A440E6136EA6FC28.app1; 
>> Path=/tomcat-manager; Secure; HttpOnly]
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(599): 
>> ajp_unmarshal_response: Header[4] [Content-Type] = 
>> [text/html;charset=utf-8]
>> [Tue Aug 02 09:32:18 2011] [debug] ajp_header.c(609): 
>> ajp_unmarshal_response: ap_set_content_type done
>> 
>> 


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