DO NOT REPLY [Bug 30398] New: - Wrong content type when using mod_jk with mod_cache

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http://issues.apache.org/bugzilla/show_bug.cgi?id=30398

Wrong content type when using mod_jk with mod_cache

           Summary: Wrong content type when using mod_jk with mod_cache
           Product: Tomcat 5
           Version: 5.0.18
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: Native:JK
        AssignedTo: tomcat-dev@jakarta.apache.org
        ReportedBy: ruediger.pluem@vodafone.com


Hi,

I discovered a problem with the cooperation between mod_jk and Apache 2.0's
mod_cache.
I discovered the problem while I tried to cache Tomcat responses delivered by
mod_jk with mod_cache. At the first look everything works fine and the content
is served and cached, but after the content is cached the content type of the
cache delivered content is always set to text/plain regardless of the content
type of the original Tomcat delivered content.

My environment:

Apache: 2.0.50
mod_jk: 1.2.5

OS: Linux
Tomcat: 5.0.18

Excerpt from my Apache configuration:

<VirtualHost 192.168.2.4:80>
ServerName www.something.de
ServerAdmin admin@www.something.de
DocumentRoot "/var/httpd/test/www.something.de/docs"
ErrorLog "|/opt/apache-2.0.50/bin/rotatelogs /var/httpd/test/www.something.de/lo
gs/error_log 86400"
CustomLog "|/opt/apache-2.0.50/bin/rotatelogs /var/httpd/test/www.something.de/l
ogs/access_log 86400" combined


<Directory /var/httpd/test/www.something.de/docs>
   Options None
   AllowOverride None
</Directory>

JkMount /* worker_ajp13

CacheRoot /var/httpd/test/cache
CacheSize 256
CacheEnable disk /test
CacheDirLevels 5
CacheDirLength 3

CacheMaxExpire 60
CacheIgnoreNoLastMod On
CacheIgnoreCacheControl On
CacheDefaultExpire 60

</VirtualHost>

I believe that I found the reason for this, but I am not quite sure if it
is a bug of mod_disk_cache or mod_jk. Maybe a separate discussion for the
core developers :-).

mod_disk_cache stores the content type of a cached response together with the
other headers of this response in a separate file (write_headers).
For storing the Content-Type it reads the information only from the headers_out
table and not from the content_type field in the request_rec structure.

On the other hand mod_jk's ws_start_response only sets the content type via
ap_set_content_type (thus only setting the content_type field) and does not
add the header Content-Type to the headers_out table.

To cut a long story short, the following patch to mod_jk.c (Apache 2.0 version)
fixes this problem:

--- jakarta-tomcat-connectors-jk-1.2.5-src/jk/native/apache-2.0/mod_jk.c.orig
2003-09-06 17:37:20.000000000 +0200
+++ jakarta-tomcat-connectors-jk-1.2.5-src/jk/native/apache-2.0/mod_jk.c
2004-07-29 12:34:40.000000000 +0200
@@ -254,6 +254,8 @@
             /* and it make jk useable with deflate using */
             /* AddOutputFilterByType DEFLATE text/html */
             ap_set_content_type(r, tmp);
+            apr_table_set(r->headers_out,
+                          header_names[h], tmp);
         } else if(!strcasecmp(header_names[h], "Location")) {
 #ifdef AS400
             /* Fix escapes in Location Header URL*/

The diff is against 1.2.5 but it is also applicable against 1.2.6.

Another approach to solve this problem would be to adjust write_headers
in mod_disk_cache.c of Apache 2.0 accordingly, but as said above the discussion
of the correct approach is another story, where I cannot distribute anything.

Regards

Rüdiger Plüm

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