Bug 38889 - mod_jk disregards configuration file order of JkMount
mod_jk disregards configuration file order of JkMount
Status: RESOLVED FIXED
Product: Tomcat Connectors
Classification: Unclassified
Component: Common
unspecified
All Linux
: P2 normal (vote)
: ---
Assigned To: Tomcat Developers Mailing List
:
Depends on:
Blocks:
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Reported: 2006-03-07 21:48 UTC by Steve Revilak
Modified: 2008-10-05 03:09 UTC (History)
0 users



Attachments
Patch to jk_uri_worker_map.c (451 bytes, patch)
2006-03-07 21:50 UTC, Steve Revilak
Details | Diff
jk_uri_worker_map.c patch to order matching based on # of uri path elements (1.68 KB, patch)
2006-03-08 16:49 UTC, Steve Revilak
Details | Diff

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Description Steve Revilak 2006-03-07 21:48:53 UTC
I've been trying out the new version of mod_jk (1.2.15) 

I've been working on upgrading our mod_jk from 1.2.9 to 1.2.15.  (We
use mod_jk primarily on Linux, in conjunction with apache 2.0.53 and
tomcat 5.5.15).

During testing, I noticed several cases of JkMount mappings going to
the wrong set of workers.  By `wrong', I mean `not the same workers as
1.2.9 would have chosen'; this behavior is reproducible with both the
apache 1.3 and 2.0 versions of mod_jk

Here is an example:

  Given JkMount directives:

  JkMount /k/*     worker_k
  JkMount /s/*     worker_s
  JkMount /m/*     worker_m
  JkMount /h/*     worker_h
  JkMount /*.jsp   worker_default

These mount points effectively represent 5 different applications
under a single VirtualHost; and they're handled by 5 different groups
of tomcats.


I'll make a request for the uri "/this-uri-wont-match". Here is the
portion of JkLogFile that attempts matching:


  [Tue Mar 07 16:20:40 2006] [16809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (449): 
Attempting to map URI '/this-uri-wont-match' from 5 maps
  [Tue Mar 07 16:20:40 2006] [16809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/*.jsp'
  [Tue Mar 07 16:20:40 2006] [16809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/k/*'
  [Tue Mar 07 16:20:40 2006] [16809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/s/*'
  [Tue Mar 07 16:20:40 2006] [16809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/m/*'
  [Tue Mar 07 16:20:40 2006] [16809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/h/*'


I see that the code is attempting a `longest-pattern-first' match.
However, the side effect of this is uri's like

  /m/some.jsp
  /h/some-other.jsp
  /s/yet-another.jsp
      ....

become unreachable.  Because mod_jk 1.2.15 uses pattern length, and
not *configuration file* order, there are circumstances where it will
never match the desired servlet container.


Commenting out the call to worker_qsort() (line 297 of
jk_uri_worker_map.c -- diff attached) makes the issue go away.


Would it be possible to go back to matching based on configuration
file order?
Comment 1 Steve Revilak 2006-03-07 21:50:31 UTC
Created attachment 17844 [details]
Patch to jk_uri_worker_map.c
Comment 2 Steve Revilak 2006-03-08 16:47:42 UTC
I see what mod_jk is doing in attempting to match the longest uri
pattern first.  The Servlet specification 2.4 (section SRV.11.1) says

   The container will recursively try tomatch the longest
   path-prefix. This is done by stepping down the path tree a
   directory at a time, using the / character as a path
   separator. The longest match determines the servlet selected.

This definitely favors a longest match.  However, I think it also
implies that 'longest' means 'most uri path elements'.  I'd like to
submit a patch that brings mod_jk closer to this behavior.

I'll attach the patch to this issue.  Below are some JkLogFile
examples to demonstrate what the patch does.

				* * *


For what follows, I've set up an apache configuration with this list
of workers defined:


  JkMount /*.jsp                  worker_default
  JkMount /a/*                    worker_a
  JkMount /a/1/*                  worker_a1
  JkMount /a/1/2/*                worker_a12
  JkMount /golly-gee-batman/*     worker_golly


This is the order in which the JkMount directives appear in the httpd
configuration -- the goal is to verify that `most path elements' gets
preference.  The first two samples of log output show a stock mod_jk
1.2.15; subsequent examples show a patched mod_jk 1.2.15.


				* * *

# (unpatched mod_jk-1.2.15)
#
# Here, we submit a non-matching URI, just to see the iteration
# order that mod_jk will use when attempting to locate a worker for
# the request.

[Wed Mar 08 10:49:22 2006] [18652:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (449): 
Attempting to map URI '/not-found' from 5 maps
[Wed Mar 08 10:49:22 2006] [18652:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/golly-gee-batman/*'
[Wed Mar 08 10:49:22 2006] [18652:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 10:49:22 2006] [18652:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/*.jsp'
[Wed Mar 08 10:49:22 2006] [18652:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/a/1/*'
[Wed Mar 08 10:49:22 2006] [18652:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/a/*'


# (unpatched mod_jk-1.2.15)
#
# Here, we have a request for /a/1/foo.jsp.  Log entries below show
# thie request being mapped to '/*.jsp', not '/a/1/*'
#
[Wed Mar 08 10:52:56 2006] [18653:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (449): 
Attempting to map URI '/a/1/foo.jsp' from 5 maps
[Wed Mar 08 10:52:56 2006] [18653:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/golly-gee-batman/*'
[Wed Mar 08 10:52:56 2006] [18653:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 10:52:56 2006] [18653:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (461): 
Attempting to map context URI '/*.jsp'
[Wed Mar 08 10:52:56 2006] [18653:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (475): 
Found a wildchar match worker_default -> /*.jsp


				* * *


# (patched mod_jk-1.2.15)
#
# Here is the same "/not-found" request, made against mod_jk-1.2.15,
# with the submitted patch.  Note that the matching order reflects
# the number of uri path elements in the JkMount directive.
#
[Wed Mar 08 11:31:15 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (487): 
Attempting to map URI '/not-found' from 5 maps
[Wed Mar 08 11:31:15 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 11:31:15 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/*'
[Wed Mar 08 11:31:15 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/golly-gee-batman/*'
[Wed Mar 08 11:31:15 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/*'
[Wed Mar 08 11:31:15 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/*.jsp'


# (patched mod_jk-1.2.15)
#
#  Request for '/a/1/2/foo.jsp'
#
[Wed Mar 08 11:32:29 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (487): 
Attempting to map URI '/a/1/2/foo.jsp' from 5 maps
[Wed Mar 08 11:32:29 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 11:32:29 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (513): 
Found a wildchar match worker_a12 -> /a/1/2/*


# (patched mod_jk-1.2.15)
#
# Request for '/a/1/foo.jsp'
#
#
[Wed Mar 08 11:33:20 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (487): 
Attempting to map URI '/a/1/foo.jsp' from 5 maps
[Wed Mar 08 11:33:20 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 11:33:20 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/*'
[Wed Mar 08 11:33:20 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (513): 
Found a wildchar match worker_a1 -> /a/1/*



# (patched mod_jk-1.2.15)
#
# Request for '/a/foo.jsp'
#
#
[Wed Mar 08 11:34:01 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (487): 
Attempting to map URI '/a/foo.jsp' from 5 maps
[Wed Mar 08 11:34:01 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 11:34:01 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/*'
[Wed Mar 08 11:34:01 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/golly-gee-batman/*'
[Wed Mar 08 11:34:01 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/*'
[Wed Mar 08 11:34:01 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (513): 
Found a wildchar match worker_a -> /a/*


# (patched mod_jk-1.2.15)
#
# Request for '/golly-gee-batman/foo.jsp'
#
#
[Wed Mar 08 11:34:53 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (487): 
Attempting to map URI '/golly-gee-batman/foo.jsp' from 5 maps
[Wed Mar 08 11:34:53 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 11:34:53 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/*'
[Wed Mar 08 11:34:53 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/golly-gee-batman/*'
[Wed Mar 08 11:34:53 2006] [20808:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (513): 
Found a wildchar match worker_golly -> /golly-gee-batman/*


# (patched mod_jk-1.2.15)
#
# Request for '/foo.jsp'
#
[Wed Mar 08 11:35:27 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (487): 
Attempting to map URI '/foo.jsp' from 5 maps
[Wed Mar 08 11:35:27 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/2/*'
[Wed Mar 08 11:35:27 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/1/*'
[Wed Mar 08 11:35:27 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/golly-gee-batman/*'
[Wed Mar 08 11:35:27 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/a/*'
[Wed Mar 08 11:35:27 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (499): 
Attempting to map context URI '/*.jsp'
[Wed Mar 08 11:35:27 2006] [20809:0000] [debug] map_uri_to_worker::jk_uri_worker_map.c (513): 
Found a wildchar match worker_default -> /*.jsp


Comment 3 Steve Revilak 2006-03-08 16:49:47 UTC
Created attachment 17848 [details]
jk_uri_worker_map.c patch to order matching based on # of uri path elements
Comment 4 Mladen Turk 2006-03-16 08:10:39 UTC
Commited.
Thanks!