Bug 496451 - Custom bash cgi scripts fail with cups 1.3.7-8
Custom bash cgi scripts fail with cups 1.3.7-8
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: cups (Show other bugs)
x86_64 Linux
low Severity high
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Assigned To: Tim Waugh
Depends On:
  Show dependency treegraph
Reported: 2009-04-19 06:59 EDT by Opher Shachar
Modified: 2013-03-19 12:13 EDT (History)
2 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2013-03-19 12:13:34 EDT
Type: ---
Regression: ---
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Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
A custom bash cgi script (1.52 KB, text/plain)
2009-04-19 06:59 EDT, Opher Shachar
no flags Details

  None (edit)
Description Opher Shachar 2009-04-19 06:59:26 EDT
Created attachment 340224 [details]
A custom bash cgi script

Description of problem:
For two years now we're running printer servers on RHEL 5,5.1,5.2 x86_64 (and before that on Fedora) - atop cups 1.2.4.
We have a custom _bash_ cgi script (attached) that basically outputs something like:

    Location: /printers/
    Set-Cookie: RASHUT=SUPPORT; path=/
(ex. in response to /rashut.cgi?RASHUT=SUPPORT)
to set a cookie and redirect the client to the printers page.
This works fine on the above mentioned platforms.

We set up a test system running RHEL 5.3 - with cups 1.3.7 - and now this script fails in the following way:

    Every 2 out of 5 (40% of) request fails:
    1. The client (IE 7/Win XP) stalls for 300 seconds
    2. The log file - error_log - shows this:

D [18/Apr/2009:01:50:05 +0300] cupsdAcceptClient: skipping getpeercon()
D [18/Apr/2009:01:50:05 +0300] cupsdAcceptClient: 13 from (IPv4)
D [18/Apr/2009:01:50:05 +0300] cupsdReadClient: 13 GET /rashut.cgi?RASHUT=YVN HTTP/1.1
D [18/Apr/2009:01:50:05 +0300] cupsdAuthorize: No authentication data provided.
D [18/Apr/2009:01:50:05 +0300] cupsdIsAuthorized: username=""
D [18/Apr/2009:01:50:05 +0300] cupsdSendError: 13 code=401 (Unauthorized)
D [18/Apr/2009:01:50:05 +0300] cupsdSendHeader: WWW-Authenticate: Basic realm="CUPS"
D [18/Apr/2009:01:50:05 +0300] cupsdCloseClient: 13
D [18/Apr/2009:01:50:05 +0300] cupsdAcceptClient: skipping getpeercon()
D [18/Apr/2009:01:50:05 +0300] cupsdAcceptClient: 13 from (IPv4)
D [18/Apr/2009:01:50:05 +0300] cupsdReadClient: 13 GET /rashut.cgi?RASHUT=YVN HTTP/1.1
D [18/Apr/2009:01:50:05 +0300] cupsdAuthorize: Authorized as 022419873 using Basic
D [18/Apr/2009:01:50:05 +0300] cupsdIsAuthorized: username="022419873"
D [18/Apr/2009:01:50:05 +0300] [CGI] /usr/share/doc/cups-1.3.7/he/rashut.cgi started - PID = 31846
I [18/Apr/2009:01:50:05 +0300] Started "/usr/share/doc/cups-1.3.7/he/rashut.cgi" (pid=31846)
D [18/Apr/2009:01:50:05 +0300] cupsdSendCommand: 13 file=16
D [18/Apr/2009:01:50:06 +0300] PID 31846 (/usr/share/doc/cups-1.3.7/he/rashut.cgi) exited with no errors.
D [18/Apr/2009:01:55:07 +0300] Closing client 13 after 300 seconds of inactivity...
D [18/Apr/2009:01:55:07 +0300] cupsdCloseClient: 13

    3. At that point the client (IE 7/Win XP) continues and shows this in its logs:
        HTTP/1.0 200 This buggy server did not return headers
        HTTP/1.1 303 See Other
        Date: Sat, 18 Apr 2009 00:46:08 GMT
        Server: CUPS/1.2
        Connection: Keep-Alive
        Keep-Alive: timeout=60
        Content-Language: he_IL
        Content-Length: 0
        Location: /printers/?QUERY=NAT
    4. Notice that the `Set-Cookie' header was not received nor the `blank' line after the last header.

I have found (after 3 hours of scratching and standing on my head) two workarounds. Detailed later under `Additional info'.

Version-Release number of selected component (if applicable):
RHEL 5.3, cups 1.3.7-8, bash 3.2-24, ksh 20080202-2, coreutils 5.97-19

How reproducible:

Steps to Reproduce:
1. Place rashut.cgi in /usr/share/cups/doc
2. Require authentication for the CUPS server. eg. in cupsd.conf
    Listen *:631
    <Location />
      AuthType Basic
      Require valid-user
      Satisfy any
      Order allow,deny
      Allow localhost
3. Configure cups to handle cgi scripts. In /etc/cups/cgi.types add:
      application/x-httpd-cgi cgi
4. Restart cups
5. From a client machine browse to: 
Actual results:
In 2 out of 5 requests the browser stalls for 300 seconds.

Expected results:
Always be promptly redirected to /printers and get the cookie RASHUT.

Additional info:
As mentioned I have found (after 3 hours of scratching and standing on my head) two workarounds:
  1. make the rashut.cgi script a ksh script. eg. change 
  2. add `|cat' to the `echo' command in rashut.cgi. eg.:

     echo -e "Location: /printers/${RASHUT:+?QUERY=$RASHUT}
     Set-Cookie: RASHUT=${COOKIE:-$RASHUT}; path=/

then all request are answered correctly.
Comment 1 Tim Waugh 2009-05-14 09:07:35 EDT
I wonder if this might be related to a bug I've investigated recently.  I reported it upstream here:

Does it look like it might be the cause?
Comment 2 Opher Shachar 2009-05-17 03:08:17 EDT
I'm not sure. At least the output of strace gives different results for bash and ksh:

echo -e "Location: /printers/${RASHUT:+?QUERY=$RASHUT}
Set-Cookie: RASHUT=${COOKIE:-$RASHUT}; path=/
" >~/a.a'|strace -ewrite -s80 bash
write(1, "Location: /printers/?QUERY=SUPPORT\n", 35) = 35
write(1, "Set-Cookie: RASHUT=SUPPORT; path=/\n", 35) = 35
write(1, "\n", 1)                       = 1

echo -e "Location: /printers/${RASHUT:+?QUERY=$RASHUT}
Set-Cookie: RASHUT=${COOKIE:-$RASHUT}; path=/
" >~/a.a'|strace -ewrite -s80 ksh
write(1, "Location: /printers/?QUERY=SUPPORT\nSet-Cookie: RASHUT=SUPPORT; path=/\n\n", 71) = 71
Comment 3 Tim Waugh 2009-07-03 07:14:12 EDT
Are you able to try the patch (str3194.patch) from that CUPS bug report to see if it makes a difference?

I see you've also reported STR #3221 -- is that related to this bug at all?
Comment 4 Opher Shachar 2009-07-05 03:56:11 EDT
I'll give the patch for STR #3194 a try; It'll take me to the and of this week, though.

As for STR #3221, it is unrelated.
Comment 5 Phil Knirsch 2009-10-12 07:56:56 EDT
Any news on testing STR #3194?

Thanks & regards, Phil
Comment 6 Opher Shachar 2009-10-12 08:23:40 EDT
wow ... terribly sorry. It's been more than a week :)
I never got to checking this (the workarounds were acceptable).
I'll try the patch and post on any news, not this week though.

Thanks for the reminder.
Comment 7 Tim Waugh 2012-03-26 08:02:37 EDT
Any news?
Comment 8 Jiri Popelka 2013-03-19 12:13:34 EDT
RHEL-5.10 (the next RHEL-5 minor release) is going to be the first production phase 2 [1] release of RHEL-5.
Since phase 2 we'll be addressing only security and critical issues.

I'm closing this ticket because it's neither security nor critical.

[1] https://access.redhat.com/support/policy/updates/errata/

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