ipptool hangs in http_read despite timeout (-T 10)

[michaelrsweet]

Version: 2.0.0
CUPS.org User: tometzky

I'm using ipptool (really ipptool-static) on Linux (CentOS6 x86_64, manually compiled ipptool) to check printer queue (Canon iR3225) like this:

DEVICE_URI="ipp://printerhostname/ipp"
IPPTOOL="ipptool"
IPPTOOL_GET_QUEUED_JOB_COUNT='
{
NAME "Get queued job count using Get-Printer-Attributes"
OPERATION Get-Printer-Attributes

GROUP operation-attributes-tag
ATTR charset attributes-charset utf-8
ATTR language attributes-natural-language en
ATTR uri printer-uri $uri

STATUS successful-ok

DISPLAY queued-job-count

}
'
$IPPTOOL -c -T 10 "$DEVICE_URI" /dev/stdin <<< "$IPPTOOL_GET_QUEUED_JOB_COUNT"
queued-job-count
0

But despite using "-T 10" ipptool process hanged for 18 hours in http_read function. Even restarting a printer did not help as ipptool does not use TCP SO_KEEPALIVE.

Please enable SO_KEEPALIVE for ipptool connections by default or at least add an option to enable it.

Here's a backtrace from hanging process:
#0 0x00007f0236302b12 in __libc_recv (fd=, buf=0x7f02387601e1, n=8, flags=)

at ../sysdeps/unix/sysv/linux/x86_64/recv.c:30

#1 0x00007f023674ea6f in recv (http=0x7f023875bab0, buffer=0x7f02387601e1 "\003", length=8)

at /usr/include/bits/socket2.h:45

#2 http_read (http=0x7f023875bab0, buffer=0x7f02387601e1 "\003", length=8) at http.c:4079
#3 0x00007f023674f571 in httpRead2 (http=0x7f023875bab0, buffer=0x7f02387601e1 "\003", length=)

at http.c:2129

#4 0x00007f023675891f in ipp_read_http (http=0x7f023875bab0, buffer=, length=8) at ipp.c:6834
#5 0x00007f02367592bd in ippReadIO (src=0x7f023875bab0, cb=0x7f02367588b0 <ipp_read_http>, blocking=1,

parent=<value optimized out>, ipp=0x7f023875ef60) at ipp.c:2999

#6 0x00007f023675f73b in cupsGetResponse (http=0x7f023875bab0, resource=) at request.c:402
#7 0x00007f0236744753 in do_tests (outfile=, vars=0x7fff05dbf320,

testfile=0x7fff05dc2d1d "/dev/stdin") at ipptool.c:2577

#8 0x00007f02367494f4 in main (argc=6, argv=0x7fff05dc0ab8) at ipptool.c:670

I'm attaching a compressed core file (from CentOS 6.6 x86_64 with all updates until today) - it may help with debugging this.

[michaelrsweet]

CUPS.org User: tometzky

I couldn't attach a core file directly to this report. Please download from http://prhn.ato.waw.pl/~tometzky/tmp/core.10765.xz

[michaelrsweet]

CUPS.org User: tometzky

This process did not even react to TERM signal. I had to use 'kill -9' to kill it.

[michaelrsweet]

CUPS.org User: mike

ipptool catches SIGTERM when timeouts are in use - a second SIGTERM will kill it.

It should not be possible for libcups to hang like this - when timeouts are set the read should only occur if input is available.

Investigating.

[michaelrsweet]

CUPS.org User: mike

Fixed in Subversion repository.

[michaelrsweet]

"str4515.patch":

Index: cups/ipp.c

--- cups/ipp.c (revision 12463)
+++ cups/ipp.c (working copy)
@@ -6830,7 +6830,23 @@
break;
}
}

• else if (http->used == 0 && http->timeout_value > 0)
• {

• /*
  

•  \* Wait up to timeout seconds for more data on blocking sockets...
  

•  */
  

•  if (!httpWait(http, (int)(1000 * http->timeout_value)))
  

•  {
  

•   /*
  

• * Signal no data...
• */

• bytes = -1;
• break;

•  }
  

• }

if ((bytes = httpRead2(http, (char *)buffer, length - (size_t)tbytes)) < 0)
{
#ifdef WIN32