Re: libresolv/poll() problems

[John Kennedy <jk@csuchico.edu>]

01/30/99 @ 04:09:39 PM (Saturday)

> 01/30/99 @ 10:43:31 AM (Saturday)
> 
>   I just finished trying to figure out what was causing my sendmail
> (with anti-spam) to be totally choking on the GNOME mailing list.
> In trying to look up redhat.com (temporarily down while they're moving,
> I guess), I get hung up in libresolv on a poll().  I can link against
> BIND's resolver and avoid it and I have to chase another DHCPd problem
> before I get back to this, but someone more involved might want to take a
> look at it.  As I recall, glibc-2.1.x is trying to change over to using
> poll() wherever it can so that was probably a recent change.

  $&$#&$#!!  I hate a problem that I can't find a good, clean little
test for.

  All things being equal, recompiling sendmail with BIND fixed the
problem, but in doing so I exhausted all my DNS-problem-email.  I haven't
been able to forge it or reproduce it.  ):  I'm recompiling glibc-2.0.112
with `-g' and sendmail as well (back to using libresolv), but I haven't
gotten any more lingering daemons.

  I grabbed this before I started recompiling everything with `-g',
but it doesn't show the arguments of course:

    [gdb sendmail 2569]
	GNU gdb 4.17.0.5 with Linux/x86 hardware watchpoint and FPU support
	...
	/usr/sbin/2569: No such file or directory.
	Attaching to program `/usr/sbin/sendmail', process 2569
	Reading symbols from /lib/libresolv.so.2...done.
	Reading symbols from /lib/libc.so.6...done.
	Reading symbols from /lib/ld-linux.so.2...done.
	Reading symbols from /lib/libnss_compat.so.2...done.
	Reading symbols from /lib/libnsl.so.1...done.
	Reading symbols from /lib/libnss_files.so.2...done.
	Reading symbols from /lib/libnss_dns.so.2...done.
	Reading symbols from /lib/libnss_nis.so.2...done.
	0x400cdd60 in __poll ()

	(gdb) where
	#0  0x400cdd60 in __poll ()
	#1  0x400216a3 in __res_send ()
	#2  0x40020730 in res_query ()
	#3  0x40020b41 in res_querydomain ()
	#4  0x805905e in dns_getcanonname ()
	#5  0x8062de3 in getcanonname ()
	#6  0x8052a48 in host_map_lookup ()
	#7  0x806a52e in map_lookup ()
	#8  0x806a080 in rewrite ()
	#9  0x806a3a6 in callsubr ()
	#10 0x806a1e1 in rewrite ()
	#11 0x8068d23 in parseaddr ()
	#12 0x805a488 in setsender ()
	#13 0x80789ec in smtp ()
	#14 0x8060bd7 in main ()
	#15 0x4003e8af in __libc_start_main ()

  They may not have been perpetually hung.  I was getting shotgunned at
the time and didn't have the luxury of keeping the problem around
to analyze.

  Sorry I can't be more useful on this one, unless it happens again.

								--- john