DNSBL helper not answering

Daniel Gehriger daniel.gehriger@linkcad.com
Fri Nov 24 17:09:20 UTC 2006


Vernon Schryver wrote:
>> #undef HAVE__RES
>> #undef HAVE_RES_INIT
>> #undef HAVE_RES_QUERY
>> #undef HAVE_DN_EXPAND
> 
> Those lines shows that ./configure decided _res and the other BIND
> resolver hooks are absent.  Is the BIND resolver available with -lresolv?
> Do those lines change if you convince ./configure to use -lresolv with
>     LIB=-lresolv ./configure ...
> or 
>     setenv LIB -lresolv; ./configure ...

No, this doesn't change anything (and I did rm config.cache). But 
manually editing configure and adding -lresolv (target system "Linux") 
to LIBS yields:

> /* BIND resolver library */
> #define HAVE_RESOLV_H 1
> #define HAVE_ARPA_NAMESER_H 1
> #undef HAVE__RES
> #undef HAVE_RES_INIT
> #define HAVE_RES_QUERY 1
> #define HAVE_DN_EXPAND 1

To get it to compile, I also had to link against the pthread library.

Maybe you're interested in the symbols contained in libresolv.so:

> vps183:~ # nm /lib/libresolv.so.2  | grep -i -E '(res_.?init|res_query|dn_expand)'
> 000044d0 T __dn_expand
>          U __res_init@@GLIBC_2.2
>          U __res_ninit@@GLIBC_2.2
> 000065c0 T __res_query
> 000067e0 T __res_querydomain
> 000044d0 W dn_expand
> 000065c0 W res_query
> 000067e0 W res_querydomain

I'm now testing if this makes any difference.

> If so, I'll try to figure out how to make ./configure add -lresolv for
> Linux systems that have that library.

case "$TARGET_SYS" in
     Linux)
         PTHREAD_LDFLAGS="$PTHREAD_LDFLAGS -pthread"
         LIBS="$LIBS -lresolv"
         ;;

> Separately, does grossly setting inflating the timeouts seem to make the
> problem go away?
>   -Bset:msg-secs=100  -Bset:URL-secs=91
> (I vaguely recall something about very old default resolver timeouts
> of 90 seconds.)

No, I already tried that. It's not a timeout problem - the DNSBL helper 
just won't start, not even after 90 seconds. Besides, I also had to 
update the corresponding timeouts in postfix - and the sending MX may 
also have its own timeout below 90 seconds.

- Daniel



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