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This queue is for tickets about the Net-DNS CPAN distribution.

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The Basics
Id: 96812
Status: resolved
Priority: 0/
Queue: Net-DNS
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Owner: Nobody in particular
Requestors: tore [...] fud.no
Cc:
AdminCc:
Bug Information
Severity: (no value)
Broken in: (no value)
Fixed in: (no value)

History Show all quoted text
  Sun Jun 29 06:29:22 2014 tore [...] fud.no - Ticket created
Subject: Net::DNS::Resolver->new() hangs for 5 minutes if nameserver "::" exists
Date: Sun, 29 Jun 2014 12:29:02 +0200
To: bug-Net-DNS [...] rt.cpan.org
From: Tore Anderson <tore [...] fud.no>
For some reason I ended up with a /etc/resolv.conf containing the following entries: nameserver 2001:4600:4:fff::54 nameserver :: This breaks Net::DNS - the ->new() method hangs for 5 minutes before returning. Once I get rid of "nameserver ::", it works fine again and the method takes just a few milliseconds. While one could certainly argue that having "nameserver ::" is broken in itself, the system name servers are usually automatically configured based on information provided by equipment of very varying quality. Hence, this is a situation a clueless user might easily and inadvertently encounter. For this reason I think it would be better if Net::DNS was robust enough to avoid being negatively impacted by this situation. Below follows the information requested on the http://www.net-dns.org/. Best regards, Tore Anderson $ perl -V Summary of my perl5 (revision 5 version 18 subversion 2) configuration: Platform: osname=linux, osvers=3.11.9-200.fc19.x86_64, archname=x86_64-linux-thread-multi uname='linux buildvm-12.phx2.fedoraproject.org 3.11.9-200.fc19.x86_64 #1 smp wed nov 20 21:22:24 utc 2013 x86_64 x86_64 x86_64 gnulinux ' config_args='-des -Doptimize=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -Dccdlflags=-Wl,--enable-new-dtags -Dlddlflags=-shared -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -Wl,-z,relro -Dshrpdir=/usr/lib64 -DDEBUGGING=-g -Dversion=5.18.2 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dprefix=/usr -Dvendorprefix=/usr -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl5 -Dsitearch=/usr/local/lib64/perl5 -Dprivlib=/usr/share/perl5 -Dvendorlib=/usr/share/perl5/vendor_perl -Darchlib=/usr/lib64/perl5 -Dvendorarch=/usr/lib64/perl5/vendor_perl -Darchname=x86_64-linux-thread-multi -Dlibpth=/usr/local/lib64 /lib64 /usr/lib64 -Duseshrplib -Dusethreads -Duseithreads -Dusedtrace=/usr/bin/dtrace -Duselargefiles -Dd_semctl_semun -Di_db -Ui _ndbm -Di _gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl=n -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr -Dd_gethostent_r_proto -Ud_endhostent_r_proto -Ud_sethostent_r_proto -Ud_endprotoent_r_proto -Ud_setprotoent_r_proto -Ud_endservent_r_proto -Ud_setservent_r_proto -Dscriptdir=/usr/bin -Dusesitecustomize' hint=recommended, useposix=true, d_sigaction=define useithreads=define, usemultiplicity=define useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef use64bitint=define, use64bitall=define, uselongdouble=undef usemymalloc=n, bincompat5005=undef Compiler: cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64', optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic', cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include' ccversion='', gccversion='4.8.2 20131212 (Red Hat 4.8.2-7)', gccosandvers='' intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678 d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16 ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8 alignbytes=8, prototype=define Linker and Libraries: ld='gcc', ldflags =' -fstack-protector' libpth=/usr/local/lib64 /lib64 /usr/lib64 libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc -lgdbm_compat perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc libc=, so=so, useshrplib=true, libperl=libperl.so gnulibc_version='2.18' Dynamic Linking: dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,--enable-new-dtags' cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -Wl,-z,relro ' Characteristics of this binary (from libperl): Compile-time options: HAS_TIMES MULTIPLICITY PERLIO_LAYERS PERL_DONT_CREATE_GVSV PERL_HASH_FUNC_ONE_AT_A_TIME_HARD PERL_IMPLICIT_CONTEXT PERL_MALLOC_WRAP PERL_PRESERVE_IVUV PERL_SAWAMPERSAND USE_64_BIT_ALL USE_64_BIT_INT USE_ITHREADS USE_LARGE_FILES USE_LOCALE USE_LOCALE_COLLATE USE_LOCALE_CTYPE USE_LOCALE_NUMERIC USE_PERLIO USE_PERL_ATOF USE_REENTRANT_API USE_SITECUSTOMIZE Locally applied patches: Fedora Patch1: Removes date check, Fedora/RHEL specific Fedora Patch3: support for libdir64 Fedora Patch4: use libresolv instead of libbind Fedora Patch5: USE_MM_LD_RUN_PATH Fedora Patch6: Skip hostname tests, due to builders not being network capable Fedora Patch7: Dont run one io test due to random builder failures Fedora Patch9: Fix find2perl to translate ? glob properly (RT#113054) Fedora Patch10: Update h2ph(1) documentation (RT#117647) Fedora Patch11: Update pod2html(1) documentation (RT#117623) Fedora Patch12: Disable ornaments on perl5db AutoTrace tests (RT#118817) Fedora Patch14: Do not use system Term::ReadLine::Gnu in tests (RT#118821) Fedora Patch15: Define SONAME for libperl.so Fedora Patch16: Install libperl.so to -Dshrpdir value Fedora Patch18: Fix crash with \&$glob_copy (RT#119051) Fedora Patch19: Fix coreamp.t rand test (RT#118237) Fedora Patch20: Reap child in case where exception has been thrown (RT#114722) Fedora Patch21: Fix using regular expressions containing multiple code blocks (RT#117917) Fedora Patch200: Link XS modules to libperl.so with EU::CBuilder on Linux Fedora Patch201: Link XS modules to libperl.so with EU::MM on Linux Built under linux Compiled at Jan 7 2014 14:47:21 %ENV: PERL5LIB="/home/tore/public/share/perl" PERL_LOCAL_LIB_ROOT="/home/tore/public/share/perl" PERL_MB_OPT="--install_base /home/tore/public/share/perl" PERL_MM_OPT="INSTALL_BASE=/home/tore/public/share/perl" @INC: /home/tore/public/share/perl /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 . $ rpm -qa perl-Net-DNS perl-Net-DNS-0.77-1.fc21.x86_64 $ lsb_release -a LSB Version: :core-4.1-amd64:core-4.1-noarch:cxx-4.1-amd64:cxx-4.1-noarch:desktop-4.1-amd64:desktop-4.1-noarch:languages-4.1-amd64:languages-4.1-noarch:printing-4.1-amd64:printing-4.1-noarch Distributor ID: Fedora Description: Fedora release 20 (Heisenbug) Release: 20 Codename: Heisenbug $ cat /etc/resolv.conf nameserver 2001:4600:4:fff::54 nameserver :: $ time perl -MNet::DNS -e 'Net::DNS::Resolver->new();' real 5m20.408s user 0m0.082s sys 0m0.018s $ sed -i 2d /etc/resolv.conf $ time perl -MNet::DNS -e 'Net::DNS::Resolver->new();' real 0m0.081s user 0m0.076s sys 0m0.003s
  Mon Jun 30 11:35:53 2014 rwfranks [...] acm.org - Correspondence added
From: rwfranks [...] acm.org
On Sun Jun 29 06:29:22 2014, tore@fud.no wrote: Show quoted text
> For some reason I ended up with a /etc/resolv.conf containing the > following entries: > > nameserver 2001:4600:4:fff::54 > nameserver :: >
_ip_is_ipv6() failed to recognise :: as IPv6 so it tried to resolve it as a name! Show quoted text
> This breaks Net::DNS - the ->new() method hangs for 5 minutes before > returning. >
It does not actually break Net::DNS, just causes it to do something which can not succeed, because it assumes that in the absence of a valid nameserver configuration the query should be sent to a nameserver running on the local host, which I assume you do not have. The query timed out after 5 minutes of futile attempts.
  Mon Jun 30 11:35:54 2014 The RT System itself - Status changed from 'new' to 'open'
  Thu Jul 10 11:02:48 2014 rwfranks [...] acm.org - Correspondence added
From: rwfranks [...] acm.org
On Mon Jun 30 11:35:53 2014, rwfranks@acm.org wrote: Show quoted text
> On Sun Jun 29 06:29:22 2014, tore@fud.no wrote:
> > For some reason I ended up with a /etc/resolv.conf containing the > > following entries: > > > > nameserver 2001:4600:4:fff::54 > > nameserver :: > >
> > _ip_is_ipv6() failed to recognise :: as IPv6 so it tried to resolve it > as a name! >
_ip_is_ipv6() bug fixed in 0.78, so it will not hang in resolver->new().
  Tue Jul 29 06:23:54 2014 NLNETLABS [...] cpan.org - Correspondence added
Fixed in 0.78
  Tue Jul 29 06:23:57 2014 NLNETLABS [...] cpan.org - Status changed from 'open' to 'resolved'