res_nquery for ipv6 DNS server issue on libc2-27.

res_nquery for ipv6 DNS server issue on libc2-27.

[Vishnu Prasad S K (Nokia)]

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Hi Team,

We are using the below code to send DNS TXT query to specific ipv6 DNS server IP in "bootstrapDNS<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootstrapDNS>".

In libc2-21.so this piece of code is working fine TXT query would always go to bootstrapDNS<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootstrapDNS> server.



We upgraded to libc2-27, on top this the below code is not working, res_nquery() is sending query to random IP's and not to bootstrapDNS<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootstrapDNS> server IP.

Is there any change in libc2-27 on using _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsaddrs<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsaddrs&project=femto_22.1_nightly> fields??



How to make our TXT query go to bootstrapDNS<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootstrapDNS> server on libc2-27?





    _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nscount6<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nscount6&project=femto_22.1_nightly> = 0;

    _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>.nscount<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nscount&project=femto_22.1_nightly> = 0;

    _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsaddrs<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsaddrs&project=femto_22.1_nightly>[0] = NULL<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=NULL&project=femto_22.1_nightly>;

    res_init<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=res_init&project=femto_22.1_nightly>();

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>.options<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=options&project=femto_22.1_nightly>|=RES_ROTATE<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=RES_ROTATE&project=femto_22.1_nightly>;

        bootIn6<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootIn6>->sin6_family<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=sin6_family&project=femto_22.1_nightly> = AF_INET6<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=AF_INET6&project=femto_22.1_nightly>;

        bootIn6<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootIn6>->sin6_port<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=sin6_port&project=femto_22.1_nightly> = htons<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=htons&project=femto_22.1_nightly>(53);

        int ret<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=ret&project=femto_22.1_nightly> = inet_pton<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=inet_pton&project=femto_22.1_nightly>(AF_INET6<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=AF_INET6&project=femto_22.1_nightly>, bootstrapDNS<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootstrapDNS>.c_str<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=c_str&project=femto_22.1_nightly>(), bootIn6<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootIn6>->sin6_addr<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=sin6_addr&project=femto_22.1_nightly>.s6_addr<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=s6_addr&project=femto_22.1_nightly>);

        OUTLOG_LEVEL<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=OUTLOG_LEVEL&project=femto_22.1_nightly>(IKEMLOG_DETAIL<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=IKEMLOG_DETAIL&project=femto_22.1_nightly>, 7, "Boot DNS is IPv6, ret is %d",ret<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=ret&project=femto_22.1_nightly>);

      #if defined(HW_FAMILY_fsm9xxx<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=HW_FAMILY_fsm9xxx&project=femto_22.1_nightly>)

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>.nscount<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nscount&project=femto_22.1_nightly> = 3;

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nscount6<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nscount6&project=femto_22.1_nightly> = 3;

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nscount<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nscount&project=femto_22.1_nightly> = 0;

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsaddrs<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsaddrs&project=femto_22.1_nightly>[0] = bootIn6<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootIn6>;

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsaddrs<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsaddrs&project=femto_22.1_nightly>[1] = bootIn6<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootIn6>;

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsaddrs<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsaddrs&project=femto_22.1_nightly>[2] = bootIn6<http://in05vubld027.in.alcatel-lucent.com/source/xref/femto_22.1_nightly/vobs/fbsr_plat/ikem/ikem/src/ikem_DNSManagement.cc#bootIn6>;



        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsmap<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsmap&project=femto_22.1_nightly>[0] = MAXNS<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=MAXNS&project=femto_22.1_nightly> + 1;

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsmap<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsmap&project=femto_22.1_nightly>[1] = MAXNS<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=MAXNS&project=femto_22.1_nightly> + 1;

        _res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>._u<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_u&project=femto_22.1_nightly>._ext<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_ext&project=femto_22.1_nightly>.nsmap<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=nsmap&project=femto_22.1_nightly>[2] = MAXNS<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=MAXNS&project=femto_22.1_nightly> + 1;


res_nquery<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=res_nquery&project=femto_22.1_nightly>(&_res<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=_res&project=femto_22.1_nightly>,fqdn<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=fqdn&project=femto_22.1_nightly>, C_IN<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=C_IN&project=femto_22.1_nightly>, T_TXT<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=T_TXT&project=femto_22.1_nightly>, answer<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=answer&project=femto_22.1_nightly>, sizeof(answer<http://in05vubld027.in.alcatel-lucent.com/source/s?defs=answer&project=femto_22.1_nightly>));


Regards,
Vishnu.

Re: res_nquery for ipv6 DNS server issue on libc2-27.

[Florian Weimer]

Vishnu,

your message is full of internal alcatel-lucent.com URLs and is
therefore unreadable.

What you are seeing might be a side effect of /etc/resolv.conf
auto-reloading.  Are the IPv6 addresses that are incorrectly contacted
listed in /etc/resolv.conf?

Thanks,
Florian

RE: res_nquery for ipv6 DNS server issue on libc2-27.

[Vishnu Prasad S K (Nokia)]

Hi Florian,
Thanks for your attention to this.

>>>> Are the IPv6 addresses that are incorrectly contacted listed in /etc/resolv.conf?
Yes the ip's are picked randomly from /etc/resolv.conf.
How to force res_nquery to use only the IP's we fill in _res._u._ext.nsaddrs??



Pasting the query again by removing hyperlinks.

We are using the below code to send DNS TXT query to specific ipv6 DNS server IP in "bootstrapDNS".
In libc2-21.so this piece of code is working fine TXT query would always go to bootstrapDNS server.
 
We upgraded to libc2-27, on top of this the below code is not working, res_nquery() is sending query to random IP's and not to bootstrapDNS server IP.
Is there any change in libc2-27 on using
We are using the below code to send DNS TXT query to specific ipv6 DNS server IP in "bootstrapDNS".
In libc2-21.so this piece of code is working fine TXT query would always go to bootstrapDNS server.

We upgraded to libc2-27, on top of this the below code is not working, res_nquery() is sending query to random IP's and not to bootstrapDNS server IP.
Is there any change in libc2-27 on using _res._u._ext.nsaddrs fields??

How to make our TXT query go to bootstrapDNS server on libc2-27? 


    _res._u._ext.nscount6 = 0;
    _res.nscount = 0;
    _res._u._ext.nsaddrs[0] = NULL;
    res_init();
        _res.options|=RES_ROTATE;
        bootIn6->sin6_family = AF_INET6;
        bootIn6->sin6_port = htons(53);
        int ret = inet_pton(AF_INET6, bootstrapDNS.c_str(), bootIn6->sin6_addr.s6_addr);
        OUTLOG_LEVEL(IKEMLOG_DETAIL, 7, "Boot DNS is IPv6, ret is %d",ret);
      #if defined(HW_FAMILY_fsm9xxx)
        _res.nscount = 3;
        _res._u._ext.nscount6 = 3;
        _res._u._ext.nscount = 0;
        _res._u._ext.nsaddrs[0] = bootIn6;
        _res._u._ext.nsaddrs[1] = bootIn6;
        _res._u._ext.nsaddrs[2] = bootIn6;

        _res._u._ext.nsmap[0] = MAXNS + 1;
        _res._u._ext.nsmap[1] = MAXNS + 1;
        _res._u._ext.nsmap[2] = MAXNS + 1;

res_nquery(&_res,fqdn, C_IN, T_TXT, answer, sizeof(answer));


Regards,
Vishnu.

-----Original Message-----
From: Florian Weimer <fweimer@redhat.com> 
Sent: Monday, August 28, 2023 5:15 PM
To: Vishnu Prasad S K (Nokia) via Libc-alpha <libc-alpha@sourceware.org>
Cc: Vishnu Prasad S K (Nokia) <vishnu.prasad_s_k@nokia.com>
Subject: Re: res_nquery for ipv6 DNS server issue on libc2-27.

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Vishnu,

your message is full of internal alcatel-lucent.com URLs and is therefore unreadable.

What you are seeing might be a side effect of /etc/resolv.conf auto-reloading.  Are the IPv6 addresses that are incorrectly contacted listed in /etc/resolv.conf?

Thanks,
Florian

Re: res_nquery for ipv6 DNS server issue on libc2-27.

[Florian Weimer]

* Vishnu Prasad S. K.:

> Hi Florian,
> Thanks for your attention to this.
>
>>>>> Are the IPv6 addresses that are incorrectly contacted listed in /etc/resolv.conf?

> Yes the ip's are picked randomly from /etc/resolv.conf.
> How to force res_nquery to use only the IP's we fill in
> _res._u._ext.nsaddrs??

>     _res._u._ext.nscount6 = 0;
>     _res.nscount = 0;
>     _res._u._ext.nsaddrs[0] = NULL;
>     res_init();
>         _res.options|=RES_ROTATE;
>         bootIn6->sin6_family = AF_INET6;
>         bootIn6->sin6_port = htons(53);
>         int ret = inet_pton(AF_INET6, bootstrapDNS.c_str(), bootIn6->sin6_addr.s6_addr);
>         OUTLOG_LEVEL(IKEMLOG_DETAIL, 7, "Boot DNS is IPv6, ret is %d",ret);
>       #if defined(HW_FAMILY_fsm9xxx)
>         _res.nscount = 3;
>         _res._u._ext.nscount6 = 3;
>         _res._u._ext.nscount = 0;
>         _res._u._ext.nsaddrs[0] = bootIn6;
>         _res._u._ext.nsaddrs[1] = bootIn6;
>         _res._u._ext.nsaddrs[2] = bootIn6;
>
>         _res._u._ext.nsmap[0] = MAXNS + 1;
>         _res._u._ext.nsmap[1] = MAXNS + 1;
>         _res._u._ext.nsmap[2] = MAXNS + 1;
>
> res_nquery(&_res,fqdn, C_IN, T_TXT, answer, sizeof(answer));

Auto-reloading should not happen for res_nquery, so this code shouldn't
need any changes.  I suggest you try to figure out why
__resolv_conf_load is called in your situation.

Thanks,
Florian

RE: res_nquery for ipv6 DNS server issue on libc2-27.

[Vishnu Prasad S K (Nokia)]

>>>> Auto-reloading should not happen for res_nquery, so this code shouldn't need any changes.  I suggest you try to figure out why __resolv_conf_load is called in your situation.

I even tried updating the /etc/resolv.conf with only the required IP before calling res_nquery(), in this case looks like the DNS packet is not shown in the pcap captured on the device where I am calling res_query, maybe it is getting discarded in kernel/glibc or not even formed.


Regards,
Vishnu.

-----Original Message-----
From: Florian Weimer <fweimer@redhat.com> 
Sent: Monday, August 28, 2023 6:06 PM
To: Vishnu Prasad S K (Nokia) <vishnu.prasad_s_k@nokia.com>
Cc: Vishnu Prasad S K (Nokia) via Libc-alpha <libc-alpha@sourceware.org>
Subject: Re: res_nquery for ipv6 DNS server issue on libc2-27.

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* Vishnu Prasad S. K.:

> Hi Florian,
> Thanks for your attention to this.
>
>>>>> Are the IPv6 addresses that are incorrectly contacted listed in /etc/resolv.conf?

> Yes the ip's are picked randomly from /etc/resolv.conf.
> How to force res_nquery to use only the IP's we fill in 
> _res._u._ext.nsaddrs??

>     _res._u._ext.nscount6 = 0;
>     _res.nscount = 0;
>     _res._u._ext.nsaddrs[0] = NULL;
>     res_init();
>         _res.options|=RES_ROTATE;
>         bootIn6->sin6_family = AF_INET6;
>         bootIn6->sin6_port = htons(53);
>         int ret = inet_pton(AF_INET6, bootstrapDNS.c_str(), bootIn6->sin6_addr.s6_addr);
>         OUTLOG_LEVEL(IKEMLOG_DETAIL, 7, "Boot DNS is IPv6, ret is %d",ret);
>       #if defined(HW_FAMILY_fsm9xxx)
>         _res.nscount = 3;
>         _res._u._ext.nscount6 = 3;
>         _res._u._ext.nscount = 0;
>         _res._u._ext.nsaddrs[0] = bootIn6;
>         _res._u._ext.nsaddrs[1] = bootIn6;
>         _res._u._ext.nsaddrs[2] = bootIn6;
>
>         _res._u._ext.nsmap[0] = MAXNS + 1;
>         _res._u._ext.nsmap[1] = MAXNS + 1;
>         _res._u._ext.nsmap[2] = MAXNS + 1;
>
> res_nquery(&_res,fqdn, C_IN, T_TXT, answer, sizeof(answer));

Auto-reloading should not happen for res_nquery, so this code shouldn't need any changes.  I suggest you try to figure out why __resolv_conf_load is called in your situation.

Thanks,
Florian

Re: res_nquery for ipv6 DNS server issue on libc2-27.

[Florian Weimer]

* Vishnu Prasad S. K.:

>>>>> Auto-reloading should not happen for res_nquery, so this code shouldn't need any changes.  I suggest you try to figure out why __resolv_conf_load is called in your situation.
>
> I even tried updating the /etc/resolv.conf with only the required IP
> before calling res_nquery(), in this case looks like the DNS packet is
> not shown in the pcap captured on the device where I am calling
> res_query, maybe it is getting discarded in kernel/glibc or not even
> formed.

You'll have to debug this in your environment.  All this sounds highly
unusual.  There must be something we are missing.

Thanks,
Florian