[Freeswitch-users] Weird: Cloudflare 1.1.1.1 DNS server not working with sofia_dig

[Shaun Stokes]

DNS works over UDP by default, that is unless the UDP response contains the Truncated flag which tells the client to use TCP instead.

More information here: https://ns1.com/blog/when-dns-uses-udp-versus-tcp

I've tested this myself, FreeSWITCH ignores the Truncated flag and continues to use UDP anyway. It seems that FreeSWITCH is not RFC 2671 compliant, this would need to be developed.

There is a related open issue: https://github.com/signalwire/freeswitch/issues/907

________________________________
From: FreeSWITCH-users <freeswitch-users-bounces at lists.freeswitch.org> on behalf of Sergey Safarov <s.safarov at gmail.com>
Sent: 12 December 2021 20:37
To: FreeSWITCH Users Help <freeswitch-users at lists.freeswitch.org>
Subject: Re: [Freeswitch-users] Weird: Cloudflare 1.1.1.1 DNS server not working with sofia_dig

To reproduce the issue you can create a NAPTR record with lot of data and then try to make a call to a domain that resolved via NAPTR/SRV
In my case

Example

[safarov at safarov-dell ~]$ nslookup -type=NAPTR ok.nga911.com<http://ok.nga911.com>
;; Truncated, retrying in TCP mode.
Server: 127.0.0.53
Address: 127.0.0.53#53

Non-authoritative answer:
ok.nga911.com<http://ok.nga911.com> naptr = 100 10 "U" "LoST:findServiceByCivicAddress" "!.*!https://api.ok.nga911.com/api/v1/lost/find-service-by-civic-address!" .
ok.nga911.com<http://ok.nga911.com> naptr = 100 10 "U" "LoST:listServicesByLocation" "!.*!https://api.ok.nga911.com/api/v1/lost/list-services-by-location!" .
ok.nga911.com<http://ok.nga911.com> naptr = 100 10 "U" "LoST:listServices" "!.*!https://api.ok.nga911.com/api/v1/lost/list-services!" .
ok.nga911.com<http://ok.nga911.com> naptr = 100 10 "U" "LIS:HELD" "!.*!https://psap.ok.nga911.com/LIS/!" .
ok.nga911.com<http://ok.nga911.com> naptr = 50 500 "S" "SIPS+D2W" "" _sips._ws.ok.nga911.com<http://ws.ok.nga911.com>.
ok.nga911.com<http://ok.nga911.com> naptr = 30 300 "S" "SIP+D2U" "" _sip._udp.ok.nga911.com<http://udp.ok.nga911.com>.
ok.nga911.com<http://ok.nga911.com> naptr = 20 200 "S" "SIP+D2T" "" _sip._tcp.ok.nga911.com<http://tcp.ok.nga911.com>.
ok.nga911.com<http://ok.nga911.com> naptr = 100 10 "U" "LoST:findServiceByLocation" "!.*!https://api.ok.nga911.com/api/v1/lost/find-service-by-location!" .
ok.nga911.com<http://ok.nga911.com> naptr = 40 400 "S" "SIPS+D2T" "" _sip._tls.ok.nga911.com<http://tls.ok.nga911.com>.

Authoritative answers can be found from:

NAPTR response UDP will not contain the whole responce.
you can see

;; Truncated, retrying in TCP mode.

If response via UDP do not contains
ok.nga911.com<http://ok.nga911.com> naptr = 30 300 "S" "SIP+D2U" "" _sip._udp.ok.nga911.com<http://udp.ok.nga911.com>.

Then FS will fail place a call.


On Sun, Dec 12, 2021 at 10:15 PM Avi Marcus <avi at avimarcus.net<mailto:avi at avimarcus.net>> wrote:
Also FreeSWITCH Version 1.10.7-release-19-883d2cb662~64bit (-release-19-883d2cb662 64bit)
On debian 9.13

`sofia_dig -v @1.1.1.1<http://1.1.1.1> google.com<http://google.com>` works, with and without the -v flag.


-Avi Marcus



On Sun, Dec 12, 2021 at 8:22 PM Antony Stone <Antony.Stone at freeswitch.open.source.it<mailto:Antony.Stone at freeswitch.open.source.it>> wrote:
On Friday 10 December 2021 at 06:54:23, Podrigal, Aron wrote:

> Hi,
>
> I am experiencing weird behavior.
>
> I have my nameserver set to 1.1.1.1, doing sofia_dig returns no results,
> one request out of five succeeds.

I cannot reproduce that (FreeSwitch 1.10.7 running under Debian 10 / Devuan
3):

freeswitch> sofia_dig -v @1.1.1.1<http://1.1.1.1> google.com<http://google.com>
Preference         Weight     Transport     Port     Address
================================================================================
@1.1.1.1<http://1.1.1.1>   1       1.000         udp        5060     1.1.1.1
           2       1.000         tcp        5060     1.1.1.1
google.com<http://google.com> 1       0.250         udp        5060     2a00:1450:4009:81e::200e
           1       0.250         tcp        5060     2a00:1450:4009:81e::200e
           1       0.250         udp        5060     142.250.187.206
           1       0.250         tcp        5060     142.250.187.206

I get a result every single time.


Antony.

--
<flopsie> yes, but this is #lbw, we don't do normal

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_________________________________________________________________________

The FreeSWITCH project is sponsored by SignalWire https://signalwire.com
Enhance your FreeSWITCH install with disruptive priced SMS and PSTN services.
Build your next product on our scalable cloud platform.

Join our online community to chat in real time https://signalwire.community

Professional FreeSWITCH Services
sales at freeswitch.com<mailto:sales at freeswitch.com>
https://freeswitch.com

Official FreeSWITCH Sites
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https://freeswitch.org/confluence
https://cluecon.com

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