[Blink] Blink Ubuntu DNS lookup deadlock?
g4-lisz at tonarchiv.ch
g4-lisz at tonarchiv.ch
Thu Dec 1 04:04:26 CET 2022
Hi,
when it didn't work, I restarted Blink several times, so the lifetime
shouldn't be the reason in my case...
As soon I have this problem again I will do a more thorough analyse of
the DNS packets received.
Thanks for the hint with the proxy and port settings. This should solve
the issue for me.
Best regards
Till
On 30.11.22 20:15, Tijmen de Mes wrote:
> Hi
>
> AFIAK you should always get that it ignores the CNAME. Why it
> sometimes behaves different I can’t tell. I run a test script here
> and I got it always, unless the lifetime of the resolver was reached.
> Then I got timeouts.
>
> So it could be that you’re hitting a timeout or a lifecycle timeout of
> the resolver, but from remote I can’t really tell. For lookups
> dnspython is used.
>
> To mitigate the issue, you could specify the port and proxy and it
> should just do an A lookup and not the NAPTR, SRV, A.
>
> To do this, go to Server Settings in the SIP account and add an
> outbound proxy and port, where outbound proxy is
> guest1.voipgateway.org <http://guest1.voipgateway.org> and the port 5060
>
> Best regards,
>
> Tijmen de Mes
> —
> AG Projects
>
>> Op 30 nov. 2022, om 18:17 heeft g4-lisz at tonarchiv.ch het volgende
>> geschreven:
>>
>> It's really strange, right now it's working but I don't know what has
>> changed.
>>
>> Again I did some network sniffing on port 53 and it seems a bit
>> random how Blink is reacting to the DNS replies: Sometimes it simply
>> ignores the CNAME answer to the NAPTR and doesn't send a request for
>> ws1.voipgateway.org <http://ws1.voipgateway.org>. Sometimes it sends
>> a NAPTR request for ws1.voipgateway.org <http://ws1.voipgateway.org>...
>>
>> IMHO the same randomness decides if everything works or fails: If it
>> interprets the NAPTR replies as "contains no answer", then the SRV
>> requests are also sent and interpreted correctly.
>> If the first request is mistakenly handled like a timeout, all the
>> other requests are not sent and the whole process seems to block
>> somewhere.
>>
>> Some timing issue in the DNS resolve threads?
>>
>> Cheers
>> Till
>>
>> On 30.11.22 15:42, g4-lisz at tonarchiv.ch wrote:
>>> Hi
>>>
>>> thank you for your replies.
>>>
>>> I'm a bit more familiar with DNS than with VOIP... If I get it right
>>> the NAPTR is optional and SIP should work without it.
>>>
>>> CNAME can always be a reply to a DNS lookup, it just means: The name
>>> you are looking for is an alias, i.e. guest1.voipgateway.org
>>> <http://guest1.voipgateway.org> is a virtual domain. IMHO Blink does
>>> the right thing and sends a second request for ws1.voipgateway.org
>>> <http://ws1.voipgateway.org>.
>>>
>>> But for ws1.voipgateway.org <http://ws1.voipgateway.org> there's a
>>> NAPTR either. The SOA reply only means that this an authoritative
>>> answer.
>>>
>>> IMHO the problem comes with the second DNS reply which contains only
>>> a SOA. Blink seams not to handle this and runs into a timeout.
>>>
>>> Strangely enough the whole issue doesn't always appear and all works
>>> fine sometimes. Then I get the same log lines like Timen de Mes:
>>>
>>> 2022-11-30 15:35:49.340913 [blink 2]: DNS lookup NAPTR
>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed: DNS
>>> response contains no answer
>>> 2022-11-30 15:35:49.405083 [blink 2]: DNS lookup SRV
>>> _sip._udp.guest1.voipgateway.org <http://udp.guest1.voipgateway.org>
>>> failed: DNS record does not exist
>>> 2022-11-30 15:35:49.463001 [blink 2]: DNS lookup SRV
>>> _sip._tcp.guest1.voipgateway.org <http://tcp.guest1.voipgateway.org>
>>> failed: DNS record does not exist
>>> 2022-11-30 15:35:59.932458 [blink 2]: DNS lookup SRV
>>> _sips._tcp.guest1.voipgateway.org
>>> <http://tcp.guest1.voipgateway.org> failed: DNS record does not exist
>>> 2022-11-30 15:35:59.960770 [blink 2]: DNS lookup A
>>> guest1.voipgateway.org <http://guest1.voipgateway.org> succeeded,
>>> ttl=3600: 212.117.203.57
>>>
>>> Best regards
>>> Till
>>>
>>> On 30.11.22 12:10, Adrian Georgescu wrote:
>>>> $dig cname guest1.voipgateway.org <http://guest1.voipgateway.org>
>>>>
>>>> ;; QUESTION SECTION:
>>>> ;guest1.voipgateway.org <http://guest1.voipgateway.org>. IN CNAME
>>>>
>>>> ;; ANSWER SECTION:
>>>> guest1.voipgateway.org <http://guest1.voipgateway.org>. 21600
>>>> IN CNAME ws1.voipgateway.org <http://ws1.voipgateway.org>.
>>>>
>>>> The CNAME should not be there for the domain name.
>>>>
>>>> —
>>>> Adrian
>>>>
>>>>
>>>>
>>>>
>>>>> On 30 Nov 2022, at 07:15, Tijmen de Mes <tijmen at ag-projects.com>
>>>>> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> I looked at it a bit more and the fact that a CNAME is returned
>>>>> could happen.
>>>>>
>>>>> However in my Blink I can’t reproduce this fault, I used the
>>>>> domain guest1.voipgateway.org <http://guest1.voipgateway.org> and
>>>>> I could register(?), if I made a call I got a prompt.
>>>>>
>>>>> This is how my logs look:
>>>>>
>>>>> 1 2022-11-30 10:59:46.901093 [blink 4977]: DNS lookup NAPTR
>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed: DNS
>>>>> response contains no answer
>>>>> 2 2022-11-30 10:59:46.901540 [blink 4977]: DNS lookup SRV
>>>>> _sips._tcp.guest1.voipgateway.org
>>>>> <http://tcp.guest1.voipgateway.org> failed: DNS record does not exist
>>>>> 3 2022-11-30 10:59:46.901950 [blink 4977]: DNS lookup SRV
>>>>> _sip._tcp.guest1.voipgateway.org
>>>>> <http://tcp.guest1.voipgateway.org> failed: DNS record does not exist
>>>>> 4 2022-11-30 10:59:46.902359 [blink 4977]: DNS lookup SRV
>>>>> _sip._udp.guest1.voipgateway.org
>>>>> <http://udp.guest1.voipgateway.org> failed: DNS record does not exist
>>>>> 5 2022-11-30 10:59:46.902618 [blink 4977]: DNS lookup A
>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> succeeded,
>>>>> ttl=2675: 212.117.203.57
>>>>>
>>>>> I don’t have the flatpack so I can’t tell you if something is
>>>>> wrong in there. The lookups are handled by python3-sipsimple.
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Timen de Mes
>>>>> —
>>>>> AG Projects
>>>>>
>>>>>> Op 30 nov. 2022, om 10:35 heeft Tijmen de Mes
>>>>>> <tijmen at ag-projects.com> het volgende geschreven:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> The fact that you see the timeouts could be a bug.
>>>>>>
>>>>>> The problem is that a NAPTR does exist and is a CNAME? I’ve never
>>>>>> seen this and I am not sure this is even valid in DNS.
>>>>>>
>>>>>> AFAIK a NAPTR in this case should return something like:
>>>>>>
>>>>>> 20 100 "s" "SIP+D2U" "" _sip._udp.sip2sip.info
>>>>>> <http://udp.sip2sip.info>.
>>>>>> 10 100 "s" "SIP+D2T" "" _sip._tcp.sip2sip.info
>>>>>> <http://tcp.sip2sip.info>.
>>>>>> 25 100 "s" "SIPS+D2T" "" _sips._tcp.sip2sip.info
>>>>>> <http://tcp.sip2sip.info>.
>>>>>>
>>>>>> After this a SRV lookup would be done.
>>>>>>
>>>>>> Are you able to register your account?
>>>>>>
>>>>>>
>>>>>> Best regards,
>>>>>>
>>>>>> Tijmen de Mes
>>>>>> —
>>>>>> AG Projects
>>>>>>
>>>>>>> Op 29 nov. 2022, om 17:44 heeft g4-lisz at tonarchiv.ch het
>>>>>>> volgende geschreven:
>>>>>>>
>>>>>>> Hi there
>>>>>>>
>>>>>>> A few days ago I updated my OS to Pop! OS / Ubuntu 22.04 LTS
>>>>>>> with the Blink flatpack V5.5.0
>>>>>>>
>>>>>>> A few times it worked flawlessly, but most of the time, starting
>>>>>>> a call lags a lot and it simply fails with a beep after a few
>>>>>>> minutes without any further message.
>>>>>>>
>>>>>>> The logs shows issues with DNS:
>>>>>>>
>>>>>>> 2022-11-29 15:22:37.533993 [blink 2]: DNS lookup NAPTR
>>>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed:
>>>>>>> no DNS response received, the query has timed out
>>>>>>> 2022-11-29 15:22:37.534465 [blink 2]: DNS lookup SRV
>>>>>>> _sip._udp.guest1.voipgateway.org
>>>>>>> <http://udp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:22:37.534699 [blink 2]: DNS lookup SRV
>>>>>>> _sip._tcp.guest1.voipgateway.org
>>>>>>> <http://tcp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:22:37.534909 [blink 2]: DNS lookup SRV
>>>>>>> _sips._tcp.guest1.voipgateway.org
>>>>>>> <http://tcp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:22:37.535100 [blink 2]: DNS lookup A
>>>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed:
>>>>>>> no DNS response received, the query has timed out
>>>>>>> 2022-11-29 15:22:37.637499 [blink 2]: DNS lookup TXT
>>>>>>> xcap.guest1.voipgateway.org <http://xcap.guest1.voipgateway.org>
>>>>>>> failed: DNS record does not exist
>>>>>>> 2022-11-29 15:23:08.049049 [blink 2]: DNS lookup NAPTR
>>>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed:
>>>>>>> no DNS response received, the query has timed out
>>>>>>> 2022-11-29 15:23:08.049976 [blink 2]: DNS lookup SRV
>>>>>>> _sips._tcp.guest1.voipgateway.org
>>>>>>> <http://tcp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:23:08.050817 [blink 2]: DNS lookup SRV
>>>>>>> _sip._tcp.guest1.voipgateway.org
>>>>>>> <http://tcp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:23:08.051510 [blink 2]: DNS lookup SRV
>>>>>>> _sip._udp.guest1.voipgateway.org
>>>>>>> <http://udp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:23:08.052161 [blink 2]: DNS lookup A
>>>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed:
>>>>>>> no DNS response received, the query has timed out
>>>>>>> 2022-11-29 15:23:38.498519 [blink 2]: DNS lookup NAPTR
>>>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed:
>>>>>>> no DNS response received, the query has timed out
>>>>>>> 2022-11-29 15:23:38.498998 [blink 2]: DNS lookup SRV
>>>>>>> _sip._udp.guest1.voipgateway.org
>>>>>>> <http://udp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:23:38.499612 [blink 2]: DNS lookup SRV
>>>>>>> _sip._tcp.guest1.voipgateway.org
>>>>>>> <http://tcp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:23:38.500547 [blink 2]: DNS lookup SRV
>>>>>>> _sips._tcp.guest1.voipgateway.org
>>>>>>> <http://tcp.guest1.voipgateway.org> failed: no DNS response
>>>>>>> received, the query has timed out
>>>>>>> 2022-11-29 15:23:38.501826 [blink 2]: DNS lookup A
>>>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed:
>>>>>>> no DNS response received, the query has timed out
>>>>>>> 2022-11-29 15:24:08.946267 [blink 2]: DNS lookup NAPTR
>>>>>>> guest1.voipgateway.org <http://guest1.voipgateway.org> failed:
>>>>>>> no DNS response received, the query has timed out
>>>>>>>
>>>>>>> and so on.
>>>>>>>
>>>>>>> But in reality there are no DNS timeouts. IMHO the issue is that
>>>>>>> Blink doesn't handle the DNS answers right and then somehow
>>>>>>> deadlocks on the first NATPR request.
>>>>>>>
>>>>>>> I did some sniffing on port 53 and there are no DNS requests for
>>>>>>> SRV:
>>>>>>>
>>>>>>> 192.168.178.23 192.168.178.1 DNS 82 Standard query
>>>>>>> 0x1eab NAPTR guest1.voipgateway.org <http://guest1.voipgateway.org>
>>>>>>> 192.168.178.1 192.168.178.23 DNS 162 Standard query
>>>>>>> response 0x1eab NAPTR guest1.voipgateway.org
>>>>>>> <http://guest1.voipgateway.org> CNAME ws1.voipgateway.org
>>>>>>> <http://ws1.voipgateway.org> SOA ns1.backbone.ch
>>>>>>> <http://ns1.backbone.ch>
>>>>>>> 192.168.178.23 192.168.178.1 DNS 79 Standard query
>>>>>>> 0x3a0b NAPTR ws1.voipgateway.org <http://ws1.voipgateway.org>
>>>>>>> 192.168.178.1 192.168.178.23 DNS 141 Standard query
>>>>>>> response 0x3a0b NAPTR ws1.voipgateway.org
>>>>>>> <http://ws1.voipgateway.org> SOA ns1.backbone.ch
>>>>>>> <http://ns1.backbone.ch>
>>>>>>> [ ..nothing concerning VOIP...]
>>>>>>> 192.168.178.23 192.168.178.1 DNS 82 Standard query
>>>>>>> 0xb5c0 NAPTR guest1.voipgateway.org <http://guest1.voipgateway.org>
>>>>>>> 192.168.178.1 192.168.178.23 DNS 162 Standard query
>>>>>>> response 0xb5c0 NAPTR guest1.voipgateway.org
>>>>>>> <http://guest1.voipgateway.org> CNAME ws1.voipgateway.org
>>>>>>> <http://ws1.voipgateway.org> SOA ns1.backbone.ch
>>>>>>> <http://ns1.backbone.ch>
>>>>>>> 192.168.178.23 192.168.178.1 DNS 79 Standard query
>>>>>>> 0x5cba NAPTR ws1.voipgateway.org <http://ws1.voipgateway.org>
>>>>>>> 192.168.178.1 192.168.178.23 DNS 141 Standard query
>>>>>>> response 0x5cba NAPTR ws1.voipgateway.org
>>>>>>> <http://ws1.voipgateway.org> SOA ns1.backbone.ch
>>>>>>> <http://ns1.backbone.ch>
>>>>>>> [ ..nothing concerning VOIP...]
>>>>>>> 192.168.178.23 192.168.178.1 DNS 82 Standard query
>>>>>>> 0x63b5 NAPTR guest1.voipgateway.org <http://guest1.voipgateway.org>
>>>>>>> 192.168.178.1 192.168.178.23 DNS 162 Standard query
>>>>>>> response 0x63b5 NAPTR guest1.voipgateway.org
>>>>>>> <http://guest1.voipgateway.org> CNAME ws1.voipgateway.org
>>>>>>> <http://ws1.voipgateway.org> SOA ns1.backbone.ch
>>>>>>> <http://ns1.backbone.ch>
>>>>>>> 192.168.178.23 192.168.178.1 DNS 79 Standard query
>>>>>>> 0x6dce NAPTR ws1.voipgateway.org <http://ws1.voipgateway.org>
>>>>>>>
>>>>>>> The queries timeout occurs because Blink does not issue the
>>>>>>> requests. IMHO Blink does not handle the SOA replies and somehow
>>>>>>> deadlocks, so other requests are never sent.
>>>>>>>
>>>>>>> Instead it should simply return: NAPTR record does not exist. Go
>>>>>>> on...
>>>>>>>
>>>>>>> Cheers
>>>>>>> Till
>>>>>>>
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