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

[Antony Stone]

On Saturday 11 December 2021 at 14:12:14, Sergey Safarov wrote:

> You can check DNS response.
> I think there may be a set flag that indicates "partial response."
> In this case, the client should switch transport used to send requests from
> UDP to TCP.
> 
> As I know Freewithch (libsofia) do not support DNS request via TCP and this
> lead to failed DNS lookup.

That's not what the source code seems to indicate.

src/mod/endpoints/mod_sofia/sip-dig.c contains:

--------
The sip-dig utility accepts following command line options:

-p protoname
Use named transport protocol. The protoname can be either
well-known, e.g., "udp", or it can specify NAPTR service and SRV
identifier, e.g., "tls-udp/SIPS+D2U/_sips._udp.".

--udp
Use UDP transport protocol.

--tcp
Use TCP transport protocol.

--tls
Use TLS over TCP transport protocol.

--sctp
Use SCTP transport protocol.

--tls-sctp
Use TLS over SCTP transport protocol.

--no-sctp
Ignore SCTP or TLS-SCTP records in the list of default transports.
This option has no effect if transport protocols has been explicitly
listed.

-4
Query IP4 addresses (A records)

-6
Query IP6 addresses (AAAA records).

-v
Be verbatim.
--------

I do wonder whether that last comment should be "Be verbose", but I can't say 
for certain :)

However, this strongly suggests that sofia_dig / sip_dig  does support TCP 
lookups.  I have no idea whether that means it will automatically fail over to 
a TCP lookup if the UDP response is "too large".


Antony.

-- 
Normal people think "If it ain't broke, don't fix it".
Engineers think "If it ain't broke, it doesn't have enough features yet".

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